Emeryville Crescent State Marine Reserve, Marine reserve in San Francisco Bay, United States.

Emeryville Crescent State Marine Reserve is a protected area covering more than 100 acres of salt marshes and mudflats along the eastern shore of San Francisco Bay between Oakland and Emeryville. The waters and wetlands support diverse plant and animal species adapted to this coastal environment.

The area gained protection in 1985 as a turning point from industrial use to environmental conservation in the bay region. This designation helped preserve one of the few remaining natural shorelines of the bay.

Local fishers and dog-walkers use the marsh as a recreation area, and the reserve is also known for unauthorized camping, petty littering and dumping of large items such as TVs and refrigerators. Temescal Creek enters the wetlands near the Emeryville–Oakland border.

Access to the reserve is available through Powell Street in Emeryville, where visitors can use designated paths and observation points. Wear comfortable shoes suitable for wet conditions, as terrain varies with the seasons and weather.

The marsh is named for its crescent shape, curving from the Bay Bridge approach in Oakland to the foot of Powell Street in Emeryville. Its native pickleweed is being displaced by Spartina cordgrass, a non-native grass that has invaded 2.4 acres, or 2.5%, of the wetlands; an abatement program uses aquatic herbicides.