was 97% full.
Of particular note this year is the dramatic difference in precipitation between Northern California and Southern California.
The Northern Sierra snowpack on Thursday was 161% of its historical average. The Central Sierra snowpack was 94%. But the Southern Sierra was only 75% of average.
“Above the I-80 corridor, we got a ton of snow with those atmospheric rivers, but there is less and less as we move south,” Reising said.
Rainfall totals are even more dramatic.
Since Oct. 1, San Francisco has received 10.2 inches of rain, or 121% of normal. But Los Angeles has received virtually none at all — just 0.16 inches — over the same time, or 4% of its historical average. Sunny hot conditions have left fire risk high across Southern California through Christmas and New Year’s, even as fire season in Northern California all but ended around Thanksgiving when significant rainfall drenched the soil and vegetation.
Historically, Northern California receives more rain than Southern California, which is why nearly all of the state’s largest reservoirs were built in the north, said Jay Lund, vice director of the Center for Watershed Sciences at UC Davis. Much of that water is moved south to cities and farms through the massive systems of canals and pumps in the State Water Project and Central Valley Project.
“So far, this year is very unusual,” Lund said. “The north is unusually wet, and the south is very unusually dry.”
From a statewide water perspective, Lund noted, if one part of the state has to be dry, it’s better that it be the south.
“If you had to pick a region to be dry, you’d rather it be the south, because it doesn’t get much rain anyway, and it imports much of its water from the north,”
Lund said. “Los Angeles gets most of its water from places other than Los Angeles.”
Apart from moderate rain and snow Friday, mostly dry conditions are forecast for the next two weeks across the state.
“Extreme shifts between dry and wet conditions are continuing this winter,” said Karla Nemeth, director of the state Department of Water Resources. “If the past several years are any indication, anything could happen between now and April, and we need to be prepared.”
California has struggled with three severe droughts over the past generation: From 2007-2009, then 2012- 2016, and most recently from 2020-2022. Scientists say the warming climate is making droughts more severe, with hotter temperatures and greater fire risk. But when large atmospheric river storms barrel in from the Pacific Ocean, the warmer temperatures enable them to evaporate more water, often resulting in huge blizzards and flood risk, creating a “weather whiplash” for California and other Western states.
Many experts say given that shift, the state needs to do more to capture water in the wet years to reduce the severity of shortages during droughts. Gov.
Gavin Newsom has pushed for construction of Sites Reservoir, a $4.5 billion off-stream reservoir in rural Colusa County north of Davis that would be built in remote ranching areas, and divert some water in wet years from the Sacramento River to store for dry years.
The project, which is supported by President Joe Biden and both California senators, has secured most of its funding and survived two lawsuits from environmental groups, which say it could harm fish in the Sacramento-San Joaquin River Delta. It needs to clear one last hurdle — obtaining water rights from the State Water Resources Control Board this year — before construction can begin.