Mendenhall Springs is an unincorporated community

Unincorporated area

In law, an unincorporated area is a region of land that is not a part of any municipality.To "incorporate" in this context means to form a municipal corporation, a city, town, or village with its own government. An unincorporated community is usually not subject to or taxed by a municipal government...

 in Alameda County

Alameda County, California

Alameda County is a county in the U.S. state of California. It occupies most of the East Bay region of the San Francisco Bay Area. As of the 2010 census it had a population of 1,510,271, making it the 7th most populous county in the state...

, California

California

California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

. It is located 9 miles (14 km) southeast of Livermore

Livermore, California

Livermore is a city in Alameda County. The population as of 2010 was 80,968. Livermore is located on the eastern edge of California's San Francisco Bay Area....

, at an elevation of 1818 feet (554 m).

William M. Mendenhall established a health spa here in the 1870s, which by 1909 had accommodations for 75 people, from springs that had been diverted through tunnels originally bored for gold prospecting.