Spoonville Dam Removal and Winchell-Smith Fishway

Princeton Hydro initiated engineering assessment and completed final design for the Farmington River Watershed Association and its project partners for this exciting, fast-paced fish passage improvement project, which included both the removal of the Spoonville Dam and the design of a nature-like fishway at the Winchell-Smith Dam.
The Farmington River is a renowned Wild & Scenic River in Connecticut and this project looked to improve fish passage for historic runs of diadromous fish at both sites.

The Spoonville Dam, a 35-foot-high concrete dam that was partially breached during the historic 1955 floods, is the first partial barrier to fish passage on the Farmington River. The dam is located in the Tariffville Gorge, just downstream from an outstanding whitewater rapids heavily utilized by whitewater enthusiasts. A transparent design process and open lines of communication with whitewater boaters were critical parts of the development of the final design, in order to ensure project buy in from the key project stakeholders.

The second barrier on the Farmington is the Winchell-Smith Dam. The Winchell-Smith Dam is a low head timber crib dam that had already lost the upper two to four feet of the dam in previous high flow events. The dam currently provides a well-known scenic overlook from the dam’s mill that has been converted into a popular local restaurant. Site aesthetics were a critical design component and the design approaches needed to be approved of by the dam and restaurant owners.

Princeton Hydro was initially tasked with designing a bypass channel around the dam but found during our geotechnical field investigation that the overbank area was dominated by collapsible soils which could potentially cause an unintended channel avulsion and dam circumvention if the bypass channel was constructed. We then proposed a partial rock ramp fishway extending in an upstream direction from the dam in order to minimize cost while maximizing the site’s fish passage effectiveness based on the target fish species’ behavioral needs.