DNR to move mussels for bridge project

TOWN OF ST. JOSEPH (AP) - Crews will have to move thousands of mussels in the St. Croix River as part of the bridge project connecting Minnesota and Wisconsin.

The more than 7,000 mussels will include three species that are protected or endangered and that play an important role in the river's health, according to the Milwaukee Journal Sentinel.

Divers will take the mussels upstream this summer, said Lisie Kitchel, a conservation biologist and mussel expert with the Wisconsin Department of Natural Resources. She expects it will cost about $50,000.

"The water's pretty clear in the St. Croix," Kitchel said. "It's very sandy and you just kind of comb your fingers through the sand until you find a shell."

Kitchel said the divers will move about 15 species, including the protected mussels, which are filter feeders and play an important role in consuming algae and provide a source of food for other aquatic life.

"They tend to be found in beds with good diversity, so we take everything to maintain that diversity," she said

The mussels will be transferred to a suitable bed upstream in the hopes of protecting species such as the Higgins eye, which today can be found in only about 50 percent of its historic range, according to the Fish and Wildlife Service.

Mussel populations have dropped because of pollution and sedimentation in many rivers. Because three of the mussels in the river are protected, authorities are legally bound to take steps to ensure their safety, particularly for the Higgins eye, a federally endangered species, according to Kitchel.

The beds for the Higgins eye mussel downstream at Prairie du Chien, once one of the richest sources of the species, have been decimated by the teeming zebra mussel populations, according to the U.S. Fish and Wildlife Service.

The St. Croix Crossing project will replace the 80-year-old Stillwater Lift Bridge with a four-lane bridge that will connect expressways on both sides of the St. Croix River. According to estimates by Wisconsin and Minnesota officials, the project is expected to cost $580 million to $676 million.

Some of protected mussels are likely to be killed during construction, the DNR announced this month. The agency said it was authorizing an "incidental take" of the Higgins eye, butterfly, a state endangered species; and buckhorn, a state threatened species.