Nash Stream, NH

Background

Nash Stream was once renowned as a high quality native brook trout stream that provided exceptional angling opportunities. It is also former Atlantic salmon habitat. The river and its tributaries still contain native brook trout, but not in the numbers once seen due to historic log drives and a catastrophic dam breach.

Nash Stream is located in northern New Hampshire. More than 90% of the Nash Stream watershed lies within the publicly-owned Nash Stream State Forest. The watershed comprises 28,332 acres (44.3 square miles) within the towns of Stratford, Odell and Stark in the upper Connecticut River basin. The mainstem is about fourteen miles long from its headwaters to the confluence with the Upper Ammonoosuc River. There are nine named perennial tributaries, as well as several unnamed tributaries with perennial flow.

History

The watershed has been a working forest since the mid 1800s. A railroad for logging was built in 1852. In 1870, the Nash Stream Improvement Company was incorporated for the purpose of clearing the stream of boulders and snags and building a series of dams for log drives. The largest of these, the Nash Bog Dam, was completed in 1900. The 236-acre impoundment created by the dam stored water for driving the logs. In the 1930s, haul roads were built to carry logs from the forest and the river drives ended. The dam at Nash Bog Pond was maintained to support seasonal camps that were built around the impoundment. Unfortunately, in 1969 the dam failed, sending a torrent of water akin to the 500-year flood event down Nash Stream. Bulldozers and skidders were used to clean up after the flood and reopen the roads for logging and access to the camps. In the process, Nash Stream was straightened and its banks made higher.

Challenges

As a result of the dam breach, much of the instream and riparian habitat was altered to the detriment of wild brook trout and other fish species. This included the loss of over-story canopy which resulted in higher water temperatures, and limited the suitability of mainstem habitat for all life stages of salmonids. Subsequent bulldozing further affected the river corridor and channel morphology by eliminating pools, creating a nearly seven mile long stretch of riffle water with limited habitat and spawning value.

Poorly designed culverts along old logging roads compounded matters by blocking or impeding fish passage to critical tributary habitat. Such tributaries fulfill an essential need within a typical river system in terms of providing cold water, which contribute to healthy stream flows and thermal refuge, and in this case, critical spawning habitat, particularly for trout. Although many of these tributaries were relatively healthy, the inability of the fish to access them exacerbated the decline of the fishery. As a result, Nash Stream no longer supports a robust, wild brook trout fishery.

Goal and Objectives

When the State of New Hampshire acquired the Nash Stream Forest in 1988, a management plan was developed. Among other things, the forest management plan calls for managing toward sustainable fisheries of wild populations of indigenous fish by implementing a program for stream habitat protection and enhancement. In 2006, a multi-year, collaborative restoration effort was launched to do just that.

The Nash Stream Restoration Project seeks to improve conditions in the watershed so that it once again functions as a healthy and self-sustaining coldwater fishery. Trout Unlimited and its state partners – NH Department of Resources and Economic Development Division of Forest and Lands (NHDRED) and the NH Fish and Game Department (NHFGD) – are working to restore aquatic habitat and fish passage in the drainage to support a healthy and self-sustaining population of native, wild brook trout. Ultimately, the project seeks to restore over nine miles of mainstem habitat and access to more than six miles of tributary habitat.

Work-to-Date

Geomorphic 2007 – 2008 – A fluvial geomorphologic assessment was performed to document existing conditions and to develop restoration options for Nash Stream. The assessment included measurements of channel form including gradient, cross-section and longitudinal profile, as well as valley confinement and watershed size.

Habitat 1990 and 2005 – Habitat assessments of the instream and riparian conditions of Nash Stream were conducted in 1990 and 2005. Similar assessments were done for Slide, Long Mountain, East Branch and Columbia Brooks in 1990.  These assessments included direct measurements of the area of each habitat type (riffle, glide, pool, cascade) and water depths, and qualitative assessments of substrate characteristics, bank erosion and riparian vegetation.

Water Quality (temperature and pH, alkalinity and conductivity) – Summer water temperature was monitored at four locations in Nash Stream and all but two perennial tributaries between 2005 and 2008.  Additionally, in 2005 water samples for pH, alkalinity and conductivity analysis were collected in three locations in Nash Steam and several tributaries.

Water quantity – In 2005, flow was measured at two locations in Nash Stream and in the five largest tributaries.

Fish data – Between 2005 and 2008, fish surveys were conducted at 36 sites in Nash Stream, and at 25 sites in 10 tributaries.

Research (PIT and Radio) – Beginning in 2007, research began on the genetic structure of wild brook trout in the Nash Steam Watershed and the effects of natural and manmade (culverts) fish passage impediments. This entailed conducting population sampling in Long Mountain and Johnson Brooks, inserting PIT tags into all captured brook trout >60 mm in total length, and tracking fish movement from August 2007 to the present.

Culvert Removal – In November 2007, an impassable culvert on Farrer Brook with a 2.8-foot drop at the outlet was removed. When the culvert and associated valley fill was removed, the forestry road serviced by the culvert was retired and the road revegetated.

Before	After

Current Projects

Designs that establish or promote stable channel conditions were developed for the reach immediately downstream of the former Nash Bog Pond and its dam. These designs were based on natural stream channel design principles using the results of the fluvial geomorphologic assessment. Most are relatively soft approaches and are all geared to allowing the river to restore itself.

Nash Stream mainstem – From confluence of Silver Brook and Nash Stream downstream approximately ¾-miles to a wooden bridge, work is being done instream to restore Nash Stream to its condition prior to the 1969 dam breach. Well-established approaches employing rock and wood placement, as well as other methods of fluvial geomorphic techniques are being used to implement the restoration work.

Culverts – Impassable culverts are being removed on Johnson and Long Mountain Brooks. The two culverts are being replaced with geomorphically transparent structures that are 100% passable by aquatic organisms. Another culvert on lower Pike Brook is also being removed and the road retired.

Future work

Nash Stream mainstem – From the wooden bridge downstream approximately 3 miles to the confluence of Pond Brook and Nash Stream additional instream work is planned for 2009. Again, restoration activities will involve the strategic placement of rock and wood to restore Nash Stream to pre-flood conditions.

Culverts – Impassable culverts will be removed on upper Pike, upper Farrer, Pond, Horseshoe and Slide Brooks. The five culverts will be replaced with geomorphically transparent structures that are 100% passable by aquatic organisms.

For more information, contact:

Jim MacCartney, River Restoration Specialist
18 Low Avenue
Concord, NH 03301-4902
(603) 226-3436
Email Jim MacCartney [1]