Does Drought-Prone California Need Another Reservoir?

The Antelope Valley’s sweeping northern California pastures, dotted with cows and encircled by the gentle hills of the Coast Range, spread out about 50 miles north of Lake Berryessa, in Napa County. In five years’ time, if current plans become reality, the cows and grass would be replaced by a reservoir holding up to 1.5 million acre-feet of Sacramento River water. Antelope Valley’s new lake would look much like Lake Berryessa.

The construction of this new reservoir, named for the tiny town of Sites in Colusa County, came closer to reality last month. Combined with the expansion plans for two additional northern and central California reservoirs, this new storage could mean additional water to soften the sharp edges of megadroughts like the one now threatening farms, cities and the environment.

Financial support is crucial to all three projects. The financial picture of the $4.5 billion Sites project improved markedly in the last couple of months with announcements that it will receive a $2.2 billion federal loan and $875 million from a state bond. This news came as water year 2022 reached its halfway point with the dry months yet to come; it is following the flood-and-famine pattern of California’s weather.   

Atmospheric rivers are intensifying; two drifted across the state in October and December, leaving the Sierra snowpack 160 percent above average levels statewide in January. But that was almost the end of the rain and snow.  On May 11, the snowpack, a reservoir supplying about a third of the state’s water in average years, was 22 percent of average statewide. 

Despite some spring storms, a third year of wrenching drought seems inevitable. Already, two northern California reservoirs have declined to critical levels. At the same time, the prospects for the construction or expansion of three northern and central California reservoirs to store overflows from atmospheric rivers have brightened as the drought gets worse.