The overall project goal is to use stream simulation design techniques to retrofit an existing barrier culvert on kirby brook, in order to restore full aquatic organism passage through the…

The overall project goal is to use stream simulation design techniques to retrofit an existing barrier culvert on kirby brook, in order to restore full aquatic organism passage through the structure, opening up an additional 1.8 miles of high quality fish habitat in kirby brook (washington, CT) and its tributaries. The target barrier culvert is approximately 50 feet upstream of the confluence with the shepaug river, one of the healthiest major tributaries of the housatonic river. Despite the structure s status as a major barrier to the upstream migration of fish and other aquatic organisms, the culvert is still in overall good condition and town of washington highway crews have reported that IT does not flood the roadway or require frequent maintenance or debris removal. Therefore, the high cost of a full structure replacement is not feasible for the town at this time, if IT is not needed to achieve multiple objectives. This makes the structure a perfect candidate for a retrofit that restores full passability for aquatic organisms. The retrofit techniques will include rock steps are installed downstream to back up water through the structure. This design will increase sedimentation, natural materials, and the depth of water through the structure and eliminate the outlet drop, fully restoring passage for fish and other aquatic organisms. The completion of this project will result in a total of over 8 stream miles of open aquatic habitat in the shepaug river and kirby brook (with even more open stream miles in the shepaug river, upstream of the kirby brook confluence). Furthermore, the completed structure will act as a regional demonstration site for an innovative stream passage restoration retrofit.