State water officials have begun releasing water from some of California’s most important reservoirs as the latest series of atmospheric river storms is expected to pile more snow on top of an already impressive Sierra Nevada snowpack.
With as many as four atmospheric rivers making landfall in Northern and Central California during the current wave, state and federal water managers recently announced plans to increase releases from reservoirs up and down the state.
The releases are intended to preserve reservoir capacity for later in the year when the state’s near-record snowpack begins to melt, sending additional water into its two massive water storage and delivery systems, the State Water Project and the federally run Central Valley Project.
“All efforts are being made to manage water supply and flood control during these storms,” said California Department of Water Resources (DWR) director Karla Nemeth.
During a media briefing on March 9, Nemeth said last weekend’s storm that resulted in flooding on the Pajaro River and other parts of the region was also likely to result in rainfall at higher elevations leading to “increased direct runoff from the rain and accumulated snow at lower elevations and all of this could contribute to significant runoff.”
Things are different now
In January, when a similar series of large storms lashed the state for many days, the state’s reservoirs were collectively at near-record lows and had the capacity to safely handle large inflows of water.
This time around, however, many of those same reservoir levels are at or near their historical averages for this time of year and have reached the point at which federal regulations require them to release water, partly so they will have the ability to take in more when the Sierra snowmelt happens later in the spring and early summer.
For example, the water level at Folsom Lake on the American River is at about 113 percent of its historical average and managers with the U.S. Bureau of Reclamation began increasing the amount released from its dam from 5,000 cubic feet per second (CFS) to 30,000 CFS as of March 10, said Levi Johnson, deputy operations manager for the Central Valley Project. The release rate as of March 15 had been reduced to 20,000 CFS.
“These releases are in anticipation of the inflows due to these storms. We will be prepared to increase (releases) further if needed and as we see how the inflows from these storms shape up.”Levi Johnson, Central Valley Project
“These releases are in anticipation of the inflows due to these storms,” Johnson said. “We will be prepared to increase (releases) further if needed and as we see how the inflows from these storms shape up.”
Also, the Friant Dam at Millerton Lake, which is at about 70 percent of its historical average, as of March 15 was releasing about 6,500 CFS into the San Joaquin River, but that could change depending on how this series of storms shapes up, Johnson said.
At Lake Oroville, which is operated by DWR and is at 116 percent of average, managers are currently releasing 25,000 CFS into the Feather River, said Ted Craddock, deputy director of the State Water Project.
Lake Shasta in Shasta County is currently at about 83 percent of its historical average and managers increased releases to as high as 4,750 CFS from the dam into the Sacramento River this past Tuesday.
Great for groundwater
In addition to their flood control function, the releases have the benefit of helping recharge groundwater tables in some areas that were hardest hit by the last three years of punishing drought.
Groundwater recharge is seen as vital for the health of the more than 100,000 domestic wells considered to be in areas at risk of running out of water.
“California is taking advantage of all these winter storms to increase groundwater recharge efforts,” Nemeth said. “That means taking excess stormwater and storing it underground to rebuild groundwater supplies.”
Nemeth said the state is trying to significantly expand its ability to recharge groundwater basins, in part by working to clarify the permitting process with local agencies that are running recharge projects.
Also, the State Water Resources Control Board recently approved a request from the Bureau of Reclamation to divert more than 600,000 acre feet of San Joaquin River water for wildlife refuges and groundwater recharge projects from March 15 through July 30.
“It’s an opportunity to pick up some of the extra flows and divert it off the river system and store it underground,” said Erik Ekdahl, the Water Board’s deputy director of water rights.