"Historic wildfires raging from California to Colorado are weakening watersheds and setting the stage for deadly mudslides and flooding and, in some places, threatening to poison critical water supplies.
Fueled by record-setting temperatures and strong winds, blazes are wreaking havoc in the West, decimating entire towns like Malden in eastern Washington state, where 80% of the homes and structures — from the fire station to city hall — were burned to the ground.
But the fires don't just pose a threat to things that burn. More intense and larger fires are also shifting the very ground in Western states. Severe wildfires can change the hydrologic response of a watershed so quickly that even a relatively modest rainstorm can trigger flash floods and steep terrain debris flows, said Jason Kean, a research hydrologist with the U.S. Geological Survey's Landslide Hazards Program in Golden, Colo."