Informing Climate Change Risk Decision-Making for Drinking Water Utilities

Climate change hazards, including increased temperatures, drought, sea level rise, extreme precipitation, wildfires, and changes in freeze-thaw cycles, are expected to alter water availability and water quality and to degrade drinking water utility system infrastructure across the United States (US). These changes may decrease reliability of water provision and require changes in financing and operations by utilities. The extent to which climate change hazards will affect a utility’s ability to provide adequate quantity and quality of water to consumers depends on the exposure of the utility to different climate hazards and its vulnerability to those hazards. Current resources to inform decisions about climate resilience do not provide a national-level understanding of drinking water utility climate risk and are not suited for utilities looking to benchmark their climate risk against other utilities. A quantitative measure of utility climate risk is needed to understand the scale and distribution of climate risk across the national drinking water infrastructure.

This goal of this research was to apply quantitative and qualitative methods to (1) improve understanding of utility-level knowledge of climate change risks to system reliability and the status of climate adaptation planning at utilities, (2) develop a comparative drinking water utility climate risk index that quantifies risk due to projected climate change hazards and existing utility exposure and vulnerability, and (3) identify drinking water utilities in need of climate adaptation and resilience planning assistance.

Perceptions of climate change risks to drinking water utilities are not always aligned with projected risks, which vary geographically across the US. All utilities are exposed to climate change hazards, and around half of US utilities could experience large changes in one or more climate hazards that could affect an aspect of system reliability, including water resources, infrastructure, or operations. Many drinking water utility managers’ perceptions of future natural hazard risk are built from historical exposure information and tend to focus on potential climate-induced changes to water supply and infrastructure. Utility managers displayed less awareness of or concern for potential affects to operations and maintenance, water quality, or business functions. While there are utilities in every region of the US with high climate risk index values, utilities in the Western US tend to have higher projected climate change risk due to changes in climate hazards that are expected to be more significant, while utilities in the Northeast and Midwest have higher risk due to existing vulnerabilities and exposure. Few utilities have developed climate adaptation plans. Many utilities with the highest climate risk do not mention climate change in their municipal bond statements. These results indicate that drinking water utilities need guidance about climate adaptation planning and that policymakers should consider including climate hazards and projections as part of required utility risk and resilience assessments.