Lake Mathews - Riverside County, California

On 1/2/18 during a visit to proctor examinations for work I visited the Riverside area of South California.  I visited several lakes in the area.  This picture was taken on the southwest corner of the lake on the dam.  I startled a coyote that was resting against the dam wall when I walked up to take a picture.  Can you find him in the second photo?  Lake Mathews is a large 2,750 acre reservoir at the elevation of 1,391 feet in Riverside County, California is 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.

Originally named the Cajalco Reservoir, the reservoir is now named after W.B. Mathews, an attorney who was a key architect of the MWD and its business relationships with member water agencies. Construction on the reservoir began in 1933, at the same time the aqueduct was being built across the desert. The reservoir site had previously been occupied chiefly by carob orchards and tin mines. Lawrence Holmes, Sr., who owned 1,100 acres in the future reservoir basin, lost his property to eminent domain in a lengthy court battle.  The dam across Cajalco Canyon and its intake structure were completed in 1939. The first water arrived from the Colorado River in February 1940, and water deliveries began in 1941. In 1961, the reservoir’s capacity was nearly doubled to its current capacity of 182,000 acre-feet.

Lake Mathews is surrounded by approximately 4,000 acres of protected land. In 1982, this land was declared a State ecological reserve. In the early 1990s, an additional 9,000 acres was added to the reserve after the discovery of the endangered Stephens kangaroo rat in the area. The area is now called the Lake Mathews Estelle Mountain Reserve.

Lake Mathews was constructed in a basin formerly traversed by Cajalco Creek; thus, any water flowing down the creek enters the reservoir. Cajalco Creek is a tributary of the Santa Ana River via Cajalco Canyon Creek into Temescal Creek.
Since its dedication in 1940, the reservoir has been fenced off and closed to public access, supposedly to preserve water quality. The MWD has always been concerned about water quality and prohibits body contact sports like swimming in its other nearby reservoirs that are open for recreation, Lake Skinner and Diamond Valley Lake. Mathews is of greatest importance as its outlet feeds directly into pipelines that connect to member water agencies serving 8.4 million people.