Supporting Alewife Restoration in the St. Croix Watershed - Anadromous Fish Counts at Milltown Dam


Aquatic Ecosystem Health 

Project Description

Fish counting at Milltown Dam has been in place since 1981 and is a method of establishing an approximate count of the anadromous fish entering the St. Croix River at the lowermost dam located in St. Stephen, NB and operated by NB Power Milltown Hydro Power Generating Station (Milltown Dam). This count is the primary measure of progress in current international efforts to restore sea-run alewife, blueback herring and American shad to the St. Croix River watershed.   

The Milltown Dam has been the only location on the St. Croix River that is easily accessible to allow for the controlled counting and collecting of biological data obtained through scale sampling. With the current proposal to decommission the Milltown Dam set to begin in 2022, the increasing numbers of fish passing as counted in the last several years, and technical reports completed analyzing fish passage at Grand Falls and Woodland dams (next barriers upstream once Milltown is decommissioned) it is essential that the fish count continue. It is also key that while additional measures and next steps in continuing the fish count proceed, that this year’s contract be initiated now to take full advantage of the infrastructure in place and ease of counting at Milltown Dam, while the opportunity remains. We propose that in 2021, and until the removal of the Milltown Dam (currently anticipated to be complete in summer 2023), that the fish count include Passive Integrated Transponder (PIT)-tagging/fish movement tracking and monitoring of fish passage throughout the watershed. To achieve this and assess the efficiency of fish passage through all four (4) dams on the river, the St. Croix International Waterway Commission (SCIWC) has been granted approval by Woodland Pulp, LLC to install, maintain, and monitor tracking antenna systems in the three remaining dams in the St. Croix River, namely the Woodland Dam, Grand Falls Dam, and Vanceboro Dam.   

The SCIWC has partnered with the Peskotomuhkati Nation at Skutic to provide PIT tag reader equipment and data analysis techniques using the R Program, and the Passamaquoddy Nation at Indian Township to monitor the readers at Woodland Dam and Grand Falls Dam.   

All data collected, including fish count totals and scale sample analysis, is made available to various agencies, legislators, and involved parties to support evolving restoration plans and maintain continuity of the fish counts and these important datasets.




NB Power Milltown Dam, Main Dept/ of Marine Resources, Peskotomuhkati Nation, Passamaquoddy Nation.