This article was originally published by High Country News. Two Septembers ago, the residents of Grotto, Washington, woke to the Bolt Creek Fire ripping through the mountains above their homes. “This doesn’t happen here,” Patricia Vasquez remembers saying at the time, shocked. Though areas east of the state’s Cascade mountains frequently burn in the summer, Grotto is on the mountains’ western side, in a wetter climate, where fires had been infrequent but are becoming more common. Vasquez evacuated with her husband, Lorenzo; their dog, Ava; and the fresh Alaska halibut they’d just caught while on vacation. Elizabeth Walther, their neighbor, evacuated with a puppy, but her husband, Richard, a ski patroller, stayed behind to hose down the house. No one died, and no houses burned. But wildfire survivors in Washington now face a new threat: debris flows. Wildfires can lessen the soil’s ability to absorb water, so when thunderstorms, rapid snowmelt, atmospheric rivers, or rain falling on snow occur in a burned area, that can create a roaring earthen river. Debris flows can move quickly—30 …