Low snowpack, higher temperatures cause concern for Bay Area scientists, farmers

While growers across the North Bay welcomed the February rains, scientists have said more rain and snow in the higher elevations in March will be crucial to preserving water resources across the state amid an unusually warm winter.

Back-to-back storms in December moving into the new year helped increase volume, and statewide water storage levels as of March 1 indicate most reservoirs are between 70-80% full, according to the California Department of Water Resources (DWR).

However, rainfall and snowstorms in March will be crucial for improving the season’s outlook, according to watershed scientists. The March 1 Philips Station measurement found that snowpack measured 47% on average for March and 45% of the April 1 average. Statewide the snowpack stood at 66% of average.

“Although the storms we saw in mid-February were some of the coldest and best snow-producing storms we have seen since 2023, they were not enough to get us back to average conditions,” said Andy Reising, manager of DWR’s Snow Surveys and Water Supply Forecasting Unit. “The snowpack is in better shape than it was one month ago, but we only have a month left of our snow-accumulation season and time is rapidly running out to catch up.”

Snowmelt  from the Sierra Nevada accounts for approximately 30% of the state’s annual water supply. Agriculture draws about 40% of the state’s total water use, according to the DWR.

Sonoma County Farm Bureau executive director Dayna Ghirardelli said February’s rainfall has been good for local agriculture.

“With it will come tremendous pastures for our dairy and livestock,” Ghirardelli said. “Early rains are always a great sign. The fact that January was so dry is troublesome, but there’s still time in the season left. Ideally we get a few weeks of dry weather with sun to put the animals out, and then a few weeks later it rains.”

Bureau President Pat Burns agreed, saying “Rains have not been a problem, at least for vineyards. We are a little below average, but not much and assume we will still get some more.”

“We are always worried about water,” Burns added.

State water scientists, while echoing their hopes for the season, flagged the lack of snow for the first two months of the year combined with higher than normal February temperatures. Temperatures Feb. 27 in the North Bay climbed into the low 80s as San Francisco Airport recorded a high of 74 degrees Feb. 28, according to the National Weather Service.

Water storage experts are waiting until next month to determine the water year outlook, said Samuel Sandoval Solís, UC Davis’s Agriculture and Natural Resources Cooperative Extension Specialist in Water Resources.

“Some of this week, we have had to leave empty (reservoir) space for floods,” he said. “Some of that water, we’re letting it flow, which I think is good. A lot of the water goes into the (Sacramento) Delta, so it keeps the salinity down.”

Solís offered the reminder that snowmelt flowing into the water system earlier drives growth of grasslands and brush, creating more fire fuels.

“By the time we hit the spring, we will have high grasses,” Solís said. “So if we have a fire event, that could be devastating.” That risk is higher for growers with less access to fuel mitigation such as cattle grazing, and some growers in Petaluma and Ukiah may be seeing “waist high” cover crops which must be managed, he added.

“It’s never too early to be proactive about this,” Solís said. “I think it’s good what is there, and rain in every part of the state counts. That’s why we say, use the water you need, but not a drop more.’’

Thomas Harter, professor in cooperative extension at Agriculture and Natural Resources, said less snowpack during a warmer year will impact agricultural water users “in a big way.”

“For a lot of folks that have the ability to use groundwater, that will be the fallback and it’ll be a stress test on the groundwater system this year,” Harter said. “If we don’t get that rain in March they will be looking at how they will compensate for that water with pumping.”

While Harter said Northern California has fared better in terms of rain than the southern Central Valley, which follows historic trends, the entire statewide water system is affected.

“The snowpack can come and go very fast,” he said. “Going into a dry cycle would not be unusual at this point. We’re not in the middle of a longer drought episode yet, but we’ll see if a ‘miracle March’ happens.”