Wildfire Induces Changes in Receiving Waters: A Review With Considerations for Water Quality Management
Wildland fires have increased in frequency and area burned globally. These fires produce pollutants that affect human health and environmental quality, including water quality. Despite this, water quality program managers lack information to anticipate and react to wildfire impacts. We reviewed scientific literature to assess wildland fire effects on endpoints, pathways and modifying factors of a conceptual model linking wildfire to water quality endpoints, specifically quantifying response directionality, magnitude, and duration. We included all extracted information in a searchable spreadsheet. Physically, water temperature, sediment load and water yield increased post-fire, the latter two leading to long-term channel changes. Chemically, nutrients, ions, organic chemicals, and metals increased in wildfire-impacted watersheds, sometimes by orders of magnitude. Dissolved organic carbon and nitrogen peaked with medium severity fires and increased the risk for disinfection byproduct formation. Biological assemblages commonly declined after post-fire runoff events. Effect duration was longest for channel adjustment, sediments and some nutrients (>10y), and shorter for some metals (<5y). Important knowledge gaps included pollutant generation from wildland urban interface (WUI) fires. WUI fires have the potential to mobilize suites of chemicals from burning infrastructure and directly affect drinking water, yet there have been very few studies on the topic. Other gaps include effects on lakes and wetlands and the importance of wildfire severity and return frequency on pollutant load. This review provides a resource for understanding wildfire impacts on a range of water quality endpoints, helping water quality managers and decision makers prepare for and respond to this growing problem.