Replacing Risky Dam

with Natural Rapids in Frankenmuth, Mich.,

Opens up Fish Habitat

Construction of the Frankenmuth Dam Fish Passage has allowed spawning access to vital Great Lakes fish species such as Lake Sturgeon and Walleye.


Approximately 20 miles south of Lake Huron’s Saginaw Bay, the Frankenmuth Dam spans the Cass River and was originally built in 1850. Over the years, weather and continuous use deteriorated the dam, causing significant concern that the dam might fail. A failure would have had severe consequences for the Frankenmuth community, resulting in shallower water upstream, eliminating commercial boating and changing the river profile for properties along the river, as well as releasing silts and soils from behind the dam, which would damage habitat for river-dwelling wildlife.

Further, the dam prohibited spawning access to many fish species historically important to the indigenous tribes and recreational anglers in the area, including walleye and lake sturgeon, which use rivers and tributaries for spawning before returning to the Saginaw Bay where they spend most of their adult lives. The dam’s construction caused a significant decline in these species in Saginaw Bay.

The Great Lakes Restoration Initiative was able to address these concerns with the Frankenmuth Fish Passage Project. The project replaces the dam with a natural rapids, allowing fish to migrate up the river and reproduce.

Find out more about this project by watching this video produced by the Army Corps of Engineers!

Resource Challenges Addressed

  • Loss of spawning habitat
  • Riverbank stability
  • Flooding


A Walleye fished out of Saginaw Bay. The Frankenmuth Dam Fish Passage allowed Walleye and similar fish spawning access to the Cass River, which had been denied to them for over a hundred years. Credit: Drew Youngedyke

Results and Accomplishments

Removing a risky dam and replacing it with natural rapids has opened up 73 miles of fish habitat and allowed vital Great Lakes fish species such as walleye and sturgeon access to their spawning habitats, restoring their populations to Saginaw Bay.