California’s snowpack is double the average for May, survey finds

During the final statewide snow survey of the year, researchers at Phillips Station near Lake Tahoe recorded a snow depth of nearly five feet. That’s 241% of the May 1 average for this area. Statewide, the snow water equivalent is at 254% of average for this date. That measurement indicates how much water the snowpack contains, which is helpful to know when assessing the state’s water resources.

It’s not every year that the California Department of Water Resources conducts a fifth snow survey. David Rizzardo, manager of the department’s hydrology section, said it depends on whether there’s any snow to measure — and for the last couple years, that hasn’t been the case. 

The last time there was a measurable amount of snow in May at Phillips Station was 2020. That year, researchers measured only one and a half inches of snow. 

“These forecasts are vitally important to establishing the final numbers for… our water supply index,” Rizzardo said of April and May surveys. “And that sets the water year type for the Sacramento and San Joaquin Valley.”

Even though late-April temperatures spiked, officials say that statewide snowpack melted at a slower rate than average. That’s largely thanks to lower-than-usual temperatures in early April, coupled with cloud cover. Rizzardo called this a “mixed blessing.” 

“It would be nice to get a little bit more melt, just to trim a little bit off the top, so we don't have to cram all that melt into May and June and July,” he said. 

He said warmer days often mean more demand for irrigation in areas like the San Joaquin Valley, which means snowmelt could be directed towards something beneficial. But at the same, he said it’s important that it doesn’t all melt now. 

“It was very hot last week, above normal temperatures, so that accelerated the melt,” he said. “Had we been talking a week ago, the concern might have been, well, is this above normal [temperature] going to continue because we really don't want to see it accelerate too fast either.”

In a statement, state water department director Karla Nemeth said this year’s massive snowpack continues to pose a flood risk for communities in the San Joaquin Valley. She said snowmelt will lead to sustained high flows in both the San Joaquin River and Tulare Basins. 

Overall, it’s a tricky balance. Rizzardo said officials will be keeping an eye on the rate of snowmelt as the state heads into the summer, ensuring that flooding induced by it is mitigated whenever possible. 

Some parts of California — especially those in Southern California that depend on resources from the Colorado River Watershed — are still suffering the more acute impacts of drought. But overall, Rizzardo said the state has had a good winter of precipitation. For now, he said he’s hoping that the snow continues to melt at a rate the state can handle. 

“Mother Nature's in control,” he said. “And how is that weather going to change and what extremes might we still see – that's really going to dictate how this runoff occurs and whether it's happening at a pace that's manageable.”