Department of Water Resources is lukewarm on wet winter

The Department of Water Resources releases a statement that tempers expectations on a wet winter despite a stormy December

SACRAMENTO – Late December storms have given way to clear skies and a beautiful snowcapped mountain view. But the state’s Department of Water Resources is tepid on how much those storms helped solve California’s drought.

DWR’s Dec. 30 manual survey recorded 78.5 inches of snow depth and a snow water equivalent of 20 inches, which is 202% of average for the location on Dec. 30. The snow water equivalent measures the amount of water contained in the snowpack and is a key component of DWR’s water supply forecast. Statewide the snowpack is 160% of average for this date.

“We could not have asked for a better December in terms of Sierra snow and rain,” DWR director Karla Nemeth said. “But Californians need to be aware that even these big storms may not refill our major reservoirs during the next few months. We need more storms and average temperatures this winter and spring, and we can’t be sure it’s coming. So, it’s important that we continue to do our part to keep conserving – we will need that water this summer.”

December was the first of the three typically wettest months of California’s water year. Significant January and February precipitation would be required to generate enough runoff to make up for the previous two winters that were California’s fifth- and second-driest water years on record.

On average, the Sierra snowpack supplies about 30% of California’s water needs and the snowpack is an important factor in determining how DWR manages the state’s water resources. Its natural ability to store water is why the Sierra snowpack is often referred to as California’s “frozen reservoir.” However, DWR says significant climate changes have dramatically reduced the snow pack.

“California continues to experience evidence of climate change with bigger swings between wet and dry years and even extreme variability within a season. A wet start to the year doesn’t mean this year will end up above average once it’s all said and done,” Sean de Guzman, manager of DWR’s Snow Surveys and Water Supply Forecasting Unit said.

The department states that Californians only need to look to last winter and the state’s disappointing snowpack runoff due to high temperatures, dry soil and evaporation as a reminder that changes to climate mean it will take more than an average year to recover from drought.

As spring sets in, the snowpack begins to melt. Water that is not absorbed into the ground, called “runoff,” trickles into mountain streams, which feed rivers and eventually aqueducts and reservoirs, where it can be stored for use throughout the dry season. Climate change is affecting California’s snowpack, as more precipitation falls as rain and less as snow. Excessively dry soils and dry, warm spring temperatures are also reducing yearly runoff.

Even more DWR sites previous wet Decembers that disappear for the remainder of the season. In 2013, the first snow survey provided promising results after a wet December, similar to this year. However, the following January and February were exceptionally dry, and the year ended as the driest on record, contributing to a record-breaking drought.

Moving forward DWR states that they are trying to adjust to climate changes by investing in partnerships and implementing emerging and proven technologies to improve forecasts of precipitation, seasonal snowpack and runoff to support more efficient water management now and to help estimate the impacts of climate change on future flood and drought conditions. Forecast improvements and monitoring enhancements increase the reliability of data used to inform water managers about flood risks, allowing opportunities to create more storage in reservoirs ahead of big storms while also ensuring water supply reliability in periods of dry or drought conditions.

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.

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