Environmental Impact Statement - Sonoma Land Trust

California Department of Fish and Game
U.S. Fish and Wildlife Service
Section 3.5. Biological Resources
These actions would alter the hydrologic regime, which may result in conversion
of some seasonal wetlands to perennial marsh. A benefit of this action would be
to reduce the abundance of non-native invasive species by removing seeds
contained in the topsoil and by lowering the nutrient load associated with
manure-enriched soils that favor invasive species. It may also increase the overall
level of wetland functions, and benefit waterfowl by providing more perennial
marsh habitat. While these enhancements may result in some degree of
conversion of seasonal wetlands, this would be offset by the increase in wetlands
and habitat function provided by such enhancements. Additionally, none of the
proposed breaching options would change the acreages of Project impacts on
seasonal wetlands. ; this loss would be offset by the increase in habitat function
provided by the enhancements. Therefore, impacts of the Proposed Project on
seasonal wetlands are overall considered less than significant, and no mitigation
is required.
Conclusion: Less than Significant.
Full-Tidal Alternative
Impacts from the loss of seasonal wetlands north of Highway 37 resulting from
enhancement activities under the Full-Tidal Alternative would be the same as
that described above for the Project. South of Highway 37, the Full-Tidal
Alternative would include excavating an interior channel network, grading to
establish topographic features, construction of new levees as flood protection to
Highway 37, Reclamation Road and the SMART rail line, and establishing a long
duration hydrologic regime. These activities would remove the existing
vegetation and promote the establishment of tidal marsh vegetation. A
consequence of these restoration activities would be the loss of approximately
30.9 acres of vernal pools, 94.98 acres of farmed seasonal wetland, and 41.4
acres of seasonally saturated annual grasslands by conversion to tidal marsh. or
new levees. These seasonal wetlands were not present on the site historically, and
their commensurate wetland functions are severely degraded by disturbance and
nutrient loading. These wetlands provide lower habitat value and do not provide
the historical functions and values of tidal baylands. Restoring tidal marsh would
re-establish the historic plant community and would result in much higher levels
of wetland function, including conditions suitable for special-status species not
currently known onsite (California clapper rail, salt marsh harvest mouse,
California black rail). Therefore, impacts of the Full-Tidal Alternative are
considered less than significant, and no mitigation is required.
Conclusion: Less than Significant.
Sears Point Wetland and Watershed Restoration
Project Final Environmental Impact
Report/Environmental Impact Statement
3.5-32
April 2012