The Iowa Department of Natural Resources (DNR) has confirmed the presence of Eurasian watermilfoil, an invasive aquatic plant, at Mill Creek Lake in O'Brien County. "Preventing the spread of Eurasian watermilfoil to other lakes is the key here now," said Kim Bogenschutz, the DNR's Aquatic Invasive Species Program Coordinator, "This plant is easily spread between water bodies."Eurasian watermilfoil can spread through fragmentation.It only takes small fragments of the plant to start an infestation at another lake. The DNR plans to use an aquatic herbicide called Sonar to treat the Eurasian watermilfoil next spring. "It will take about 60 days after treatment for all the plants to die. Because of the slow action of this herbicide, we can avoid killing plants too quickly and robbing the water of oxygen that could cause a fish kill," says Mike Hawkins, fisheries biologist for the DNR. There are no restrictions on fishing or swimming with the use of Sonar, so those activities will not be affected. "It is extremely expensive to remove these types of exotic plants using chemicals," Bogenschutz said. "Sonar will kill the plants, and we have been successful in most cases in eradicating it from water bodies once it has been identified, but there is the possibility that follow up treatments may be needed in coming years." Eurasian watermilfoil spreads rapidly in a lake and can take over, crowding out more desired native aquatic plants and interfering with recreation.Eurasian watermilfoil has spread throughout much of the United States. It has been found and treated in 40 locations in Iowa. Minnesota has over 200 lakes with Eurasian watermilfoil. Anglers and boaters can help prevent the spread of Eurasian watermilfoil and other aquatic invasive species. Inspect your boat, trailer, and equipment and remove visible aquatic plants, animals, and mud before leaving a water access. Drain water from bait buckets, livewell, bilge, transom, and motor before leaving a water access. Dispose of unwanted live bait in the trash. Spray/wash your boat, trailer, and equipment with high pressure or hot water before going to other waters, ordry everything for at least five days before going to other waters.