The San Pablo Bay National Wildlife Refuge lies along the north shore of San Pablo Bay in Sonoma, Solano, and Napa Counties in northern California. The refuge includes open bay/tidal marsh, mud flats, and seasonal and managed wetland habitats. The Napa-Sonoma marshes in San Pablo Bay have been greatly impacted by human activities such as hydraulic mining, salt production, water diversions, and diking, draining, and filling for agricultural and industrial uses. About 85 percent of the historic tidal marshes of San Pablo Bay have been altered, negatively affecting the ability of the remaining tidal marshes to accept winter rainfall and purify water in the bay. The refuge provides critical migratory and wintering habitat for shorebirds and waterfowl, particularly diving ducks, and provides year-round habitat for endangered, threatened, and sensitive species like the California clapper rail, salt marsh harvest mouse, California black rail, San Pablo song sparrow, and Suisun shrew. Numerous other threatened, endangered, and sensitive species require tidal marsh habitat for their survival, including 11 fish species that swim through San Pablo Bay to reach their fresh water spawning grounds.

Visitors should call for current directions to the refuge office. It is located 1/2 mile east of intersection of Lakeville Hwy on Hwy 37. The entrance to Lower Tubbs Island is located adjacent to Highway 37, approximately э mile east of the Highway 121/37 intersection in Sonoma County.