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Black Rock and Norristown Dams Fishways Final Design

The innovative design and features of the Norristown and Black Rock dams led to the return of the American Shad.
  • An aerial view of the Norristown Dam, which features innovative fish passage features  – Gannett Fleming

    Since completion, significant numbers and varieties of fish have used the Norristown Dam fishway.

  • A view of the Black Rock Dam’s Denil-Type fishway featuring close-spaced baffles in a  channel – Gannett Fleming

    The Black Rock Dam’s Denil-Type fishway featured a series of close-spaced baffles in a channel.


Montgomery and Chester Counties, Pennsylvania

Our Role
Design, Engineering.

New Construction
6 years
  • Improved fish passage efficiency
  • Reduced operation and maintenance costs
  • Significant fish numbers and varieties utilize the fish passages
  • Set a standard for future fishway facilities.

Looking for ways to implement fish passage at the Norristown and Black Rock Dams, Exelon turned to Gannett Fleming to design innovative fishways at both locations. One of the primary species affected, the American Shad, had not ascended the Schuylkill River since the 1820s when a series of dams were constructed.

The innovative designs and new technologies incorporated at the dams radically reduced operation and maintenance costs, optimized the fishways’ effectiveness, and saved the client more than $1 million. Since completion, significant numbers and varieties of fish have used each fishway, attesting the projects’ success. This included the return of the American Shad.

What We Did

Gannett Fleming provided preliminary and final design services and construction phase engineering services for the Norristown Dam and Black Rock Dam fish passage facilities on the Schuylkill River. The conceptual design studies included performing detailed site surveys and mapping, collecting and analyzing riverflow data, preparing several conceptual fishway designs, meeting with federal and state regulatory agencies, assessing permit requirements, preparing cost estimates, and summarizing findings in a study report.

Each fishway included supplemental attraction flow systems and automated gates to continuously optimize flow conditions for attracting fish into the fishway. Strategic placement of the fishway exit and flow intake structures coupled with structural grating significantly reduce clogging of the fishway from floating debris. State-of-the-art camera and recording systems monitor fish movement through the facility. The final designs provided economical and efficient Denil-Type fishway solutions at both dams that incorporate the flexibility of increasing fish passage capacity in the future.  

Key Features

  • Attraction flow intake systems that minimize clogging
  • Avoidance of historical resources during construction of the Black Rock Dam fishway
  • Fully automatic gates that regulate flow at the entrances
  • Heavy-duty grating systems that protect the structures and reduce downtime from overtopping
  • State-of-the-art, unmanned video system that records fish passing by the viewing window.

Sustainability Features & Outcomes

  • Landscaping features were incorporated into both locations
  • Restored the migratory patterns of the American Shad
  • Significant increase in fish numbers and fish variety using the dams’ fishways.

Awards & Recognition

  • Award of Merit, 2008, Association of Conservation Engineers, Conservation Project Engineering Awards
  • Diamond Award, 2010, American Council of Engineering Companies of Pennsylvania, Diamond Awards for Engineering Excellence.

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