Hollywood Reservoir, also known as Lake Hollywood, is a reservoir located in the Hollywood Hills neighborhood of Los Angeles, California, in the Santa Monica Mountains. It is maintained by the Los Angeles Department of Water and Power. The reservoir and surrounding neighborhood overlook the Hollywood Sign.
The reservoir is held by the Mulholland Dam, built in 1924. The dam was designed by William Mulholland as part of the Los Angeles Aqueduct storage system. The lake currently holds 2.5 billion US gallons (9,500,000 m3) of water and once provided Los Angeles with most of its water. It can be up to 183 feet (56 m) deep. Because of federal water quality legislation, the water department had plans to place tarps over the top of the lake to protect the drinking water from run-off and contamination. But, instead, due to neighborhood concerns and protests, two large underground water storage tanks that are 50 feet (15 m) deep and 200 feet (61 m) across were built on the north side of the reservoir, seen from above as two large circles next to each other. Also, after the 1928 dam burst of another Mulholland-designed dam (and a loss of life of some 600+ people), the City of Los Angeles dumped many tons of rock and fill on the outside edges of the dam as protection against any dam bursts.