Learning Climate Resilience: Maine climate adaptation for climate resilient wastewater infrastructure

This study analyzes 21 climate adaptation plans developed by Maine wastewater treatment systems participating in the Maine Department of Environmental Protection's Climate Adaptation Planning (CAP) program between 2017-2023. The CAP program provides up to $20,000 in loan principal forgiveness through the Clean Water State Revolving Fund to support wastewater systems in identifying climate hazards and developing adaptation responses to enhance infrastructure resilience.

We extracted and categorized over 700 planned adaptation responses across four system categories: system-wide (32%), pump stations (31%), collection systems (23%), and wastewater treatment facilities (13%). Storm and flooding hazards dominated both assessed risks and planned adaptations, representing 68% of all adaptation responses, while sea level rise (6%) and temperature changes (1%) received minimal attention. The most common adaptation strategies included conducting infiltration and inflow studies, protecting electrical components, ensuring backup power, and coordinating rapid power restoration.

We created a novel Adaptation Response Index (ARI) that weighted responses by priority level, the study compared planned adaptation intensity to assessed risk levels across locations. Results showed that 75% of plans demonstrated adaptation responses proportional to risk levels, while 13% showed over-adaptation and 13% under-adaptation relative to similar risk scenarios. Coastal locations exhibited higher assessed risks and adaptation response intensities compared to inland or riverine systems.

The analysis reveals that the CAP program has successfully generated comprehensive adaptation planning, with most systems appropriately matching their response intensity to assessed risks. However, the study identifies opportunities for enhanced guidance on compound hazards, integration of future climate projections beyond current risk assessment tools, and continued peer-to-peer learning to advance resilience building efforts across Maine's wastewater infrastructure.