Drought socks hydroelectricity, putting California in a power pinch

Rob Nikolewski, The San Diego Union-Tribune on

Published in Weather News

The annual snapshot of California's electricity generation shows how much drought conditions can affect the state's power mix.

In-state hydroelectricity generation in 2020 dropped 44.3 percent from the year before, according to numbers recently released by the California Energy Commission. All told, 21,414 gigawatt-hours came from a combination of the state's large and small hydro power plants — significantly lower than the 38,494 gigawatt-hours hydro delivered in 2019.

The state's electricity from sources that do not emit carbon — renewables, nuclear power and large hydro projects of at 30 megawatts or more — accounted for 51 percent of generation within California last year, down 6 percent from 2019.

"The change is directly attributable to the significantly reduced hydroelectric generation ... as dry conditions returned to the state," the energy commission explained in its breakdown of the numbers.

Hot, dry weather sucks up water levels at hydro facilities and reduces their electricity output. Conversely, when there's plenty of rain and snow runoff, hydro generation swells.

For example, the winter of 2016-2017 saw some parts of California reporting snowpack levels of more than 180 percent of normal. Months later, the energy commission reported large hydro made up 17.89 percent of in-state generation for the 2017 calendar year. When combined with small hydro that year, hydroelectricity accounted for more than one-fifth of California's electric generation.


But the drought's continuation has made conditions worse in 2021, as reservoirs around the state see water levels drop.

The Edward Hyatt Power Plant at Lake Oroville in Northern California may be forced to close for the first time in its history. The Chico Enterprise-Record reported Tuesday that Lake Oroville reached its lowest level since September 1977, measuring 643.5 feet above sea level. When it's full, the lake's surface water level is 900 feet above sea level.

Lake Shasta, the largest reservoir in the state, was 31 percent full as of Monday, according to the U.S. Bureau of Reclamation.

As for 2020's numbers, the drop in hydro power was offset by a number of sources.


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