Furnace Brook Fish Ladder Restoration

Connecticut Department of Energy and Environmental Protection

Case Name:

Housatonic RCRA Site (CT)

Country:

United States of America

Restoration Types:

Habitat Enhancement

State:

Connecticut

Affected DOI Resources:

Anadromous Fish

City:

Cornwall

Phase:

Monitoring / Completed

Project Description

Furnace Brook is a small headwater tributary of the Housatonic River that drains about 13.3 square miles in the Cornwall, CT. The brook provides important spawning habitat for eastern brook trout, rainbow trout and brown trout. Its clean, cold water is also used by trout as a thermal refuge to escape the warmer waters of the Housatonic during the summer months. Approximately 1,000 feet upstream Furnace Brook's confluence with the river, the culvert under CT Route 4 became filled with debris and rocks, blocking fish passage. The existing fishway at the culvert was installed in the 1990s but was made of wooden baffles that deteriorated over time. To improve fish passage and reduce flooding, the Housatonic Valley Association (HVA) received funding from the Connecticut SubCouncil of the Housatonic River Natural Resource Trustees to replace the existing culvert with a 120-foot long concrete box culvert and enhance the existing fishway by installing three aluminum Alaskan steeppass units to replace the wooden baffles. The new baffles were designed to maintain optimal stream velocities to allow native brook trout to easily pass through the fishway. In cooperation with the CT Department of Energy and Environmental Protection (CT DEEP) and the Housatonic Fly Fishermen's Association, HVA developed a monitoring protocol to determine the success and efficiency of passage. Monitoring was conducted during the fall migration period for brook and brown trout (mid-October through late November) prior to the restoration. For three years following the completion of the installation, HVA staff and River Stewards deployed a trap that was custom-built by CT DEEP into the fishway to monitor efficiency periodically from spring through fall. They also monitored water temperature and stream flow from loggers placed 50 feet and 200 feet upstream. Additionally, CT DEEP sampled fish at three sites upstream of the fishway in August 2015, 2016 and 2017. Six tagged brown trout that were stocked in the Housatonic River were captured at these sites along with several young-of-the-year rainbow trout, indicating that trout were spawning upstream.