SIOUX FALLS, S.D. (KELO) – The spread of zebra mussels continues in South Dakota. 

On Friday, the South Dakota Game, Fish and Parks Department announced zebra mussels were found at Roy Lake in Marshall County in northeastern South Dakota. GFP officials said a property owner found measles when removing a dock from the water. 

“We then conducted a follow-up survey and found additional mussels. Going forward we will consider Roy Lake to have zebra mussels,” Fisheries program manager Jake Davis said in a news release. “We are working with the public and GFP staff to quickly notify anglers, boaters, and other recreational users of a zebra mussel presence in a waterbody and to help educate water users.”

The GFP said a response team will place high-profile signs on access areas and engage with boaters using the infested water. 

Zebra mussels have been confirmed in more than a dozen South Dakota lakes including Lewis & Clark, McCook, Yankton, Sharpe, Francis Case, Pickerel, Cochrane, Kampeska, Dahme Quarry, Mitchell, Pactola, Enemy Swim, Blue Dog and South Rush.

On Friday, July 7, the GFP announced both Sand Lake National Refuge and the James River are considered infested with zebra mussels. 

GFP officials want boaters to clean, drain and dry watercraft to help prevent the spread of zebra mussels.