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Aggressive treatment planned for Eurasian watermilfoil found in Lost Grove Lake

  • 6/13/2023 1:16:00 PM
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DAVENPORT - The Iowa Department of Natural Resources (DNR) will start treating Lost Grove Lake at the end of June with the approved aquatic herbicide Sonar A.S. to eliminate Eurasian watermilfoil.

Sonar A.S. has successfully eradicated Eurasian watermilfoil from other lakes in Iowa by preventing the plant from producing a pigment needed for photosynthesis, starving the plant over several weeks. The herbicide has no restrictions for swimming, fishing, irrigation, or drinking water at the planned dose. 

Treatment will continue for eight weeks. DNR biologists will test the water throughout the treatment every two weeks to measure concentration of the herbicide and prescribe “bumps” of herbicide to maintain the herbicide concentration. 

“The herbicide is effective at very low concentrations”, explains Jason Euchner, Aquatic Vegetation Management Biologist for the DNR. “We will treat the lake at 5 parts per billion. 

Eurasian watermilfoil was discovered in the Lost Grove Lake in mid-May. This aggressive invasive plant is known to outcompete native plants and take over areas of a lake. It can spread easily from lake to lake if boaters and anglers do not take the proper steps to help prevent the spread.

Clean, Drain, Dry is a simple three step process that boaters need to follow every time they move from one body of water to another.

  • CLEAN any plants, animals, or mud from your boat and equipment before you leave a waterbody
  • DRAIN water from all equipment (motor, live well, bilge, transom well, bait bucket) before you leave a waterbody.
  • DRY anything that comes into contact with water (boats, trailers, equipment, boots, clothing, dogs). Before you move to another waterbody either: Spray your boat and trailer with hot or high-pressure water; or Dry your boat and equipment for at least five days.
  • Never release plants, fish, or animals into a waterbody unless they came out of that waterbody and empty unwanted bait in the trash.

It is illegal to possess or transport prohibited aquatic invasive species like Eurasian watermilfoil. It is also illegal to transport any aquatic plants on water-related equipment in Iowa. Signs posted at public accesses remind boaters to stop aquatic hitchhikers and identify infested waters. Boaters must also drain all water from boats and equipment before they leave a water access and keep drain plugs removed or opened during transport.

Find more information about aquatic invasive species and a list of infested waters in the current Iowa Fishing Regulations or at