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The federal government is proposing to designate portions of some Minnesota and Wisconsin rivers as critical habitat for endangered freshwater mussels. 

The proposal by the U.S. Fish and Wildlife Service includes portions of the Mississippi and St. Croix rivers. They are home to three mussels species with unusual names: sheepnose, spectaclecase and snuffbox, named for their physical appearances.

The hard-shelled mollusks are “the livers of the river,” said Nick Utrup, a biologist with the Fish and Wildlife Service. They filter large amounts of water and help remove sediment and pollutants.

“One mussel can clean 10 gallons within just a few minutes,” he said. “Once you have a bunch of mussels, it’s basically a filtering mechanism and cleans the river.”

Mussels also provide food for other aquatic creatures, and are good indicators of a river’s health.

Freshwater mussels were once abundant throughout Minnesota's waterways. But their populations have declined due to habitat loss, pollution, dam construction and competition from invasive species.

Last fall, the Fish and Wildlife Service announced a recovery plan for the three native mussel species, plus a fourth — the rayed bean — not found in Minnesota. All four were listed as endangered in 2012 under the Endangered Species Act.

It’s now proposing to designate 3,974 river miles as critical mussel habitat. The designation will help guide federal restoration efforts, but does not restrict private development activities, Utrup said. 

. The public comment period is open until Feb. 11.

Biologists with the Fish and Wildlife Service, National Park Service and other agencies have been 

 dwindling populations of native freshwater mussels to the St. Croix and other rivers. They collect pregnant female mussels, harvest their larvae, expose them to a host fish, then return the female mussels back to the river.

“That is usually our first step in conservation, because that’s almost like putting your thumb on the dam, basically, and trying to stop the flow a little bit,” Utrup said. 

Other restoration efforts under consideration include removing dams and planting buffer strips along rivers to prevent pollution.

Utrup said mussels are “out of sight, out of mind” for most people, but their role shouldn’t be underestimated.

“They provide just immeasurable benefits to the river ecosystem,” he said.

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Kirsti Marohn

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Freshwater mussels were once abundant throughout Minnesota’s waterways. But their populations have declined due to habitat loss, pollution, dam construction and competition from invasive species.

‘Livers of the river’: Feds propose designating rivers as critical habitat for freshwater mussels

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