Nashua River Watershed Statistics

Total Drainage Area: 538 square miles
Massachusetts Drainage Area: 454 square miles
New Hampshire Drainage Area: 74 square miles
Total Length of Nashua River: 56 miles
Massachusetts Total Length of Nashua River: 46 miles
New Hampshire Total Length of Nashua River: 10 miles
Major Tributaries: Nissitissit, North Nashua, Quinapoxet, South Nashua, Squannacook, and Stillwater Rivers
Total Forest Area: 62.6%
Total Residential Area: 13.3%
Total Agricultural Area: 11.9%
Approximate Surface Area of Lakes, Ponds and Reservoirs: 6,818 acres

Factoids

The main stem of the Nashua River flows north from Lancaster, MA (the confluence of the North Nashua River and the South Nashua River) to Nashua, NH where it joins with the Merrimack River to flow to the Atlantic Ocean.

An award-winning children’s story was written about the clean-up of the Nashua River, A River Ran Wild, by Lynne Cherry.

The name Nashua comes from the native word for the river “Nash-a-way” meaning “river with the pebbled bottom.”

Our Flora and Fauna

The Nashua River watershed is made up of forests, streams, fields, wetlands, ponds, and other ecosystems that provide the perfect habitat for an abundance of plants and animals. Our watershed also contains less common habitat including old growth forest and peat bogs. The river channels, back cove areas, tributaries, and the riparian land along the river edge serve as host to thousands of plant and animal species. Below is an overview of flora and fauna in and along our rivers and streams.

The Nashua River and Its Tributaries

Flora:

Along the river and its tributaries, there is a healthy diversity of riparian trees, shrubs and herbaceous plants. Many of the tree species found along the river can also be found in lowland forest throughout central Massachusetts. The towering white pine (Pinus strobus) is a tall pine tree often found growing with red maple (Acer Rubrum). In some locations, the swamp white oak (Quercus bicolor) with its round-tipped leaves might be found. Black willow (Salix nigra) with small gray-green leaves and sycamore (Platanus occidentalis), with gray-brown mottled bark are typical river tree species. Yellow and white birch can be seen in sunny areas, and both with bark covered with large lenticels. Alnus serrulata or common alder is a shrub with birch-like catkins which bloom in mid-to late March. Vines such as poison ivy and wild grape can be seen on the shoreline in some locations.

In the river, one can find a variety of emergent plant-life like pickerel weed (Pontederia cordata L.), cattails (Typha latiflia) and many different sedges and rushes. Floating on the surface of the river, in calm areas, wolfia (Wolffia columbiana Karst) and duck weed (Lemns minor) can be seen. A curious person looking under the water will find common hornwort (Ceratophyllum demersum), a bushy plant often described as similar to a raccoon tail. A local carnivorous plant called common bladderwort (U. vulgaris)can be found thriving in the back coves and corners.

Go Botany created by the New England Wild Flower Society.

Fauna:

Birds

Baltimore orioles, red wing blackbirds, tree and barn swallows, belted kingfishers, and a variety of warblers join mallards, Canada geese, and other waterfowl as seasonal visitors or local residents of the Nashua River and its tributaries. Great blue herons, our largest birds standing four feet high, can be spotted hunting fish and frogs in the back coves and along the shallow edges. Birds of prey including red-tailed hawks, osprey, and bald eagles are frequently spotted along our rivers also.

Insects and Spiders

Rivers provide perfect habitat for the aquatic stages of many insects, and their presence helps us determine the health of our river. Water striders walk across the water with long legs and are easy to see. Whirligig beetles (Gyrinidae) are small black beetles that spin on the surface of the water, sometimes in large groups. Damselflies and dragonflies (Odonata) of many different species, are found resting on vegetation, flying above the water surface, or laying their eggs in the river. Their nymphs can be found lurking in the detritus or leaf litter at the bottom of the river. Stilt spiders (tetragnatha sps.) are one of many species that build their webs on river vegetation, and crayfish (Astacoidea) may be seen hunting along the river bottom or hiding in the rocky corners.

Mammals
Beaver (Castor canadensis), river otter (Lontra canadensis), muskrat (Ondatra zibethicus), and mink (Neovison vison) are our most common mammals living along the banks of the Nashua and its tributaries. Beaver are large (35-60 pounds) and will smack their tail on the surface of the water to sound an alarm. Lodges, dams, and scent mounds, the structural signs of these amazing animals, are scattered throughout the waterways. Also, trees chewed by beaver are easy to spot with clear teeth marks on the trunks. River otter may be seen swimming or their “slides” may be located on the muddy banks. Muskrat build mounds made of cattail, which can often be seen in wetlands, and they leave their “scat” on floating logs.

Reptiles
Painted turtles and musk turtles, commonly found in the river, can be seen basking on logs along the river edges. Our largest resident, the snapping turtle, may be seen swimming, resting below surface in the shallow areas or basking on the muddy banks. The northern water snake, capable of reaching three feet in length, is a harmless but quick-tempered resident often spotted swimming in the river or warming in low branches along the river banks.

Fish
Sections of the Nashua River are renowned for large mouth bass and draw numerous fishermen to its waters. Sunfish, pickerels, and yellow perch set up residence in the back coves and trout can be found in the upper tributaries where the water stays cooler and more oxygenated. Bullhead catfish scour the river bottoms and minnows are seen schooling in the weed beds.

Be sure to visit our Nature Photo Gallery. And we’d love to have you share your stories of plants and animals you’ve seen, and be sure to include a photo if you have one.  You can email your stories and photos to This email address is being protected from spambots. You need JavaScript enabled to view it.. 

Geology of Our Watershed

The bedrock underpinning of the Nashua River watershed is made up of two types of rock: granite and some other igneous types of rock, and metamorphic rock, primarily schist and gneiss.

Over ten thousand years ago, during the Pleistocene Epoch, the Nashua River valley was carved by moving glacial ice that was over one mile deep. The Nashua River itself was once Glacial Lake Nashua, an enormous lake that extended from Boylston, Massachusetts north to Nashua, New Hampshire. At this time, it flowed southward through the Worcester area.

Bedrock and a thin layer of glacial till “hardpan” dominate the higher elevations of the watershed, especially to the west and northwest, where the main tributaries to the river rise (Quinapoxet, Stillwater, North Nashua, Squannacook, and Nissitissit Rivers). These rivers all flow from the northwest to the southeast. The rivers meet the Nashua River at sharp angles, turning to join the Nashua River to flow in a northeasterly direction (except where the Quinapoxet and Stillwater Rivers enter the artificially created Wachusett Reservoir). The flow of the tributaries is a piece of the evidence that the Nashua River used to flow south. The river’s course was reversed as the edge of the last ice age glacier melted away, leaving Glacial Lake Nashua to drain to the north.

The central part of the watershed is dominated by sand and gravel deposits created by the valley’s history of glaciations. These deposits are the groundwater source for many of the watershed’s municipal water supplies.

To view U.S. Geologic Survey images of Glacial Lake Nashua features taken in 1906, click here, then enter Glacial Lake Nashua in the search box at the upper right of the page.

For a fascinating hike, take a walk at the Oak Hill Conservation Area in Harvard and Littleton, MA. There you can see Tophet Chasm, an ancient outflow of Glacial Lake Nashua. Lake water rushing out through a weak fault area in the hill, created a 120 foot waterfall and carved this deep chasm. The chasm is now dry, but still impressive. The area is the property of the Littleton Conservation Trust.

Our Rivers and Streams

Rivers and streams have been important to human existence from the beginning of time, first as a source of drinking water and food, and later becoming a means of transportation. The rivers and streams of our watershed are no different. The native people, and later colonists, were able to sustain their communities with the abundant supply of water, food, and shelter materials in our region. Rivers became pathways into interior lands, where new communities were settled, and the rivers were used for transporting goods to and from those towns. As the industrial age began, the power of the rivers was harnessed to provide energy to mills of all types. Today, the rivers flowing through our cities are a catalyst of economic revitalization, while the rivers flowing through our smaller communities provide numerous recreational opportunities. The rivers also serve as an indicator of the environmental health of the entire region’s ecosystem, because what we do on the land is reflected in the quality and quantity of our water.

So what rivers and streams flow through the Nashua River watershed? To answer that, first we need to know “What is a watershed?”  In the case of the Nashua River, the watershed includes all of the land draining water to the Nashua River, which meets the Merrimack River in Nashua, New Hampshire.

The Nashua River watershed can be divided into four major aggregate subwatersheds: North Nashua River, Wachusett Reservoir, Nashua River mainstem, and the Squannacook and Nissitissit Rivers watersheds.

North Nashua River (Massachusetts only)
The North Nashua begins at the confluence of the Whitman River and Flag Brook in west Fitchburg. Nine dams and flood control retaining walls dominate the North Nashua as it passes through the City of Fitchburg. The river receives discharges from both the East Fitchburg and Leominster Wastewater Treatment Plants, and stormwater runoff from the cities of Leominster and Fitchburg. The river flows through Leominster State Forest and agricultural fields before joining with the South Nashua River in Lancaster.

North Nashua River tributaries include: Fall Brook, Falulah/Baker Brook, Flag Brook, Monoosnoc Brook, Phillips Brook, Wekepeke Brook, and Whitman River.

Wachusett Reservoir Sub-basin (Massachusetts only)
Wachusett Reservoir and its tributaries in the southwestern portion of the Nashua River watershed are water supply sources for the Massachusetts Water Resources Authority (MWRA), the public water system in eastern Massachusetts that supplies drinking water to Boston and the metropolitan area. The reservoir is created by the Wachusett Dam in Clinton which was built in 1897. The Quinapoxet and Stillwater Rivers, both high quality water sources that flow into the reservoir, are popular cold water fisheries. The water exiting the dam forms the South Nashua River flowing north to meet the North Nashua River in Lancaster. The Clinton Wastewater Treatment Plant operated by the MWRA is located on the South Nashua River.

Wachusett Reservoir tributaries include: Ball Brook, Chaffins Brook, Connelly Brook, East Wachusett Brook, French Brook, Gates Brook, Houghton Brook, Justice Brook, Keyes Brook, Quinapoxet River, Rocky Brook, and Stillwater River.

Nashua River Mainstem Sub-basin (Massachusetts and New Hampshire)
The Nashua River mainstem forms the core of the Bolton Flats Wildlife Management Area and the Oxbow National Wildlife Refuge in Lancaster, Bolton, and Harvard where it winds north through marshy areas and former agricultural fields. Pepperell Dam in east Pepperell forms Pepperell Pond, an impoundment on the river popular for trophy large mouth bass and duck hunting. The river flows north through Hollis and Nashua, Hampshire where it joins the Merrimack River. The towns of Ayer and Pepperell have wastewater treatment plants discharging directly to the mainstem Nashua River. The Devens Wastewater Treatment Plant has a subsurface wastewater discharge.

Nashua River Mainstem tributaries include: Bowers Brook, Catacunemaug Brook, Flints Brook, James Brook, Mulpus Brook, Nonacoicus Brook, North Nashua River, South Nashua River, Still River, Unkety Brook, and Varnum Brook. 

Squannacook and Nissitissit Rivers Sub-basin (Massachusetts and New Hampshire)
The Squannacook and Nissitissit Rivers both flow directly into the Nashua River Mainstem. The Squannacook River flows through Townsend and Shirley. Hollingsworth and Vose Company, a paper manufacturer, holds the only surface water discharge permit to the Squannacook River. The Nissitissit River flows south from Brookline, New Hampshire through Pepperell. Much of the land along both of these rivers is forested, and protected parcels include the Townsend State Forest, Squannacook Wildlife Management Area, Nissitissit River State Wildlife Management Area. Both rivers are popular cold-water fisheries.

Squannacook River tributaries include: Lock Brook, Mason Brook, Pearl Hill Brook, Trap Falls Brook, Walker Brook, Willard Brook, and Witches Brook.
Nissitissit River tributaries include: Beaver Brook, Gulf Brook, Lancey Brook, and Sucker Brook.

More on the water quality of our rivers and streams. 

More on recreation in our watershed.