New research from the University of Washington shows that active forest management can strengthen water security. In a study published in Frontiers in Forests and Global Change, researchers examined how forest thinning affects snowpack in the eastern Cascade Mountains.
Snowpack serves as a natural reservoir, releasing water into rivers and streams that supply farms, fish habitat, and communities throughout the region.
.jpg)
On treated north-facing slopes, thinning increased snowpack by up to 30 percent. On the south-facing slopes, snowpack increased by 16 percent. That equates to an estimated 12.3 acre feet of additional water per 100 acres on north slopes and 5.1 acre feet per 100 acres on south slopes, or millions of gallons stored naturally in mountain forests.
Dense canopies intercept snowfall, and some moisture evaporates before reaching the ground. Thinning allows more snow to accumulate and persist through winter.
The implications extend well beyond the study site. In the Yakima River Basin, snowmelt provides a large share of irrigation water, municipal supply, and instream flows for fish.
Even modest gains in snow retention at the forest level can deliver measurable downstream benefits. Researchers also found that forest structure matters. Strategic spacing and canopy gaps, which can be achieved through active management, were linked to greater snow accumulation, offering practical guidance for managers designing treatments in similar landscapes.
As snowpacks decline and drought cycles intensify, forest management decisions will play a meaningful role in shaping the reliability of Western water supplies. -Nick Smith
