Water quality and fish passage are key concerns
New Haven, CT – Three environmental organizations are asking the federal government to regulate the Rainbow Dam, located in Windsor, CT, to help stop ecological harm.
The Rainbow Dam blocks off 96 percent of the Farmington River watershed to the migration and movement of many aquatic species, including American shad, river herring, American eel, and sea lamprey. In 2024, the Farmington River was named one of America’s Most Endangered Rivers due to the Rainbow Dam’s impacts: increasing toxic algae blooms, blocking fish passage, modifying flows, and impairing recreation.
This dam is not currently regulated by the Federal Energy Regulatory Commission (FERC)—which helps ensure adequate fish passage and protects water quality and flows, among many other things—even though its operation as a hydro-electric dam on a navigable river should subject it to such regulation. The lack of federal regulation of the Rainbow Dam has meant that the dam has not been held to the same standards as other hydro-electric dams in Connecticut, and has been allowed to operate without safe, timely, and effective fish passage; portage around the dam for recreational boats; or flows and water quality suitable to maintain a healthy river system and habitat for native aquatic species.
“The Rainbow Dam has long evaded FERC regulation, to the detriment of the Farmington River,” said Jessica Roberts, Save the Sound’s Connecticut staff attorney.
Save the Sound is seeking to change that. However, FERC must first make a formal finding that it has jurisdiction over the dam.
In November, Save the Sound, American Rivers, and the Farmington River Watershed Association submitted a request to FERC for updated jurisdictional determination. The request is available here.
In response, FERC has begun investigating the jurisdictional status of the Rainbow Dam. Information is here.
Now, the public has the opportunity to weigh in on whether the Rainbow Dam is subject to FERC’s jurisdiction. FERC is soliciting comments, protests, and motions to intervene until February 20, 2026, at 5:00 p.m. EST. Anybody may file comments with FERC electronically. For information on how, please see this guide.
While any comments are welcome, those on the jurisdictional status of the Rainbow Dam will be most helpful to FERC in making its determination. Some factors that FERC considers in evaluating its jurisdiction include:
- Whether the Rainbow Dam is located on a navigable water of the United States. To make this determination, FERC will consider whether the Farmington River was historically used to transport goods or people, or whether people can paddle or have paddled down the Farmington River in a canoe, kayak, or other boat.
- Whether there has been construction on the Rainbow Dam since 1935 that has increased its water storage or generating capacity.
“There is ample evidence that the Farmington River is navigable. Historically, this river was used as a ‘water highway’ to transport ship masts from Connecticut to New York and the West Indies,” said Jessica Roberts of Save the Sound. “Now, companies such as Metacomet Tours regularly offer guided canoe and kayak trips down the Farmington River, and in May 2025, Save the Sound, American Rivers, and the Farmington River Watershed Association conducted our own ‘float test,’ where staff paddled canoes and kayaks from the base of the Rainbow Dam to the Connecticut River. All this clearly shows that the Farmington River, at least from the base of the Rainbow Dam to the Connecticut River, is navigable. We urge FERC to take this evidence into consideration in making an updated jurisdictional determination.”
“The Rainbow Dam is over a century old and like many dams across the country, over time, its facility has degraded. We need the company to bring its facility into compliance with applicable state and federal laws, including providing safe, timely, and effective fish passage, providing necessary recreational amenities, and abiding by state flow standards,” said Andrew Fisk, northeast regional director for American Rivers.
“The Rainbow Dam should be regulated by FERC, just like other hydroelectric dams on the Farmington River and in the State of Connecticut,” said Aimee Petras, executive director of the Farmington River Watershed Association.
For more information regarding the factors that FERC uses to make its jurisdictional determination, see the Notice of Pending Jurisdictional Determination here.