Description - Once a 40,000-acre expanse of tidal marshes and free-flowing sloughs, the Napa-Sonoma marsh has been greatly impacted by human uses. The refuge was established to protect and manage some of the last remaining wetlands in the San Francisco Bay area.
- San Pablo Bay NWR, established in 1974, has over 13,190 acres of estuarine habitat including uplands, open bay, salt marshes, mud flats, freshwater wetlands, and agricultural lands that are being restored to wetlands. Once a 40,000-acre expanse of tidal marshes and free-flowing sloughs, the Napa-Sonoma marsh complex has been greatly impacted by human uses. Activities including hydraulic mining, diking and filling of marshes, water diversions, agricultural and industrial uses have resulted in a loss of almost 95% of San Pablo Bay's tidal marshes.
The refuge provides major migratory and wintering habitat for shorebirds and waterfowl, particularly diving ducks. The intertidal mud flats and seasonal wetlands of the refuge help support the almost one million shorebirds that winter and migrate through the San Francisco Bay area. Large numbers of scaup and canvasbacks are drawn to the open bay to feed on clams, mussels, fish and worms.
Numerous endangered, threatened and sensitive species require the tidal marshes along the edge of San Pablo Bay for survival. The endangered California clapper rail and salt marsh harvest mouse are found only in the tidal marshes of San Francisco Bay. Eleven anadromous fish species, including striped bass, surfperch, sturgeon, starry flounder, leopard shark, topsmelt, and anchovy spawn in the Sacramento-San Joaquin river systems that travel through San Pablo Bay as they enter and leave the drainages. Species of concern include the California black rail, San Pablo song sparrow, and Suisun shrew.
Recreation - Recreation activities include wildlife observation, study, and photography. Peak season for most species of shorebird, waterfowl and raptors is September through March. Summer visitors will see gulls, American avocets and black-necked stilts, as well as pelicans, herons, and egrets. Harbor seals may be visible throughout the year. There are occasional interpretive tours and trails along the edge of the bay. Saltwater fishing and waterfowl hunting are by boat access only. Pheasant hunting is permitted in the Tolay Creek flood plain during approved seasons. Fishing and hunting are governed by federal and state regulations. Boating is another excellent way to view wildlife, although canoeists and small craft users should be aware of tides and rapidly changing weather. There is also an environmental education program: "In the Marsh at Mare Island" for those who are interested.
Pets, camping, and campfires are not permitted on the refuge.
Climate - The climate is Mediterranean, so it tends to be windy and cold. The best weather is in spring and fall. From February through July, mild weather carpets the land. Summer is the time when fog can blanket the coastal areas, while the inland valleys remain warm. The best advice is to dress in layers.
The refuge is located along the northern edge of San Pablo Bay between Vallejo and the Petaluma River. To get there, take either Highway 101 of Interstate 80 to Highway 37, and follow 37 to 1/4 mile east of Highway 121. The public access gate is on the south shoulder of Highway 37; walk in from there, along the east bank of Tolay Creek.
Visitors should call (510) 792-0222 for current directions to the refuge office on Mare Island.