Jun. 11—Officials first identified zebra mussels in Lake Ashtabula three years ago and the invasive nuisance species has thrived there ever since, according to Rich Schueneman, resource manager at Baldhill Dam.
And the situation there may continue to get worse.
"It is hard to say," Schueneman said. "We are early in the population of zebra mussels here. They are attaching to docks and buoys and other structures."
They have even been noticed on the gates used to control releases from the dam, although not at high enough levels to affect the dam's operations.
"We won't see for a number of years how that plays out," Schueneman said.
How quickly the population of zebra mussels in Lake Ashtabula has grown is a cause for concern, according to Ben Holen, aquatic nuisance species manager for the North Dakota Game and Fish Department.
"A lot of lakes in North Dakota have similar water chemistry," he said. "If they (zebra mussels) were introduced into Jamestown Reservoir or Pipestem Dam, they would thrive just like they are in Ashtabula."
Zebra mussels are mollusks about the size of a fingernail native to Europe and Asia. The species was introduced to the United States when ballast tanks from European ships were drained. The species has spread over the central United States. In North Dakota, zebra mussels have been found in Lake Ashtabula, Lake LaMoure and the Red River where they are thriving, Holen said.
"Containment is the big goal," he said. "You can't eradicate zebra mussels on large waters like Ashtabula."
North Dakota Game and Fish has 17 officers now dedicated to inspecting boats that leave infected waters to make sure that there is no water or vegetation transferred from the Ashtabula or LaMoure lakes to other bodies of water in the region.
However, most of the responsibility rests on the boat owners.
"Make sure boats and trailers are completely dry," Holen said. "Keeping a boat dry and out of the water for a week or more is best."
Holen said mature zebra mussels attach to objects in the water. What he described as "villagers," microscopic young mussels, can be spread even in water in a bait tank or boat motor cooling system.
Along with causing damage to docks and dam structures, the mussels consume nutrients in the water ultimately damaging the fishing resource of the lake.
The nutrient levels in area North Dakota lakes are so high the mussels could reproduce two generations in a single summer, Holen said.
"That would take a lot of food that would support fish," he said.