Winter snowpacks are an important source of water in the West, and their size can impact fire seasons. But researchers are finding that wildfires themselves can impact snowpack.
Bright, white fresh snow has a high albedo, meaning it reflects much of the sun’s light. But wildfires, which are increasing in size and frequency, can substantially reduce the reflective power of snow for years. Blazes can also burn off the tree canopy, exposing snow to more sun.
“Following a fire, snow disappears four to 23 days earlier and melt rates increase by up to 57%,” reads the opening of a 2022 paper that University of Nevada Reno geography professor Anne Nolin co-authored. A 2023 paper she also co-authored looked at burns in California and had similar findings.
“You might have a stronger spring freshet, that pulse, you might have more of this water coming down into your streams,” she said. “You're going to have more of that black carbon actually getting washed into those streams, changing the biogeochemistry, the quality of the aquatic ecology, more sediment coming into your reservoirs. This is a lot harder to manage for, because these dams and reservoirs really aren't designed for big pulses of sediment. And also water quality is an issue.”
“That’s the sort of thing that I think managers need to understand and be flexible about and sort of design some degree of flexibility into their river management and reservoir management systems,” she added. “We are in this new world where things aren't exactly like they used to be. And so we can't necessarily depend on historical understanding to be able to manage things, especially when it comes to burned areas.”
Even without the impact of wildfires on snowpacks, Nolin said that climate change is already shrinking snow levels across the West. But with burns accelerating disappearance, “you’ve got a much longer dry season.”
“And there's a really strong correlation between the length of the snow season, especially the spring snow disappearance date, and all of these different fire parameters, like the number of fires, the size of the fires, the number of fire complexes when two fires burn together, the overall burn severity of the fire,” she added. “So all of those things are amplified when we have declining snow packs and earlier snow disappearance dates.”
This story was produced by the Mountain West News Bureau, a collaboration between Wyoming Public Media, Nevada Public Radio, Boise State Public Radio in Idaho, KUNR in Nevada, KUNC in Colorado and KANW in New Mexico, with support from affiliate stations across the region. Funding for the Mountain West News Bureau is provided in part by the Corporation for Public Broadcasting.