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William F. Weld

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Local Distribution and Use of Wetlands Conservancy
Program Orthophoto Maps

The Wetlands Conservancy Program in the Department of
Environmental Protection's Division of Wetlands and Waterways has
developed "orthophoto" maps to accurately locate and delineate
the state's wetland resources. In addition, these maps are an
excellent medium-scale (1" = 417' scale) planning tool. The
"photo base" of the maps makes them an extremely accurate and
comprehensive record of the community at a scale that displays
features on the individual parcel level. As a result, these maps
have a broad range of potential uses for municipal governments.

For this reason, the Wetlands Conservancy Program is giving
a full set of these orthophoto maps free of charge to each
community through its Conservation Commission. The following is
a list of possible municipal uses for these photo-based maps.

CONSERVATION COMMISSION POTENTIAL USES

Project Review and Permitting Issues:

These maps include "photo-interpreted" wetland delineations
that provide an accurate inventory of the town's wetlands.
As a result, these maps can serve as an atlas of the
community's wetland resources.

The wetland delineations shown on these maps
do not substitute for a field delineation under
Massachusetts General Laws c.131, §40 (the
Wetlands Protection Act) .

— Commissions should encourage project proponents to review
the maps and discuss possible wetland regulation
implications with the Commission prior to the submission of
a Request for Determination of Applicability or Notice of
Intent .

Ongoing projects can be recorded on the maps. Symbols can
be color-coded to easily communicate the status of each
project.

One Winter Street • Boston, Massachusetts 02108 • FAX (617) 556-1049 • Telephone (617) 292-5500

Conservancy Maps/Page 2

Wetlands within the community that have not been included
in the photointerpretation process could be displayed.
These areas will become evident during the normal course of
business during the Commission's on-site visits and also
could come from local knowledge. This locally developed
wetland data will be very useful when the statewide wetland
data layer is updated. It is anticipated this will be
conducted in ten year intervals.

— Project alternatives - an important part of the project
review process - can be more easily visualized using these
maps.

The cumulative effects of multiple projects can be better
evaluated and understood by seeing the projects displayed on
the maps.

It is important to note that the wetland delineations on
these photo-based maps are photointerpreted and thus
represent a very accurate inventory of wetlands but do not
replace the wetland boundary that is determined by an
on-site investigation under the Wetlands Protection Act.

Natural Resource Issues:

Impacts of projects that are outside the town's borders can
be better recognized and understood with these maps. Since
these maps are not limited by municipal boundaries, the maps
of one town also include some areas of adjoining
communities.

Ecosystems can be visualized on the maps as a unit
within the context of the developed community.

— FEMA flood zones and velocity zones can be drafted

onto the maps. By displaying this data on the maps at a
larger scale than the FEMA maps, the data will be easier to
visualize.

River watershed basin boundaries can be displayed on
the maps. Also, the maps can provide better projected
runoff estimates as compared to the USGS topographical maps
currently used.

— Estimated rare and endangered species habitats can be
displayed on the maps. The large scale of the maps makes
habitat analysis possible without lengthy field work.

Vernal pools can be displayed on the maps.

Public and private drinking water wells can be displayed.

Conservancy Maps/Page 3

Also, the watershed areas contributing to these important
resources can be delineated and regulated.

The community's open space and conservation land can be
delineated on the maps. Management of these lands can be
coordinated using the maps. Proposed new acquisitions can
be better visualized on the maps.

Known areas of hazardous contamination and pollution can be
accurately displayed and investigated.

It is important to note that the wetland delineations on
these photo-based maps are photointerpreted and thus
represent a very accurate inventory of wetlands but do not
replace the wetland boundary that is determined by an
on-site investigation under the Wetlands Protection Act.

PLANNING BOARD POTENTIAL USES

— These maps provide an accurate planning scale inventory of
the community's wetlands, highway infrastructure, and real
estate base.

— The accuracy of the maps would allow them to be used as a
base for any type of zoning overlay district. These maps
exceed National Map Accuracy Standards.

— If the separate map sheets were joined together to make one
community map, it could serve as a photo-based zoning map.

The maps could serve as a base upon which to develop "build-
out" projections. Since every square inch of the
community's land area is photo displayed, a complete
assessment of developable land is possible.

— Transportation planning can be more easily conducted using
the maps of the community's roads and highways.

BOARD OF HEALTH POTENTIAL USES

Often, the Board of Health doesn't have the expertise to
accurately determine the upland limits of wetlands. As
the Massachusetts Title 5 regulations require setbacks from
wetlands, the maps will be used frequently by health agents
and developers working with the Conservation Commission.

The maps can be used to display soils information, which is
important in the location of properly-functioning septic
systems. Also, observed groundwater levels could be
displayed on the maps.

Conservancy Maps/Page 4

Percolation (perc) test records can be displayed on the maps
to provide information about poorly-drained sites.

The maps provide a visual base for a community's
epidemiological studies, such as outbreaks of Lyme Disease
and giardia, as well as other health issues that require the
use of geographic referencing.

The maps can be used to more effectively direct seasonal
mosquito control activities by identifying wetland target
sites for specific mosquito control applications, thus
eliminating the need for expensive field reconnaissance; and
by identifying sensitive receptors and "no spray zones,"
maximizing the mosquito control strategy to the intended
sites.

HAZARDOUS WASTE COMMITTEE POTENTIAL USES

These maps could serve as a visual inventory of:

— known hazardous waste clean-up sites;

— underground fuel storage tanks. Tank inspections

and leak history can be recorded on the maps; and

— known hazardous waste storage facilities (this data

can be shared with the fire and police
departments) .

BUILDING INSPECTOR POTENTIAL USES

The maps provide an inventory of a community's
wetlands data, which could be consulted when issuing
building permits. (FEMA floodplain information also could be
included. )

A full set of these maps can be displayed within or near
the Building Inspector's Office for informational purposes.

ASSESSOR'S OFFICE POTENTIAL USES

These photo-based maps can be used as a visual reference for
locating property on the appropriate tax map.

The maps serve as an accurate historical record of all
the real estate parcels (and rights-of-way) within a
community.

Conservancy Maps/Page 5

There is the potential to use the photo-based maps as a
medium-scale base in a GIS of taxable properties within the
community. This Land Information System could include
parcel attribute data and other sociological information
important to the community's database.

[See below for a discussion of digital potential for the map. ]

SELECTMEN'S OFFICE POTENTIAL USES

A set of the maps can be prominently displayed in a very
accessible location in the Town Hall Building. All levels
of municipal government might be encouraged to use them.

POLICE AND FIRE DEPARTMENT POTENTIAL USES

The maps could be used to develop an emergency response
database.

DEPARTMENT OF PUBLIC WORKS POTENTIAL USES

The maps provide a photo base of all facilities and
structures and could be useful in facility and maintenance
planning.

POTENTIAL DIGITAL APPLICATIONS OF THE ORTHOPHOTO BASE MAP

Here are two of the many uses for the digital version of the
photo-based maps:

1. Digital scanning of the orthophoto map produces a raster file
with approximately 0.5 meter resolution. The file size is 25
megabytes. This product would provide personal computer terminal
access to the map data. Information such as roads,

utilities, and structures could be taken from the computer screen
in vector form.

2 . Tax parcel map data can be combined with the raster base or a
photographic image of the orthophoto map to register that data to
the medium-scale accuracy of the map series. This product would
provide the community with a photo-based correction of the tax
map series. As with all tax map data, the maps represent only an
approximation of the deed-defined parcel dimensions, but the
combined map connects the tax parcel map series to the ground
control network of the orthophoto maps.

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