Environmental Impact Statement - Sonoma Land Trust

California Department of Fish and Game
U.S. Fish and Wildlife Service
Section 3.2. Surface-Water Hydrology,
Tidal Hydraulics, and Sedimentation
quality within the Bay. Per the San Francisco Bay Plan, dredging should be
authorized when the BCDC can find:
• the applicant has demonstrated that the dredging is needed to serve a wateroriented
use or other important public purpose, such as navigational safety;
• the materials to be dredged meet the water quality requirements of the San
Francisco Bay RWQCB and the inter-agency San Francisco Dredged
Material Management Office (DMMO);
• important fisheries and Bay natural resources would be protected through
seasonal restrictions established by CDFG, USFWS, and/or the National
Marine Fisheries Service (NMFS), or through other appropriate measures;
• the siting and design of the project would result in the minimum dredging
volume necessary for the project;
• the volume to be disposed is consistent with applicable dredger disposal
allocations and disposal site limits adopted by the BCDC by regulation; and
• disposal would be at a site designated by the BCDC.
A permit will be granted for a project if BCDC finds and declares that the project
is either (1) necessary to the health, safety, or welfare of the public in the entire
Bay Area; or (2) of such a nature that it will be consistent with the provisions of
this title and the provisions of the San Francisco Bay Plan then in effect.
Topography
The project site partially consists of former tidal marshlands that were
historically diked and isolated from tidal action to permit agricultural use.
Topographic relief in this area is low and gradients are gentle. A regional
location map that indicates the location of the major surface-water and tidal
channels in the vicinity of the project site is shown in Figure 3.2-1. The area to be
returned to full tidal action is about 955 acres in size and is bordered by the
SMART railroad to the north, San Pablo Bay to the south, and Tolay Creek to the
east. Ground-surface elevations in the area are now as much as 2–3 feet below
MTL (Moffatt and Nichol 2007). Subsidence has likely been an indirect result of
diking for agricultural use. In the absence of natural tidal action, the shallow soils
are no longer saturated; consequently, organic matter oxidizes and is reduced in
volume, leading to settlement.
Additional information about topography is located in Section 3.1, Geology,
Soils, and Paleontology and information about groundwater is located in Section
3.3, Water Quality.
Sears Point Wetland and Watershed Restoration
Project Final Environmental Impact
Report/Environmental Impact Statement
3.2-4
April 2012