As hydropower facilities across North America seek sustainable, cost-effective ways to meet environmental mandates, the question of fish passage at dams has never been more relevant. Recently, Underwater Construction Corporation (UCC) played a vital role in an innovative project to test a new approach to dam fish passage; one that could reshape how hydropower plants support aquatic ecosystems.
At the Tunnel Hydropower Plant in Preston, Connecticut, UCC partnered with FirstLight Power and Fishheart Ltd., a Finnish company that has developed a siphon-based fishway designed to help fish move upstream without the need for massive, expensive infrastructure. The project, part of a U.S. Department of Energy initiative, brought together international technology, local hydropower operators, and underwater construction experts to explore a better solution for fish passage.
An Innovative Approach to Dams and Fish Passage
Traditional fish ladders and bypass systems at dams can cost millions of dollars and historically required permanent, large-scale construction. Fishheart’s system, by contrast, is designed to be seasonal, floating, and mobile, adaptable to different dam environments and easy to remove, service, or redeploy.
UCC’s scope on the Tunnel Hydropower installation included anchoring the floating platform, placing concrete weights, assisting with the installation of the access walkway, and running power and data cabling to support the system’s operation. The UCC team also helped connect the entrance tubes that guide fish into the siphon mechanism, which propels them safely upstream.
Diving into the Details
While the Tunnel Hydropower installation wasn’t unusually complex from a technical standpoint, it did come with its own set of site-specific considerations. Shallow water, uneven terrain and limited boat access required careful coordination. But for UCC’s experienced four-person dive crew, these were well within scope. The team efficiently anchored the floating platform, assisted with cable runs, and supported the installation of the siphon-based fishway system.
Unlike routine dam maintenance or inspection dives, this project stood out for its environmental goals and future-forward technology. UCC collaborated closely with its longtime partner FirstLight Power and international engineers from Fishheart to bring the system online. In addition to enabling upstream fish movement, the Fishheart solution also collects valuable data through integrated AI and video analysis, tracking species, size, and migration patterns to support both utility performance and regulatory compliance.
“For us, adapting to new technologies in the water is second nature. Our team took to this system like fish to water,” said Joseph Manning, Manager, Northeast Operations, UCC. “It’s exciting to be part of a solution that could redefine how the industry approaches fish passage at dams.”
The Future of Fish Passage
After a successful pilot in South Carolina at Santee Cooper Spillway, this Connecticut installation is the first full-season deployment in North America. Another installation is already planned for a second facility in Stevenson, CT, an indicator that interest in this flexible, cost-effective approach to fish passage at dams is growing.
For UCC, the experience reinforced the value of innovation in underwater construction and environmental engineering.
“For migratory fish, dams have long been an obstacle,” said Philip McDermott, Vice President of our international operations and Northeast and Mid-Atlantic Regions at UCC. “We’re proud to contribute to a project that not only addresses this ecological challenge but also advances the sustainability of hydropower.”
Your Expert Dive Partner for Hydropower and Environmental Projects
With decades of experience supporting hydropower, dam safety, and underwater infrastructure projects, UCC continues to deliver solutions that meet complex technical and environmental needs. Whether it is traditional dam maintenance or pioneering work in fish passage systems, UCC brings unmatched international expertise and adaptability to every job. Contact our team to learn more about our full suite of services and discover how we can help you optimize your operations.
