San Joaquin Wildlife Sanctuary, Protected wetlands in Orange County, California.

The San Joaquin Wildlife Sanctuary is a protected wetland and freshwater marsh area located in Irvine, in Orange County, California. A network of walking paths crosses the grounds, connecting several distinct habitats that support native plants and wildlife.

The Irvine Ranch Water District owns the site, which was farmland in the 1950s and 1960s and later served as a duck hunting range. Wetland restoration began in 1988 and was completed in 2000. The Duck Club building, moved here in the 1940s, housed two hunting clubs until 1988.

The Duck Club, moved here in the 1940s, housed two hunting clubs until 1988 and now serves as a free meeting space for non-profit groups. The Audubon Society keeps a chapter office in the former bunkhouse. Monthly censuses have recorded over 120 bird species, among them herons, egrets, pelicans, sandpipers, kingfishers, roadrunners and hummingbirds.

The sanctuary is open to the public daily during the daytime, with free parking, restrooms, benches and trail maps at the site. Over 10 miles (16 km) of trails are wheelchair-accessible. The Duck Club building serves as a free meeting facility for non-profit organizations.

The wetland acts as a natural water treatment system, where bulrush plants filter excess nitrogen from the water through their roots before it flows into the nearby bay. This means the plants themselves are doing work that would otherwise require mechanical infrastructure.