Latest snow survey improves water year outlook

As a result of a third snow survey, the Department of Water Resources found that snow depth and water content are at 77% of the to-date average.(Courtesy of the Department of Water Resources.)

Sierra Nevada snowpack, water content inch closer to averages as the California Department of Water Resources continues to monitor state water supply

SACRAMENTO – After a slow start at the beginning of winter, Sierra Nevada snowpack measurements are falling closer to where the California Department of Water Resources (DWR) would like them to be.

The DWR conducted its third snow survey of the season on Feb. 29 at Phillips Station, a site just south of Lake Tahoe off U.S. Highway 50, and found that snow depth and water content are at 77% of the to-date average. DWR Director Karla Nemeth said March will be a critical month for precipitation, but the outlook for the remainder of the water year is much sunnier than it was two months ago.

“No matter how the season ends, we are ready to take advantage of the water we do have to benefit communities, agriculture and the environment, and continue storing stormwater in our groundwater basins for future use,” Nemeth said.

DWR staff recorded a snow depth of 47.5 inches at Phillips Station and a water content of 18 inches, compared to a snow depth of 116.5 inches and a water content of 41.5 inches this time last year. Statewide, the average recorded water content is at 18.7 inches, compared to 45.5 inches last year.

The Phillips Station measurements are at 77% of the to-date average and 74% of the April 1 average; the statewide measurements are at 80% of the to-date average and 70% of the April 1 average.

“We always talk about the importance of that April 1 average; that’s typically in California when we see the peak of that snowpack, or (it’s) around April 1, so today’s measurements at Phillips puts us at 74% of where we’d like to be about a month from now, as compared to last year at 170%,” DWR Supervising Engineer David Rizzardo said.

Rizzardo said that there have been some “impactful storms” in the last two months, but the state still has not seen anything like it did in 2023. While snowpack is well below what it was this time last year, it is lining up with what the state saw in its 2021-2022 water year.

Looking at the statewide data is also important to getting a comprehensive understanding of water conditions throughout all of California, because snowpack levels at Phillips Station are not necessarily indicative of what they would be across the entire Sierra Nevada.

In the Central Sierra region, Rizzardo said the water content is at 77% of the to-date average and 67% of the April 1 average. In the Southern Sierra region, water content is 76% of the to-date average and 67% of the April 1 average. Comparatively, the Northern Sierra/Trinity region is at 91% of the to-date average and 80% of the April 1 average.

Rizzardo said there is “quite a bit of work to do to get up to average in the San Joaquin region.”

Snow surveys like the Phillips Station survey take place across the state on a monthly basis so that scientists can analyze and predict the amount of water that will be available to California residents and farmers during the drier months of the year.

“All this information as we allude to is extremely important into how we analyze and understand how much runoff may be coming down the hill later in the summer and fall, and that’s the snowmelt that comes from our snowpack and that is very crucial to our freshwater supply,” Rizzardo said.

Additionally, the surveys are vital to historical data gathering; the Phillips Station survey has been conducted once a month in the winter and within the same 10-day time frame since about 1910, Rizzardo said.

This is also why the DWR did not wait for the forecasted winter storm conditions to pass before conducting the survey.

“When we go measure snow, we’re not just trying to capture the effects of one storm, we are trying to gauge where we are along the season and along the water year as it progresses,” Rizzardo said.

The DWR and other agencies that participate in the California Cooperative Snow Survey will still measure the effects of the storms expected to take place at the beginning of March to record as much information as possible and capture the progression of the water year.

One more Phillips Station snow survey is scheduled for the beginning of April, and a fifth and final snow survey may be conducted at the beginning of May, depending on weather behavior throughout April.

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