PWD Water supply Littlerock Dam

Photo courtesy of Carey Louey/Palmdale Water District

Littlerock Dam, one of the Palmdale Water District’s water supply sources, saw its level rise, following the recent storms. While recent precipitation statewide is a good sign, the state is not out of the drought and the District is looking for ways to ensure enough supplies to meet demand this year.

PALMDALE — While the recent storms have helped the state and local water supply outlook, Palmdale Water District officials cautioned that the historic drought is by no means over.

“That rain really did help, but we’re still in a drought,” PWD Resource and Analytics Director Peter Thompson II said in a presentation to the Palmdale Water District Board of Directors, on Monday.

Late December and early January rain and snow helped move much of the state from exceptional and extreme drought conditions to severe and moderate conditions, he said.

Given the precipitation and snowpack in the Northern Sierras, the predominant source for State Water Project water, “you almost couldn’t have asked for a better start to the water year,” Thompson said. 

The water year begins on Oct. 1.

The Northern Sierra snowpack precipitation stands at 31.5 inches, which is 150% of average and at the same point for two of the state’s wettest years.

However, that kind of precipitation needs to continue through the winter and early spring to truly have an impact.

With a dry forecast for the remainder of the month, it is expected that snowpack will stand at 130% of average at the end of January.

Should the remainder of the year have average precipitation, it won’t be enough to end the drought because supplies are already so depleted, it will take extraordinary amounts to make up the difference.

An average year of precipitation will only bring the allocation of State Water Project water — carried through the California Aqueduct to contractors such as PWD — to 20%, Thompson said. 

At this point, the Department of Water Resources has said the allocation for 2022 will be 0%, with only enough water released to ensure health and safety. The allocation should be further determined at the end of January.

Water levels in the Oroville and San Luis Reservoirs — which provide much of the water sent to Palmdale through the State Water Project — remain below average, at 78% and 52% of their historical averages, respectively.

“We have a lot of hole to fill with water at this point,” Thompson said.

With little water available through the State Water Project, Palmdale Water District turns to its groundwater rights for supplies.

The District has 17,000 acre-feet of groundwater rights available to it for 2022.

An acre-foot is 325,851 gal­lons, or approximately the amount of water a typical Antelope Valley house­hold used in one year be­fore recent droughts reduced usage.

However, due to limitations of its wells, the District can only access 8,000 to 11,000 acre-feet, depending on the well performance, Thompson said. He uses the lower estimate for conservative projections of water supply availability.

Littlerock Dam, another water supply source for the District, has about 1,500 acre-feet supply, of which about 1,200 acre-feet is usable, as water is lost during transfer through the Palmdale Ditch to Lake Palmdale for treatment, he said.

With a 0% allocation from the State Water Project, the District does have about 500 acre-feet of water it didn’t use in prior years held in San Luis Reservoir.

The District has used exchanges with other water agencies during wet years to bolster its supplies in dry times. This year, however, most of those exchanges also have no water available, with a 0% allocation. Some portion of the exchanges may be made with a higher allocation from the State Water Project.

An agreement with the Kern County Water Agency will allow the District to pull 1,800 acre-feet this year.

“We can count on that as a part of our supply,” Thompson said.

All together, the District is looking at 11,350 acre-feet of supply for 2022, at this point.

Customer demand, based on a 15% reduction from 2020 usage, is projected at 17,425 acre-feet, Thompson said, which leaves the District short 6,125 acre-feet.

Several variables could change this shortfall in the coming months.

For one, Littlerock Dam, which is fed by the surrounding San Gabriel Mountain watershed, is rising and is expected to continue to fill, at least somewhat.

The District may be able to access more groundwater with improved pumping at its wells and the State Water Project allocation could increase.

“Roughly at about 20% (allocation), we start looking good,” Thompson said.

This District is also investigating other potential transfers and exchanges with water agencies.

On the demand side, increased water conservation measured by customers could help close the gap, if it cannot be done on the supply side.

Voluntary conservation measures may be increased from 15% to 20% and they could be made mandatory, he said.

The District has until April to “really get a good feel” as to what the supplies and possible gap will be, he said.

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