The Piscataquog River in southern New Hampshire is one of the major tributaries of the Merrimack River and prime habitat for Atlantic salmon parr. The Piscataquog Watershed Association (PWA) became concerned with stream bank erosion above the Gregg Mill Bridge on Route 13. The erosion had reached a point where it threatened a line of trees along the road. Further erosion could have affected the road and rare aquatic species in the river. The association teamed up with Trout Unlimited and other organizations to explore a relatively new approach to bank stabilization that could be used as a model for the state. The association received a grant from the New Hampshire Department of Environmental Services to protect the bank and stream habitat using “natural” techniques that redirect flow away from the bank.
The project involved several steps including: Installing two log veins projecting from the bank into the river. Two root wads to protect the bank and veins. An ice bumper to protect existing trees from further ice damage. A porous rock weir placed upstream of the veins. The veins and weir are designed to redirect from to the center of the river. As part of the project runoff from Route 13 was redirected away from the river.
St Anselm College was a co-sponsor of the project and provided design assistance and supervision of activities affecting stream habitat. Trout Unlimited River Restoration Specialist Jim MacCartney provided technical assistance and supervision of the installation. Trout Unlimited Merrimack River Valley Chapter volunteer’s provided all of the labor. Also assisting on the project were the Town of New Boston, NH Department of Environmental Services, NH Department of Transportation and the Natural Recourses Conservation Service.
In early August volunteers took to the water setting up screens and booms to protect down stream habitat. Working in ninety-degree temperature PWA president Margaret Watkins joined the volunteers filling and carrying sandbags to hold the screening in place in the river. The majority of the work was completed in two weeks and it wasn’t long before the new home to be occupied. What used to be riffles about ankle deep was converted into a four feet pool.
As part of the analysis for the project a section of the river was electroshocked. There were still brook trout in the river during one of the warmest summers on record. One of the workers on the project grew up in New Boston and talked about what the river was like back in the 50’s. There were spring holes that used to hold trout all summer. Development and erosion have taken it’s toll on the river but the Gregg Mills Bridge project can’t help but make people wonder what the river would be like if a restoration project could be completed every few years.
The Piscataquog is one of several Trout Unlimited restoration projects underway in New Hampshire.
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Setting up the silt screen
Setting rocks under the roots of an oak tree
The finished project