PRELIMINARY EVALUATION OF
CHANNEL CHANGES DESIGNED TO
RESTORE FISH HABITAT
MONTANA STATE LIBRARY
S627.12 M41pc.1 Hunt
Preliminary evaluation ot channel change
MSI «*2!'82
FEB 9 1983
JUN -51991
3 0864 00004017 3
MAR 1 g 2010
PRELIMINARY EVALUATION OF
CHANNEL CHANGES DESIGNED TO
RESTORE FISH HABITAT
Prepared for the
STATE OF MONTANA
WBm mmms collection
24 1978
MONTANA STATE LIBRARY
930 E [yndale Av$.
Helena, Montana 5960]
DEPARTMENT OF HIGHWAYS
PLANNING AND RESEARCH BUREAU
and
DEPARTMENT OF FISH AND GAME
ENVIRONMENT BUREAU
in cooperation with the
U.S. DEPARTMENT OF TRANSPORTATION
FEDERAL HIGHWAY ADMINISTRATION
The opinions, findings and conclusions expressed in this
publication are those of the authors and not necessarily
those of the Montana Department of Highways, Department
of Fish and Game or the Federal Highway Administration
Prepared by
William A. Hunt
DEPARTMENT OF CIVIL ENGINEERING
and
Richard J. Graham
COOPERATIVE FISHERIES UNIT
MONTANA STATE UNIVERSITY
Bozeman, Montana 59715
October 31 , 1972
Digitized by the Internet Archive
in 2015
https://archive.org/details/preliminaryevalu1972hunt
ABSTRACT
An evaluation of the fish habitat in two meanders constructed in the
Clark Fork River west of Drummond, Montana, shows the hydraulic, topographic
and fish population characteristics of these artificial meanders to be simi-
lar to those found in comparable natural sections of the river. A design
procedure based on observations of meanders in stream being altered is
recommended.
-ii-
ACKNOWLEDGEMENTS
This study, MHD Project No. 7921, was conducted for the Montana State
Highway Commission in cooperation with the Department of Transportation,
Federal Highway Administration.
The successful execution of this study was due to the valuable assistance
received from many individuals of the Montana State Highway Department, the
Montana Fish and Game Department, the Department of Civil Engineering and
Engineering Mechanics of Montana State University, and the Bozeman Unit of
the Bureau of Sport Fisheries and Wildlife. The investigators are particu-
larly indebted to Ronald G. Marcoux, Fisheries Division of the Montana
Fish and Game Department, Missoula, for conducting the fish population surveys,
to Messrs. Rodger C. Foster and Michael Watson, Graduate Research Assistants
in Civil Engineering, MSU, for obtaining and assisting the analysis of the
hydraulic and topographic field data, and to Mrs. Ed Reeves, Drummond, for
observing the river gage readings.
-iii-
TABLE OF CONTENTS
Page
Abstract ii
Acknowledgements iii
List of tables v
List of figures . vi
1. INTRODUCTION 1
2. BASIS OF EVALUATION 4
3. RIVER CHARACTERISTICS 6
3.1 Description of area 6
3.2 River discharge records 6
3.3 Constructed meanders 8
3.4 Natural meanders 10
4. EVALUATION METHODS 11
4.1 Hydraulics and topography 11
4.1.1 Discharge measurements 11
4.1.2 Water surface profiles 13
4.1.3 Channel cross-sections 14
4.1.4 Bed material samples 15
4.1.5 Water turbidity and suspended sediment samples ... 15
4.2 Fish population survey 16
5. PRESENTATION AND DISCUSSION OF RESULTS 17
5.1 Hydraulics and topography 17
5.1.1 Quantitative characteristics 19
5.1.2 Qualitative characteristics 20
5.1.3 Results of intensive studies 21
5.1.3.1 Channel topography 22
5.1.3.2 Channel hydraulics 23
5.2 Fish population estimates 27
5.3 Bed materials 30
5.4 Suspended sediment and turbidity 31
5.5 Other conditions observed 34
6. CONCLUSIONS AND RECOMMENDATIONS 37
6.1 Conclusions 37
6.2 Discussion 37
6.3 Recommendations 38
6.3.1 Design procedure 38
6.3.2 Future studies 40
LITERATURE CITED 42
APPENDIX 43
-iv-
LIST OF TABLES
Table No. Page
1. Channel change summary 2
2. Clark Fork River discharge, Drummond 7
3. Flint Creek discharge . . . 8
4. Length, slope of natural meanders 10
5. Schedule of data observed on meander channels .... 12
6. Meander characteristics 18
7. Depth-velocity characteristics of meander sections . . 25
8. Fish capture, summer 1971 28
9. Fish population estimates for Enman and Hazel
Marsh Meanders 29
10. Analysis of bed material 32
11. Analysis of suspended sediment and turbidity 33
-v-
LIST OF FIGURES
Fig. No. Page
1. Project location map A-l
2. Weaver Meander, aerial photo A-2
3. Hazel Marsh Meander, aerial photo A-3
4. Weaver Meander, construction plan A-4
5. Hazel Marsh Meander, construction plan A-5
6. Constructed channel cross-sections A-6
7. Downstream No. 1 Meander, aerial photo A-7
8. Downstream No. 2 Meander, aerial photo A-8
9. Nelson Meander, aerial photo A-9
10. Enman Meander, aerial photo A-10
11. Stage-discharge rating curve A-ll
12. Plan, profile, cross-sections for Downstream
No. 1 Meander (Nl) A-12
13. Plan, profile, cross-sections for Downstream
No. 2 Meander (N2) A-13
14. Plan, profile, cross-sections for Nelson
Meander (N3) A-14
15. Plan, profile, cross-sections for Enman
Meander (N4) A-15
16. Plan, profile, cross-sections for Weaver
Meander (CI) A-16
17. Plan, profile, cross-sections for Hazel Marsh
Meander (C2) A-17
18. Topography of Hazel Marsh Meander, as built 11/69 . . A-18
19. Topography of Hazel Marsh Meander, existing 3/23/72 . A-19
20. Topography of Enman Meander, existing 3/25/72 .... A-20
21. Velocity distribution pattern, Hazel Marsh Meander . . A-21
22. Velocity distribution pattern, Enman Meander A-22
23. Transverse velocity distributions A-23
24. Size distribution of bed materials A-24
25. Point bar deposits, Hazel Marsh Meander A-25
26. Point bar deposits, Enman Meander A-26
27. Stream flow cross-overs, Enman Meander A-27
28. Rock jetty, Enman Meander A-28
29. Stream flow cross-overs, Hazel Marsh Meander A-29
30. Flow next to rip-rap, Hazel Marsh Meander A-30
-vi-
PRELIMINARY EVALUATION OF CHANNEL CHANGES
DESIGNED TO RESTORE FISH HABITAT
1. INTRODUCTION
Preliminary plans for the construction of 15 miles of Interstate Highway
1-90 west of Drummond called for channel changes which would shorten the
Clark Fork River by approximately 1800 ft. Based on the preliminary plans
and the authority of the Stream Preservation Law enacted by the Montana
Legislature in 1965, the Montana Fish and Game Commission recommended that
provisions be made for preserving the total length of the river in this
15-mile section of highway. The Montana Highway and the Fish and Game
Commissions mutually agreed that a workable solution would be to construct
two artificial meanders with combined lengths sufficient to recover the
1800 ft of stream length. The location of the project and its channel change
sections are shown in Fig. 1.— The two meanders, shown in Figs. 2 and 3 and
constructed at the locations indicated in Fig. 1, have approximate meander
lengths of 2600 ft. each and replace existing channel lengths of 1500 ft
each. The upstream meander (C2) is referred to as the Hazel Marsh Meander;
the downstream (CI) , the Weaver Meander .
A summary of the channel changes in this section of highway given in
Table 1 includes original and new stream lengths, change in lengths and mean
values of old and new slopes (based on difference in channel bed elevations
at each end divided by stream length) . The excavation quantities required
for constructing the meanders are also given in Table 1.
The construction of the two meanders was completed in the fall of 1969.
The runoff in the spring of 1970 was the first high discharge passing through
these sections. Acknowledging the possibility of constructing similar meanders
for preserving the length of trout streams adjacent to future highway projects,
the Montana Highway Commission and the Federal Highway Administration requested
an evaluation of the artificial meanders. A study was initiated on December
1, 1970 to evaluate channel changes designed to restore fish habitat. The
1/ All figures are in Appendix A
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evaluation is based on (1) the hydraulic characteristics of the constructed
meander channels and (2) the acceptability of the constructed meander channels
as life-supporting habitat by species of fish found in the Clark Fork River
near Drummond. Studies of the hydraulic characteristics were conducted by
the Department of Civil Engineering and Engineering Mechanics of Montana State
University; the fish population studies by the Fisheries Division of Montana
Fish and Game Department in cooperation with the Bozeman Unit of the U. S.
Bureau of Sport Fisheries and Wildlife.
2. BASIS OF EVALUATION
The preliminary evaluation was made by comparing the hydraulic character-
istics and fish populations in existing natural meanders with those in the
constructed meanders.
The hydraulic character of river for fish habitat is determined by the
following factors: water surface slope, bed profile, velocity, thalweg (line
connecting the deepest points of the channel), and pool-riffle periodicity.
The ratio of the thalweg to the down valley distance is used as an index to
the susceptibility of a stream to provide fish habitat and is greater than
one for all streams. The greater this ratio, the more pools per 1000 ft of
stream length. The pool-riffle periodicity is given as the ratio of the
distance between riffles (shallow, fast-water sections) to the average stream
width.
Criteria for defining a meander are given by Leopold and Langbein (1966)
and Leopold, Wolman and Miller (1964). The former report indicates meanders
are characterized by a ratio of meander length to average radius of curvature
in the bend of 4.7. The latter consider a stream segment to be considered
meandering if its sinuosity (ratio of channel length to down valley distance)
is greater than 1.5.
The studies of stream alterations on fish habitat and population reported
by Elser (1968), Johnson (1964), Swedberg (1965), and Whitney and Bailey
(1959) give quantitative data on the reduction of fish population caused by
highway construction but do not present sufficient hydraulic data to determine
design criteria. Lewis (1969) indicates that cover (brush, overhanging
vegetation, undercut banks, and dead submerged portions of bank vegetation)
and velocity are the two most significant physical factors affecting variation
in trout populations in streams. Although optimum pool velocities were not
indicated, the velocities in the study range from 0.30 to 1.67 fps. Elser
(1968) also gives data on channel measurements from Little Prickly Pear
Creek in altered and unaltered sections indicating pool-riffle perodicities
ranging from 4 to 9 and ratios of the thalweg to down valley distance ranging
from 1.18 to 1.66 for unaltered sections. Leopold and Langbein (1966) indi-
cate the spacing of successive riffles is ordinarily from 5 to 7 times the
width.
-4-
The studies of Elser (1968) , Johnson (1964) and Swedberg (1965) were
conducted on Little Prickly Pear Creek whose mean monthly discharges for
July, August and September, 1965, were 92, 52, and 86 cfs, respectively.
The mean discharges of the Clark Fork for the days observed in July,
August, and September, 1971, were 245, 267, and 520 cfs, respectively.
Because of the differences in the magnitudes of the average flows and the
average stream widths of the two streams, it was determined that the charac-
teristics of the constructed meander on the Clark Fork should be compared
with those of a natural meander of the same river.
The water surface slope, bed profile, average velocity, cross-sectional
area, samples of bed material and fish population data from natural meander
sections are compared with similar data taken in the constructed meanders.
The thalweg indicies, velocities, and pool-riffle frequencies found will
also be compared with those indicated in the literature cited above.
-5-
3. RIVER CHARACTERISTICS
3.1 Description of area
The Clark Fork River is formed by the confluence of Willow Creek and
Silver Bow Creek approximately 5 miles east of Anaconda. It flows northerly
for nearly 35 miles to Garrison then northwesterly for 25 miles through
Drummond where it turns and flows more westerly through the Garnet-Bearmouth
area. Flint Creek is the only perennial tributary with a significant flow
entering the Clark Fork in the portion studied; it flows into the Clark Fork
at Drummond, between the natural meanders upstream and the Hazel Marsh Meander.
Numerous intermittent tributaries feed the Clark Fork from both sides of the
valley .
Between its origin and Garrison the Clark Fork flows through a broad
lowland bordered by low terraces which slope gently upward to the mountains
on either side. At Garrison the river turns sharply to the northwest and
flows through a series of deep gorges interspersed with rolling uplands and
well-drained slopes. The present flood plain west of Drummond is made up
of alluvial deposits of sand and gravel.
The section of the Clark Fork River studied has an average gradient of
5 to 10 ft per mile and is limited in its lateral meandering by the slope of
the sides of the valley. These features classify it as a mountainous stream.
Valley streams are characterized by gradients less than 2 to 3 ft per mile
flowing in broad valleys allowing great latitude in the meandering.
The vegetation in the Clark Fork River Valley west of Drummond consists
of native bunch grasses, pine, fir, spruces, aspen, willow and alder. The
aspen, willow, and alder are predominant along the river banks.
3.2 River discharge records
Discharge records for the upper reaches of the Clark Fork River are
very meager. The only discharges of record consist of daily readings for
the months of April, May and June for 1968, 1969, 1970, and 1971 plus the
discharge measurements taken as part of the data for this study. The former
were taken for the U. S. Weather Bureau; the latter were taken monthly by
a local observer and also on days when hvdraulic and topographic field data
-6-
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were taken. The discharge data taken during the study period are given in
Table 2.
The discharge of the Clark Fork in the proximity of study section is
measured by a USGS wire-weight stage gage located at Drummond on the south
side of the bridge on U. S. Highway 10A and is downstream from the mouth of
Flint Creek. The maximum flow of record is 4450 cfs on June 2, 1969. The
minimum discharge recorded during 1971 was approximately 125 cfs.
The discharge record for Flint Creek consists of nine monthly observa-
tions above Willow Creek (not same creek previously mentioned) from October,
1971, through June, 1972, and three at the mouth of Flint Creek at Drummond;
these are given in Table 3.
Table 3. Flint Creek Discharge
Flint Creek Discharge, cfs
Date
At Willow Creek
At Drummi
10/13/71
137
11/14/71
127
12/14/71
114
1/12/72
93
2/15/72
90
3/14/72
188
4/13/72
172
218
5/15/72
432
419
6/13/72
377
317
The Willow Creek gaging station for Flint Creek is approximately five
miles above the junction of Flint Creek with the Clark Fork River and was
established in October, 1971 by the USGS. The Drummond gaging station for
Flint Creek was installed in April, 1972.
3.3 Constructed meanders
The plans for the Hazel Marsh and Weaver Meanders are shown in Figs. 4
and 5 respectively. The typical channel cross-section in the curved portions
-8-
of both meanders is shown at the top of Fig. 4 and in Fig. 6a with the deep
portion of the channel oriented to the outside of the curve. The field
notes for staking the construction indicate the cross-sections in the zone
of transition (where the deep portion of the channel crossed from one side
to the other) was as shown in Fig. 6b. The outside of the curves were armored
with type "B11 rip-rap whose average piece was in excess of 0.5 cu yd with
some pieces as large as 3 to 4 cu yd. The armored areas are shown in Figs.
4 and 5.
The planimetric configurations of the constructed meanders were estab-
lished by locating old meander channels of the river in the areas selected
from aerial photographs. Gravel deposits and the patterns of vegetation
noted in the photographs and by field reconnaissance provided sufficient
evidence to relocate the old meander channels.
The hydraulic design criteria used for these meander channels was not
established in this study. Attempts to determine any formal design procedure
included a search of the field notes and the files in the Hydraulic Section
of the Montana Highway Department. From discussions with the engineers in
charge of laying out the meanders it was learned that the cross-sections in
the constructed channels were designed in the field with the following
provisions :
a. high-water stream width approximately equal to that in the natural
channels,
b. maximum depth approximately equal to that in the natural channels,
c. deep flow area concentrated along outer bank of curve,
d. steep bank at outside of curve with gradual slope toward inside, and
e. constant slope along the centerline of channel.
The first four provisions were based on observations of sections of the
natural channel. The calculations for the channel hydraulics were not estab-
lished and design flow data were not available for this evaluation study.
As shown in Table 1, the Hazel Marsh Meander C2 is 2600 ft long with
a fall of 9.5 ft per mile. The original length of this reach was 1460 ft
and its fall was 17 ft per mile. The Weaver Meander CI is 2615 ft long
with a fall of 7.5 ft per mile. The original length of this reach was 1550
ft and its fall was 12 ft per mile.
-9-
3.4 Natural meanders
Four natural meanders initially were selected for study from aerial
photographs (scale 1:4800) of the Clark Fork River taken by the Montana
Highway Department on October 30, 1970. Tracings of the two constructed
meanders were superimposed on tracings of natural meanders to determine
which natural meanders were most geometrically similar to the constructed
ones. Two of the natural meanders selected were located downstream and
two upstream from the constructed meanders (see Fig. 1) . The natural
meanders are shown in Figs. 7, 8, 9, 10. The length and slope for each
are given in Table 4. The length listed is the total length of the control
section and extends beyond the individual meander curves.
Table 4. Length, slope of natural meanders
No. Name Length, Slope,
ft ft/mi
Nl D/S#l 2200 9
N2 D/S//2 2050 10.5
N3 Nelson 1600 7
N4 Enman 1550 7
-10-
4. EVALUATION METHODS
The methods used for the preliminary evaluation of the constructed
meanders required field observations and measurements for obtaining data on
the hydraulics and topographic characteristics and the fish population
estimates in both the natural and constructed meanders .
The hydraulic, topographic and fish population data obtained for each
meander are indicated in Table 5 along with their project reference names,
aerial photograph numbers, land ownership and legal land descriptions. The
designations I and II on water surface profiles and channel cross-sections
indicate that these data were obtained at two different times as discussed
in subsequent sections.
4.1 Hydraulics and topography
The principal hydraulic data observed were river discharge, water sur-
face profiles, and transverse velocity distributions. Isolated samples of
bed material, turbidity, and suspended sediment were obtained for comparison
purposes. The principal topographic data were channel cross-sections.
Transverse velocity distribution data were taken simultaneously with the
channel cross-sections. The river discharge measured by the stage recorder
at Drummond was recorded each day any observations were made. Attempts were
made to measure bed load transport rates at selected points in the river by
employing portable sediment traps designed in the laboratory. As these
devices proved unreliable and unmanageable, it was mutually agreed by the
principal investigator and the Montana Highway Research Engineer to forego
the observations of sediment transport rates.
The methods used for obtaining the above-listed data are discussed more
fully in the following paragraphs. The results of the hydraulic and topo-
graphic studies are presented graphically in Figs. 12 through 23 inclusive
found in Appendix A and discussed in Section 5.
4.1.1 Discharge measurements
The discharges occurring during the field measurements were obtained
from the readings of the stage gage at Drummond and the USGS stage-discharge
-11-
v.-
£ I
MSI msi*82
FEB 9 1983
JUN -51991
MAR 1 8 2010
MONTANA STATE LIBRARY
S 627.12 V41p c.1 Hunt
Preliminary evaluation of channel change
3 0864 00004017 3
PRELIMINARY EVALUATION OF
CHANNEL CHANGES DESIGNED TO
RESTORE FISH HABITAT
24 1978
MONTANA STATE I IBR*.RY
Prepared for the 930 e Lyndsls Av.?
STATE OF MONTANA
Helena, Montana 5360:
DEPARTMENT OF HIGHWAYS
PLANNING AND RESEARCH BUREAU
and
DEPARTMENT OF FISH AND GAME
ENVIRONMENT BUREAU
in cooperation with the
U.S. DEPARTMENT OF TRANSPORTATION
FEDERAL HIGHWAY ADMINISTRATION
The opinions, findings and conclusions expressed in this
publication are those of the authors and not necessarily
those of the Montana Department of Highways, Department
of Fish and Game or the Federal Highway Administration
Prepared by
William A. Hunt
DEPARTMENT OF CIVIL ENGINEERING
and
Richard J. Graham
COOPERATIVE FISHERIES UNIT
MONTANA STATE UNIVERSITY
Bozeman, Montana 59715
October 31 , 1972
ABSTRACT
An evaluation of the fish habitat in two meanders constructed in the
Clark Fork River west of Drummond, Montana, shows the hydraulic, topographic
and fish population characteristics of these artificial meanders to be simi-
lar to those found in comparable natural sections of the river. A design
procedure based on observations of meanders in stream being altered is
recommended.
-ii-
ACKNOWLEDGEMENTS
This study, MHD Project No. 7921, was conducted for the Montana State
Highway Commission in cooperation with the Department of Transportation,
Federal Highway Administration.
The successful execution of this study was due to the valuable assistance
received from many individuals of the Montana State Highway Department, the
Montana Fish and Game Department, the Department of Civil Engineering and
Engineering Mechanics of Montana State University, and the Bozeman Unit of
the Bureau of Sport Fisheries and Wildlife. The investigators are particu-
larly indebted to Ronald G. Marcoux, Fisheries Division of the Montana
Fish and Game Department, Missoula, for conducting the fish population surveys,
to Messrs. Rodger C. Foster and Michael Watson, Graduate Research Assistants
in Civil Engineering, MSU, for obtaining and assisting the analysis of the
hydraulic and topographic field data, and to Mrs. Ed Reeves, Drummond, for
observing the river gage readings.
-iii-
TABLE OF CONTENTS
Page
Abstract ii
Acknowledgements iii
List of tables v
List of figures vi
1. INTRODUCTION 1
2. BASIS OF EVALUATION 4
3. RIVER CHARACTERISTICS 6
3.1 Description of area 6
3.2 River discharge records 6
3.3 Constructed meanders 8
3.4 Natural meanders 10
4. EVALUATION METHODS 11
4.1 Hydraulics and topography 11
4.1.1 Discharge measurements 11
4.1.2 Water surface profiles 13
4.1.3 Channel cross-sections 14
4.1.4 Bed material samples 15
4.1.5 Water turbidity and suspended sediment samples ... 15
4.2 Fish population survey 16
5. PRESENTATION AND DISCUSSION OF RESULTS 17
5.1 Hydraulics and topography 17
5.1.1 Quantitative characteristics 19
5.1.2 Qualitative characteristics 20
5.1.3 Results of intensive studies 21
5.1.3.1 Channel topography 22
5.1.3.2 Channel hydraulics 23
5.2 Fish population estimates 27
5.3 Bed materials 30
5.4 Suspended sediment and turbidity 31
5.5 Other conditions observed 34
6. CONCLUSIONS AND RECOMMENDATIONS 37
6.1 Conclusions 37
6.2 Discussion 37
6.3 Recommendations 38
6.3.1 Design procedure 38
6.3.2 Future, studies 40
LITERATURE CITED 42
APPENDIX 43
-iv-
LIST OF TABLES
Table No. Page
1. Channel change summary 2
2. Clark Fork River discharge, Drummond 7
3. Flint Creek discharge . . . . 8
4. Length, slope of natural meanders 10
5. Schedule of data observed on meander channels .... 12
6. Meander characteristics 18
7. Depth-velocity characteristics of meander sections . . 25
8. Fish capture, summer 1971 28
9. Fish population estimates for Enman and Hazel
Marsh Meanders 29
10. Analysis of bed material 32
11. Analysis of suspended sediment and turbidity 33
-v-
LIST OF FIGURES
Fig. No. Page
1. Project location map A-l
2. Weaver Meander, aerial photo A-2
3. Hazel Marsh Meander, aerial photo A-3
4. Weaver Meander, construction plan A-4
5. Hazel Marsh Meander, construction plan A-5
6. Constructed channel cross-sections A- 6
7. Downstream No. 1 Meander, aerial photo A-7
8. Downstream No. 2 Meander, aerial photo A-8
9. Nelson Meander, aerial photo .... A-9
10. Enman Meander, aerial photo A-10
11. Stage-discharge rating curve A-ll
12. Plan, profile, cross-sections for Downstream
No. 1 Meander (Nl) A-12
13. Plan, profile, cross-sections for Downstream
No. 2 Meander (N2) A-13
14. Plan, profile, cross-sections for Nelson
Meander (N3) A-14
15. Plan, profile, cross-sections for Enman
Meander (N4) A-15
16. Plan, profile, cross-sections for Weaver
Meander (CI) A-16
17. Plan, profile, cross-sections for Hazel Marsh
Meander (C2) A-17
18. Topography of Hazel Marsh Meander, as built 11/69 . . A-18
19. Topography of Hazel Marsh Meander, existing 3/23/72 . A-19
20. Topography of Enman Meander, existing 3/25/72 .... A-20
21. Velocity distribution pattern, Hazel Marsh Meander . . A-21
22. Velocity distribution pattern, Enman Meander A-22
23. Transverse velocity distributions A-23
24. Size distribution of bed materials A-24
25. Point bar deposits, Hazel Marsh Meander A-25
26. Point bar deposits, Enman Meander A-26
27. Stream flow cross-overs, Enman Meander A-27
28. Rock jetty, Enman Meander A-28
29. Stream flow cross-overs, Hazel Marsh Meander A-29
30. Flow next to rip-rap, Hazel Marsh Meander A-30
-vi-
PRELIMINARY EVALUATION OF CHANNEL CHANGES
DESIGNED TO RESTORE FISH HABITAT
1. INTRODUCTION
Preliminary plans for the construction of 15 miles of Interstate Highway
1-90 west of Drummond called for channel changes which would shorten the
Clark Fork River by approximately 1800 ft. Based on the preliminary plans
and the authority of the Stream Preservation Law enacted by the Montana
Legislature in 1965, the Montana Fish and Game Commission recommended that
provisions be made for preserving the total length of the river in this
15-mile section of highway. The Montana Highway and the Fish and Game
Commissions mutually agreed that a workable solution would be to construct
two artificial meanders with combined lengths sufficient to recover the
1800 ft of stream length. The location of the project and its channel change
sections are shown in Fig. 1.— The two meanders, shown in Figs. 2 and 3 and
constructed at the locations indicated in Fig. 1, have approximate meander
lengths of 2600 ft. each and replace existing channel lengths of 1500 ft
each. The upstream meander (C2) is referred to as the Hazel Marsh Meander;
the downstream (CI), the Weaver Meander.
A summary of the channel changes in this section of highway given in
Table 1 includes original and new stream lengths, change in lengths and mean
values of old and new slopes (based on difference in channel bed elevations
at each end divided by stream length) . The excavation quantities required
for constructing the meanders are also given in Table 1.
The construction of the two meanders was completed in the fall of 1969.
The runoff in the spring of 1970 was the first high discharge passing through
these sections. Acknowledging the possibility of constructing similar meanders
for preserving the length of trout streams adjacent to future highway projects,
the Montana Highway Commission and the Federal Highway Administration requested
an evaluation of the artificial meanders. A study was initiated on December
1, 1970 to evaluate channel changes designed to restore fish habitat. The
1/ All figures are in Appendix A
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evaluation is based on (1) the hydraulic characteristics of the constructed
meander channels and (2) the acceptability of the constructed meander channels
as life-supporting habitat by species of fish found in the Clark Fork River
near Drummond. Studies of the hydraulic characteristics were conducted by
the Department of Civil Engineering and Engineering Mechanics of Montana State
University; the fish population studies by the Fisheries Division of Montana
Fish and Game Department in cooperation with the Bozeman Unit of the U. S.
Bureau of Sport Fisheries and Wildlife.
-3-
2. BASIS OF EVALUATION
The preliminary evaluation was made by comparing the hydraulic character-
istics and fish populations in existing natural meanders with those in the
constructed meanders.
The hydraulic character of river for fish habitat is determined by the
following factors: water surface slope, bed profile, velocity, thalweg (line
connecting the deepest points of the channel), and pool-riffle periodicity.
The ratio of the thalweg to the down valley distance is used as an index to
the susceptibility of a stream to provide fish habitat and is greater than
one for all streams. The greater this ratio, the more pools per 1000 ft of
stream length. The pool-riffle periodicity is given as the ratio of the
distance between riffles (shallow, fast-water sections) to the average stream
width.
Criteria for defining a meander are given by Leopold and Langbein (1966)
and Leopold, Wolman and Miller (1964) . The former report indicates meanders
are characterized by a ratio of meander length to average radius of curvature
in the bend of 4.7. The latter consider a stream segment to be considered
meandering if its sinuosity (ratio of channel length to down valley distance)
is greater than 1.5.
The studies of stream alterations on fish habitat and population reported
by Elser (1968) , Johnson (1964) , Swedberg (1965) , and Whitney and Bailey
(1959) give quantitative data on the reduction of fish population caused by
highway construction but do not present sufficient hydraulic data to determine
design criteria. Lewis (1969) indicates that cover (brush, overhanging
vegetation, undercut banks, and dead submerged portions of bank vegetation)
and velocity are the two most significant physical factors affecting variation
in trout populations in streams. Although optimum pool velocities were not
indicated, the velocities in the study range from 0.30 to 1.67 fps. Elser
(1968) also gives data on channel measurements from Little Prickly Pear
Creek in altered and unaltered sections indicating pool-riffle perodicities
ranging from 4 to 9 and ratios of the thalweg to down valley distance ranging
from 1.18 to 1.66 for unaltered sections. Leopold and Langbein (1966) indi-
cate the spacing of successive riffles is ordinarily from 5 to 7 times the
width.
-4-
The studies of Elser (1968), Johnson (1964) and Swedberg (1965) were
conducted on Little Prickly Pear Creek whose mean monthly discharges for
July, August and September, 1965, were 92, 52, and 86 cfs, respectively.
The mean discharges of the Clark Fork for the days observed in July,
August, and September, 1971, were 245, 267, and 520 cfs, respectively.
Because of the differences in the magnitudes of the average flows and the
average stream widths of the two streams, it was determined that the charac-
teristics of the constructed meander on the Clark Fork should be compared
with those of a natural meander of the same river.
The water surface slope, bed profile, average velocity, cross-sectional
area, samples of bed material and fish population data from natural meander
sections are compared with similar data taken in the constructed meanders.
The thalweg indicies, velocities, and pool-riffle frequencies found will
also be compared with those indicated in the literature cited above.
-5-
3. RIVER CHARACTERISTICS
3.1 Description of area
The Clark Fork River is formed by the confluence of Willow Creek and
Silver Bow Creek approximately 5 miles east of Anaconda. It flows northerly
for nearly 35 miles to Garrison then northwesterly for 25 miles through
Drummond where it turns and flows more westerly through the Garnet-Bearmouth
area. Flint Creek is the only perennial tributary with a significant flow
entering the Clark Fork in the portion studied; it flows into the Clark Fork
at Drummond, between the natural meanders upstream and the Hazel Marsh Meander.
Numerous intermittent tributaries feed the Clark Fork from both sides of the
valley .
Between its origin and Garrison the Clark Fork flows through a broad
lowland bordered by low terraces which slope gently upward to the mountains
on either side. At Garrison the river turns sharply to the northwest and
flows through a series of deep gorges interspersed with rolling uplands and
well-drained slopes. The present flood plain west of Drummond is made up
of alluvial deposits of sand and gravel.
The section of the Clark Fork River studied has an average gradient of
5 to 10 ft per mile and is limited in its lateral meandering by the slope of
the sides of the valley. These features classify it as a mountainous stream.
Valley streams are characterized by gradients less than 2 to 3 ft per mile
flowing in broad valleys allowing great latitude in the meandering.
The vegetation in the Clark Fork River Valley west of Drummond consists
of native bunch grasses, pine, fir, spruces, aspen, willow and alder. The
aspen, willow, and alder are predominant along the river banks.
3.2 River discharge records
Discharge records for the upper reaches of the Clark Fork River are
very meager. The only discharges of record consist of daily readings for
the months of April, May and June for 1968, 1969, 1970, and 1971 plus the
discharge measurements taken as part of the data for this study. The former
were taken for the U. S. Weather Bureau; the latter were taken monthly by
a local observer and also on days when hvdraulic and topographic field data
-6-
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were taken. The discharge data taken during the study period are given in
Table 2.
The discharge of the Clark Fork in the proximity of study section is
measured by a USGS wire-weight stage gage located at Drummond on the south
side of the bridge on U. S. Highway 10A and is downstream from the mouth of
Flint Creek. The maximum flow of record is 4450 cfs on June 2, 1969. The
minimum discharge recorded during 1971 was approximately 125 cfs.
The discharge record for Flint Creek consists of nine monthly observa-
tions above Willow Creek (not same creek previously mentioned) from October,
1971, through June, 1972, and three at the mouth of Flint Creek at Drummond;
these are given in Table 3.
Table 3. Flint Creek Discharge
Flint Creek Discharge, cfs
Date At Willow Creek At Drummond
10/13/71
137
11/14/71
127
12/14/71
114
1/12/72
93
2/15/72
90
3/14/72
188
4/13/72
172
218
5/15/72
432
419
6/13/72
377
317
The Willow Creek gaging station for Flint Creek is approximately five
miles above the junction of Flint Creek with the Clark Fork River and was
established in October, 1971 by the USGS. The Drummond gaging station for
Flint Creek was installed in April, 1972.
3.3 Constructed meanders
The plans for the Hazel Marsh and Weaver Meanders are shown in Figs. 4
and 5 respectively. The typical channel cross-section in the curved portions
-8-
of both meanders is shown at the top of Fig. 4 and in Fig. 6a with the deep
portion of the channel oriented to the outside of the curve. The field
notes for staking the construction indicate the cross-sections in the zone
of transition (where the deep portion of the channel crossed from one side
to the other) was as shown in Fig. 6b. The outside of the curves were armored
with type "BM rip-rap whose average piece was in excess of 0.5 cu yd with
some pieces as large as 3 to 4 cu yd. The armored areas are shown in Figs.
4 and 5.
The planimetric configurations of the constructed meanders were estab-
lished by locating old meander channels of the river in the areas selected
from aerial photographs. Gravel deposits and the patterns of vegetation
noted in the photographs and by field reconnaissance provided sufficient
evidence to relocate the old meander channels.
The hydraulic design criteria used for these meander channels was not
established in this study. Attempts to determine any formal design procedure
included a search of the field notes and the files in the Hydraulic Section
of the Montana Highway Department. From discussions with the engineers in
charge of laying out the meanders it was learned that the cross-sections in
the constructed channels were designed in the field with the following
provisions :
a. high-water stream width approximately equal to that in the natural
channels ,
b. maximum depth approximately equal to that in the natural channels,
c. deep flow area concentrated along outer bank of curve,
d. steep bank at outside of curve with gradual slope toward inside, and
e. constant slope along the centerline of channel.
The first four provisions were based on observations of sections of the
natural channel. The calculations for the channel hydraulics were not estab-
lished and design flow data were not available for this evaluation study.
As shown in Table 1, the Hazel Marsh Meander C2 is 2600 ft long with
a fall of 9.5 ft per mile. The original length of this reach was 1460 ft
and its fall was 17 ft per mile. The Weaver Meander CI is 2615 ft long
with a fall of 7.5 ft per mile. The original length of this reach was 1550
ft and its fall was 12 ft per mile.
3.4 Natural meanders
Four natural meanders initially were selected for study from aerial
photographs (scale 1:4800) of the Clark Fork River taken by the Montana
Highway Department on October 30, 1970. Tracings of the two constructed
meanders were superimposed on tracings of natural meanders to determine
which natural meanders were most geometrically similar to the constructed
ones. Two of the natural meanders selected were located downstream and
two upstream from the constructed meanders (see Fig. 1) . The natural
meanders are shown in Figs. 7, 8, 9, 10. The length and slope for each
are given in Table 4. The length listed is the total length of the control
section and extends beyond the individual meander curves.
Table 4. Length, slope of natural meanders
No. Name Length, Slope,
ft ft/mi
Nl D/S//1 2200 9
N2 D/S//2 2050 10.5
N3 Nelson 1600 7
N4 Enman 1550 7
-10-
4. EVALUATION METHODS
The methods used for the preliminary evaluation of the constructed
meanders required field observations and measurements for obtaining data on
the hydraulics and topographic characteristics and the fish population
estimates in both the natural and constructed meanders .
The hydraulic, topographic and fish population data obtained for each
meander are indicated in Table 5 along with their project reference names,
aerial photograph numbers, land ownership and legal land descriptions. The
designations I and II on water surface profiles and channel cross-sections
indicate that these data were obtained at two different times as discussed
in subsequent sections.
4.1 Hydraulics and topography
The principal hydraulic data observed were river discharge, water sur-
face profiles, and transverse velocity distributions. Isolated samples of
bed material, turbidity, and suspended sediment were obtained for comparison
purposes. The principal topographic data were channel cross-sections.
Transverse velocity distribution data were taken simultaneously with the
channel cross-sections. The river discharge measured by the stage recorder
at Drummond was recorded each day any observations were made. Attempts were
made to measure bed load transport rates at selected points in the river by
employing portable sediment traps designed in the laboratory. As these
devices proved unreliable and unmanageable, it was mutually agreed by the
principal investigator and the Montana Highway Research Engineer to forego
the observations of sediment transport rates.
The methods used for obtaining the above-listed data are discussed more
fully in the following paragraphs. The results of the hydraulic and topo-
graphic studies are presented graphically in Figs. 12 through 23 inclusive
found in Appendix A and discussed in Section 5.
4.1.1 Discharge measurements
The discharges occurring during the field measurements were obtained
from the readings of the stage gage at Drummond and the USGS stage-discharge
-11-
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rating curve shown in Fig. 11. The discharges for meanders Nl, N2, CI and
C2 were assumed to be equal to those at the gaging station. The discharges
for meanders N3 and N4 (Nelson and Enman, respectively) were found by sub-
tracting the flows estimated for Flint Creek using Table 2 from the discharge
at the gaging station on the Clark Fork at Drummond.
The short period of discharge records for both the Clark Fork River and
Flint Creek, the infrequent observations of data, and the fact that the
existing data show that no observations of all three gaging stations were
taken on the same day prior to April, 1972, make any estimate of the flow
contributed by Flint Creek during the study period purely an estimate.
The flow of Flint Creek is estimated to contribute from 18 to 31 percent
of the discharge in the Clark Fork below Drummond. The discharge observed
for the meanders below Drummond (CI, C2, Nl, N2) and estimated for those
upstream (N3, N4) from the gaging station are indicated in Figs. 12 through
17 and discussed in Section 5.
4.1.2 Water surface profiles
The first set of water surface profiles (labelled I in Table 5) were
taken on all six meanders in late June and early July, 1971, as soon as
practicable after the high water period, to determine if the natural meanders
selected were similar to the constructed ones in (1) overall slope and
(2) general pool-riffle frequency.
Points marking the flow lines of the meander channels were established
by a stadia traverse run on both sides of river. A level circuit was run
to determine the water surface elevations adjacent to these flow line points
for plotting the water surface profiles. After reviewing the first set of
water surface profiles further field work was carried out on the two con-
structed (CI and C2) , and one upstream (the Nelson, N3) and one downstream
(the Downstream No. 1, Nl) natural meanders.
The second set of water surface profiles (II, Table 5) were taken on the
two constructed meanders and the Nelson and Downstream No. 1 natural meanders
in late August, 1971, during the low water period of the river.
Water surface profiles were also obtained from cross-section data taken
on the Enman and Hazel Marsh meanders in March, 1972.
-13-
The planimetric views of the meander studied and their water surface
profiles are shown in Figs. 12, 13, 14, 15, 16, and 17 and discussed in
Section 5.1.
4.1.3 Channel cross-sections
The first set of channel cross-sections (I, Table 5) were taken on the
two constructed (Cl, C2) and the Nelson (N3) and Downstream No. 1 (Nl) natural
meanders in late August, 1971, at the locations shown in Figs. 12, 14, 17
and 18 to determine if the cross-sections at selected points in the constructed
channels were similar to those at the same relative locations in the natural
meanders. The distance between these transects varied from 250 to 500 ft
apart measured along the center of the flow line. Velocity distribution
data were recorded at five or more points on each cross-section.
Cross-section data were obtained by the generally accepted methods using
a level, a rod and a tape (or a transit for stadia measurements) . Velocity
distribution data were obtained by using a No. 622-F Gurley current meter
to record flow velocities at three or more points on each vertical of five
or more points on the transects.
A review of the channel cross-section along with the data available
from the initial fish population samples indicated the cross-sections were
too far apart along the length of the stream to give meaningful bed profile
data. It was mutually agreed among the Montana Highway Department Research
Engineer, the Fish and Game Fish Habitat Leader and the principal investigator
to obtain more intensive data on one of the constructed and one of the natural
meanders. The Hazel March (C2) and Enman (N4) Meanders were selected as
the constructed and natural channel sections, respectively, for intensive study
based on discussions among Dr. Richard Graham of the Bureau of Sport Fisheries
and Wildlife, Mr. Ron Marcoux of the Fisheries Division of the Montana Fish
and Game Department and the principal investigator.
The second set of channel cross-sections (II, Table 5) were taken in
late March, 1972, at the locations approximately 100 ft apart on the Enman
and Hazel Marsh Meanders. The Enman Meander section used in the March
survey was approximately 1000 ft longer than originally used for the first
set of water surface profiles to give a larger sampling area for the fish
population data.
-14-
The results of the hydraulic and topographic surveys are shown in
Appendix A in Figs. 12 through 23, inclusive.
4.1.4 Bed material samples
Samples of bed material were obtained at selected points shown in Figs.
14, 16, and 17 from the two constructed meanders and one natural meander
(Nelson) in October, 1971, at same relative locations in the meanders and
stream-flow patterns. These were taken to determine if the gradation of
the sand and gravel in the constructed meanders is similar to that found in
the same relative positions in natural meanders. These initial samples,
obtained in periods of low water, were taken on the banks and bars adjacent
to the flow sections. A shovel and plastic-lined bags were used to collect
the individual 15-lb samples.
Additional samples were taken during the more intensive studies of the
Enman (N4) and Hazel Marsh (CI) Meanders in April at the points shown in
Figs. 19 and 20. A specially constructed sampler made from a 3-in-dia
steel pipe 6 ft long was used to obtain bed samples out in the stream.
4.1.5 Water turbidity and suspended sediment samples
Water samples for comparing the turbidity levels of the stream flow in
the natural meanders with those in the constructed meanders were taken at one
or two points on each of three transects in the two constructed and one
natural (Nelson) meanders shown in Figs. 14, 16 and 17 in late October, 1971.
Water from two 1000-ml pothyethylene bottles filled with depth- integrated
samples at each point were analyzed using a Hach Model 2100 turbidimeter
within fifteen minutes from time of sampling in accordance with the nephelo-
metric technique described in Par. 163A, Standard Methods (1971).
Suspended sediment samples were taken during the same observation period
at points on the same transects used for turbidity samples. Generally three
depth- integrated samples were taken in 1000-ml polyethylene bottles at each
sampling point. The quantities of suspended sediment were determined by
filtration and evaporation techniques adapted from Section 224, Standard
Methods .
-15-
4.2 Fish population survey
Fish populations were sampled from a boat with the aid of a variable
voltage D-C electrof ishing shocker. A mark and recapture method of Peterson
(described by Ricker, 1958) utilizing two or more marking survey runs in
each designated meander followed in approximately one week by one or more
recapture runs was the basis for all estimates. Fish captured during marking
runs were measured, weighed, marked with distinctive fin clips and released
near the point of capture. Trout estimates were for yearlings and older fish
during the summer and fall sampling periods and for fish two years old and older
during the spring sampling. The separation into age groups was made using
the length frequency distribution. Sampling for trout in the younger age
groups was very inefficient. Population estimates were limited to whitefish
longer than 7 inches.
Initial sampling was done on the upper natural meanders (N3, N4) and the
constructed meanders (CI, C2) in late August and early September, 1971. In
addition, a survey run was made on 14,000 feet of the unaltered river above
the constructed meanders in a reach including the Nelson (N3) and Enman (N4)
Meanders to obtain an estimate of the average population density.
Too few fish were captured in the 1971 survey runs in all study sections
except the Hazel Marsh meander to make valid population estimates. It was
mutually agreed to confine and intensify additional sampling to the Hazel
Marsh Meander (C2) and the Enman Meander (N4) with an increased length.
These sections were sampled in March and August, 1972.
Pronounced riffle areas were used to delineate the boundaries of sampling
sections so that fish movement would be minimized. This resulted in fish
sampling sections that were somewhat longer than those used to obtain hydrau-
lic and topographic data.
-16-
5. PRESENTATION AND DISCUSSION OF RESULTS
The results of the hydraulic, topographic and fish population data obtained
for a preliminary evaluation of the constructed meanders are presented and
discussed in the following. Results appearing in tabular form are located
in this section; results summarized graphically are found in Figs. 12 through
23 in Appendix A.
5.1 Hydraulic and topography
The hydraulic and topographic field data have been reduced to a series
of drawings shown in Figs. 12 through 23 giving the planimetric view, water
surface profiles, flow cross-sections, topography and velocity distributions
of the study sections .
Figures 12 through 17 show the planimetric configuration of the stream,
the profiles of the water surfaces and channel profiles, and typical channel
cross-sections. The planimetric views contain stationing marks 200 ft on
center and indicate the location where channel cross-section data were taken.
The profile views show the water surface profiles obtained from level circuits
and channel profiles of the thalweg obtained from cross-section data. Points
along the stream where channel cross-section were taken are indicated on the
profile view. The channel cross-sections presented are shown as viewed look-
ing downstream when located at the channel section. Information obtained
from scaled-up drawings similar to Figs. 12 through 17 for comparing the
planimetric properties of the sections including stream length, average
width, down valley distance, average radius of curvature, ratio of meander
length to average curve radius, and sinuosity are summarized in part (a)
of Table 6. The average radii of curvature were determined graphically
by constructing bisectors to chord lengths connecting adjacent points along
the stream centerline. The radii to different points along the stream centerlines
were scaled from the approximate locus of the intersections of the chord
bisectors. The down valley distance is the chord distance across the principal
curve of the meander between the principal inflection points. Values used
were scaled from the planimetric views.
-17-
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The hydraulic characteristics of the meanders including discharge,
average slope of water surface, pool-riffle frequency, maximum average
velocity, minimum average velocity, and mean average velocity are summarized
in part (b) of Table 6. The profiles were plotted to a scale greater than
shown in Figs. 12 through 17 for analysis. The pool-riffle frequency was
determined by dividing the distances from the beginning of one pool to the
beginning of the next by the average stream width throughout that reach.
The pools were judged to occur in regions of the stream having a flat profile.
The average velocity values shown in columns 13, 14, 15, of Table 6
were obtained by dividing the discharges by the flow areas of the cross-
sections given in Figs. 12 through 17; the water surface was placed on the
respective sections according to its elevation on the date given in column
9. The discharges indicated for the Nelson meander (N3) are the same as
those occurring downstream from Drummond as the records of the Flint Creek
flow were not begun until October, 1971.
The velocity ranges shown are based only on values obtained at seven
cross-sections in each meander except for those given for N4 on 3/24/72 and
for C2 on 3/22/72. The velocity values for the March, 1972 discharges are
based on 26 cross-sections in each meander section.
5.1.1 Quantitative characteristics
The quantitative data summarized in Table 6 show the following:
a. With the exception of Nl, the planimetric parameters (meander
ratio, Lc/R; sinuosity, Lc/D; radius-width ratio, R/W) indicate all the
meanders selected for tentative study have similar geometric characteri-
stics. The compound curve feature of Nl created two distinct radii of
curvature. These did not allow a single average radius of curvature to
typify this curve. Based on the radius-to-width ratio, meanders N3 and
CI should be compared as one set and meanders N4 and C2 as another.
b. The slopes of the water surfaces indicate that the meanders Nl
and N2 are significantly steeper for all ranges of flow than are those of
N3, N4, CI and C2. For flows greater than 1000 cfs, N4, Cl, and C2 have
slopes ranging f^om 7.1 to 7.8 ft per mile; for flows less than 350 cfs,
the slopes of N3, Cl and C2 range from 5.6 to 6.8 ft per mile.
-19-
c. The range of average velocities for N2, N4, CI and C2 indicates the
channels have approximately the same degree of non-uniformity for higher
flows. Non-uniformity reflects the changes in stream cross-sections along
the flowline of the river. The variation between the maximum average velocity
and the minimum average velocity for the constructed sections CI and C2 are
nearly the same as indicated for the natural sections.
d. The pool-riffle frequencies indicated from the water surface profiles
and calculated for Table 6 correspond to the ranges observed by Elser (1968) .
A definite pool-riffle formation could not be detected in the water surface
profile of the Weaver Meander (CI) . This may be attributed to the fact that
the artificial meanders were constructed on a constant grade throughout their
reaches .
5.1.2 Qualitative characteristics
The qualitative data summarized in Figs. 12 through 17 show the following:
a. The cross-sections show the flow area of the stream approaching
the meander is well-distributed over the width of the channel. As the flow
enters the curved portion of the channel, the flow area deepens, narrows
and shifts to the outside of the curve. It was noted for 4 of the 5 sections
where discharge and cross-section data were obtained that the minimum average
velocities occurred in the deep, narrow sections although the maximum local
point velocities also occurred in these regions.
b. The effect of the small islands on the water surface profile of
the Downstream Meander No. 2 (N2) precluded any further investigations of
this reach. This was not unexpected; the water surface profiles were taken
to document this type of stream configuration.
The lateral bar formations in the Downstream Meander No. 1 (Nl) appeared
during the low water period in August, 1971. Although bars similar to those
were not expected to be formed yet in the constructed meander sections, cross-
section data were taken for future reference on this or similar projects.
c. In general, the shape of the flow cross-sections in the constructed
meanders (CI, C2) shown in Figs. 16 and 17 are similar to those found at the
comparable stream locations in the natural meander sections (N3, N4) shown
in Figs. 14 and 15.
-20-
d. The design of the constructed channels in the principal section of
the meander curves (sections 2, 3, 4 and 5 in Fig. 16 and sections 2, 3, 4
and 5 in Fig. 17) appears to be a stable configuration for those particular
channels. The design of the channels in the upstream and downstream reaches
of the meanders where the current and main flow crosses from one side of
the stream to the other did not conform to the design channel configuration.
This is noted in sections 1, 6 and 7 of Fig. 16 and to a lesser degree in
sections 1, 6 and 7 in Fig. 17. The cross-over sections occur over longer
lengths than provided in the design and at locations 50 to 100 ft downstream
from the inflection point of the compound channel curve.
e. The thalweg profiles are highly irregular and that of the constructed
meander (C2, Fig. 17) does not bear a strong resemblance to the thalweg of
the natural meander (N4, Fig. 15) yet. The thalweg of the constructed meanders
may tend toward those of natural channels with time. The dashed line repre-
senting the thalweg profiles in Figs. 12, 14, 16, 17 were plotted from the
data of the cross-sections spaced 250 to 500 ft. This proved to be insuffi-
cient to represent the bed profile accurately as shown by the thalweg data
points plotted as circles in Fig. 17. The latter data and the thalweg profile
shown in Fig. 15 were taken from the intensive study of the Hazel Marsh
Meander (C2) and the Enman Meander (N4) . A close examination of the thalweg
data of Fig. 17 indicates that some scour has taken place between August 26,
1971, and March 22, 1972.
5.1.3 Results of intensive studies
More detailed field studies were conducted on one natural meander and
one constructed meander to obtain more complete hydraulic, topographic and
fish population data. Based on the quantitative and qualitative results of
the preceding sections and the considerations of accessibility for the fish
sampling data, the more intensive studies were conducted on the Enman Meander
(N4) and the Hazel Marsh Meander (C2) . Channel cross-sections and velocity
distribution measurements were taken at intervals of approximately 100 ft
of stream length. The discharges were 1225 cfs in C2 and 995 cfs in N4 .
The typical channel cross-sections and stream profile data are shown in
Fig. 15 and 17 for the Enman and the Hazel Marsh Meanders, respectively.
-21-
Topographic maps of the channel beds based on data from the intensive
studies are shown in Fig. 19 and 20 for C2 and N4, respectively. The topography
of the Hazel Marsh Meander (C2) as constructed is shown in Fig. 18.
Maps with lines of constant velocity are shown in Figs. 21 and 22. The
transverse velocitv distributions at selected cross-sections of CI and N4 are
shown in Fig. 23.
5.1.3.1 Channel topography
(A) A comparison of the channel topography of C2 observed in March 1972
(Fig. 19) with constructed contours (Fig. 18) shows:
a. A riffle area is forming on the inside of the curve in the
region of the upstream crossover between stations 18+00 and 20+00.
b. Localized scour is creating deep holes in two areas (between
stations 15+00 and 17+00 and between 7+00 and 10+00) along the
outside of the primary meander curve.
c. The deposition of material downstream from station 3+00 is
filling in the central section of the channel and restructuring the
pool along the outside of the curve in the vicinity of stations
2+00 and 5+00.
(B) A comparison of the channel topography of C2 (Fig. 19) with that of
N4 (Fig. 20) shows the bed of the constructed meander is tending toward the
configuration of the natural meander. The following points illustrate this
tendency:
a. The pool forming between stations 20+00 and 24+00 on the
upstream end of the constructed meander (C2, Fig. 19) corresponds
to the pool found between sections 24 and 26 of the natural meander
(N4, Fig. 20) .
b. The riffle forming between stations 18+00 and 20+00 of C2
corresponds to the broad riffle located between sections 21 and 24
of N4.
c. The pool forming between stations 15+00 and 17+00 of C2
corresponds to the pool located between sections 20 and 21 of N4 .
d. The pool forming between stations 7+00 and 10+00 of C2
is similar to that between sections 16 and 18 of N4 .
-22-
e. The restructured topography between station 2+00 and 5+00
of C2 is similar to that between sections 11 and 14 of N4.
5.1.3.2 Channel hydraulics
(A) A comparison of the velocity distribution patterns observed in the
constructed meander C2 (Fig. 21) with those in. the natural meander N4 (Fig.
22) shows:
a. Two areas of velocity in excess of 5 ft per sec (fps) between
stations 20+00 and 24+00 in the inflow section of C2 correspond to the
single area with a velocity greater than 5 fps between sections 24 and
26 of N4.
b. The second zone of velocity in excess of 5 fps in C2 is
located further downstream and around the curve from the comparable
high-velocity zone in N4. The difference in the relative locations
is caused by the difference in channel topography of this portion
of the respective meanders: the bed profile of the constructed
meander C2 (Fig. 17b) has less slope between station 16+00 and 18+00
than the slope of the natural meander N4 (Fig. 15b) between sections
20 and 23. Also the curvature of the channel for C2 in this reach
is greater than that for N4.
c. The two small zones of velocity greater than 5 fps between
stations 7+00 and 9+00 of C2 correspond to those at section 16 and
between sections 12 and 14 of N4.
d. The region of velocity in excess of 4 fps extends from
station 5+00 to station 21+00 throughout the primary curve of the
constructed meander C2. Two separate regions of velocity in excess
of 4 fps exist in the primary curve of the natural meander N4. This
indicates a somewhat more pronounced pool-riffle tendency in the
natural meander.
(B) The transverse velocity distributions at seven cross-sections
situated at similar locations on the constructed (C2) and natural (N4)
meanders are shown in Fig. 23. The velocities used were obtained at six
tenths of the depth (0.6D) at each of the points indicated on the cross-
sections. The locations of the cross-section in the meanders are shown in
Figs. 15 and 17. The data were taken March 22-23, 1972 when the discharges
-23-
were 1225 cfs and 995 cfs in C2 and N4, respectively. Noting that the Hazel
Marsh Meander (C2) curves to the right and the Enman Meander (N4) to the left,
Fig. 23 shows the transverse velocity distribution patterns for cross-sections
at comparable stream locations in the two sections to be similar:
a. The point of maximum velocity is shifted toward the
bank on the inside of the meanders in the inflow sections (C2,
sec. 1,2; N4, sec. 22,24).
b. The point of maximum velocity is shifted toward the
outside of the meanders in the central sections of the principal
curve (C2, sec. 4,5,6; N4, sec. 16,17.2,18,20).
c. The point of maximum velocity is again shifted toward
the inside of the meander in the outflow sections (C2, sec. 7;
N4 , sec. 14) .
(C) The depth-velocity characteristics of the constructed (C2) and
natural (N4) meander sections are summarized in Table 7 for the data obtained
March 22-23, 1972. Data for C2 is found in Table 7a; for N4, in Table 7b.
The flow areas (cols. 2 and 9) were obtained by plotting the cross-sections
and planimetering the areas. The average depths of flow (cols. 4 and 11)
are the flow areas divided by the surface widths. The similarities between
the ratios of maximum depth to average depth and maximum velocity to average
velocity for comparable sections in the respective meanders may be determined
from Table 7. An indication of the similarities of the meanders based on
the maximum, minimum and averages of these ratios for the respective meanders
is shown in the following chart :
Hazel Marsh (C2) Enman (N4)
Max. d /d 1.97 1.90
m
Min. d /d 1.01 1.09
m
Ave. d /d 1.53 1.55
m
Max. V /V 1.59 1.57
m
Min. V /V 1.11 1.01
m
Ave. V /V 1.35 1.33
m
-24-
Table 7. Depth -velocity characteristics of meander sections
Flow
Surface
Ave .
Max.
Ave .
Max
Station
area ,
width ,
depth ,
depth ,
velocity,
veloc
ft2
ft
ft
ft
f ps
f ps
A
B
d
dm
V
V
vm
/ 1 \
(1)
(2)
(3)
(4)
(5)
(6;
7a. Hazel
Marsh
Meander (C2)
1+00
r\ r~ r~
255
-1 1 A
118
A 1
2.1
O A
3.0
4.8
0 . 0
2+00
316
122
2.6
3.0
O A
3 . 9
/. a
4.9
O i AA
3+00
/ A f
405
108
3.8
/* A
6.0
O A
3.0
4.3
4+00
346
109
3.2
5.5
3 . 6
3 . 3
C I Art
5+00
360
1 ^ A
110
3.3
/ A
4.0
3 . 4
c a
5 . 0
f • AA
6+00
312
106
O A
3.9
C A
5.0
3.8
4.5
7+00
0 0 c
335
1 A 1
101
3.2
6.0
O "7
3 . 7
C A
5 . 0
o+OO
O O "7
337
'111
111
O A
3.0
C A
5.0
3 . 6
4 . /
Aj_AA
9+00
285
1 A "7
107
0 0
3.8
r a
5.0
4 . 3
C A
5 . 0
1 n 1 c\r\
10+00
286
A A
99
A A
2.9
C A
5.0
4 . 3
4 . 6
1 1 ) A A
11+00
315
1 A C
105
O A
3.0
C A
5.0
O A
3.9
4 . 9
12+00
330
1 1 T
112
2.9
a a
6.0
O "7
3 . /
c a
5 . 0
13+00
343
1 in
110
O A
j»0
C A
5.0
3 . 6
C A
5 . U
14+00
OCT
251
112
A A
2.2
C A
5.0
/ a
4.9
6 . 1
1 c 1 nn
15+00
2/1
A C
95
2.8
r~ a
5.0
4 . 5
5.5
16+00
368
O A
80
4.6
6.0
3.3
/ "7
4 . 7
1 "7 1 AA
17+00
346
A 1
91
O A
3.8
5.0
3 . 7
/ -7
4 . 7
18+00
438
104
4.2
5.0
2.8
4.3
1 A 1 Art
19+00
1 A 1
381
112
3.4
5.0
3.2
4.3
20+00
346
106
3.3
3.0
3.5
5.6
21+00
345
91
3.8
7.0
3.5
5.4
22+00
262
91
3.0
5.0
4.5
NG
23+00
306
101
3.0
5.0
4.0
5.6
24+00
345
109
3.2
4.0
3.6
5.6
25+00
332
119
2.8
5.0
3.7
4.5
25+96
492
140
2.5
6.0
2.5
3.9
NG - Error in
observation of
maximum
velocity
-25-
(Table 7 - Cont'd)
Section
(8)
Flow
area,
ft2
A
(9)
Surface
width,
ft
B
(10)
Ave.
depth,
ft
d
(11)
Max .
depth,
ft
dm
(12)
A _
Ave.
velocity,
fps
TT
V
(13)
if
Max .
velocity,
fps
TT
vm
(14)
7b . Enman
Meander
(N4)
6
293
97
3.0
3.0
3.4
5.1
7
210
99
2.1
3.0
4.7
6.9
8
240
70
3.0
4.0
4.2
6.1
9
209
129
1.6
3.0
4.8
5.7
10
219
123
1.8
2.0
4.6
5.3
11
258
90
2.8
4.0
3.9
3.9
12
235
92
2.6
4.0
4.2
5.8
13
236
80
3.0
5.0
4.2
5.7
14
252
128
2.0
2.0
4.0
5.8
15
261
126
2.1
4.0
3.8
4.5
16
230
92
2.4
4.0
4.3
5.2
17
276
79
3.5
6.0
3.6
4.0
17.1
353
96
3.6
6.0
2.9
3.9
17.2
243
77
3.3
5.0
4.1
4.7
18
345
99
3.5
6.0
2.9
4.6
19
243
88
2.8
5.0
4.1
5.1
20
214
92
2.3
3.0
4.7
4.3
21
"307
j . j
J • X
H . J
22
310
136
2.3
3.0
3.2
5.8
23
310
164
1.9
3.0
2.3
6.1
24
218
86
2.4
4.0
4.6
5.3
25
206
78
2.6
4.0
4.8
5.4
26
181
87
2.1
4.0
5.5
NG
-26-
5.2 Fish population estimates
The data for sampling the fish population in the meanders studied are
presented in Tables 8 and 9. The number of fish captured in the preliminary
survey runs of 1971 are shown in Table 8. The estimates of the fish popula-
tion in the Hazel Marsh (C2) and Enman (N4) Meanders given in Table 9 were
calculated using the Chapman modification of the Petersen estimator (equation
3.5, Ricker, 1958).
The most common fish collected in order of decreasing abundance were
mountain whitefish, brown trout and largescale sucker. Others collected in
much smaller numbers included longnose sucker, northern squawfish and rainbow
trout. Although suckers (combined species) were collected about as frequently
as brown trout, the recapture rates were so low that population estimates were
not possible.
The only population estimates that could be made for the summer, 1971
sampling were for brown trout and whitefish in the Hazel Marsh Meander (C2)
and brown trout in the control survey. Estimated number and weight per 1,000
feet of stream for brown trout in the control survey were 40 (+ 16) and 37
(+ 15) pounds, respectively. The 1971 summary of fish sampling (Table 8)
shows low recapture rates in the Nelson (N3) , Enman (N4) and Weaver (CI)
meanders. These low or non-existant recapture rates do not permit valid
population projections to be made. The data also show:
a. more fish of all species were captured in the Hazel
Marsh Meander (C2) than in the Weaver Meander (CI), and
b. more fish per 1000 feet of stream were captured in the
Hazel Marsh meander (C2) than in the Nelson Meander (N3) , the
Enman Meander (N4) or the 14,000 ft control survey section.
These results may only reflect a greater efficiency in the sampling rather
than a greater fish population per 1000 ft in the Hazel Marsh Meander.
The population estimates for both brown trout and whitefish based on the
intensified studies in the Hazel Marsh (C2) and Enman (N4) Meanders given in
Table 9 are of limited accuracy as is shown by the large confidence intervals.
Considering the variations between sampling periods and the large overlap of
confidence intervals tb^re was no significant difference in numbers and
pounds of fish per 1000 ft of stream length between the constructed (C2) and
natural (N4) meanders. Also the population estimates of brown trout for the
-27-
Table 8. Fish captured during summer, 1971
Numbers Captured
Brown Trout Whitefish Suckers Squawfish
Nelson - N3 (1,650 ft)
Marking Runs (2) 15 16 2 0
Recapture Run (1) 2 (0)* 26 (0) 11 (1) 0
Enman - N4 (1,550 ft)
Marking Runs (2) 14 27 22 0
Recapture Run (1) 18 (2) 27 (0) 7 (0) 1 (0)
Weaver - CI (2,615 ft)
Marking Run (1) 2 32 8 1
Recapture Run (1) 0 (0) 13 (0) 7 (0) 0 (0)
Hazel Marsh - C2 (2,600 ft)
Marking Runs (2) 50 86 65 3
Recapture Run (1) ' 24 (11) 95 (8) 26 (2) 3 (0)
Control Survey (14,000 ft)
Marking Runs (2) 146 177 118 2
Recapture Run (1) 68 (17) 257 (4) 53 (6) 1 (0)
^Numbers in parentheses = recaptures
-28-
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two study meanders (C2,N4) were not significantly different from that found
in the control survey of 14,000 ft of stream. The average lengths of brown
trout and whitefish in the constructed meander were not significantly different
from those in the control meander.
Attempts to samole the fish population in the Weaver Meander (C2) were
also made in March and August, 1972. The number of fish captured on both
dates was too low to allow any population estimates to be made. The popula-
tion in this meander may be relatively high and comparable to that in the
Hazel Marsh Meander but the combination of deep and fast water along the
outside of the curve made it difficult to control the boat containing the
shocker. The lack of control did not permit adequate probing for fish in
the deep, fast water areas and made the capture of fish difficult.
5.3 Bed materials
The results of the sieve analyses of 14 samples of bed materials obtained
from selected locations in the meanders studied are presented in Table 10.
The sieve sizes given are for U. S. Standard sieves; d^ is the median grain
size (50 percent larger and 50 percent smaller) . The general size distribu-
tion is shown by the fractions of cobbles, coarse aggregates, coarse sand, fine
sand and silt in each sample.
The results summarized in Table 10, indicating the size of bed materials
range from +2 inches down to 200 mesh, do not present an accurate distribution
as a higher percent of larger cobbles are found in areas of both the con-
structed and natural meanders. The devices and techniques employed for
obtaining samples restricted the gradation to be similar to the material shown
in Fig. 24a found on the point bar forming at station 15+00 in the Hazel Marsh
Meander (C2) . Fig. 24b shows a representative sample of the material found
at the upstream end (station 17+00) of the same bar. Figs. 25a and 25b
illustrate the natural gradation of material along the bar formed on the inside
bank of a meander channel. Fig. 25a shows the larger cobbles deposited at
the upstream end of the bar where Figs. 24a and 24b were photographed. Fig.
25b shows the fine sands deposited at the downstream end of the same bar.
Similar size gradations are noted in the photographs of point bar formations
in the Enman Meander (N4) in Figs. 26a ard 26b. Fig. 26a is at section 18
and 26b at section 14 on N4.
-30-
The data for the four samples obtained at different points across the
stream at section 23 of the Enman Meander (N4) indicate the variability of
material througout a given cross-section.
The foregoing remarks indicate that isolated bed samples yield only
limited information and should be supported by other field observations.
The data of Table 10 and field observations indicate the material in the
two constructed meanders to be slightly coarser than that in the natural
meanders. This may be attributed to the existence of local gravel deposits
uncovered in the area of the constructed meanders. Also the duration of flow
through these new channels has not been sufficient to deposit any appreciable
amount of fine sand into the slow water areas of the meanders.
The data also indicate that there is very little silt in the total reach
of the river studied.
5.4 Suspended sediment and turbidity
The results of the analyses for turbidity and suspended sediment of water
samples from the two constructed (Cl,C2) and one natural (N3) meanders are
given in Table 11. The location of the cross-sections indicated in column 1
are referred to Figs. 14, 16 and 17. The R or L designations indicated dis-
tances from the right or left bank at the edge of the water when facing upstream.
The suspended sediment shown is the average of two or three samples taken at
each point on the cross-section and is given in parts per million (ppm) . The
measure of turbidity is given in Jackson turbidity units (JTU) as described
in Par. 163 of the Standard Methods (1971). A JTU index of 5 or less is
suitable for domestic water supplies without clarifying.
The results given in Table 11 show:
a. The amount of suspended sediment varies with location in
the cross-section and location of the cross-section in the meander.
b. The amount of suspended sediment in the constructed meanders
is nearly the same as that indicated in the natural meander at this
time of the year.
c. The level of turbidity in the constructed meanders is the
same as in the natural meander.
The suspended sediment and turbidity samples were taken during a period
of relatively low water to have an indication of conditions more typical of
-31-
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-32-
Table 11. Analysis of suspended sediment and turbidity
Cross-section
Point Distance
Suspended
sediment ,
Turbidity
units ,
Temp-
erature
ft
ppm
JTU
°F
(1)
(2)
(3)
(4)
(5)
Weaver (CI)
200' U/S from sec. 1
1
36
It
bk
15
3.9
2
76
18
3.2
45
3
106
40
Sec. 5
1
38
It
bk
30
2
46
40
3.4
45
3
bU
c/.
200' D/S from sec. 7
1
36
It
bk
18
—
2
52
36
3.1
45
3
"7 -7
77
1 c
16
Hazel Marsh (C2)
24+50
1
20
It
bk
29
4.3
2
60
29
4.2
39
3
80
19
11+50
1
20
It
bk
21
2
45
It
bk
21
4.1
40
6+00
1
35
It
bk
22
2
50
35
4.4
45
3
85
14
4.8
Nelson (N3)
Sec. 4
1
35
rt
bk
33
2
60
20
3.8
43
3
80
31
3.9
River discharge at Drummond , 645 cfs
-33-
the fishing season and spawning periods. The period of maximum amounts of
suspended sediment and turbidity occurs annually during the spring runoff
but is of a temporary nature. High levels of suspended sediments in low
water periods are more indicative of conditions adverse to fish than those
occurring in the runoff periods.
The results of these analyses indicate the construction of the meanders
has not uncovered or created any permanent sources of suspended sediment or
turbidity-producing material.
5.5 Other conditions observed
A major consideration in the design of fish habitat concerns the cover
available along the banks of streams and the resting areas to be found in long
runs of swift water. In natural meanders the vegetative growth along the
stream often provides both. Examples of this are given in Figs. 27a and 27b
showing fast water sections along the bank in the Enman Meander (N4) .
Fig. 27a shows the flow (toward the bottom of the picture) sweeping
around the point bar with the swift water section crossing to the outside of
the bend. The root structure and occasional fallen tree trunks protruding
into the fast flow create small local zones of relatively slow water along the
bank where the trout may rest and find cover. The foliage also provides shade
for cover in the summer.
Fig. 27b (with flow toward the bottom again) shows a condition similar to
that of Fig. 27a with the riffle at the cross-over in the upper right corner
of the picture more pronounced. The important feature of Fig. 27a is that
although the main channel is essentially a tangent from the lower left to
the upper right of the picture, the flow has come around the curve on the
right side of the stream and continues to curve around back to the left side
of the stream. The vegetation on the left side then provides the cover and
resting spots in the swift water. This view is looking upstream from section
6 in the Enman Meander (N4) . Trout were generally captured on the outside of
bends where zones of relatively deep and fast water were interrupted by root
structures or protruding vegetation.
A larger resting pool in a swift water zone is provided by the backwater
area downstream from the rock jetty in Fig. 28. The observer is facing
-34-
upstream; the jetty is shown at section 21 of the Enman Meander (Fig. 20) .
Althought the tip of the jetty does not extend out into the zone of maximum
velocity (Fig. 22), it does create a scour hole downstream from it. Residents
of the area related that two other similar jetties were constructed downstream;
one between section 18 and 19 and the other between 18 and 17.5(1). As no
evidence of either of these could be located, it was conjectured that the tips
of the jetties extended into the swift water (which is nearer bank in this
region) and were eroded. Apparently the rock fragments used in the construction
of these jetties was not large enough to withstand the high velocities accom-
panying the spring runoff flows.
The swift water zones in the constructed meanders occur along the rip-
rapped banks as shown in the photographs of the Hazel Marsh Meander (C2) in
Figs. 29a and 29b. Looking upstream from station 19+00 Fig. 29a shows the
high velocity flow separating from the rip-rap section on the left and
starting the cross-over. It is to be noted that a well-defined riffle has
not yet formed in this cross-over region. Fig. 29b shows the same cross-over
as viewed looking downstream from station 22+00.
The large individual pieces of rip-rap along the edge of the high
velocity zone create local backwater and slow water pools along the bank.
Trout were often captured around or behind these large boulders, particularly
during the high water of the March 1972 sampling period. Two good examples of
this are the two boulders noted midway on the left side of Fig. 29a and just
above the midpoint on the right side of Fig. 29b. The flow conditions in the
vicinity of these two rocks are shown in Figs. 30a and 30b. The quiescent
area between the two rocks (Fig. 30a) affords a deep pool as a rest area. The
white water zone just off the tip of one of these pieces of rip-rap (Fig. 30b)
provides a certain amount of cover for the rest area behind the rock.
The relatively steep banks and the random placement of the large indivi-
dual pieces in the rip-rap sections provide bank stability and create a
diversity of habitat for trout and other aquatic life. Uniform placement of
smaller rock on flatter backslopes (2:1) will provide bank stability and a
more efficient hydraulic section but will not provide as suitable habitat for
trout and whitefish.
If the individual rip-rap pieces were much smaller than those placed in
the constructed sections, the high velocities of the spring runoff would wash
-35-
them out over a relatively short period of years. According to the residents
in the vicinity, the outer bank of the Enman Meander (N4) was rip-rapped with
hand-lain rock between sections 18 and 21 (Fig. 20). The maximum size of the
individual pieces was approximately 18 x 18 x 10 inches; most were smaller.
The residents claim this rip-rap was installed 5 or 6 years prior to this
study (1972). A few scattered pieces and one section 20 ft long were the only
remnants found. Apparently the combination of scour at the toe of the bank
and the high velocity along the face of the bank during the high runoff periods
have taken this rip-rap out. This indicates the necessity of placing heavy
class "B" rip-rap along the exposed outer bank of the curved sections in
meander channels. The excavation for and placement of rip-rap below the
grade of the stream bed and extending out from the toe (Fig. 6) is necessary
to prevent the scour from undercutting the bank rip-rap.
One deficiency in the meander channels is noted in Figs. 29a and 29b.
The rip-rap extends to bank height and the establishment of natural vegetation
along the normal river flow line is not possible.
It was noted that filamentous algae had become established on the bed
and rip-rap in the Hazel Marsh Meander and appeared to be as abundant as in
the control sections. Algae is important in food -chain relationships and
may provide some cover for small fish.
-36-
6. CONCLUSIONS AND RECOMMENDATIONS
6.1 Conclusions
This evaluation of the two meander channels constructed to regain the
length of stream lost in eight channel changes in the Clark Fork River due
to the construction of Interstate Highway 1-9.0 west of Drummond, Montana
shows that :
a, the meander channels constructed do provide h}Tdraulic,
topographic ar^d fish habitat characteristics similar to those
found in uatural meanders,
t. fish of the same size, species and quantities found
in similar nat iral meanders of the river were also found in the
constructed meander channels three years after construction,
c. the method and criteria used in the design of the
meander channel was adequate to provide habitat for the trout and
whitefish native to this section of the river, and
d. the mark-and-recapture method of estimating fish popula-
tion provided adequate data for comparing the population in a
constructed meander with that in a natural meander of the river
although the confidence limits on the estimates of the absolute
number of fish in the sections sampled were not as low as can be
obtained by this method.
6.2 Discussion
The above-listed conclusions must be interpreted subject to the following
conditions :
a. The results and conclusions are biased toward the comparison
of the conditions in the Hazel Marsh Meander (C2) with those in the
Enman Meander (N4) as these were judged to have the greatest similar-
ity and were studied more intensively than the other meanders.
b. The results and conclusions are good for mountainous trout
streams with the type of bed material, gradient, planimetric con-
figuration and rip-rap material encountered in this study. The
variability of these parameters and others with the individual streams
-37-
and with different locations in the same stream make it inadvisable
to extrapolate these results to other cases.
c. The depth and velocity of flow during the fish population
sampling and the overall size of the river were greater than
normally encountered for the electrof ishing to be effective. The
techniques and analysis for streams of this size have not been
developed to as high a degree of accuracy as for the smaller trout
streams. For this reason the fish data are good for comparing the
populations of the two meanders but are not as reliable for the
absolute population estimates as have been obtained using the mark-
and-recapture method on smaller streams.
The backwater effect created by the construction of the meander channels
could not be evaluated. The average gradient of the stream bed between the
end points of the Hazel Marsh Meander (C2) was reduced from 17.5 to 9.5 ft
per mile; that for the Weaver Meander (CI) from 12.1 to 7.4 ft per mile.
The effects of gradient changes of this magnitude require the knowledge of
the hydraulic, topographic, planimetric and fish habitat conditions upstream
and downstream from the constructed meander prior to any alteration of the
channel. In addition to recovering the stream length, decreasing the gradi-
ent, and increasing the sinuosity and pool frequency in the constructed
meander, similar effects may occur in short reaches of the river upstream.
6 . 3 Recommendations
As a result of this evaluation study a number of recommendations can be
made on the procedure for designing meander channels with fish habitat con-
siderations and for conducting future studies to augment the proposed design
procedure.
6.3.1 Design procedure
The number of parameters involved in designing a meander channel with
suitable habitat for supporting trout varies from stream to stream and
between locations on the same stream to such an extent that a strict codified
design procedure cannot be formulated at this time. The field work, quanti-
tative data and other observations associated with this evaluation of two
meander channels constructed to restore fish habitat provide a basis for
recommending the following design guidelines :
-38-
a. A study of the geomorphology of the stream will show the
type of stream being dealt with and what its natural tendencies
are toward meandering. This may be aided by photogrammetry and
field observations.
b. A study of the hydraulic, topographic, and planimetric
conditions of the stream in the area of a proposed channel change
will establish the design criteria for integrating the constructed
section into the natural environment. The data obtained should
include high and low discharge rates, channel gradient, typical
cross-sections in meander curves, average stream width and general
planimetric configuration of meanders.
c. The design of a typical uniform cross-section based on
the hydraulic characteristics of the natural stream and held
constant throughout the curve of the meander channel will simplify
the construction. This cross-section should be of designed to
allow the scour and deposition of bed materials to occur with
a minimum movement of material (i.e., deep toward the outside of
the curve with a gradual slope back toward the inner bank) .
d. The design of the bed gradient as a series of relatively
flat slopes interspersed with occasional steep (riffle) sections
will accelerate the scour and deposition processes in attaining
a natural state. A steep gradient skewed across the stream in
the riffle areas should be located downstream from the inflection
points of the main curve at the inflow and outflow sections of the
meanders. These riffles will provide the cross-over sections for
the current.
e. The random placement of rip-rap containing a high per-
centage of pieces with volumes greater than one cubic yard each
will provide bank stability and create a diversity of habitat for
aquatic life. Rip-rap should be placed as steep as practicable
within the slope stability limitations of the bank. The toe of
the rip-rap should extend out into the stream and to a depth
below the design bed grade to prevent scour holes from undercutting
the rip-rap. The depth of the scour holes and their proximity to
the bank may be based on data obtained from conditions in natural
meanders of the same river having similar geometry, bed material
and gradients.
f . The design of the rip-rap section with fine bed material
placed slightly above the design high water level will allow
vegetation to be established. Eventually the vegetation will
provide shade and cover for the fish habitat and a more aesthetic
natural-appearing streambank.
g. The aquisition of right-of-way for meander channels
with allowance for a walkway on the top of the bank on at least
one side of the stream will provide fisherman access to the
stream. Without this provision the restoration of fish habitat
through constructed meanders loses its purpose.
6.3.2 Future studies
The number of parameters enterring the design of meander channels with
suitable habitat for trout does not permit an effective study of this problem
to be conducted in a given laboratory type experimental investigation much
less by analytical analysis and mathematical modelling alone. The approach
suggested for future research is that of the case study. This requires the
complete documentation of the effects of channel changes on fish habitat
for selected specific cases, including those previously constructed and those
planned for future construction. The results from case studies will be used
to modify and improve the guidelines and criteria listed in previous
paragraphs .
Specific recommendations for future studies include:
a. A conference should be initiated with the personnel from the Planning
and Research Section of the Montana Highway Department to ascertain the
number and location of highway projects requiring channel changes in trout
streams within the next 5 to 10 years.
b. A program should be established for studying the streams in those
areas where channel changes may be required. These studies would include
obtaining data on fish population, streamflow records, bed materials, flow
line profiles, planimetric configurations and stream geomorphology . It is
important Lo obtain data on baseline conditions prior to construction to
-40-
afford a basis of comparison with conditions after alterations have been
effected.
c. Selected channel change sections previously constructed should be
chosen for study of fish population, hydraulic and topographic data. The
hydraulic and topographic data from these sections would be compared with
the construction plans to determine the changes which have occurred over
the years. The fish population estimates would be compared with similar
data from other sections of the same river to determine the effect of the
channel change on the fish population after a period of several years.
d. The Hazel Marsh Meander and the Enman Meander should be monitored
for fish population estimates and changes in bed topography at 3-year
intervals to form a continuous record of changes in these test sections.
e. A comprehensive economic analysis should be carried out on a future
channel change involving the construction of a meander to restore fish
habitat to determine the cost-benefit ratio of such projects.
f. A study of the effects of the proximity of the constructed meander
channel to the section of stream altered by the highway location should be
conducted. Two meander channels totalling approximately 5200 ft of new
channel were constructed to recover approximately 1750 ft of channel length
lost in eight sections of stream altered for highway location. The eight
sections are located over a 7-mile length of highway. The stream lengths
lost in the individual alternations range from a maximum of 485 ft to a mini-
mum of 80 ft. The gradient changes (average AS = +0.02%) in the individual
altered sections are much less than the gradient changes (average AS = -0.12%)
between the end points of the constructed meanders (ref. Table 1). The Hazel
Marsh Meander (C2) is located immediately upstream from one altered section;
the Weaver Meander (CI) is 2250 ft upstream and 4200 ft downstream (highway
stationing) from the nearest sections altered by the highway location. Other
than recovering the length of stream lost the effects of the two constructed
meanders on the reaches of the river immediately upstream and downstream
were not determined. It may be better from the consideration of the stream
hydraulics and from the economics to recover the stream length in short
sections close to the alterations caused by highway locations rather than
regaining the length in one or two long meanders some distance away.
-41-
LITERATURE CITED
Elser, A. A.
1968. Fish populations of a trout stream in relation to major habitat
zones and channel alterations. Trans. Amer . Fish. Soc. 97(4):
389-397.
Johnson, R. L.
1964. Southwest Montana fishery study — stream channel alteration
survey — Shields River. D. J. Completion Report, Project
F-9-R-12. Mont. Fish and Game Dep., 4 pp.
Leopold, L. B. and Langbein, W. B.
1966. River meanders. Sci. Amer. 214 (6) : 60-70 .
, Wolman, M. G., and Miller, J. P.
1964. Fluvial processes in geomorphology . W. H. Freemand & Co.,
San Francisco. 522 pp.
Lewis, S. L.
1969. Physical factors influencing fish populations in pools of a trout
stream. Trans. Amer. Fish. Soc. 98(1): 14-19.
Ricker, W. E.
1958. Handbook of computations for biological statistics of fish
populations. Fish. Res. Bd . Canada, Bull. 119. 300 pp.
Swedberg, S. E.
1965. Central Montana fisheries study — evaluation of fish habitat
destruction in Prickly Pear Creek due to construction of Inter-
state Highway 1-15. D. J. Completion Report, Project F-5-R-13.
Mont. Fish and Game Dep., 14 pp.
Whitney, A. N. and Bailey, J. E.
1959. Detrimental effects of highway construction on a Montana stream.
Trans. Amer. Fish. Soc. 88(1): 72-73.
-42-
APPENDIX
GRANITE COUNTY, MONTANA
A-2
Fig. 2. WEAVER MEANDER
A-3
Fig. 3. HAZEL MARSH MEANDER
A- 4
<£ MEANDER CHANNEL ^
JatBg
8
A-6
(a) TYPICAL SECTION OF CHANNEL
IN CURVE OF MEANDER
CONSTRUCTED CHANNEL SECTIONS
FIG 6
A- 7
Fig. 7. DOWNSTREAM MEANDER NO. 1
A-8
Fig. 8. DOWNSTREAM MEANDER NO. 2
A-9
Fig. 9. NELSON MEANDER
A-10
Fig. 10. ENMAN MEANDER
Id '1H9I3H
0'
(a) PL AN VIEW
200
_L
400'
J
WATER SURFACE
\
\
\
\
\ r
\ / THALWE8
f 8/15/71
\
\ /
\ '
\ '
\ 2 )
V
j SA i l.
500 1000
CHANNEL DISTANCE, FT
(b) PROFILE VIEW
0
(c) CHANNEL CROSS-SECTIONS
(8/15/71)
EVALUATION OF CHANNEL CHANGES
IN CLARK FORK RIVER
CHANNEL SECTIONS S PROFILES
DOWNSTREAM MEANDER NO (Nl)
A-13
2 000
I 1 1 1 1 1 1 I l_
0 500 1000 1500 2000
CHANNEL DISTANCE, ft
(b) PROFILE VIEW
EVALUATION OF CHANNEL CHANGES
IN CLARK FORK RIVER
CHANNEL SECTIONS 6 PROFILES
DOWNSTREAM MEANDER NO 2 (N2)
FIG. 13
800
• BE 0 SAMPLE
0 500 1000 1500
CHANNEL DISTANCE , FT
(b) PROFILE VIEW
FIG. 14
A-lU
©
©
EVALUATION OF CHANNEL CHANGES
IN CLARK FORK RIVER
CHANNEL SECTIONS 8 PROFILES
NELSON MEANDER (N3)
B -
0 500 1000 1500
CHANNEL DISTANCE, FT.
(b) PROFILE VIEW
FIG. 15
A-15
HOf? DIST , FT
(c) CHANNEL CROSS-SECTIONS
(3/23/72)
EVALUATION OF CHANNEL CHANGES
IN CLARK FORK RIVER
CHANNEL SECTIONS 8 PROFILES
ENMAN MEANDER (N4)
A-l6
0
WATER SURFACE
1 I 1 I 1 I
0 20 40 60
H OR OIST , FT
AS STAKED
9/3/68
(c) CHANNEL CROSS SECTIONS
(8/24/71}
THALWEG
8/24/71
_l_
CD
■ i_
© 0 © ©
ij i i i_
-L
25+00 20+00 15+00 10+00
CHANNEL STATIONS (MHO CONSTRUCTION NOTES 9/3/68)
(b) PROFILE VIEW
5 + 00
FIG. 16
EVALUATION OF CHANNEL CHANGES
IN CLARK FORK RIVER
CHANNEL SECTIONS & PROFILES
WEAVER MEANDER (CI)
A-17
_ — — «■
EVALUATION OF CHANNEL CHANGES
IN CLARK FORK RIVER
CHANNEL SECTIONS a PROFILES
HAZEL MARSH MEANDER (C2)
20*00 15*00 10 + 00 5+00
CHANNEL STATIONS (MHD CONSTRUCTION NOTES 5/23/68)
(b) PROFILE VIEW
FIG 17
/J
A-21
A-22
A-23
o-o o
o-
©
4-
o
"□
- a.
DO-
©
o-'0--°-°-o
I
-on
®
I
□-o
O 15 00
□ 14 00
□
<5- □
©
.JD--0-
OD-
s
-□o
O 12 00
□ II 00
©
0 — '
5—,
0—1
5—i
0 — I
/
•o -
/
/
5—,
0— 1
5—1
0— 1
CO
CL
Ll_
o
_l
UJ
>
P-O-O
\
O
/
\
o-,
,o-o-_,
-o a
s
©
i 1 r
60 40 20
n i I
20 40 60
TRANSVERSE DIST., FT.
(a) HAZEL MARSH MEANDER
( CONSTRUCTED)
3/22/72 - 1225 cfs
5—i
0— 1
5—,
.-°-J-o
/ - -o C- _
60
i r
i
20
40 20 0 20 40
TRANSVERSE DIST., FT.
(b) ENMAN MEANDER
( NATURAL)
3/24/72 - 995 cfs
~1
60
TRANSVERSE VELOCITY DISTRIBUTION
FIG. 23
A-24
b. Material at upstream end of bar
Fig. 24. SIZE DISTRIBUTION OF BED MATERIALS
A- 25
b. Material at downstream end of bar
Fig. 25. POINT BAR DEPOSITS, HAZEL MARSH MEANDER
A-26
b. Material at downstream end of bar
Fig. 26. POINT BAR DEPOSITS, ENMAN MEANDER
A-27
b. Upstream from Section 6
Fig. 27. STREAM FLOW CROSS-OVERS, ENMAN MEANDER
A-28
A-29
b. Downstream from Sta. 22+00
Fgi. 29. STREAM FLOW CROSS-OVERS, HAZEL MARSH MEANDER
A-30
b. Flow around single rock
Fig. 30. FLOW NEXT TO RIP-RAP, HAZEL MARSH MEANDER
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