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Winnicut River Dam Removal, Monitoring Plan
New Hampshire Department of Environmental Services and New Hampshire Fish and Game Department
Contributing Institution
UC Riverside, Library, Water Resources Collections and Archives
Clearinghouse for Dam Removal Information (CDRI)
Rights Information
Transmission or reproduction of materials protected by copyright beyond that allowed by fair use requires the written permission of the copyright owners. Works not in the public domain cannot be commercially exploited without permission of the copyright owner. Responsibility for any use rests exclusively with the user.
Scope/Content: Abstract: The Winnicut River originates in the low-lying hills of New Hampshire's coastal plain, flowing north into Great Bay Estuary. Although a relatively small watershed (17.5 mi2), the Winnicut River is an ecologically significant tributary to the Great Bay. In 1957, a low head dam with an adjoining Canadian step-weir fish ladder was constructed in the footprint of a legacy dam, with the intention of benefitting waterfowl and aiding in fish passage. The Winnicut River Dam was located in the tidal portion of the river near the confluence with Great Bay. The dam and its associated fish ladder were owned, operated, and maintained by the NH Fish and Game Department. The 1957 fish ladder required significant annual maintenance and did not allow herring and other fish to migrate effectively throughout the river system. The Winnicut River provides spawning and rearing habitat for several significant anadromous coastal fish species including Osmerus mordax (rainbow smelt), Alosa spp. (river herring), and Anguilla rostrata (American eel). Once restored, the Winnicut River will be the only coastal river in N.H. with adequate upstream and downstream passage for migrating fish. A feasibility study completed in 2006 revealed that the Route 33 crossing over the Winnicut River (immediately upstream of the dam) severely narrowed the channel cross section. The study indicated that a velocity fish passage barrier would be created beneath Rt. 33 if the dam were removed. The NHFGD decided to remove the Winnicut River Dam and adjoining Canadian step-weir fish ladder and construct a 132 ft long x 20 ft wide pooland-weir, run-of river, cast-in-place concrete fishpass beneath the Route-33 Bridge. The new fish pass will maintain the water levation within the impoundment upstream of Route 33; however, at approximately 18 inches below conditions that existed with the dam in place. Implementation of the Winnicut River Restoration Project will result in several appreciable changes to the Winnicut ecosystem. These include re-opening 39 miles of riverine habitat within the Winnicut River Watershed, restoring some of the 5,500 ft of riverine habitat disturbed from the creation of the impoundment, and restoring 21,000 square feet of intertidal habitat.
Scope/Content: Date constructed: 1957. Date removed: 2010.
Ecology and river restoration
Fisheries and fish passage
Pre- and post-project monitoring
Dam retirement
Winnicut River, NH
Winnicut Dam

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