The storms early in the rainy season mean California’s water supplies are in better shape now than last year, said state climatologist Michael Anderson. Nearly the entire state is in moderate drought, with about two-thirds in severe drought. But if precipitation totals hold, he expects this year to round out the driest three years on record — even drier than the three-year span between 2013 and 2015 during the last record-breaking drought.
“The challenge is, this is year three of the drought rather than year two,” Anderson said. “And in terms of a three-year period, we’re likely going to set a new record for a three-year window of drought.”
The snowpack, too, hasn’t increased. A critical water supply, the Sierra Nevada snowpack was measured at 72% of normal for Feb. 15, but only 55% of the seasonal average measured on April 1. And in parts of the state, the snow is already melting.
“You’re in this window where you’re still expecting to be building (snow)pack, but it’s already starting to melt,” Anderson said. “The challenge will be how much snowpack makes it to spring, and how much shows up in the reservoirs.”
Anderson is keeping an eye on the months ahead, and hopes that March will bring more rain and snow than anticipated. A big question will be how much runoff from snow melt in the Sierra Nevada will reach California’s reservoirs, which saw substantially less runoff than expected last year.
“The good news is there’s room in the reservoirs to capture what does make it to the streams and come down,” he said. “The challenge is that if we’re dry this early, the demands for water start earlier.”
Most of the state’s reservoirs are sitting below historic averages despite the December deluge, with some notable exceptions, such as Folsom Reservoir — “the breadwinner of the storms,” Michael Macon, who works with the water board’s Division of Water Rights, said Tuesday.
Lake Shasta is about half a million acre-feet — enough to supply 1.5 million households for one year — short of where it stood last year. Oroville has climbed above last year’s levels, but the amount of water flowing out is starting to match water flowing in following a dry January, Macon said.
Looking ahead, Anderson says it’s a matter of waiting and watching whether spring brings more rain and snow, and how quickly summer heats up.
“The challenge then becomes, well, what does summer look like? Does it heat up really fast? Do we end up with a lot of heat waves?” he said. “Or do we get a little bit of a break with some cooler weather?”