San Pablo Bay National Wildlife Refuge is a 13,190-acre protected wetland along the northern shore of San Pablo Bay in California, established in 1970 and extending from the mouth of the Petaluma River past Tolay Creek and Sonoma Creek to Mare Island. It preserves the largest remaining continuous expanse of pickleweed-dominated tidal marsh in the northern San Francisco Bay within a landscape of open water, mudflats, estuary, and wetlands. Part of a once vast Pacific Coast marsh system, this area survived major alteration from mining, salt production, diking, draining, filling, agriculture, and development. Today it is vital habitat for millions of migratory birds and sensitive species including the endangered Ridgway’s rail and salt marsh harvest mouse.