Environmental Impact Statement - Sonoma Land Trust

California Department of Fish and Game
U.S. Fish and Wildlife Service
Section 3.5. Biological Resources
Willow Scrub
Riparian stands of willow scrub occur primarily in upper stream reaches of the
watershed 1 , totaling approximately 1.7 acres. Nineteen stands are present onsite,
ranging in size from single willows to small woodlands. The two willow species
present in these stands are arroyo willow and shining willow. The willows grow
within or immediately adjacent to the stream channel. The understory is
dominated by non-native weedy species. Birds found in this community are
similar to those found in brackish marsh communities described above.
Vernal Marsh and Vernal Pool
Approximately 35.2 acres of vernal marsh and vernal pools are present on the
Project site. Vernal marsh is a seasonal freshwater wetland dominated by
perennial grasses, rushes, and other grasslike species. Vernal marsh occurs in the
watershed, primarily in the floodplains of middle and lower stream reaches, and
along larger more meandering streams along the west side of the Project site. The
dominant species is brown-headed rush. Common associates include pale
spikerush, Baltic rush, alkali ryegrass, and meadow barley. In drier portions of
the vernal marsh, Italian ryegrass and Mediterranean barley are also common. In
the larger drainages in the western portion of the watershed, scattered semipermanent
scour pools are present that support cattails and other emergent marsh
species, including water plantain and Baltic rush. Other scour pools with more
seasonal hydrology lack cattails and support other species such as hedge nettle,
western mannagrass, and pale spikerush.
Birds found in brackish marsh communities would also likely be found in these
communities. In addition, because these communities contain more open water
areas, wading birds, shorebirds, and waterfowl, such as those previously
mentioned, would also likely frequent these communities. Bullfrogs and Pacific
tree frogs, and California red-legged frogs (a federally threatened species) are
also known to inhabit these communities and have been documented to occur
onsite in the northern portion of the Action areaproject site.
Vernal Pools
Vernal pools are present both in the watershed and in the diked baylands sections
of the Project site. In the watershed, vernal pools are present in slumps, in
landslide depressions, in scoured depressions within off-channel meander scars,
and in depressions within floodplains along the drainages. In the diked baylands,
some low lying areas have developed seasonal wetland hydrology and support
vernal pool vegetation. These vernal pools, also characterized in the data sources
as bayland seasonal pools or farmed wetlands, have low species diversity and are
disturbed by farming activities.
Most of the vernal pools have a high cover of western mannagrass and California
semaphore grass. Other common vernal pool species present are rayless
goldfields, bracteate popcornflower, Jepson’s button celery, and common
spikerush. Vernal pools support numerous aquatic insects and vernal pool
1 For planning purposes, the Sears Point site is broadly divided into two landscape units—diked baylands and watershed. Mean
higher high water (+6.4 foot contour) represents the approximate boundary between these units.
Sears Point Wetland and Watershed Restoration
Project Final Environmental Impact
Report/Environmental Impact Statement
3.5-13
April 2012