Sacramento, CA –- The results of the most significant snowpack measurements of the water year are in. While the news is good, officials warn it brings some spring flooding risks.
The Department of Water Resources (DWR) on Tuesday conducted the fourth Phillips Station manual snow survey of 2019. It recorded 106.5 inches of snow depth and a snow water equivalent (SWE) of 51 inches, which is 200 percent of average for that location. Officials report that statewide, the Sierra Nevada snowpack is 162 percent of average.
Since the beginning of the water year last Oct. 1, California has experienced more than 30 atmospheric rivers with six falling in February alone. In fact, the statewide snow water equivalent has nearly tripled since Feb. 1. SWE, the depth of water that theoretically would result if the entire snowpack melted instantaneously, is a key measurement water managers use across the state to estimate anticipated spring runoff.
“With full reservoirs and a dense snowpack, this year is practically a California water supply dream,” DWR Director Karla Nemeth comments. “However, we know our long-term water supply reliability cannot rely on annual snowpack alone. It will take an all-of-the-above approach to build resiliency for the future.” On average, the Sierra snowpack supplies nearly a third of the state’s annual water needs as it melts into streams and reservoirs in the spring and early summer.
The snowpack’s water content typically peaks around April 1 after which the sun’s higher position in the sky begins to accelerate snow melt. “With great water supply benefits comes some risk,” explains Jon Ericson, DWR chief of the Division of Flood Management. “Based on snowpack numbers, we have the potential for some minor flooding due to melting snow so we remind folks to always stay vigilant and aware.”
The state’s largest six reservoirs currently hold between 106 percent (Oroville) and 132 percent (New Melones) of their historical averages for this date. Lake Shasta, California’s largest surface reservoir, is 109 percent of its historical average.
DWR notes that it conducts up to five snow surveys each winter – near the first of January, February, March, April and, if necessary, May – at Phillips Station in the Sierra Nevada just off Highway 50 near Sierra-at-Tahoe. The location is one of hundreds surveyed manually; the measurements augmenting ongoing electronic readings from about 100 snow pillows in the Sierra Nevada.