Understanding Sierra Nevada Snowmelt
- February 5, 2020 -

During our winter programs, hundreds of students come to Donner Summit to study the snow-covered slopes in many different ways. We’re grateful for the opportunity to help these students understand that snowpack and snowmelt not only impact us in winter, but have a much larger impact overall.

Did you know that melting Sierra snow provides between 1/3 and 1/2 of California’s water supply? We wanted to share with you some of the resources our students use to understand how snowmelt impacts us.

Article: Why We Can’t Stop Talking About California’s Sierra Snowpack

Satellite Images of Crowley Lake before and after a major snowstorm in January 2019

Here’s an excerpt from this article:

Most of California’s precipitation comes during the cold, wet season when the crops and forests don’t need as much water,” Bales explains. He notes that farmers use 80 percent of the state’s water supply. “[They] need a lot of water in the summer, when there’s very little or no precipitation.”

And that’s where the snow comes in. Its natural ability to store water is why the Sierra snowpack is often referred to as California’s “frozen reservoir.” As spring sets in, the snowpack begins to melt. Water that’s 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.

So timing is everything when it comes to the melting of the snowpack.

“We want the runoff to be as late as possible, as close to when we need it as possible,” Bales says.

Typically, that runoff begins in April, and in wet years, it can continue to flow through August, according to Bales. But in years with less precipitation, and therefore less accumulation of snow, the runoff can wind down as early as May. That leaves farmers with less reserves for those dry summer months.

For more, read the full text of this article from KQED Science.

Video: Sierra Nevada Snowpack & Snowmelt

Here’s a video we use to help students understand California’s water supply as it relates to snowmelt.