Joint Report of Peer Review Panel for Numeric Nutrient Criteria

This Peer Review Report was commissioned jointly by the New Hampshire Department of Environmental Services (DES) and the municipalities of Dover, Portsmouth and Rochester (the Great Bay Coalition).  The four Peer Reviewers are national experts that were selected because of their expertise in nutrient impacts to estuaries, including expertise in modeling for nutrient impacts, and expertise in eelgrass biology.  The Peer Reviewers were asked to answer specific questions (jointly developed by DES and the Coalition), regarding the scientific basis for the conclusions reached in the DES report entitled “Numeric Nutrient Criteria for Great Bay Estuary” dated June 2009.  This June 2009 document interpreted the nitrogen water quality criteria for the Estuary.  This document was the basis upon which DES declared the waters of Great Bay and its contributing tributaries to be “impaired” for nitrogen because of its effects on eel grass growth in Great Bay.  This, in turn, led DES to determine that a very stringent nitrogen standard should be set for the health of Great Bay.  It also influenced the EPA determination to propose very stringent nitrogen limits in the wastewater discharge (NPDES) permits of all the treatment plants that discharge, directly or indirectly, to Great Bay, including the City of Rochester.

This Report is the culmination of the panel’s work to provide guidance to DES as well as the Great Bay communities charged with making scientifically sound decisions about what is necessary to protect the health of the tidal rivers and the Great Bay.  The Report concludes that the June 2009 document was not scientifically sound because, among other things, it failed to consider several other factors that may also be affecting the eel grass growth in Great Bay.  It recommends that additional work be undertaken, including the development of a hydrodynamic water quality model, to better define system responses and identify appropriate nutrient reduction requirements in an adaptive management framework.

Rochester and the other Coalition members are committed to its partnership with DES to develop additional data and water quality modeling to make sound nutrient criteria decisions that will protect the tidal rivers and Great Bay.  In the meantime, Rochester continues its efforts to reduce its nitrogen discharges to the Cocheco River from its wastewater treatment plant, and to date the City has made significant progress in that regard.