Department of Water Resources conducts third snow survey of the year, Southern Sierra snowpack reads 209% of its April 1 average
TULARE COUNTY – As California sees unprecedented amounts of rain, snowpack levels for the central and southern sierra regions look healthy, however groundwater recharge levels are still hurting.
The Department of Water Resources (DWR) conducted their third snow survey of the year on March 3 and the report showed snowpack levels are the highest they have been in years. DWR’s electronic readings from 130 snow sensors placed throughout the state indicate the statewide snowpack’s snow water equivalent is 44.7 inches, or 190 percent of average for this date. Additionally the Tulare Lake Basin precipitation levels have currently out performed the 1991-2020 average as well as the last wet year in 2018-2019. However, groundwater recharge continues to be an issue for the Central Valley and despite the amount of rain and snowfall the state has seen, the drought is immediately over.
“Thankfully the recent storms combined with the January atmospheric rivers have contributed to an above-average snowpack that will help fill some of the state’s reservoirs and maximize groundwater recharge efforts,” DWR director Karla Nemeth said. “It will also take more than one good year to begin recovery of the state’s groundwater basins.”
Each year DWR conducts about five snow surveys from January through April and sometimes May. After this month, the statewide snowpack is currently just behind the record snow year of 1982-83. However, the snowpack levels vary considerably by region. The southern Sierra snowpack is currently 209% of its April 1 average, the central Sierra is at 175% of its April 1 average. However, the critical northern Sierra, where the state’s largest surface water reservoirs are located, is at 136% of its April 1 average. The southern and central areas have about two years worth of snowpack as of the beginning of March. And according to DWR supervising engineer David Rizzardo, the central and southern areas have no cause for concern when it comes to severe snowmelt.
“We’re not expecting those entire watersheds to suddenly see a bunch of the snow all the way up to the top melt off,” Rizzardo said. “The snow is extremely cold and therefore it’s going to take a heck of a lot of energy that typically is going to come in late April, May or even June to melt some of that snowpack.”
To ensure water supply managers have the most current forecasts of snowpack runoff, DWR is utilizing Airborne Snow Observatory (ASO) technology to collect the most accurate snow measurements. DWR’s Snow Surveys and Water Supply Forecasting Unit is utilizing ASO surveys across 12 of California’s major snow-producing watersheds. Through this technology they will collect data on the snowpack’s density, depth, reflectiveness and other factors down to a 3-meter resolution. Rizzardo said they are able to see the most dense areas of the snowpack and differentiate the likelihood of melt through.
With one month of the traditional wet season remaining, DWR is providing updated runoff forecasts to water managers according to a DWR statement. They are closely monitoring spring runoff scenarios and river flows to ensure the most water supply benefits from this year’s snowpack while balancing the need for flood control.
“The recent storms over the past week broke a month-long dry spell in a dramatic way,” DWR’s Snow Surveys and Water Supply Forecasting Unit Manager Sean de Guzman said in the statement. “We are hopeful that we will see more cold storms to add to our snowpack for the next month and help set up a long, slow melt period into spring.”
While winter storms have helped the snowpack and reservoirs, groundwater basins are much slower to recover. Many rural areas are still experiencing water supply challenges, especially communities that rely on groundwater supplies, like the Central Valley, which have been depleted due to prolonged drought. It will take more than a single wet year for groundwater levels to substantially improve at a statewide scale according to the release. Drought impacts also vary by location and drought recovery will need to be evaluated on a regional scale and will depend on local water supply conditions.
“While this one wet year is great, it’s not going to recover that storage that we have lost frankly over more than a decade of dry years in the recent past,” Jeanie Jones DWR Interstate Resources Manager said.
As the last three water years were dry, it has resulted in storage deficits in reservoirs and groundwater basins according to Jones. However, with the amount of snowpack that has been recorded this year, the different water projects can look for a possible growth in allocations. Currently the two largest water projects include the State Water Project as well as the Central Valley Project according to Jones. She said they are both currently looking at 35% allocations, but of course that could change.
“We have areas like the Central Valley and San Joaquin Valley in particular, where there is really just a massive deficit and storage over a long period of time in groundwater basins and this is not something that’s going to change in any kind of rapid fashion,” Jones said.
These forecasts created by the ASO and other technologies are used to develop the Bulletin 120 for forecasted spring run-off. It then determines water allocations and stream flows for the benefit of the environment. The ASO flights utilize LiDAR and imaging spectrometer technology and have the ability to provide DWR with more information on water content than before. That information is then fed into advanced physically based and spatially explicit models to generate the most accurate water supply runoff forecasts possible according to a release from DWR.
This year, there was a stark change in prediction after the start of the year. In December 2022, early projections for the rest of the water year were showing a fourth year of drought, however when January came around the narrative changed. According to climatologist Michael Anderson, California experienced nine atmospheric rivers in three weeks in January. Of those nine, one was of the exceptional category, four were categorized as strong and four were moderate. In water years 2020 and 2021, California only saw three strong atmospheric rivers total.
Anderson explained the Climate Prediction Center (CPC) expects cooler than average temperatures throughout the state and wetter than average conditions north of Monterey Bay. He said with these sort of dramatic weather events, it is interesting to see what the CPC chooses to predict for the month.
At the state level, on Feb. 13, Gov. Gavin Newsom issued an Executive Order directing state agencies to review and provide recommendations on the state’s drought response actions by the end of April, including the possibility of terminating specific emergency provisions that are no longer needed, once there is greater clarity about the hydrologic conditions this year. According to DWR, Californians should still continue to use water wisely so that we can have a thriving economy, community, and environment. DWR encourages Californians to visit SaveOurWater.com for water saving tips and information as more swings between wet and dry conditions will continue in the future.