Housatonic Valley Watershed Concept Planning & Geomorphic Design

Princeton Hydro partnered with the Housatonic Valley Association (HVA) in their long-term effort to support municipal flood hazard mitigation planning, improve flood resiliency of transportation infrastructure, and remove barriers to aquatic organism passage in northwestern Connecticut. HVA deployed teams of trained volunteers to inventory road-stream crossings at multiple sites following protocols developed by the North Atlantic Aquatic Connectivity Collaborative.

Princeton Hydro assisted the HVA and other project partners including Connecticut Department of Energy and Environmental Protection, University of Connecticut, and Tufts University in identifying the highest priority road-stream crossings to accomplish the multi-faceted goals.

Our role was to train HVA staff on survey and data collection of the road-stream crossings to support the re-design of the road culverts following the U.S. Forest Service Stream Simulation for Aquatic Organism Passage (AOP) at Road-Stream Crossings. This approach utilizes a detailed assessment of the stream geomorphic conditions, including dimensions, pattern, and profile. It also examines bedforms (pools, riffles, runs, steps), substrate grain size, large wood, and then recreates (or simulates) that channel design through the crossing. The approach has been used with great success throughout the National Forest system, with multiple AOP culverts withstanding large hurricanes while nearby conventional crossings fail.

Princeton Hydro successfully applied the design approach at road-stream crossings in Pennsylvania and Massachusetts. Then, our team developed preliminary designs for eight road-stream crossings, which have been incorporated into municipal flood hazard plans.