Critical Drivers for Wastewater Management in the Great Bay Estuary Watershed: Water Quality and Habitat Protection, and Sustainable Growth Management

Increasing population growth resulting in substantial land development is contributing to increased wastewater generation and some increased nutrient loadings to Great Bay in New Hampshire. Seventeen wastewater treatment plants discharge to the Great Bay watershed. Some of the WWTP discharges do not meet current limits and others are not able to meet future limits, which are expected to include nitrogen and phosphorus. Initial proposals for wastewater management focused on a regional centralized collection system with local or regional treatment and subsequent offshore discharge to the Gulf of Maine. While this would have allowed the communities the ability to meet effluent discharge limits, there was significant concern on the part of the communities and other stakeholders regarding the potential for extended centralized wastewater collection systems to generate secondary growth, result in significant reduction in local groundwater levels and reduced aquatic base flow in receiving waters in the project area, and transfer a water quality problem from the estuary to the Gulf of Maine. Thus, alternative wastewater management strategies were developed. These alternatives included upgrading existing WWTPs and discharging treated effluent to existing surface water discharge locations, treating wastewater locally and discharging to local land application sites, and requiring decentralized wastewater treatment and local discharge for a significant portion of all new growth. The study addresses the key concerns of reducing nutrient loading, while encouraging sustainable development and natural resource protection.