What a Difference a Year Makes: Huge Snowpack Raises Flooding Alarms
The state Department of Water Resources said Monday that readings from 130 snow sensors across California show the snowpack is a record-tying 237% of average for the date.
DWR conducted its fourth snow survey of the season Monday at Phillips Station near Lake Tahoe. The manual survey recorded 126.5 inches of snow depth and a snow water equivalent of 54 inches, which is 221% percent of average for the location.
“This year’s severe storms and flooding is the latest example that California’s climate is becoming more extreme,” said DWR Director Karla Nemeth in a news release. “After the driest three years on record and devastating drought impacts to communities across the state, DWR has rapidly shifted to flood response and forecasting for the upcoming snowmelt. We have provided flood assistance to many communities who just a few months ago were facing severe drought impacts.”
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Climate Change Creates Challenges for Flood Protection Systems
Just as the drought years demonstrated that California’s water system is facing new climate challenges, this year is showing how the state’s flood infrastructure will continue to face climate-driven challenges for moving and storing as much of the floodwater as possible, DWR officials said.
This year’s April 1 result from the statewide snow sensor network is higher than any reading since the snow sensor network was established in the mid-1980s. Before the network was set up, the 1983 April 1 statewide summary from manual snow course measurements was 227% of average. The 1952 April 1 statewide summary for snow course measurements was 237% of average.
“This year’s result will go down as one of the largest snowpack years on record in California,” said Sean de Guzman, manager of DWR’s Snow Surveys and Water Supply Forecasting Unit. “While 1952’s snow course measurements showed a similar result, there were fewer snow courses at that time, making it difficult to compare to today’s results. Because additional snow courses were added over the years, it is difficult to compare results accurately across the decades with precision, but this year’s snowpack is definitely one of the biggest the state has seen since the 1950s.”
Watch: March 31 Devils Postpile Snow Survey
Southern Sierra Snowpack Is 300% of Average
For California’s snow course measurements, only 1952, 1969, and 1983 recorded statewide results above 200% of the April 1 average. The Southern Sierra snowpack is currently 300% of its April 1 average and the Central Sierra is at 237% of its April 1 average. The critical Northern Sierra, where the state’s largest surface water reservoirs are located, is at 192% of its April 1 average.
The size and distribution of this year’s snowpack pose severe flood risk, especially in the Southern San Joaquin Valley. DWR’s State-Federal Flood Operations Center is supporting emergency response in the Tulare Lake Basin and Lower San Joaquin River by providing flood fight specialists to support ongoing flood response activities and by providing longer-term advanced planning activities, state officials said.