Dam removal restores flow and habitat
Wed, Sep 07, 2011 at 01:45 PM
By The Nature Conservancy
A team from The Nature Conservancy and the Connecticut Department of Energy and Environmental Protection recently completed the removal of two degraded dams on the Aspetuck River in Westport, Conn. The work will help restore habitat diversity and stream connectivity, which offer potential long-term benefits to numerous species, including native brook trout and migratory alewife and blueback herring.
Because the work in Westport was done at relatively low cost, with full support of the private property owner and without heavy equipment, it highlights the potential for dam removal in a state with more than 4,000 dams, most of which are privately owned.
“In many of Connecticut’s rivers, the dams are quite small. Most no longer serve the purpose for which they were built, and there may be a cost to maintaining them,” said Sally Harold, the Conservancy’s director of Connecticut River initiatives and diadromous fish — those that depend on access to both fresh water and salt water to complete their life cycles. “With more than 5,000 miles of stream in the state, there’s a lot we can do to protect and restore the rich diversity of aquatic habitats that support our native species.”
Removal of the dams in Westport will help restore riffle habitat. Riffles are shallow areas with swift moving water that support many stream organisms. As the water churns through shallow areas, it picks up oxygen. In the heavily dammed Aspetuck River, this type of habitat, which can support brook trout and an array of insects and other creatures, is in short supply.
The dams’ removal will improve connectivity, which lets fish and other aquatic creatures travel more freely and gives fish, such as alewife and blueback herring, access to upstream habitats that may be critical for spawning.
Restoring stream flow also enhances water quality by improving nutrient and sediment transport. In addition, migratory fish carry juvenile mussels that are important water filters. When migratory fish can reach more miles of stream, those streams will benefit from the mussels that drop off their gills.
Dam removal also benefits people by improving recreational fishing opportunities and, in some cases, minimizing the risks of flood damage. Dam removal can also enhance local wildlife populations, providing opportunities for people that love to see these birds and other animals. Even in the most urban setting, fish-eating birds will quickly return to a river when fish passage is restored.
MNN is working with The Nature Conservancy to bring you state-by-state environmental information.
Photo of Tingue Dam on the Naugatuck River in Seymour, Conn.: NPCA/Flickr
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