Which estuary in California is the largest in the state and a key habitat for salmon?

San Francisco Bay is California’s largest estuary and a key habitat for salmon.

The bay is part of a larger estuarine system linking San Francisco Bay, San Pablo Bay, Suisun Bay, and the Sacramento–San Joaquin River Delta. Rivers carry freshwater and nutrients into the system before it meets the Pacific Ocean through the Golden Gate.

Its shallow waters, mudflats, and remaining salt marshes provide nursery habitat for Pacific salmon, California halibut, Dungeness crab, and many other species. The bay also lies along the Pacific Flyway, making it an important stopover for millions of waterfowl.

A common mix-up is confusing San Francisco Bay with Puget Sound or Delaware Bay, both major coastal habitats but located outside California. The bay is also more than the water immediately beside San Francisco: its connected estuary stretches across a wide region surrounding Oakland, San Jose, and other Bay Area communities.