Water & Drought

Crews begin work on drought fix at Folsom Lake

Workers inspect pipes along the top of Folsom Dam that will connect to a floating pumping barge.
Workers inspect pipes along the top of Folsom Dam that will connect to a floating pumping barge. U.S. Bureau of Reclamation

As water regulators continue to rapidly drain Folsom Lake to bolster supplies downstream, crews have begun construction of a floating barge that could keep water flowing to the city of Folsom this fall.

The U.S. Bureau of Reclamation, which operates the reservoir, has allowed roughly 42 billion gallons to flow from Folsom Lake in the last 30 days. The lake now stands at its third-lowest point for this time of year in at least 40 years. At current outflows, Folsom Lake would reach record-low depths within weeks.

Local water agencies take water from Folsom Lake through huge intake valves well below the surface. The fear is that the reservoir level would drop to the point where the intakes would not function properly.

Several Sacramento suburbs, including Folsom, rely primarily on Folsom Lake for their water supply. In recent months, the Bureau of Reclamation has sharply decreased flows out of Lake Shasta and increased flows out of Folsom Lake to protect fish and maintain the right amount of salinity in the Sacramento-San Joaquin Delta.

The $3.5 million barge under construction would pump drinking water to more than 60,000 people in the city of Folsom and the nearby state prison complex should the lake’s water line drop below 330 feet above sea level.

As of Thursday, the lake level was at 376 feet. In the last four weeks, the lake has lost about 3 feet of depth every four days.

“Our goal is to never have to need (the barge),” said Erin Curtis, a spokeswoman for the Bureau of Reclamation. “But we don’t have total control over that.”

Federal officials say they felt it necessary to start building the barge as a precaution, even though they don’t think the lake will drop to levels that would require its use.

When it’s finished, the barge will float on the city side of the reservoir near the dam. It will consist of five floating platforms, each the size of a car and housing two submersible pumps. The pumps would funnel water through massive pipes along the top of Folsom Dam that would feed directly into the city’s intake system. The hope is to have the setup ready by Oct 1.

“We don’t want that to be operational,” said Marcus Yasutake, the city’s environmental and water resources director. “But we understand that’s the planning that Reclamation needs to do.”

Three cities and water districts serving more than 200,000 people rely on Folsom Lake for drinking water. Along with Folsom, they include the city of Roseville and the San Juan Water District, which serves Granite Bay and sells water to Fair Oaks, Citrus Heights and Orangevale.

To lessen their dependence on the shrinking reservoir, the region’s utility managers have been aggressively entering into water-sharing agreements or have beefed up groundwater supplies. Curtis said existing infrastructure should be adequate to supply Roseville and the San Juan district this summer and fall.

Shane Hunt, a Bureau of Reclamation special projects manager, said the barge project is smaller than one discussed earlier this year that would have served a larger segment of the Sacramento region’s urban water users if lake levels plummeted as low as originally feared.

Hunt said a larger barge or some other mechanism would be needed next spring only in the event “it’s really, really, really dry, and Folsom levels don’t come back up this winter.”

As of Thursday, there were about 242,000 acre-feet of water in Folsom Lake. Officials hope to keep the reservoir from dropping below 120,000 acre-feet at its lowest later this year. The lake has never fallen below 140,000 acre-feet, according to state records starting in 1976.

Hunt said that, thanks to reduced agricultural demand, Folsom Dam managers are beginning to ease off releases. In mid-July, the lake was losing 5,000 to 6,000 acre-feet of water each day. This month, that was lowered to 3,000 to 4,000 acre-feet per day.

In the fourth straight year of drought, water managers have leaned heavily on Folsom as well as the state-operated Lake Oroville on the Feather River. More water has been kept in Lake Shasta, the state’s largest reservoir, to store more cold water for endangered salmon.

Ryan Sabalow: 916-321-1264, @ryansabalow