Northern Harrier and Sweetwater Marsh
Northern Harrier and Sweetwater Marsh
Credit: WildTech

US Fish and Wildlife ServiceSan Diego National Wildlife Refuges

Member Since: 10/01/2001

Primary Contact: Lisa Cox
Other Contact: Andrew Yuen

1080 Gunpowder Point
Chula Vista, CA 91910
619-476-9150 ext. 106

Tijuana Slough 1,072 acres Sweetwater Marsh ,316 acres South San Diego Bay Unit, Approved acquisition boundary, 3,927; current management authority, 3, 258 San Diego NWR and Vernal Pools Stewardship Project, approved acquisition boundary 52,000

Partner Information: Chula Vista Nature Center

Site Tour | Site Link


The four refuges of the San Diego National Wildlife Refuge Complex are part of the 92 million acre National Wildlife Refuge System. The refuges of the San Diego Complex were established to conserve and protect the rare birds of southern California's coastal marshes, and to support San Diego's landscape-wide effort to preserve the rich biological diversity for which the region is famous. Each of our refuges is designated as a Globally Important Bird Area and the South San Diego Bay refuge as a Western Hemisphere Shorebird Reserve Site of National Importance. San Diego County is now home to more federally listed threatened and endangered species than any other county in the continental United States.

The Coastal Refuges

Tijuana Slough NWR lies at the southern terminus of the United States at the U.S./Mexico border and is southern California's only coastal estuary not bisected by roads or rail lines. Its habitats include open water, tidal salt marsh, beach dune, riparian, vernal pool and upland surrounded by residential neighborhoods. Over 370 species of birds have been recorded on the refuge. Tijuana Slough is part of the National Oceanic and Atmospheric Administration's Estuarine Reserve System, and designated as a RAMSAR Wetland of International Importance.

The San Diego Bay National Wildlife Refuge has two sub-units. The Sweetwater Marsh Unit is located on the east side of San Diego Bay in the cities of Chula Vista and National City. The Refuge is comprised of 316 acres of salt marsh and coastal uplands along the Pacific Flyway. The Chula Vista Nature Center, owned and operated by the City of Chula Vista, has museum designation and offers visitors opportunities for education, wildlife interpretation and viewing and limited hiking trails on the refuge.
The South San Diego Bay Unit lies between Tijuana Slough and the Sweetwater Marsh Unit. It was dedicated in June of 1999 to ensure that thousands of shorebirds and waterfowl migrating along the Pacific Flyway, as well as the Bay's resident species, will survive into the next century. This unit supports numerous endangered and threatened species and is a vital link to other wildlife areas.

Like its sister coastal refuges, the Seal Beach NWR was established to protect endangered species. It is located on the Seal Beach Naval Weapons Station, one of many partnerships between the U.S. Fish and Wildlife Service and the Department of the Navy.

The Inland Refuge

San Diego NWR
Mountains, grassland, oak woodland, freshwater marsh, and cool riverine corridors run through coastal sage and chaparral at the Otay-Sweetwater Unit of this refuge. In a wet springtime, there are fields of wildflowers. This refuge is not officially open at present but is the National Wildlife Refuge System's contribution to the Multiple Species Conservation Plan, a program designed to conserve open space and species survival while allowing appropriate development.

Vernal Pools Stewardship Program: Vernal Pools are an extremely rare habitat type that come to life with the onset of winter rains. In late summer, fall and early winter, vernal pools appear as dry, dusty indentations mostly devoid of vegetation. Then, in late winter, a spectacular transformation occurs as these depressions fill with water. High numbers of endangered, rare and sensitive species of plants and animals appear. Vernal pools are often managed in partnership with other agencies, and most are not open to the public.


mixed coastal and chapparal types

Endangered salt marsh bird's beak, rare Yerba reuma, pickelweed, cordgrass and other salt marsh and upland plants such as California encelia, flat-top buckwheat, lemonadeberry, and many others. Inland, an entire array of coastal chaparral and sage scrub occur.

Light-footed clapper rail, California least tern, Belding's savannah sparrow, southwest willow flycatcher, western snowy plover, san diego horned lizard quino checkerspost butterfly, migrating and resident shorebirds, seabirds and waterfowl. Six species of tern, Western and eared grebes, black skimmers, black-necked stilts, rafts of brandt, coot, and migrating ducks are yearly residents.


The Kumeyaay Native American population lived and managed land in this area for hundreds of years. They left pot shards, “metates” or grinding stones, pieces of obsidian traded in far off lands, and other remnants sprinkled across San Diego' refuges, from the coast to inland. Today, Kumeyaay residents continue to be active members of the San Diego community. Kumeyaay who live just across the border in Mexico frequently visit relatives and neighbors for social, cultural and business activities. Kumeyaay groups offer cultural programs and support many community activities throughout the year.

Euro-American History

The wetland refuges of San Diego were used for farming, salt production, fishing, trash dumps and a myriad of other uses. On Sweetwater Marsh, a kelp production factory, built in 1916, employed 1500 people to make the components of gunpowder. After World War I, the San Diego Oil Products Corporation took over the plant. It was the largest cottonseed warehouse in the United States and cottonseed oil was stored at the facility. Later, the area was used for agriculture and, just prior to its establishment as a national wildlife refuge, the marsh and uplands were used as an illegal dumping ground.

Current Communities

Enclosed as they are by human populations, these urban refuges face a variety of challenges to wildlife. Refuge staff must manage not only for the traditional concerns of habitat conservation, but for a host of other impacts generated by everyday human activity. These include the invasion of exotic species that threaten to overwhelm native communities, domestic as well as feral cats and dogs that prey upon ground nesting birds and small mammals, and urban run-off from surrounding city streets.

The administrative headquarters for the San Diego NWR Complex is located on the Sweetwater Marsh Unit of the San Diego Bay NWR, and adjacent to the Chula Vista Nature Center. It is located at 1080 Gunpowder Point Drive, Chula Vista, CA 91910. The visitor contact station for the Tijuana Slough NWR is located at 301 Caspian Way, Imperial Beach, CA 91932. The Seal Beach NWR visitor center is located within the Naval Weapons Training Base and Refuge property at 800 Seal Beach Blvd. Seal Beach, CA. There is no visitor center (yet!) for the San Diego NWR.

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