TThe DPW’s wastewater system includes approximately 120 miles of sewers, 20 pump stations, 3 combined sewer overflows and the Peirce Island and Pease wastewater treatment facilities (WWTFs). The WWTFs are designed to protect the environment by removing pollutants. Because they discharge treated wastewater from a pipe into a waterbody (the Piscataqua River), the plants are permitted by the EPA under its National Pollutant Discharge Elimination System (NPDES). Unlike most states in the country, New Hampshire is one of only four states where EPA issues the permits rather than the local regulatory agency, the New Hampshire Department of Environmental Services (NH DES). Read more »

The City of Portsmouth Works to Implement Wastewater Improvements


The City of Portsmouth owns and operates two wastewater treatment facilities (WWTF) that must comply with separate National Pollutant Discharge Elimination System (NPDES) permits.

These permits, issued by the US Environmental Protection Agency (EPA) with concurrence of the NH Department of Environmental Services (NH DES), define how much the City has to treat the wastewater before it can be discharged to the Piscataqua River. The WWTFs are located at Pease International Tradeport and Peirce Island. The Pease facility was constructed in the 1950's as part of the construction of the Pease Air Force Base. The Peirce Island facility was built in the early 1960's. Both facilities have had upgrades throughout the years.

Aerial photo of the Pease International Tradeport WWTFAerial photo of the Peirce Island Wastewater Treatment Facility

The City and its Department of Public Works (DPW) Sewer Division are working to improve the City’s wastewater system to meet the EPA’s wastewater compliance requirements. The City is currently under a legal order (Consent Decree) from the EPA to upgrade the Peirce Island WWTF to secondary treatment. The upgrade project will be the single largest capital expense for the sewer system to date. The City was recently notified by EPA that the Peirce Island secondary treatment permit would be made more stringent by requiring nitrogen removal to 8 milligrams per liter (mg/L). Unrelated to the order, the City anticipates the draft permit for the Pease WWTF will also be more stringent and will result in significant WWTF upgrade to the Pease WWTP.

What We Are Doing Beyond Wastewater Improvements?

The City continues to work with other communities and regulators to improve the scientific understanding of the Great Bay to ensure scarce public resources are spent wisely. The City is participating in the Great Bay Municipal Coalition to assure that regulatory permit actions are supported by science that is agreed upon by all parties, not just the regulators. In 2014 the Great Bay Municipal Coalition and NH Department of Environmental Services hired four leading experts to complete a scientific peer review of the document entitled "Numeric Nutrient Criteria of the Great Bay Estuary" dated June, 2009. The "Joint Report of Peer Review Panel" can be found be clicking here.  For more information on the origins of this report see Recent Collaborative Efforts under the Regional page of this website.