More Smaller Wildfires May Increase Water Resources In The West, Study Says

Nov 5, 2018

Strawberry River, upstream of Starvation Reservoir in Utah, just two months after the 2018 Dollar Ridge Fire. In addition to the threat to reservoirs, excessive sediment inputs to rivers after wildfire can dramatically alter river form, limit the recovery of stream-side vegetation, and devastate fish populations and habitat.
Credit Chris Brown, Utah State University

The land of the western United States is shaped by wildfire and water availability. According to new research from Utah State University, increasing the number of smaller wildfires could increase water resources in the West.   

"It is important to let lands periodically burn for a number of reasons, but the one that we highlight and that I think is unusual is water resources and the protection of water resources," said Brendan Murphy, a postdoctoral fellow in the Department of Watershed Sciences at Utah State University. "Increasing burned area on the landscape is actually critical for helping to protect and prolong the water resources we have here in the West."

In the western United States, most of the watersheds are dominated by forest ecosystems.

"Catastrophic fires so these big, high severity, uncontrollable fires they produce excessive amounts of sediment," Murphy said. "Effectively catastrophic fires produce catastrophic erosion, and all of that sediment makes its way into the rivers and gets carried downstream into our reservoirs, and can actually backfill our dams. And as they do that we actually lose the capacity within those reservoirs, so we are losing water storage when this happens."

Severe wildfires increase the amount of sediment entering dams and reservoirs. But according to Murphy smaller wildfires have a dramatically smaller amount of sediment input, but wildfire suppression minimizes these low severity fires.

"But by having more low severity fires you’re actually going to have less sediment going in with these wildfires and you may prevent the big one, right, the big wildfire that is going to do that catastrophic erosion. By allowing more wildfire on the landscape we can protect resources by limiting the amount of erosion and the amount of sediments making it into our dams and reservoirs," Murphy said. 

He hopes this research will serve as a warning to the western US.

"We have built a system where we are completely reliant on dams and reservoirs for water supply and that water supply is decreasing," Murphy said. "Snowpack is decreasing in the West, precipitation is decreasing in the West, the forests are getting drier, so we are seeing a decrease in the supply to those reservoirs, but we are also seeing a loss in capacity of those reservoirs, those reservoirs have a sediment lifespan." 

Access can be found here to the free, open-source paper published in Earth's Future, published by the American Geophysical Union.