California reduces Delta pumping amid ample reservoirs and snowpack. Here’s why
California water managers this week cut in half the amount of water being pumped from the Sacramento-San Joaquin Delta at the state’s plant near Tracy, saying the main reservoir it serves is nearly full and the water is needed for fish.
The reduction is required under the state’s environmental permits for pumping from the fragile Delta, because despite nearly full reservoirs and a robust snowpack, the San Joaquin River watershed had less-than-normal precipitation during the water year which began Oct. 1, said Ryan Endean, a spokesperson for the California Department of Water Resources.
The state’s Banks Pumping Plant lifts water from the Delta to canals and reservoirs that serve San Joaquin Valley farms and Southern California cities. But environmental regulations require pumping to be reduced in the spring months of March, April and May to protect fish, including spring-run Chinook salmon, Delta smelt and longfin smelt, DWR officials said in a news release.
The reduction in pumping comes at a time when reservoirs in Northern California are mostly full, and the spring snowpack, which melts during the summer months and serves as a vital source of water during the dry season, is strong for the third year in a row.
Lake Oroville, the capstone of the state reservoir system, was at 120% of its historical average on Friday, state data shows.
And San Luis Reservoir, the one fed by the Banks pumping plant, was at 105% of its usual average and 90% of capacity. Snowpack measurements across the Sierra at the end of March showed snow-water levels at 90% of average statewide, buoyed by a stronger snowpack in the Feather River watershed in the north.
Parts of Southern California, however, remain in a persistent drought, data released Thursday by the U.S. Drought Monitor shows.
The reduction also comes several weeks after an executive order by President Donald Trump to increase flows of water through the systems that the federal government operates in California, including a pumping plant at the Delta.
On Thursday, pumping at the State Water Project facility was cut to 600 cubic feet per second from 1,200 cfs, the state agency said. By comparison, last year pumping was cut by about 30%, also on April 9, Endean said.
The drop was anticipated by the agencies that provide water to California farms and communities, said Jennifer Pierre, general manager of State Water Contractors, an organization that represents public water agencies.
Because of the state’s strong water position and late winter rains, the anticipated reduction in pumping levels was actually delayed nine days from the start of April when it would typically kick in, allowing contractors to bolster their supplies, she said.
“We were grateful for the nine days,” she said. “There was significant flow.”
But she questioned whether the drop in flow in recent days was really significant enough to warrant cutting pumping by half, and urged regulators to consider adopting a more flexible program, under which pumping might increase more nimbly in the wettest months and decrease during drier periods.
Barbara Barrigan-Parilla, executive director of the environmental organization Restore the Delta, welcomed a reduction in pumping. But she questioned the state’s explanation, arguing that if the federal government had not increased its pumping, the state — which serves different communities — might not have needed to scale back.
She urged Gov. Gavin Newsom to push back on the federal policy.
“If they don’t hold the federal operators accountable, there is going to be an imbalance between meeting the water needs of the Central Valley water systems and the farmers, and we’re never going to get in balance to save the estuary,” she said.
Endean, the state spokesperson, said the reduction was unrelated to any federal action.
“The actions are required as part of our operating permit to protect endangered fish species,” he said.
A new plan for increasing the flow of water for fish that would not rely solely on pumping from the Delta is under consideration by the State Water Resources Control Board, the agency said on its website. That program, if adopted, would lead to more water in the rivers before they reach the Delta, expanding the habitat for fish, the agency said.
Shasta Lake, the state’s largest reservoir and the keystone of the federal Central Valley Project, stood at 94% of capacity on Friday, holding 116% of its historical average. Nearby, Trinity Lake reached 88% of capacity, or 118% of average for this time of year, according to DWR measurements.
Folsom Lake, which provides crucial flood protection for the Sacramento region, measured at 92% of capacity, a significant 138% of its historical average.
In the Sierra foothills, New Bullards Bar Reservoir reported storage at 90% of capacity, tracking at 114% of historical average. New Melones Lake, another key source for the San Joaquin Valley, registered 83% of capacity, or 134% of its typical level for early April.
This story was originally published April 11, 2025 at 3:11 PM.
