Sierra Snowpack: What It Means for the Yuba River Watershed 

Recent February storms brought much-needed snow to the Sierra Nevada, but California’s snowpack remains below average for this time of year. According to the California Department of Water Resources, as of March 16, the statewide percent of normal snowpack to date was 46%. The northern region comprised largely of the Klamath Watershed is at 24%, the central region which includes the Yuba is at 47%, and the southern region including Yosemite and Kings Canyon was at 68%.   

When measuring snowpack, the reported number is Snow Water Equivalent, or SWE. SWE measures the amount of liquid water present in a volume of snow which is important because much of the snowpack is actually air. Especially when spring arrives early and is exceptionally warm, even SWE can be misleading when we think about water availability and drought. Warm temperatures mean that much of the snowpack can be “lost” to sublimation – the process by which the solid water that comprises the snowpack transitions straight to a gas (evaporates) without ever being liquid water. 

It is also worth keeping in mind that the percentage of average is in reference to a specific 30-year reference period. For most climate related impacts, the current reference period is 1990 – 2020, and it gets updated every 10 years. 

The rolling, 30-year reference period does have two interesting implications that can minimize how we perceive the impacts of climate change. First, a rolling average updated every decade means that recent large climate events like floods and droughts are incorporated into the average. By incorporating extreme weather events into the rolling average, the magnitude of deviation from “normal” appears smaller because normal is changing through time, as opposed to always comparing to a constant reference period. Secondly, using an average for something like snowpack does not necessarily accurately represent the most common amount of snow, which is commonly how average is thought of. In a system like snowpack where increasingly we see either lots of snow or very little snow, the average snowpack can actually be quite an unlikely occurrence. Using percentiles, like the graph below, provides a better understanding of how current snowpack relates to historical values. 

An Uneven Winter 

The recent February storms ended a five-week dry period that had significantly reduced snow accumulation earlier in the winter. Despite these storms being some of the coldest and best snow-producing since 2023, they were insufficient to bring conditions back to average. 

You can see that jump in the black line representing SWE this year in this graph:  

The snowpack is in better shape than one month ago, but with only about a month remaining in the snow-accumulation season and NOAA’s 90-day outlook calling for above average temperatures and below average precipitation additional snow is unlikely.  Time is rapidly running out to catch up. Statewide, the snowpack is only about 44% of where officials hope it will be by April 1, when snowpack historically peaks before transitioning to generating runoff into California’s rivers and reservoirs. 

Maps from National Weather Service Climate Prediction Center 

The Bigger Picture: Climate Change and Water Supply 

California’s water supply increasingly depends on a small number of big storms, and the dramatic wet-dry swings this winter demonstrate how warmer average temperatures have reshaped the state’s water cycle, creating higher drought risk when storms don’t arrive. 

This winter has demonstrated exactly that pattern — atmospheric rivers early in the season started to build a strong snowpack, followed by an unusually dry and warm January and beginning of February eroded those gains. The cold February storm helped build the snowpack back, but warmer rain-on-snow storms and a rapid shift to above freezing temps at night have contributed to a rapidly dropping snowpack. 

What This Means for the Yuba River Watershed 

Snowpack functions as the Sierra Nevada’s natural reservoir, storing water during winter and releasing it gradually through spring and summer when communities, agriculture, and ecosystems need it most. On average, the Sierra snowpack supplies about 30% of California’s water needs. 

Below-average snowpack means the Yuba River watershed faces potential challenges in the months ahead: 

Summer flows: Chinook salmon and steelhead populations already struggling with climate impacts need cold, clean water. Lower flows and warmer temperatures compound the challenges these threatened species face. 

Elevated fire risk: Reduced snowmelt means forests and vegetation dry out earlier and more completely, extending fire season and increasing risk to communities. 

Greater pressure on restoration investments: SYRCL’s meadow restoration projects are designed to store water and sustain flows during dry periods. In below-average snowpack years, these natural infrastructure projects become even more critical. 

Irrigation water: Agricultural customers and those with raw water service rely on consistent spring and summer flows. Less snowpack means the natural recharge period is shorter, potentially requiring earlier conservation measures. 

Recreation: Low snowpack affects reservoir levels, which determine boat launch access, swimming conditions, and summer recreation opportunities on the river and at facilities like Scotts Flat, Rollins, and other reservoirs. 

Looking Ahead 

With the prime snow-accumulation months mostly behind us, catching up to average conditions becomes increasingly difficult. SYRCL continues monitoring conditions in the Yuba River watershed and tracking how snowpack levels translate into river flows, water quality, and ecosystem health. We work year-round on projects that build watershed resilience: restoring meadows that store water, improving forest health to protect water quality, and creating habitat that helps salmon populations adapt to changing conditions. 

Climate change is reshaping California’s water cycle with more dramatic swings between wet and dry conditions. The work we do to restore natural systems and build resilience matters more than ever.