Oyster Point and San Leandro Marina Watersheds
Located in San Leandro, the Oyster Point and San Leandro Marina watersheds drain a mix of small industrial areas and parkland near the San Francisco Bay shoreline.
The 1.2-square-mile Oyster Point Watershed drains the area east of Oakland International Airport and a former landfill that is now the Oyster Bay Regional Shoreline. Drainage is carried by underground culverts to an engineered channel that flows to Oyster Bay—named for the oyster farms that once existed just off shore.
Also 1.2 square miles, the San Leandro Marina Watershed is located south of Oyster Point and includes the marina, a public golf course, and Marina Park. The watershed is drained by two underground culverts that flow to a larger engineered channel and discharge near the marina.
Flora and Fauna
The Oyster Point and San Leandro Marina watersheds drain industrial areas, golf courses, and some parkland entirely through engineered channels and underground culverts. As a result, the watersheds support few plants and animals until they approach the bay. Oyster Bay Regional Shoreline is a former landfill that was converted to parkland in the 1980s. The conversion is an ongoing process that continues today. Clean soil was recently imported to plant mostly native trees and shrubs and turf for recreational purposes. A shoreline ecosystem is evolving that provides habitat for small mammals and shorebirds.
Large shell deposits off the East Bay and San Mateo shorelines in central San Francisco Bay provide evidence that oysters and other shellfish once thrived there. The oysters provided food for bat rays and shorebirds and were collected by Native Americans. European settlers supplemented the native oyster population with an Atlantic species when they began farming oysters in the 1890s, creating a successful industry. Oyster Bay was named for the oyster farms off the San Leandro shoreline. Water pollution and the filling of tidal flats and marshes to create land for airports, landfills, marinas, and the like led to the failure of the industry. By 1939, oysters either died from lack of oxygen or were unsafe to eat. Today Oyster Bay supports a limited population of shellfish, including non-native, native, and hybrid oyster species. Experimental oyster restoration projects are underway in several locations within San Francisco Bay.
Geology and Hydrology
Oyster Point and San Leandro Marina watersheds sit in the low-lying flatlands composed of soils laid down during the Holocene epoch by the large alluvial fans of San Leandro Creek to the north and San Lorenzo Creek to the south. With some small exceptions, the shoreline along this part of the bay is formed largely by artificial fill of mixed origins.
The San Leandro Marina is built on artificial fill with berms that encircle it to protect docked boats from wave activity and provide a small boating lagoon. By design, marinas limit flushing from tidal surge and strong currents that would otherwise disperse pollutants and bring in cleaner water. Where they are not dispersed, pollutants build up and degrade water quality. Typical pollutants in marinas come from illegal wastewater discharge from boats, urban runoff, and fuel. The limited tidal flushing and currents in marinas lead to sediment accumulation that requires regular dredging to keep marinas viable. Dredging, however, can stir up sediments where pollutants have settled. With so much potential for water quality impacts, marina design, discharges, and dredging activities are tightly regulated.