Lake Henshaw is a reservoir in San Diego County, California, at the southeast base of Palomar Mountain, approximately 70 miles (110 km) northeast of San Diego and 100 miles (160 km) southeast of Los Angeles.

[1] The lake covers approximately 1,140 acres (460 ha) and holds 55,000 acre-feet (68,000,000 m3) of water when full (lowered in 1978 from its original capacity of 203,581 acre-feet (251,113,000 m3) out of earthquake concerns),[2] in addition to groundwater stored in its local basin.

It drains an area of 207 square miles (540 km2) at the source of the San Luis Rey River.

The lake was constructed in 1923 (102 years ago) (1923) with the building of Henshaw Dam, an earth dam 123 feet (37 m) tall and 650 feet (200 m) long.

The lake features opportunities for catfish and carp fishing.