Climate Change Vulnerability Assessments

Communities in New Hampshire are experiencing increased flooding, drought, extreme heat, variable winters, and other extreme weather events that threaten the functionality of their critical infrastructure like water and wastewater systems.

To better understand the current and future impacts of extreme weather on critical infrastructure, the New Hampshire Department of Environmental Services (NHDES) contracted Weston & Sampson to conduct water and wastewater system vulnerability assessments for 14 communities across the state.

The vulnerability assessment framework was designed to be adaptable across systems of different sizes and complexities. Its modular structure—based on exposure, sensitivity, and adaptive capacity—allows the same methodology to be applied to anything from small utilities with a few assets to large systems with more extensive infrastructure. By using regional climate projections, asset data, and standardized scoring, the framework enables consistent evaluation while remaining flexible to local conditions. Each asset was assessed based on multiple natural hazards and three planning horizons, representing the baseline, short-term, and long-term climate scenarios.

Collectively, the project identified the vulnerability of more than 300 assets and provided recommendations for adaptation measures which can build resilience and protect public health. Vulnerability assessment findings are intended to be seamlessly integrated into each community’s asset management systems, hazard mitigation plans, and capital investment planning to support informed decision making by water and wastewater utilities.