The San Luis Refuge in the San Joaquin Valley of central California is one of the last remnants of the historically bountiful wintering grounds for migratory waterfowl of the Pacific Flyway. Located in the Bear Creek, Salt Slough, and San Joaquin River floodplain, it hosts a myriad of tree-lined channels and oxbows, wetlands and native grasslands. Thousands of acres of wetlands, fed by an intricate set of canals, are managed to produce natural food supplies for migratory waterfowl. San Luis also contains the most extensive network of pristine native grasslands, shrubs, and vernal pools that still remain within the Central Valley. Thousands upon thousands of mallard, pintail, green-winged teal, and ring-necked ducks flock into the managed wetlands; while the colorful, yet secretive, wood duck lives throughout the tree-lined slough channels. Herons and egrets nest in majestic oaks and willows, then feed on the refuge's abundant frog and crayfish populations. A wide diversity of songbirds, hawks, and owls also use refuge habitat.

San Luis Refuge is approximately 10 miles north of Los Banos, California. From Highway 152 in Los Banos, take Highway 165 (Mercey Springs Road) north 8 miles, then northeast 2 miles on Wolfsen Road to the refuge. The Kesterson Unit's public access point can be reached by driving 4 miles east of Gustine on Highway 140.