Wildfires drive multi-year water quality degradation over the western United States

In the western United States, wildfires are becoming larger, more intense, and more frequent. But their impacts don’t stop with scorched landscapes; they also leave a lasting imprint on the region’s water supplies. Forested watersheds are critical sources of drinking water for millions, and when those forests burn, the resulting changes to soil and hydrology can dramatically degrade water quality for years.

An article published in Communications Earth & Environment discovered that wildfires drive long-term water quality degradation across the western U.S. Co-authored by Carollo water resources modeler Carli Brucker and researchers at the Western Water Assessment at CU Boulder, the study analyzed data from over 500 watersheds, making it one of the most comprehensive assessments of post-fire water quality impacts to date.

Multi-Year Water Quality Degradation Caused by Wildfires

The findings are striking: post-wildfire levels of organic carbon, nitrogen, phosphorus, and sediment were elevated for up to eight years after a fire event. At their peak, some of these contaminants reached levels hundreds of times greater than baseline conditions.

Among the study’s most important takeaways is how watershed characteristics influence post-fire responses. Heavily forested and urban-adjacent basins were more likely to experience sharp increases in pollutants like organic carbon and phosphorus. These insights provide a valuable framework for utilities to anticipate and plan for post-fire water quality management.

Water Utilities and Resilience Planning

The article emphasizes the importance of long-term monitoring and adaptive treatment strategies, such as enhanced sedimentation management or increased coagulant dosages, to help utilities respond effectively to wildfire-related water quality challenges.

This research is a call to action for water utilities. It provides important benchmarks for resilience planning, particularly as wildfires grow more frequent and intense in a changing climate.

Explore the full findings to understand why wildfires are a water sector issue.