Rock reef fish spawning habitat restoration underway in Saginaw Bay

It’s been more than 20 years in the making, but this month a fish spawning habitat restoration dream becomes a reality for Saginaw Bay. The DNR and Department of Environment, Great Lakes, and Energy have built a coalition to restore a 2-acre rock reef at the Coreyon Reef site, about 11 miles northeast of the mouth of the Saginaw River.

The restoration project focuses on the trailing edge of a historic rock reef complex that existed naturally in the bay until it was heavily degraded by sand and sedimentation from long-standing erosion in the watershed.

Restoration efforts began this month and should be completed by early fall. Once done, the restored reef will be roughly 2 acres and reach a peak of about 5 feet off the bottom in 18 feet of water. The rock, placed by Great Lakes Dock and Materials, LLC from Muskegon, is crushed limestone and glacial cobble. In all, approximately 22,500 tons of rock will be used to build the reef, carefully placed in precise positions and dimensions by barges and cranes.

“Many fish species use critical and limited rocky habitats, like cobble and gravel, to spawn on because it can protect their eggs from predators and ensure they get enough oxygen to incubate,” said Dave Fielder, a DNR fisheries research biologist.

“Walleye, lake whitefish and lake trout are expected to benefit the most from this habitat restoration – but other fish may use the reef, including cisco, which are being reintroduced in the bay through a new stocking program, or smallmouth bass,” Fielder said. “We hope the reef restoration will promote a more resilient fish population for the future.”

Principal funding for the project came from a $980,000 U.S. Environmental Protection Agency grant, with funds originating from the Great Lakes Restoration Initiative. The final project total is $1.379 million and includes $25,000 from the Saginaw Bay Watershed Initiative and various agency funds from within EGLE.

Questions? Contact Dave Fielder (DNR), 989-356-3232, ext. 2572 or Bretton Joldersma (EGLE), 517-256-1773. For more information on this project, including a list of involved partners, visit