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New Hampshire Department of Environmental Services
PUBLIC GOVERNMENT BUSINESS A to Z LIST

Designated Rivers
Isinglass River

II. The Isinglass River Nomination

A. Description

The Isinglass River begins at outlet of Bow Lake in the Town of Strafford and flows approximately 18 miles through the Town of Barrington and a portion of the City of Rochester before reaching its confluence with the Cocheco River. The Isinglass River watershed drains an area of approximately 75 square miles. From its headwaters at Bow Lake to its confluence with the Cocheco River, the Isinglass River flows through a diverse landscape comprised of wetland complexes, rocky outcroppings, and a mix of conifer and deciduous New England forests.

Land use along the Isinglass River is primarily rural. Given the river's proximity to the rapidly developing seacoast region, it is important to recognize that the river corridor remains largely undeveloped, with only periodic bridge crossings and occasional riverside residential development. Also noteworthy, is the free flowing nature of the river, as it is uninterrupted by dams for its entire length. From its headwaters, the ecosystems within Isinglass River corridor are best characterized as dry coastal forest with pockets of wet and moist coastal forests intermixed near the wetland complexes. Presumably, the river exists today, largely as it did over three hundred years ago prior to European colonization.

B. River Values and Characteristics

The RMPP identifies a number of river-related values and characteristics that qualify a river for designation. The Isinglass River supports many of these including a variety of natural, managed, cultural, recreational, and other resource values. Some are significant at the local level; others are significant at the state or national level. The resource values which qualify the Isinglass River for designation include geology, wildlife, vegetation and natural communities, fish, water quality, natural flow, open space, water withdrawal, historic and archeological, community river resources, boating, other recreation, public access, scenery, land use, land use controls, and water quantity.

1. Natural Resources

a. Geologic Resources: Similar to most of New Hampshire, the bedrock underlying the Isinglass River corridor was covered by unconsolidated deposits of till following the last glaciation. A valuable mineral known as mica was mined from the Town of Strafford during the early 1900s. This mineral, also referred to as "Isinglass", was used to make windows, lampshades, clock faces, and other goods and accounts for the river's name. In areas where the underlying bedrock protrudes, unique rock formations are visible and account for the scenic cascades and waterfalls over which the river flows. A study of the river corridor's surface geology concluded that the contemporary Isinglass riverbed is a remnant of a much larger river channel, known as the Mallego Channel, that was anywhere from 40 to 70 feet deep. While the groundwater resources in the area include several aquifers within the Isinglass corridor, none of these are reported to be significant.

b. Wildlife Resources: The Isinglass River corridor supports a diversity of habitats comprised of wetlands, forests, and open space that is home to a wide variety of wildlife. Especially important are the large tracks (>500 acres) of unfragmented land that extend northward from the river corridor. Similarly, the wetland complexes scattered throughout the river corridor, such as those where Nippo Brook and the Mohawk River drain into the Isinglass, serve as important wildlife refuges and travel routes. A total of six wildlife species, listed as threatened or endangered at either the state or national level, have been reported from the Isinglass River corridor. These include the bald eagle, common loon, osprey, Cooper's hawk, common nighthawk, and the small-footed bat. According to the New Hampshire Fish and Game Department, the wildlife habitat in the river corridor is rated as moderately to very diverse depending on the potential for human encroachment.

c. Vegetation and Natural Communities: The vegetation occurring within the Isinglass River corridor is consistent with that found in the coastal drainage of New Hampshire and reflects a diversity of upland, lowland, and wetland plant species. New Hampshire's Natural Heritage Inventory (NHI) reports 11 plant species from the municipalities that the Isinglass flows through that are rare, of special concern, or threatened at the state level. They are huckleberry, large yellow lady's slipper, pitcher plant, ginseng, trailing arbutus, American plum, wild lupine, slender crab-grass, river bank quillwort, Englemann's quillwort, and climbing hempweed. Black gum/red maple and northern New England rich mesic forest types have also been identified as "exemplary natural communities", as defined by NHI, that occur within the Isinglass corridor. It is important to note, that much of the riparian zone immediately adjacent to the river is largely forested and acts as an important buffer providing shade and filtering out potential pollutants.

d. Fish Resources: The Isinglass River is best characterized as coldwater fishery that provides habitat for approximately 20 resident warm and coldwater fish species. Naturally occurring game species include the small and largemouth bass. Naturally occurring nongame fishes include common species such as bluegill, common shiner, fall fish, brown bullhead, and the common sucker. An uncommon nongame species, known as the blacknose shiner, is found in the Isinglass River and has very limited distribution in New Hampshire. Introduced game species include brook, brown, and rainbow trout. The river is stocked annually with these trout species as well as Atlantic salmon as part of an ongoing anadromous fish restoration effort, unique to the Lamprey and Cocheco drainages in the coastal basin. Much of this stocking occurs in the Town of Barrington between routes 126 and 202.

The New Hampshire Fish and Game Department reports a diverse range of fish habitats in the Isinglass River. The free flowing nature, an extensive riparian buffer, high water quality (see below), and varied substrate types of the Isinglass River are the primary factors that account for the diverse habitats within the river.

e. Water Quality: The Isinglass River has been designated a Class B water by the General Court. The Department of Environmental Services periodically monitors (1990, 1998) the water quality of the Isinglass River at two locations, the route 202 bridge in Barrington and Rochester Neck Road bridge in Rochester. In addition the IRPP conducted volunteer monitoring on the Isinglass River during summer 2000. Based on sampling results from 1990, 1998, and 2000 the river is currently fully supporting the standards of this water quality goal. The significance of maintaining a high level of water quality in the Isinglass River is evidenced by the use of the river for recreational purposes, by the presence of a cold water fishery, its use as a public water supply for the City of Dover, and as a significant contributing factor to the water quality observed in the Cocheco River downstream of its confluence with the Isinglass.

f. Natural Flow Characteristics: From its headwaters at the Bow Lake dam in the Town of Strafford, the Isinglass River is 100% percent free-flowing. There are no gaging stations on the Isinglass, however, median flows have been estimated from nearby gaging stations and range from a high in April of 222 cubic feet per second (cfs) to a low of 12 cfs in September. The Isinglass watershed is approximately 75 square miles. The major tributaries of the Isinglass River include the Mohawk River, Nippo Brook, Berry's River, Green Hill Brook, and the outlets of Hanson and Ayers Ponds.

g. Open Space: The Isinglass River corridor is predominantly undeveloped. From its inception at the Bow Lake Dam, the river flows through a short section of low impact development in Center Strafford before crossing under route 202A. From this point to the route 126 crossing in the Town of Barrington (approximately 6 miles) the river flows through a large tract of undeveloped land consisting of forested uplands and wetlands. Only one distant residential development is contained within the river corridor in this section of river. Access to the river through this stretch is limited to a closed Class VI road, known as Pig Lane, which provides access to a 17-acre conservation area leased by the Town of Strafford from the New Hampshire Water Resources Council.

Below the route 126 bridge to the route 202 bridge, the river is visible from route 202 and provides excellent access for anglers and paddlers. Though some development is present, the river is best characterized as rural, with minimal impact caused by roadways and scattered residential housing. Below the route 202 bridge, the nearest roadway to the river is Scruton Pond Road. From here to the Green Hill Road bridge high banks covered with a mix of deciduous and coniferous forests and a few seasonally wet floodplain areas buffer the river. Through this section of the river corridor much of the land abutting the river is privately owned and remains undeveloped.

A majority of the development within the Isinglass corridor occurs from the Green Hill Road bridge to the river's confluence with the Cocheco River. This development, however, is limited to small cluster housing developments and bridge crossings. In fact, one of the largest pieces of land dedicated to open space in the Isinglass corridor occurs within the City of Rochester and is owned by Waste Management, Inc. Known as the Turnkey Landfill facility, Waste Management, Inc. has dedicated over 100 acres of riverfront property from this operation to open space. Although no permanent development restrictions are placed on it, this parcel of land has a network of forested streamside trails, a picnic area, and a canoe launch.

2. Managed Resources

a. Impoundments: There are no impoundments on the Isinglass River proper. Six breached dam sites have been identified from a database maintained by the Department of Environmental Services. Several other dams exist on tributaries to the Isinglass River.

b. Water Withdrawals and Discharges: The City of Dover maintains the only registered water withdrawal (>20,000 gallons per day) on the Isinglass River. Dover withdraws an average of 830,000 gallons of water per day from the Isinglass River from a point just downstream of the Rochester Neck Road bridge in the City of Rochester. The water is pumped to a recharge well and serves as public water supply. One additional withdrawal point is known from within the watershed, on the Berry's River, a tributary to the Isinglass River. Water is diverted from the Berry's River to the City of Rochester's water supply reservoir. However, because the city only reports the total amount of treated water they produce it is not possible to know how much of that water comes from the Berry's River (see III. Considerations for Protection of Instream Flow below).

Currently no permitted point source discharges exist on the Isinglass River.

c. Hydroelectric Resources: There are no existing hydroelectric power production facilities on the Isinglass River. Although potential hydroelectric power sites have been identified on the Isinglass River, none have been pursued, and therefore do not appear to be of great potential.

3. Cultural Resources

a. Historic and Archaeological Resources: Similar to many of the waterways of New Hampshire, there is ample evidence of pre-European settlement in the Isinglass River corridor. Both artifacts and written histories of riverside trails suggest that native inhabitants of this region utilized the Isinglass River as a food and water source, as well as a travel way. Colonization of this region by European settlers led to more intense use of the resources contained within the river corridor, including wood harvesting for ship masts and subsequently utilization of the river to transport the materials downstream to a more accessible seaport. At least nine historic mill sites are known to exist on the Isinglass River. These were used to produce a variety of goods ranging from flower to lumber. The remnants of these mill sites are still visible at many locations along the river, with perhaps the most impressive being the Locke Mill site in the City of Rochester. Other notable historic resources contained within the riverfront communities include the Ayers Lake Campground, eligible for historic listing at the state level and the Squanamagonic Community, an example of pre-European development and a potential historic district.

b. Community River Resources: The importance of the Isinglass River as a community resource is reflected in the local planning and protection efforts of the communities along the River. The river is recognized extensively by the Town of Barrington and has been included in its Regional Environmental Planning Report and the town's Master Plan. The communities of Strafford and Rochester have also recognized the importance of the river as a community resource through the lease or purchase of riverfront lands that ensure public access and protect the undeveloped nature of riparian lands.

4. Recreational Resources

a. Fishery: The Isinglass River is stocked annually with approximately 6,000 brook, brown and rainbow trout and managed by the New Hampshire Fish and Game Department as a "put-and-take" coldwater fishery. There are additional angling opportunities for warmwater fish, including species such and bass and brown bullhead. The Isinglass is considered an important seacoast trout stream by local anglers and is heavily utilized as such during May and June. Most of the fishing is done along routes 126 and 202 in the Town of Barrington.

b. Boating: The free-flowing nature of the Isinglass River provides both challenging whitewater and relaxing flatwater boating opportunities for canoeists and kayakers. The rapids beginning along route 126 are best run in the spring at medium to high water. Various published river guides rate the river as Class II. Less challenging stretches of the river provide paddlers with opportunities for wildlife and scenic viewing.

c. Other Recreation: Swimming, hiking, and birdwatching are other recreational activities that people enjoy in or near to the Isinglass River. The multipurpose recreational facility owned by Waste Management, Inc. provides opportunities for hiking, swimming, and picnicking. Recent efforts by the Town of Barrington also include the initiation of a riverside trail. The Pig Lane Road access is a popular walking trail and affords excellent opportunities to see upland wildlife species such a deer and owls.

d. Public Access: There are a variety of public and private access points to the Isinglass River, some publicly owned and some private. Publicly owned access points lack dedicated parking, but exist at most of the major bridge crossings (routes 126, 202A, 202, and 125). The section of river that runs near routes 126 and 202 has gravel parking areas where the river can be accessed for fishing or paddling. The Pig Lane Road access point provides an opportunity to view the remnants of the Foss Mill. Waste Management, Inc.'s recreational facility is the only formal access point along the river open to the public. A number lesser known privately held access points exist along the river.

5. Other Resources

a. Scenery: Scenic opportunities abound in the Isinglass River corridor. Immediately upstream of the route 202 bridge crossing the remains of Twombley's Grist Mill can be seen as well as the narrow sluice that the river flows through. The Locke Mill site provides, perhaps, the most spectacular view along the river. At this location, visitors are able to observe a 25-foot waterfall and in the springtime, when water levels are high, get a sense for the power of the river.

b. Land Use: Land use within the river corridor is almost exclusively residential. Two residential developments are situated along the Isinglass: one just below route 202A in the Town of Strafford and a second off Flagg Road in the City of Rochester. The remaining residential development is scattered throughout the river corridor. Industrial and commercial land use within the corridor is limited to a motel, a construction equipment rental company, an auto body business, and inactive gravel pit. Waste Management, Inc.'s landfill facility in Rochester represents, by far, the largest industrial activity within the corridor. However, it is setback from the river and has an extensive forested riparian corridor between the landfill and the river. The undeveloped nature of the river corridor and its nearness to the rapidly developing seacoast region make the protection of Isinglass River a priority.

c. Land Use Controls: The Town of Strafford has enacted a 50-foot setback for all primary structures and a 100-foot setback for septic systems. In addition, Federal Emergency Management Agency regulations apply to all lands designated as special flood hazard zones as defined in the flood insurance study completed for the town. In the Town of Barrington, a 100-foot setback applies to all primary structures built along the Isinglass. Special minimum lot size building regulations also limit the amount of wetland that can be contained within a specific building lot. It is also important to note that the requirements of the Comprehensive Shoreland Protection Act (RSA 483-B) apply to the point where Nippo Brook enters the Isinglass River in Barrington to its confluence with the Cocheco River. The City of Rochester has few river corridor specific land use controls, but has enacted a specific ordinance establishing setbacks for solid waste facilities.

d. Water Quantity: There are no gage stations on the Isinglass River. Flow estimates, extrapolated from nearby gages indicate that maximum median monthly flow occurs in April (222 cfs) and minimum median monthly flows occur in September (12 cfs).

e. Riparian Interests/Flowage Rights: The only known dam flowage rights on the river belong to the New Hampshire Water Resources Board and were granted by the Public Service of New Hampshire in 1962 at all the historic mill sites on the river. These rights do not detail any specific flooding elevation, rather "all rights of the grantor are transferred to the grantee".




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