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About the Santa Ynez Reservoir
The Santa Ynez Reservoir is part of LADWP’s drinking water system and provides a regular supply of water for the Pacific Palisades community. The Santa Ynez Reservoir must be covered to protect treated water from contamination, per state and federal regulations.
LADWP maintains robust infrastructure to ensure a reliable source of drinking water for urban communities like the Palisades. LADWP’s system meets Fire Code requirements for fighting structure fires, but, like all municipal water systems, it is not designed to fight large-scale wildfires. For more information, see the Luskin Center for Innovation at UCLA’s summary on municipal water systems and firefighting: https://innovation.luskin.ucla.edu/water/local-water-resiliency/do-urban-water-supply-systems-put-out-wildfires/
Water Infrastructure Serving the Pacific Palisades Community
The main drinking water supply for the Pacific Palisades is transported via a large pipe called the Westgate Trunk Line. This trunk line, which measures up to 36 inches in diameter in most sections, supplies the lower elevation areas through pressure-regulating valves. Additional water from the trunk line is also pumped to, and stored in, three water tanks that serve higher elevation areas in the Palisades: the Marquez Knolls Tank, the Trailer Tank, and the Temescal Tank. Each tank has a capacity of about one million gallons and serves a different water pressure service zone in the Palisades community. The tanks meet or exceed requirements for firefighting needs under the Fire Code and for supplying drinking water to each of their corresponding service zones.
The Westgate Trunk Line terminates at the Santa Ynez Reservoir. If supply from the Westgate Trunk Line becomes unavailable, the Santa Ynez Reservoir could be used to supply water to the same community served by the trunk line.
Drinking Water Regulations Governing Drinking Water Reservoirs
State and federal drinking water regulations require that protective covers on treated water reservoirs remain in good condition to prevent contamination. If a hole or tear compromises this protective barrier, it must be repaired, which may require the reservoir to be taken out of service.
The Santa Ynez Reservoir uses a reinforced rubber floating cover that sits right on top of the water in the reservoir.
LADWP also operates open-air reservoirs that are not part of the drinking water system but are available for aerial firefighting and emergency supplies. In fact, they have been vital in protecting many neighborhoods during aerial firefighting operations. The Santa Ynez Reservoir is not an open-air reservoir.
Federal and State Fire Codes
LADWP’s water system serving the Pacific Palisades area and all of Los Angeles meets all federal and state fire code requirements for urban development and housing, even when reservoirs are temporarily offline.
While LADWP reservoirs, hydrants, pumping stations, and other infrastructure provide water for firefighting, it’s important to clarify that municipal water systems are not built to extinguish large scale wildfires.
Reservoirs Available for Aerial Firefighting Efforts
Over 8.5 billion gallons of water are available in LADWP’s non-drinking water, open-air reservoirs, including Hollywood, Lower Stone Canyon, and the Encino Reservoirs. LADWP’s
non-drinking water, open-air reservoirs are meant for helicopters to access from the air and are available for aerial firefighting efforts when the need arises, weather permitting. All three reservoirs were used to directly support aerial firefighting efforts in the January 2025 fires.
LADWP’s open-air Encino and Lower Stone Canyon Reservoirs, were accessed by firefighting aircraft, as the weather permitted, to help prevent the Palisades fire from spreading to nearby communities of Bel-Air, Encino, Tarzana and Mandeville Canyon during the January 2025 fires.
Because the Santa Ynez Reservoir is covered to protect the treated drinking water, it is not accessible to helicopters for aerial firefighting efforts. There is a helipad and a fire hydrant adjacent to Santa Ynez Reservoir where a helicopter can fill up water. This fire hydrant is not supplied by water from the Santa Ynez Reservoir but rather, is supplied with water from the general LADWP water system. Therefore, that hydrant’s functionality does not depend on Santa Ynez Reservoir being in service. Los Angeles Fire Department has informed LADWP that their helicopters used the helipad and hydrant at the Santa Ynez Reservoir on January 7, 2025, the first day of the Palisades Fire, until air operations ended at about 7:45pm that evening due to the weather.
2024-25 Santa Ynez Reservoir Repairs
A large tear in the floating cover required LADWP to take the reservoir offline in early 2024 for repairs to meet safe drinking water regulations. The tear allowed the water beneath the floating cover to be exposed to the environment and contaminants. The repairs were completed and the reservoir returned to service on June 25, 2025.
It is normal for reservoirs to go offline for inspections or repairs, and the system continues to be compliant with regulations during this time. This is a standard part of maintaining water quality and infrastructure safety. It would not be possible to keep all of LADWP reservoirs operational all the time. https://www.ladwpnews.com/ladwps-santa-ynez-reservoir-returns-to-service/
During any period of time when the Santa Ynez Reservoir is offline, the Pacific Palisades water system still complies with all fire codes and is built to meet regular and emergency demands. While the Pacific Palisades’ main water supply comes through the Westgate Trunk Line, the Santa Ynez Reservoir can provide backup as needed to the system. During the Palisades Fire, the trunk line remained fully operational. However, high demand caused a significant drop in water pressure.
Understanding Reservoir Capacity
It’s been reported that the capacity of the Santa Ynez Reservoir is 117 million gallons. The reservoir would not be filled to that amount. Like most covered reservoirs, the fill level of the Santa Ynez Reservoir varies and the reservoir operates within a limited range—there’s a maximum level it should not exceed and a minimum level it should stay above to remain functional. This range, known as the operational band, ensures the reservoir maintains water quality and system pressure. As a result, the capacity of 117 million gallons does not reflect how much water is in the reservoir, or actually available for use, which is only a fraction of the reservoir’s capacity.
Status of Fire Hydrants in the Pacific Palisades Before and During the Fire
LADWP works with LAFD, which is responsible for inspecting fire hydrants citywide. LADWP repaired every hydrant needing repairs as reported by LA Fire Department inspectors before the fire.
During the fire, water from the Westgate Trunk Line, which supplies the Palisades, was used at extraordinary rates. Firefighters used water from hydrants; residents turned on hoses and sprinklers when evacuating; and as structures burned damaged or opened premises pipes leaked water. This extraordinary demand led to a loss of water pressure. That lack of water pressure impacted the pumps used to fill the three water tanks that supply water to the higher elevations in the Palisades and the tanks ran out of water. As pumping stations lost pressure and the tanks ran empty, there were reports that some hydrants in the Palisades-especially those in high-elevation zones that are serviced by the tanks- lost pressure and water flow. Because hydrants do not have sensors, however, LADWP does not know exactly which hydrants lost pressure or when.
As soon as LADWP identified the risk of losing water in the tanks and water pressure in the system, we deployed potable water tankers to sustain support for firefighting efforts.
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