Chart Shows How California Reservoirs Changed After Atmospheric River

Water levels improved at several of California's major reservoirs after two atmospheric rivers brought torrential rain to the Golden State.

The first of two atmospheric rivers arrived last Thursday. Meteorologists were more concerned about the second atmospheric river, which arrived on Sunday and wreaked havoc with severe rain, snow and high winds.

The first system brought a deluge of rain that saturated the ground, making it prone to flooding with the second system. Catastrophic flooding did occur, particularly in Los Angeles County after more than 7 inches of rain fell. However, a chart by the California Department of Water Resources (DWR) showed that the rain also proved beneficial for many of the state's biggest reservoirs.

Water levels at Lake Shasta, Lake Oroville, New Bullards Bar Reservoir, Folsom Lake, Lake Camanche, Trinity Lake, Sonoma Lake, San Luis Reservoir, New Melones Lake, Don Pedro Lake, Lake Casitas, Castaic Lake, Millerton Lake, Pine Flat Lake and Lake McClure all improved from the rainfall with both atmospheric rivers, according to the chart.

Diamond Valley Lake water levels remained the same, at 93 percent of capacity and 127 percent of historical average.

Newsweek has reached out to the DWR by email for comment.

The improvement to the water levels comes after a years-long drought plagued California and depleted many of the state's lakes. Above average precipitation during the early months of 2023 alleviated much of the state's drought, and California was deemed free from drought for the first time in three years last fall.

After the rain, nearly all of the state's reservoirs' water levels are above their historical average. Only a few lakes remain below their historical average, including San Luis Reservoir at 81 percent of its historical average; Lake Casitas at 97 percent and Millerton Lake at 95 percent. The lakes are at 62 percent capacity, 77 percent capacity and 58 percent capacity, respectively.

Water levels at other reservoirs have improved so much that the DWR opted for a planned release through dam spillways to provide flood protection ahead of the moisture-laden storms.

Billions of gallons of water were released from Lake Oroville to mitigate flood risk, and the lake's capacity still rose by 1 percent. The main spillway has since been closed, but a DWR spokesperson previously told Newsweek that more releases could occur later in the year, dependent on the weather.

"DWR continues to monitor lake levels, weather forecasts and mountain snow levels to optimize water storage at Lake Oroville and meet environmental requirements while allowing for carryover storage into next year," the spokesperson said.

An estimated 62,122 acre-feet of water were released through the spillway while it was open.