As fire incidents have increased, so have pollutants from burned water catchments. This was highlighted by researchers in a review paper indicating the requirement for more research in this area. The wreckage of a house and car after the Carr Fire passed through the west end of Redding, California, in 2018. Image credit: Cecilio Ricardo/USDA Forest Service Much less studied are the effects of fire that burns not only forests and grasslands, but also houses, vehicles and other man-made material. There have been only a few studies of the pollutants mobilized by these types of fires. Stephen LeDuc, Center for Public Health and Environmental Assessment, US Environmental Protection Agency LeDuc is a co-author of the new paper published in Water Resources Research, AGU’s journal for original research on the mobility and organization of Earth’s water. The paper emphasizes water trends after fires, as reported through 184 scientific papers since 1980. They found that streamflow typically increases after a fire, along with sediment and water temperature. Often, nutrients also increased, as well as some organic chemicals and toxic metals, often reaching concentrations up to 10 to 100 times higher than pre-fire levels. Some post-fire chemicals present in water, such as arsenic, can also exceed regulatory limits in treated drinking water. The report also found higher levels of the carcinogen benzene in tap water after burning homes and vehicles in Paradise, California. Scientists also found elevated concentrations of metals in the ash from these fires, which could affect runoff. The review found that little research had been conducted on the type of pollutants produced by urban fires. This has led to a disadvantage for planners and water managers recovering from a wildfire. “We point to this as a significant gap in the scientific understanding of fire impacts,” LeDuc said. In my view, the main reason for the knowledge gap is the challenge of setting up an urban water quality monitoring program in a short period of time, such as after a fire. There is plenty of interest, but at the end of the day, successful water quality monitoring efforts result from projects that are approved in a timely manner. Dennis Hallema, Hydrologist, Desert Research Institute The impact of wildfires on surrounding ecosystems was also examined in the study. The frequency of wildfires is increasing in places like the western US, in part due to climate change, and there is a potential for wildfire-burned areas to become long-term water quality stressors if previous vegetation is slow to recover or fails entirely. [But] Burned areas could be targeted for restoration efforts such as erosion control or plantings. Stephen LeDuc, Center for Public Health and Environmental Assessment, US Environmental Protection Agency A restoration effort following the 2011 Las Conchas Fire, which was reported in the paper, was undertaken by the Pueblo of Santa Clara. The researchers note that they believe their review will help communities and water quality managers plan for and recover from wildfire impacts on their water.
Journal report
Paul, MJ, et al. (2022) Fire induced changes in receiving waters: A peer-reviewed review for water quality management. Water Resources Research. doi.org/10.1029/2021WR030699. Source:
