Shasta Lake, the largest reservoir in California, rose more than 30 feet over the past two weeks as a series of winter storms battered the state, according to state data.
The heavy inflow over the holidays, with Shasta Lake rising 10 feet alone between Friday and Monday, pushed water levels in the sprawling Northern California reservoir to nearly 80% of capacity, which is well above what it typically holds this early in the rainy season. And the leakage is still coming in, albeit at a slower rate.
While winter is still young and California’s water picture won’t be clear for months, the recent replenishment of Lake Shasta, as well as other major reservoirs, is welcome news for cities and farms across the state, which rely on the water that fills these giant storage facilities between fall and spring.
“Reservoirs in general are running ahead of average, which is good,” said Michael Anderson, state climatologist at the California Department of Water Resources, in a report Tuesday to the State Water Resources Control Board.
Before the holidays, water managers were getting nervous after a largely dry start to the state’s best wet season, which runs from December to March. But starting just before Christmas, an extremely wet pattern locked in, bringing more than a foot of rain and several feet of snow to parts of California over a two-week period.
“Over the Christmas holidays, we had over 100 hours of river weather conditions in the state,” Anderson said.
Shasta Marina at Packs Bay on Shasta Lake is seen in January 2023 after several major storms. (Carlos Avila Gonzalez/The Chronicle)
As a result, water storage in Shasta Lake has risen to 132% of average for the date, as of Monday. Storage in Lake Oroville, the state’s second largest reservoir, rose to 135% of average. Storage in Trinity Lake, the state’s third-largest reservoir, hit 137% of average.
Meanwhile, Hetch Hetchy Reservoir in Yosemite, which is San Francisco’s primary storage facility, had 130% of the water it typically holds on this date.
Many reservoirs have been making releases to ensure adequate space for continued precipitation and continued runoff. The waters of Shasta Lake were about 35 feet below the rim of the reservoir.
“We are on the declining side of inflows with these last systems,” said Levi Johnson, operations manager at the federal Bureau of Reclamation, which manages Shasta Lake. “This is going to be a dynamic operation in terms of what kind of releases we have.”
Storms seem to be mostly on their way. The National Weather Service is forecasting dry conditions for at least the next two weeks.
While California’s water picture remains strong, water managers will be watching to see how long it will be before the next rain and snow arrives and whether it will be enough to maintain robust reservoir storage.
Another factor that water managers are monitoring is snow in the far north of the state. While California’s total snowpack is 90% of average for the date, the Northern Sierra and Southern Cascades are only 67%.
Snow is important, particularly in Northern California where the state’s largest reservoirs are located, because it melts and provides a source of water for the reservoirs after the rainy season ends.
“We’ve had a lot more rain than snow,” Anderson said.
This article originally published in California’s largest reservoir rises 30 feet after recent storms.