Hollywood Reservoir, also known as Lake Hollywood, is a reservoir located in the Santa Monica Mountains in the Hollywood Hills neighborhood of Los Angeles, California. It is maintained by the Los Angeles Department of Water and Power. The reservoir and surrounding neighborhood are overlooked by the Hollywood Sign.
The reservoir is created by the Mulholland Dam, built in 1924, designed by the Los Angeles Department of Water and Power, then named the Bureau of Water Works and Supply, as part of the city's water storage and supply system.
The lake has a capacity of 7900 acre-ft, which is 2.5 billion US gallons (9,500,000 m3) and a maximum water depth of 183 feet (56 m). After completion the reservoir level varied, though for most of the time it was kept a high level and was filled on several occasions. Within days after the collapse of the St. Francis Dam in March 1928, William Mulholland ordered the Hollywood Reservoir lowered due, in part, to public fears of a repeat disaster. Shortly after the disaster and in the years following, several engineering panels met to discuss the safety of the dam. These panels of engineers, from both the state and the LADWP came to differing conclusions. In 1931, the LADWP made the decision to permanently keep the Hollywood Reservoir lowered, and keep it to no more than 4,000 acre·ft (4,900,000 m3), the reservoir now is usually maintained at about 2,800 acre·ft (3,500,000 m3).