Portsmouth, New Hampshire

Water Quality Permit Negotiations with the USEPA

Ambient Engineering was retained as a water quality and marine ecology expert by the Conservation Law Foundation (CLF) as part of negotiations with the EPA and the City of Portsmouth, New Hampshire.

Map Source: The Great Bay Stewards

The facility discharges into the Great Bay Estuary, a large and complex estuary which provides a variety of habitats.

Ambient developed and presented evidence that the Great Bay Estuary and the Piscataqua River are impacted by elevated nitrogen levels and by Total Suspended Solids deriving in part from the facility's discharges.

Photo: J. Costa

Elevated nitrogen results in a shading of eel grass beds by phytoplankton blooms and also fosters the growth of periphytic algae on the eel grass stems.  Coating of eel grass stems with algal growth or with sediments, such as those derived from WWTFs, diminishes the available light for penetration to eel grass beds.  This diminished light has been shown to correlate with decreased eel grass bed extent, and with inability for the eel grass to recolonize areas that are otherwise suitable for growth.