Lake Sonoma, nearly full, reflects ample local water supply for summer

With more than half of California still in a severe drought, Sonoma County’s water supply remained secure Friday, with Lake Sonoma, the region’s largest reservoir, at 96 percent of its supply capacity, 16 percent higher than it was this time last year.

That plentiful pool and runoff throughout the watershed has boosted flow down the Russian River. At Hacienda Bridge near Guerneville the river ran at 164 cubic feet per second this week, more than 50 percent above the river volume last year.

After several drought-diminished summers, the numbers add up to something that boaters and sunbathers already know.

“It’s beautiful out there,” said Ann DuBay of the Sonoma County Water Agency. “Thanks to the steady, later rains, we have more water in the river than we have had for several years.”

And the near future looks promising, as the Water Agency reported last week that Lake Sonoma by summer’s end would still hold two to three years of water for North Bay customers, enough to withstand a drought comparable to the stretch from 2013 to 2015.

Based on that forecast, Santa Rosa this month rescinded mandatory curbs on outdoor water use adopted two years ago.

Lake Mendocino, the smaller of the two reservoirs in the Russian River watershed, was at 77 percent of capacity, up a whopping 57 percent over last year at this time.

Together, the two reservoirs help supply water to more than 600,000 North Bay residents.

Lake Mendocino serves people and ranches from Ukiah to Healdsburg and helps maintain summertime flows along the upper Russian River.

Farther north, Lake Shasta and Lake Oroville, the state’s two largest reservoirs, were also in good shape Friday, both above average for this time of year. Shasta was at 88 percent of capacity and Oroville was at 87 percent.

Six of the state’s 12 largest reservoirs were over 70 percent of capacity, according to the state Department of Water Resources.

But as federal officials agreed to increase the release of water from Shasta Dam down the Sacramento River, boosting prospects for Sacramento Valley rice farmers, concerns emerged that the state might run short of water for both farmers and endangered fish during the hot summer months ahead.

The Sierra Nevada snowpack, which typically refreshes Shasta and the other major reservoirs during the summer, is virtually gone.

On Friday, just 0.5 percent of the Sierra was covered with snow at an average depth of 0.1 inches, the National Weather Service reported. A month ago, 18.7 percent of the mountains were coated white, with an average snow depth of 5.6 inches.

May and June temperatures were about average, but the Sierra received below normal precipitation.

Fifty-nine percent of California is in severe, extreme or exceptional drought, the U.S. Drought Monitor reported Thursday.

A year ago, nearly 95 percent of the state was in the same situation.

Sonoma County and the western half of Mendocino County were rated Thursday as abnormally dry, the lowest of five drought categories.

The Russian River watershed, which supplies much of the region with its drinking water, is not part of California’s massive network of reservoirs and aqueducts that depends heavily on the Sierra snowpack.