mitigation
mitigate (mit'-i-gat) v. -gated -gating.
To make or become less in force or intensity; moderate.
Prior to the enactment of the 1972 Clean Water Act, it is likely that construction of
all man-made lakes and reservoirs in eastern Virginia impacted wetlands. The Clean
Water Act requires that
 impacts to wetlands be addressed. During the planning stages
of this project, 216 acres of wetlands were avoided by reducing the size of the
lake. However, impacts to 403 acres of non-tidal, vegetated wetlands could not be
avoided and those losses
will be compensated by replacing them at a ratio of two for one (2:1).
The mitigation
plan approved by the US Corps of Engineers and the Virginia Department of Environmental
Quality will create and restore 806 acres of wetlands. In addition, another 300
acres of wetlands will form along the shore of the lake; the project will preserve
another 400 acres of wetlands along with 3,500 acres of upland buffer zones. The
complete mitigation proposal developed by the project partners preserves more than
6,000 acres in the Chesapeake Bay watershed from future development and is the single
largest contribution towards Virginia’s pledge to restore 20,000 acres of wetlands
by 2010 to clean up the Chesapeake Bay. Click on a tab below for more information.
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Fisheries |
Streams |
Uplands |
Wetlands |
Fisheries mitigation requirements are included in the State and Federal permits issued for
the project. The mitigation falls into 3 general categories; passageway improvements for spawning, hatchery
augmentation, and in-river protections. In-river protections include custom
designed intake facilities with time-of-year construction limitations, and operating
rules to limit withdrawals during low flow periods and during peak spawning periods
for American Shad.
Over $5 million will be spent to research, design and implement all of the fisheries
migratory projects. This amount does not include an endowment that will be established
to continue research and protective measures in the Mattapoini River watershed.
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Fisheries mitigation requirements are included in the State and Federal permits issued for
the project. The mitigation falls into 3 general categories; passageway improvements for spawning, hatchery
augmentation, and in-river protections. In-river protections include custom
designed intake facilities with time-of-year construction limitations, and operating
rules to limit withdrawals during low flow periods and during peak spawning periods
for American Shad.
Over $5 million will be spent to research, design and implement all of the fisheries
migratory projects. This amount does not include an endowment that will be established
to continue research and protective measures in the Mattapoini River watershed.
Cohoke Creek and tributary stream channels
flooded by the lake will be compensated by restoring, enhancing and preserving many
miles of similar streams throughout the York River watershed. Also, working in
cooperation with state agencies, fish passage will be restored on at least one river
in the York River watershed that is currently blocked by a dam or other obstruction.
More than 3,000 acres of upland protection and restoration are being
incorporated into the mitigation elements of the King William Reservoir
Project. This acreage is crucial to establishing hydrologic and habitat
buffers to the wetland and stream mitigation corridors. The upland acreage
includes a 100 ft. buffer around the reservoir normal pool elevation of +96 feet
mean sea level. More than a third of the total is devoted to buffers
surrounding wetland restoration and creation sites. Additionally, upland
preservation is required downstream of the dam, within the Cohoke Creek watershed.
The water quality benefits of upland buffers is well documented in watershed
protection and stream protection design manuals. Upland buffers and forests
are also an important component of the Chesapeake Bay Program protections.
The Chesapeake Bay Program provides important information on the role
of
forested buffers. The
upland buffers being protected
and restored by this project are in addition to the wetland and stream mitigation
acreage.
The dam and reservoir on Cohoke Creek
will flood 437 acres of wetlands and other “waters of the United States” but
their ecological functions and values will be fully replaced through a program
of compensatory mitigation. The area includes 34 acres of open
water that will be replaced by the 1,500-acre lake.
The remaining 403 acres of
vegetated wetlands will be replaced on a 2-for-1 basis by restoring former wetlands
or creating new ones along the Pamunkey and Mattaponi Rivers and their tributaries,
primarily in areas that had been wetlands before they were ditched or drained for
farming.