Shad and herring could not get past a Pennsylvania hydroelectric dam, so engineers built a fake river with rocks, slopes, and currents to trick them into continuing their migration

Migratory fish along Pennsylvania’s Susquehanna River have faced the same problem for more than one hundred years.

American shad and river herring are two species that migrate upstream as part of their life cycle. But historically, the York Haven Hydroelectric Project blocked their pathway. Fish needed a way past the dam, but the plant still needed to successfully produce electricity.

Eventually, engineers developed a “nature-like fishway.”

However, how is the nature-like fishway performing?

A dam historically standing in the way of migratory fish

Under its Federal Energy Regulatory Commission (FERC) license, the plant had to provide upstream passage for migratory fish, including American shad and river herring.

Creating the route was not going to be easy.

The river is almost a mile wide in some locations. Any solution had to handle varying flow conditions, floods, debris, ice, and environmental requirements. Engineers also had to develop the new route around an old dam that had been in operation for decades.

What appeared to be a simple fish-passage project turned out to be much larger and more complex.

Initial plans continually grew and got more complicated

The initial idea was to construct a fishway about 300′ wide within the river. The original plan was expected to require major modifications to the existing dam. As engineering designs continued to evolve and dam safety evaluations proceeded, costs skyrocketed.

The structure also had to withstand extreme river conditions and meet environmental requirements.

The Kleinschmidt Group worked closely with York Haven Power Company, federal and state resource agencies, and other stakeholders throughout the project.

Alternative options continued to be evaluated as designs evolved.

Throughout construction, Kleinschmidt helped oversee the project as the owner’s engineer.

The goal remained the same: help fish move upstream while allowing the hydroelectric plant to keep generating electricity. Additionally, the new system had to be constructed within the existing dam. That meant the fishway was being built inside an old hydroelectric facility.

They also had to work within infrastructure that was already more than a century old.

Finding a design that satisfied both requirements proved far more challenging than originally envisioned.

The nature-like fishway was constructed and completed

Ultimately, the solution was to build a new nature-like fishway. The final design was about 60% narrower than the original proposal while still meeting requirements.

Construction was ultimately completed at the York Haven Hydroelectric Project. The finished structure marked a major milestone for fish-passage efforts in the Susquehanna River watershed.

The project fulfilled a fish-passage requirement under the facility’s FERC license.

The completed system was built to provide fish passage without shutting down hydropower generation.

During construction, extremely low river flows allowed a different construction approach while still protecting water quality.

Post-construction monitoring ahead

There is no doubt from reading the available literature that the fishway was completed. It currently provides an upstream passage route for migrating fish. It also allows the hydroelectric plant to continue generating renewable electricity.

The system was intended to help fish move more freely through the river while maintaining power generation.

It was also designed to support both migratory and resident fish species.

Because the nature-like fishway was only recently completed, sufficient post-construction biological monitoring data are not yet available to evaluate the facility against its established performance objectives. The facility was constructed with defined performance objectives and a timeline for monitoring over the next few years.

This challenge will likely be faced again by hydropower operators throughout North America.

Older dams are increasingly being forced to improve habitat connectivity or continue producing renewable energy.

Projects like York Haven are not the only ones trying new ways to reconnect migration routes, and in Connecticut, engineers are testing a system designed to help migratory fish move past a dam.