Folsom Lake’s water level sank to its lowest level in history Saturday, a vivid reminder of California’s epic drought even as a new winter storm moved into the region.
The 60-year-old reservoir held 140,501 acre-feet of water at midafternoon, or roughly 14 percent of capacity, according to California Department of Water Resources data. The lake fell below the old record of 140,600 acre-feet, a mark seen during the 1977 drought, around midnight Friday and continued falling through the day.
“Certainly a milestone we didn’t want to see happen,” said Eric Kurth, a forecaster with the National Weather Service in Sacramento. An acre-foot is 326,000 gallons.
Kurth said the latest storm was expected to bring rain to the Sacramento region and snow to the Sierra throughout Sunday, for the third weekend in a row. A winter weather advisory was issued for travelers in the Sierra, which has already seen several ski resorts open early for the season.
“We are building up a snowpack with all these (weather) systems, which is encouraging,” he said.
Despite the recent series of storms, and predictions of one of the largest El Niño systems on record, most experts say California is unlikely to get enough precipitation this winter to make up for four years of drought. Gov. Jerry Brown on Friday issued an executive order that makes it all but certain that urban conservation mandates will remain in effect through next October.
Folsom Lake’s dubious record was hardly a surprise. State and federal officials have warned for months that Folsom was going to be drained to record-low levels this fall as part of a complicated but likely unsuccessful effort to keep alive as many winter-run Chinook salmon as possible. That sparked concern among the suburban water agencies that rely on Folsom to deliver drinking water to approximately 200,000 residents.
As a precaution, the U.S. Bureau of Reclamation built a series of temporary pumps that could draw water out of Folsom even if lake levels fall well below the permanent intake valves. However, bureau officials said recently they don’t think the temporary measures will be needed and the suburban water supplies will remain intact.
Still, it’s expected that lake levels could drop even further.
The draining of Folsom Lake began when officials realized the water on the Sacramento River was running hotter than expected. They throttled back the releases from Shasta Lake in order to keep cold water in the system and hopefully preserve the juvenile winter-run salmon, which need water temperatures of 56 degrees or less to survive. With reduced flows out of Shasta, officials ramped up the releases from Folsom to keep the Sacramento-San Joaquin Delta from being inundated with salt water from the ocean. The Delta is the hub of California’s man-made water delivery system.
In spite of the temperature-control plan, officials fear that most of the juvenile salmon died this year anyway. More definitive results are expected to be released soon. The salmon are an endangered species.
Kurth said the latest storm was likely to hit the Sacramento region around dawn Sunday and reach the Sierra soon after. Snow was expected at altitudes as low as 4,500 feet by afternoon, he said.
“We have a pretty good supply of cold air,” the forecaster said.
Kurth said temperatures in Sacramento aren’t expected to climb above 57 degrees Sunday. The weather was expected to dry up the next few days, and temperatures would climb back into the 60s by Tuesday.