Worsening Wildfires Pose Profound Risks to Water Resources Across the West

Policymakers Can Take Actions to Protect our Vulnerable Water Supply

Published Jun 7, 2022

Oakland, Calif. (June 7, 2022)—More frequent and severe wildfires across the Western United States threaten the quality and availability of water for millions of people—a risk that is underappreciated by policymakers, according to a new report by the Union of Concerned Scientists (UCS).

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Local, state, and federal actions can help to minimize the impacts of wildfires on the West’s already limited water resources by reducing heat-trapping emissions, actively managing forests, and investing in climate-resilient water infrastructure, according to the analysis of scientific research and evidence from wildfire-prone regions around the world.

While large, severe wildfires visibly harm air quality, infrastructure, and landscapes, they also damage the ecosystems of watersheds by killing vegetation and altering the soil. This can result in a series of “cascading disasters,” according to the report, which includes flooding, landslides, and debris flows during heavy rainfalls following a burn as well as changes in the amount of water in groundwater reservoirs relied on—particularly in California—for drinking water and agriculture.

“As people continue to move into and build communities in forested areas, the burning of cars, homes, and other infrastructure during wildfires releases toxic compounds that can contaminate water supplies,” writes UCS Fellow Carly Phillips and Kristina Dahl, principal climate scientist for the UCS Climate and Energy Program. “Across the United States, public drinking water systems downstream of large wildfires have experienced high concentrations of compounds such as nitrates and arsenic, which, in some cases, have risen above levels considered safe by the Safe Drinking Water Act.”

The report notes that large. severe fires are projected to continue due to human-caused climate change without a rapid reduction in heat-trapping emissions. In the meantime, it recommends actions to reduce wildfire severity and protect water supplies by removing excess vegetation in forests through thinning and controlled burns, timber removal and replanting after fires to reduce erosion and decrease runoff, and burying power lines if done as part of a holistic approach that addresses forest conditions, climate change and grid resilience. On a local level, the report suggests adaptation measures to strengthen the resilience of water infrastructure that include diversifying water sources and investing in flexible treatment capacity and water-quality monitoring.

“We must make these changes in the Western United States to prepare our water systems for a changing climate and its projected impacts, particularly in California, Colorado, Oregon, and Washington, where wildfires in recent years have underscored the vulnerability of our forests and water supplies,” the authors write. “If we do not limit human-caused climate change and adapt to escalating wildfire incidence and severity, water supplies across the West will continue to be at increasing risk into the future.”