Folsom Lake water levels will likely drop to historic lows by summer’s end, possibly hovering just above the point where cities and water agencies can still draw water from the reservoir, according to interviews with federal and local officials.
The nation’s attention turned to Folsom Lake early last year as photos of a long-submerged mining town and miles of dry lakebed captured the severity of California’s drought. At its lowest point during that period, Folsom Lake contained about 150,000 acre-feet of water, or roughly 15 percent of capacity.
This year could be worse. The U.S. Bureau of Reclamation has sharply increased flows out of Folsom this month to protect fish and maintain the right amount of salinity in the Delta. The lake is at its lowest point for this time of year in decades. And hardly any snowmelt will flow to the rescue from the Sierra.
Federal officials have set a target of “120,000 acre-feet or higher at the lake” by the end of September, Bureau of Reclamation spokeswoman Erin Curtis said. Folsom Lake levels have never been that low. Intake valves that draw water from the lake may not work if levels fall to 80,000 or 90,000 acre-feet, local water officials said.
Folsom Lake is the primary source of urban water for several Sacramento suburbs, including Folsom, Roseville and Granite Bay. It is part of a much larger system of dams and reservoirs that make up the state and federal water projects that pipe freshwater to cities and farms statewide.
Sacramento-area water agencies are “gravely concerned, just gravely concerned,” said Tom Gray, general manager for the Fair Oaks Water District. “The fact that they have a plan to operate down that low – it’s saddening. It gives absolutely no wiggle room.”
Tom Gohring, executive director of the Sacramento Water Forum, said the region will, in theory, be able to draw needed water from Folsom Lake if levels fall to 120,000 acre-feet. But that theory has never been tested.
“We’ve never been that low, not since they’ve built the dam,” Gohring said. “Even though the engineers say it will work, we don’t know.”
The Bureau of Reclamation “is in the process of building an emergency pumping plant that they will put in the reservoir so that they can still access water” if water levels fall too low for intake valves to work, Gohring said. “We have an insurance policy.” But, he added, “the bureau has never built one of these before.”
Folsom Lake is caught in a cascade of decisions that attempt to balance environmental concerns about fish, the drinking water needs of California and the demands of hundreds of thousands of residents in the Sacramento region.
The drought reduced water in the state’s reservoirs. Cold-water flows from Shasta Lake, one of the largest of those reservoirs, support winter-run Chinook salmon. But Lake Shasta is running warm this year, and officials and environmentalists fear a massive die-off of Chinook salmon. To avoid that possibility, they have curtailed water releases from Lake Shasta.
But water that normally would come from Shasta still must still flow into the Sacramento-San Joaquin Delta, or else the Delta will become too salty, threatening the drinking water for millions of Southern California residents.
In response, officials have increased flows out of Folsom Lake and other reservoirs. Water is flowing out of Folsom at roughly 3,000 cubic feet per second, Curtis said. That’s double the outflow from late May, federal data show.
Reclamation needs to increase flows from Folsom Lake “to manage the salinity in the Delta,” Curtis said. “It’s a linchpin in the system. If it gets too much saline ... it would be very, very bad.”
Curtis said Reclamation officials still aren’t sure exactly how low Folsom Lake will drop this year. “We are basically operating the system in real time,” she said. “We are looking at forecasts, but we are having to make decisions based on, ‘What is the highest priority and where is the water right now?’” The plan to manage temperatures at Lake Shasta sets a minimum of 120,000 acre-feet in the lake by October but, Curtis said, officials do not yet have “as high a degree of certainty in the plan.”
John Woodling, executive director of the Regional Water Authority, said “I don’t think we would expect that projection to end up a whole lot better” because of the lack of snowmelt and the upcoming dry summer. Local water districts instead hope for early season precipitation so “it doesn’t get much lower than that in the fall and winter.”
The State Water Resources Control Board will hold a workshop Wednesday to discuss efforts to control temperatures at Lake Shasta – and the resulting problems. Several local officials said they would attend that meeting to argue for protections on Folsom Lake.
“Where are the assurances, the safety net for the Sacramento region’s water supply?” Gray asked.