New sea lamprey barrier construction begins this month at Little Manistee River Weir

Construction will begin the week of July 21 on a new sea lamprey barrier and trap at the Little Manistee River Weir and egg take facility in Manistee County, Michigan. The U.S. Army Corps of Engineers will design and build the project in coordination with the Great Lakes Fishery Commission, U.S. Fish and Wildlife Service and Michigan Department of Natural Resources.

The Little Manistee River Weir, which has been in operation since 1968, is Michigan’s primary egg collection site for Chinook salmon and only site for steelhead (rainbow trout) egg take. The weir underwent major renovations in 2019 to upgrade aging infrastructure; this new project will further improve the weir’s function and prevent sea lamprey from infesting 41 miles of the Little Manistee River upstream of the weir.

Sea lamprey — an invasive species that parasitizes other fish in the Great Lakes — migrate upstream in numerous Great Lakes tributaries to spawn. Barriers and traps are two of several means employed by the Great Lakes Fishery Commission to control sea lamprey populations; the other primary method of control is dispensing lampricide in streams to target larval lamprey before they metamorphose and migrate out to the lake to feed on fish. Each sea lamprey is capable of killing up to 40 pounds of fish during its feeding period, making sea lamprey control measures vital to the health of Michigan’s fisheries.

“This new sea lamprey barrier and trap will also significantly improve operations for Chinook salmon and steelhead egg collection. The new design will reduce the risk of weir failure, allow post-spawn steelhead easier movement downstream, and maintain fish passage past the weir when egg collections are complete,” said Scott Heintzelman, DNR Fisheries Division’s Central Lake Michigan Unit manager. “We know this is a popular site for anglers and paddlers, and we will make every effort to minimize the disruption of access due to construction.”

The biggest change to access site operation will be portaging around the facility. The new design extends the length of the weir structure and will remove the artificial berm on the north side of the weir structure. This means paddlers will need to portage around the facility grounds on the south side of the river. New signage and safety features will be added to ensure people are aware of the portage ahead and instructed where to exit the river. The project will not change access for those who begin their float from below the weir.

“We are excited to see this long-awaited work begin on the Little Manistee River and be completed in time to prevent migrating sea lamprey in spring 2026,” said Hannah Bashore, U.S. Army Corps of Engineers, Detroit District technical lead for the project.

The Little Manistee River Weir access site and egg collection facility will remain open to the public this summer and through the Chinook salmon egg collection. Water work activities are planned to be complete prior to egg collection in October, and construction will continue through winter. Information on specific closure dates of the Little Manistee River Weir access site will be provided on the weir’s hotline, 231-775-9727, ext. 6072, and online at Michigan.gov/Hatcheries, as necessary.

The accompanying photo is available below for download. Caption information follows.

• Little Manistee River Weir: Construction will begin the week of July 21 on a new sea lamprey barrier and trap at the Little Manistee River Weir and egg take facility in Manistee County, Michigan.