Approximately 85% of the tidal marshes that once surrounded San Francisco Bay have been converted over the past 150 years to salt production ponds, agricultural lands, and urban development.  San Francisco Bay is ecologically important both nationally and globally, supporting commercial and recreational fisheries, providing key habitat for migratory shorebirds and waterfowl along the Pacific Flyway, and providing vital habitat for endangered species.  San Francisco Bay is a shallow estuary with high sediment loads from natural sources and from California’s legacy of hydraulic gold mining.  The Bay’s major ship channels require frequent dredging to maintain safe and efficient navigation.  Channel deepening is occasionally required as the ships used for international trade increase in size.  In recent decades, nearly all non-contaminated dredged material was dumped at open water disposal sites in the Bay, with the expectation that the dredged sediments would be dispersed by strong tidal currents.  During the 1980’s, it became apparent that the capacity of the main disposal site near Alcatraz Island was being exceeded and that alternative disposal options were sorely needed.  A Congressionally-authorized project to deepen Oakland Harbor’s channels to 42 feet was stymied in the early 1990’s by the lack of an environmentally acceptable and economically feasible plan for disposal of the dredged material.

The Sonoma Land Trust and the California State Coastal Conservancy conceived and developed the Sonoma Baylands project to protect and restore agricultural lands, seasonal wetlands and tidal salt marsh on a 830-acre parcel of land.  As part of that overall project, the Conservancy funded the development of a plan to restore tidal salt marsh on a 320-acre hayfield on the shoreline of San Pablo Bay.  The Conservancy’s restoration consultant recommended the use of dredged material to accelerate the restoration of salt marsh on lands that had subsided up to six feet.  Initial plans anticipated that only a small quantity of dredged material would be available for use in the restoration project.  Planners from the U.S. Army Corps of Engineers, San Francisco Bay Conservation and Development Commission, California Department of Fish and Game, and other agencies recognized that the Sonoma Baylands project could help resolve the dredging deadlock that had stalled Oakland Harbor and other economically-important dredging projects.  The Coastal Conservancy’s final plan for the Sonoma Baylands project called for the use of about two million cubic yards of dredged material to provide the optimum base elevation for the natural formation of a salt marsh through tidal action, sediment deposition, channel formation and colonization by native marsh vegetation and wildlife.

 After the Coastal America program was initiated in 1992, a 39-acre pilot project at Sonoma Baylands was identified as one of the first two Coastal America projects that would be implemented by the Corps of Engineers.  As the Corps completed detailed planning and engineering for the pilot project, the Coastal Conservancy enlisted the support of the Port of Oakland, local environmental organizations, labor organizations and maritime industries in seeking Congressional approval of the entire Sonoma Baylands salt marsh restoration project.  In late 1992, Congress directed the Corps of Engineers to construct the Sonoma Baylands Wetland Demonstration Project.  The Coastal Conservancy and the Port of Oakland provided 25% of the total project cost.   

As a result of initial planning and engineering work completed by the Coastal Conservancy and under the Coastal America program, the Corps of Engineers was able to award the first construction contract for the Sonoma Baylands project just one year after receiving funding for the project.  Within a few months of starting construction, 207,000 cubic yards of dredged material from the Petaluma River navigation channel were placed in the pilot unit.  During the next year, 1.7 million cubic yards of clean material from the deepening of Oakland Harbor were placed in the main unit.  Both units were opened to the tidal action of the Bay in 1996, beginning the process of natural marsh formation.  Construction of the project was completed  for about half of the total amount authorized by Congress.  The Sonoma Baylands project began attracting large numbers of shorebirds and waterfowl even before the restoration of tidal action.  The Corps and Coastal Conservancy are continuing to closely monitor the development of the marsh.  The tidal channels that connect the project to the open waters of the Bay have gradually expanded, increasing the range of tidal action and the amount of sediment deposition in the restoration area.  Salt marsh vegetation quickly colonized the entire perimeter of the restoration area and is gradually expanding further toward the center of the site as additional sediment is naturally deposited over the dredged material.  The site continues to provide a feeding and resting area for large numbers of shorebirds and waterfowl as development of the young marsh continues to progress.

The success of the Sonoma Baylands project has provided the basis for a continuing and productive partnership between the California State Coastal Conservancy and the U.S. Army Corps of Engineers.  The Conservancy, Corps and cooperating stakeholders are currently pursuing several other larger restoration projects in San Francisco Bay.