PREP Reports & Publications


This technical memorandum summarizes the completion of the calibration of a hydrodynamic model of the Great Bay Estuary System (GBES) originally started as part of the Squamscott River modeling study. The Squamscott River modeling study was discontinued when it was realized that excessive levels of algae in the Exeter wastewater lagoons discharge had a significant effect on Squamscott River water quality. Because Exeter plans to upgrade its wastewater treatment system and eliminate excessive algal levels in its effluent discharge, it was decided not to develop a hydrodynamic water quality model with Squamscott River water quality data that is so atypical and different than expected future river water quality after the Exeter wastewater treatment system upgrade. However, it was recognized that the completion of the hydrodynamic model of the GBES would provide a useful tool for the cities of Dover, Rochester, and Portsmouth to relate present and future wastewater effluent nitrogen discharges to increases in GBES nitrogen levels. The following is a brief description of the hydrodynamic model framework and calibration analysis against salinity, temperature, and tidal elevation measurements at various locations throughout the GBES. Later sections in this document summarize the application of the GBES calibrated hydrodynamic model in computing incremental nitrogen levels in the Estuary as a result of multiple effluent nitrogen scenarios.

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