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Full text of "Framework for evaluating response of aquatic toxicity and fish habitat to water quality control in the Don River : supporting document #2 - strategy for improvement of Don River water quality"

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AUGUST 1991 



ISBN 0-7729-7904-9 






Report prepared by: 

Beak Consultants Limited 

and Paul Theil Associates Ltd. 

Report prepared for: 

Steering Committee 

Toronto Area Watershed Management Study 

AUGUST 1991 



Cette publication technique 
n'est disponible qu'en anglais. 

Copyright: Queen's Printer for Ontario, 1991 

This publication may be reproduced for non-commercial purposes 

with appropriate attribution. 

PIBS 1620 
log 91-2309-059 


The study "Strategy for Water Quality Management in the Don River" evaluates the costs 
and effectiveness of different source control strategies in the Don River Watershed. The 
change in concentration of 6 water quality parameters is used as the main instrument for 
evaluating effectiveness. 

This supporting document presents a framework for evaluating the effectiveness of 
control from a broader perspective. The potential response of the Don River Fishery and 
the potential response of toxicity to water quality management are evaluated. The 
framework uses an ecosystem-based set of goals for management of the watershed. The 
framework is the basis for developing a levels of protection approach to establishing 
targets for auditing water quality improvement. 

The following concepts are developed in this report: 

1. Realistic fisheries objectives are developed for the Don River Watershed (see 
Chapter 2). 

2. A toxicity model is developed to evaluate the response of the watershed to water 
quality control. Copper, nickel, zinc, total residual chlorine, ammonia, phenol and 
pentachlorophenol are included in the model (see Chapter 3). 

3. A habitat suitability index (HSI) model is established as the framework for 
evaluating the response of the fishery to water quality management (see Chapter U). 

4. Toxicity, spills, and barrier effects are incorporated into the HSI model to make the 
evaluation of water quality and fisheries management more complete and robust (see 
Chapter 5). 

5. The toxicity model is related to pathways concepts and to kinetic models of 
contaminant uptake (see Chapter 7). 

The evaluation of aquatic toxicity is based upon chemical concentration data, threshold 
values for acute or chronic toxicity, and the hypothesis that overall solution toxicity can 


be quantified using a linear addition of toxicity associated with the individual 
chemicals. The aquatic toxicity model and the effects of spills and barriers were 
incorporated into the HSI model using the same hypothesis of the HSI model involving 
numerical multiplication of various factors included in the model. 

Based upon the analysis of this report, the following conclusions are drawn (see 
Chapters 5, 6 and 8): 

1. Smallmouth bass are a good fish species to be used as an indicator of a guild of 
quality, warmwater fish species. 

2. The overall habitat of the upper and middle Don River is moderately suitable for a 
target warm water fish species, smallmouth bass. The habitat of the lower river is 

unsuitable for smallmouth bass. 

3. The major limiting factor to the fishery of the lower river is toxic components. 
These include sub-lethal concentration effects associated with total residual 
chlorine and ammonia from the STP, spills and combined sewer overflow discharges. 

if. A second major limiting factor is the bottom physical habitat of the middle and 
lower river including concrete lined open channels in the middle river, and the silty 
bottom in the back water areas of Lake Ontario. Otherwise, the bottom physical 
habitat is reasonably good due to the gradient of the river. 

3. Toxic components in other portions of the river system (due to metals and ammonia) 
have some impact upon the habitat of the fishery, but they are approximately of 
equal importance to other habitat factors such as variations in water levels and 

canopy in limiting the fishery. 

6. Management of the STP effluent, CSO's and spills in the lower river will have the 
largest immediate impact upon improving the habitat of the lower river. 

7. Mitigating measures involving restoration of canopy and riparian vegetation should 
have a significant effect upon improving the quality of the fishery. 


Additional analyses would improve the information presented in this report. They include 
the following: 

1. The effectiveness of storm water management needs further modelling analyses to 
confirm the changes postulated to occur in this report. It would appear to be 
particularly important for metals in the upper and middle zones of the river and for 
turbidity control throughout the river system. 

2. Water quality management of stormwater has a significant effect upon other water 
resource issues than strictly water quality, fisheries and ecosystem health. These 
issues include the effects of water quantity control upon: 

o baseflow rates, and groundwater hydrology; 

o baseflow temperatures; 

o peak flow rate, volume of flow, and magnitude of flow; and 

o streambank erosion (using frequency of bank-full flow as an indicator). 

These issues have been assessed in a screening way in this study but additional 
analysis is required. 

3. The measurement of aquatic toxicity and chemical characterization of water 
samples from various sources in the Don River watershed (riverine water; CSOs, 
stormwater discharges, North Toronto STP) is required to check the toxicity unit 
model presented in this report and to assist in interpreting whether a TU value of 1.0 
or other values represent toxic conditions. 

It. Additional verification data are required to confirm the importance of spills and 
toxicity relative to other physical and chemical habitat variables in the HSI model. 

5. A comprehensive fisheries management plan should be developed for the Don 
River. It could use the HSI model as the management tool and the IBI model as the 
measure of the success of the plan. The fisheries management plan would need to 
include changes in water quality, since water quality components are major limiting 
factors in the health of the fishery in the Don River. The work of this report 
provides a basis for developing such a plan. 

'H39.3 i» 

An ecosystem-based strategy for the Don River Systenn involving evaluating all 
biological niches and their interrelationships to human beings in an integrative 
framework would be an appropriate method for improving the findings of this 
study. An ecosystem-based framework was used to develop a levels of protection 
approach to establishing targets for improvement in water quality in this report. A 
continual updating and rephrasing of both the ecosystem-based framework and levels 
of protection approach, especially after public comment upon this study, "A Strategy 
for Improvement of Water Quality in the Don River", is recommended. 


Study Background 

In 1981, the Ontario Ministry of the Environment (MOE) began a study of water quality in 
the Don River, Humber River and Mimico Creek to provide baseline data to guide future 
studies. The following year, the Toronto Area Watershed Management Strategy Study 
(TAWMS) was initiated as a comprehensive and co-operative multi-agency undertaking 
towards the attainment of water quality improvements. 

The TAWMS study objectives are: 

o To better define water quality conditions with the study area; 

o To analyse the cause and effect relationships for problem constituents and areas; 

o To develop cost-effective measures for controlling pollutant loadings to the 
study area's receiving waters based on watershed needs and users. 

Although wholly funded by MOE, TAWMS receives extensive co-operation and support 
from the Metropolitan Toronto and Region Conservation Authority (MTRCA), 
Metropolitan Toronto and area municipalities. 

The TAWMS study is managed by a Steering Committee which includes representatives of 
the following: 

Ontario Ministry of the Environment 

Ontario Ministry of Natural Resources 

Metropolitan Toronto ic Region Conservation Authority 

Environment Canada 

Metropolitan Toronto 

Borough of East York 

City of Etobicoke 

City of North York 

City of Scarborough 

City of Toronto 

City of York 

Regional Municipality of York 

Regional Municipality of Peel 

Town of Richmond Hill 

Town of Vaughan 

Town of Markham 

A detailed study of the Humber River was carried out during the period 1982 to 1985. In 
1986, the TAWMS Steering Committee released a Management Plan for the Humber 
River. Recommendations which were outlined in this plan are presently being 
implemented. ^ 


The TAW MS Don River Water Quality Improvement Study was commissioned as an 
external contract to Paul Theil Associates Limited and Beak Consultants Limited in the 
spring of 1988. The study's mandate was to summarize water quality problems, relate 
these problems to sources and to provide a range of improvement actions leading to 
various levels of control for water quality improvements. Options investigated for water 
quality improvement range from no further degradation to the full restoration of water 
quality in the Don River. The findings were presented as alternatives or staged 
management strategies which will lead to several milestones or levels of water quality 

The improvement strategy incorporates findings from previous investigations of low flow 
and storm event conditions, snow melt, the status of biological communities and general 
water quality conditions within the Don River. 

Public consultation on a number of strategies for water quality improvement for the Don 
River, combined with inputs from a range of municipalities and agencies will provide 
valuable direction for drafting the final Don River Management Plan. Improvement 
strategies outlined in this report for the Don River and other rivers which drain into the 
waterfront will be considered in context of the Metro Toronto Remedial Action Plan 
(RAP), a provincial-federal initiative for protecting water quality in Toronto's 

Implementation considerations and costs are important components in this option 
selection/consultant process, since they identify in simple terms what it will take to 
achieve a range of improvements and benefits or designated uses of the Don River, This 
consultation process will also recognize the will of municipalities, government agencies, 
developers and the public to support selected undertakings to protect and enhance water 
quality in the Don River. 

The time span in which water quality improvements are to be derived and the ultimate 
costs will depend upon the levels of protection and the phasing of controls selected on 
the basis of public feedback and agency and municipality endorsement. It is recognized 
that effective improvement actions in the Don River watershed will also require creative 
solutions and new approaches by the municipalities and government agencies. 

In addition to the remedial measures proposed in the strategy, a number of immediate 
actions are presently underway to address water quality problems by means of regular 
municipal and conservation authority works and maintenance programs, or through 
Ministry of the Environment programs such as the Waterfront Water Quality 
Improvement Program which funds physical work on the watercourses, waterfront or 
sewers yielding immediate benefits. 

This document is Supporting Document 2 for the study. The complete set of study 
reports are as follows. 









Availability of Reports 

Copies of the Supporting Documents and the Summary Report for the Strategy for 
Improvement of Don River Water Quality are available through the: 

Public Information Centre 

Water Resources Branch 

135 St. Clair Avenue W. 

Suite 100 

Toronto, Ontario 

MW 1P5 

{It 16) 323- «2 1 






1.1 Ecosystem Based Water Management Plan 1.1 

1.1.1 Definition of Ecosystem Approach to Planning 1.1 

1.1.2 Cycles of Mass Between Water, Air and Land 1.2 

1.1.3 Aspects of Ecosystem Approach in this Document 1.3 

1.2 Fishery as an Integrator of Ecosystem Quality 1.* 

1.2.1 The Fishery as an Element of the Ecosystem lA 

1.2.2 Framework for Evaluating Response of Fishery 

to Water Quality Management lA 

1.2.3 Description of Habitat Suitability Index Models 1.5 
1.2.'f Application of HSI Model to Don River 1.6 
1.2.5 Addition of Aquatic Toxicity Concepts to HSI Model 1.6 

1.3 Relationship of Fisheries Management to Human Based 

Beneficial End Uses 1.6 

I A Physical Setting for Water Quality Evaluations 1.7 

I A. I Reaches Used in Study for Water Quality Evaluation 1.7 

1.'>.2 Priority Reaches 1.7 

IA.3 Water Quality Variables Selected 1.8 

iAA Evaluation of Effectiveness of Water Quality Control 1.8 

1.5 Emphasis of this Report 1.9 

1.6 Structure of Report 1.9 


2.1 Background 2.1 

2.2 Watershed Reaches for Fisheries Objectives 2.2 

2.3 Characteristics of the Lower River 2.3 
2A Characteristics of the Middle River 2.5 
2.5 Characteristics of the Upper River 2.6 

2.6 Characteristics of the Tributaries: Massey Creek, 

Wilkett Creek and German Mills Creek 2.7 

2.7 Fisheries Objectives for the Don River 2.8 


3.1 Introduction 3.1 

3.2 Toxicants 3.2 

3.3 Estimating Mixture Toxicity 3.9 

3.3.1 Model Formulation 3.9 

3.3.2 Limitations of the Model 3.11 

3.3.3 Data Requirements 3.12 
3 A Validation of the Toxicity Model 3.12 

3.5 Applications of the Mixture Toxicity Model 3.13 

3.6 Conclusions 3.1^^ 

3.7 Recommendations 3.1'f 


'f.l Framework for Fish Habitat Management and Assessment 

of Urban Impacts f.l 

UAA Habitat Suitability Index (HSI) Models f.l 

'*.1.2 HSI Model Application U.3 

1^.1.3 Priority Habitat Variables f.* 

liAA Potential Limitations ft.'f 

it.2 Selection of Target Fish Species for Don River f.5 

^♦.2. 1 Approaches to Assessing Target Species f.5 

'f.2.2 Criteria for Selecting Target Species U.7 

^.2.3 Possible Target Species ^,Z 

«f. 2.3.1 Brook Trout '».9 

'f.2.3.2 Smallmouth and/or Largemouth Bass '».9 

'*.2.3.3 Rainbow Trout 'J. 10 

li.lA Species Selected '^.ll 


it.3 Application of Habitat Suitability Index (HSI) Model 

for Smallmouth Bass to the Don River System 'f.ll 
t^A Significance of Water Temperature Limitations for 

Target Fish Species *.l* 



5.1 Original Smallmouth Bass Model 5.1 

5.2 Addition of Toxicity Components 5.1 

5.2.1 Components Selected 5.1 

5.2.2 Addition of Components to the HSI 5.3 

5.3 Impact of Toxicity, Spills and Barriers Upon the HSI 5A 



6.1 Variables Evaluated 6.1 

6.2 Predicted Effects for Non-Toxicity Components 6.1 

6.2.1 Flow Regime 6.1 

6.2.2 Water Temperatures 6.3 

6.2.3 Turbidity 6.4 
6.2.'f Bottom Habitat 6.5 

6.3 Predicted Effects of Control of Chronic Toxicity and Spills 6.6 

6.3.1 Control of TRC Components of Aquatic Toxicity 6.7 

6.3.2 Control of Other Components of Chronic Toxicity 6.8 
6A Summary of Modelling Calculations 6.8 




7.1 Environmental Pathways 7.1 

'H39.3 vii 


7.2 Models for Fish Uptake 7.2 

7.2.1 Bioconcentration Factor Approach 7.2 

7.2.2 Kinetic Approach 7.3 

7.2.3 Relationships Between Bioconcentration and Toxicity 7 A 
7.2A Recent Advances in Toxicity Testing 7,6 

7.2.5 Overview of State-of-the-Art 7.8 

7.2.6 Cumulative Effects of Different Chemicals Upon Toxicity 7.10 

7.2.7 Theoretical Construct for Toxicity Unit Model 7.11 

7.2.8 Practical Application of Toxicity Unit Model 7.13 

7.3 Influence of Total Metal Concentrations Upon Toxicity Model 7.15 
7 M Other Considerations 7.16 
7,5 Validation of Toxicity Model 7,19 

7.5.1 Methods 7,19 

7.5.2 Toxicity Results 7.19 

7.5.3 Toxicity Modelling 7,20 



8.1 General Considerations re Don River Habitat 8.1 

8.2 Use of the Index of Biotic Integrity (IBl) to Measure 

and Monitor HSI Effectiveness and Significance 8.3 

8.3 Recommendations S.'* 

8.3.1 Specific Recommendations 8.^* 

8.3.2 General Recommendations for Further Work in 

Fisheries - Water Quality Area 8.5 

SA Recommended Approach 8.6 


APPENDIX 1: Use of Ecosystem Approach to Development of 

Levels of Protection Criteria 


APPENDIX 2: Environmental Pathways Modelling as a Tool for 

Assessing the Response of Fisheries Resources 
and of Human Health to Water Quality Control in 
the Don River Watershed 



1.1 Ecosystem Based Water Management Plan 

There are a number of alternative approaches to setting environmental criteria against 
which future changes can be assessed or measured and accepted or rejected. The one 
most commonly used is to establish individual criteria for a number of physical or 
chemical parameters of water quality or flow regulation at levels which are arbitrarily 
felt to be "environmentally acceptable". A more contemporary approach has been to 
adopt the ecosystem concept for natural systems in which plant or animal communities 
or individual species are identified as being representative of a set of environmental 
criteria to be maintained or established. This has the advantage of integrating physical, 
chemical and biological elements of the environment toward a measurable and desirable 
endpoint, that of supporting a biological community or species. Physical or chemical 
criteria are not set arbitrarily, but rather relate to the habitat needs of the 
representative species selected. 

1.1.1 Definition of Ecosystem Approach to Planning 

An ecosystem is composed of various biological niches within the watershed and the 
interacting elements of water, air, land and living organisms, including man. An 
"Ecosystem Approach" to Planning is based upon using these various biological/physical 
niches as the fundamental building blocks for planning. 

An ecosystem approach may be defined as the following: 

(i) it uses the various biological niches of the watershed as the basic building blocks 

of the plan; 

(ii) it uses natural rates of cycling of material between water, air and land as one 

basis for defining unpolluted conditions; 

(iii) it views various living organisms including man as the basic biological building 
blocks of the plan; 


(iv) it defines pollution as an unbalanced ecosystem resulting from accelerated rates 

of cycling of matter or from the entry of toxic substances into these cycles 
which cannot be tolerated by particular plants or living organisms including man; 


the ecosystem provides the integrative framework for relating various human 
activities to the non-human parts of the ecosystem. 

1.1.2 Cycles of Mass Between Water, Air and Land 

An ecosystem approach to water quality planning recognizes the effect of cycles of 
material upon the various biological niches of the watershed and the linkage of humans to 
these cycles. It describes the elements of an ecosystem approach; the social, 
philosophical and ecological basis for the approach; and its advantages. 

It necessitates explicit recognition of the exchange of materials between these building 
blocks. The exchange of material which has conventionally been recognized in Water 
Resources Planning is the transport of water through the atmosphere, and subsequent 

The material exchange explicitly recognized in water quality management is the 
discharge of fecal material, nutrients, suspended solids, trace metals and toxic organics 
to the receiving water after partial or incomplete treatment. Implicitly recognized is 
food production, mining, paper production etc. in other watersheds and the transport of 
these "raw materials" into an urban basin to form building blocks for the wastes 
subsequently discharged. 

An ecosystem approach to planning "necessitates explicit recognition of the transport of 
materials such as atmospheric pollutants into and out of the Basin". The ecosystem 
approach provides the philosophic basis for a view of man as part of nature. It directs 
the efforts of 'different human institutions, industries and government agencies' toward 
treatment of the patient (the Ecosystem) rather than the symptoms of the disease. It 
relates the biological and technological activities of man to the carrying capacity of the 


These transfers of matter have led the International ]oint Commission and others to 
advocate the use of Ecosystem principles for establishing and effecting management 

1.1.3 Aspects of Ecosystem Approach Evaluated in this Document 

The application of an Ecosystem Approach to the Don River Water Quality Improvement 
Strategy requires that a holistic Ecosystem based strategy first be adopted. The 
ecosystem based strategy would take the perspective of perhaps a 50 year planning 
horizon. Then from this plan, a short term plan (with perhaps a 5-10 year planning 
horizon) and a long-term plan (with a 20 year planning; and/or a 50 year planning horizon) 
would be developed for Water Quality Management. 

An Ecosystem Approach to planning is difficult to do unless it includes all elements of 
the ecosystem. A complete analysis is based upon fisheries, water quality, terrestrial 
habitat, human values (such as human health, human safety, economic development and 
recreation), and erosion and flood control. It sets priorities for these ecosystem and 
human values. 

The study, documented in this supporting document, evaluates two crucial elements of 
the riverine portion of the ecosystem. 

o fisheries 

o aquatic toxicity (as a surrogate for deleterious impacts of degraded water quality 
upon biota in the riverine ecosystem) 

Ecosystem principles were used to develop a framework (see Table 1.1) to assist in 
evaluating the Don River fishery in the form of water quality and environmental quality 
goals for the Don River system. These are given in Appendix 1 In the form of a 
discussion which resulted from several meetings of a fisheries working group. 

'fl39.3 1.3 



1. Ouality of Life Within Great Lakes Ecosystem 

• linkage to Great Lakes ecosystem 
pride in Don River ecosystem 

• balance of economic and environmental value 

• quality of life and land ownership 

2. Fisheries, Riparian and Terrestrial Habitats 

• river beds as fish habitat 

enjoyment of pants, wildlife 

• wildlife and waterfowl and their habitats 

3. Water Quality, Public Health and Aesthetics 

contact, non-contact recreation 

• drinking water 

• fish consumption 

• aesthetics 

4. Public Safety 

• erosion and flood protection 
risk to life in valley lands 

1.2 Fishery As An Integrator of Ecosystem Quality 

1.2.1 The Fishery as an Element of the Ecosystem 

A food web involving various biological niches interacting in a balanced way is an 
indication of a healthy aquatic environment. The presence of abundant numbers of 
various predatory fish species are also key indicators, as it is essential that the food web 
be balanced and that the habitat be suitable in order to sustain and nurture such a 

The fishery in a river system and the associated water quality are elements of the 
riverine ecosystem which are contained in the water flowing within the river banks. The 
river system also interacts with other ecosystem components. This occurs through the 
hydrological cycle, transfers of matter through atmospheric pathways, discharge of the 
riverine water to a Lake Ontario, importation of various raw and finished products into 
the watershed by humans, and discharge of wastes from human systems to the river. 

1.2.2 Framework for Evaluating Response of Fishery to Water Quality Management 

There are various models which can be used as indicators of a quality environment, 
including biological models such as the Index of Biologic Integrity (IBI), and habitat 
models such as the Habitat Suitability Index (HSI) model. 

The Habitat Suitability Index model provides a tool for management by being able to 
relate instream conditions to causes of poor or good water quality, causes of poor or good 
flow rates and the presence or absence of suitable physical habitat. The IBI is not a 
management tool. Rather, it is response variable, a measure of a successful management 
plan. Accordingly, the HSI approach is used in this report as the tool for evaluating the 
present fishery in the Don River and the potential effectiveness of water quality control 
upon enhancing the fishery. 

In previous work on several rivers in the Toronto Watershed area, (e.g. Steedman, R.J.; 
1987; BEAK, 1988) it is clear that there is a strong correlation between the HSI model 
for several species and the IBI, Where there is excellent habitat with ample food and 
good clear water flowing over the bottom habitat, a well balanced ecosystem exists (e.g., 
the Rouge River). Where there is poor habitat and poor water quality, then the IBI 

itl39.3 1.* 

describes a poor, improvershed biological system devoid of many fish species (e.g., 
various sections of the Don River). 

1.2.3 Description of Habitat Suitability Index Models 

In the fisheries management field, a set of Habitat Suitability Index (HSI) models have 
been developed for major North American fish species which incorporate virtually all 
habitat information available in the scientific literature. The purpose of the HSI model 
is to identify important habitat variables for each species which can be used for impact 

The HSI model provides a habitat information for evaluating impacts on fish habitat 
resulting from water or landuse changes. The impetus for the development of these 
models was the Habitat Evaluation Procedures (U.S. Fish and Wildlife Service, 1980), a 
planning and evaluation technique that focuses on the habitat requirements of importeint 

fish species. 

Most fisheries databases contain an array of habitat and population information, but are 
descriptive in content. The HSI models are unique in that they are constrained to habitat 
information only, with an emphasis on quantitative relationships between key 
environmental variables and habitat suitability. In addition, the HSI series synthesizes 
habitat information explicity into habitat models useful in quantitative assessment. 

The series of HSI models reference numerous literature souces in an effort to consolidate 
scientific information on species-habitat relationships. The models provide a numerical 
index of habitat suitability on a 0.0 to I.O scale, based on the assumption that there is a 
positive relationship between the index and habitat carrying capacity. The models vary 
in generality and precision, due in part to the amount of available quantitative habitat 
information and the frequent qualitative nature of existing information. When possible 
models are included that are derived from site-specific population and habitat data. 

The models present hypotheses of species-habitat relationships, which vary from one 
geographical area to another, and must be adapted to the specific environmental 
conditions being considered. As well, the models consider habitat needs for different life 
stages or functions, such as spawning, juvenile rearing or migration. 

'n39.3 1.5 

Ï.IA Application of HSI Model to Don River 

To apply the HSI model to a watershed, either one or more fish species must be selected 
for evaluation, as the HSI model is species specific. In the report, one species is selected 
which represents a group of quality fish species. The selection of target species are 
given in Sections 2 and i*. 

1,2.5 Addition of Aquatic Toxicity Concepts to HSI Model 

For evaluating the Don River, the HSI model has one major limitation, it does not 
evaluate all toxic substances found in a river. It includes the primary toxic condition - 
the lack of adequate oxygen resources for respiration. A toxicity model for several 
substances is formulated in Chapter 3 and incorporated into the HSI model in Chapter 5. 

1.3 Relationship of Fisheries Management to Human Based Beneficial End Uses 

The fishery of the Don River is one major beneficial end use of any water quality 
improvement strategy. Coupled with swimming and drinking water objectives, the 
protection of aquatic biota are then three of the major bases which are used to set water 
quality guidelines (criteria or objectives). Aesthetics is a fourth major basis for water 
quality management. 

Based upon these considerations, an approach of different levels of protection has been 
developed for three major areas of water quality protection. They are: 

(i) Public health (contact, non-contact recreation; drinking water), 

(ii) Fisheries, 

(iii) Aesthetics. 

The suggested levels of water quality required to achieve different degrees of water 
quality are given in Tables 1.1, 1.2 and 1.3. These levels were developed in part as a 
result of the discussion paper given in the Appendix. The philosophy used is that, due to 
the extreme deterioration of water quality in the Don, an incremental approach to 
attaining PWQO's is in order. These levels of protection then provide one with an ability 
to measure achievements over time. 


l.'f Physical Setting for Water Quality Evaluations 

The Don River has a variety of watershed characteristics and branches. The two 
principle branches are the West Don and East Don which join near the confluence with 
Massey Creek to form the Lower Don (see Figure 1). 

l.'^.l Reaches Used in Study for Water Quality Evaluation 

The following reaches were used for evaluation of their water quality (see Summary 

Area of Don Reach 

West Don 

1. West Don Above Langstaff Road 

2. West Don to Confluence with Wilkett Creek 

3. Wilkett Creek 

^. West Don from Wilkett Creek to Main Don Confluence 

East Don 

5. East Don Above Langstaff Road 

6. Little Don Above German Mills Creek 

7. German Mills Creek 

8. Lower East Don, German Mills to Confluence 

Lower Don 

9, Massey Creek 

10, Lower Don from confluence to STP 

1 1, Lower Don from STP to Keating Channel 

The Keating Channel and Inner Harbour were not considered directly in this study. They 
are considered indirectly by the study objective of achieving water quality objectives at 
the upper end of Keating Channel and the role they play in influencing fish migration 
from the lake to the river. 

\.U.2 Priority Reaches 

To allow us to relate the effectiveness of water quality to other factors, these II 
reaches were futher prioritized (see Supporting Document 1), They are a representative 




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upper non-urban catchment (West Don above Langstaff Road), a representative middle 
reach catchment (West Don at confluence with East Don), a representative priority 
tributary (Massey Creek) and the Lower Don from the STP to Keating Channel. 

Similarly, for purposes of the fishery evaluation, it is impractical to cover this large 
number of reaches. Reaches representative of the Upper, Middle and Lower reaches 
accordingly were selected (see Chapter 2). 

IA.3 Water Quality Variables Selected 

Six variables were selected for evaluation of the effectiveness of water quality control 
(see Supporting Document 1) in a quantitative manner. They are: suspended solids, total 
phosphorus, fecal coliforms, ammonia, copper and zinc. Only four of these variables 
have a direct effect on the fishery: ammonia, copper, zinc, and suspended solids (through 
the variable turbidity). 

For evaluation of toxicity of a water to a fishery, other parameters need to be 
considered. They include: nickel, total residual chlorine, phenol, dissolved oxygen, 
pentachlorophenol, and hardness. 

Other parameters required for assessment of the habitat include water temperature. 

lAA Evaluation of Effectiveness of Water Quality Control 

All parameters are considered in the toxicity model and in the HSI model. Due to the 
lack of a modelling evaluation of the magnitude of the latter parameters (nickel, TRC, 
phenol, DO, PCP and hardness) originating from different sources, the effectiveness of 
water quality control can only be evaluated qualitatively for these parameters. 

Accordingly, in this report only a scoping level qualitative evaluation of the 
effectiveness of water quality control and upon the fishery of the Don River is 
presented. More indepth analyses are required to produce assessments which would form 
the basis for implementation of fish management in the Don River system. 

= 139.3 1.8 

1.5 Emphasis of This Report 

This report, thus emphasizes the following aspects of water quality related to the 
riverine biota: 

o A quantitative framework is developed for assessing the present fishery of the 
Don River, as it relates to habitat factors and aquatic toxicity factors (The 
emphasis is upon "framework"). 

o A new idea (hypothesis) for incorporting the effects of aquatic toxicty into a 
quantitative fisheries model (HSI) is presented. 

o The science for quantifying aquatic toxicity is critiqued to substantiate the 
hypothesis; however, additional work is required to calibrate the interpretation 
of the quantitative relationship used to incorporate aquatic toxicity into the HSI 


o The potential effects of further urban developments and water quality control 
upon fisheries habitat and aquatic toxicity are illustrated qualitatively. 

o The framework is used to prioritize directions for water quality control for 
alternative disinifection methods. 

1.6 Structure of Rep)ort 

The evaluation of the present fishery and the effectiveness of management are developed 
in this report as follows: 

Chapter 2: The present characteristics and management objectives for the Don 

River are developed in this report. 

Chapter 3: A model for evaluating toxicity of the waters of the Don is developed. 

Chapter U: The HSI model for a target fish species (smallmouth bass) is applied to 

the Don River. 

'fl39.3 1.9 

Chapter 5: Toxicity components are added to the HSI nnodel. 

Chapter 6: Impacts of further development and remediation are presented for the 

target fish species. 

Chapter 7: The impacts of water quality control upon chemical burdens in fish are 


Chapter 8: An approach for integrating water quality objectives with a fish 
management plan is presented. 

'^'^^-^ 1.10 


This section: 

o identifies features limiting the distribution and abundance of fish in the Don 

o divides the watershed into relatively homogeneous reaches; and 

o develops fisheries objectives for the watershed in general, and reaches in 

These fisheries objectives can then be used within the framework of the Don River Water 
Quality Management Plan in the development of water quality and hydrologie objectives 
for the Don. 

2.1 Background 

The Don River is highly urbanized, and fisheries resources have been adversely affected 
by barriers, turbid waters, and siltation for well over a century. The lower watershed has 
been urbanized for the longest period. The upper watershed in the Town of Richmond 
Hill and the Town of Vaughan is strongly influenced by rapidly increasing urbanization 
(this area contains one of the fastest growing populations in the country) and by 

Based on D. Martin-Down's recent research and report on the Don River fishery (Martin- 
Downs, 1988), few of the species historically present in the river remain today. The 
dominant species are white sucker, blacknose dace, longnose dace and creek chub (dubbed 
by Martin-Downs as the "big four"). Carp enter the lower river from Lake Ontario 
seasonally for spawning, and other lake species such as emerald shiners also stray into 
the Keating Channel area. The upper river (generally north of Highway 7) is still 
dominated by the "big four", but a few other species are also present (McKee and Parker, 
1986) including redside dace, a minnow recognized as sensitive to the effects of 
urbanization. A population of largemouth bass survives in the Richmond Hill Mill pond, 
and rock bass occur in the G. Lord Ross Reservoir on the West Don. Mottled sculpin, a 

ifl39.3 2.1 

species preferring cooler, high quality water and natural habitat conditions is found only 
in isolated headwater areas where these conditions are still found. Other species native 
to clean, cool southern Ontario streams, such as the brook trout and atlantic salmon, no 
longer occur in the Don River, except for MNR lands at Maple and isolated head water 
tributaries (particularly sections of the Little Don, East Don). 

The Don River, particularly the lower river (south of Steeles Avenue), supports primarily 
small adult individuals of the "big four" species (i.e., small individuals of species which 
would normally grow to large adult size). It appears that this is doe to the lack of 
physical habitat (e.g., pools, in-stream cover) for larger individuals. For example, 
suckers and creek chub could grow larger, but do not. The lack of adequate fish habitat, 
in turn, is also influenced by the high flow conditions following storm events, resulting in 
scouring of the stream bed. 

The size of the fish is also influenced by the size of the stream. For example, blacknose 
dace never seem to grow larger than the type of habitat present. That is, small streams 
do not have the physical scale of habitat required for fish to grow to a larger size. 
Whether lack of habitat (pools, instream cover) or physical scale of the tributaries are 
the limiting factors to size of fish present requires further assessment. 

Fish communities in some of the smaller streams, most notably Massey Creek, Wilkett 
Creek, and German Mills Creek, appear to be affected by periodic toxic spills. These 
have included blockages of sewers and injection of chlorine to alleviate resultant 
problems. The watersheds of Massey and German Mills Creeks are highly industrialized, 
and suspicious slugs of discoloured water have been observed during fish collection 
programs. Some of these areas appear to be devoid of fish life, despite apparently 
suitable habitat conditions for members of the "big four". 

2.2 Watershed Reaches for Fisheries Objectives 

The Don River watershed may be divided into several sections, based on watershed and 
fisheries characteristics, habitat types and stream gradient: 

o Lower River - Bloor Street to Keating Channel; Keating Channel 
o Middle River - Langstaff Road to Bloor Street 

'f 139.3 2.2 

o Upper River - North of Langstaff Road 

o Tributaries - Massey Creek, Wiikett Creek, German Mills Creek 

The characteristics of these river sections are now described below in Sections 2.3 
(Lower River), 2A (Middle River), 2.5 (Upper River) and 2.6 (the Tributaries). A 
summary of background data, etc., for each river section is given in Table 2.2.1 to 2.2.^*. 

In general, the fishery is limited by existing land use and its influence upon river 
morphology and water quality, stream gradient, and lack of riparian vegetation. The 
upper tributaries are agricultural lands being rapidly urbanized. Adjacent vegetation is 
generally non-existant. Middle sections of the river are fully urbanized while lower 
sections are bordered by discharges from old industrial areas, CSO and storm sewer 
discharges, and major transportation corridors. Some sections of the middle river have 
substantial canopy but not overhanging the river; the lower river is almost devoid of 
riparian vegetation. 

2.3 Characteristics of the Lower River 

The Keating Channel affords little true riverine habitat, and in some respects is like an 
extention of the inner harbour. The physical configuration of the channel may make the 
Don River unrecognizable as a river to various species. The channel is relatively uniform 
and there is no riparian riverbank cover. Sediments in the channel are heavily 
contaminated with oily residues. With its present configuration, the channel should not 
be expected to support a population of riverine fishes. 

An appropriate fisheries objective for Keating Channel would be to provide a more 
stabilized flow regime and a reduction in contamination from combined sewer overflows 
(CSOs) and other sewers so that fish can move more readily between the lake and the 
river. For purposes of this study, the Keating Channel was determined to be outside the 
study scope and hence, is not included herein. 

Upstream of the Keating Channel, the Don River passes through a parkland belt in the 
city core. White suckers migrate from the lake through this section in spring and 
successfully spawn in the riffle habitat found near Bloor Street. Carp also migrate 
through this section for spawning (Martin-Downs, 1988) although no evidence for 
successful reproduction has been found. 

if 139. 3 2.3 

The minimum fisheries objective for this section is the maintenance of the status quo. 
Much more is required to improve the existing fishery. Achievement of this objective 
would require that no further increases in stream flow variation occur, and that existing 
riparian vegetation in the park belt be maintained. It would probably also require that 
loadings of contaminants that are causing apparent toxic effects in upstream tributaries, 
particularly Wilkett Creek and Massey Creek, not be permitted to increase and, 
preferably, be reduced or eliminated. 

Habitat suitability index (HSI) models have been developed for various fish species by the 
U.S. Fish and Wildlife Services (USFWS, 1980). Habitat requirements for maintenance of 
the status quo or improvements in the Don River fish community can be rigorously 
identified using an HSI for a target species, so that the sensitivity of the lower Don fish 
community to changing habitat quality (streamflow, water quality) can be evaluated. 
The HSI identifies physical-chemical habitat features that can be predictively modelled, 
so that HSI sensitivity to changing streamflow-water quality can be determined. A 
predicted drop in HSI for any watershed development/control scenario would be 
incompatible with the minimum fisheries objective. 

An achievable fisheries objective for this section would be the establishment of a 
piscivore fish population which is an indicator of a restored balanced ecosystem. A 
piscovore fish is one which consumes smaller fish as its main food source. Largemouth or 
smallmouth bass appear to be relatively tolerant of organic pollution, and may be a 
reasonable indication of a restored ecosystem because: 

(i) they used to be there historically; 

(ii) they are either not present, or have a very limited distribution presently; 

(iii) the habitat conditions are appropriate for the whole life cycle of fish (spawning, 
rearing, feeding); 

(iv) by feeding upon other fish, a balanced ecosystem/food web is required to sustain 

their existance. 

The limiting factors for these species in the lower Don are probably the extreme 
variation in flows and the lack of instream cover (pools, undercut banks, brush piles, 
large rocks, aquatic vegetation, etc.). These species could probably be re-established 
through the implementation of measures to reduce peak flows and increase minimum 
flows, as well as to create appropriate instream habitat features in the river. The HSI 
can be used to define the required flow regimes for possible target species such as 
largemouth or smallmouth bass. An initial characterization of limiting factors is given in 
Section it by application of an HSI model. 

Other limiting factors in this river section are influenced by aquatic toxicity, 
particularly ammonia and total residual chlorine (TRC) discharges from the North 
Toronto Treatment Plant. Fish have an avoidance reaction to TRC in the discharge 
plume before volatilization and other reactions destroy the TRC. Since the HSI model 
does not include toxicity, substantial efforts, documented below, were spent to include 
toxicity into the HSI model. 

It may also be appropriate to consider the suitability of the lower Don River for seasonal 
use by migrating salmonid species from Lake Ontario, such as the Rainbow Trout and 
Chinook Salmon, as a water quality and river habitat criteria. This would provide further 
enhancement to the recreational fishery and the aesthetic value of the river. These 
species currently migrate into all tributaries of Lake Ontario where habitat conditions 

2.* Characteristics of the Middle River 

The characteristics of the Don River fish community in the Middle River here are similar 
to those in the lower river (south of Bloor Street). Throughout most of this section, the 
Don River consists of two major branches - the West Don and the East Don. It was felt 
that the same fisheries objectives identified for the lower river should apply to this 

The optimum fish habitat requirements for this section require further evaluation. An 
initial characterization of limiting factors is given in Section it through application of an 
HSI model. 

4139.3 2.5 

It was noted that the G. Lord Ross Reservoir on the West Don near Dufferin Avenue and 
Finch Avenue should be evaluated in terms of its present operation and morphometry. 
These two factors sigificantly influence the reservoirs habitat, but these data were not 
obtained at the completion of this study. Any means of optimizing its operation for 
controlling downstream flow and water quality should be identified, thereby helping to 
achieve downstream habitat conditions to meet fisheries objectives. 

2.5 Chsu-acteristics of the Upper River 

The upper Don River watershed is becoming rapidly urbanized. Many of the smaller 
streams (first and second order) are being channelized, and gently sloping floodplain 
areas filled in for residential, commercial and industrial development. Many of the non- 
developed stream valley areas are agricultural, with relatively little riparian 
vegetation. These streams are important in the maintenance of natural fish species and 
communities which continually augment or sustain fish populations in lower reaches of 
the river. As well, these smaller tributaries serve to regulate river flows and water 
quality conditions further downstream. Because of intense development pressure, as well 
as the higher diversity of fish in the community of the upper watershed, maintenance of 
the status quo will be more difficult. In many of the smaller tributaries, recent urban 
development (e.g., in the past 5 years) will likely require an "enhancement objective", 
rather than a "maintenance of the status quo" objective. 

Development plans often approved several years ago also involve activities such as 
channelizing or piping of small streams. In many cases, developers are proposing to fill 
in portions of floodplain areas adjacent to small order 1 and 2 streams during 
construction. This strong development pressure, extremely high land values in the area, 
and the in-grained development practices and approvals procedures that permit the 
destruction of stream valleys are causing increasing losses of fish species from individual 
stretches and tributaries. 

Implementation of the mitigative strategies in this area will be the most challenging of 
all areas of the Don River. A more proactive stance on the part of MTRCA, MNR, AND 
MOE would appear to be in order. 

if 139.3 2.6 

Tl^c MNR has a proactive stance through, 

o buffer strips, 

o no net loss policy, and 

o a commentary upon development 

In addition, priority to enhancing riverine fisheries may be given to river system such as 
the Credit, Rouge and Duffins in comparison to the Don due to the relative quality of the 
existing fishery in these watersheds. A substantial problem for these agencies appears to 
be development of guidelines which are wholestic from an ecosystem point of view, and 
subsequent inspection and enforcement of these guidelines. An additional need is the 
development of master drainage planning areas which use a subwatershed basis (i.e., a 
hydrological basis) as the planning basis, rather than political boundaries (which cross 
subwatershed boundaries) as the planning basis. 

Maintenance of the status quo should be based on the habitat requirements of the most 
sensitive species recognized in this area - the redside dace. A rare status has been 
assigned for this species to the Committee on the Status of Endangered Wildlife in 
Canada (MNR, internal memo, April, 1988). In all of Canada, the redside dace is known 
only from the Golden Horseshoe area. This species requires extensive riparian vegetation 
and relatively low turbidity. It is probable that the status quo can only be maintained in 
the upper river through elimination of channelization practices, the maintenance of 
buffer strips along streambeds, control of massive sediment loadings from construction 
areas, and the maintenance of current hydraulic regimes. The redside dace should be 
considered in the fish management evaluations, at least as a criteria. Final decisions 
upon its use whether as an indicator species or criteria need to be made in the future. 

2.6 Characteristics of the Tributaries: Massey Creek, Wilkett Creek and German 

MiUs Creek 

These small streams all appear to have habitat appropriate for fish. But they have all 
been found to have stretches that are devoid of fish life, and are apparently affected by 
toxic discharges of unknown substances. The status quo option is considered 
unacceptable for these streams. Because habitat appears suitable but no fish are found 
in some reaches, re-establishment of conditions suitable for some of the more tolerant 
endemic fish species such as one or all of the "Big Four" is desirable for these tributaries. 

^^139.3 2.7 

The HSI approach, as it is not based on chemical toxicants, is inadequate in defining 
habitat requirements for these streams. The incorporation of aquatic toxicity into the 
HSI in this study provides a basis for evaluating habitat requirements! Meeting all 
PWQO's for individual chemicals (metals, etc.) most of the time, and elimination of toxic 
events, will probably permit the achievement of this objective since other habitat 
requirements appear adequate. This may be through source control, if possible, 
elimination of CSOs, or capture and treatment of stormwaters released between peak 
flow periods (when dilution may be adequate). 

2.7 Fisheries Objectives for the Don River 

Based upon these characteristics and targets, fishery objectives were established for 
each section of the Don River and are given in Tables 2.2.1 to 2.2. ^t. The section 

headings of each table are: 

1. Section Boundaries 

2. Fisheries Objective for Section 

3. Limiting Factors to Existing Fishery 
li. Collected Species 

5. Target Species 

6. Current Water Quality Impacts Upon Fisheries 

7. Management Requirements/Focus 

8. Broad Management Criteria 

9. Management Philosophy for River Section Within Overall Watershed Perspective 

10. Tools Available for Quantifying Impacts 

1 1. General Priorities for River Section 

<* 139.3 2.8 


1.1 Section Boundaries 

head water reaches above Langstaff 

1.2 Fisheries Objective 

status quo - fish species/habitat 

no further degradation in community structure or habitat 

1.3 Limiting Factors 

riparian vegetation removal 

base flow - change small marginal stream to intermittant 

barriers to movement of fish - physical and chemical 

I A Collected Species (Martin-Downs, 1988) 

White sucker Common shiner Large mouth bass 

Redbelly dace Bluntnose minnow Blacknose dace 

Pumpkin seed Fathead minnow Longnose dace 

Yellow perch Rainbow darter Creek chub 

Mottled sculpin 3ohny darter Brook stickleback 

Brooke trout Redside dace 

1.5 Target Species 

redside dace - infrequently found due to cooler habitat/water temperature 

requirements - indicator of quality habitat 

sculpin - cooler water requirements and instream cover 

creek chub-plausible target species because HSI exists. 

1.6 Current Water Quality Im(>acts 

no direct impacts discernable; indirect - loss of streams, order 1 to 3 
turbidity from construction activities will be a major future impact 
urban development impacts - temperature, decrease in low flow 

1.7 Management Requirements/Focus 

1) maintain buffer strips at streams for riparian vegetation/canopy 

2) use of ponds to manage flows 

- reduce flood flows to lower river 

- maintain base flows to lower river 
provide fisheries/recreational use potential 
water quality improvement 

sediment trap, toxic spill retention 

3) limit barriers to fish movement 


1.7 Management Requirements/Focus - Continued... 

4) BMP's (Best Management Practice) for industrial areas - no direct industrial 
inputs to stormwater flows, i.e., floor drains in factories, gas stations, etc. 

5) restrict stream channelization/burial 

6) channel redesign to address fish habitat criteria as well as optimize land use 

- retain those channels which are natural and stable 

- redesign those which are degraded and unstable - agricultural, gravel 
extraction areas, etc. 

7) retain existing water quality - control sedimentation during construction, 
eliminate chemical spills. 

1.8 Broad Management Criteria - For Headwater Streams 

1) maintain or improve fisheries potential of headwater streams to improve food 
sources delivered to middle or lower reaches 

2) create "artificial" fisheries potential in headwater areas - such as in new 

3) protect and enhance existing fisheries potential (the existing potential is 
being rapidly lost due to urbanization). 

1.9 Management Philosophy of Upper Don Within a Watershed Perspective 

1) Fish species selected are an indication of good water quality and a balanced 

2) Fish species such as minnows are a food source for downstream fishery. 

3) The scope for management is limited because the riverine fishery of order 1 
and order 2 streams never have more than a small number of several species. 

^) Use a top down watershed approach for managing headwater areas to assist in 
improving the lower river. 

1.10 Tools Available for Quantifying Impacts 

IBI data of Steedman (1987) 

HSl for Creek Chub (USFWS, 1980) 

1.11 General Priorities for Headwater Stream 

1) maintain flow 

2) maintain habitat 

3) maintain water quality 


2.1 Section Boundaries 

Individual creeks; generally in the middle/upper reaches of the Don. 

2.2 Fisheries Objective 

1) improvement in stream habitat (creek chub indicator) 

2) mitigate water quality impacts to main river 

2.3 Limiting Factors 

chemical spills major problem 

habitat loss - channelization extensive 

barriers to fish migration (e.g., culverts; Geman Mills piped through 

Richmond Hill) 

high peak flows (note: base flows appear adequate for sustaining a fishery) 

2A Collected Species (Martin-Downs, 1988) 

White sucker Goldfish (exotic, but naturalized) 

Blacknose dace Pumpkinseed 

Longnose dace 
Cheek chub 

2.5 Target Species 

target species creek chub 

2.6 Current Water Quality Impacts 

water quality and flow conditions major issues. This limits fish fauna even 

where suitable habitat remains. Some good habitat sections remain in park 

areas (e.g., Edwards Gardens in Wilkett Cr.) 

the major effect may be spills of toxic substances such as ammonia and other 

chemicals which result in a lack of fish. 

the possibility of ammonia avoidance needs further analysis since the 

unionized ammonia levels in monitoring data are below PWQO's. 

2.7 Management Requirements/Focus 

1) spill control by ponds and other devices (see Supporting Document 3) 

2) water quality improvement - industrial sources. 

3) responses to above limiting factors. 

if) maintain/improve riparian vegetation. 


2.8 Broad Management Criteria for Tributary Streams 

maintain or improve fisheries potential in tributary streams. 

re-establish missing species; (note: habitat appears to be there, but fish are 


2.9 Management Philosophy of Tributaries Within a Watershed Perspective 

1) Many fish species which should be present, are not. The habitat appears 
adequate, suggesting that barriers or water quality may be the major limiting 

2) Proposed target fish species are an indicator or good water quality and a 
balanced ecosystem. 

3) While the area requiring management is limited because of the small sizes of 
these creeks, the scope for management is large in terms of re-establishing a 
fishery resources, especially in stretches which are devoid of fish. 

2.10 Tools Available for Quantifying Impacts 

IBI data of Steedman (1987) 

HSI for Creek Chub (USFWS, 1980) 

Toxic chemical concentrations by mass balance 

2.11 Genercil Priorities for Tributaries 

The general approach is to remove all known limiting factors and stock or allow 
recolonization as appropriate. An experimental approach to reintroduction of 
species is required, since there is considerable uncertainty about limiting factors 
and the success rate of recolonization is not well documented in the literature. 
The general priorities are: 

1) Eliminate chemical spills and other toxic substances. 

2) Modify barrier to allow fish passage or stock stream sections. (Certain 
barriers are desirable, as they prevent upstream migration of lamprey eels.) 

3) Reduce flashiness of peak flows, 
'f) Retrofit channelized areas. 


3.1 Section Boundaries 

Langstaf f Road to Bloor Street (west and east Don branches) 

3.2 Fisheries Objective 

1) Status quo as the minimum - creek chub 

2) largemouth and small mouth bass capability - ecosystem criteria 

3.3 Limiting Factors 

excessive peak flows - effects on river channel and habitats - eroded 


areas of good riparian vegetation and canopy exist in the extensive park 


poor instream habitat - shallow flows, wide channel, no instream cover, poor 

stream morphology (riffles/ pools). 

water quality problems - excessive silt loads, some toxic inputs (spills). 

some channelization. 

weir at Pottery Road is a migration obstacle for lake migrant populations, 

but also prevents lamprey movement. 

3.« Collected Species (Martin-Downs, 1988) 

White sucker Blacknose dace Johnny darter 

Goldfish Longnose dace 

Redbelly dace Creek chub 

Fathead minnow Pumpkinseed 

3.5 Target Species 

creek chub - status quo. 
smallmouth/largemouth bass 

potential capability 

represent ecosystem restoration 

predator for "big four" resident species. 

indicator of acceptable water quality/balanced fish community/food 


3.6 Current Water Quality Impacts on Fishery 

turbidity and silt loads. 

chemical spills. 

high temperature; this is probably not a major impact on a warmwater 



3.7 Management Requirements/Focus 

1) spill control 

2) water quality improvement 

3) habitat remediation for above limiting factors 
U) maintain/improve riparian vegetation 

5) investigate benefits of flow control upon erosion, since flow velocities are 
strongly influenced by the stream gradient 

3.8 Broad Management Criteria for Middle Sections 

1) maintain status quo 

2) make habitat and water quality improvements to: 

improve fishery 

act as an integrator of a more balanced ecosystem. 

3.9 Management Philosophy of Middle Reaches Within a Watershed Perspective 

1) It would be difficult to substantially alter the design of the urban areas and 
their impacts upon flow and turbidity (bank erosion). Some benefits from 
flow control may be obtained for erosion protection and the associated 
impact of turbidity upon fish. Long-term siltation is a lesser issue than 
normal due to the stream gradient. 

2) There are opportunities for achieving significant improvement by: 

improving riparian habitat. 

controlling water quality excesses associated with spills and other types of 


3.10 Tools Available for Quantifying Imp>acts 

IBI data of Steedman (1987) 

Fluvial - fish linkages established by Morris (Master's Thesis, Trent 


H51 for creek chub, smallmouth and largemouth bass. 

3.11 General Priorities for Middle Reaches 

1) Control peak flows and erosion potential. 

2) Improve fishery access for migratory purposes. 

3) Improve habitat. 
tt) Control spills. 


'^.l Section Boundaries 

Bloor Street to Keating Channel 

1f.2 Fisheries Objective 

1) As in middle reaches. 

2) Suitability for seasonal use by anadromous salmonids from Lake Ontario 
(brown trout, chinook salmon) 

*.3 Limiting Factors 

water quality - stormwater (CSO) discharges to lower river, STP input, 

industrial spills. 

channeled lower section and estuary (harbour). 

major siltation of river habitats. 

riparian vegetation minor factor. 

channel morphology major limitation - substrates, lack of riffles/pools, 

shallow depths (wide scoured channel). 

no migration obstacles (physical) currently exist. 

It A Collected Species (Martin-Downes, 1988) 

White sucker Creek chub 

Emerald shiner (lake species) Brook stickleback 

Spottail shiner (lake species) Pumpkinseed 

Fathead Carp (migratory) 
Blacknose dace 
Longnose dace 

*.5 Tcirget Species 

creek chub - status quo indicator. 

largemouth bass - ecosystem restoration (as for middle reaches). 

brown trout - representative for anadromous salmonids. 

more tolerant species for temperature and turbidity. 

for anadromous run only - not self-sustaining. 

indicator for chinook salmon, coho, etc. 

*.6 Current Water Quality Impact on Fishery 

turbidity some impact. 

temperature limits fishery to warm water species. 

perceived impact of CSO's, STP's, industrial discharge and spills; exact 

impact is not quantified. 


4.7 Management Objective/Focus 

1) achieve water quality conditions suitable for fish movement through river 
below Bloor. 

2) Short-term habitat: improvement of channel aspects related to flood 
control (channelization) below Bloor. 

3) Long-term habitat: as redevelopment occurs over the next 50 years, 
improvement should be sought. 

k) Maintain/improve riparian vegetation. 

<t.8 Broad Management Criteria for Lower Reaches 

1) Maintain status quo. 

2) Make modest improvements in: 

habitat where practical, 
water quality. 

k.3 Management Philosophy of Lower River Within a Watershed Perspective 

1) There is not much scope for management in the short term, particularly in 
the backwater areas of the Lower Don because: 

much of the lower river is extensively channelized and protected by 

dikes/retaining walls. 

fishing access is essentially non-existant along Keating Channel. 

the physical habitat does not provide much opportunity for 


- the major function of the lower river is as a passage way for: 

upstream migration. 

temporary living space for species such as carp. 
cost of extensive rehabilitation would be quite expensive and require 
many alterations to present uses of shore-line property. 

2) There is scope for management in non backwater areas, and in the long-term 

- there is a substantial valley land area which could be revegetated. 
there are substantial areas in bike paths and other publically accessible 
areas. These activities may cause increased public pressure to improve 
these regions of the valley land and of the River. 

3) There is, and probably will never be into the foreseeable future, an extensive 
recreational fishery. 

k) The immediate approach should be to maintain the status quo and establish 
an improvement in the fishery which is an indicator of improvement in 

5) For the long term (50 to 100 year planning horizon), a change in the 

urban/industrial design as old buildings are replaced by new buildings will 
allow for habitat improvements which assist the development of the channel 
into habitat appropriate for the whole life cycle of the fishery of the Lower 


(f.lO General Priorities For Lower Reaches 

1) Improve water quality. 

2) Establish target species which can be used as an indicator in the 
improvement of habitat conditions and aesthetics and monitor their 

3) Improve fish habitat as urban design changes (over long term planning 


3.1 Introduction 

Toxicity is measured by exposing sensitive life stages of aquatic organisms to a chemical 
solution or mixture and determining the concentration that produces a response in half 
the population (lethality - LC50; sublethal effect - EC50) or identifying the highest 
concentration that produces no effect (highest no observed effect concentration - 
NOEC). It is used routinely among all industrial sectors to measure effluent toxicity and 
to estimate discharge mixing zones and identify areas where mixing would conflict with 
more sensitive biological or human uses in receiving waters. National tests have been 
documented and are continually being updated by Environment Canada which will cite 
specific organisms and sensitive life stages of aquatic organism that can be used to 
evaluate acute, lethal and sublethal toxicity. 

Biological tests are fully integrative of the toxicity of all compounds present in a sample 
and the influences that the physical and chemical conditions of the sample (pH, 
temperature, hardness) have on the potency of the chemicals and their mixtures. The 
exposed organism expresses the total toxicity and therefore represents a comprehensive 
manifestation of the effects of a sample. However, it is not always possible to conduct 
toxicity tests nor is it always necessary, in order to determine whether ambient waters 
might be toxic to or limit the use of, sensitive life stages of aquatic life. Chemical 
analysis is often conducted on site and often provides information on water quality. This 
chemical information can also provide a rough indication of toxicity based on known 
toxic levels of compounds and the influence of chemical and physical conditions on their 

This chapter summarizes the toxicity of frequently monitored chemicals in ambient 
waters and describes how their potency is affected. The toxicity of the compounds and 
their interactions have been described mathematically so that useful estimates of 
toxicity (to fish) can be generated from chemical measurements. These models require 
testing on actual samples to calibrate their interpretation in a highly accurate manner. 
It is probable that toxicity testing of complex effluents will be required for the 
forseeable future to give full accuracy. These models, while incomplete, clearly identify 
critical data required for ambient water quality assessment and they may be useful for 

^^139.3 3.1 

watershed management when applied via indicators such as the HSI, (Habitat Suitability 
Index) model. 

3.2 Toxicants 

The toxicity of the following compounds has been described in great detail in the open 
literature even if the mechanisms are not well understood. This section is not intended 
as a review but a concise outline of the latest descriptions of the behaviour of their 
toxicity. The intent is to focus on the estimate of toxicity for each compound and 
identify the factors influencing their potency and finally to highlight data requirements 
essential to estimating their toxicity. Two measures of toxicity have been presented in 
this overview which are related to duration of exposure, acute (short term) and chronic 
(long term). 

Acute toxicity is generally regarded as lethality that will occur in trout after an 
exposure period of 96 hours (four days). In reality most mortality occurs within the first 
Ik-i^S) hours. As an alternative to using the LC50 estimate for lethal response, the "no 
observed effect concentration" (NOEC) level was used, where possible, to provide a 
greater level of confidence in predicting non-lethal conditions. The use of the NOEC is 
more appropriate, in that, when used in a prediction model, the estimated cumulative 
effect concentration to produce no mortality is calculated. If only LC50's are used, the 
cumulative toxic units estimate whether 50% mortality might occur. Since there is 
greater concern in avoiding fish mortality altogether rather than sustaining 50% 
mortality, the use of NOEC values is of greater interest. 

The use of NOEC has several potential drawbacks. From a modelling or predictive point 
of view it would be most useful to use the most robust population estimator. This is 
clearly the LC50, and not a NOEC. Utility of a NOEC depends strongly on experimental 
design (i.e. interval of test concentrations). If "avoiding fish mortality" is the aim, then 
a safety factor should be applied to the cumulative toxic units based TUs derived from 

The use of two different estimates of acute lethality (LC50 and NOEC values) does not 
violate the requirement of combining similar data into a model. The final estimated 
value becomes lower and therefore more conservative as additional NOEC values are 

fl39.3 3.2 

The purpose of using lethality data in this way is to estimate whether the chemical 
quality of a water sample containing a mixture of low level toxicants, is likely to be 
lethal to fish life. 

Chronic toxicity estimates are drawn from water quality reviews that describe the 
chemical concentrations above which sublethal effects are likely to occur in sensitive 
life stages of aquatic life. The sublethal responses include early life stage survival, 
hatching, growth, and reproduction. The organisms include fish and invertebrates. 
Chronic effects might be anticipated if ambient water concentrations continuously 
exceed the chronic effect level for a critical period coinciding with sensitive life stage 
development of target organisms. This period will vary according to the time of the year 
but might consider any 20-30 day duration. This is particularly appropriate for cool 
water species. 


Copper Is one of the most extensively studied metals and is the best described 
toxicologically. The toxicity of copper is most influenced by water hardness. 

A thorough evaluation of the available aquatic toxicity database has been completed by 
the U.S. EPA (1986). One hour and four day average values have been derived to protect 
freshwater aquatic life and effect levels are influenced by water hardness. Dissolved 
copper Is the predictor of toxicity. Note that this differs from data available in the 
PWQMN data base which measures total metal rather than dissolved forms. Hence 
dissolved forms cannot be measured accurately. Procedures for estimating dissolved 
forms are given in Chapter 7.3. The U.S. EPA recommends measurement of "acid 
soluble" copper but the method has not been developed. 

The following relationships (USEPA, 1986) estimate the NOEC values of dissolved {0.1*5 
um filtered) copper to protect aquatic life. 

1 hour average = e^°-^'*22 (In (hardness)) - l.'f6^) ^^^/l 

'f day average = g^O-*^''^ ^^ (hardness)) - 1.^65) ^g/L 
Either value can be used in the model according to type of sample collected. 
'fl39.3 3,3 

The Canadian Water Quality Guidelines (CCREM) to protect aquatic life against chronic 
exposure to copper ranges from 0.002 - 0.00'* rng/L as a function of hardness (errata 
sheet, Dec. 1989). These values are adopted as the chronic value in the model. 


The U.S. EPA (1986) has extensively reviewed the toxicity of nickel to freshwater 
organisms and identified water hardness as the factor most affecting expressed 
lethality. Increased water hardness decreased toxicity (EPA, 1986). It is most 
importcint to measure nickel after the water sample has been acidified to pH 1.5-2.0 and 
filtered with a 0A5 um filter (USEPA, 1986). The derived estimate of nickel (acid 
filtered) above which may be lethal to aquatic life is as follows: 

Nickel NOEC = e^O'^'*^ In (hardness) +3.3612) ^g/^ (EPA, 1986) 


A similar relationship to estimate the level above which sublethal effects may result 
after chronic exposure was developed by the U.S. EPA (1986). It is: 

Nickel Chronic Limit = e^^'^"^^ In (hardness) + 1.6^5) ^g/^ (EPA, 1986) 



Zinc has also been widely studied and toxicity has been reported to vary according to fish 
size, temperature, pH, water hardness and dissolved oxygen (Spear, 1981). Changes in 
zinc speciation affected by pH have also complicated identification of toxic levels of 

Data generated by Bradley and Sprague (1985) showed that zinc toxicity increased as pH 
increased from pH 5.5 to 9. The general slopes of the toxicity-pH relationships were 
similar for the two different water hardness conditions tested which suggested that a 
descriptive model might be developed. The data produced by other authors (Meisner and 
Hum, 1987) was at an intermediate water hardness to those tested by Bradley and 
Sprague (1985) and was used to complete the data matrix for development of a toxicity 
model. Increased water hardness clearly decreased the toxicity of zinc. 

'*I39.3 3.f 

The following model for the toxicity of dissolved (0.^5 urn filtered) zinc appears to fit 
the data sets provided by the two studies: 

Hardness (93.3 e-^-^^ pH) 

LC50 Zinc = mg/L 


The CWQG guideline to protect aquatic life against chronic exposure to zinc is 
0.030 mg/L, which is used as the chronic value in the model. 

TRC Toxicity 

Many experiments have been conducted to determine the toxicity of chlorine residuals 
(TRC) to aquatic organisms. Reviewers of the subject (Brungs, 1973) concluded that 
residual chlorine is acutely toxic at levels as low as 0.01 or 0.02 mg/L, although most 
LC50's reported for fish and invertebrates are as much as 0.08 and 0.3 mg/L, 
respectively. Chronic effects are reported to occur as low as 0.001 mg/L (behavioural 
avoidance), but again, most effects were observed at higher concentrations (greater than 
0.01 mg/L). The majority of data were from studies of chlorine in wastewaters where 
possible additive or synergistic effects from other contaminants (particularly ammonia) 
were ignored and the toxic effects of TRC may even have been overestimated. 

Laboratory toxicity tests conducted with clean dilution water are in fairly good 
agreement, however. Arthur and Eaton (1971) identified the acute LC50 between 0.085 
and 0.15't mg TRC/L for fathead minnows, while the LC50 for amphipods was 0.22 mg 
TRC/L. The chronic threshold values from the same study were 0.0't3 mg/L for 
amphipods (reduced survival and impaired reproduction). Larson et ah (1978) tested 
chloramine toxicity to adult rainbow trout and found no evidence of harmful effects at 
0.05 mg/L, but threshold concentrations for growth of alevins and juveniles were between 
0.01 and 0.022 mg/L. 

Considering all the available data, especially those based on amperometric 
measurements, the acute and chronic thresholds for aquatic toxicity of total residual 
chlorine can be estimated as approximately 0.0^ (lowest LC50 of 0.085 x safety factor 
of 0.5) and 0.01 mg/L, respectively. 



Acute lethal threshold = 0.04 mg TRC/L 

Chronic threshold = 0.01 mg TRC/L 


Ammonia dissociates into molecular (NH-j) and ionic (NH^) forms according to the pH of 
the solution. The molecular form is the more toxic to fish and is therefore the species to 
be monitored to estimated toxicity. 

The relationship between pH and ammonia ionization is: 

(Emerson et al., 1975) 

Fraction of Total Ammonia 
as un-ionized (NH3) 
where pKa = 0.09 + 

The U.S. EPA (EPA, I9&i^) and the International Joint Commission (IJC, 1985) have 
published reviews of ammonia toxicity to aquatic life to develop water quality criteria 
and objectives. These reviews indicate that while temperature and pH control the degree 
of ionization of total ammonia only pH truly affects the potency of the un-ionized 
form. Un-ionized ammonia is more toxic under low pH conditions than under higher pH 
conditions. Lower temperatures may also increase the potency of un-ionized ammonia 
although this relationship is not developed. There has been no indication that water 
hardness influences ammonia toxicity. 

Evaluation of the available ammonia toxicity data by the U.S. EPA (198^*) resulted in the 
following relationship to estimate the toxicity of un-ionized ammonia to rainbow trout. 
Based on concentration-lethality relationships a factor of 0.3 was applied to the LC5Q 
estimate (13C, 1985) to calculate the concentration above which lethality was expected 
to occur. 


96 hour non-lethal NH3 = (0.3) 


1^10 1.03(7.32-pH) 


A similar relationship has been developed by the U.S. EPA to describe chronic protective 
limits for salmonid fisheries. 

Chronic NH3 no-effect level 


1^10l-03 (7.32-pH) 


Phenol (* AAP Measurement Method) 

Phenolic compound concentrations are routinely estimated by the «f-aminoantipyrine 
method which is non specific and will react with any ortho or meta and some para 
substituted phenolics plus the parent compound phenol (mono-hydroxy benzene). Phenol 
is the most common of the phenolics and is generally produced as an intermediate in the 
preparation of other chemicals. Methyl substituted phenols are used as food 
antioxidants, and are present in asphalt runoff, metal cleaning, petroleum refining, 
formed in the manufacture of pharmaceuticals, wetting agents, dyestuf fs and are present 
in domestic sewage (Craig, 1987). Nitro substituted phenols are intermediates in the 
manufacture of organic chemicals and dyestuf fs. 

Review of phenolics acute toxicity indicates that the NOEC levels for dimethyl and nitro 
substituted phenolics is very similar and therefore the same value can be used for all 
those most likely to be found in ambient waters. The most protective non-lethal limit 
for the methyl and nitro substituted phenols was 1 mg/L (Craig, 1987). 

Phenol (* AAP) NOEC = 1 mg/L 

Phenol and 2-methylphenol are an order of magnitude more toxic to aquatic life than 
dimethyl and nitro substituted phenols and therefore selection of the recommended 
criterion of 0.02 mg/L would protect against chronic toxicity for other phenolics (Craig, 



Phenol chronic protection = 0.02 mg/L 

The chronic protection level is within the direct photometric measurement detection 
method of 0.01 mg/L. Chloroform extraction can increase detection limits to 
0.0005 mg/L. 


Pentachlorophenol (PCP) has been detected in the Don River. PCP is a weak acid which 
results in both toxicity and bioaccumulation decreases as pH increases. The U.S. EPA 
(1986) has extensively reviewed the acute and chronic toxicity of PCP and developed pH 
dependent relationships to estimate effect levels for aquatic biota. They are: 

PCP Acute NOEC = e^-OO^^PH) " '♦•^O» ^g/L 

PCP Chronic NOEC = e^-005{pH) - 5.368 ^g/L 

Other Chlorinated Phenols 

The MOE (Craig, 1987) water quality development document reviewed the sources and 
ambient levels of chlorinated phenols in Ontario and cited only a few cases where levels 
exceed the proposed objectives. It is therefore reasonable to conclude based on this data 
that any contributions to the total phenolics level would likely be insignificant. Only 
PCP deserves special consideration. 

Dissolved Oxygen 

Dissolved oxygen while not a toxicant does influence the potency of available toxicants. 
Since most toxicants act on metabolic systems all of which require oxygen for normal 
function and energy transfer (ATP cycle), there is a level of dissolved oxygen in water 
below which metabolic needs will be restricted. 

The U.S. EPA (1985) has reviewed ambient dissolved oxygen requirements of aquatic 
biota and determined that certain levels will affect acute survival and be protective 
against sublethal effects during chronic exposure. 

(* 139.3 3.8 

Survival of many fish species is reduced when dissolved oxygen falls below 3.0 mg/L. 
Salmonid growth and reproduction is impaired when chronic dissolved oxygen exposure 
falls below 6 mg/L. The thresholds (EPA, 1985) are accordingly: 

Dissolved Oxygen NOEC ACUTE = 3 mg/L 

3.3 Estimating Mixture Toxicity 

Toxicologists have long attempted to estimate the toxicity of a chemical mixture based 
on knowledge of the constituents and their Individual toxicities. The theory of toxicant 
interaction has been intensively reviewed (EIFAC, 1987; deMarch, 1987a, b; Anderson and 
Weber, 1976) and no satisfactory alternatives to the strict addition approach have been 
proposed. Current thinking is that while none of the theories will provide a precise or 
reliable estimate of toxicity they may have a qualitative application. 

3.3.1 Model Formulation 

Strict Addition Estimate of Toxicity 

The simplest approach to estimating the toxicity of mixtures is to sum the proportion of 
toxicity expected based on the fraction of the effect concentration present. If the 
summed value exceeds unity (1.0), it is likely that the mixture will induce the lethal or 
sublethal effect estimated. 

Cumulative Toxicity 

I chemical || chemical n 

toxic chemical 1 toxic chemical n 

The first step is to measure the toxicant of concern and divide that value by the 
concentration known to be toxic. This produces what is known as the toxic unit 
contribution for that chemical. The toxic contributions, or toxic units, of each chemical 
will proportionately contribute to the total toxicity of the mixture. 

^^139.3 3.9 

Adjustments to the Model 


Phenolics have a varied interaction with the other toxicants with regard to acute lethal 
effects (EIFAC, 1987). When the calculated phenol toxic unit is less than 0.1 the 
contributory effect is antagonistic and the negative value of the toxic unit should be 
included in the summation. Phenol toxic unit values between 0.1 and 0.3 should be halved 
before inclusion into the summation. Toxic unit values greater than 0,3 can be included 
directly into the summation. 

Toxicity Level 


Phenol Toxic Unil 

L 0.1 

0.1 to 0.3 

G 0.3 


change sign and add 

add one half TU value 

add directly 

add directly 

Dissolved Oxygen 

Because dissolved oxygen influences toxicity only below critical levels it is proposed that 
adjustment of the cumulative toxic unit value be made to allow for potential oxygen 
effects. This adjustment can be easily incorporated for both the acute and chronic cases 
by expressing the ambient dissolved oxygen levels as a fraction of the minimum optimal 
value (eg 3 mg/L for acute; 6 mg/L for chronic). The cumulative toxic unit is then 
divided by the fraction of the critical oxygen requirement to proportionately increase 
the cumulative value. There is no need for adjustment if the critical oxygen value is 
met. When dissolved oxygen approaches zero the cumulative toxic unit would approach 
infinity indicating an exceedingly toxic condition for both acute and chronic impact. 


ambient D.O. is less than critical D.O 



Then: fraction of critical D.O. 

And: adjusted cumulative T 

The Model 

Ambient D.O. 

Critical D.O. 

(3 mg/L acute) 
(6 mg/L chronic) 


Cumulative Toxic Unit 

Fraction of Critical D.O. 

Consider the following environmental conditions for a certain stretch of the Don River: 


Dissolved Oxygen 

= 7.8 

= 180 mg CaCOj/L 

= 12, C 

= 5 mg/L 

The toxic unit contributions for various compounds found in the Don River are calculated 
and given in Table 3.1. Data from the Provincial Water Quality Monitoring Network 
(PWQMN) are not used for total phenols due to indications that is not reliable due to 
methods problems. Rather values measured by this study team for the Don River 
(detection limit) are used in Table 3.1. Based upon the definition of TU, a value of 1.0 is 
a threshold for toxicity. Accordingly, a value of 8.5 for acute response would suggest 
that the mixture is toxic. Calibration of this interpretation with actual test data is 
required to establish confidence In a reference value of 1.0. 

3.3.2 Limitations of the Model 

There are certain limitations to this approach of estimating toxicity. 

o the total toxicity estimate Is only as good as the estimates of toxicity for the 

individual chemicals. This is particularly critical when toxicants are influenced 
by physical chemical conditions which are not well described. 

o the more numerous the number of chemical components that are incorporated 

into the model, the larger the sum of the toxic units is likely to be. Even small 



toxic unit contributions numerically increase the total unit value and may 
increase it above unity and suggest lethal conditions when none are exhibited. 
The opportunity for a false positive (determination of a non-lethal mixture to be 
lethal) estimate increases as the number of constituents incorporated into the 
calculation increases. 

o the inherent lack of precision in estimating the toxicity of mixtures makes the 

probability of differentiating between marginally toxic and marginally non-toxic 
mixtures very low. These mathematical estimates cannot replace actual toxicity 

3.3.3 Data Requirements 

It Is apparent from the proceeding discussion that It Is critical that the proper data be 
used to estimate toxicity. The following summarizes important data components: 

o the pH, temperature and hardness (as CaC03) of the sample must be measured to 

estimate the toxicity of many of the chemical components. 

o only the un-ionized concentrations of ammonia must be used in the toxicity 


o only the dissolved (0.^*5 um filtered) concentrations of copper and zinc must be 

used in calculations. Only acid filtered concentrations of nickel must be used in 
calculations. Total unflltered metal concentrations will produce over estimates 
of toxicity. 

^A Validation of the Toxicity Model 

Unfortunately the model cannot be confirmed with documented toxicity test data. The 
necessary complement of input data which includes chemical measurements and toxicity 
testing on the same water sample are lacking, f>articularly sample hardness which is 
critical to the calculation of metal toxicity. Toxicity test data when published also 
frequently lacks description of solution pH which influences the ionization of ammonia. 

'♦139.3 3.12 

One water sample for the Don River was chemically characterized and its toxicity 
tested. The TU model qualitatively agreed with the test results, but such a database is 
of limited value - many samples need to be tested to determine confidence in the 

Despite the lack of validation, the TU model has substantial value. The model indicates 
the need for measuring cind documenting specific test conditions in toxicity or chemical 
reports. It allows one to assess the potential impact of toxicity upon fish habitat. 

3.5 Applications of the Mixture Toxicity Model 

The input of chemical and physical data (pH, temperature, hardness) will allow the 
resource manager to project how the river water quality might be affected by seasonal 
changes in temperature, pH and hardness. The potential impact of discharged effluents 
or the extent of impact from spill incidences can be estimated with the model to allow 
expeditious direction of remedial measures where possible. 

The simplicity of the described mathematical relationships can also be easily 
accommodated and stored in programable hand held calculators or portable computers 
for on site monitoring of effluent quality. 

Users are cautioned that this model is imprecise and is intended as a tool that will allow 
users to quickly identify which constituents are likely to have biological effects and 
whether the overall biological quality of the river water is potentially impaired. The 
model is best calibrated for individual waters so that after frequent comparison with 
observed impact interpretation of the calculated Cumulative Toxic Units will improve 
the predictive capability of the model. For example some managers may find with 
experience that when the cumulative toxic units exceeds 0.75, samples are likely to be 
lethal to fish while others may find that a value of 1.5 is required to predict lethality. 
Such a range of calculated toxicity is well with the range of model uncertainty. A 
probabilistic simulation exercise would more clearly define thresholds for interpreting 
the calculations of the model. 

^^139.3 3.13 

3.6 Conclusions 

A toxicity model for compounds relevant to management of urban runoff, STP and 
industrial discharges, and the waters of the Don River was developed in this chapter. 
Based upon its evaluation, the following conclusions are drawn. 

1. Acute and chronic values for the contaminants discussed have been computed for the 
Don River under a specific set of temperature, pH, hardness and dissolved oxygen 
conditions and appear in Table 3.1. For the specific conditions selected which are 
representative of the lower river, the calculations suggest that the water is toxic to 
aquatic biota, both at an acute and chronic level. 

2. Measurements of ambient water constituents to predict ambient water toxicity will 
improve the management of watershed utilization and assist in the bracketing of 
distinctly different stretches of river water quality. 

3. Frequent comparison of measured sample toxicity with chemical analysis will allow 
calibration of this model for particular water quality and development of the 
capability to predict immediate and projected mixing zone toxicity based on 

chemistry alone. 

3.7 Recommendations 

Toxicity testing of various influents into the Don River (e.g., North Toronto STP, CSOs, 
separated storms sewer discharges, rural runoff) and of the river itself could be carried 
out to calibrate the interpretation of the toxicity model developed above. 

The toxicity tests should be made at various dilutions until a non acute response is 
achieved, if the various waters indicate an acute response. Chemical characterization of 
the waters should also be made. 

Toxicity tests upon synthetic water samples (i.e., solutions prepared in the laboratory) 
would assist in the the interpretation. Characterization of the role of particulate matter 
in toxicity measurement should also be made in the assessment. 

Special attention to selection of the proper chemical parameters is required. These 
Include pH, hardness, filtered metal concentrations, and total ammonia. 

'J139.3 3.1'» 


Toxic Unit 





Copper (filtered) 

= 0.019 mg/L 


= 0.97^ 


= 1^.75 

Nickel (acid-filtered) 

= 0.013 mg/L 


= 0.006 


= 0.003 

Zinc (filtered) 

= 0.056 mg/L 


= 0.062 


= 1.87 


= 0.25 mg/L 


= 6.25 


= 25 

Annmonia - Total N 

= t mg/L 


= 1.19 


= 2.5 

un-ionized NH3 

= 0.053 



Phenol - Total 

= 0.0005 


= 0.0005 


= 0.0005 



0.072 ug/L 

0.072 =0.00'f 0.072 =0.001 

18.75 12 

Cumulative Toxic Unit 
Adjustment for Dissolved Oxygen 
Final Value 





Factor = 1 =1.2 


k.l Framework for Fish Habitat Management and Assessment of Urban Impacts 

There are a number of alternative approaches to setting environmental criteria against 
which future changes can be assessed or measured and accepted or rejected. The one 
most commonly used is to establish individual criteria for a number of physical or 
chemical parameters of water quality or flow regulation at levels which are arbitrarily 
felt to be "environmentally acceptable". A more contemporary approach has been to 
adopt the ecosystem concept for natural systems in which plant or animal communities 
or individual species are identified as being representative of a set of environmental 
criteria to be maintained or established. This has the advantage of integrating physical, 
chemical and biological elements of the environment toward a measurable and desirable 
endpoint, that of supporting a biological community or species. Physical or chemical 
criteria are not set arbitrarily, but rather relate to the habitat needs of the 
representative species selected. 

This approach is consistent with the recommendations of the Beanlands and Duinker 
(1983) study for the Environmental Assessment Review Office of Environment Canada. 
This three-year study, entitled "An Ecological Framework for Environmental Impact 
Assessment in Canada", represents the most intensive examination of impact assessment 
concepts and methodologies to be carried out in Canada to date. 

In the fisheries management field, a set of Habitat Suitability Index (HSI) models have 
been developed for major North American fish species which incorporate virtually all 
habitat information available in the scientific literature. The purpose of the HSI model 
is to identify important habitat variables for each species which can be used for impact 

«f.1.1 Habitat Suitability Index (HSI) Models 

The HSI model provides habitat information for evaluating impacts on fish habitat 
resulting from water or landuse changes. The impetus for the development of these 
models was the Habitat Evaluation Procedures (U.S. Fish and Wildlife Service, 1980), a 
planning and evaluation technique that focuses on the habitat requirements of important 
fish species. 

'fl39.3 *.l 

HSI models are analogous to other sources of information that address, in general terms, 
the habitat requirements of fish and wildlife species. For example, several com.pilations 
of species databases have been initiated in recent years (e.g., Mason ^a[., 1979; U.S. 
Fish and Wildlife Service, 1980). These databases contain an array of habitat and 
population information. But these databases are descriptive in content. The HSI models 
are unique in that they are constrained to habitat information only, with an emphasis on 
quantitative relationships between key environmental variables and habitat suitability. 
In addition, the HSI series synthesizes habitat information into explicit habitat models 
useful in quantitative assessment. 

The series of HSI models reference numerous literature sources in an effort to 
consolidate scientific information on species-habitat relationships. The models provide a 
numerical index of habitat suitability on a 0.0 to 1.0 scale, based on the assumption that 
there is a positive relationship between the index and habitat carrying capacity. The 
models vary in generality and precision, due in part to the amount of available 
quantitative habitat information and the frequent qualitative nature of existing 
information. When possible, models are included that are derived from site-specific 
population and habitat data. 

Habitat variables in the HSI series fall into one of two general categories - physical 
habitat features (substrates, cover, depth, flow velocity, riffle/pool ratio, etc.) and water 
quality conditions (dissolved oxygen levels, temperature, turbidity, pH, etc.). 

The HSI models are usually presented in three basic formats: 

o graphic, 

o word, and 

o mathematical. 

The graphic format is a representation of the structure of the model and displays the 
sequential aggregation of variables into an HSI. Following this, the model relationships 
are discussed and the assumed relationships between variables, components and HSI's 
documented. This discussion of model relationships provides a working version of the 
model and is, in effect, a word model. Finally, the model relationships are described in 
mathematical language, mimicking as closely and as simply as possible the preceding 
word descriptions. 

'fl39.3 'f.2 

The models present hypotheses of species-habitat relationships, which vary fronn one 
geographical area to another, and must be adapted to the specific environmental 
conditions being considered. As well, the models consider habitat needs for different life 
stages or functions, such as spawning, juvenile rearing or migration. This is illustrated in 
Figure <f.i. 

it.1.2 HSI Model Application 

One of the most effective methods for broadening the ecological perspective of an HSI 
assessment is to use species that represent groups (guilds) of species that utilize a 
common environmental resource. Classification of all study areas species into guilds is 
often a useful step prior to the selection of evaluation species. Figure 4.2 is an example 
of a guild descriptor matrix that summarizes habitat use information for selected 
specis. Use of the matrix in Figure ^.2 shows that bluegill, for example, could be 
selected as representative of a group of fishes that utilize both warm-water 
temperatures and back-waters. The guilds developed from this matrix can be based on 
two or more column descriptors (e.g., cold-water and rocky substrate), rather than a 
single major category, such as temperature. The guilds selected will depend on the 
descriptors necessary to meet the objectives of the HSI application. Guild descriptors 
can be based on tolerances of, or responses to, a particular habitat alteration (e.g., 
turbidity) or on specific requirements for completing the life cycle. 

Some typical habitat variables are listed in Figures 1^.3 and tiA for largemouth bass. 
Using river velocity 0^20 ^^ ^ typical example variable (Figure ^^.3), habitat suitability 
ranges from 1.0 (completely suitable) for velocities of to 0.6 cm/s to complete 
unsuitable (SI = 0.0) at velocities greater than 2.6 cm/sec. Similarly, in Figure li.i^, 
habitat suitability is shown as increasing from marginal (SI = 0.1) for dissolved oxygen of 
less than 2 up to completely suitable (SI = 1.0) for DO of greater than 8 mg/L. In this 
case, the curve is shown in step functions as available data do not provide information 
for a continuous function. 

The final result is a composite set of habitat SI curves with quantifiable ranges of values 
within which the river environment will suit the needs of rainbow trout, or any other 
target species selected. If the species selected is representative of the habitat needs of 
the species community or guild which it represents, the river environment should be 

^^139.3 *.3 

H abitat variables 

Ave. thalweg depth (V^) 

X Instream cover (V,,) 

)ls (V,.) 
Pool class rating (V,,) 

% Instream cover (V. ,) 

X pools (V,,) 

Pool class rating (V,,) 

% substrate size class (V,) 

% pools (V,.) 

% riffle fines (V,.(,) 

Mod el componenti 

% streamside vegetation (V,,) 
X riffle fines (V,.o) 

% streamside vegetation (erosion) (V,,) 
% midday shade (V,,)^— 
% Ave. daily flow (V,.) 

Variables that affect all life stages. 
''Optional variables. 
^Steelhead variable. 


































T3 a; 













•a j2 

S> "^ 


■D 1- 













Large^T'Outh tass 








Spotted bass" 










BliCk cripple 











White crappie 




























Slough barter 








Corrmon carp 










Snall.Touth buffalo 













Channel catfish 













White sucker 












Northern hogsucker 








Striped bass 











Rainbow trout 















Categories fron Hokanson (1977) 
^Categories from Balon (1975) 
Common names from Robbins et al. (1980) 


V,e Maximum current veloc- 
ity at 0.8 depth within 
pools or backwaters 
during spawning (Kay- 
June). (Embryo) 

1.0 - 
0.8 - 



0.6 - 



0.4 - 



0.2 - 



0.0 H 


3 5.0 



Average current veloc- 
ity at 0.6 depth 
during summer. (Fry) 

2.0 3.0 

Stream gradient within 
representative reach. 




Average TDS concentra- 


' V ' ' 


tion during growing 
season when carbonate- 
bicarbonate > sui fate- 




chloride ionic concen- 
tration. If sulfate- 
chloride concentration 
exceeds carbonaie- 
bicarbonate. reduce SI 
rating for TOS by 0.2. 


2 0.4- 


"^ 0.2- 

1 " 


250 500 750 1000 

Minimum disssolved 


oxygen levels curing 
midsummer within pools 

1 0.8 - 

or 1 i ttoral areas. 

A) Frequently < 2 mg/1 

B) Usually > 2 and 

< S mg/1 

C) Usual ly > S and 

< 8 mg/1 

D) Often > 8 mg/1 


•^ 0.2 - 
0.0 - 






pH range during grow- 
ing season. 

A) < 5.0 or > 10.0 

B) > 5 and < 6.5 or 
> 8.5 and < 10.0 

C) 6.5-8.5 

1 .U - 
1 0.8 - 
.?0.6 - 

'^ 0.2 ■ 


generally suited to support all or the majority of these species and their respective food 
chains. The SI (Suitability Index) curves provide criteria against which habitat changes 
related to urban developments or other watershed changes can be assessed or modelled to 
determine whether such changes are within acceptable ranges. They also can help guide 
the nature and type of preventative or remedial actions to be taken to protect or 
enhance aquatic environments for the representative species. In this regard, this 
approach can support the related objectives of assessing and controlling impacts of 
future watershed developments and providing a solid scientific basis for managing the 
fish resource. 

^.1.3 Priority Habitat Variables 

Considering the potential for urbanization impacts on the upper Don River, and the 
present urban and industrial impacts in the middle and Lower Don River, the most 
important aquatic habitat variables include: 

o changes in base and peak flow regimes, 

o water temperatures, particularly in mid-summer, 

o turbidity levels, 

o water quality changes related to urban industrial and agricultural runoff, and 

o quality of fish spawning habitat. 

The selection of priority habitat variables will, of necessity, depend on the fishery 
management priorities for a section of river. If, for example, the lower Don River is 
managed for a self-sustaining smallmouth bass stock, habitat criteria for all life stages 
during all seasons of the year must be considered in the HSI model. However, if 
management is concerned only with a hatchery-maintained adult fishery, in the river for 
sport fishing purposes, habitat criteria need only relate to those seasonal needs of the 
adult fish (water temperature, flow and quality). It is for this reason that a fish resource 
management plan is required for the Don River (see Section 5). 

'f.l.'f Potential Limitations 

One of the potential limitations of an HSI model approach on the Don River relates to 
the limited water quality database available to describe episodic events (e.g., spills, 

^^139.3 UA 

other transiant phenomena) for inclusion in suitability index (SI) evaluation. A second 
limitation is inclusion of toxic effects in the HSI model. A third limitation is adequate 
documentation of habitat variables. 

Physical habitat conditions have been inventoried in sections of the Don River. This 
allows for an adequate SI evaluation of physical factors for purposes of this "framework" 
study. The inventory is inadequate for detailed fisheries management puproses. Long- 
term, multi-season water quality data, however, appear less well-suited. 

In the absence of similar water quality database, the HSI model could be used to establish 
minimum criteria for important water quality variables. For instance, a suitability index 
value of 0.8 for each important variable can be assigned as the minimum level acceptable 
for a particular species. This might apply to criteria such as water flow, temperature, 
turbidity, etc. The achievement of this value for each variable can then be tested or 
modelled to determine its achievability under different development or change 
scenarios. The effectiveness of alternative approaches or remedial activities to achieve 
the desired level can also be assessed. 

The limitations related to aquatic toxicity and spills were removed in this study by 
including them in the HSI model (see Chapter 5). 

ft.2 Selection of Target Fish Species for Don River 

'f.2.1 Approaches to Assessing Target Species 

In the field of fisheries management, the need for using more than one fish species for 
management of a tributary is of concern. The approach used in other local studies of 
selecting a target species as an indicator of a guild of species for a subwatershed unit 
and applying an HSI model is a substantial improvement over present and past practice. 
In developing the District Fisheries Management Plan (DFMP), the approach of target 
species and HSI application has not been used. Rather, experience, knowledge of local 
linkages and creel surveys and general public perceptions are used to establish the plan. 
This results in the DFMP being generic, rather than watershed specific. 


In attempting to assess particular tributaries of the Don River, ground truthing has 
generally not been carried out except for efforts associated with academic work (e.g., 
Steedman with the IBI data; Morris with the influence of hydraulics upon channel 
morphology and fish populations). In manipulating fisheries (e.g., picking up fish and 
transporting above the Milne Dam), immediate practical measures are used; conducting 
the work more scientifically would produce a longer term benefit. 

A process to more rigorously define fish species for management is required. It would 

o an expansion of fish species selected from strictly a cold water/warm water 
basis to at least include the transition zone between cold water regimes and 
warm water regimes; 

further evaluation of the scientific process required to come to a decision on 
species selection (e.g., one species; or more than one species to reflect a 
mixture of fishery community attributes); 

o how to evaluate appropriate species for transition zones in the watershed (e.g., 
between Brook Trout habitat and bass habitat); 

o what size of area, length of reach is required for a particular target species; 

o data required to check and to modify the HSI to Ontario conditions; 

o opportunities provided through two or more species to control and manage 
different fisheries uses, and an opportunity to estimate the costs of 
management for different fisheries use; and 

o use of one species as a target species, and other species as qualitative factors 
in management. 

These considerations should be evaluated in the future. For purposes of this study, the 
target species approach was used. 

139.3 *.6 

if. 2. 2 Criteria for Selecting Target Species 

A target or key fish species provides the basis for establishing desirable aquatic habitat 
criteria for specific reaches of the Don River. A target fish species should have the 
following attributes: 

its habitat requirements should be reasonably well suited to the actual 
conditions which exist in the river reach being considered; 

2. sufficient qualitative and quantitative information should be available on its 
habitat requirements to determine suitability levels for key habitat criteria 
(i.e., calculation of Habitat Suitability Index (HSI) for a given set of habitat 

3. the species should, in most instances, represent a higher trophic level (i.e., 
predator) since these species' habitat needs tend to integrate a broader range 
of habitat parameters (i.e., more complex food chain requirements); 

k. its habitat requirements should be considered generally representative of the 
needs of associated species in the resident fish community (species guild). If it 
is one of the more sensitive species in the fish community, protecting its 
habitat needs should ensure that the needs of associated species are also met; 


It should, in most instances, be a sport fish species which will be recognized as 
having some value and, thus, a priority in resource management decisions. 

The present distribution and general status of various fish species in the Don River was 
discussed above in Section 2. As well, the delineations of upper, middle and lower 
reaches of the Don River was provided above. A very brief and general synopsis of 
possible species is now provided. 


'f.2.3 Possible Target Species 

A variety of possible target species were identified in Chapter 2, based upon existing 
species. Additional species are possible over the long term (50 years), based upon an 
innproved quality fishery. The fish species include the following: 

o Creek chub, because it is one of the four species consistently found in the 
River, particularly the lower river, and has an HSI model. 

o Redside dace for the upper reaches, because it is one of the most sensitive 
species recognized in the area and because it has been assigned a "rare" status 
by the Committee on Endangered Wildlife in Canada. However, there is not an 
HSI model available for it. 

o Other members of the four dominant species found in the river system (white 
sucker, blacknose dace, longnose dace). 

o Smallmouth bass or largemouth bass which occur naturally, for which HSI 
models are available, which are piscivores, which are indicative of a guild of 
fish species and which represent a quality fish to the public. 

o Brook trout which are a native quality cold water fishery resident in isolated 
cold water tributaries of the upper watershed such as MNR lands, and for 
which there is an HSI model. 

o Rainbow Trout which is an indicator of a guild of quality, cold water species 
and which would provide a target for managing a significantly restored quality 
fishery in the Don River. 

Of these species, brook trout, smallmouth bass/largemouth bass and rainbow trout were 
considered further in this study. Other species given above should be reviewed in the 
future and possibly included in a fisheries management plan for the Don River. 

'fng.s *.8 

k.2.3A Brook Trout 

The brook trout is a cold waterfish species. It was endemic to the Don River 
watershed. Its distribution has been severely reduced because of habitat and water 
quality changes associated with agricultural, residential, industrial and urban 
development activities in the watershed over the past century. It is currently restricted 
to isolated headwater tributaries such as the Maple hatchery where habitat conditions, 
particularly cold spring water, remain suitable. 

Because the presence and survival of a natural brook trout population is one of the best 
indicators of the maintenance, or restoration, of a natural and high quality stream 
environment, this species would be an appropriate target species for habitat management 
in selected reaches of the upper watershed. Major habitat criteria for this species 
include cool water temperatures (controlled by groundwater sources and canopy), low 
turbidity levels, adequate instream cover, extensive streambank vegetation to provide 
shading and prevent erosion, stream morphology providing abundance of riffles and pool 
habitats, and gravel spawning beds free of siltation. 

'f.2.3.2 Smallmouth and/or Largemouth Bass 

The smallinouth bass is a warmwater fish species. It occurs naturally throughout the Don 
River watershed. It is one of the species which likely benefited from habitat changes 
which eliminated the brook trout from sections of river, where higher water 
temperatures are now found. This species is generally better adapted to the types of 
stream habitat found in areas of agricultural and extensive residential and industrial land 
use, typical of the present situation in most of the Don River. 

Smallmouth bass is an indicator of a relatively high quality, warm-water stream 
environment. Its presence and survival will ensure that the associated warm-water fish 
community comprising several additional species will also have suitable habitat 
conditions. From a recreational fishing perspective, the smallmouth bass and its close 
relative, the largemouth bass, reach their greatest population and size potential in larger 
pools, ponds and reservoirs on the stream, as is the case at the G. Lord Ross Reservoir. 


Its primary habitat requirements include moderate to warm water temperatures during 
the spring spawning period, good cover in pools and backwaters, relatively low turbidity 
levels and a high percentage of rock substrates. 

'f. 2.3.3 Rainbow Trout 

The rainbow trout is a cold-water, migratory fish species. It is a potential indicator of a 
guild of fish which includes brown trout and chinook salmon. It is an introduced species 
which has become naturalized in all of the Great Lakes and many of their tributary 
streams. It is stocked into Lake Ontario in large numbers, along with brown trout, coho 
salmon and chinook salmon. Like these other migratory salmonid species, the rainbow 
trout could migrate into the lower Don River during the spring and fall of each year, if 
the physical habitat could be restored. Such restoration is a long-term (50-100 a) 
activity. If this occurred, it could provide an important and growing sport fishery to a 
large number of anglers. 

If the rainbow trout was selected as a target species, the two primary reasons would be: 

1. the migratory adult rainbow trout's habitat needs are relatively similar to 
those of the brown trout, coho salmon and chinook salmon, all of which are 
desirable sport fish species for the lower river reaches; and 

2. the rainbow trout has the potential to establish a self-sustaining population if 
it reproduces successfully. This condition exists in other Lake Ontario 
tributaries not far from the Don River, such as Duffins Creek, Wilmot Creek, 
and the Credit River. 

Primary habitat requirements for migrant adult trout include adequate flow levels and 
cool water temperatures during the period of migration and sufficiently large pools to 
hold adult fish. When considering habitat requirements for a self-sustaining trout 
population, additional criteria are added, including cool mid-summer maximum water 
temperatures, rocky and silt-free riffles for spawning, adequate base flows, good 
instream cover for juvenile trout and ample river shading from streambank vegetation. 

^139.3 4.10 

If rainbow trout were to be introduced into the Don River, the first (najor restorative 
action would be to ensure that temperature conditions are suitable. The second action 
would be to ensure that habitat is suitable to migratory adult rainbow trout in the lower 
river, particularly the Keating Channel. 

^.2A Species Selected 

Bass was designated as best meeting the above criteria for the various sections or 
reaches of the Don River. It exists in the Don River. In most of the Don River 
watershed, the present habitat, especially temperature, is condusive only to bass, of the 
three species outlined above. 

Smallmouth bass is a more appropriate target fish species for riverine systems, than 
largemouth bass. Largemouth bass is appropriate for reservoirs such as the G. Lord Ross 
Reservoir, although smallmouth bass also inhabits reservoirs. Accordingly, smallmouth 
bass was designated as the target species for this study. 

The two cold water species, brooke trout and rainbow trout and other warm water 
species outlined in Chapter 2 (e.g., creek chub) should be investigated in future fisheries 
- related, management studies. Brooke trout would be an appropriate target species for 
cold-water, headwater, tributary streams. Rainbow trout would be useful for the 
examining the long-term (e.g., a 50 year) planning horizon. 

k.3 Application of Habitat Suitability Index (HSI) Model for Smallmouth Bass to 

the Don River System 

Habitat Suitability Index models provide a very useful format for examining and 
describing the quantitative relationships between key environmental variables and 
habitat suitability for a particular species. In this section, the HSI model for smallmouth 
bass is applied to existing habitat conditions in the upper, middle and lower reaches, of 
the Don River, and to Massey Creek. A summary of these different reaches determined 
by BEAK fisheries professionals, is given in Table '^.l. 

The Don River habitat database available for determining values which can be assigned 
to each habitat variable in the HSI model ranges from good to poor. For instance, 

ifI39.3 ttAl 


r.g. Maîscy Crerk 

Stream Order 

Mean Gradient (m/km) 

Adjacent Land Us 

relatively flat 
agricultural plair 

urbanizing fringe, 

stagnant lands, 

'iculture, conservation 

lands, recreation 


flat table lands, 

adjacent to rolling 

hills and incised 

valley lands 

urban development 

light Industrial, 
conservation lands 

Major Fish Species 

White sucker, Redbelly 

dace. Pumpkin seed. 

Yellow perch. Mottled 

sculpin. Common 

shiner, Bluntnose minnow. 

Fathead minnow. 

Rainbow darter, Johnny 

darter, Largemouth 

bass, Blacknose dace, 

Longnose dace. Creek 

chub. Brook stickleback 

White sucker, Goldfish, 
Redbelly dace. 
Fathead minnow, 
Blacknose dace, 
Longnose dace. 

Creek chub. 
Pumpkin seed, 
Johnny darter 

deeply incised 

bare valleys; 

heavy urban use! 

urban development 

heavy industrial 

future conservation 


Aquatic Habitat 

1. River Morphology: 

- % riffles 

- % pools 

- % flats 

- % concrete 





2. Vegetation Canopy: 
- % openness 




3. Instream Cover (%) 




K. Substrate 

predominantly sand, 

gravel, cobble, and 

some organic material 

predominantly boulder, 

rubble, cobble, and 
gravel in most reaches 
some organic matter 

in sediments, 

substantial concrete 

lined reaches 

predominantly sand, 

and silt. Concrete 

lined sides. 

Fish Communities 

warm-water species; 
cold, clear-water 
resident species in 
Maple hatchery area 

resident species 

resident species 
seasonal anadromou! 

cold-water species 
possible if adequate 
canopy is restored 

White sucker. 

Emerald shiner (lake 

species), Spottailed 

shiner (lake species), 

Fathead, Blacknose dace, 

Longnose dace. Creek 

chub, Brooke stickleback. 

Pumpkin seed. 

Carp (migratory) 

adjacent parkland 




predominantly rubble, 

cobble, silt; little 

organic material or 

benthic life 

below boulders 

generally devoid 

of fish. 

Species found: 

White sucker. 

Blacknose dace. 

Longnose dace. 

Cheek chub. 


Pumpkin seeds 

Recommended Key 
Species for 
Habitat Preservatior 
or Rehabilitation 

Smallmouth bass. 

Brook trout in 

Maple Hatchery area 

Smallmouth bass 

Smallmouth or Large- 
mouth bass. Rainbow 
trout upon restoration 

Smallmouth bass 

Lower reaches from confluence of East and West Don change from having substantial gradient to being essentially in backwater of 
Lake. The backwaters of the lake are evaluated in the HSI analysis, as the upper reaches of the Lower Don are similar in phys 
habitat to the middle reaches. 

quantitative information on some physical characteristics of stream habitats (stream 
morphology, instream cover, substrate types) is good. This is due to the intensive habitat 
surveys which have been carried out on this river over the past decade by MTRCA and 
MNR, and In academic work. Other habitat data, however, are of poorer quality, 
including information on episodic water chemistry (e.g., spills) and some hydrologlcal 
parameters. Derived data for some hydrologlcal parameters are available from previous 
modelling studies and monitoring data, but need to be synthesized. The synthesis was not 
carried out In this study. For some parameters, values have been derived largely from 
first-hand Inspection of the Don River without benefit of an empirical database. 

The data source for each assigned value for a habitat variable Is identified on the HSI 
tables (Tables ^.2, to ^.5). As well, the potential significance or sensitivity of each 
habitat variable for stormwater management activities on the Don River are assessed on 
each table. Physical characteristics of the river were established from an inspection of 
MTRCA data and the thesis of Morris (1988) and Steedman (1987). Stream chemistry 
were summarized from MOE monitoring data; the Impacts of stormwater runoff upon 
dissolved oxygen were forecast using QUAL2E. Flow related variables were established 
from generic QUALHYMO simulations (BEAK, 1988) and site reconnaissance. Water 
temperatures were assessed based upon MOE/MTRCA monitoring data and QUAL2E 

Tables 'f.2, ti.3, ^M, and k.5 list the habitat variables and their assigned values for 
smallmouth bass In upper, middle, and lower reaches of the Don River and in Massey 
Creek respectively. The resulting HSI value ranges from 0.78, stream habitats of the 
upper Don River to 0.'»2 for the lower river. That is, river habitat Is physically well 
suited to the needs of this species. Important habitat variables to achieve a higher HSI 
value in the Don River would appear to Include the abundance of cover, the degree of 
water level fluctuations, dominant substrate types and turbidity levels. 

A number of habitat variables have been identified as being potentially sensitive to 
stormwater management activities in the middle reaches of the river. These Include 
water turbidity, water temperatures and water level fluctuations (Tables 'f.2 to ^.S). 

Stormwater discharges will have an impact upon the dominant substrate in pools and 
backwater. Good stormwater management will minimize the silt load of the river. 

'*139.3 ^.12 

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However, due to the moderately high hydraulic gradient in the upper and middle reaches, 
water scour will remove most silt. Hence, the effects of stormwater management will 
not be as directly observed. 

Stormwater management will also have some impact upon the oxygen resources of the 
river through controlling BOD. A limited number of numerical simulations of the effect 
of water quality control of stormwater discharges upon the Don River was undertaken. 
The calculations suggest that control of stormwater discharges from separated sewer 
systems (e.g., wet ponds) will have a small effect upon DO because the organics are 
composed of humic substances with low decay rates. More rigorous analysis of DO 
regimes is, however, required to confirm the magnitude of riverine response and to 
include effects of riverine eutrophication. The effect of controlling stormwater and CSO 
discharges should be evaluated in the future. 

Additional data, including diurnal DO (and diurnal temperature) measurements at critical 
spots in the river and levels of DO in a plug of water as the water flows from stormwater 
outfalls would assist in confirming that DO is not presently a significant problem. The 
existing monitoring data (see Supporting Document 5) indicate that present oxygen levels 
are not a major limitation upon fish habitat. 

Of the three variables turbidity, temperature, and water level variations, water quality 
control of stormwater discharges may have the largest impact upon turbidity. This would 
occur if wet ponds were designed to achieve a 80-90% removal of suspended solids. 
Stormwater management using wet ponds may have a substantial effect upon water level 
variations over small spatial scales in small watersheds (e.g., order 1, order 2 streams), 
but a smaller effect upon water level variations in the more main stem of the river. 

Flow control, provided by wet ponds or infiltration devices, will also have a beneficial 
effect upon stream erosion. The ability to decrease the frequency of bank full flow, a 
surrogate for erosion, in natural channels, will decrease erosion and hence siltation. The 
main effect of such control will be in small tributary streams; the effect upon the main 
stem river in the middle and lower reaches (no back water areas) may be minor because 
the relatively large stream gradient assists in preventing significant siltation in many 
areas of the river. 

«fl39.3 «.13 

Stormwater management using wet ponds will have a small impact upon riverine 
temperatures of the Don river (see next section) because it is an open system with high 
temperatures controlled by solar radiation and atmosphere temperatures. The main 
impact would be in ponds and reservoirs where temperatures would be more constant and 
at high values, but have a lower diurnal fluctuation then found in a river system due to 
the thermal inertia of the pond. 

Evaluation of the HSI factors indicates that riparian vegetation (i.e., stream canopy) will 
have the largest effect upon stream temperature. Overhanging canopy for over 3 to 
5 km (Barton et al^ 1985) may be sufficient to maintain a cold water fishery in tributary 
streams (see also Steedman, 1987 re importance of riparian zones). However, once the 
water has heated up, the extent of canopy required is not as clear because in such 
tributary streams, cold springs in groundwater assist in cooling the streamwater, in 
addition to the effects of stream canopy. Significance of Water Temp>erature Limitations for Target Fish Species 

In the simplest terms, riverine temperature determines whether a cold water fishery can 
be maintained for its whole life cycle, whether only as a migratory species during spring 
and fall, or whether only a warm water species is a practical target. Even for warm 
water species, it is necessary to minimize temperature increases above natural levels. 

Excessively high summer water temperatures impose a limiting factor on habitat 
suitability for coldwater fish species throughout most of the Don River. These high 
summer water temperatures are directly related to the extensive removal of riparian 
forests and the beneficial shading effect of riparian forests along the river. Unless this 
habitat parameter can be improved to the level required for cold-water fish species, 
rainbow trout or any other salmonid species will not be capable of maintaining a self- 
sustaining population. 

For example, Table ^.6 lists the habitat variables and their assigned values for a self- 
sustaining rainbow trout population for a river system typical of the lower Rouge River 
or the lower Credit River. The resulting HSI value is 0.00, indicating that present 
habitat conditions are unsuited to a self-sustaining rainbow trout population. However, if 
one examines the HSI habitat variables individually, almost all habitat criteria are at the 

'♦139.3 'iAU 



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high range of suitability for rainbow trout, with one major exception. The maximum 
water temperature for the year (28°C) and the mean maximum water temperature in the 
warm period (2é°C) exceed the upper limits for habitat suitability. This factor alone 
drops the overall HSI value to 0.00. In fact, these cold water species use the river but in 
a migratory sense in the fall. They avoid the warm water conditions by living in Lake 
Ontario during the summer. 

One of the more useful features of the HSI model is its ability to do a sensitivity analysis 
for individual habitat variables. Table ^.7 examines the sensitivity of the rainbow trout 
HSI model to changes in the two water temperature criteria outlined above. As can be 
seen, if maximum water temperatures can be held at 26° and mean maximum 
temperature at 2'f°C, the HSI value increases to 0.72 with all other habitat variables 
remaining unchanged. In this situation, the lower Rouge River or Credit River would be 
rated as having a high suitability for a self-sustaining rainbow trout population. 

The potential temperatures of the Don River on a diurnal basis over the spring-summer- 
fall period should be measured to validate that the values used in Table 'f.ô are 
representative of the Don River. Measurements were made in an extremely hot summer 
(3une 1988) on the lower Don, the lower Rouge and the lower Credit River. Diurnal 
measurements were made on the Rouge with a continuous recorder while spot 
measurements were made over a 2'f-hour period on the Credit River and Don River. 
Modelling analysis of the diurnal temperatures fluctuations were also made for the lower 
Rouge River. For the hottest period in 3une 1988 when diurnal air temperatures ranged 
from 32°C during the day time to 20°C at night time, the riverine temperatures varied 
dlurnally from 28°C to 19-2 1°C in the main stem of the river. This portion of both the 
Credit and Rouge River had substantially more tree cover than the Don River which 
essentially had no canopy. The measurements on the Don River were similar to those of 
the Credit River and Rouge River. Accordingly for the lower Don, the diurnal 
temperature levels are expected to be equal to, or higher than these obtained during field 
monitoring data on other adjacent rivers and modelling simulations upon the same 

Tliis dramatic influence of maximum water temperatures on HSI is in strong agreement 
with the findings of Barton, Taylor and Biette (1985). Their study of W streams in 
southern Ontario, including the Credit, Humber, Bronte and other Lake Ontario 

'*139.3 f.i5 



Maximum Water 
Temperature (^C) 

Mean Maximum Water HSI 

Temperature Ç-'C) Value 

Base Condition 




Scenario 1 




Scenario 2 




Scenario 3 




tributaries, determined that the only environmental variable which clearly distinguished 
between trout and non-trout streams was weekly maximum water temperature. Streams 
with three week, average maxima less than 22, C had trout, while warmer streams had, 
at best, only marginal trout populations. 

The variation in weekly maximum water temperatures in the ^0 streams studied was 
most strongly correlated with percentage of forested stream banks within 2.5 km 
upstream of a site (Barton et aL, 1985). Table 4.6 shows that the percent of tree cover 
on the banks of the lower Credit River and Rouge River averages approximately 20%. 
The more critical variable, the percent of water area shaded during mid-day, is only 5% 
in rivers typical of the Lower Rouge and Lower Credit Rivers. This variable is the 
primary cause of elevated maximum water temperatures In the lower Rouge and Credit 
Rivers, The subject of water temperatures is further addressed (measured, modelled) in 
BEAK (1988) and by Barton et ah (1985). 

Another area of concern to fisheries managers is the major influence on water 
temperature on habitat within the impoundment area and of its discharge on the habitat 
in the river downstream. Candidate reservoirs for consideration in the Toronto area 
include the Milne Reservoir in the Rouge River, and the G. Lord Reservoir in the Don 
River. The increased water retention time in the reservoir combined with the 
shallowness of the basin and lack of any shading results in high mid-summer water 
temperatures in the surface water of the reservoir. This provides habitat suitable for 
smallmouth and largemouth bass but not for rainbow or brook trout. This is a major 
factor in selecting the smallmouth bass as the target species for MSI determination in 
reaches of the Don River downstream of a reservoir. If summer water temperatures 
branches of the Don River below the G. Lord Ross Reservoir could be maintained at 
suitable levels, it may be possible that both the middle and lower reaches of the Lower 
Don would be suited for cool or cold water fish management (rainbow trout). 

The impact of impoundment temperatures upon riverine temperatures were measured in 
the same detailed temperature monitoring program in the Rouge River and Credit River 
described above. Water temperature measurements along the Rouge River during a hot 
spell in 3une of 1988 confirmed that not only do water temperatures in the reservoir 
become elevated, but also water temperatures in the lower Rouge River below the dam 
continue to increase above the impoundment level during the late afternoon period until 

"139.3 «f.lé 

a "riverine equilibrium" condition was attained. This appears to be the result of 
increased exposure to high air temperatures cind direct sunlight along the exposed river 
channel. However, the transition zone from reservoir temperatures to "equilibrium 
river" temperature was only 200 m. Irrespective, the end result is a riverine water 
temperature level which exceeds the maximum limit for rainbow trout. 

Barton, et al (1985) in their study of W Southern Ontario streams concluded the 
following: "our results confirm that temperature is the most significant factor 
determining the presence or absence of resident trout in small southern Ontario 
streams. Control of temperature, and to a lesser extent turbidity and stability of 
discharge, can be achieved through establishment or maintenance of forested riparian 
buffer strips." They further suggest that an unbroken buffer extending 3 km upstream of 
a site need only be 10 m wide to produce a maximum weekly temperature of less than 
22°C. At this maximum water temperature, the HSI for rainbow trout in the lower Don 
River would be good to very good. The fact that a rainbow trout population may be 
attainable on the Don River is supported by the self-sustaining trout population on the 
nearby Dufflns Creek where riparian vegetation appears to be more extensive. 

The watershed management Implication is obvious; forested buffer strips along the 
watercourse of the Don River should be protected where they exist and reestablished 
where they have been removed. Factors to be Included In establishing canopy/riparian 
habitat requirements Include stream width, riparian buffer width and valley width. 

'H39.3 (f.l7 


5.1 Original Smallmouth Bass Model 

The original HSI model for smallmouth bass was developed by Edwards et al. (1983). 
Details are provided by Edwards in his Fish and Wildlife Service (FWS) report. The model 
was developed for riverine populations, but is based primarily on FWS information 
pertaining to U.S. populations in large, wide rivers. 

An outline of the model structure is shown as a tree diagram in Figure 5.1. Values for 
the input variables were presented in Tables 1^.2 to 1^.5. The input variables and functions 
generating and linking the intermediate HSI values are fully described by Edwards et al. 
(1983). Some additional factors such as pool size may be relevant in Canadian riverine 
populations in order 1 and order 2 streams. In such streams, the pool size has small 
dimensions and may limit the size of the bass. 

As indicated in Section ^, the HSI assessment based upon existing physical habitat in the 
Don River and water quality variables included in the HSI model (pH, DO, turbidity) is 
forecast to vary between OA to 0.6. This agrees, in general terms, with site 
reconnaissance of the Don. But it neither agrees with public perceptions of the fishery 
nor with species caught (see Section 2). 

It is the hypothesis of this work that additional water quality impacts due to "toxic" 
components of the chemical matrix of the aquatic system of the Don River are an 
additional limitation to the warm water fishery. This hypothesis is now explored by 
incorporating components of the toxicity model developed in Section 3 into the HSI 
model applied in Section ^. 

5.2 Addition of Toxicity Components 

5.2.1 Components Selected 

Four additional factors were considered for incorporation into the HSI model to evaluate 
toxic and other effects: 

^139.3 5,1 

FIGURE 5.1: 

(Edwards et al., 1983) 

Function Type 

Variable Number and Name 

mnu = menu function 
gem = geometric mean 
usf = user function 
grf = graph 
mea = mean 

1. % River Cover in Pools Backwaters 

2. Minimum DO for Year (mg/L) 

3. Minimum DO in Pools Backwaters 
if. Stream Gradient (m/km) 

5. Mean pH for Year 

6. Maximum Mean Monthly Turbidity (3TU) 

7. Dominant Substrate Pools Backwaters (1,2,3»'*) 

8. Water Temperature in Select Habitat (adult) 

9. Water Temperature in Select Habitat (spawn) 

10. Water Temperature in Select Habitat (fry) 

11. Water Temperature in Select Habitat (juvenile) 

12. Water Level Fluctuations (m) Spawning (1,2,3) 

13. % Cover (boulder, stump, tree, vegetation, rock) 

grf - 
grf - 
grf - 
grf - 
grf - 







o acute toxicity; 

o chronic toxicity of ambient waters; 

o frequency of toxic spills (including CSO overflows); and 

o barrier (or avoidance) effects. 

Of these four components, three were incorporated directly into the HSI model. These 

o chronic toxicity of ambient waters; 
o frequency of toxic spills; and 
o barrier effects. 

Acute toxicity components were not included explicitly because they occur at higher 
concentrations than chronic toxicity components. If a chemical contaminant impairs the 
habitat at low concentrations via chronic effects, the impairment will also occur at 
higher concentrations where acute effects occur. 

Chronic toxicity and the effects of spills were incorporated into the HSI model as one 
additional factor. Spills were included with chronic effects because they may affect fish 
through acute toxicity effects. Chronic toxicity includes such adverse effects as long- 
term mortality or curtailment of reproduction. Critical concentration levels for 
elicitation of chronic toxicity effects were developed in Section 3.0 for copper, nickel, 
zinc, total ammonia, phenol, pentachlorophenol (PCP) and total residual chlorine (TRC). 
Comparison of ambient levels to critical levels in each reach of the Don River provides 
a "toxic unit" contribution for each contaminant in each reach. 

The effect of a barrier was incorporated into the HSI model as a second factor. A 
barrier to fish migration can involve either a "toxic" type "avoidance" reaction in a fish 
species or be a physical barrier. A chemical barrier (such as an STP effluent plume) 
limits the migration of warm-water species through a particular section of the river. 

For the target species considered herein (smallmouth bass), neither type of barrier (toxic 
avoidance; physical) is directly relevant as they can maintain their whole life cycle 
within a reach of the river, once stocked, without migrating upstream. The barrier 
factor would need to be considered in more depth, only as an indicator of such warm 

if 139.3 5.2 

water species as carp who must migrate to lay eggs and rear their young, or as a factor 
for completing a complete ecosystem analysis. 

5.2.2 Addition of Components to the HSI 

The HSI model can be summarized in the form of a tree diagram (Figure 5.1), with input 
variables on the right, the final HSI on the left, and functions which determine 
intermediate HSIs, and their interactions in between. The original HSI model for riverine 
smallmouth bass (Edwards et al., 1983) incorporates habitat variables listed in Tables ^.2 
to i^.U. The additional toxicity variables are diagrammed in Figure 5.2; the barrier effect 
is given in Figure 5.2. Modifications to the model are illustrated in tree diagram form in 
Figure 5.3. As described above, the effects of chronic toxicity and/or spills was added as 
one factor while the effects of barrier was added as a second factor in the HSI model 
(Figure 5.3). 

In inserting the chronic toxicity component of ambient water and the effect of spills 
(assumed as a toxic threshold effect), the component with the largest effect upon the 
suitability index is assumed to be the limiting component (see Figure 5.3). The sum of 
toxic units (CTUSUM) is a new input variable in the modified smallmouth bass HSI model 
to include the effects of chronic toxicity. The calculation of total toxic units for each 
reach is illustrated in Table 5.1. The sum can range from to 20. Any sum greater than 
20 takes the maximum value, indicating that a resident population cannot be sustained 
(Figure 5.2). 

It is hypothesized that the frequency of toxic spills (FTSPILS), rather than the average 
ambient contaminant levels, may limit the success of the population. The annual spill 
frequency is input as an integer variable. Only toxic spills (likely to kill fish) should be 
counted. Ten such spills per year are hypothesized to be sufficient to reduce the HSI to 
zero (Figure 5.2). 

Barrier effects may be important to some local populations which depend for success on 
migration from outside the area (e.g. a spawning migration or recruitment of juveniles 
from more productive areas). Barriers may be either physical (e.g. a dam; a weir) or 
chemical (e.g. a toxic discharge at a river mouth) and may permit some passage through 
the barrier. The impact on the population is expected only if a barrier is in place and the 



Toxicity Fuctions Added to the 

Small Mouth Bass HSI Model 







Sum of Chronic Toxic Units 


l.U — 




il— ^ (B) 

i Effect of 

^ Toxic Spills 










12 3 4 56789 10 11 

Annual Frequency of Toxic Spills 

FIGURE 5.2(C) 

Barrier Functions Added to the 

Smallmouth Bass HSI Model 

1.0 -: 

Degree of Barrier 

SI 0.5 

Requirements for Migration 

FIGURE 5.3: 


Original HSI 








usf: 1-X = intermediate HSI 

min = minimum of two inputs 

prd = product of two inputs 

grf = graph (Figure 6.1 A) 

hst = fiistogram (Figure 6. IB) 

population depends on migration across the barrier. The impact is therefore expressed as 
a function of two variables, BARRIER and MIGRAT, both of which may range from 
to 1. The HSI is reduced by a factor equal to one minus their product. 

The barrier effect due to a large dam or weir which prevents upward migration of a 
species which does not require migration for their life cycle would be assigned the value 
of one for the barrier but a value of zero for its migration requirements. This ensures 
that the barrier component is not a limitation. The barrier due to a chlorinated STP 
plume or chlorinated stormwater discharge can be handled similarly. The acute toxicity 
model (chapter 3) and an empirical SI curve can be used to evaluate the impact of the 
discharge plume as a "barrier" to adults, if one consciously chooses to neglect the chronic 
effects upon the whole life cycle. The acute toxicity model can be used to estimate a 
barrier effect (e.g. 0.5). If the smallmouth bass (as an indicator of a migratory warm- 
water fishery) should be in the zone of the STP plume or chlorinated stormwater 
discharge, the migratory factor is set at one, resulting in an over SI for the barrier 
component of 0.5. 

5.3 Impact of Toxicity, Spills and Barriers Upon the HSI 

The effect of the different chemicals in the river on toxicity and the frequency of spills 
assumed for each zone of the Don River is given in Table 5.1. The contribution of 
toxicity from the different chemicals are based upon concentrations given in Table 5.2. 
The impact of these components upon the unmodified HSI values are given in Table 5.3. 

The chemical concentrations (Table 5.2) for the Middle and Lower Don represent a 
frequency of being exceeded of approximately 10%, based upon PWQMN (Provincial 
Water Quality Monitoring Network) and EMP (Enhanced Monitoring Program) 
measurements. The concentrations in the Upper Don have been assumed to be similar to 
in magnitude, but smaller than those of the middle Don, in the absence of monitoring 
data in the upper reaches. Metals estimates are taken as dissolved at these levels. 

The HSI in the upper and middle reaches is reduced by the same amount due to the 
inclusion of toxicity (Table 5.3), The main contributors to this toxicity are the effects of 
copper, zinc and ammonia upon chronic toxicity. Spills have a larger potential impact in 
the middle reaches than in the lower reaches but due to the assumption of a limiting 

'^139.3 5A 

o o 

VO (VJ f^ — > 

_U ^ 



Copper (dissolved) 

Nickel (dissolved) 

Zinc (dissolved) 





0.019 mg/L 

0.013 mg/L 

0.056 mg/L 

0.053 mg/L as N 

0.0005* mg/L 

0.072 mg/L 

0.25 nag/L in lower river; 

0.0 in remainder of river 

Based upon one-half detection limit of 0.001 mg/L. 



HSI Model 
and Scenario 


HSi in Reach 



Original HSI Model 

o no toxicity component in model 




Modified Model 

o (includes toxicity and spills 



Toxic units and spill frequencies as per Table 5.1 

"toxic component", chronic toxicity has the largest effect in both reaches. The 
contribution of ammonia to sublethal (chronic) toxicity requires further research as the 
values assessed are found in many urban rivers and even rural ecosystems. The ammonia 
values measured as representative of rural ecosysteins may have resulted from hydrolysis 
of organic nitrogen in the sample bottle during sample transport and storage in the 
laboratory before analysis. Accordingly, such ammonia values may be high. 
Measurements of copper and zinc levels in the upper watershed are required to confirm 
the toxicity evaluations given in Table 5.1 for the upper watershed. 

The HSI in the lower river decreases to completely unsuitable levels due to sub-lethal 
toxicity (Table 5.3) in comparison to the upper and middle reaches of the Don River. 
Spills also have a significant effect (SI = 0.1 for spills of 10 per year) but the limiting 
component is chronic toxicity. Total residual chlorine in the STP effluent contributes 
over 90% of the toxicity in the lower river. 



6.1 Variables Evaluated 

Habitat variables used in HSI models for the target species, smallmouth bass in the Don 
River are listed in Tables it.2 to ^.5. Of the variables listed, six are considered as being 
of primary importance with regard to the potential effects of further urbanization in the 
headwaters, stormwater management throughout the watershed and management of the 
STP and CSO's in the lower watershed. These are: 

o changes in base and peak flow regimes, 

o water temperature, 

o turbidity levels, 

o bottom habitat, 

o chronic toxicity, and 

o spills. 

Each of these is considered in the context of existing conditions and the effect of control 

6.2 Predicted Effects for Non-Toxicity Components 

6.2.1 Flow Regime 

In general, urban development within a watershed is expected to influence both the peak 
and base flows more than the average stream flow. From a fisheries habitat perspective, 
it is the mid-summer and mid-winter base flows which are often critical to fish 
populations inhabiting streams. 

In order to provide a suitable database for HSI analysis of the potential effects of urban 
development in the upper watershed, a continuous simulation method for hydrologie 
modelling was required. Calculations made by QUALHYMO in its application in the 
Rouge River, were extracted generically and used here to generate data required for HSI 

'f 139.3 6.1 

Model calculations for the complete urbanization of a rural catchment, were available 
for the following hydrologie parameters: 

o average daily flows for wet, dry and average years (for whole year and summer 

o flow, water depth and velocity-duration curves (for annual, April to 15 May, 
April to September and June to August periods); 

o three-week high flows for various return periods (for summer and fall periods); 

o seven-day low flows for various return periods (for summer and winter 

Salient results pertinent to the HSI analyses as follows: 

o average daily flows are increased in areas downstream of urban development. 
This applies in wet, dry and average years for either the whole year or for the 
critical summer period. The largest increases occur in dry years when urban 
water uses, such as watering of lawns, washing cars, etc., would appear to 
augment low natural base flows; 

o a similar situation exists for the three-week high flow, where urban 
development scenarios substantially increase peak flows. This would appear to 
relate to a more rapid run-off in urbanized areas; and 

o seven-day low flows are also increased after urban development. This would 
appear to result from augmentation of base flows by urban water uses. 

All of the above simulations assume that no special stormwater management facilities 
have been incorporated into the development scenarios. Use of small stormwater ponds 
would have an effect on these results, mainly related to an alternation of values for 
short-term peak flow rates, an effect upon the frequency of bank-full flow and a small 

effect upon seven-day low flows, 

m39.3 6.2 

From the perspective of fisheries habitat, the broad conclusion would appear to be that 
critical base flows during the summer and winter periods would not decline with the 
urban development scenarios being examined. On average, low base flows may even be 
increased somewhat with urban land use in the main stem of the river system. The 
increase in base flow rates over the past two decades is observed in water flow 
measurement records of the Water Survey of Canada. 

This conclusion, however, must be significantly modified for small tributary streams. 
Low flow may not change in the Don River tributaries due to canopy removal because 
little canopy remains in most streams. However, low flow is expected to decrease in 
small tributaries due to the decrease of perviousness associated with urbanization. 

The effect of the above alterations on HSI values outlined in Section 'f.O is negligible for 
smallmouth bass. These alterations would be more important for rainbow trout or brooke 
trout, if they were the target species because they would be more adversely affected if 
flow regimes were altered. However, potential increases in base flow are, on average, 
too minor to increase significantly the HSI value. 

6.2.2 Water Temperatures 

Water temperatures in the Don River are already too high for cool or cold water fish 
species during the summer period. This is the direct result of removal of the riparian 
forest canopy along much of the middle and lower river. 

From a fisheries habitat perspective, urban development or redevelopment should not 
further affect water temperatures negatively, unless further removal of tree canopy 
along the river banks also occurred. The rationale for this statement is as follows. The 
G. Lord Ross Reservoir has a significant effect on water temperatures in the West Don 
River through summer heating of surface waters in the reservoir. Urban activities in 
areas above this reservoir would not cause significantly higher water temperatures in the 
reservoirs than already occur provided that no industrial discharges of heated water are 
permitted. Thus temperature regimes in the river below G. Lord Ross Dam would be 
essentially unaffected by urban activities above it. On the East Don River, this reservoir 
effect does not exist. 

'^139.3 6.3 

Mitigating and restorative efforts should be directed at enhancing the riparian forest 
canopy in order to reduce water temperature and stabilize stream banks. Headwater 
tributaries (e.g., Maple District Office Area), where forest cover remains adequate to 
keep summer water temperatures low enough for brook trout, should be particularly 
safeguarded in this respect when development plans encroach on these areas. 

The impact of further urbanization or urban redevelopment upon temperature 
components of the HSI for smallmouth bass will be small because the previous land uses 
(agriculture in the upper reach; urban land uses in the lower river) have the same 
temperature impacts. This is principally because this habitat variable (temperature) has 
already been degraded and should be the focus of rehabilitative measures. Remediation 
involving restoration of canopy will be the principle means for improving water 
temperatures. Stormwater control by wet ponds will have a significant impact upon cold 
water streams; they will have a minimal impact under present conditions in the Don 
River due to the ambient warm summertime temperatures. 

With substantial improvement (over the long-term) in summer water temperatures, the 
lower Don River may attain a relatively high HSI value suitable for a cold-water target 
species such as a hatchery-maintained, rainbow trout. Attainment of such temperature 
conditions are the minimum requirement if a resident cold-water species is adopted in 
the future by agencies such as MNR or MTRCA as a target species. Only modest 
improvements may be required for temperature, if a migratory cold water species is 
adopted, as their requirements for cool temperatures are more frequently met during 
their normal periods of migration in the spring and fall. 

6.2.3 Turbidity 

Increases in turbidity are often associated with changes in land use, particularly where 
agricultural or construction activities and bank scour occur. Pertinent conclusions put 
forward in other studies or developed in the above HSI analysis include the following: 

1. turbidity in stormwater from urban land uses likely would not exceed that 
presently occurring from agricultural land uses in the Upper Don River 

watershed, at least not in mature, steady-state urban systems; 

if 139. 3 6.<f 

2. the potential exists for major short-term increases in erosion and turbidity 
during construction periods if effective preventative measures are not 

3. wet ponds and other control options will decrease turbidity levels. This will 
not have a marked effect upon the bottom habitat of much of the middle and 
lower reaches of the Don River due to scour resulting from the moderate 
hydraulic gradient; and 

'^. present turbidity levels do not have a substantive effect upon the HSI values of 
smallmouth bass. 

On the West Don River, the G. Lord Ross Reservoir tends to function as a sediment trap, 
with the result that higher turbidity events above the reservoir tend to be moderated 
before release of this water to the lower river. This would tend to provide some factor 
of safety for turbidity levels in the lower Don River, and help to protect habitats against 

On the provisions that construction activity would not occur within the floodplain of the 
river and that suitable erosion prevention measures were employed (wet ponds, sediment 
traps, etc.), turbidity-related effects should have a minimal influence on the HSI for 
smallmouth bass in the remainder of the Don River, particularly in the main stem of the 

Significant improvement in fish habitat will, however, be observed in small tributaries 
with low stream gradient if water quality control is practiced by wet ponds. This will 
occur by controlling the discharge of suspended solids to the tributary. Some effects 
upon the frequency of bank-full flow and hence upon stream erosion may be observed, but 
the magnitude of this réponse was not calculated in this study. 

6.2. if Bottom Habitat 

Urban activities and water quality control will have an indirect impact upon bottom 
habitat. The potential effects include: 

«f 1 39.3 6.5 

1. Siltation; 

2. Change in the size distribution of rubble, cobbles, and stones; and 

3. presence of suitable organic matter as food for the food webs and hence fish. 

Urban activities have a direct effect through construction of concrete lined channels to 
provide hydraulic capacity for flood flows, and of weirs or dams which prevent fish 

Of all these activities, the impact upon organic matter in the bottom habitat and 
channelization are the most severe. As noted above, loadings of suspended solids, erosion 
of banks and their control will not have a substantial effect upon much of the river due 
to scour associated with the river gradient. Similarly, the size distributionof 
rubble/cobble will be affected less by flood flows and more by geological factors which 
control their source and quantity in an urban environment. 

The presence of organic matter is not assessed in the HSI model. Rather it is an 
essential biological factor which is included in a second index, the index of biological 
integrity (IBI), discussed in Chapter 8. 

Concrete lined channels and other channelization projects in the Don River (riprap in 
small tributaries; terrifix brick, gabben baskets) are one of the major limitations of the 
HSI, particularly in such reaches as the West Don. Their replacement over the long term 
with bottom designs which provide for bank stability and hydraulic capacity during flood 
flows but which allow cobble sand rubble to accumulate and vegetation to grow through 
the bed material, will significantly enhance bottom habitat. 

6.3 Predicted Effects of Control of Chronic Toxicity and Spills 

Tables 6.1, 6.2 and 6.3 show the effects upon aquatic toxicity and HSI values for each 
reach of the Don River, of management scenarios, based on the overall modified 
smallmouth bass model. Barrier effects were not considered important since this 
population does not depend on migration. However, toxicity factors are very important. 

f 139.3 6.6 






































flJ 2i o 

> <«•;: 
^ o o 

— > — . o 
•^ d ° 

Ou U 

e iî .s 

— • <N r^ 



HSI Model 
and Scenario 

HSI in Reach 




Present Conditions (includes 
toxicity and spills components) 



Control Measure 1: Treatment of 
STP discharge to 0.02 mg/L TRC 

Control Measure 2: Removal of 
chlorination in STP effluent 


Control Measure 3: Chlorination 
of stormwater to achieve swimming 
standards in River 




Toxicity Units for 


1. Toxic Units Without 

Management (Table 5.1) 
Except that the STP 
Effluent is dechlorinated 
to 0.02 mg/L TRC 




2. Nitrification of STP 
effluent (80% removal 
of ammonia) * 



3. 50% removal of heavy 
metals ♦ 




Nitrificiation of 50% of 
STP effluent and 50% 
removal of metals * 




Control of North Toronto STP effluent to give TRC of 0.02 mg/L levels is assumed. 

6.3.1 Control of TRC Components of Aquatic Toxicity 

The control of chronic toxicity was first evaluated by targetting the key component of 
chronic toxicity in the lower river - total residual chlorine from the STP; and examining 
the impact of disinfection of stormwater by chlorination. Three schemes were 
evaluated. The effect of these schemes upon toxicity units are summarized in Table 6.1 
(Columns 5, 6, and 7, respectively). The effect of these schemes upon the HSI is 
summarized in Table 6.2. 

The three schemes are: 

1. Reduction of TRC in the North Toronto Plant effluent by dechlorination to an 
effluent discharge of 0.02 mg/L TRC (see Column 5, Table 6.1). 

2. Cessation of chlorination at the North Toronto Wastewater Treatment Plant 
(see Column 6, Table 6.1). 

3. Disinfection of stormwater by chlorination to achieve swimming standards. 
This is assumed to result in a TRC level of 0.25 mg/L throughout the middle 
and lower reaches of the Don River basin (see Column 7, Table 6.1). 

The assessment of this third scheme is used to assist in establishing the potential impact 
of this disinfection alternative. Disinfection of stormwater by chlorination without 
subsequent dechlorination is not under active consideration due to the impact upon 
fisheries; rather ultraviolet irradation is the main method evaluated in the Summary 

A management scenario involving dechlorination of the STP discharge to 0.02 mg/L TRC 
as outlined in Table 6.1 would probably not be quite sufficient to permit long-term 
maintenance of a resident small mouth bass population (Table 6.3). The remaining 
residual chlorine, and two other toxicants, ammonia and copper, are primarily 

The removal of any chlorine residual from the STP effluent by cessation of effluent 
chlorination may provide a habitat which is marginally suitable (HSI = O.Qit). With total 

'H39.3 6.7 

removal of chlorine residual, the frequency of spills limits the index to the value of 0.0'». 
The value could approach 0.1 with reduction of spill frequency to 8 spills or less per year. 

Chlorination of stormwater discharges in the middle reach of the Don River would 
clearly have an adverse impact on smallmouth bass F>opulations (Column 7 of Table 6.1). 
If residual chlorine levels comparable to those in the lower Don occurred in the middle 
river, resident smallmouth bass would probably be eliminated in the middle reach of the 

6.3.2 Control of Other Components of Chronic Toxicity 

It is useful to note, as well, the potential impact of other management options upon the 
aquatic toxicity of the river. The effects of nitrification of the STP effluent and 
removal of heavy metals in stormwater runoff is given in Table 6.3 and compared to 
present conditions, assuming that the North Toronto STP is chlorinated to 0.02 mg/L 

residual chlorine levels. 

Nitrification of the STP effluent (80% removal of ammonia) will have a substantial 
impact upon the toxicity, if TRC control were achieved (see Table 6.3). However, it 
would appear from Table 6.3 that control of toxic heavy metals are equally important to 
control of ammonia in the upper and middle zones of the river. 

Wet ponds or their equivalent have been concluded to be a key method in the "Don River 
Strategy" for improving water quality in the river system due to stormwater discharges. 
Removal of 50% or more heavy metals (see Table 6.3) should bring the habitat as 
expressed by the toxicity modified HSI model to a level where chronic toxicity is less of 
a limitation to the suitability of the river for maintaining a healthy fishery. 

6.1* Summary of Modelling Calculations 

The potential effects of further development in the headwater areas of the Don River on 
flows, water temperature and turbidity in lower river sections suggest that HSI values for 
the target fish species would not be significantly affected in the lower river by such 
urban developments. In the case of water temperature, and to a lesser extent turbidities, 
this is due to the fact that conditions already range from being somewhat degraded to 
severely degraded in comparison to natural background conditions. 

'+139.3 6.8 

This is not to suggest that further urban development in general would have no effects on 
habitat suitability for sinallmouth bass. In fact, urban development if properly 
controlled, and redevelopment create opportunities for enhancing present habitat. 

Urban development in headwater areas will degrade present streams significantly, but it 
also provides possibilities for improved habitat if properly designed. The improvements 
are associated with reduction of suspended solids and nutrient inputs from present open 
fields associated with plowing and the resultant overland erosion. Degradation will occur 
due to increased stream erosion associated with flow indicators such as the frequency of 
bank-full flow, stream channelization projects, removal of existing sparse canopy, 
increased frequency of spills, and an increased loading of toxicants such as heavy metals. 

Several issues related to fish habitat management and toxicant management from the 
impacts of urbanization and the potential opportunities for environmental enhancement. 
Following are a number of issues or concerns which should be addressed: 

1. The Habitat Suitability Index model is a resource management and planning tool 
which holds considerable promise. However, rather than only apply it to the average 
of a broad range of habitat variables over extended sections of the watershed (i.e., 
upper reaches, middle reaches), it would be a far more effective tool applied to 
individual tributaries where the specific effects of proposed development and 
restoration projects could be assessed against stated and quantified habitat 

2. Urbanization imposes other environmental risks which are difficult to quantify or 
predict and which are not presently incorporated into HSI models. Two particular 
risks include spills, and urban chemicals. The incidence of accidental spills on 
roadways, at service stations, or at industrial sites increase markedly with 
urbanization. The use of many herbicides, pesticides, fertilizers and other chemical 
agents is more intensive in urban areas. This imposes water quality stresses on 
receiving streams. 

The effect of spills and toxic discharges was incorporated into the HSI model in this 
study. The results indicate that these components decrease the habitat suitability 
particularly in the lower reaches of the Don River from the fair range to essentially 
non-existant. A toxic material entering the river whether from normal stormwater 

'fl39.3 6.9 

runoff, STP discharges or spills, rapidly reduces the HSI value to 0.00 for any 
sensitive fish species. 

Further work is required to validate the relative significance of physical habitat and 
toxic factors predicted by the modified HSI for smallmouth bass. 

Intensively urbanized watersheds, such as the Don River and Highland Creek, do not 
support habitats suited to target fish species such as smallmouth bass. While 
individual urban development projects do not appear to be responsible for major 
habitat deterioration, the incremental and cumulative effects of all urbanization 
activities likely have a profound effect on many facets of the stream ecosystem. If 
there are natural limits to urbanization beyond which river systems can no longer be 
managed as useful and productive- resources, these should be taken into account in 
developing a total watershed land use management plan. 

In the case of the Don River watershed, particularly the Lower Don, the evidence 
appears qualitatively to be sufficient to indicate that these natural limits have 
already been exceeded. 

'fl39.3 6.10 



The response of fish habitat to water quality control requires that models be available to 
predict the response of water flow, water depth, suspended solids concentration, water 
temperature, dissolved oxygen and aquatic toxicity to control efforts. Models are 
available to predict, in a reasonable way, the above-noted response variables and the 
chemical concentrations which cause aquatic toxicity. When applied as indicated 
previously in Chapters 5 and 6, the response of fish habitat to water quality control 
efforts can be evaluated quantitatively. 

One major link which to date has been missing is the quantitative tools necessary to 
calculate the response of aquatic toxicity and its effect upon fish habitat. This link has 
been established in this study. This link is now compared to mechanistic models for fish 
uptake of contaminants to show where future research and modelling directions may 
improve the link of aquatic toxicity to fish habitat. 

Scope of Chapter 

This chapter places existing models for contaminant uptake by fish into a pathways 
perspective. It then uses this perspective to show a few of the potential shortcomings of 
the Toxic Unit model approach but also to show why it is a useful tool for the forseeable 

7.1 Environmental Pathways 

An environmental pathways approach to contaminant transport is a method increasingly 
used by academic, scientific and regulatory agencies to assess the impact of contaminant 
releases to the environment upon fish and biota. Basically, it is a steady-state, mass 
balance approach to calculating environmental concentrations, concentrations, or body 
burdens in fish and biota, and levels in human beings, given release rates from various 
natural and cultural sources. 

'H39.3 7.1 

An environmental pathways block diagram is given in Figure 7.1 relating the flow rate of 
water discharged, and the mass discharge rate of contaminants from various sources 
(households; hospitals, universities and other institutions; watersheds e.g., stormwater 
runoff; atmospheric; leachate) to concentrations in surface water (including rivers) and 
aquatic sediments, concentrations in fish and other terrestrial biota, and the resultant 
concentration in human beings. 

In the case of cancer and other human impacts, the accumulation rate of contaminants in 
humans can be related to the potential risk to developing cancer from carcinogens (such 
as arsenic, PAH's, PCB's, dioxin) or from ionizing radiation (e.g., radionuclides such as 
1-129, Cs-137, Ra-226, etc.). 

An overview of the mathematical model which uses the steady-state mass balance 
approach to predict the chemical contaminant burden of elements in fish or humans due 
to contaminant releases to the environment, is given in the appendix. Relevant aspects 
of the model are summarized herein for the following purposes: 

1. to show how the Toxicity Unit Index approach used in this study is based upon 
mass balance principles and toxicity concepts; and 

2. to detail corrections necessary to total metal concentrations measured in the 
environment for use in the toxicity model. 

7.2 Models for Fish Uptake 

7.2.1 Bioconcentration Factor Approach 

The chemical burden of these elements in fish can be assessed from measurements of fish 
tissue and checked using the bioconcentration factor (BCF) approach. The BCF approach 
is based upon empirical relationships between waterborne concentrations (or sediment 
concentrations) and fish tissue concentrations obtained in other aquatic systems. 

'♦I 39.3 7.2 

The bioconcentration factor (BCF) is defined as: 

mg/kg in edible parts of fish 

BCF = (7.1) 

mg/kg in water or sediments 

- (see Figure 7.1) 

Values for BCF's are tabulated in standard references in the scientific literature. 

Use of the BCF provides an order of magnitude estimate of the chemical burden in fish, 
as there are various factors causing variation in the estimates including bioavailability of 
metals in the water or sediments. Monitoring data narrow the uncertainty but must be 
carefully assessed where the fish's life cycle is spent in different water bodies (e.g., the 
Don River, Toronto Harbour, Lake Ontario). 

The BCF approach is an equilibrium approach in which the concentration in the fish is 
assumed to be instantaneously at equilibrium with the water concentration. This implies 
that the fish concentration responds to the typical half order of magnitude concentration 
variations observed during and after storm events. Clearly, this does not occur; rather 
the fish reaches a dynamic steady-state with the environment dependent upon the time 
scale of ambient concentration variations and the kinetics of uptake. 

7.2.2 Kinetic Approach 

A pathways diagram for movement of contaminants into and out of fish is given in 
Figure 7.2. The basic mass balance on the uptake and release pathway is 


kj C^ - k2 Cp - k3 Cp (7.2) 

«♦139. 3 7.3 


Fish Pathway Kinetics 


(a) Pathways 




i I I I I I I I I I I I I I * 

7 14 Time (Days) 

(b) Determination of BCF Value 

Body 3 —I 



I I I I I I I I I I I I I I ' 

14 Time (Days) 

(c) Relationship of "Chronic Body Burden 
With Acute Body Burden" 

FIGURE 7.2 (Cont'd) 

Body 3 



(d) Uptake Curve for a Variety 
of Water Concentrations 

— — — CJ= 

Body 3 - 





/ ^ ^ 





rr I 1 1 1 1 1 1 1 

1 1 1 1 1 1 

(e) Uptake Curve for Several 
Narcotic Organic Chemicals 

where: Cp - fish concentration (molar, i.e., moles/L) 

C^ = the water concentration (molar) 

kj = uptake rate constant (d"^) 

k2 = elimination rate constant (d"M 

k.j - decay rate constant (d"^) 

If decay is negligible, as it is for most inorganic chemicals and many organic chemicals, 
the general kinetic equation is: 

Cp = C^ . BCF (1 - exp ( - k2t)) (7.3) 

where: BCF = ^i/^2 

This is called the general, one-compartment open model operating under first order 
kinetics (McCarty, 1987). Its assumptions are often not stated in the literature. They 
are as follows. It assumes that water concentration is constant. It assumes that the fish 
concentration is zero, initially. 

7.2.3 Relationships Between Bioconcentration and Toxicity 


A curve predicted by the model for accumulation of a substance in fish is given in 
Figure 7.2(b). Under the given test conditions, the steady-state concentration in the fish 
is 3uM (micromolar). The time to approach equilibrium is approximately 7-10 days, 
which, as indicated in Equation 7.2, is determined by the elimination rate constant, k2. 
The actual magnitude of bioconcentration is given by the ratio of the two kinetic 
constants, k|/k2. 


A curve for the uptake of organic chemicals such as narcotics in a toxicity test is given 
in Figure 7.2(c). The graph indicates that for the particular narcotic applied to rainbow 
trout, the body burden at which an acute response (C^) in fish is observed, is 
approximately 3.5 mM (millimolar) and that the body burden at which a chronic response 
(C^) is observed, is approximately 0.6 mM. 

Two test waters and the resultant body burdens predicted by the contaminant uptake 
model (Equation 7.2) are also indicated in Figure 7.2(c). For one water. sample whose 
steady-state body burden (C p j) is approximately 6 mM, the fish attains the acute body 
burden within 'f days and hence would fail the acute toxicity test (i.e., it would die in the 
standard 96-hour LC50 test for rainbow trout). For the second water sample whose 
steady-state body burden (C p j) is approximately 0.5 mM, the fish would pass the acute 
toxicity test, but start developing chronic toxicity effects between 7 and ft days. Such 
chronic effects include: 

o change of skin colour; 

o swimming in a disorientated manner; and 

o other physically observable stresses. 

Sketched also upon Figure 7.2(c) is a postulated set of limits for the 95% confidence 
interval for the tolerance distribution curve (a type of probability distribution function 
(PDF)) of fish to the acute toxicity test. These limits suggest that the lower limit of the 
"acute" response of fish in the terms of mortality are within the same range of chronic 
toxicity. An alternative interpretation is that errors in the estimates of the short-term 
acute test fall, at longer time frames, within the same range as the upper limit of the 
chronic test, a level where other effects such as disorientation of fish can also act to 
magnify the effects of low levels of contaminants. 

The lower threshold curve, C p -r , also indicates that if sufficient time passes, the 
integration of low levels of contaminants in water can still cause stress to fish, even 
though "explicit" acute body burdens are not attained. This whole technical area is, at 
present, contentious and requires further research to validate/challenge the research 
given in Figure 7.2(c). 

Effects of Different Water Concentrations 

The effects of three different water concentrations upon body burdens are given in 
Figure 7.2(d). The highest concentration, C^ , causes acute toxicity within 1-2 days 
while the second level, C^ , causes an acute response within tt days. The third 
concentration level, C^ , does not cause an acute response within it days but may cause 
an acute response in 7-1 'f days, given the range of the tolerance curve indicated in 

'>139.3 7.5 

Figure 7.2(c). The third curve, C^ , would cause a chronic response because its body 
burden at iO-I't days, 1.2 mM, is above the "chronic body burden", indicated in 
Figure 7, 2(c). 

7.2.^ Recent Advances in Toxicity Testing 

Substantial investigations into the theory and science of toxicity testing have been 
attempted in the past few years (McCarty, 1986, 1987a, b; McCarty et al^ 1989; 
Abernethy et^ a_L, 1988). However, most of the recent work in the field has advanced the 
protocols for testing, without relating the test results to water concentrations or to body 
burdens. The above section outlined some of the theory of effects of toxicity and 
bioaccumulation. This section presents the recent advances and their relationships to 
typical test results. 

The following statements outline the recent advances and the interrelationships: 

1. Toxicity and bioaccumulation (bioconcentration) are related through the model 
given above (Equation 7.1). The best predictor of toxicity is body burden; 
however, this response variable is rarely measured. Water concentration is 
usually measured. Only when the BCF and the kinetic constant k2 are known, 
or when body burden is measured over time in the toxicity test, can the 
concept of body burden be used to assess toxicity. 

2. There is a need to homogenize toxicity testing and bioaccumulation 
measurements, as both give similar information (based upon the next point, and 
the kinetic model). 

3. Experimental evidence is evolving that body burdens, which cause acute 
responses, have the same value for similar modes of action. This evidence is 
limited, at the moment, to narcotics, as they are the only ones tested so far. 
The evidence suggests that for narcotics, acute toxicity is observed in the 
range of 3-6 mM and that chronic toxicity is observed in the range of 0.1 to 1% 
of these levels. 

«♦139. 3 

The following typical ranges of acute toxicity (McCarty, 1987) have been 
observed for body burdens for the following compHaunds. 

Body Concentration 



(in M /kg) 















Approximately 1 









5. When a group of compounds which have the same mode of toxic action (e.g., a 
narcotic) achieved a cumulative body burden in ** days which is greater than 
the acute body burden, an acute response is seen in the fish. 

Cumulative Effects of Toxicity 

The latter point above is illustrated in Figure 7.2(e) for narcotics. The body burden 
curves for four compounds (Cp , Cp , Cp , Cp ) are given. The individual body burdens 
(at t = I'f d) are 0.5, 1.0, 1.5 and 2.1 mM, respectively. Individually, they would not cause 
an acute response in ^ days; it is possible however that they individually might cause a 
chronic response, and even an acute response in 1-2 weeks. 

The total body burden curve, Cp°^^' , is also given in Figure 7.2(e). It indicates that the 
"toxic" body burden, Cp , 3.5 mM, is attained in 5 days. This indicates that an acute 
response may be attained within k days, dependent upon the acute toxicity tolerance 
distribution function. 



7.2.5 Overview of State-of-the-Art 

A variety of responses are attained in organisms dependent upon whether a mutagenic, a 
carcinogenic, a teratogenetic, a toxic or other response is being observed. Ail have 
different modes of action and induce different responses in cells or a whole body 

The main chemicals of concern in toxicity testing can be classified into the following: 

o metals (e.g., copper, aluminum); 

o organometallics (e.g., methyl mercury, organo tin, alkyl lead); and 

o organics (e.g., pesticide residues). 

A wide variety of organics cause a "physical toxicity" (e.g. gill effects). Other cause 
"narcosis" (e.g., a chemical effect). At a molecular level, it is not known how narcotic 
organics act, although several reasonable models exist. 

Regardless, the accumulating evidence indicates the following for narcotics (McCarty, 

1. Body residual concentrations are the key variable for predicting the chemical 
potency of chemicals in the biota. 

2. The body concentration at which a toxic effect is observed is essentially 
constant for similar organisms and narcotic mode of toxic action (3-6 mM 
acute toxicity). 

By extension, additional points result, including the following: 

1. The body burden at which toxic effects are observed for other classes of 
organic chemicals (e.g., phenols) with the same organism may be within the 
same order of magnitude, but at different levels. 

Complicating this relatively simple picture is the rather heterogeneous set of test results 
documented in the literature. This includes difficulties in explaining test results for the 

M39.3 7.8 

same chemical on a variety of different fish of different sizes. Some of these test 
results can be explained by the following points: 

1. Kinetics can explain many apparent differences. For example: 

o goldfish reach the critical body burden quickest of many fish species; 

o the time to equilibrium for large-sized fish of the same species is larger 

than for small-sized fish of the same species due to a number of factors 


i) the larger circulation time within the fish tissue, 

ii) the fish surface area/volume ratio 

iii) the gill surface area/volume ratio 

iv) the diffusional path lengths, and 

v) the effects of lipid tissue. 

2. The lipid content of fish can explain some differences particular kinetic 
differences. Recent evidence indicates that correlations exist between the 
elimination rate constant (which controls the time to achieve a critical body 
burden) and the octanol-water coefficient (K^^) for the fish species. The 
Kq^, which measures the tendency of the chemical to partition between 
octanol and water provides a good explanation for the ability of a chemical to 
partition between the fatty tissue of fish flesh and the water phase in which 
they swim. 

3. The ionization constant of the chemical in water affects uptake, because 
uptake through diffusion across the gill is affected by change. For example, 
ammonia ionizes according to the reaction 

NH^+ = NH3 + H^ 

Above pH 9.3, NH3 (ammonia) is the dominant form, while below pH 9.3, NH/^"^ 
(ammonium) is the dominant form. The most toxic form of total ammonia is 

'fl39.3 7.9 

7.2.6 Cumulative Effects of Different Chemicals Upon Toxicity 

The site of action within an organism is known with reasonable precision for only a few 
chemicals when a solution contains an individual chemical. The effects of multiple 
chemicals in solution is not well-known, although as indicated above, evidence is 
accumulating that a variety of chemicals can act in a cumulative and probably linear 
fashion when the same mode of action is involved. 

Organic chemical groups such as simple alcohols (methanol, ethanol, l-propanoi, 1- 
butanol, 1-hexanol, n-octanol, 1-nonanol, 1-decanol) and ketones (acetone, 2-butanone, 
etc.) cause narcotic effects upon fish such as fathead minnows, a typical species used in 
aquatic toxicity tests. 

The toxic effect of other organic chemicals such as phenols is complicated by ionization 
in the water and in the organism's body. Phenols have an "acute" body burden which is 
about an order of magnitude lower than that for narcotics such as alcohols and ketones. 
Metals, ammonia, and chlorine complicate the picture further because of the 
significantly different modes of action. 

The different sites involved include the following. Metals such as copper and zinc affect 
gas transfer and to a lesser extent, salt regulation of the gill. Ammonia affects the 
oxygen carrying capability of the blood and is directly toxic to liver cells. Aluminum 
may affect gill transport of gases and salts by chemically precipitating at the gill. 

The addition of the effects of these multiple chemicals can be synergistic or antagonistic 
or might be strictly addictive. For example, the Toxic Unit model (Chapter 3) indicates 
that higher hardness values decreases the effect of metal ion toxicity. Multiple sites of 
toxicity action from the different chemicals can, theoretically, cause a much greater 
effect then each chemical acting at a different specific site. The human example 
equivalent to the synergistic effect upon fish is someone who has a poor heart, who gets 
a bad cold or pneumonia and who hence is inuch more susceptible to a potentially "acute" 

139.3 7.10 

7.2.7 Theoretical Construct for Toxic Unit Model 

The theoretical basis for the toxicity unit model is reviewed in this section for two cases: 

o a single chemical; and 

o a mixture of narcotic chemicals. 

Its basis for a mixture of narcotic and non-narcotic chemicals is reviewed in 
Section 7.2.8. 

Single Chemical 

For a single chemical, analysis of the kinetic models indicate that the toxicity unit model 
is the appropriate model. This is based upon the following reasoning. For a single 
chemical with a fish concentration response Cp to ambient water concentration C^, and 
the corresponding fish concentration response curve which causes a toxic response (a 
"toxicity body residue") in 96 hours, Cp, the kinetic curves are respectively: 

Cp = C^ BCF (1-exp (-k2t)) 

Cj = Cj BCF (1-exp (-k2t)) 

where: t = time (days) 

k2 - elimination rate constant (days" ) 

C ' = water concentration which causes a toxic body burden in 96 hours 

C^ = ambient water concentration being tested. 

't 139.3 7.11 

The Toxic Unit model defines TU as: 


Hence, for a toxic unit of 1.0, 

That is, the toxic body residue concentration Cp will be reached in 96 hours, meaning 
that the ambient water concentration being tested is the threshold value for the acute 
response as measured previously. 

A Mixture of Narcotic Chemicals 

For multiple chemicals causing narcotic actions, the toxicity unit model may result in 
predicting the same toxic response as the kinetic models, but it does not give the same 
mathematical result in all cases. For the same modes of action, different chemicals 
result (see Figure 7.2(e)) in the following relationship for the "acute" body burden: 

^F,l + Cp^2 * ^F,3 + '^F,it = *^F,total 
where: Cp j = concentration in fish species from chemical 1. 

Cp 2 = concentration in fish species from chemical 2. 

Cp 3 = concentration in fish species from chemical 3. 

Cp ^ = concentration in fish species from chemical ^■. 

Cp ^otal " ^°^^' concentrations in fish species from chemicals 1 to ^t. 

In terms of the kinetics, the summation results in: 

C^_l BCFj (1-exp (-k2it)) 4 C^^j DCF2 (1-exp (-k22t)) + ... = Cp^^oxic 

'♦139.3 7.12 

where: C^ j = concentration of chemical 1 in water (molar); 

Cw -3 = concentration of chemical 2 in water (molar); 

BCFj = BCF for chemical 1 

BCF2 = BCF for chemical 2 

K2j = elimination rate constant for chemical 1 (d"M; 

K22 = elimination rate constant for chemical 2 (d" ); 

The kinetic model then indicates that the appropriate Toxic Unit model (TUM is: 


^F,! "■ ^F,2 + - 


The numerator has time varying exponentials for each chemical while the bottom is the 
cumulative sum of the numerator. 

If the narcotic chemicals all have the same elimination rate constant and the same value 
for BCF, the expression simplifies to a form similar to the linear addition hypothesis used 
for TU in Chapter 3. It is, 


'w,l ^w,2 


the total water concentration of these chemicals at which a toxic 

response is observed. 
Accordingly, the linear addition hypothesis for the toxicity unit model is a special case of 
the more general mathematical form. 

7.2.8 Practical Application of Toxic Unit Model 

Irrespective of the limitations of the TU model based upon kinetic considerations, it will 
continue to be a practical tool for assessing toxicity for the forseeable future. As noted 
above in Section 3.3 (EIFAC, 1987; deMarch, 1987a,b), the linear addition hypothesis 
(based upon a strict addition approach) has no satisfactory alternative because none of 
the theories of toxicity provide a precise or reliable estimate of toxicity for mixtures. 

«fl39.3 7.13 

The toxicity unit mode! has been checked previously in only a limited number of cases. 
Solutions tested have included gold mill effluents; data for applying it to rivers and 
stormwater have not been found. A few solutions have recently been tested by BEAK 
(internal data). 

The results of the test work on gold mill effluents (Flock, 1980) were as follows: 

Mine Predicted LC50 Observed LC50 

Schumacher Mine 0.8% LT 20% 

Dome Mine 0.9% tt% 

Kerr Addison Mine 2.2% 29% 

Campbell Red Lake Mine 0.2% LT 2% 

LT - Less than. 

The results indicated as percent are the degree of dilution of the water required to just 
obtain an acute response in 96 hours. The major components of toxicity were due to 
copper and free cyanide with minor contributions from un-ionized ammonia and zinc. 
Where individual chemicals had TU values of less than 0.1, the authors chose to disregard 
these chemicals in the calculations, assuming that such low values did not contribute 
significantly to toxic effects. 

These data indicate that the predicted LC50's are well below the observed toxicités, 
often by an order of magnitude. Hence, for these solutions, the calculations are 
conservative (i.e., overestimating toxicity), since solutions were less toxic than predicted 

The use of the model stipulated above in Section 3 continually needs to be emphasized: 

1. The results of the TU model should be treated qualitatively. 

2. Adjustments to the "linear addition hypothesis", where known, should be made. 

3. Chemical test work and toxicity test work upon synthetic solutions and actual 
solution mixtures will improve use of the TU model. 

'♦139,3 7.1* 

Another way to use the results of the test work is for calibrating the interpretation of 
the toxicity unit model. In this context, the phrase "calibrate the interpretation" means 

(a) obtaining data which indicates the uncertainty associated with numerical 
values for TU; and 

(b) defining whether an acute response will be observed at particular TU values 
such as 0.5, 1.0, 2.0, or 5.0, for a specific mixture of chemicals. The more 
complex the mixture, the more difficult it is to directly interpret the 
numerical values of the TU model due to synergistic and antagonistic effects 
in the mixture. 

7.3 Influence of Total Metal Concentrations Upon Toxicity Model 

Another major influence upon toxicity prediction is the type of metal data available. 
The toxicity model uses dissolved metal concentration as the measurement required, 
rather than total metal concentrations. 

This requires a correction factor to monitoring data, because much available monitoring 
data are based upon total concentrations, rather than dissolved concentrations. 

In fact, the dissolved metal concentration is not the proper surrogate for several metals 
because toxicity test work indicates that the ionic concentration is the cause of 
toxicity. One of the classical pieces of work in environmental science involves 
examining the effect of organic matter upon copper toxicity to algae. The qualitative 
observations indicated that two dissolved copper concentrations (for example 10"° M and 
10"^ M) had the same toxic effect to algae. However, when the concentration of cupric 
ion (Cu^'*') was calculated by correcting for complexation of copper with the different 
types and amounts of organic matter present, the concentration of Cu^"^ was the same in 
each solution (e.g., 10"" M). 

These influences can be properly accounted for, at least in a preliminary way, using the 
following concept. The mass balance for copper in solution where it has a sorbed phase 
and is complexed with two solution ions (hydroxyl ion, carbonate ion) results in a 
correction for copper. It must be calculated numerically from the following relationship: 

''139.3 7.15 

(Cu)y = b (Cu2+) + a (Cu2+) 1/2 

where: b = i + icof) IQ-^^'^a ^ (co|-)2 lO"'^-^^ + K^ (SS) 10"^ 

(C0|-) := (Alkalinity) {[Q-^^'^) lOP" 

a = 0.5 10-10-'^ 102PH 

Here: o Alkalinity is the total alkalinity assuming that the pH of the water is 

between 6.5 and 8.5; 

o pH is the pH of the water; 

o SS is suspended solids concentration (gm"-^); and 

o Kq is the linear sorption constant for copper (cc/g). 

The chemical data for dominant species and for complexation constants are derived from 
Baes and Mesmer (1986). 

Similar correction factors can be derived for other metals such as zinc, aluminum, etc. 
The key to using the data is having reasonable estimates of the linear sorption constant 
Kq. Compilations are available to provide order of magnitude estimates. The validity of 
the Kq approach for predicting particulate metal speciation requires further analysis 
because solid phases of metals will also form. The Kj-j approach is more applicable for 
concentrations in the ug/L range; its applicability in the mg/L to lO's of mg/L range 
particularly requires careful assessment. 

7 A Other Considerations 

This chapter has concentrated on narcotic-acting organics, summarizing the current 
understanding, and relating it to the constrict of the Toxic Unit Model. In considering 

''139.3 7.16 

other chemicals, two additional points should be borne in mind. Firstly, specific-acting 
chemicals will have a critical residue below that found for general narcotic organics. 
Secondly, it remains to be demonstrated how well the narcotic model predicts toxicity 
for asphyxiants, irritants, surfactants, etc. 

Suspended solids will also have some impact upon the fishery. It is plausible, but 
unproven, the extent to which sorbed metals can impact toxicity, whether directly or 
indirectly through desorption into solution and subsequent uptake. They also have a 
potential impact upon migrating fish, although sketchy literature evidence indicates that 
migrating fish have the ability to move through riverine waters containing 200-'fOO 
mg/L. The largest impact of suspended solids is upon siltation of spawning beds etc. 
Such a factor is accounted for in the HSI model. 

This work has also concentrated upon using rainbow trout as the test species. Different 
species have different responses. Most of the toxicity data are for trout and possibly 
fathead minnow, when other (possibly less sensitive) species are actually present. This is 
especially true for modifying factors such as oxygen and pH. Hence more robust species 
may be expected to survive conditions which stress trout. 

Finally, there is the question of future directions for implementing the model, for the use 
of, the models and futher development of the Toxic Unit Model. These questions of 
course depend upon the objective of using the Toxic Unit Model. Relevant objectives 

o Will it be used to ameliorate water quality in the Don River? 

o Will it be used to monitor actions taken by Wastewater Treatment Plant 

o Will it be used for control strategies? 

o Will it be used as an improvement in fisheries assessment tools? 

^^139.3 7.17 

Also, there are questions concerning its use, reflecting 

o whether it is useful now; 

o whether it needs further development before implementation; 

the credibility and feasibility of trying to model toxicity. 

In an absolute sense, one can say that if you cannot model it, you do not fully understand 
it. But, a model is still quite useful as an abstraction of reality as we understand it, 
since it assists in defining the critical areas of lack of knowledge. 

Perhaps the feasibility of predicting toxicity is the key area to be addressed. For a 
single toxicant, the answer to the question of feasibility is probably "Yes" in varying 
degrees. EPA-Duluth seems to have done it for acute Cu toxicity as a function of 
hardness, pH, temperature, DOC and suspended inorganics. For narcotic-acting organics, 
the workers such as McCarty, and collègues, and some of the Europeans indicates critical 
residue concentrations for acute lethality and to a lesser extent for sublethal effects. 

Predicting toxicity of complex mixtures however is a much more difficult task. This is 
acknowledged in this work where it is said that it will be most useful in a qualitative way 
- p3.9, that estimates cannot replace actual toxicity tests - p3.11, that it must be 
calibrated - p3.13, that there are few toxicity data to parameterize and/or validate the 
model - p3.i2, that managers must rely on past experience when interpreting predicted 
toxicity - p3.13. 

The key use of the toxic unit model in this work and in the analysis of the effects of 
spills, is thus directed to improving the tools available for examining the relative 
importance of canopy (temperature), bottom habitat; flow related variables and water 
quality. Its utility requires further testing; its application to water systems where 
toxicity is dominated by a few contaminants would appear to be first major step to 
further evaluating its credibility, its performance, its feasibility. 

'♦139.3 7.18 

7.5 Validation of Toxicity Model 

Future efforts will be directed to testing toxicity model proposed in this rep>ort and its 
incorporation into the Habitat Suitability Toxicity model. Results from four recent tests 
(BEAK, 1990) are now presented. 

7.5.1 Methods 

Samples were collected on May 't, 1990 from Undercliffe and Cecil CSO overflows, as 
well as from the Don River below the North Toronto WPCP and the creek passing through 
the Taylor Creek Park, The latter two samples were used as an indicator of 
characteristic river or creek conditions after a small storm. They were tested for acute 
toxicity using the 9é-hour static acute toxicity test, and their chemical composition was 
measured. The test was performed according to the procedures outlined in the Ministry 
of the Environment (1983), and Environment Canada (1980). Samples were aerated prior 
to commencing the test to increase oxygen levels in the two storm sewer samples. This 
resulted in no measureable TRC in any of the samples. 

The samples were characterized for both dissolved forms and total concentrations of the 
following substances (Zn, Cd, Mn, Co, Cu, Fe, Pb, Cr, Ni, Be, Ca, V, Al, Na, K, Sr, Na). 
As well, Chlorophenols, Specific Conductance, Ammonia-Nitrogen, pH, Total Dissolved 
Solids, Total Kjeldahl Nitrogen, Total Suspended Solids, and Dissolved Oxygen were 

The toxicity model described in Chapter 3 was then applied to the data to evaluate its 

7.5.2 Toxicity Results 

The two stormwater discharges were toxic to rainbow trout but the two surface water 
samples were not. The test data results are as follows. 












Don River 




Taylor Creek Park Creek 




Cecil Crescent 




Undercliffe Crescent 




* no toxicity observed over ^ day test period. 

The LC^Q (% by volume) is interpreted to mean that the sample would have to be diluted 
to 73% for the sample to just toxic (i.e., for 50% of the test rainbow trout to die after a 
'f day test period. 

There was no fish mortality or sublethal impairment observed in undiluted effluent in 
Treatment Plant and Taylor Creek Park samples during the exposure time. Most of the 
mortality in two other tested samples (Cecil Crescent and Undercliff Cresent) occurred 
gradually over the 96 hours of exposure. Temperature and dissolved oxygen levels 
remained stable throughout the exposure time at 15 •+ 1°C and above 8 mg/L. 

7.5,3 Toxicity Modelling 

The toxicity model described in Chapter 3 was applied to the measured chemical data 
and the toxicity of the samples forecast. The detailed results are given in Table 7.1 and 
are summarized here in the text. The following comparison of toxicity results with 
model calculations were obtained. 

'*139.3 7.20 

O i: 


«A «O lO 
O -H o 

• o o 

«O — < ON 

OO -H lA -H _ 

V ^^ 

ii -^ — 

O -i. o 

i-, S; H Q 

_ oj flj i^ ti 

U U N N 






Don River 



Taylor Creek Park Creek 



Cecil Crescent CSO 



Undercliffe Crescent 



Percentage of 
TU due to the following 
Chennical Components 
Ammonia Copper Zinc 




NDT * = no detected toxicity 

The unit TU, is defined as toxic units. A threshold of 1 indicates that the sample would 
be toxic (i.e., that 50% of the rainbow trout would die over the 4 day test period). It is 
equal to 100 divided by the LC^q (% by volume) given above. 

Of ail the possible components contributing to the toxicity described above, ammonia, 
copper and zinc are the principal ones which could potentially cause toxicity. Their 
contribution to the calculated TU values calculated by the model indicate that copper 
makes the largest contribution to toxicity with a minor possible contribution by zinc and 
ammonia. Due to their small contributions, it is concluded that the toxicity is mainly 
caused by dissolved copper. 

The models' calculated toxicity compares favourably to the observed toxicity. This 
provides some confidence in the use of the model as a screening tool for establishing 
toxicity. The model overestimates toxicity to some degree. This is within the 
uncertainties in the model. The model, does not consider possible complexation of 
copper with organic anions such as fulvic substances, which would tend to lower the 
predicted TU value, if considered. 



It is concluded that the model can be usefully used to forecast the potential toxicity for 
such samples when the chemical composition of key components are known. 

Based upon low oxygen values in the actual samples, the model of Chapter 3 was used to 
evaluate the effects of low dissolved oxygen. The dissolved oxygen effects, accordingly, 
result in the following increment in acute toxicity. 

Observed Increase in 

In situ DO Toxicity 

Cecil CSO 2.5 mg/L 20% 

Undercliff 3.0 mg/L 0% 




8.1 Genercd Considerations Re Don River Habitat 

Based on the many conflicting resource use demands being placed on the Don River 
watershed at the present time, the need for a comprehensive fish resource management 
plan or strategy becomes apparent if effective restoration and management of fish 
resources is to be achieved. Present urban and industrial development throughout the 
watershed and changing land uses in the upper watershed have already significantly 
altered the aquatic environment of the Don River. At the same time, increasing 
demands are being made throughout Ontario for increased recreational fishing 
opportunities. , 

In the case of anadromous salmonid fisheries using Lake Ontario and suitable tributary 
rivers, recreational fishing can create or stimulate significant economic activity in the 
region. A study by the City of Scarborough has estimated that over 1^3,000 anglers live 
in that city, and that close to $1,000,000 of economic benefit could be realized with a 
"properly managed and stocked Rouge River fishery". It has been estimated that this 
type of fishery management program on the Credit River is responsible for between 
$10,000,000 and $15,000,000 of annual economic benefit to iVlississauga. Similar benefits 
could be realizable in the Don River, if a quality fishery is restored. 

Unless there is a clearly stated management plan for this fish resource, restoration of 
aquatic habitats, water quality and fish fauna can only be measured or judged against a 
previous condition rather than against a future plan or strategy which is being 

To be effective, a fish management plan must relate to the habitat constraints and 
opportunities which exist in various sections of the river. Whether it involves habitat 
restoration or water quality improvement, the capabilities and potential of river habitats 
to produce the results being sought must be clearly and realistically assessed. 

^^139.3 8.1 

The need for this type of management plan becomes most apparent when one considers 
the evolution of the fishery in the Don River. Previously, the river supported a resident 
warm-weather fish fauna, and possibly a self-sustaining cold-water fish fauna. Each of 
these has significantly different habitat and water quality requirements. In the absence 
of an active management program, it can be expected that future environmental changes 
will continue to favour warm-water species over cold-water species, as has occurred in 
most of the watershed over the past half century. Since much of the lower river provides 
only poor habitat for warm-weather game species, such as the smallmouth or largemouth 
bass, these species will not support a significant sport fishery. 

The anadromous cold-water species are hatchery-supported, use Lake Ontario for feeding 
and growth, and move into tributary rivers in large numbers during the spawning 
periods. These species provide the potential for large and highly-sought recreational 
fisheries. This type of fishery presently exists on the lower Rouge River and Credit 
River even through stocking programs in these rivers have been limited. In order to 
facilitate a management strategy, aquatic habitats and water quality conditions would be 
managed and protected to meet the seasonal needs of these species. 

Finally, if the objective is to support natural reproduction of cold-water species in the 
lower river, a whole new set of environmental criteria relating to water quality, mid- 
summer flow levels, temperature and habitat conditions must be considered. 

The practicality of any of these options should be assessed based on habitat capability, 
following which a realistic resource management plan can be developed and an 
implementation program organized. Only when this has been done can environmental 
criteria or standards be set to ensure that habitat quality will be maintained or improved 
to meet the plan's objectives. This is clearly beyond the scope of the current study. 

To this date, the only habitat capability assessment carried out on the Don River system 
is that by MNR involving a general analysis, and two academic theses. 

At this stage, it is recommended that habitat conditions at least suitable for smallmouth 
bass be established as the minimum acceptable environmental criteria for the lower Don 

8.2 Use of the Index of Biotic Integrity OBI) to Measure and Monitor HSI 

Effectiveness and Significance 

The Index of Biotic Integrity (IBI) was developed to serve as an integrated measure of the 
health of stream ecosystems. The term "biological integrity" generally refers to an 
accepted standard set by ecosystems that have not changed structurally or functionally 
as a consequence of human activity, and can thus be used as a basis of comparison for 
ecosystems which have been altered to varying degrees. 

The IBI uses the fish community as a measurement parameter for biotic integrity. It 
consists of a number of ecological measurements or metrics in categories of species 
richness and composition, trophic composition, species abundance and physiological 
condition. Originally developed in the U.S. midwest, it has been adapted to suit southern 
Ontario streams and applied over a range of stream habitats by R.3. Steedman (1987) in a 
doctoral thesis. This included several sampling stations on the Don River distributed 
from the headwater tributaries to the lower main stem. 

The IBI results for the Don River system were as follows (from Steedman, 1987): 

River Section IBI Rating 

Upper Reaches (Headwater Tributaries) fair to good 

Middle Reaches poor to fair 

Lower Reaches poor 

These results, which provide a measure of the fish community and, thus, the biological 
environment, are in general agreement with HSI results if these were applied for the 
same target species throughout the watershed. For instance, the HSI for small mouth 
bass would be rated fair to good in the upper and middle reaches, and fair to poor for the 
lower reaches. 

The HSI provides a measure of the habitat suitability for a target fish species, while the 
IBI provides a measure of the ecological health of the fish community, including the 
target species, utilizing these habitats. The IBI is of limited value as a direct planning or 
management tool for watersheds since, unlike the HSI, it does not provide quantifiable 

«fl39.3 8.3 

habitat criteria which can be used as management objectives. It is these quantitative 
physical and chemical criteria which are required for planning and management of land 
use activities affecting the watershed, including stormwater management. However, the 
IBI is a useful tool for measuring and monitoring the success of achieving the HSI 
objectives as this is ultimately reflected in the fish community. If the HSI parameter 
values are appropriately set and if the HSI objectives are achieved, the target fish 
species should prosper along with associated fish species in that aquatic ecommunity. 
Thus, the IBI score should be high to reflect this. Conversely, if the target fish species 
does not survive and the IBI score is low, the habitat suitability criteria are either set at 
inappropriate levels or are not being achieved. The IBI is a very useful monitoring tool in 
this regard, since it is a healthy fish community which is the ultimate objective. Habitat 
(HSI) management is the means for achieving this objective. 

8.3 Recommendations 

8.3.1 Specific Recommendations 

The following specific recommendations result from this study. 

1. To effectively manage aquatic resources of the Don River and achieve fisheries 
management objectives, a comprehensive and integrated land use management plan 
for the total watershed is required. 

2. The land use plan must examine the limits of watershed urbanization beyond which it 
loses its capacity to function as a stream ecosystem and becomes little more than a 
network of urban drainage channels. 

3. The HSI approach to determining acceptable habitat criteria for a target fish species 
should be applied on individual tributaries or specific river reaches which could be 
affected by a proposed development. In this report, HSI's for the target species have 
been applied to the average conditions found in large subsections of the watershed. 

li. Fisheries objectives specific to the Don River and its various tributaries should be 
established. The District Fisheries Management Plan is generic for the Don River 
since it considers the region as a whole, rather than being shaped specifically to the 

Don River. 

'f I 39.3 ZA 

5. Key habitat parameters and the resident fish community (IBl) should be monitored on 
a regular basis to ensure that the fisheries objectives are being achieved. This will 
also provide useful data to refine and better adapt the HSI model to a Don River 

6. Toxicity testing and chemical characterization of different waters from the Don 
River (various tributaries; various main stem sections; various sources including 
CSOs, storm sewer discharges, treatment plant effluents) should be carried out to 
check the predictions of the toxicity unit model and the calibration used to include 
it in the HSI model. 

7. Protocols for combining: (1) bioconcentration measurements; (2) bioassays (acute 
toxicity tests); and (3) residual effects on fish need to be formulated to obtain data 
for all three phenomena (BCF, acute tests, residues) since the kinetic models 
indicate that they are all interrelated. 

8.3.2 General Recommendation for Further Work in Fisheries - Water Quality Area 

A need for flood plain mapping, land use assessment and classification of stream bank 
and riparian vegetation condition was identified, in order to permit establishment of 
baseline conditions, and required buffer strips within the Plan. This recommendation 
arose from the meeting on setting fisheries objectives attended by various people from 
MOE, MNR, MTRCA, BEAK and Theil. It is made because the streams need to be 
classified as to their degree of cover and its influence on stream temperature and 
whether there is a likelihood of developing a fishery. 

An other major requirement is to amplify the modelling approaches used in this study, to 
establish the magnitude of fisheries benefits associated with water quality control. 

These general recomendations are based upon the following points. 

1. A Fish Management Plan has not been established specifically for the Don River 

^139.3 8.5 

2. Little time has been spent in general by MNR upon degraded streams in relation to 
non-degraded streams (Martin-Downs, personal communication). 

3. Rehabilitation work by MNR has concentrated upon cold water streams where the 
largest return upon money spent, is achieved. 

if. Limited data have been gathered upon the Don River. 

5. The Don River has only recently been screened in terms of planning controls in the 
later 1980's. 

iA Recommended Approach 

Based on the foregoing, the following approaches are recommended: 

1. classification of aquatic habitats in various sections of the Don River for fish 
communities and species, including a ranking of habitat suitability for each; 

2. development of a fish resource management plan which optimizes habitat 
opportunities in each section of river for primary species of importance or interest; 

3. examination and amplification of representative, key species (guilds) for HSI model 
application; and 

It. development of habitat variable criteria which will maintain habitat suitability at 
the desired, specified level for the representative species. 

It is strongly recommended that the fish species assemblage/habitat requirement 
classifications be completed for the Don River as a logical information prerequisite to 
the development of a fish resource management plan for the watershed and a basis for 
establishment of habitat protection guidelines or criteria related to watershed 
development. The theses written by R. Steedrnan and R.J. Morris provide some further 
information or analyses in this regard. 

'*139.3 8.6 

These habitat criteria can be tested and tnodelled to ensure that changing land uses do 
not further reduce habitat suitability and to ensure that source water quality control 
attains the improvement needed to allow for restoration of the fishery in the Don. 

The effectiveness of remedial or mitigative measures to protect habitat quality was 
tentatively modelled in this work. It requires further testing. It could then be used as 
part of the planning and approvals process. 

The Don River appears to be an excellent candidate for this type of proactive and 
innovative watershed management approach. The river retains excellent habitat 
conditions in a few headwater reaches. There is a good habitat inventory and assessment 
database for use in suitability classification. The river currently has the potential for 
supporting an important recreational fishery and even perhaps an anadromous fishery. 
The watershed is experiencing a rapid rate of urbanization in the headwaters, and other 
land use changes in existing developed areas (e.g., the St. Lawrence Square Area). 
Results of this program on the Don River should have direct application to other 
tributaries of Lake Ontario experiencing urban land use changes in their watersheds. 

139.3 8.7 


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'H39.3 9.1 

deMarch, B.G.E, 1987a. Mixture toxicity indices in acute lethal toxicity tests. Arch. 
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deMarch, B.G.E. 1987b. Simple similar action and independent joint action - two similar 
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equilibrium calculations: effect of pH and temperature. 3. Fish. Res. Board Coin. 
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thiocyanate to trout. Transactions of the American Fisheries Society 1 1'f. 

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Indian and Northern Affairs Canada. 198'f. The acute toxicity of thiocyanate and 
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mill effluents. Mining, Mineral and Metallurgical Processes Division, Industrial 
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Kovacs, T.G. and G. Leduc. 1982. Acute toxicity of cyanide to rainbow trout ( Salmo 
gairdneri) acclimated at different temperatures. Can. 3. Aquat. Sci. 39: l'f26-l'*29. 

Larson, G.L., CE. Warren, F.E. Hutchins, L.P. Lamperti, D.A. Schlesinger and W.K. 
Seim. 1978. Toxicity of Residual Chlorine Compounds to Aquatic Organisms. U.S. 
Environmental Protection Agency, Duluth, Minnesota. EPA-600/3-89-023. 

Martin-Downs, D. 1988. Don River Biological Inventory Past, Present and Future 
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'^139. 3 9.2 

Mason et al. 1979. Compilation of Database for Several Fish Species. U.S. F.W.S. 

McCarty, L.S. 1986. The Relationship Between Aquatic Toxicity QSARS and 
Bioconcentration for Some Organic Chemicals. Environmental Toxicology and 
Chemistry. 5: 1071-1080. 

McCarty, L.S. 1987a. Relationship Between Toxicity and Bioconcentration for Some 
Organic Chemicals: I. Examination of the Relationship. Iru QSAR in 
Environmental Toxicology (K.L.E. Kaiser, Ed.). pp. 207-220. 

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'fl39.3 9.3 

Steedman, R.3. 1987. Comparative Analysis of Stream Degradation and Rehabilitation 
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i4\39.3 9.i» 


Use of Ecosystem Approach to 
Development of Levels of Protection Criteria 


This appendix provides background documentation for developing the Levels of 
Protection Approach for the following water quality benefits: 

o Contact and Non-Contact Recreation; 
o Fisheries Enduse; and 
o Aesthetics. 

This appendix was developed by study personnel after a series of meetings of MTRCA, 
MOE, MNR and study team representatives. The meetings involved evaluating factors 
limiting the Don River fishery and other goals required to attain a quality of water which 
may be desired by the General Public. 

The meetings lead to the development of parts of this supporting document (particularly 
Chapters 2 and 4) and assisted in developing the Levels of Protection Table given in 
Chapter 1 and the main summary document. This appendix was also materially assisted 
by the participation of various agency and study personnel in the Rouge River Water 
Management Study, and draws in part from the results of that study. 

The material detailed in this appendix is intended solely to provide an overview of all 
factors necessary to obtain an understanding of the complexities of watershed planning 
from an Ecosystem approach. Substantially more refinement of this material is required 
before it can be effectively used. 

As such, the information presented in this appendix do not represent the policy or 
position of the MTRCA, MOE or the MNR. 





The majority of the Don River is an urban water course subject to degradation from a 
mixture of point and non-point source discharges. The upper reaches are a non-sewered, 
rural water course which formerly was dominated by agricultural sources but which is 
rapidly undergoing urbanization and the impacts of construction. 

In the near future, the watershed will essentially be completely urbanized. The water 
quality will further deteriorate unless new development is sufficiently controlled. 

Redevelopment within present urban areas and further densification may also promote 
deterioration unless controls are implemented on such development. Controls on existing 
sources to achieve improvements in water quality may require extensive retrofitting. 

This, at first glance, appears to be a bleak picture. In fact, substantial opportunities for 
improvement in water quality control will occur over the next 50 years as redevelopment 
occurs and urban infrastructure improvements are made. These opportunities must be 
captured in order to make a water quality management plan successful. 

Present Water Quality 

Monitoring data are available from six stations in the Provincial Monitoring Network and 
from specialized water quality monitoring programs established for TAWMS (e.g., for 
pesticides, dry weather flow estimates, etc.), and the Enhanced Monitoring Program. Its 
analysis indicate that the upper undeveloped reaches are impacted mainly by agricultural 
activities and construction associated with development of the urbanizing fringe. The 
middle reaches are further impacted while the downstream main stream below the 
confluence of the East and West Don has the worst water quality. Special tributary 
streams (Wilkett Creek, Massey Creek) suffer from CSC and/or industrial 
discharges/spills effects. 

'H39.3 Al.l 

The water quality data for the 1980's indicate that the river is often turbid, and 
eutrophic. It has high bacterial counts and high temperatures in the summer. The river 
has plentiful oxygen resources with few observations below 6 mg/L. This indicates that 
treatment and control of oxygen demanding substances has achieved the objectives of 
water quality control programs implemented previously in the form of wastewater 
treatment plants and construction of separate sewer systems. The river is likely toxic in 
the lower reaches downstream of the North Toronto WWTP to Lakeshore Blvd. due to 
ammonia discharges. Toxicity due to metals or synthetic organic chemicals (SOC's) are 
plausible but uncertain due to sorption onto suspended solids and a paucity of data. 
Inplace pollutants may be problematic in the Keating Channel where they may pose an 
effect on salmonoid fish migration. The fishery quality is poor, but this may be primarily 
due to habitat/hydrologic factors. 

The long term trend analysis of water quality in different reaches shows a gradual 
improvement for certain parameters (e.g., BOD, ammonia) and occasional "step" type 
improvements for particular parameters (e.g., BOD). These "steps" are generally 
associated with removal of certain STP discharges from the system (e.g., Richmond Hill 
in 1979). The gradual improvements appear to be associated with refinements in 
treatment. Trends are apparent over a twenty year period for two organic compounds 
(PCB's, reactive phenolics) but no trends are apparent for trace metals or other organic 
compounds because the monitoring data strings are too short. 

Seasonal effects are also evident in the data set. They are caused by temperature 
variations (e.g., dissolved oxygen saturation) and flow effects and the effects of flow 
upon suspended solids. The suspended solids effects are observed for metals and trace 
organics which sorb to, or are associated with the solid phase. In many instances, the 
highest exceedances of PWQO's are observed during periods of high suspended solids 
concentration. Whether such concentrations represent toxic conditions need to be 
evaluated because many toxicity tests are conducted in the presence of only small 
quantities of particulate matter. 

^^139.3 A1.2 

Objectives of this Appendix 

The objectives of this appendix are: 

(i) to provide a framework for managing water resources in the Don River which 

cover societal objectives related to a balanced ecosystem, public health, public 
safety, fisheries and terrestrial attributes; 

(ii) to enunciate the meaning of ecosystem orientated principles; 

(ill) to develop long-term (approximately 50 year) goals for this framework based 

upon ecosystem orientated principles; 

(iv) to develop short-term and long-term objectives to fulfil these goals; and 

(v) to provide the background to the development of the levels of protection 

approach to measuring improvements in Don River Water Quality. 

Other activities are necessary for implementing measures to improve water quality. 
These include: 

(i) review the goals and objectives suggested herein and modify as required; 

(11) enunciate criteria and policies for a 5-10 year-frames which can lead to 

attaining these goals; 

(iii) suggest a plan for implementing these policies; 

(iv) suggest procedures for auditing the implementation of a plan; and 

(v) suggest agencies/municipalities which should be responsible for implementing a 


These activities would need to be carried out in the future with a set of procedures yet 
to be defined by the appropriate agencies. 

'fng.S A1.3 


The water of the Don River is degraded due to urban and industrial impacts. Linkages 
with other watersheds through atmosphere cycles and impacts from agriculture are of 
secondary importance. A return to the pristine condition of pre-European settlement is 
not realistic in our lifetime, or perhaps ever. However as human society attempts to 
come to grips with the carrying capacity of the planet, any tendancy towards restoring a 
small riverine ecosystem to a more balanced condition will result in a small contribution 
to a larger scale ecosystem. Only by the step-by-step approach of restoring various 
small ecosystems does the sum of many small effects result in a large effect for the 
overall ecosystem. 

Perspective on Environmental Degradation on Don River 

Degradation of Water Quality has occurred in the Great Lakes basin since European 
settlement. In order of effects, the following events have had the greatest impact upon 
the Great Lakes and associated riverine systems. 

(i) glaciation; 

(li) post glaciation including revegetation and isotatic rebound; 

(iii) deforestation by European settlement and development of agriculture; 

(iv) sanitary sewage and partial treatment; 

(v) urban stormwater runoff through sewers; Late Twentieth Century agricultural 


(vi) atmospheric transport of contaminants; 

(vii) rural or estate developments with ditches and septic tanks; and 

(viii) groundwater seepage. 

Humans are a part of the ecosystein. Each influences the other. Many of the present 
and future urban, industrial, and commercial uses of these ecosystems have a degrading 
effect on them. As long as the Don River watershed remains urbanized, many of the past 
ecological changes are irreversible. Only with the next glaciation age and the subsequent 
post glaciation period is it probable that an ecosystem similar to pre 1800 may develop. 

^139.3 Al.«* 

Ecosystems and nature have many unpleasant, even dangerous characteristics which 
impact humans. Atmospheric conditions include violent storms and excessive heat or 
cold. Aquatic conditions impacting human health include poisonous plants, standing 
water that breed mosquitos, streams from which swarms of black files originate, waters 
that contain piranha, and leaches, and contacted diseases such as swimmer's itch. 
Aquatic conditions which impact aesthetics, include fish mortality resulting from natural 
causes, decaying algal mats on shorelines, and marsh gases (methane, sulphide) from 
decaying vegetation. 

Degradation of water and ecosystems is unacceptable to many people. But complete 
restoration is impossible due to the probability that settlement induced ecological 
changes are irreversible. Some changes occur due to nature. For example the sand spit 
which protected Toronto Harbour prior to European settlement was severely breached by 
storms in IS^Z-^'f and 1858 (Whillans, 1977). But many changes occur due to man. For 
example, the shift in direction of the Don River outlet, degradation of the wetlands and 
the virtual elimination of the delta and associated marshes has resulted from 
development in the watershed after European settlement and in the Harbour. 

Rehabilitation, enhancement, wise use (conservation) and mitigation (see Figure 2.1) are 
midway courses between degradation and restoration which can be used to stop and 
reverse the long-term trend of continual ecological degradation. But their 
implementation through management policies, engineered source controls, and mitigating 
measures can only be conducted in a pragmatic way since we have no tested theory of 
ecological rehabilitation (Francis et al., 1979). Neither is a tested theory nor much 
evidence available for the economic and institutional aspects of rehabilitation and 

Ecosystem Approach to Planning 

An ecosystem is composed of various biological niches within the watershed and the 
interacting elements of water, air, land and living organisms, including man. An 
"Ecosystem Approach" is based upon using these various biological/physical niches as the 
fundamental building blocks for the plan. It necessitates explicit recognition of the 
exchange of materials between these building blocks. The exchange of material which 
has conventionally been recognized in Water Resources Planning is the transport of water 

'H39.3 A1.5 

through the atmosphere, and subsequent rainfall. The material exchange explicitly 
recognized in water quality management is the discharge of fecal material, nutrients, 
suspended solids, trace metals and toxic organics to the receiving water after partial or 
incomplete treatment. Implicitly recognized is food production, mining, paper 
production etc. in other watersheds and the transport of these "raw materials" into an 
urban basin to form building blocks for the wastes subsequently discharged. 

An ecosystem approach to planning "necessitates explicit recognition of the transport of 
materials such as atmospheric pollutants into and out of the Basin, in biosphereic 
perspective. The ecosystem approach provides the philosophic basis for a view of man as 
part of nature. It directs the efforts of 'different human institutions, industries and 
government agencies' toward treatment of the patient (the Ecosystem) rather than the 
symptoms of the disease. It relates the biological and technological activities of man to 
the carrying capacity of the Ecosystem" (GLRAB, 1977). 

Past Applications of the Ecosystem Approach to Planning 

The Governments of Canada and the U.S.A. adopted the "Ecosystem Approach", under 
the 1978 Great Lakes Water Quality Agreement, as the basis for future Water Quality 
Management within the Great Lakes. Attempts have been made and are still being made 
to incorporate this approach into the advisory and management structure of the 
International Joint Commission on Canada-America Boundary Waters (IJC). 

Management of various components of the environment were attempted in the 1970's 
(GLRAB, 1978) including: 

(i) new environmental legislation; 

(li) dialogue on the mutual benefit to water quality and fisheries programs of 

coordinated efforts on Great Lakes surveillance; 
(iii) research relating environmental quality to human health; and 

(iv) assessment of the implications of land use activities in relation to other parts 

of the Great Lakes Basin Ecosystem. 

"These steps, however, remain separate in that they lack the integrative framework 
linking these and other human activities with those of non-human parts of the Ecosystem 

«,139.3 A1.6 

and biosphere. This necessary integrative framework is an ecosystem approach. " 
(GLRAB, 1977). 

The ecosystem approach was also mandated in the Great Lakes Charter signed by the 
Premier of Ontario and the American Governors of Great Lakes States in 1985. The 
charter notes the following: 

"The planning and management of the water resources of the Great Lakes Basin should 
recognize and be founded upon the integrity of the natural resources and ecosystem of 
the Great Lakes basin. The water resources of the basin transcend political boundaries 
within the basin, and should be recognized and treated as a single hydrologie system. In 
managing the Great Lakes basin waters, the natural resources and ecosystem of the basin 
should be considered as a unified whole." 

Definition of Ecosystem Approach to Planning 

An ecosystem approach to water resources planning is difficult to define adequately. 
The above statements do not present a definition of the "Ecosystem Approach to 
Planning". Rather, they describe the elements of an ecosystem approach; the social, 
philosophical and ecological basis for the approach; and its advantages. 

An ecosystem approach may be defined as the following: 

(i) the plan uses the various biological niches of the watershed as the basic 

building blocks of the plan; 
(ii) the plan uses natural rates of cycling of material between water, air and land 

as one basis for defining unpolluted conditions; 
(iii) the plan views various living organisms including man as the basic biological 

building blocks of the plan; 
(iv) the plan defines pollution as an unbalanced ecosystem resulting from 

accelerated rates of cycling of matter or from the entry of toxic substances 

into these cycles which cannot be tolerated by particular plants or living 

organisms including man; and 
(v) the ecosystem provides the integrative framework for relating various human 

activities to the non-human parts of the ecosystem. 

'fl39.3 A1.7 

Application of Ecosystem Approach to Don River Water Management 

The application of an Ecosystem Approach to the management of water quality in the 
Don River requires that a holistic Ecosystem based plan first be adopted. An ecosystem 
based plan would take the perspective of perhaps a 50 year planning horizon. Then from 
this plan, a short term plan (with perhaps a 5-10 year planning horizon) and a long-term 
plan (with a 20 year planning; and/or a 50 year planning horizon) would be developed for 
Water Quality Management. 

An Ecosystem Approach to planning is difficult to do within the original mandate of the 
Terms of Reference of this Water Quality Management Study. With the inclusion of this 
fishery related component, it becomes somewhat more feasible. However, the basis for 
the formulation within this study is incomplete. A complete plan is based upon fisheries, 
water quality, terrestrial habitat, human values (such as human health, human safety 
economic development and recreation), and erosion and flood control and sets priorities 
where there are conflicts. 

In this study, a first cut is made at presenting an ecosystem approach to developing 
water management goals. A comprehensive framework is developed in which ecosystem 
values are placed within the human context. If such ecosystem values cannot be placed 
in human terms, they are left out for the present. Human terms are used as the basis for 
expressing ecosystem values because this forms a framework to which various political, 
social and economic human systems can relate. Aspects of the ecosystem most directly 
related to water quality are fleshed out in the plan. Other aspects (terrestrial habitats, 
an indepth fisheries habitat plan, flood control, etc.) will need to be fleshed out in other 

A statement of water quality goals and objectives for the short term in the Don River 
has been the subject of some debate over the past decade. In the synopsis of opinions of 
the various institution stakeholders (Gumming Cockburn, 1987), goals ranged from status 
quo to attaining Provincial Water Quality Objectives and instream wading. It was 
generally agreed that "pristine" water quality objectives were not realistic, since the Don 
River is an urban water course. It was also generally agreed that some improvement in 
environmental quality is desirable. Accordingly, objectives were stated as a general 
narrative. They (Gumming Gockburn, 1987) advocated that the objectives be further 
defined as the development of the management plan proceeds. 

'»139.3 A1.8 

This study has attempted to establish long term goals and short-term objectives which 
have the following characteristics: 

(i) they are ecosystem-based; 

(ii) they are ambitious in the long term, but realistic in the short term; 

(iii) they find the status quo to be unacceptable and hence require improvement in 

order to just maintain the status quo; 
(iv) they require the setting of bench mark criteria for auditing; 

(v) they recognize that the predictive science for assessing the response to various 

remedial measures and restorative works is presently imprecise but will 

improve in the future; 
(vi) they recognize that improved management; retrofitting and rehabilitation; and 

redevelopment are 3 tools available for obtaining improved environmental 

quality; and 
(vii) they allow for redefinition of the objectives in the future as public demands 

for environmental quality change. 

The approach detailed in the remainder of this appendix is to formulate goals which are 
long-term in perspective and which are ecosystem based. For these goals, short-term 
and long-term objectives are then established. The water quality objectives are 
established mainly for the short-term (implementation period of 5-iO years). Long term 
objectives (e.g., 50 years) are considered but their attainment is less precise because 
they are much more dependent upon opportunities such as redevelopment. The timing of 
redevelopment is known much less precisely. 

The next step in development and implementation of a strategy for water quality 
improvement is to examine management options, remedial and mitigating measures and 
control options in addition to human factors for achieving short-term objectives. Their 
potential effectiveness, costs, ecological implications and other factors are then 
examined and an implementation strategy developed. This step is summarized in the 
Summary Report. Other steps will need to be carried out in the future. A detailed 
implementation plan will be required. Milestones for plan implementation and criteria 
for auditing plan implementation and the success of the plan are then established. The 
plan is then audited during implementation, because it is doubtful that implementation 
will be complete before the original short-term objectives are changed. 

U39.3 A1.9 

This however allows for the dynamic process which will occur in water quality 
management given in Figure XX (diagram of this process). It however is based upon long- 
term goals can are ecosystem-based and which will be a benchmark against which all 
future short-term objectives, implementation measures, redevelopment proposals and 
economic forces can be assessed. 

Scope of the Remainder of this Appendix 

The long term goals and associated short-term and long-term objectives are described. 

«,139.3 ALIO 


A 1.3.1 Statement of Goals 

General; Quality of Life Within Great Lakes Ecosystem 

1. Linkage to Great Lakes Ecosystem: Recognize that the Don River watershed is a 
component of the larger Great Lakes ecosystem and that appropriate watershed 
management efforts will benefit the Great Lakes, particularly Toronto Harbour and 
the nearshore area of Lake Ontario adjacent to Toronto Harbour. 

2. Pride In Restored Don River Ecosystem: Take pride in a restored Don River 
Ecosystem - its system of interconnected waterways and valleys; its head waters, its 
source and its estuary; a balanced ecosystem unit within the most heavily populated 
metropolitan area in Canada. 

3. Balance of Economic and Environmental Values: Balance the mutual benefits of 
sustained economic growth, development and redevelopment; and ecological health 
and environmental quality within the Don River watershed. 

It. Quality of Life and Land Ownership: Take pride in the quality of life opportunities 
provided through public and private ownership and collective management of the 
valley system. 

Public Health and Aesthetics 

5. Swimming: Swim in the Don River without becoming infected by disease or soiled by 
waste films on the water surface. 

6. Drinking Water: Drink through incidental ingestion, surface and groundwater 
supplies within the watershed that are free of harmful viruses, protozoa and poison. 

7. Fish Consumption: Eat fish from resident Don River populations knowing they are 
uncontaminated by dangerous chemicals. 

'H39.3 ALU 

8. Aesthetics: Delight in the enjoyment of clear stream waters (in the seasons when 
waters should normally be clear) that have no unpleasant odours, abnormal algal 
growths or unsightly industrial and domestic waste. 

Public Safety 

9. Erosion and Flood Control: Maintain dwellings adjacent to the river valleys secure 
in the knowledge that they will not suffer damages from erosion and flooding. 

10. Risk to Life in Valley Lands: Enjoy open space opportunities in the valley streams of 
the Don River secure in the knowledge that users are not exposed to undue risks to 

Fisheries and Riparian Habitats 

11. River Beds as Fish Habitat: Enjoy the beauty of natural aquatic habitats and river 
beds that are uncontaminated by abnormal algal growth and unsoiled by industrial 
and domestic wastes. 

12. Angling: Angle in the Don River with some expectation of encountering various 
preferred species of fish. 

13. Enjoyment of Plants and Wildlife: Enjoy with pleasure a healthy riverine/valley 
environment, watching birds, plants, mammals and fish in their natural environment 
doing what they have always done. 

I'l. Wildlife and Waterfowl: Delight in the enjoyment of terrestrial habitats that 

support populations of wildlife and waterfowl. 

A 1.3.2 General Rationale for Long-Term Goals 

The long term goals are expressed in a manner consistent with introducing statements to 
the Great Lakes Water Quality Agreement of 1976. They are consistent with 

terminology in the 1976 agreement of: 

«fl39.3 A1.12 

o "restore and maintain the chemical, physical and biological integrity of the 
waters of the Great Lakes Basin ecosystem; 

o "the waters of the Great Lakes Basin system should be free from deterious 
materials resulting from human activity; and 

o "the virtual elimination and zero discharge of persistent toxic substances". 

and in the recent 1986 Great Lakes Water Quality Agreement of: 

o "to restore and protect the chemical, physical and biological integrity of the 
Great Lakes Basin Ecosystem as a multi-use resource whose base provides the 
settling and foundation for social development and economic investment. 

The direct linkage of the Don River to the nearshore ecosystem of Lake Ontario and 
perception of the public for riverine water quality require goals consistent with these 

The language of the Goals has been based upon the images of a restored environmental 
quality for the Great Lakes developed by George et al. (1979). The language was adapted 
into human terms (as noted above) for the Don River. The imagery of the goals are 
similar to those being considered by MTRCA for the Rouge River Watershed Management 

The goals are not as idealistic as some publics may desire due to the extremely complex 
nature of urban linkages and associated environment quality. The language is consistent 
with the statement of the DC that "the complete restoration of the chemical, physical 
and biological integrity of the water of the Great Lakes Basin Ecosystem will not occur 
in our life times". But such ideals "are a necessary part of such a serious, complex, and 
fundamental enterprise as the 1978 Agreement". 

^139.3 A1.13 

A 1.3.3 Description of Individual Goals 

The background of the individual goal statements are now discussed. 

1. Linkage to Great Lakes Ecosystem 

The goal re-emphasizes that the Don River is one part of the Great Lakes Ecosystem and 
the linkage of the River to the Lake through the effects of Don River loadings on water 
quality and ecological balance of the nearshore of Lake Ontario. 

2. Pride in Restored Don River Ecosystem 

This goal expresses the general feeling of people that "restored" or "good" is a significant 
benefit even though they may not actively participate in using the resource. This feeling 
is often based upon general knowledge and perceptions rather than direct knowledge or 
contact with the resource. This goal is the goal which various economists attempt to 
quantify under the category "indirect benefits", "intrinsic values", or "non-use values". 

This goal statement recognizes that a balanced riverine ecosystem, in which all 
biological, hydrological and chemical processes interact in a balanced fashion with human 
society, is a key indicator of the health of the river and of a "restored" Don River. The 
difficult part of examining this goal is to define quantitatively what constitutes a 
"balanced ecosystem" and the associated interactions and linkages. This definition will 
require considerable work in the future. In this study, the presence of key biological 
niches which are integrators of a balanced food web, is chosen as the appropriate 
approach at this time. 

3. Balance of Economic and Environmental Values 

This goal recognizes that our political system oscillates between economic growth and 
restoration of ecological health and environmental quality. It suggests that a balance 
between "economy" and "environment" is most desirable. It acknowledges that much 
more work is needed to define sustainable development within the context of the 
carrying capacity of the ecosystem of the Don River, the Great Lakes, and the planet. 
An indication of similar goals in other political jurisdictions is the possible new federal 


agency, the "Centre for Sustainable Economic Development" to be based in Winnipeg. As 
noted in recent (January 1989) press articles, the objective of the centre is to promote 
advice and technology to businesses and governments for economic growth with minimal 
ecological damage. 

In examining the concept of carrying capacity, a differentiation needs to be made 
between various types of substances in the water. Some substances such as particulate 
and dissolved organic carbon, phenols, etc. degrade through microbiological processes 
while others do not degrade. Of those which do not degrade, some such as chloride are 
relatively innocuous while others such as PCB's are carcinogenic to humans (and possibly 
to biota) at elevated concentrations. Degradation of such "toxic substances" does not 
occur because microorganisms have not yet evolved appropriate enzyme systems. This 
results in a split of substances with respect to using the concept of carrying capacity in 
environmental management. For substances such as BOD and TP, the ecosystem has an 
assimilative capacity for such substances at a low flux to permit a balanced ecosystem. 
For substances such as "non-degradable" toxics, their eliminations from discharges is 
mandated because the human health impacts are highly uncertain. 

f . Quality of Life and Land Ownership 

This goal recognizes that public ownership has, historically, been a prime vehicle for 
ensuring environmental management of critical land areas, especially as related to 
maintaining riparian vegetation etc. It recognizes that valley lands are a crucial portion 
of the watershed for attaining goals related to fisheries, terrestrial, riparian and 
instream habitat and a necessary component for water quality management. But 
substantial portions of the Don River Valley lands are a private ownership. It may not be 
possible, practical, economic nor desirable to bring all privately-owned lands into public 
ownership. Collective management provides a tool for attaining quality of life and 
environmental objectives for both privately owned lands and publicly owned lands. 

European approaches in which constraints on how privately-owned historical buildings can 
be modified and used, may provide a useful model, for involving private land owners in 
"collective management". 

'fl39.3 A1.15 

5. Swimming 

This goal assumes that contact recreation (swimming) may be feasible over the long- 
term. However, in the short-term, non-contact recreation is the only feasible goal 
without complete control of all STP, CSO and stormwater discharges. Occasional, 
incidental contact with the river water presently occurs by people who are wading etc. 
A minimal goal for the short-term is that they be free from diseases caused by 
pathogenic bacteria of human origin after incidental contact with Don River water. 

The swimming goal is viewed as independent of other environmental health goals since 
fecal organisms represent a small portion of the total bacterial to biomass in an 
unbalanced ecosystem. 

There are several points about assessing the suitability of water for swimmers and the 
impact of control which will affect these objectives over the short-term and long-term. 
The water quality parameter used to assess possibilities of swimming (fecal coliforms) 
may change in the future. This may fundamentally change present assessments of 
swimmability of the water. The degree of control necessary to achieve the long-term 
goal is assessed elsewhere in this plan. The predictive tools used for establishing the 
effectiveness of control require refinement. 

6. Drinking Water 

This goal assumes it is not probable that Don River surface water will be of a potable 
water quality for direct ingestion within the forseeable future due to the impact of 
stormwater systems. The protection of drinking water from pathogenic bacteria can only 
be assured after disinfection or boiling of the water. Typical disinfection techniques are 
those employed in water treatment plants. Similarly, an assurance that groundwater 
supplies from an urban area meet potable water standards for various water quality 
parameters (fecal bacteria; nitrates) cannot be made without more research on loadings 
to groundwater, groundwater dynamics, and evaluation of appropriate remedial measures. 

The resultant goal, thus, is quite realistic. It recognizes that incidental ingestion of 
watershed water will occur. 

tt[39.3 Al.lé 

Its implications include the following. Short-term water quality must be appropriate to 
prevent harmful effects to humans, or management sytems must be in place within the 
health care system to remediate health impacts of incidental ingestion during wading and 
other incidental body contact with Don River water. Public liability for such ingestion 
needs also to be examined. 

7. Fish Consumption 

This goal uses resident fish populations (complete life cycle) as an integrator of chemical 
contaminant burden (heavy metals; and industrial, agricultural, and horticultural organic 
chemicals) to various ecological niches and to humans. It expresses the human desire 
that fish consumed from the Don River be acceptable for human consumption. 

8. Aesthetics 

This goal recognizes that many human perceptions of water quality are associated with 
aesthetics. Two of the prime face human senses of aesthetics are sight (with the image 
of "clear") and smell (with the image of "free from unpleasant odours). It specifically 
implies nutrient conditions (as the control of abnormal algal growths) and specific 
sources of unsightly wastes (spills, accidental discharges of industrial (dyes, etc.) and 
domestic wastes (CSO's, STP bypasses' cross-connection of sanitary wastes to storm 
sewer) as crucial elements required to maintain the aesthetics of flowing riverine water. 

9. Erosion and Flood Control 

This is a goal statement for the historical human safety and property value basis for the 
management of water quantity (peak flow rates and its mitigation). Alteration of natural 
flows have resulted from the removal of forests associated with European settlement. 
Attempts to control the flows include flood control reservoirs (storage for peak water 
volume), channelization (increased hydraulic capacity), and stormwater management 
ponds (storage for maintaining peak runoff rates the same in newly urbanized lands as 
previously in agricultural lands). 

'fl39.3 AI. 17 

10. Risk to Life in Valley Lands 

This goal is a more explicit statement of the safety of an individual human enjoying 
valley lands which may be subject to flooding. The previous goal (//9) is more general in 
its orientation. 

11. River Beds as Fish Habitat 

This goal statement overlaps with aesthetics. It is placed here because uncontaminated 
and unsoiled river beds are the key habitat for a balanced food web and for a self- 
sustaining fishery. 

12. Angling 

This goal recognizes that angling is highly valued by various members of society. But 
this goal has a larger importance than this solely. Preferred species of fish are an 
indicator of a diverse population of fish, a balance of ecosystem, and the supporting food 
web. Society's knowledge that angling is successful, ever though everyone does not 
participate, is an important component of the second goal. 

13. Enjoyment of Plants and Wildlife 

This goal reflects the ideal that a natural assemblage of birds, plants, mammals and fish 
are an indicator of an overall healthy ecosystem. It recognizes that many humans get 
enjoyment from visually observing these assemblages without physically intruding into 
the ecosystem. 

1^*. Wildlife and Waterfowl 

This goal statement acknowledges that humans obtain enjoyment both from terrestrial 
ecosystems and from wildlife and waterfowl. It acknowledges that terrestrial habitats 
are essential for wildlife and waterfowl. Whether the populations can be (i) self- 
sustaining within the watershed, (ii) self-sustaining by migrating to other watersheds; or 
(iii) human maintained (zoos, etc.) is species specific. It is information which requires 

i*139.3 A1.18 

further research before it can be stated in this type of a plan. This goal statement 
assumes that the Don River watershed will be urban for the 50 year period and that 
neither hunting of mammals nor trapping are permitted activities. 


The following section outlines a set of objectives which will assist in attaining the long- 
term, ecosystem based goals outlined in the previous section. 

The objectives are outlined as short-term objectives and long-term objectives. As noted 
previously, it is the intent of this Appendix that the goal statement would not change 
over time but that the statement of objectives would change as the plan is implemented 
or as new information becomes available. That is, the statement of objectives are 
relatively dynamic in their statement. 

The short-term objectives outlined below represent a mixture of measures for 
implementation and a statement of other information required to define the nature of 
the problem to be addressed. This mixture is required, as present knowledge available to 
this study team was not adequate to define short-term objectives which could be 


From this list of measures for implementation, the most effective ones were evaluated 
quantitatively in the Summary Report while many of the remainder were evaluated 
qualitatively. This listing was also used to assist in developing the implementation 
measures given in the Summary Report under the headings: 

o Immediate Actions (1989-1990); 

o Phase I (5-10 Year Time Frame); and 

o Phase II (Long-term; 10-50 Year Time Frame). 

General: Quality of Life Within Great Lakes Ecosystem 

1. Linkage to Great Lakes Ecosystem 

Short-Term Objectives Long-Term Objectives 

a) Define the linkages to Great Lakes a) Implement requirements of 

ecosystem based plan. 

'4 139.3 A 1.20 

Short-Term Objectives 

LonR-Term Objectives 

b) Define requirements of an ecosystem based 

b) Complete reduction of loads 

c) Augment definition of river water quality 
objectives from a RAP and whole lake 
point of view. 

d) Achieve partial reduction of loads for 
. nutrients (80% of NH3 and 50% of 

TP from STP) 

fecal coliforms (CSO's, stormwater) 


Suspended solids 

e) Improve fish/marsh habitat at mouth 
of Don River. 

2. Pride in Restored Don Valley Ecosystem 

a) Assess public perceptions and demands 

b) Establish diversity parameter or 
similar social survey instrument for 
assessing public "pride". 

a) Assess changing attitudes 
and demands of the public 

b) Update ecosystem based 
plan and other plans 
described below, as required 

3. Balance of Economic and Environmental Values 

a) Establish environmental quality goals 

b) Establish carrying capacity of Don 

River watershed for human populations 


a) Implement program to 
achieve goals 


Short-Term Objectives 

LonR-Term Objectives 

c) Establish economic goals and impacts 
on Don River Watershed 

d) Establish economic constraints 

e) Establish necessary plans to meet goals 
li. Quality of Life and Land Ownership 

a) Complete attainment of public lands 

b) Establish the type of ownership and 
collective management tools necessary 
to manage the valley system 

Public Health and Aesthetics 

5. Contact Non-Contact Recreation 

a) Obtain acceptance by 
private and public land- 
owners of tools necessary to 
manage the lands 

b) Implement the tools 

i) Assess achievability of swimming goal 
over the long-term 

a) Achieve objective for 
incidental contact 

b) Assess achievement of a goal for 
incidental contact over the short-term 

c) Establish technical objectives for a goal 
of incidental contact with water 

d) Implement necessary controls for "no 
lumps/waste flows" etc. 

b) Achieve objectives for 
swimming in selected ponds 
and reservoirs 

c) Possibly achieve swimming 
objective in all river waters, 
most of the time 

«f 139.3 

A 1.22 

Short-Term Objectives 

LofiR-Term Objectives 

e) Reduce bacterial loadings from priority 

f) Achieve contact recreation water quality 
objective (200 FC/lOO mL) in prime 
swimming areas (e.g., a few ponds/ 
reservoirs) some of the time 

6. Drinking Water 

Survey all present well water supplies 
to individual homes to ensure that they 
achieve drinking water objectives 

a) Evaluate need for changing 
objectives for incidental 
ingestion of surface water 

b) Establish water quality objectives for 
incidental ingestion of surface waters 
in the Don River Watershed 

b) Achieve water quality 
objectives for incidental 
ingestion, most of the time 

c) Achieve water quality objective for 
incidental ingestion in areas prone 
to such occurrences 

c) Evaluate need and/or feasi- 
bility of drinking water 
objective for water from 
reservoirs, in light of 
achievement of objectives 
related to bacterial control 

7. Fish Consumption 

a) Assess transmittable diseases; control 
all sources 

b) Assess chemical burden in fish from 
metals, radionuclides and SOC's 

a) Complete the assessment and 
determination of appropriate 
objectives, initiated for the 



Short-Term Objectives 

LonR-Term Objectives 

c) Differentiale fish burdens as to source 
of origin (implace pollutants, stormwater, 
sewage, agricultural runoff, other human 
activities in the watershed, and 
atmospheric inputs) 

b) Change chemical and 
biological parameters for 
assessing long-term objectives 
as new chemical data, new 
contaminants and/or new 
concerns are identified 

d) Assess contaminant burden in sediments of 
deposltional environment and determine 
the geochemical 

c) Attain long-term objectives 
by appropriate means 

e) Establish criteria for long term objectives 

f) Clean up (by dredging or other techniques), 
hot spots which cause significant 
contaminant bioaccumulation in fish or in 
the food chain 

8.0 Aesthetics 

a) Reduce total P loads to reduce periphyton 
and other abnormal algal growths 

b) Assess causes of unpleasant odours; 
realize that decay processes are the 
causes of some unpleasant odours but 
are an essential part of the ecosystem 

c) Reduce imputs of vegetation to river where 
organic matter is beyond the requirements 
of fish and a balanced ecosystem 

a) Attain a balanced ecosystem 
which generates natural odours 
even though they are 
unpleasant as a result of decay 

b) Return the river to a meso- 
trophic state rather than the 
present hypereutrohpic state 

c) Eliminate all sources of CSO's 
and industrial wastes 



Short-Term Objectives 

LonR-Term Objectives 

d) Reduce suspended solids/turbidity inputs 
by vegetating banks and achieving some 
reduction in suspended solids 

e) Control some CSO discharges (either 
on frequency or volume basis) and 
separate contaminated industrial discharges 
from storm sewer system 

d) Control all spills 

e) Control all stormwater 

f) Control turbidity discharges from all new 
developments and redeveloped areas 

Public Safety 

9. Erosion and Flood Control 

a) Vegetate lands, obtain setbacks and 
conduct other passive measures to 
minimize erosion at active sites 

b) Continue to assess which erosion scars 
are natural and hence those for which 
human intervention will not be overly 

c) Establish that redevelopment sites such 
as the St. Lawrence Square will be 
subject to flooding at some point in the 
future. Floodproof buildings to maintain 
their stability. Implement appropriate 
evaculation plans 

a) Minimize erosion 

b) Change erosion control 
policies, as scientific/ 
geomorphological under- 
standing of the causes of 
erosion increases 

c) Remove dwellings from areas 
which are too close to natural 
erosional areas 



Short-Term Objectives 

LonR-Term Objectives 

d) Change channelization construction designs 
to take account of fisheries objectives 

e) Establish policies to increase infiltration 

of rain water where soils conditions permit, 
as redevelopment occurs 

f) Implement erosion control measures in small 

10. Risk to Life in Valley Lands 

a) Assess risk to life due to use and 
enjoyment of valley lands 

a) Implement long-term 

b) Establish long-term objectives 
Fisheries and Riparian Habitats 
1 1 . River Beds as Fish Habitat 

a) Replace concrete lined channels as 
opportunities arise 

a) Replace all past concrete- 
lined, channelized river 
beds with stable structures 

b) Reduce algal growth using objectives 
laid out above 

c) Implement CSO/industrial/stormwater 
controls to improve habitat 

d) Improve canopy cover 

which provide fish habitat, 
bottom vegetation, and hy- 
draulic transport capabilities 

b) Achieve nutrient control 


A 1.26 

Short-Term Objectives 

LonR-Term Objectives 

12. Angling 

c) Complete control of CSO, 
industrial and stormwater 

a) Establish smallmouth bass and other 
appropriate species as an indicator of 
a quality guild of warmwater species 
of fish 

a) Develop balanced food web for 

b) Carry out necessary habitat 

b) Assess long-term cold-water objective 

c) Complete indepth HSl evaluation initiated 
in this study 

c) Control all contaminant 
inputs to level necessary 

d) Establish fish management plan 

e) Maintain food sources transported from 
upper watershed to lower watershed for fish 

f) Reduce frequency of spills 

d) Develop the balanced 
ecosystem required for a 
smallmouth bass guild, and 
possibly for a cold-water fish 

e) Manage human fishing pressure 

g) Reduce toxicity of river water 

h) Audit performance of plan using IBI 

h) Establish fishing pressure limits to 
sustain a fishery 

't 139.3 


13. Enjoyment of Plants and Wildlife 

Short-Term Objectives 

a) Assess public perception of requirements 
for enjoyment of a healthy riverine/ 
valley environment 

b) Establish a parameter for assessing 
enjoyment of the public 

Long-Term Objectives 

a) Assess changing attitudes 
and needs of the public 

b) Audit the success of 
established plans 

c) Initiate revegetatlon 
lU. WildUfe and Waterfowl 

a) Develop requirements for a balanced 
wildlife regime in an urban dominated 
valley system, taking account of existing 
core areas (e.g., Maple MNR lands, 
Science Centre, conservation lands) 

b) Develop a plan 

c) Initiate revegetation 

d) Augment habitat in existing areas 

a) Implement complete 

b) Protection of habitat and 
wildlife/waterfowl against 
vandalism, illegal hunting and 

e) Develop policing necessary to preserve 
and protect existing areas against 
vandalism etc. 


A 1.28 


Environmental Pathways Modelling 

as a Tool for Assessing the 

Response of Fisheries Resources and of 

Human Healtfi to Water Quality 

Control in the Don River Watershed 

APPENDIX 2: Environmental Pathways Modelling as a Tool for Assessing the 

Response of Fisheries Resources and of Human Ffealth to Water 
Quality Control in the Don River Waterdied 

A2.1 Approadies to Assessment 

Water quality criteria have been established for the protection of aquatic life and 
drinking water sources. Values established in Canadian and American jurisdictions are 
summarized in Table A2.1. 

Other approaches for assessing salient features of water quality include chemical impact 
on humans and chemical burdens in fish. Chemical burdens in fish result from their 
consumption of water and food from river waters and sediments containing heavy metals 
and organic compounds. These substances may only bioaccumulate in fish or may be 
toxic to both humans and/or the fish. Chemical impacts to humans can be assessed using 
a health assessment approach, or a comparative approach in which ingestion of the river 
water is compared to normal consumption. The health assessment approach evaluates 
the possibility of cancer development and other humein health effects due to humans 
drinking the water and consuming fish from the river. The comparative approach 
compares the mass of contaminant in ingested water to the mass consumed from all 
dietary sources. 

The use of both approaches (fish impact; human health) were initiated in this study. The 
mathematics of the approaches are summarized in project files as a position paper. An 
overview of the approach are now described to show the quantitative linkage between 
water quality control and fisheries/human health. 

A2.2 Environmental Patiiways 

Environmental pathways modelling is the master tool used for both approaches. It is a 
steady-state, mass balance approach for predicting the release rate of chemicals to the 
environment, the resultant concentrations in various biota and environmental 
compartments, and the rate of uptake by, and the impact on humans from carcinogens, 
radionuclides and other substances. 

''139.3 A2.1 


bospcnded .nalter ihould i 

wye' (n 


reading by more 

20 ug/L as in-ionized torn 



10 mg/L^ 

Geometric me»n det 
100 per 100 mL lor 
ol «Iter samplei 

25 ug/L^ (umiltered) 
30ug/L (unflltered) 

Increase of 10 mg/L »hen 


background is less or 
equal to 100 mg/L, or 
increase of 10% above 

o( depth of 
point for ph 

back^rouod when background 
is greater than 100 mg/L 

25 to lOOug/L' 

20 ug/L as i*i-ionized 

&0 to 2,300 ug/L as total 
ammonia depending on pH 
iTui temperature (e<fials 
0.7 to 35 ug/L un-ionlied; 
e.g., 23 ug/L at pH » and 

0.0« mg/L 
Corxrentrat i^ 

10 mg/L^ 

Geometric mean density Geometric mean t 

east 3 sample 
over a JO-day period 
should be l<is than 200 
per 100 mL^ 

2 ug/L 

10 ug/L' 
200 ug/L^ 

100 ug/L* 

0.1 ug/L (unfiltered) 
5 mg/L' 

least 5 samples over a 
30-day period should be 
less than 200 per 100 mL 

6 ug/L' 

7 ug/L' 

30 ug/L 

3 ug/L (pH L 6.3) 
100 ug/L (pH GEÉ.3) 

25 to 100 ug/L' 

0.7 lo370ug/L(un-,oniied) 
depending on pH. temperature, 
species sensitivity and is based 
on l-ho^fl- and li-day averages 
(e.g., n^ai. i<-day average at 
pH S and 10°C for salmonids .s 
23 ug/L) 


Geometric mean d< 

least 5 samples ove 

period should be less than 126 

per 100 mL for E^coMand 33 

per 100 mL (or enterococci 

21 ug/L' as l^y average 
3*1 ug/L as 1-hour average 

7.7 ug/L' as «Hlay average 
200 ug/L-" as 1-hour average 

190 ug/L' as l-day average 
210 ug/L' as 1-hour average 

130 ug/L (pH between 6.3 and 
9.0) as ii-day average 
930 ug/L (pH between 6.5 and 
9.0) as 1-hour average 

0.012 ug/L as «-day average 
2.<i ug/L as 1-hour average 

Individual petrochemicals 
should not exceed 0.01 of 96- 
hour LC50o( important 
sensitive species. Surface 

Penlachloro- 0.5ug/L'^ 




2.4,5 -T None f*>"« 

Atrazine None None 

BOUj None - see dissolved oxygen 

Dissolved 1.7 to 61% of saturation must «7 10 1 


15.6 ug/L' 

i 9.3 mg/L dependent < 

No objective for prole 

life Guidelines based on nuisance algal gro« 

> objective for protection of aquatic life. Maximum acceptable concentra 
sed on a hardness of 200 rn^/L (CaCO,). Oiterion is deper>dmt on hard", 
•ntative limit proposed by UG (1977). 

• Quality Objectives; UOt (19g<.) 

Canadian *al'r Quality Guidelines; rjivironrnent Canada (1981). 



U.i. r.l'A Water Quality Criteria; U.S. r.l'A (1976). 

U.S. I. l'A (1986); most objectives allow lor one e, credence every 

Orjft OOjective. proposed 1986. 
l'ronus.d. McKrr-i jl. (1981i) 

1 and/or excessive plan 

A2.2. 1 Information Needed to Develop an Environmental Pathways Model 

The block diagram and mass transfers involved in an environmental pathways model 
relevant to fish in the Don River is given in Figure 7.1 in the main body. Basically, to 
apply it, the following information is required. 

(1) which particular chemicals are to be considered; 

(2) where these particular chemicals originate in the community and the 
quantities that are disposed of from various sources; 

(3) the particular pathway followed by each chemical and its fate in passing 
through particular waste handling and treatment systems; 

(<f) define which humans are likely to be exposed to the highest dose from these 

chemicals; and 

(5) define a series of environmental transport pathways that will allow the 

calculation of an impact to the population exposed to the released chemicals. 

A2.2.2 Human Health 

The general population, members of the general public whose habits expose them to the 
chemicals through body contact or food consumption or occupational workers are 
candidates for assessing the effects of water quality on human health. 

For various occupational workers in waste handling and treatment facilities, potential 
human health parameters calculated for various work groups based on their job duties. 
From these calculations, the maximally exposed group, or critical group can be 
identified. Similarly, for members of the general public, specific persons whose fishing 
and incidental ingestion of Don River water result in their exposure to the chemical(s) of 
concern would be evaluated. 

On-site field investigations using structured observational techniques (a sociological 
approach in which specific behavioural data are collected with minimal knowledge by or 

'flSS.S A2.2 

influence on the human subject (Whyte, 1977)) can be used together with interviews in 
the watershed, to identify the most probable highly exposed individuals or occupational 
critical groups. These are employees whose working habits, occupational environment, 
proximity to possible chemicals, exposure duration and exposure geometry would place 
them at greater danger to exposure to the chemicals than other employees. 

Members of the general public who should be considered are those who may enter high 
exposure areas through such activities as recreation, wading, or fish consumption. 

A2.2.3 Environmental Pathways for Urban Runoff and Wastewater Treatment 

The main pathway associated with thse sources are surface waters. Contamineints of 
concern in Figure 7.1 are found in urban and rural stormwater runoff. Inputs to the 
wastewater treatment system shown in Figure 7.1 are derived from hospitals, 
universities, industries and other institutions. Input of leachate from a landfill site 
containing chemicals that may have leached from household garbage and incineration ash 
may also be a source, but may not be significant in the Don River Case. The impact of 
old dumps upon Don River water quality requires further assessment. 

Chemicals released to the environment are dispersed and transported through various 
environmental pathways. For the purpose of human health relevant to the general 
population, possible exposure pathways are: 

1. External exposure from: 

o immersion in the airborne plume, 
o contaminated ground; 

2. Inhalation; and 

3. Ingestion of aquatic foods. 

Other potential pathways include immersion in contaminated water and ingestion of 
terrestrial foods (crops, livestock). 

«f 139.3 A2.3 

For occupational workers, exposure occurs through the external and inhalation pathways: 

1. External exposure from: 

o immersion in the airborne plume, 

o exposure to gamma radiation from waste at the workplace; and 

2. Inhalation, primarily of dust, aerosols and volatile chemical in the working 

For carcinogens, external exposure is generally not a concern and hence is disregarded in 
environmental pathways models. These pathways are only relevant where the substances 
of concern are radiochemicals handled in municipal treatment plans such as C-H and 
H-3. These substances are found In human wastes and were assessed in a previous study 
(BEAK, 1986). Carcinogens and other substances are mainly of concern herein. 

Environmental dispersion pathways from the WWTP may include atmospheric releases 
from the burning of sludge (If present), the release of chemicals like CO2 in the sludge 
digester and the release of volatile organics In aerosols from aeration tanks, as well as 
the release to surface water of the treated water. The atmospheric release pathway 
considers human exposure arising from inhalation, and external exposure to both the 
plume and ground deposited material. The aquatic pathway considers exposure from both 
the consumption of fish and water. 

A2.3 Perspective for Stormwater Management and Water Quality Control in the 

Don River 

A2.3.1 Development of Levels of Protection 

A practical question of whether protection of aquatic biota or human health should be 
used as the basis for evaluating response of water quality developed in this study. It also 
poses the question of whether a gradient of fishable-swimmabie-drinkable, or of 
dbrinkable-swimmable-fishable is a more stringent gradient for purposes of water quality 

^139.3 A2.4 

These questions can be illustrated by comparison of (i) PWQO's of MOE or CCREM's for 
protection of aquatic life to (ii) Water Quality Criteria based upon drinking water 
limits. The values that result, are as follows: 


Typical Don 
River Cone. 

10 ug/L 


(Protection Aquatic 

Life, Table 7.1) 

PWQO Drinking 

Water Considerations 



2-6 ug/L 

1 mg/L 


25-360 ug/L 

30 ug/L 



7 ug/L 

7-25 ug/L 

50 ug/L 


8-37 ug/L 
upon hardness 

60-180 ug/L dependent 

n.^t ug/L 


W ng/L 

100-200 ng/L 

IfO ng/L 


12 ug/L 

20 ug/L (fish) 
2 ug/L (zooplankton) 

170 mg/L 

In establishing approximate target levels, essential element considerations for human 
health will rarely be the criteria used for elements such as copper, chromium and zinc. 
Rather, it is expected that humans will get these essential elements from normal diets. 
Then water quality will be protected for the most sensitive use: protection of aquatic 


For other elements, however, such as nickel, and mercury, guidelines based upon human 
health effects may be as strict as, or more strict than, protection of aquatic life. The 
evolution of the pathways assessment tools approach may assist in proritizing the value 
system used in evaluating the effectiveness of response. 

In this study, the levels of protection approach was developed for specific end uses 
(swimming, fishing, aesthetics). These questions and an ecosystem perspective were used 
as the basis for developing these "levels". The overlay of which human benetical end use 
or ecosystem component (fish) is more important was left for further analyses. 



A2.3.2 Impacts of Water Quality Control 

The loadings analysis for SS, TP, ammonia, Cu, Zn, cind Pb established that the most 
effective water quality control measures in the Don River are wet ponds or equivalent in 
urbem areas, flow reduction techniques such as Infiltration in redeveloping areas, and 
improved CSO and STP control. 

The effectiveness of these control efforts for improvement of human health can be 
assessed once appropriate loading riverine concentration models are developed. It would 
be useful to do this, but such activity is beyond the time frame available to this study, 
since loadings-receiving water models for key contaminants such as arsenic were not 
developed in this study. 

"139.3 A2.6