The Loma Prietan - November/December 2009

The Egret has landed. Restored wetlands in the South Bay are bringing back birds and marsh vegetation faster than expected. Photo: John Gibson, GOT Imaging

The South Bay Salt Pond Restoration Project is making significant changes to the Bay Area environment. The changes implemented to date are aligned with three key goals: habitat restoration, flood protection, and public access. Salt ponds returned to tidal action are re-establishing marsh vegetation more rapidly than anticipated. A study is underway to determine the flood risk in the shoreline area, including a risk projection that extends more than 50 years. A new section of the Bay Trail, viewing platforms, and interpretive stations are slated to be built.

Several salt ponds were reintroduced to tidal action in early 2006. Since then, enough silt from the Bay has been deposited so that marsh vegetation and bird use of the ponds have increased considerably. This is good news, as it can take up to eight years for a marsh to start to come back. Restoring these ponds provides needed feeding zones for shorebirds that migrate through on the Pacific Flyway. The western snowy plover, a threatened species, is already showing signs of increased activity in the new pond habitat. The sloughs and channels meandering through the marsh create a protective nursery for young fish like steelhead.

Climate change and the expected rise in sea levels present challenges regarding flood protection. Tidal wetlands are a natural buffer against flooding, absorbing heavy rain runoff during a storm and slowly releasing it into the Bay. Tidal marshes rise with the sea level, accumulating silt and sediment in a way that preserves the marsh over time. Historical floodplains will need to be redefined to account for the expected sea-level rise. A recent study by the Pacific Institute projects that the Bay's level will rise 1 — 1.4 meters by 2100, due to an expected warming of the climate.

The restoration project is collaborating with the Army Corps of Engineers, Santa Clara Valley Water District, and California State Coastal Conservancy to design a comprehensive flood control plan that will successfully incorporate habitat restoration and wetlands. A baseline study will quantify the flood risk to Silicon Valley today and 50 years into the future. A zone comprising most of the Silicon Valley shoreline is designated by FEMA (Federal Emergency Management Agency) as a 100-year flood area, with a 26% chance of a flood over the life of a 30-year mortgage. The Pacific Institute study titled "Impacts of Sea Level Rise on the California Coast" identifies a number of public facilities and neighborhoods that might be affected by tidal flooding.

The third goal of the Project is to provide greater public access in the wetland areas. A 2.2-mile section will be added to the San Francisco Bay Trail, to connect existing segments in Mountain View and Sunnyvale. At Bedwell Bayfront Park in Menlo Park, a viewing and interpretive station will be built overlooking the Ravenswood ponds. Near the Dumbarton Bridge, two viewing platforms with interpretive stations will be added.

The restoration project is happening because 16,500 acres of former salt ponds were placed in public ownership and saved from private development; it will take decades to fully complete. Some salt ponds have been placed back into tidal action, and the transformation into wetland habitat has begun faster than expected. Flood control is a critical goal, with a long-term solution needed to manage and mitigate the effects of sea-level rise. The restored tidal wetlands will be incorporated into the flood-control design. Thanks to the public- access component of the plan, we will all be able to experience the wonder, beauty and diversity of a vibrant wetland environment in the South Bay.

David Walling is a member of the Chapter's Wetland Subcommittee.