Environmental Impact Statement - Sonoma Land Trust

California Department of Fish and Game
U.S. Fish and Wildlife Service
Section 3.4. Public Health and Safety
Action Alternatives
Impact PH-1: Increase of Potential Mosquito Breeding
Habitat
Proposed Project
The wetland habitats proposed to be created/restored in the project area include
tidal marsh, non-tidal seasonal wetlands, and upland seasonal wetlands.
The proposed restoration project involves breaches in the existing outboard levee
to restore full tidal action for the development of approximately 970-955 acres of
tidal marsh between the southern perimeter of the project site and the SMART
rail line. Tidal marsh in this area would be a mixture of subtidal, intertidal and
brackish open water habitat. Due to high salinities and rapidly fluctuating water
levels, tidal wetlands represent the least need for regular mosquito control.
Above the SMART rail line, the preservation and enhancement of 106-acres of
non-tidal wetlands , and the creation of 40-acres of seasonal wetlands north of
Highway 37 represents the most potential for producing problem numbers of
mosquitoes. Seasonal ponding in this area is also possible from brackish drainage
ditches, agricultural drainage ditches, and ponded areas within cultivated fields
that may hold water during the wet season. Within seasonal wetlands as well as
each of these areas, suitability for mosquito production varies, depending on
water/tidal currents, the extent and duration of ponding, and site-specific
salinities.
In general, the seasonal wetlands component of the Project in diked baylands and
north of the high tide limit represents the greatest potential need for additional
mosquito control, though the degree would be affected by site-specific design
and management.
The proposed creation of seasonal ponds to serve as breeding habitat for
California red-legged frogs also represents a potential increase in suitable
mosquito breeding habitat.
The potential mosquito breeding habitats resulting from the Project are quantified
in Table 3.4-1.
Tidal Marsh
The potential for mosquito production associated with tidal wetland and marsh
restoration is considered in three distinct phases over a period of several decades:
(1) preparatory water managementpre-vegetation; (2) early mudflat-marsh
succession; and (3) youthful tidal marsh.
The preparatory/temporary non-tidal phase involving flooding and draining is
expected to occur over two growing seasons. During the first year, the site would
alternate between prolonged periods of shallow open water and brief periods of
mud emergence. During flooding to create shallow open water, intake of Bay
Sears Point Wetland and Watershed Restoration
Project Final Environmental Impact
Report/Environmental Impact Statement
3.4-7
April 2012