Even as Sacramento waits for the soaking El Niño forecast to hit this fall, Folsom Lake continues to lose water and will almost certainly fall Thursday to its lowest level in more than 20 years, government data show.
Folsom Lake provides drinking water to hundreds of thousands of residents in the Sacramento region. Releases from the federal reservoir also serve as a bulwark against Sacramento-San Joaquin Delta saltwater intrusion, and are critical to maintaining the delicate ecosystem of the lower American River.
On Wednesday afternoon, Folsom Lake had about 162,000 acre-feet of water – just 17 percent of its capacity – and operators were still releasing about 800 acre-feet a day, according to the California Department of Water Resources. The lake typically has about 530,000 acre-feet this time of year. An acre-foot is about 326,000 gallons of water.
Folsom Lake became the face of California’s drought early last year when aerial photos of its moonscape lake bed were broadcast nationwide. At its lowest point last year, the lake level was the same as what the reservoir contained Wednesday. By Thursday, the reservoir is expected to fall to levels last seen in 1992, at the tail end of a five-year drought. And by month’s end, the depth likely will approach levels not seen since the great drought of 1977.
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Area water officials said they are concerned about the dwindling supply but expressed relief that lake depths are not even lower. The U.S. Bureau of Reclamation, which operates the reservoir, initially warned that the lake could fall to 120,000 acre-feet by the end of September.
“The situation has been so rough,” said bureau spokesman Shane Hunt. “We are doing everything we can to make sure we maintain water supplies to homes.”
Still, he added, “We are better than a worst-case scenario.”
The Bureau of Reclamation began draining Folsom at a rapid pace in the early summer to protect an endangered species of salmon. By sending more water downstream from Folsom Lake, officials were able to reserve more cold water in Lake Shasta. Winter-run Chinook salmon rely on cold flows from Shasta Dam to survive as they hatch in the Sacramento River.
As a precaution, bureau officials simultaneously built a series of platforms and pumps that can draw water out of Folsom Lake should levels fall below the intake valves used by Sacramento-area communities for residential water supplies. Those intake valves can, in theory, work until lake storage hits about 85,000 acre-feet.
“Everything has been installed, tested and is ready to go,” Hunt said.
But, at this point, he said, “we still don’t think we will need” the platforms and pumps. Operators were able to keep more water behind Folsom Dam than once feared because of better than expected “inflows ... and our ability to manage demand,” Hunt said.
The bureau plans to reduce flows out of Folsom starting Thursday, and will try to keep releases relatively low until it rains, Hunt said.
Marcus Yasutake is the environmental and water resources director for the city of Folsom, which relies on the reservoir for much of its water supply. Despite the bureau’s assurances, Yasutake said he is concerned. “I will remain concerned until we have a nice snowpack and a good amount of rainfall coming in,” he said.
Tom Gray, general manager for the water district that serves the community of Fair Oaks a few miles from the lake, said predicting how low the reservoir will fall this winter is difficult – and worrisome. He noted that October has been unusually warm so far, meaning residents are continuing to run their sprinklers when they typically would be easing off. That’s made for higher demand.
“There is a perception that we are going to squeak through,” he said. But, “the lake is 17 percent right now, and it is 90 degrees outside. If we don’t see rain soon, it’s going to be down to that critical level.”
The last time Folsom Lake fell below 162,000 acre-feet was during the winter of 1992, when it bottomed out around 156,000 acre-feet. The lake’s lowest point on record of 140,600 acre-feet was reached in November 1977, just before the break in that decade’s two-year drought.
Visits to the lake have fallen along with water levels, in large part because the launch ramps for boats are no longer accessible, leaving boaters to launch from the muddy lake bed. During July and August, the park took in $50,000 less in revenue than the prior year, said Folsom Lake State Recreation Area Superintendent Richard Preston. The park is still open, but Preston said visitors should be aware that the actual water “is such a distance from the shore.”