Lake Shasta, California’s largest reservoir, has risen more than 30 feet in the past two weeks as a series of winter storms hit the state, according to state data.
Lake Shasta rose 10 feet between Friday and Monday due to heavy inflows during the holidays, causing the water level in Northern California’s massive reservoir to reach nearly 80% of capacity, well above typical levels early in the rainy season. Runoff is still pouring in, albeit at a slower pace.
While winter is still early enough and California’s water conditions won’t be clear for months, the recent replenishment of Lake Shasta and other major reservoirs is good news for cities and farms across the state that rely on water filling these vast storage facilities between fall and spring.
“Reservoirs overall are operating at an above-average rate, which is good,” California Department of Water Resources climatologist Michael Anderson said in a report to the state Water Resources Control Board on Tuesday.
Ahead of the holidays, water managers are nervous at the start of the state’s largely dry rainy season, which runs from December to March. But starting on Christmas Eve, an extremely wet pattern locked in, bringing more than a foot of rain and several feet of snow to parts of California in two weeks.
“Right around the Christmas holidays, atmospheric river conditions persisted over the state for over 100 hours,” Anderson said.
In January 2023, after several major storms, the Shasta Marina at Parks Bay on Lake Shasta emerged. (Carlos Avila Gonzalez/The Chronicle)
As a result, as of Monday, Lake Shasta’s water storage capacity climbed to 132% of the day’s average. Storage capacity in Lake Oroville, the state’s second-largest reservoir, rose to 135% of average. Trinity Lake, the state’s third-largest reservoir, is at 137% of average.
Meanwhile, Hetch Hetchy Reservoir in Yosemite National Park, San Francisco’s main water storage facility, held 130% of its usual water capacity that day.
Many reservoirs have been releasing water to ensure there is enough room to accommodate continued precipitation and continued runoff. The water level in Shasta Lake is about 35 feet below the edge of the reservoir.
“The inflows from these newest systems are tapering off,” said Levi Johnson, operations manager for the federal Bureau of Reclamation, which manages Lake Shasta. “It’s going to be a dynamic operation in terms of the releases we have.”
The storm appears to be abating. The National Weather Service is predicting drought conditions for at least the next two weeks.
While California’s water situation remains strong, water managers will be closely watching the time until the next wave of rain or snow arrives and whether it will be enough to maintain strong reservoir storage.
Another factor water managers are monitoring is snowfall in the far north of the state. While California’s total snowpack was 90% of the day’s average snowpack, only 67% of the snowpack was in the northern Sierra Nevada and southern Cascade Mountains.
Snow is important, especially in Northern California, home to the state’s largest reservoir, because it melts after the rainy season ends and feeds the reservoirs.
“We’re getting a lot more rain than snow,” Anderson said.
This article was originally published on Water levels in California’s largest reservoir rose 30 feet after recent storms.
