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New Hampshire Department of Environmental Services

Designated Rivers
Lower Merrimack River

II. The Lower Merrimack River Nomination

A. Description

The Lower Merrimack River begins at the Merrimack-Bedford town line and flows for 15 miles through the communities of Merrimack, Litchfield, Hudson, and Nashua before entering the State of Massachusetts (see map). The segment is part of the larger Merrimack River system which bisects the lower third of New Hampshire and drains a 5,014 square mile watershed extending from the White Mountain region to east-central Massachusetts. Important tributaries to the Lower Merrimack River include the Souhegan and Nashua Rivers.

The Lower Merrimack River flows through a region of rapid population growth and development that is heavily influenced by the Boston metropolitan area. Land use along the river has developed in a manner that is markedly different among the four river communities. A railroad line west of the river has led to the use of the river corridor for industrial development in Merrimack and Nashua, while land use near the river in Litchfield and Hudson has remained primarily agricultural and residential. The river shoreline itself is forested and remarkably undeveloped in all four communities, however, increasing pressure to develop the river corridor is evidenced by an increase in residential development proposals before local planning boards. In cooperation with all four river communities, the Nashua Regional Planning Commission has prepared a management plan to address the use and conservation of the river corridor and is working with all of the communities to implement the plan's recommendations.

B. River Values and Characteristics

The Rivers Management and Protection Program Act (RSA Ch. 483) lists nine resource values and characteristics which may qualify a river for designation into the program. The Lower Merrimack River supports many of these natural, managed, cultural, and recreational resource values and characteristics at a level of either statewide or local significance. The resource values which qualify the Lower Merrimack River for designation include: wildlife, plant, and fish resources; scenic values; water withdrawals; wastewater discharges; historic and archaeological resources; community resources; and recreational resources.

1. Natural Resources

a. Wildlife and Plant Resources: In a region of rapid land development, the Lower Merrimack River is a safe haven of critical habitat for a variety of plant and animal species, including the federally-endangered bald eagle. The river corridor provides the necessary elements of eagle wintering habitat: perch or roost sites and open waters for fishing. Perch sites - large open branched trees - on the river's bank provide the eagles with good viewing areas from which to locate food. At night, the eagles move to the more sheltered inland areas, usually conifer stands, that offer protection from the wind and cold temperatures. The Audubon Society records eagle sightings in New Hampshire and has found that the level of winter eagle activity on the Merrimack River is second only to that on the Great Bay. As one of New England's major north-south running rivers, the Lower Merrimack River also serves as an important migratory route for waterfowl and songbirds.

The New Hampshire Natural Heritage Inventory has identified one state endangered plant species, the Wild Lupine, and seven state threatened plant species within the river corridor. In addition, the river corridor supports three exemplary natural communities: the Southern New England lake sediment/river terrace forest, New England pitch pine/scrub oak barren, and the Northern New England level bog. One state threatened reptile, the eastern hognose snake, is also believed to live in the river corridor.

b. Fishery Resources: Anadromous fish species - fish that live in saltwater and return to freshwater to spawn - are beginning to return to the Lower Merrimack River as the result of a cooperative state-federal restoration program that began in 1969. The completion of a fish passage facility at the Pawtucket Dam in 1986 has allowed american shad to move upstream to Manchester after more than a century's absence. New and improved fish passage facilities and on-going research efforts are directed toward the return of the native Atlantic salmon as far north as the waters of the Pemigewasset River.

The New Hampshire Natural Heritage Inventory lists the state endangered banded sunfish as occurring in the Lower Merrimack River. The Department of Fish and Game stocks the river with rainbow and brook trout.

c. Scenic Values: The Lower Merrimack River offers beautiful views of one of New Hampshire's largest "working" rivers. From the river itself, the banks are forested and rise to a level sufficient to screen from view much of the development within the corridor. Panoramic views of the river and its corridor are possible from bridge crossings and other public access points.

2. Managed Resources

a. Water Withdrawals: The Lower Merrimack River is an important surface water supply for both domestic and commercial purposes in the four river communities and the region. Five large water users have registered with the Water Resources Division of the Department of Environmental Services, including Pennichuck Water Works, a golf club, and three agricultural operations. Population growth in southern New Hampshire is expected to increase demand for water withdrawals from the Lower Merrimack River.

b. Wastewater Discharges: As an assimilator of municipal and industrial wastewater, the Lower Merrimack River serves a vital function. Ten permits to discharge wastewater to the river have been granted under the federal Clean Water Act and state water quality laws. Dischargers include three municipal wastewater treatment facilities, five industrial facilities, a shopping mall, and a fish hatchery. Again, population growth and development in this region of the state will likely lead to additional applications to discharge wastewater to the river.

3. Cultural Resources

a. Historic/Archaeological Resources: The Merrimack River played a pivotal role in the settlement and subsequent development of the region. The river and its banks provided many resources for early inhabitants, including fish, migratory birds, and an important route for communication and transportation. Prehistoric and historic sites along the river include Indian sites, cellar holes, cemeteries and the remains of a canal navigation system. Two archaeological sites in the town of Litchfield have been deemed eligible for listing on the National Register of Historic Places: the Thebodeau site north of Chase Brook and the Danforth Archaeological District in south Litchfield. The American Canal Society believes that the lock at Cromwells Falls is the best remaining specimen of the Merrimack River Navigation System and should be stabilized and preserved.

b. Community Resources: The Lower Merrimack River provides many significant resources for the four river communities, including recreation, water supply, waste assimilation, and open space. The importance of the river has been formally recognized in the each community's master plan and recommendations for additional river protection through the use of zoning, subdivision and site plan review regulations. Recently, the Nashua Regional Planning Commission, with the assistance and cooperation of representatives from each of the four river communities, prepared a river corridor management plan for the Lower Merrimack River. The plan is designed to assist the communities in guiding and managing growth along the river.

4. Recreational Resources

a. Boating: Current boating activities on the Lower Merrimack River include canoeing, kayaking, crewing, and power boating. Although a lack of public access has limited boating activities, the river has enormous potential to meet the increasing recreational needs of the growing region. The river provides both quickwater and flatwater experiences for canoeists and kayakers and is one of the only large surface water bodies in the region.

b. Fishing: Small and large mouth bass are important game species sought by anglers on the Lower Merrimack River. The restoration of anadromous salmon and additional public access sites will increase the use of the river for fishing.

c. Other Recreation Potential: The Lower Merrimack River has tremendous potential to support a variety of recreational activities, both on the water and on shore. Efforts are underway to obtain easements for a hiking trail that would become part of the New Hampshire Heritage Trail, stretching from the Massachusetts border, up the Merrimack, Pemigewasset, and Connecticut Rivers to the Canadian border. Improved access and water quality will lead to the increased use of the river for swimming and fishing.

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