California’s Official Snow Measurement Reveals Historic Snowpack at 237% of Average

The Department of Water Resources (DWR) conducted the fourth snow survey of the season at Phillips Station, recording a snow depth of 126.5 inches and a snow water equivalent of 54 inches. This is 221 percent of the average for this location on April 3. The snow water equivalent measures the water contained in the snowpack, which is crucial for DWR’s water supply forecast. The statewide snowpack’s snow water equivalent is 61.1 inches, or 237 percent of the average for this date, according to DWR’s electronic readings from 130 snow sensors throughout the state.

DWR Director Karla Nemeth emphasized that California’s climate is becoming more extreme, as evidenced by this year’s severe storms and flooding. The state has quickly shifted from addressing drought impacts to managing flood response and snowmelt forecasting. Many communities receiving flood assistance were facing severe drought impacts just a few months ago.

This year has demonstrated that California’s flood infrastructure will continue to face climate-driven challenges in managing and storing floodwater. The April 1 result from the statewide snow sensor network is higher than any other reading since its establishment in the mid-1980s. Before the network, the 1983 April 1 statewide summary from manual snow course measurements was 227 percent of average, and the 1952 April 1 statewide summary was 237 percent of average.

Sean de Guzman, manager of DWR’s Snow Surveys and Water Supply Forecasting Unit, noted that this year’s result will be remembered as one of California’s largest snowpack years on record. Although 1952’s snow course measurements showed a similar result, fewer snow courses existed then, making comparisons difficult. This year’s snowpack is undoubtedly one of the largest California has seen since the 1950s.

Only 1952, 1969, and 1983 recorded statewide results above 200 percent of the April 1 average for California’s snow course measurements. While above average across the state this year, snowpack varies considerably by region. The Southern Sierra snowpack is currently 300 percent of its April 1 average, and the Central Sierra is at 237 percent. However, the critical Northern Sierra, where the state’s largest surface water reservoirs are located, is at 192 percent of its April 1 average.

The size and distribution of this year’s snowpack also pose severe flood risks to areas of the state, especially the Southern San Joaquin Valley. DWR’s State-Federal Flood Operations Center (FOC) supports emergency response in the Tulare Lake Basin and Lower San Joaquin River by providing flood fight specialists and longer-term advanced planning activities. The FOC and DWR’s Snow Surveys and Water Supply Forecasting Unit help local agencies plan for the spring snowmelt season using hydraulic and hydrologic modeling and snowmelt forecasts specific to the Tulare Lake Basin, informed by DWR’s snowmelt forecasting tools, including Airborne Snow Observatory (ASO) surveys.

This year’s storms have caused flooding in Pajaro and communities in Sacramento, Tulare, and Merced counties. The FOC has provided over 1.4 million sandbags, over 1 million square feet of plastic sheeting, and over 9,000 feet of reinforcing muscle wall across the state since January.

On March 24, DWR increased the forecasted State Water Project (SWP) deliveries to 75 percent, up from 35 percent in February, due to improved water supplies. Governor Newsom has rolled back some drought emergency provisions but maintained other measures to build long-term water resilience and support communities facing water supply challenges.

While winter storms have helped the snowpack and reservoirs, groundwater basins recover much slower. Many rural areas still face water supply challenges, particularly those relying on groundwater supplies that have been depleted due to prolonged drought. Long-term drought conditions in the Colorado River Basin will also continue to impact the water supply for millions of Californians. The state continues to encourage Californians to make water conservation a way of life, as fluctuations between wet and dry conditions are expected to persist in the future.

DWR conducts five media-oriented snow surveys at Phillips Station each winter near the first of each month, from January through April and, if necessary, May. Given the size of this year’s snowpack and the potential for more snow in the forecast, DWR anticipates conducting a May snow survey at Phillips Station. The tentative date for this survey is May 1.

The data from these surveys help inform water resource management decisions and provide valuable insights into the state’s water supply conditions. As climate change continues to alter California’s weather patterns, the need for accurate and timely snowpack data becomes increasingly critical. By tracking and understanding these changes, California can better adapt and respond to both droughts and floods, ensuring the long-term resilience of the state’s water resources.

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