Drinking Water Under Fire: Water Utilities’ Vulnerability to Wildfires in the Pacific Northwest

Increased wildfire activity in the western US can lead to detrimental cascading effects to water quality. After fires, burned areas may experience significant runoff-induced erosion and sediment transport into rivers and reservoirs, which could rapidly overwhelm existing drinking water treatment plants. This paper couples an assessment of wildfire risk with an evaluation of water utility preparedness to understand where key fire-related drinking water vulnerabilities exist. Wildfire risk assessments were constructed based on existing methodologies described in the academic literature to assess fire impacts in watersheds used by water utilities. A water utility preparedness index was created for this study using publicly available information to contextualize how well utilities may be able to respond to water quality degradation after fires. Based on the available data, results indicate that roughly one-third of utilities studied (representing 12% of the population served) were underprepared for fire and one-third used watersheds at greater risk of wildfire (representing 26% of the population served). However, only four utilities (2% of the population served) were likely underprepared and at greater risk of fire. The information developed here could provide a useful framework from which utility managers can better assess their likely wildfire risk and preparation plans relative to others should a fire occur.