The Effects of Wildfires on Drinking Water Quality in the Western United States

Wildfires can affect the provision of safe drinking water. The impacts of wildfires on drinking water quality are partly caused by alterations in vegetation, soil properties, and erosion rates, which in turn affect source water characteristics (see Abraham et al., 2017). Effects on surface waters have been observed to last as long as fifteen years post-fire in some locations (Paul et al., 2022). These changes to source waters can disrupt normal drinking water treatment practices and challenge systems with limited operational capacity or flexibility (Emelko et al., 2011; Price et al., 2017; Hohner et al., 2018). Wildfires can also cause direct damage to water conveyance infrastructure and other capital equipment (Proctor et al., 2020; Schulze and Fischer, 2021; Solomon et al, 2021). Recent work has shown that the challenges created by wildfires are associated with increases in the concentrations of certain contaminants in drinking water as well as the frequency of Safe Drinking Water Act violations (Pennino et al., 2022; Jankowski et al., 2023). However, recent studies have generally focused on a relatively small subset of contaminants and states over a shorter time horizon that excludes years of exceptional wildfire frequency after 2016. We study the impacts of wildfires on drinking water quality across the Western United States from 2000-2022 by linking a rich set of information on wildfire burn locations and severity, precise drinking water system intake locations, contaminant concentrations in drinking water, and Safe Drinking Water Act violation history in all public drinking water systems in the Western United States. Using watershed modelling techniques to characterize the extent of wildfire impact to intake catchment areas, we ask how the presence of an upstream wildfire affects drinking water quality downstream at different distances and time periods post-fire. Our analysis focuses on two types of outcomes related to drinking water quality: Safe Drinking Water Act violations and drinking water contaminant concentration levels. We include a diverse set of violation types as well as numerous drinking water contaminants such as disinfectant byproducts, nutrients, volatile organic chemicals, metals, and others. We test for heterogeneous impacts across drinking water system size and source, watershed characteristics, and states. In all models, we include a set of controls for weather, temporal, and state variation. Our research builds on a growing literature aiming to better understand the impacts of climate change on community drinking water systems.

Impact/Purpose

Wildfires can affect the provision of safe drinking water. The impacts of wildfires on drinking water quality are partly caused by alterations in vegetation, soil properties, and erosion rates, which in turn affect the characteristics of drinking water sources. Effects on surface waters have been observed to last as long as fifteen years post-fire in some locations. These changes to source waters can disrupt normal drinking water treatment practices and challenge systems with limited operational capacity or flexibility. Wildfires can also cause direct damage to water conveyance infrastructure and other capital equipment. Recent work has shown that the challenges created by wildfires are associated with increases in the concentrations of certain contaminants in drinking water as well as the frequency of Safe Drinking Water Act violations. We study the impacts of wildfires on drinking water quality across the Western United States from 2000-2022 by linking a rich set of information on wildfire burn locations and severity, precise drinking water system intake locations, contaminant concentrations in drinking water, and Safe Drinking Water Act violation history in all public drinking water systems in the Western United States. We ask how the presence of an upstream wildfire affects drinking water quality downstream at different distances and time periods post-fire. We test for impacts across drinking water system size and source, watershed characteristics, and states. Our research builds on a growing literature aiming to better understand the impacts of climate change on community drinking water systems. 

Citation

Haley, B., W. Austin, C. Wachter, J. Suter, J. Burkhardt, S. Pan, B. Parthum, AND S. Kolstoe. The Effects of Wildfires on Drinking Water Quality in the Western United States. Social Cost of Water Pollution Workshop, Washington, DC, October 02 - 04, 2024.