Stone Canyon Reservoir
Stone Canyon Reservoir and its nearby Upper Stone Canyon Reservoir are two connected water storage basins in the Westside of Los Angeles, inside the Bel Air neighborhood near Mulholland Drive. Located in the Santa Monica Mountains, they sit roughly 850 feet above sea level. The larger lower reservoir and the smaller upper reservoir work together to supply water to the Westside, serving about 400,000 people in areas like Pacific Palisades, the Santa Monica Mountains, and West Los Angeles. They are owned by the Los Angeles Department of Water and Power (LADWP).
The main lower reservoir is the bigger basin, with the upper reservoir just to the north. Both were built by LADWP’s water division, originally completed in the 1920s. The early design used an earth-fill dam made with hydraulic sluicing, a method developed by William Mulholland. The original capacity was about 8,000 acre-feet. In the mid-1950s, the upstream dam was rebuilt with more modern materials while the lower part remained largely the same. The dam stands about 160 feet high.
Originally, the reservoirs stored treated drinking water and collected runoff that could cause contamination. A water treatment plant was added downstream in the early 1950s. By the early 1990s, tests showed water quality problems, including high turbidity, bacteria, and algae, which led to upgrades and new treatment facilities.
Starting in 2004 and finishing in 2007, LADWP built a new membrane filtration and pumping facility to treat surface water more effectively. A large bypass pipeline helps move treated water directly to customers, improving reliability and safety. Because of these changes, the Lower Stone Canyon Reservoir is no longer used for regular water supply, except in emergencies, while the Upper Reservoir remains part of the system. In recent years, there have been plans to replace the Upper Reservoir with underground storage and to expand surrounding recreation and landscaping, but for now the site focuses on water treatment and safety.
The Lower Reservoir area is also part of LA’s security upgrades for its water system carried out after 9/11. The two reservoirs can be affected by heavy rains and floods, and water from the Upper Reservoir is directed through the filtration system before reaching customers.
Stone Canyon Reservoir is not open for public recreation. There is no fishing, sailing, or swimming. However, the area is known for the Stone Canyon Overlook on Mulholland Drive, opened in 1994 as a scenic view of the canyon. The site has appeared in films and books, and nearby Mulholland Drive is famous for its scenic routes through the mountains and reservoirs.
This page was last edited on 3 February 2026, at 11:16 (CET).