Drinking water under fire: Water utilities' vulnerability to wildfires in the Pacific Northwest

Increased wildfire activity in the western United States 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 and expanded from a commonly used methodology co-developed between researchers and water managers (Edel et al., 2002), to understand drinking water impacts on water quality after wildfires. 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. Results indicate that 22% of utilities studied (10% of the population served) were underprepared for fire and 11% of watersheds used were at greater risk of wildfire (9% of the population served). However, nearly three-quarters of utilities (76% of the population served) showed a moderate risk of fire and some need for improved fire preparedness. Information developed here could provide a useful framework from which utility managers can better assess their likely wildfire risk and preparation plans.