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  • Stakeholder Group Decides To Proceed With Eurasian Milfoil Treatment In Infested Areas Of West Lake Okoboji

Stakeholder Group Decides To Proceed With Eurasian Milfoil Treatment In Infested Areas Of West Lake Okoboji

August 08, 2023 Steve Schwaller

(Spirit Lake)– As we reported earlier today (Tues.), two invasive species of aquatic plants have now been confirmed in portions of West Lake Okoboji. Mike Hawkins, a fisheries biologist with the Iowa Department of Natural Resources, tells KUOO news Eurasian watermilfoil was discovered last week in Millers Bay, the harbor, the canals and in the Triboji area where a new species was also found: brittle naiad. Hawkins says he and various other DNR officials met this (Tues.) morning with a group of community stakeholders and the decision was made to proceed with a herbicide treatment of those areas, similar to what was done last year on East Lake Okoboji and the lower chain of lakes…

“The thought process there was that it’s confined to those areas right now. We’ve searched extensively on lake for it. These aren’t large areas of water or volume and so treatment really does make sense there.”

Hawkins says as of now there’s no direct evidence Eurasian milfoil is present in the main part of West Lake Okoboji, but he says it’s safe to assume it probably has…

“We almost have to assume that it has, Steve, that it has been introduced out on the main lake if it’s made it all the way to the canals on all three of those locations. It’s hard to believe it isn’t already been introduced. It either hasn’t been able to establish or if it does establish it’s sitting way below a detectable level. That wouldn’t be uncommon for a lake that has that good biological and native plant diversity because they are more able to be resilient to those types of invaders. So we think that’s probably what’s going on but to get the pressure off, get that source removed, we can definitely do some treatment in the canals.”

Hawkins says it simply wouldn’t be feasible to do the treatments in the main part of West Lake Okoboji if it does indeed become established there. The cost of treating the infested areas has been put at roughly $10,000 to $20,000.

Hawkins says because West Lake Okoboji is designated as an “outstanding Iowa Lake” means they have to go through a special permitting process before any type of herbicide or treatment is used. That means it could be early October at the earliest before any treatment could get underway. Hawkins says what may happen between now and then is a huge concern…

“Definitely and that was a lot of discussion this morning with the community group is what are some safe guards that we could put in place between now and then, between now and when we treat. We have to also remember that these plants have been in place for most likely a few months and so, you know, some of what was going to happen has happened already so, but yeah, we’re throwing out all kinds of options there.”

Hawkins says they are optimistic the treatment will be effective, siting the success they had in similar treatments made last year to East Lake Okoboji and other lakes on the lower end of the Iowa Great Lakes chain. Meanwhile officials are pleading with boaters to take even more precautions to prevent any further infestations.

Kim Bogenschutz, aquatic invasive species program coordinator for the Iowa Department of Natural Resources, said it’s critical to clean all vegetation from boats and equipment before moving out of the infested areas. She reminds everyone it is illegal to possess or transport prohibited aquatic invasive species, such as Eurasian watermilfoil, 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.

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