Lake Matthews

Lake Mathews is a large reservoir in Riverside County, California, located in the Cajalco Canyon in the foothills of the Temescal Mountains. It is the western terminus for the Colorado River Aqueduct that provides much of the water used by the cities and water districts of the Metropolitan Water District of Southern California. The reservoir is fenced and closed to all public access. The lake is near the Riverside community of Lake Hills, and is skirted by Cajalco Road on the south, El Sobrante Road on the north and east, and La Sierra Avenue on the west. La Sierra Avenue traverses the top of the west dike. These roads are often used by commuters as a shortcut between Interstate 15 and Interstate 215 or California 91.

The reservoir was constructed by building a large earthfill dam across the northern side of the basin. Two smaller dams, called dikes, were built during the 1961 expansion to increase the lake's capacity.