The U.S Bureau of Reclamation will cut flows out of Folsom Lake in half by the end of the week as water levels at the reservoir near historic lows.
Folsom Lake is the primary water source for Sacramento suburbs serving hundreds of thousands of customers. At noon Monday, the lake held about 196,000 acre-feet of water, or about 20 percent of its capacity. The Bureau of Reclamation, which operates the reservoir, let out an average of 3,000 acre-feet of water, or roughly 1 billion gallons, each day during August. Early last year, at its driest, the lake never fell below 150,000 acre-feet.
Four years of drought have depleted the state’s major reservoirs, resulting in higher water temperatures. In response, officials earlier this summer cut flows from Lake Shasta to protect an endangered species of salmon dependent on cold water flows; in exchange, they raised flows from Folsom Lake to prevent saltwater from intruding into the Sacramento-San Joaquin Delta.
At the start of August, Reclamation officials released about 2,500 cubic feet per second from Nimbus Dam, which sits just below Folsom Lake. By Friday morning, flows out of Nimbus will be 800 cubic feet per second. During the last decade, median daily outflows at Folsom Lake in September were about 1,400 cubic feet per second, according to a Bee review of Reclamation data.
The change is “to conserve water in storage,” Reclamation spokesman Shane Hunt said.
Reclamation officials have pledged not to let Folsom Lake drop below 120,000 acre-feet. The concern is that water levels could drop below the point at which the pumping infrastructure that funnels water to suburban Sacramento might not work. As a contingency, Reclamation is building a specially outfitted barge that would pump water to the city of Folsom if the lake fell below the city’s intake valves.