California Reservoir Water Levels After Historic Rainfall

A historic amount of rain fell on California between December 26 and January 19 and as a result many of the state's reservoirs have seen rising water levels.

Most of California is still in the grips of a drought that has lasted for two decades and water levels in its reservoirs remain well below their historical average. However, the recent rain was so heavy that parts of the state changed their drought status— 97.93 percent of California is still experiencing drought, but the remaining 2.07 percent is classified as "abnormally dry."

California's reservoirs provide storage for water supply, and reduce flooding as a result. The water comes from winter and spring rainfall and snowpack running down through the mountains. That water is then used for irrigation and in municipalities.

Shasta Lake
A stock photo shows Shasta Lake in California. Since the heavy rainfall that began in late December, the lake's water levels have risen significantly. Strekoza2/Getty

There is ongoing concern about these reservoirs as weather patterns are unpredictable and many are drying up faster than they can be replenished.

So what do California's reservoirs look like now?

The state's largest reservoir, Shasta Lake in Shasta County, has seen a huge increase in water levels as a result of the recent heavy rains. On December 26, when the rains began, the lake was at 921.08 feet. Levels rose throughout January and as of February 2 the lake is at 987.93 feet.

In February 2022, the lake's elevation was at 934.14 feet, marking a 53-foot difference between now and the same period last year.

The lake is still well below its average elevation—when it is full, its water levels reach 1067 feet—but the rising water level is good news for the state.

California's second-largest reservoir by volume, Lake Oroville, north of Sacramento, saw water levels rise from 673 feet on December 26 to 810.38 feet on February 2—another dramatic increase.

The table below shows how much the state's 15 largest lakes have risen since the recent heavy rainfall began.

LakeWater Level (ft MSL) 12/26/22Water Level (ft MSL) 01/09/23Water level (ft MSL) 02/02/23
Shasta Lake921942987.92
Lake Oroville673735810.38
Trinity Lake2,1892,2042,226.36
New Melones Lake883908941.19
San Luis Reservoir412430479.39
Don Pedro Reservoir737765784.15
Lake Berryessa*394401412.1
Lake AlmanorNANANA
Folsom Lake386406416.52
Lake McClure676735800.47
Pine Flat Lake766801857.11
New Bullards Bar Reservoir1,8611,8901,915.53
Diamond Valley LakeNANANA
Lake Tahoe6,2236,2246,224.32
Lake Havasu447448447.64

Source: Lakes Online *Lake Berryessa data from Solano County Water Agency

Experts have warned that while the downpours had been welcome, it would take a lot more precipitation to address the ongoing water shortage.

"So far the rainfall in the northern Sierra Nevada, which our largest reservoirs depend on, is at about 40 percent of the annual average," Roger Bales, a water and climate engineer at the University of California, Merced, previously told Newsweek. "We need more precipitation, closer to the average, to refill the reservoirs. We need two to three more big storms in January-March."

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