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Agreement with U.S. Government, State of New Hampshire to Yield Significant Reductions in Water Pollution from Manchester, N.H. Sewer Systems

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John Senn (
(617) 918-1019

MANCHESTER, N.H. – The U.S. Environmental Protection Agency (EPA) and the U.S. Department of Justice (DOJ) today announced an agreement with the City of Manchester that will result in significant reductions of sewage from the city's wastewater treatment systems into the Merrimack River and its tributaries. The State of New Hampshire joined the U.S. government as a co-plaintiff on this agreement, which also resolves alleged violations of the Clean Water Act by the City of Manchester.

Under a proposed consent decree filed in the U.S. District Court for the District of New Hampshire today, the City of Manchester has agreed to implement a 20-year plan to control and significantly reduce overflows of its sewer system, which will improve water quality of the Merrimack River. The plan is estimated to cost $231 million to implement. The Merrimack River is a drinking water source for more than 500,000 people, is stocked with bass and trout for fishing, is used for kayaking and boating and other recreational opportunities.

"This agreement means a healthier Merrimack River and cleaner water for the communities along the river in both New Hampshire and Massachusetts," said EPA New England Regional Administrator Dennis Deziel. "EPA has long been committed to working with our state and federal partners and cities like Manchester to improve water quality along the Merrimack, which is an important source of drinking water and recreation destination."

"This agreement demonstrates a recognition by all parties of the importance of maintaining our clean waters," said Bob Scott, Commissioner of the N.H. Department of Environmental Services. "NHDES looks forward to continuing to work with Manchester, both in terms of financing the projects and ensuring they are successful."

The settlement addresses problems with Manchester's combined sewer system, which when overwhelmed by rain and stormwater, frequently discharges raw sewage, industrial waste, nitrogen, phosphorus and polluted stormwater into the Merrimack River and its tributaries. The volume of combined sewage that overflows from the Manchester's combined sewer system is approximately 280 million gallons annually, which is approximately half of the combined sewage discharge volume from all communities to the Merrimack River.

Under the proposed consent decree, Manchester will implement combined sewer overflow (CSO) abatement controls and upgrades at its wastewater treatment facilities that are expected to reduce the city's total annual combined sewer discharge volume by approximately 74% from approximately 280 million gallons to 73 million gallons.

The two major components of the CSO abatement controls will disconnect Cemetery Brook in Manchester, the largest of the local five significant connected brooks, from the city's combined sewer system. Manchester will design and construct a new 2.5-mile drain for Cemetery Brook from Mammoth Road to the Merrimack River to convey both the brook's and storm drainage flows. The city will also design and construct projects to separate the combined sewers for areas adjacent to the Cemetery Brook drain. These drainage and sewer separation projects will together address the largest drainage basin in the city and produce the greatest volume of CSO reduction.

The work under the proposed consent decree also includes the construction of a new drain and sewer separation in the Christian Brook drainage basin, which will remove the third largest brook from the wastewater collection system.

The proposed consent decree also requires the city to implement a CSO discharge monitoring and notification program, which will include direct measurement of all discharges from six CSO outfalls estimated to be more than 99% of all of the city's total CSO discharge volumes. The city will be required to provide initial and supplemental notification to the public, including public health departments and downstream communities, with notification made through electronic means such as posting to the city's publicly available website and reasonable efforts to provide other notification.

In addition to the 20-year control plan, the proposed settlement also requires the upgrades to improve the handling of solid waste at the wastewater treatment plant to reduce discharges of phosphorous.

Many of the communities in the Merrimack River watershed are environmental justice communities with large numbers of minority and low-income residents.

In September 2019, EPA issued Clean Water Act permits to the cities of Haverhill, Lawrence and Lowell, Massachusetts under the National Pollutant Discharge Elimination System to reduce pollutant discharges from the three wastewater treatment plants and associated CSOs into the Merrimack River at 27 locations across the three cities.

The proposed consent decree is subject to a 30-day public comment period and court approval after it is published in the Federal Register. It will be available for viewing on the DOJ's website:

For more information on this settlement, visit:

For more information on EPA's work on the Merrimack, including the Agency's interactive "story map," visit:

For more information on EPA's work to address raw sewage and contaminated stormwater in communities across the country, visit: