VALLEY CITY, N.D. — State officials have confirmed the presence of zebra mussels in the Sheyenne River after a member of the public discovered a number of the small, invasive mussels at Little Dam, a low-head dam on the Sheyenne River near Valley City.

Michael Kjelland, an assistant professor of biology at Mayville State University, made the discovery Wednesday, Sept. 25, and notified Jessica Howell, aquatic nuisance species coordinator with the North Dakota Game and Fish Department.

Howell said it was not surprising that the zebra mussel had made its way into the Sheyenne River because its presence was confirmed earlier this past summer in Lake Ashtabula, an impoundment on the Sheyenne River in Barnes and Griggs counties in east central North Dakota.

"It was just a matter of time," Howell said.

She said some of the downsides of zebra mussel infestation are already known, including the cutting ability of their sharp-edged shells and the clams tendency to clog machinery and cluster on human-made structures.

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She said in places where zebra mussels are present swimmers should take precautions, like wearing water shoes while swimming.

Howell said other impacts are less clear, however, including what long-term effects zebra mussels may have on fish populations and algae.

Zebra mussels feed on algae that can be beneficial to the food chain while ignoring blue-green algae, a type of algae that can pose a risk to humans and animals because of the toxins they produce.

Howell said it's possible that by reducing beneficial green algae zebra mussels encourage the growth of blue-green algae, which can be dangerous to humans and animals.

Howell said the threat of zebra mussels moving from the Sheyenne River into the Red River is moot, as the entire Red River is already infested.

She underscored, however, that it is still important for people moving boats from one body of water to another to minimize the chances of transferring the mussels to uncontaminated waters.

She also provided a helpful mantra for achieving that: "Clean, drain and dry all equipment," she said.