Culverts & Dams

Dealing with Culverts and Dams

To many people, “fish passage” means salmon migrating upstream to their spawning grounds and downstream out to sea. However, there is more to the story. American shad and river herring (both alewife and bluebacks) once came up and down the Farmington by the tens of thousands too, and some still make the attempt. American eels and sea lampreys still make the journey every year also. Even local fish like trout and dace need to travel freely within the river to find good habitat. Many more animals—reptiles, amphibians, and mammals—need free passage along the edges of rivers and streams to in order survive and maintain healthy populations. There are hundreds of barriers in their way, many of which are either old dams or culverts where streams pass under roads.

At FRWA, we work with many partners to remove these barriers so fish can continue to migrate up and down the stream. FRWA is a founding member of the Long Island Sound River Restoration Network (RRN). The RRN is a network of Connecticut and New York based environmental organizations dedicated to the restoration and health of regions' rivers. Currently, there are 8 organizations that make up the RRN:

Funding of the RRN is provided by the Long Island Sound Futures Fund. To learn more about the River Restoration Network, go to https://www.savethesound.org/what-we-do/ecological-restoration/river-restoration-network/

Culverts and Stream Crossing Assessments

All forms of wildlife require routes of passage within their habitat in order to find food and shelter. Aquatic wildlife such as fish, mollusks, crustaceans, and insect nymphs also require the ability to move up and down the length of their stream habitat. However, human transportation needs require building infrastructure that allows us to safely pass over these streams. Structures such as bridges allow us to drive over streams on an elevated platform, and culverts divert streamflow to pass underneath roads.

Stream crossings are places where streams are crossed by roads, railways, or pipelines which may restrict the flow of the stream. In order to allow the stream to flow, a crossing structure is installed, which may be a culvert, a bridge, or a ford. These crossings also allow for stream habitat continuity, which is the continuous passage of fish and other aquatic organisms up and down the stream.

By their nature, rivers and streams are very responsive to changes in hydrology, or the movement of water throughout the landscape. This means that rivers change their course naturally over time, and that water can, and does, transport debris and sediments downstream. These characteristics can be problematic when sections of the river channel are confined to a specific path, such as a tube or tunnel. These structures can also interrupt aquatic wildlife corridors if they are not installed or maintained properly. Moreover, a damaged or undersized crossing during flood conditions can pose risks to public safety. 

Therefore, FRWA conducts routine stream crossing assessments throughout the watershed. These assessments help us understand where stream habitat is interrupted by road crossings, inhibiting aquatic migration. Badly placed or undersized culvert pipes can also be a public hazard due to their risk of failure during floods. They may eventually lead to road closures, and may become expensive for the state to maintain. The assessments are a first step in planning projects that will restore continuity, and will also be beneficial for local communities as well. FRWA wants to focus on crossings that will benefit local communities as well as the environment.

Stream crossing assessments will be conducted by our "Stream Team", made up of  FRWA staff and interns, as well as trained volunteers. We are interested in working with your community to understand which crossings are priorities in terms of highway management, flood preparedness and emergency services. The same design principles that ensure safe passage for fish and wildlife make for safer, more resilient crossings that require less maintenance.

FRWA has been funded to complete stream crossing assessments by the Berkshire Clean, Cold, Connected Partnership (BCCC), the Farmington River Coordinating Committee (FRCC) and the Lower Farmington River and Salmon Brook Wild and Scenic Committee (LFSWS). Learn more at streamcontinuity.org

Dam Removals and Retrofits

The upper reaches of the Farmington River offer abundant spawning habitat to migratory fish, but the habitat is under-used because of dams that block upstream passage.  Not every dam can be removed but FRWA is actively engaged in dam-related projects that would provide real benefits to fish and people. For instance, FRWA is a member of the River Restoration Network to help make these goals a reality.

Spoonville Dam

In 2009, FRWA received funding from the State of Connecticut (from polluter restitution payments) to coordinate an engineering study of the old Spoonville Dam in Bloomfield/East Granby. The dam, breached in 1955, pinches the river’s flow to a narrow, fast current that blocks upstream passage for migratory fish such as shad, alewife, and blueback herring as they return from the ocean and swim upstream to spawn. The engineering study concluded that the best way to restore fish passage would be complete removal of the dam, and it provided the design for removal. (Engineering study is available upon request).

Benefits of Removal

Removing these aged dams has helped to restore river flow rates and allow American shad, alewife, and blueback herring to swim up through Tariffville Gorge and access more than 20 additional miles of river. Additionally, removal has improved safety for boaters and swimmers. A historically scenic waterfall has also been recovered at a popular fishing site in place of the neglected dam.

Stakeholders

The towns of East Granby and Bloomfield have endorsed removal of these outdated dams. The whitewater paddling community benefits from the Tariffville Gorge, which lies just upstream of the dam, as it serves as the venue for world-class whitewater paddling events. The engineering study demonstrates no adverse impact of dam removal on the whitewater paddling run, except of course losing the chute through the dam breach. The gain in boater and swimmer safety was seen as offsetting the loss of this whitewater play feature. The dam owner, Connecticut Light and Power, a subsidiary of Northeast Utilities, supported the removal.

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