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A Case for Responsible Aquatic Weed Control – Contact the DNR

Do it Yourself” aquatic weed control is being offered in Wisconsin and around the Chain O’Lakes by companies located outside of Wisconsin.

Please note: In Wisconsin, a permit is needed for any chemical aquatic plant management. It is Illegal to apply chemicals on, in or near the water without a permit from the DNR.

Chemicals, or chemicals improperly applied, can harm or kill critical native aquatic plants, amphibians, fish and birds. Some chemicals can remain in the lakes for weeks before dissipating.

We realize that some may want to remove aquatic plants on shorelines and lake beds, however, please remember, these plants are essential components to the health and balance of our lake’s ecosystem.

Aquatic plants play a vital role in:

- oxygen production

- habitat provision – (fish, birds, amphibians, insects and other critters)

- nutrient cycling

- sediment stabilization

- water filtration

- and let’s not forget aesthetic value

Paul Skawinski, UW-Stevens Point - Extension Lakes:

"Any pesticide applied to the water requires a permit with the DNR. A primary reason for this is to make sure that the herbicide being used even makes sense for the intended goal. Different herbicides target different types of plants. Using the wrong chemical can be a waste of money and have unintended consequences, and may have no effect on the intended "weed" target."


"Some glyphosate formulations are toxic to amphibians - another reason to seek a permit so that the appropriate formulation can be used where it's needed."


"DIY" herbicide treatments are not a good idea. Most people do not understand how to apply these correctly, when to apply them to be effective, which chemical to use, or how much to apply (too little or too much can both be ineffective). Again, that's why the permitting process is essential."

Ted Johnson, DNR, Lake Biologist, Waupaca area

"In almost all situations, riparian owners are prohibited from applying their own aquatic herbicides in or near the water along their property.  If any individual riparian owner would like to apply pesticides themselves, they should reach out to me, Ted Johnson, DNR- Lake Biologist, with their specific plans to get more information.  In all likelihood, they will be required to hire a DATCP certified aquatic pesticide applicator to do the work.  As mentioned above, even if someone falls under the exemption to apply the pesticides themselves, a permit is required."

As a follow up, I asked Chris Hamerla, Regional Aquatic Invasive Species Coordinator at Golden Sands, last two important questions:

What if the treated lake water was used to irrigate yards or gardens,  

“Referring to unregulated applications (vs DNR permitted applications) I really don't know the chemistry, but it likely depends what type of chemical and how much was used, perhaps it may affect the lawn, flower beds, garden or whatever was watered”. 

What if someone was swimming in improperly treated lake water:  

“Not knowing what chemical was used and how much, I wouldn't want anyone swimming in it.  We all know we get water in our mouths while swimming.  Pets are going to drink it.  Wildlife is going to drink it.  Fish and amphibians are living there.  There are many other critters and reasons to be worried about improper application but the above should be good enough for a responsible person to realize they shouldn't be doing this”. 

To safeguard the well-being of our land, lakes, wildlife and community, we strongly discourage the use of "do it yourself" aquatic herbicides

If you have aquatic weed issues that you feel needs attention, please reach out to Ted Johnson -DNR, his expertise ensures a safe and effective resolution for everyone.

Phone (Cell): (920) 362-0181

The WCOA- Stewardship Committee would like to THANK Paul Skawinski of UWSP Extension Lakes, Ted Johnson DNR – Lake Biologist, and Chris Hamerla, Regional Aquatic Invasive Species Coordinator at Golden Sands, for their expertise and contributions.


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Waupaca Chain O'Lakes Association

Stewardship and Resources Committee

Chair(s): Julie Mazzoleni, Fawn Johnson


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