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Help prevent the spread of invasive aquatic plants around West Okoboji Lake

  • 8/16/2023 7:23:00 AM
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The Iowa Department of Natural Resources (DNR) is asking for help to prevent the spread of Eurasian watermilfoil and brittle naiad around West Okoboji Lake.

The DNR continues to work with partners to develop a management plan and move through the permitting process. Boaters and other lake users must be extra vigilant when cleaning their boats and equipment to prevent the spread of these invasive aquatic plants into the main part of West Okoboji Lake or other lakes.

Eurasian watermilfoil was recently discovered in canals near Miller’s Bay and The Harbor canals on West Okoboji Lake, and brittle naiad was found in the Triboji lagoon. No Eurasian watermilfoil or brittle naiad was found in the main lake of West Okoboji or the other lakes in the Iowa Great Lakes chain.

“It is critical for boaters and anglers to clean all vegetation from boats and equipment before moving out of the canals and lagoon into the main lake to prevent the spread of Eurasian watermilfoil and brittle naiad into West Okoboji Lake,” said Kim Bogenschutz, the DNR’s aquatic invasive species program coordinator. “The same is true for boaters leaving the boat ramp at Triboji to prevent the spread to other lakes.”

The Iowa DNR Aquatic Plant Management team monitors the vegetation in the Iowa Great Lakes each year. The monitoring has been especially important this summer. East Okoboji, Upper Gar, Minnewashta, and Lower Gar Lakes were aggressively treated with an approved herbicide to eradicate Eurasian watermilfoil discovered in those lakes late last summer. The DNR worked closely with lake associations, cities, Dickinson County, and other organizations to develop and fund that treatment plan. Surveys conducted the past couple weeks found no Eurasian watermilfoil growing in East Okoboji or the three lower chain lakes.

Eurasian watermilfoil and brittle naiad are invasive rooted aquatic plants native to parts of Europe, Asia, and Africa. They can spread quickly and outcompete beneficial native plants. Eurasian watermilfoil reproduces by fragmentation, which means small pieces of it grow into new plants. Brittle naiad reproduces by seeds which float with pieces of the plant when it breaks apart.

“Boaters and anglers can unintentionally spread Eurasian watermilfoil, brittle naiad, and other aquatic invasive species if they do not take the proper precautions,” said Jason Euchner, Iowa DNR aquatic vegetation management biologist. “We always ask boaters and anglers to clean their equipment before leaving a waterbody. Now, we need them to remove vegetation before leaving the canals and lagoon and minimize their trips into and out of the canals and lagoon.”

Compliance with these requests is voluntary when moving within connected waters, but is required when leaving a water access point. It is illegal to possess or transport prohibited aquatic invasive species, such as Eurasian watermilfoil and brittle naiad, in Iowa. Boaters must also drain all water from boats and equipment before leaving a water access and must keep drain plugs removed or opened during transport.

“It’s easy to comply with the law when you follow the steps to Clean, Drain, Dry,” said Bogenschutz

  • CLEAN any plants, animals or mud from the boat and equipment before you leave a water body. With the current infestations in the canals and lagoon, you must also check boat props and other parts of the boat where vegetation fragments could get caught before entering the main lake.
  • DRAIN water from all equipment (motor, live well, bilge, transom well, bait bucket) before you leave a water body.
  • 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, high-pressure water; or Dry your boat and equipment for at least five Days.
  • Never release plants, fish or animals into a water body unless they came out of that water body and empty unwanted bait in the trash.

Find more information about aquatic invasive species and a list of infested waters in the 2023 Iowa Fishing Regulations booklet or on the DNR’s website at