Back to Explore Watersheds

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  • Waterbodies
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  • Map

    The North Alameda and Southwest Alameda watersheds drain Alameda Island, which occupies most of the city of Alameda and is located across the Oakland Estuary from the city of Oakland. The 3.4-square-mile North Alameda Watershed covers the majority of the island, including the urbanized area in the north and the former Naval Air Station, now known as Alameda Point. This former Naval Station is now a mixed-use community of wetlands, grasslands, and commercial areas. The Southwest Alameda Watershed covers 1.03 square miles and includes the Southshore area, which is separated from the main section of the island by Alameda Lagoon. Both Alameda Point and Southshore are filled baylands and are relatively flat. Therefore, surface water is transported not by creeks but by a complex system of storm drains that empties into the estuary, San Leandro Bay, and San Francisco Bay–the water bodies that surround the island and the lagoons.

    North Alameda and Southwest Alameda Watersheds

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  •  Features

    Alameda Island, once a peninsula that connected the cities of Alameda and Oakland, is composed of wetlands, lagoons, and several artificial bodies of water. The Oakland Estuary, also known as the Oakland Inner Harbor, was originally San Antonio Creek, whose branches extended into Lake Merritt in downtown Oakland and the Brooklyn Basin. The peninsula became an island when a shipping lane known as the Tidal Canal was dredged in 1901, turning San Antonio Creek into the Oakland Estuary. Freshwater creeks are not a part of the natural landscape of Alameda Island due to its flat topography and porous sand.

    Flora and Fauna

    Several plant habitats can be found on Alameda Island: grassland, seasonal wetlands, and northern coastal salt marsh. Grassland communities support native grasses and wildflowers, though the majority are now nonnative grasses such as tall fescue, Bermuda grass, pampas grass, and cordgrass. Seasonal wetlands provide habitat for native plant species such as Monterey centaury, common nut sedge, and arroyo willow. Reptiles and amphibians such as the Western fence lizard have been observed in Alameda Point in addition to raptors like the northern harrier and white-tailed kite. Mammals in the watershed include the Virginia opossum, gray and red fox, California vole, raccoons, and skunks. Shorebirds, both migratory and residential, nest on the island as well; these include the endangered California least tern. A population of green sturgeon, which is a federally threatened species and California species of special concern, has been found in the waters designated as essential fish habitat near the island. To find out more, see the Alameda Point Environmental Impact Report.

    Geology and Hydrology

    Alameda Island is a sand dune that formed during the last ice age over 10,000 years ago. Its porous soils allow rainwater to soak in, hence there are no natural creeks on the island. It was originally a low lying peninsula whose sand, known as the Merritt Sand, was deposited during or shortly after the last ice age when sea levels were low and San Francisco Bay was a wide river valley. When the sea level rose, the tops of the dunes remained. Areas of the peninsula that were on higher ground once harbored one of the largest coastal oak forests in the world. (Alameda is Spanish for grove of poplar trees or tree-lined avenue.) Alameda is the largest island in San Francisco Bay. Its area doubled in the 1850s when artificial bay fill from mining debris and dredging for shipping channels was used to fill many of the marshlands and tidal flats of the bay. On Alameda Island, bay fill was composed mainly of Merritt sand, bay mud, Temescal formation debris, broken rock, and miscellaneous refuse.

    The average annual precipitation in Alameda is 20.81 inches. Groundwater in the area occurs at shallow depths and at the surface, taking on a brackish quality as it mixes with the saline waters from San Francisco Bay. Central Avenue stretches from one end of the island to the other and serves as a loose point of reference for its spine. The avenue also divides North Alameda Watershed from Southwest Alameda Watershed. Municipal storm drains carry surface runoff into a system of underground culverts that empty into the surrounding bodies of water.

    Major Issues

    Storm water conveyance, flooding, global sea level rise, littering, nonnative plant species, shoreline erosion, and trash hot spots due to the tides are the main environmental challenges. The city is mandated to conduct annual cleanups at four trash hot spots subject to tidal accumulation.

  • Major Creeks & Waterbodies

    North Alameda Watershed

    A system of storm drains and underground culverts drains the northern side of Alameda Island into the Oakland Inner Harbor or estuary.

    Oakland Estuary

    The Oakland Estuary is a strait that separates the cities of Oakland and Alameda, its eastern end connecting to San Leandro Bay and its western end to San Francisco Bay. U.S. Coast Survey maps from the 1850s label this arm of the bay San Antonio Creek. Since that time, dredging and manufacturing industries have caused much sedimentation and contamination.

    Runway Wetland

    Runway Wetland was originally tideland characterized by open water during high tide and mud flats during low tide. The land was filled to make the runways, roads, and sea wall for the Naval Air Station Alameda. San Francisco Bay water that enters through the seawall, as well as precipitation and surface runoff, has created a shallow marsh with tidal marsh vegetation. Roughly 16.5 acres, the wetland is dominated by pickleweed and saltgrass as well as nonnative plant species such as iceplant. This artificial wetland is located at the southern edge of Alameda Point and is separated from San Francisco Bay by the seawall.

    San Francisco Bay

    San Francisco Bay is a shallow and productive bay and estuary. Since the mid-19th century, up to one-third of the original bay has been built upon or filled in using dredging material from the bay and excess soil from development projects. Only about 20 percent of the original tidal marshes that ringed the bay remain today.

    West Wetland

    West Wetland is an artificial wetland on Alameda Point that includes 32.4 acres of shallow ponds and vegetated salt marsh. The dominant plant species are pickleweed and saltgrass. The higher areas are susceptible to invasive plant species such as iceplant, cranesbill, ox-tongue, and coyote brush.

    Southwest Alameda Watershed

    A small network of underground culverts and storm drains empties into San Francisco Bay.

    Alameda Lagoon

    Alameda Lagoon is located on Alameda Island and is about four miles in length. Totally artificial, the lagoon separates the natural land of Alameda from areas of artificial fill created in the 1950s and thus marks the original shoreline. Alameda Lagoon is subdivided into five separate but interconnected lagoons. Filled with salt water from San Francisco Bay, the lagoon supports a variety of wildlife including egrets, cranes, night herons, blue herons, terns, coots, cormorants, many varieties of ducks (resident and migratory), and visiting geese. The lagoon waters are owned by the Alameda West Lagoon Home Owner’s Association (AWLHOA), and maintenance is shared equally with the City of Alameda through its Public Works Department.

    San Leandro Bay

    San Leandro Bay is an arm of San Francisco Bay, located along the east side of the Oakland International Airport and Bay Farm Island. Once a rich habitat for wildlife, most its original marshland and habitat have been filled or dredged, with the exception of Doolittle Pond and Arrowhead Marsh (City of Oakland).

  • Recreational Opportunities

    The North Alameda and Southwest Alameda watersheds offer recreational opportunities that can satisfy a variety of interests including wind surfing, walking, running, cycling, and swimming. Municipal and regional parks are scattered throughout the island, and beaches skirt the rim.

    North Alameda Watershed Trails

    Alameda Point is the former Alameda Naval Air Station on the western end of Alameda Island. It is currently in the process of being transferred from the U.S. Navy to the City of Alameda for future development that would include a strong commercial base with open space, recreational, residential, and retail uses. On June 4, 2013, the city took title to about 1,400 acres of land and water from the Navy. Over 700 acres of parks and open space will be preserved at Alameda Point, and a Bay Trail extension is planned around the shoreline to connect new parks.

    Encinal Trail

    The Encinal Trail is a paved path located on Encinal Beach near Encinal High School. The approximately half-mile-long trail is managed by the East Bay Regional Park District as part of the Alameda Point Shoreline/San Francisco Bay Trail. Visitors can stroll or bike along the shoreline from Encinal Boat Ramp Park to the USS Hornet, a World War II aircraft carrier, while taking in the panoramic views of San Francisco Bay.

    Southwest Alameda Watershed Trails

    McKay Avenue Staging Area

    There are two main entrances into Robert W. Crown Memorial State Beach. The McKay Avenue Staging Area is the closest trailhead to Crab Cove Visitor Center and the access point for visiting the tide pools in the Crab Cove Protected Area. Follow the trail as it connects to the bicycle and hiking trail that parallels Shoreline Drive.

    Otis Drive Park Entrance

    The Otis Drive park entrance is the other main trailhead into Robert W. Crown Memorial State Beach. A bicycle and hiking trail follows Shoreline Drive, extending to the eastern end of the beach. This paved path offers beautiful views of San Francisco Bay.

    Pedestrian/Bike Bridge and Water Walk

    A pedestrian/bike bridge connects Alameda with adjacent Bay Farm Island. It is located next to the Aeolian Yacht Club at 980 Fernside Boulevard. Visitors can enjoy this casual walk over the bridge and take in views of San Francisco Bay.

    North Alameda Watershed Parks and Recreation

    For a list of municipal parks on Alameda Island, please see the Parks & Facilities section of the City of Alameda website.

    Alameda National Wildlife Reserve

    The Golden Gate Audubon Society is working to have 575 acres of land and 390 acres of adjacent bay waters transferred from the U.S. Navy to the U.S. Fish & Wildlife Service to create the Alameda National Wildlife Reserve, also known as the Nature Reserve. However, until the transfer has been completed, public access will continue to be limited to special events. This area is the most northern breeding ground of the California least tern.

    Encinal Beach

    Encinal Beach is a saltwater beach near Encinal High School. It is monitored for bacteria by the East Bay Regional Park District in cooperation with the Alameda County Environmental Health Department. Visitors are advised to observe Water Quality Stop Light designations before swimming in these bay waters. The beach provides access to Encinal Boat Ramp Park.

    Encinal Boat Ramp Park

    Operated by the City of Alameda, Encinal Boat Ramp Park provides access to a new section of the Bay Trail, known as the Encinal Trail. The park also has picnic benches, restrooms, easy parking, and beautiful views of the bay, in addition to the boat ramp.

    Point Park

    Point Park is a proposed 147-acre regional park in the northwestern part of Alameda Point. No plans for funding, building, or operations have been made, but possible amenities include 20 acres of seasonal wetlands, a section of the Bay Trail, grasses covering 45 percent of the park area, and group and family picnic areas.

    Shoreline Park

    Shoreline Park, not to be confused with a park with the same name on Bay Farm Island, is located on the estuary and can be accessed from Marina Village Plaza or the Pacific Marina. It is a quiet, short parkway strip along the city waterfront. A segment of the Bay Trail offers pedestrians and bicyclists views of the marina and estuary. Other amenities include lawns, a parcourse, parking, and commercial establishments. There is also a private freshwater lagoon system along the back side of Shoreline Park.

    Southwest Alameda Watershed Parks and Recreation

    For a list of municipal parks on Alameda Island, please see the Parks & Facilities section of the City of Alameda website.

    Crab Cove Visitor Center

    Crab Cove Visitor Center is part of Crown Memorial State Beach. Built in 1979, it features an 800-gallon aquarium and interpretive panels to educate the public about the history of Crab Cove and its unique mud flat and rocky shore ecosystems. Crab Cove was designated in 1980 as the first California estuary marine reserve; as such, all plant and animal life is protected. The Visitor Center offers naturalist-guided programs and special events such as an annual sand castle building contest and concerts.

    Crown Memorial State Beach

    Crown Memorial State Beach is located at Eighth Street and Otis Drive. It is part of the East Bay Regional Park District and operated by agreement with the state and city. The largest beach on the San Francisco Bay, it offers 2.5 miles of sand with a bicycle trail bordered by sand dunes. Visitors can enjoy its warm and shallow waters year round during park hours. They can also rent sailboards and kayaks and bring car-top inflatables. Other activities include birding, fishing, kite boarding, windsurfing, hiking, and bicycling. The city, in collaboration with the regional park district, conducts an annual coastal cleanup event along Crown Beach. Other destinations within the park include the Elsie Roemer Bird Sanctuary to the east and Crab Cove to the north.

  • Restoration Efforts

    Ongoing restoration projects in these watersheds serve to preserve and enhance the environment through invasive plant removal, shoreline recreational opportunities, and erosion control. The City of Alameda, in conjunction with the California Coastal Conservancy, is removing cordgrass along the estuary, San Leandro Bay, and Crown Memorial Regional Shoreline. The Crown Memorial State Beach Sand Project has brought in 82,600 cubic yards of sand for erosion control. Information about other restoration projects can be found on the City of Alameda website and on the California Department of Fish and Wildlife website.

  • Get Involved

    There are several organizations involved in restoration efforts, litter removal, and educational programs. The East Bay Regional Park District, in partnership with the City of Alameda Parks and Recreation, the YMCA, and the Boys and Girls Club, will implement the Fishing Outreach Program in 2014 for youth and adults. This program will focus on shoreline and bay fishing and complement EBRPD’s ongoing inland freshwater fishing programs.