LOS ANGELES — A week of powerful storms in Northern California has significantly eased the state’s water shortage, with a large swath of the state emerging from drought conditions, officials said Thursday.
The numbers underscore what officials have been saying for several months about the drought. As a series of storms have hit Northern California this winter, the drought picture there is easing, but is still more of a factor in Southern California and the Central Valley.
According to the U.S. Drought Monitor, well over 30 percent of the state is no longer in a drought. Last week, that number was 18 percent.
This week’s drought monitor map shows no drought conditions through a huge swath of Northern California, but serious water woes to the south. The most severe drought remains in parts of Los Angeles, Ventura and Santa Barbara counties.
The storms drenched the Bay Area and created blizzard conditions in parts of the Sierra Nevada over the last week. The storms dramatically boosted the Sierra snowpack — a key source of water for California — to 158 percent of normal and made a significant dent in the state’s six-year drought.
But the weather systems also left a path of destruction. The storms likely caused at least four deaths.
Since Oct. 1, total precipitation in the Sierra Nevada has been soaring at rates similar to the wettest winters in the modern record: 1982-83 in the northern and central Sierra and 1968-69 in the southern Sierra.
Lake Shasta, the state’s largest reservoir and a major source of water for San Joaquin Valley agriculture, is 81 percent full and releasing water to create more storage room. Oroville, which supplies the State Water Project, is nearly three-quarters full.
In much of Southern California, the dry autumn has given way to above-average rainfall that is helping replenish local groundwater basins that typically provide roughly a third of the region’s water supply.
Numerous Northern California and Nevada rivers flooded, forcing thousands to flee their homes. While the storms were beginning to taper off Wednesday, officials said they are still on high alert.
“The ground is saturated,” said Edan Weishahn, a meteorologist in the National Weather Service’s Reno office. “They can’t handle any more water, so any more we get, it’s all runoff into the streets.”
In Guerneville in Sonoma County, the Russian River flooded from the combination of melting snow and more than 12 inches of rain that have fallen since early last week across the region. Hundreds of Sonoma County residents were displaced as the waters peaked at 37.7 feet, said Jennifer Larocque, a spokeswoman for Sonoma County’s Transportation and Public Works department.
The last time the Russian River eclipsed that level was during a major storm that began on New Year’s Eve 2005 and sent rain onto the Rose Parade in Southern California days later.
In Sacramento, a tornado ripped across a suburb for about half a mile early Wednesday morning, damaging trees and homes but not injuring anyone.
In the northern Sierra Nevada, where some peaks have received 12 feet of snow in a week, residents were told to stay indoors Wednesday as heavy snowfall was again expected overnight. In Washoe County on the Nevada side of Lake Tahoe, a “snow emergency” was declared for the first time in a decade, and residents were told to stay inside, the National Weather Service said.
“We haven’t had a break between our very wet weather that we got early this week and another round of precipitation we had last night. At this point, it just seems like they’re all running together,” Weishahn said.