Noroton River Culvert Fishway

Princeton Hydro was hired to design this fish passage project along the Noroton River through a long, perched three-barrel concrete culvert under Interstate-95 for Save the Sound (formerly Connecticut Fund for the Environment).  At the start of the project, the culvert was in good shape with adequate capacity, so options relating to its removal or replacement with an opened-bottomed structure were not feasible. This culvert is the first primary barrier to diadromous fish species along the Noroton River. Princeton Hydro’s design creates a rock ramp fishway at the downstream end of the culvert to overcome the four-foot head differential. The lower flows and fish passage flows are fully directed to one of the culvert barrels, using a fixed-crest concrete weir constructed upstream of the culvert entrance, blocking off flows to the two additional culvert barrels. The concrete baffles and fixed concrete weir were selected to eliminate the need for the seasonal maintenance that would have been associated with more mechanically complex alternatives such as hinged flashboards and wooden or aluminum interior baffles. 

The project was funded by state grants and incorporated significant input and collaboration with fisheries biologists at CT Department of Energy and Environmental Protection, Diadromous Fisheries Division, as well as the client. In addition, the project required coordination and support from CT Department of Transportation (DOT) due to its manipulation of an interstate highway culvert. Careful calculations needed to be made and reviewed with CT DOT to ensure that the culvert’s flood capacity would not be negatively impacted.