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Merrimack (Upper) River Watershed Assessment Study

The Upper Merrimack River Watershed Assessment Study is a jointly funded effort between local communities, state, and Federal partners. Partners include: the New Hampshire Department of Environmental Services, the U. S. Army Corps of Engineers, New England District, the Environmental Protection Agency (which is providing technical assistance) and the Southern New Hampshire Planning Commission (which is providing facilitation and management assistance).

This study is authorized by Section 729 of Water Resources Development Act (WRDA) of 1986 entitled “Study of Water Resources Needs of River Basins and Regions” as amended by Section 202 of WRDA 2000 and by Section 437 of WRDA 2000 entitled "Merrimack River Basin, Massachusetts and New Hampshire.”

The Merrimack River is formed by the confluence of the Pemigewasset and Winnipesaukee Rivers in Franklin, New Hampshire. The River flows southward in NH and turns at the NH-MA border and flows in a northeasterly direction discharging to the Atlantic Ocean at Newburyport, MA. The watershed is about is 5,010 square miles and about 3,900 square miles are in NH.

The study area for the Upper Merrimack and Pemigewasset River Study is the mainstem Pemigewasset (54 miles) and the Merrimack River in NH (66 miles). There is an additional 50 miles of river in MA not specifically modeled as part of the NH study. Six dams are included in the study area:

  • Ayers Island Dam in Bristol/New Hampton
  • Franklin Falls Dam in Franklin
  • Eastman Falls Dam in Franklin
  • Garvins Falls Dam in Concord/Bow
  • Hooksett Dam in Hooksett
  • Amoskeag Dam in Manchester

Franklin Falls Dam is owned and operated by USACE and is used primarily for flood control purposes while the other dams are owned and operated by Public Service Company of New Hampshire and are used for hydroelectric power generation.

The study includes sampling and analysis of water quality and river flows and development of a computer model capable of assessing existing and future water quality conditions. The three major components of the model are: watershed runoff and loading, hydraulic routing, and water quality simulation.

The models are being calibrated with data collected as part of the study and other available data.

For more information, please contact the Project Manager, by email.