Blood, Trauma, and Biohazard Cleanup in Lake Mathews, CA

Lake Mathews is a rural census-designated place in western Riverside County, named for the large reservoir that lies just north of the community.

The Lake Mathews reservoir is the western terminus of the Colorado River Aqueduct, the endpoint of a 242-mile journey for water flowing from Lake Havasu on the Colorado River.

The dam across Cajalco Canyon was completed in 1939, the first Colorado River water arrived in February 1940, and deliveries to Southern California customers began in 1941.

Originally called the Cajalco Reservoir, the lake was renamed for W.B. Mathews, the attorney who helped create the Metropolitan Water District of Southern California and drafted the laws behind Hoover Dam.

A 1961 expansion that raised the dam and added two dikes nearly doubled the reservoir, bringing its capacity to 182,000 acre-feet.

Unlike most big Southern California lakes, Lake Mathews is completely closed to swimming, boating and fishing, to protect the drinking-water quality for the Metropolitan Water District's member agencies.

The Lake Mathews CDP is new in census terms — it first appeared in the 2010 census — and the 2020 census counted 5,972 residents there.

Lake Mathews households are exceptionally large: Census QuickFacts counts about 1,630 households averaging 4.00 people each, well above the national norm.

The community spreads across 15.9 square miles at an elevation of 1,775 feet on the northern end of the Temescal Mountains, a low-density, semi-rural corner of the Inland Empire.