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Environmental Impact Statement - Sonoma Land Trust

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California Department of Fish and Game<br />

U.S. Fish and Wildlife Service<br />

Section 3.3. Water Quality<br />

warning of potential bioaccumulation and biomagnification due to methyl<br />

mercury. The monitoring of sentinel species can be used to identify when trigger<br />

levels may be reached at which time corrective actions would be taken to reduce<br />

associated risks with increased methyl mercury levels.<br />

Corrective actions could include changes in water management, changes in<br />

vegetation conditions through plantings or other measures.<br />

The methyl mercury adaptive management plan shall be modified as necessary to<br />

reflect increased understanding of mercury cycling in San Francisco Bay.<br />

Conclusion: Less than significant with mitigation.<br />

Full-Tidal Alternative<br />

As above, there is a potential for increased methyl mercury concentrations under<br />

the Full-Tidal Alternative and resulting bioaccumulation and biomagnifications<br />

impacts. Mitigation Measure WQ-MM-3 is recommended2 would be<br />

implemented to minimize this impact.<br />

Conclusion: Less than significant with mitigation.<br />

<strong>Impact</strong> WQ-3: Degradation of Groundwater Quality<br />

Because the groundwater table at the proposed wetland restoration site is shallow<br />

(and even creates surface ponding of emergent groundwater during the wet<br />

season), there is potential for contamination of groundwater supplies during<br />

contact with surface water and soils.<br />

Proposed Project<br />

Inundation of the wetlands restoration area could degrade shallow groundwater<br />

through saltwater intrusion or leaching of hazardous materials. However, the<br />

shallow groundwater in the expansion area south of the SMART railroad tracks<br />

already has a high salinity because of the historic influence of San Pablo Bay.<br />

Because of the presence of Bay muds at the site, surface water and shallow<br />

groundwater are unlikely to recharge deeper groundwater aquifers. As such,<br />

potential exchange of saline water contaminants between surface water and<br />

shallow groundwater are considered less than significant, and no mitigation is<br />

required.<br />

Conclusion: Less than Significant.<br />

Sears Point Wetland and Watershed Restoration<br />

Project Final <strong>Environmental</strong> <strong>Impact</strong><br />

Report/<strong>Environmental</strong> <strong>Impact</strong> <strong>Statement</strong><br />

3.3-18<br />

April 2012

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