Bigger, more frequent wildfires threaten water supplies across the US - CGTN
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Wildfires leave behind charred trees and scorched vegetation that can contaminate streams and rivers supplying drinking water to much of the country, with new studies showing that the contamination could persist for more than a decade.
Climate change and increasingly strong El NiΓ±o events, which intensify drought conditions, have contributed to larger and more frequent wildfires in the United States. So far in 2026, 68,179 blazes have burned more than 3.8 million hectares.
A Los Angeles County Fire Department Engine and other emergency vehicles stage near the Bryson fire on the outskirts of Malibu, California, the US, October 15, 2026. /VCG
Rain carries ash and organic matter from burned hillsides into streams supplying water treatment plants. Communities are working to adapt, but solutions can take years.
Las Vegas, New Mexico, went without water for months after the Hermit's Peak/Calf Canyon wildfire contaminated the Gallinas River in 2022. Since then, the city has provided bottled water and brought in water from nearby towns while raising funds for a new treatment plant. Karen Pettine, owner of the Hillcrest Restaurant for 50 years, said the crisis forced the business to close. Mayor David Romero said climate change has made previously reliable conditions less predictable.
Wildfires are a natural part of forest ecosystems, but their increasing severity has made watersheds β areas that capture, filter and regulate water flow β more vulnerable, said Amanda Hohner, an assistant professor at Montana State University specializing in wildfires and water quality.
Forested watersheds supply water to nearly two-thirds of US municipalities, according to Carli Brucker, lead author of a University of Colorado Boulder study comparing water quality in hundreds of burned and unburned basins. The study found that the impacts can last up to eight years.
Garrett McKay, an assistant professor of civil and environmental engineering at Texas A&M University, said utilities are seeking expert help to find alternative water sources and treat organic matter.
Wildfires cause spikes in heavy metals and dissolved organic matter that treatment plants are not designed to handle. Facilities may have to shut off incoming water and use alternative sources, including groundwater and reservoirs, which can also be affected, Brucker said.
Reservoirs can trap sediment, said Kyle Shimabuku, an assistant professor of civil engineering at Gonzaga University. However, nutrient-rich sediment from burned vegetation can promote algal blooms that make people sick and kill fish.
Organic matter also reacts with chlorine used in water treatment to form disinfection byproducts, which are regulated by the US Environmental Protection Agency because they can cause illnesses, including cancer. Treatment plants must remove organic matter before disinfecting water, potentially delaying supplies, McKay said.
After a 2020 wildfire threatened Glenwood Springs, Colorado's primary water sources, the Colorado Water Conservation Board authorized an emergency loan of $8 million within two months to improve the treatment system.
That year, ash and sediment from the Cameron Peak fire forced Fort Collins to close its river intake and draw water from Horsetooth Reservoir, which is fed by a different watershed.
Las Vegas faced more severe problems after the 2022 fire damaged the Gallinas River watershed. Heavy rains carried ash and sludge into the river and reservoirs, forcing the town to shut down its treatment plant and install additional filters.
A massive flood in 2024 brought more debris into the town's two reservoirs, leaving only a few days' worth of safe water. The town shipped in 2.2 million gallons (8.3 million liters) from Santa Fe and Santa Rosa. In February 2025, burn debris, bad weather and equipment failure caused another drop in water pressure, resulting in a monthlong boil-water advisory.
The state and federal governments allocated $148 million to rebuild the treatment plant and support alternative water sources, including drilling wells and reusing water. Groundbreaking on the first phase is scheduled for November 18, Romero said. The town is seeking alternatives because, amid climate change, it cannot depend on the Gallinas River indefinitely.
