The Department of Natural Resources has confirmed that zebra mussels were found at the Moorhead pumping station intake on the Red River, Moorhead Public Service announced Tuesday, May 24.
The zebra mussels were discovered during routine maintenance on pumping equipment.
The discovery of adult zebra mussels comes nearly one year after an adult zebra mussel was found on an intake screen at the Fargo Red River intake.
In 2013, MPS completed modifications to the Red River Pumping Station, which included adding an intake screen composed of a zebra mussel repellent alloy.
A routine inspection completed in March showed no zebra mussels attached to the intake screen, water plant Supervisor Kevin Young said.
With discovery in the Red River, some push for more action on zebra mussels. But the zebra mussels were recently found on pumping equipment, Young said.
“It’s been a concern for a while,” he said Tuesday.
In addition to the mussel-repellent screen, MPS could also use chemical products to control zebra mussel infestations, Young said.
He said if the mussels start attaching to the intake screen, or get into the pipe to the pump station, they could reduce water intake flows.
“It’s been something we’ve been monitoring for quite some time,” Young said. “There are other communities in Minnesota that have zebra mussel infestations. It’s not an entirely new thing, but it’s something to keep an eye on.”
Zebra mussels were found on the screen to Fargo’s Red River water intake in early July 2015.
In August 2015, the North Dakota Game and Fish Department instituted two emergency rules on the Red River to help prevent the spread of the invasive species beyond the river.
Anglers could no longer transport live bait in water away from the Red River and all boats and watercraft are required to have plugs pulled when exiting the river.
According to the Minnesota DNR’s website, zebra mussels are small, fingernail-sized animals that attach to solid surfaces in water.
Adults are ¼ inch to 1½ inches long and have D-shaped shells, often with alternating yellow and brownish colored stripes. Female zebra mussels can produce 100,000 to 500,000 eggs per year.
These develop into microscopic, free-living larvae (called veligers) that begin to form shells.
After two to three weeks, the microscopic veligers settle and attach to any firm surface.
Zebra mussels are native to Eastern Europe and Western Russia and were brought over to the Great Lakes in the ballast water of ships. Populations of zebra mussels were first discovered in the Great Lakes in the late 1980s.
Zebra mussels can be a costly problem for cities and power plants when they clog water intakes, the DNR says. Zebra mussels also cause problems for lakeshore residents and recreationists by attaching to boat motors and boat hulls, reducing performance and efficiency; attaching to rocks, swim rafts and ladders where swimmers can cut their feet on the shells; and clogging irrigation intakes and other pipes.
Zebra mussels eat tiny food particles that they filter out of the water, which reduces available food for larval fish and other animals, and causes aquatic vegetation to grow as a result of increased water clarity.
Zebra mussels can also attach to and smother native mussels.
MPS is a community-owned utility serving the residents of Moorhead with electricity and water.