Enhancing Fish Passage: Haley’s Brook Crossing

The Town of Groton is undertaking a feasibility study to improve fish passage at the Haley’s Brook crossing on River Road. This road-stream crossing has been identified as a moderate barrier to aquatic connectivity, limiting the movement of migratory fish and contributing to habitat fragmentation. Save the Sound has highlighted this location as one of Groton’s highest-priority restoration opportunities due to its substantial ecological benefit potential.

The existing culvert creates high water velocities and a perched outlet during low flows, both of which inhibit fish from accessing upstream habitat. Improving this crossing would reconnect approximately 2.3 miles of high-quality upstream habitat, supporting native fish species and enhancing overall watershed resilience.

The Town is partnering with The Nature Conservancy to evaluate alternatives that restore fish passage while also addressing flood risk and infrastructure needs at the site. The preferred alternative will be advanced to the concept design phase. Project findings and recommendations will be shared with the community through public meetings, supporting transparency and local engagement in habitat restoration efforts.

Did you Know? Understanding the Science of Haley’s Brook

• Fish Passage & Connectivity: Think of this as a "clear highway" for fish. When a stream has high connectivity, fish can travel freely to find food, cool water, and places to spawn.

• Perched Outlet: This happens when a culvert pipe sits higher than the water level below it, creating a small "waterfall." Most local fish cannot jump high enough to enter the pipe, so they get stuck.

• Habitat Fragmentation: This occurs when structures like roads break a natural area into small, isolated pieces. Fixing this crossing "mends" the fragment so the ecosystem can work as one again.

• High Water Velocity: When a pipe is too narrow, water shoots through it like a fire hose. This creates a "velocity barrier"—the water simply moves too fast for fish to swim against it.