A large reservoir in Pacific Palisades that is part of the Los Angeles water supply system was out of use when a ferocious wildfire destroyed thousands of homes and other structures nearby.
Officials told The Times that the Santa Ynez Reservoir had been closed for repairs to its cover, leaving a 117 million gallon water storage complex empty in the heart of the Palisades.
The revelation comes among growing questions about why firefighters ran out of water while battling the blaze. Numerous fire hydrants in higher-elevation streets of the Palisades went dry, leaving firefighters struggling with low water pressure as they combated the flames.
Department of Water and Power officials have said that demand for water during an unprecedented fire made it impossible to maintain any pressure to hydrants at high elevations.
Had the reservoir been operable, it would have extended water pressure in the Palisades on Tuesday night, said former DWP general manager Martin Adams, an expert on the city’s water system. But only for a time.
“You still would have ended up with serious drops in pressure,” Adams said in an interview Thursday. “Would Santa Ynez [Reservoir] have helped? Yes, to some extent. Would it have saved the day? I don’t think so.”
A DWP official acknowledged that the reservoir’s absence likely contributed to some diminished pressure and dry hydrants in upper regions of the Palisades.
However, a spokesperson for the utility said in a statement that DWP was still evaluating the effect of the reservoir being placed offline, and that staffers were conducting a root-cause analysis.
“Our primary focus is to provide water supply throughout the city,” the DWP spokesperson said, adding, “The system was never designed for a wildfire scenario that we are experiencing.”
It’s unclear when the reservoir first went offline. Adams said it had been out of service “for a while” due to a tear in the cover and that DWP’s vast storage and supply infrastructure still provided water to residents without disruptions, until this week.
Water pressure in the upper Palisades is sustained with three storage tanks, which hold 1 million gallons each. The tanks, part of a network of more than 100 across the city, are located at successively higher elevations in the coastal, hilly neighborhood, with water pumped up to the tanks, then flowing down by gravity to maintain pressure.
By 3 a.m. Wednesday, all three tanks had gone dry.
DWP Chief Executive Officer Janisse Quiñones said the tanks could not be refilled fast enough and that demand at lower elevations hampered the ability to pump water to tanks at higher elevations. In one case, DWP crews attempting to reroute water to refill a tank had to be evacuated, officials said.
Quiñones said four times the usual demand for water on the trunk line over a 15-hour period led to drops in water pressure.
Had the Santa Ynez Reservoir been in use in that period, Adams estimated, that demand might have been three times as high. Water in the reservoir would have fed the firefighting equipment and helped the pump stations push water to the storage tanks. But the reservoir “wouldn’t have lasted forever and would not have been a fix-all,” Adams said.
“Eventually, you would have gotten to the same place,” he added. Adams cautioned that he was basing his assertion on a rough estimate, and that he had not calculated the specific impact.
Whether the reservoir would have had a meaningful impact on fighting a blaze of such intensity remains unclear. Researchers said urban water systems like DWP’s were not designed to fight wildfires that overtake whole neighborhoods.
The National Weather Service had warned of “life threatening” winds before the fire broke out. By then, Adams said, the DWP’s options were limited. He noted that fire risk is not exclusive to the Palisades but is present across L.A. County.
Had DWP held water in the reservoir with a ripped cover, the water would have been legally undrinkable except in emergencies.
And had the utility opted to start filling the reservoir over the weekend, in advance of the extreme winds, Adams said it was unclear whether the water could have been added fast enough to be useful.
“They would have been betting that there would be a fire that wipes out the whole neighborhood, which of course, no one has ever seen before,” he said. “It would have been a strange bet.”
The reservoir is one of several operated by DWP across the city, which have a combined capacity of more than 4.1 billion gallons of water. Including aqueduct reservoirs, the city can store more than 91 billion gallons across its vast infrastructure. The Santa Ynez complex, at 117 million gallons, is among several sources of water in the area, including a large pipeline from Stone Canyon and a smaller site, the nearby Palisades Reservoir.
The utility designs the system with redundancies and multiple sources of water. In a statement, the agency said that none of its infrastructural assets failed Tuesday and early Wednesday but that the “intensity” of the fire disrupted the contingencies in place.
Joseph Ramallo, a chief communications officer for DWP, said the reservoir was scheduled to reopen in February. The maintenance, he said, was needed to comply with water quality regulations.
Adams said that if the Santa Ynez Reservoir had been in normal use with a fully repaired cover, the water level would likely have been well below maximum capacity.
In the winter, water levels are kept purposely lower because of a seasonal decline in water use by residents. If water remains stagnant in a reservoir, there is a risk that the disinfectant, chloramine, will break down and chlorine will evaporate, leaving behind ammonia that could foster bacterial growth in the water supply.
“You would not have had a whole pile of water just sitting there,” Adams said. “That’s the battle in water storage — you’ve got to keep your tanks and reservoirs fluctuating.”
Furious residents have pointed to the lack of water pressure as one factor contributing to the destruction of 5,300 homes and buildings in L.A., Santa Monica and Malibu. Civic leaders like L.A. City Councilmember Traci Park and developer Rick Caruso have pointed to the issue as a sign of poor infrastructure upkeep.
