Wildfires are leaving behind charred landscapes that contaminate U.S. water supplies with ash and organic matter, with studies indicating that these impacts can persist for over a decade. This growing threat to drinking water is exacerbated by climate change and intensified El Niño weather events, which contribute to larger and more frequent wildfires. So far in 2026, 68,179 fires have burned over 9.5 million acres nationwide.
After a wildfire, rain washes ash and debris into streams and rivers that supply municipal water treatment plants. Communities are struggling to adapt, often relying on temporary solutions as they fund long-term repairs. The City of Las Vegas, New Mexico, experienced a severe water crisis following the 2022 Hermit’s Peak/Calf Canyon wildfire, which contaminated the Gallinas River. For months, residents received bottled water, and water was shipped in from neighboring towns as the city worked to fund and build a new treatment plant.
“It’s hard to run a restaurant without good water,” said Karen Pettine, owner of the Hillcrest Restaurant in Las Vegas, New Mexico, describing how the water shortage forced closures and a reliance on paper products and extensive bottled water deliveries. "The water situation is ongoing because when it rains, it floods and it brings dirty water down the stream."
Mayor David Romero of Las Vegas, New Mexico, noted that climate change has reduced the predictability of previously reliable resources. "It’s a scary situation that we’re all going to encounter,” he stated.
Forest watersheds, which naturally filter and regulate water, are becoming increasingly vulnerable due to the heightened severity of wildfires, according to Amanda Hohner, an assistant professor at Montana State University specializing in wildfires and water quality. These forested watersheds provide water to approximately two-thirds of U.S. municipalities.
A University of Colorado Boulder study found that the effects of wildfires on water quality can last up to eight years. "Utilities are extremely concerned about the impacts wildfires have on water," said Garrett McKay, an assistant professor of civil and environmental engineering at Texas A&M University. Experts are being consulted to find alternative water sources or develop methods to treat the increased organic matter entering treatment plants.
Standard water treatment facilities are designed for high-quality water filtered by natural forest ecosystems. Wildfires introduce heavy metals and dissolved organic matter that these plants are not equipped to handle, according to Carli Brucker, lead author of the Colorado study. This can necessitate shutting down intakes and seeking alternative sources, which may not always be readily available, even if groundwater or reservoir backups exist, as these can also be affected.
Reservoirs, which can act as sedimentation basins, can also become problematic. Sediments from burned vegetation are nutrient-rich, potentially leading to algal blooms in still water, which can harm aquatic life and pose health risks. Furthermore, chlorine used for disinfection reacts with wildfire-induced organic matter to form disinfection byproducts, regulated by the EPA due to potential health risks, including cancer. Treatment plants must remove this organic matter before disinfection, causing potential delays in water supply.
Glenwood Springs, Colorado, faced challenges in 2020 when fires near its primary water sources, No Name and Grizzly creeks, prompted emergency funding for treatment system improvements. Fort Collins also rerouted water from a different watershed during the same year due to ash and sediment from the Cameron Peak fire affecting its river intake.
Las Vegas, New Mexico, faced repeated crises. After the 2022 fire, a significant rainstorm washed burn scar debris into the river and reservoirs, forcing a shutdown of the water treatment plant. A flood in 2024 carried more debris, leaving the town with limited safe water and requiring millions of gallons to be trucked in from nearby communities. Further issues arose in February 2025 due to burn scar debris, adverse weather, and equipment failure, leading to a monthlong boil-water advisory and additional water shipments.
"The February event was probably the scariest,” Romero said. State and federal governments have allocated $148 million to rebuild the town's treatment plant and support efforts to secure new water sources. Groundbreaking for the first phase of the new plant is scheduled for November 18. "We know with climate change and what we experienced in the past, the Gallinas River is something we can’t depend on forever,” Romero added.