When it comes to California’s water supply, 2018 will end with a whimper.
California’s two largest reservoirs are not even half full. The Sierra Nevada snowpack, which functions as an additional set of reservoirs, is below normal for this time of year.
And there’s not a major storm in sight.
“We’ll ring in the new year with mild, quiet weather,” Cory Mueller, a meteorologist with the National Weather Service in Sacramento, said Thursday.
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That doesn’t necessarily mean the state is heading into another drought. While December has been relatively dry in much of California, private weather forecaster Jan Null said January and February can easily make up for the slow start to the rainy season.
“I never panic; it’s way too early,” said Null, who runs a Bay Area consulting firm called Golden Gate Weather Services. “I’ve seen too many miracle Marches. But I’ve also seen it where it goes flat.”
Although Gov. Jerry Brown declared the state’s historic drought officially over in April 2017, dry conditions persist in much of the state. The weekly U.S. Drought Monitor, which is assembled by various federal agencies, says 75 percent of California is in moderate to extreme drought.
Although Christmas brought nearly a half-inch of rain to Sacramento, the city has only received 2.65 inches of rain this month — almost an inch below normal — according to National Weather Service records.
Perhaps more ominously is the condition of California’s two most important reservoirs, where much of the water for California’s two big federal and state water projects is stored. Shasta Lake, the linchpin of the federal Central Valley Project, is just half full, and at 80 percent of historical average for late December. Lake Oroville, which serves the State Water Project, is 29 percent full, and at 47 percent of historical average.
Complicating matters is that the Department of Water Resources plans to run Oroville emptier than usual this winter so it can complete the last of the repairs to Oroville Dam’s flood control spillways. DWR announced in October it plans to keep water levels 13 feet lower than normal to finish the work that’s been under way since 2017, when the two spillways suffered near-disastrous failures.
That 13 feet difference could translate into at least 100,000 acre-feet of water that can’t be stored this winter, possibly reducing supplies available to the State Water Project during the summer and fall. An acre-foot is 326,000 gallons, enough to supply an average California household for one to two years. The city of Sacramento’s water utility provided its customers around 86,000 acre-feet in 2015.
Meanwhile, the Sierra snowpack — often called the state’s largest natural reservoir — is lagging. The snowpack’s water content is at 78 percent of normal for late December, according to DWR data.
The snowpack, which will be surveyed on Jan. 3, plays a crucial role in California’s water health. As it melts during the hot, dry months, water flows into the massive network of reservoirs that ring California’s Central Valley.
They store the water and release it to cities and farms throughout the year. While currently below average, the Sierra snow is better than where it was at the start of this year, when it stood at just 53 percent of average. California’s snow season ended in April at 52 percent of average.
What happens the rest of this season remains unclear.
“Right now, I would say the season is in the low normal stage,” Null said.