Diamond Valley Lake

Diamond Valley Lake is an artificial reservoir in Riverside County, California, covering more than 1,800 hectares of surface area and reaching depths of up to 79 meters (260 feet). The basin is enclosed by three large earth-fill dams and stores nearly a billion cubic meters of water for emergency use and regional supply.

Construction began in 1995 and took eight years until the basin was fully filled. The project became necessary to supply Southern California with drinking water for several months in case of drought or earthquake.

The name honors the valley's former agricultural use before the reservoir filled the basin. Visitors today see anglers along the shore and sailboats on the open water, while the visitor center displays fossils recovered during construction.

Visitors can hike, cycle and fish around the reservoir, with some shore areas accessible to the public. The easiest way to reach it is by car, as the site sits away from major towns.

The construction site uncovered remains of mammoths and mastodons, now on display at the nearby museum. Boats may only use electric motors to preserve water quality for drinking supply.