Recent storms boost state water supply according to season’s 1st snow survey

The manual survey recorded 24 inches of snow depth and a snow water equivalent of 5 inches, which is 50% of average for this location. Snow water equivalent is a measure of how much water is contained in the snowpack and is a critical component of the agency's water supply forecasts. April 1 is typically when the snowpack is at its peak each year in the mountains.

"Major reservoirs are at their top of conservation, which is at a really good place right now," Angelique Fabbiani-Leon, state hydrometeorologist with DWR, said. "Our snowpack is actually a natural reservoir, so we usually reach a peak about April 1. During that period is also when we have our highest water demand, so ideally we would like to get our snowpack to reach our April 1 average."

"While California is in a better position now, it is still early in the season and our state's water supply for this year will ultimately depend on a continued cadence of storms throughout winter and early spring," Fabbiani-Leon said.

Electronic data from more than 130 snow monitoring stations across the Sierra Nevada show a statewide snow water equivalent of 6.5 inches, which is 71% of average for this date. This compares to 115% of average at the same time last year.

Typically, the Sierra Nevada snowpack supplies about 30% of California's water needs.

Major reservoirs across California are currently at 123% of average for this time of year, bolstered by recent precipitation and three consecutive years of above-average snowpack conditions.

Groundwater, which accounts for almost 60% of the state's water supply in drought years, is under strain due to multiple dry years. According to DWR's Water Watch website, 26% of groundwater monitoring wells have water levels below average and 93 of them are reported dry.

All these measurements start on Oct. 1, the beginning of California's water year. Statewide precipitation this water year has been an average of 11.32 inches, well above the historic average of 7.7 inches.

Data from DWR's snow surveys and forecasts play a key role in guiding how the state manages its water resources. The next survey is tentatively scheduled for Feb. 3.