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Weed Culture

Our lakes (Minocqua & Kawaguesaga) have a very healthy weed culture in that we have over fifty different species of aquatic weeds.  A good weed culture is very important for a good fish culture since the weeds provide space for small animals that become food for the food chain.  The weeds also provide “cover” for fish allowing them to go about their business with a smaller risk of becoming a meal for a bigger fish. Additionally, we have two to three weeds that cannot exist if the chemical composition of the water is not acceptable.  These weeds are the “canaries in the coal mine” for lake pollution.  Since they are thriving in our waters, we are doing just fine as to water pollution.   However, there are invasive weeds in our lakes and we must constantly work to be sure they do not explode and ruin our waters.  These weeds are our Weed Threats.


Weed Threats

Currently there are three known invasives in our lakes –

  • Eurasian watermilfoil– will never be eradicated with known procedures and technology
  • Curley leaf pondweed – we have ignored it to date, seems to be “in balance”
  • Purple loosestrife– treat with herbicides and beetles

We have received substantial grant money from DNR for aquatic invasive control – we are in process of applying for another 5 year grant.  The project costs at least $40,000/year.

The Invasive Yellow Iris is a growing concern.  This showy garden/pond ornamental that has escaped to become an aggressive wetland invader.  It spreads by roots and seed, quickly forming dense stands that displace the native plant and wildlife species.


The Battle With Eurasian Watermilfoil

The Board of Directors was familiar with Eurasian watermilfoil well before it was discovered in Minocqua Lake.  Its reputation was frightening for anyone owning property near a lake.  Stories were widespread about the infestation of lakes in the Madison area, Minneapolis and many other locations.  In the early 2000’s it seemed like there were no stands of EWM anywhere near Minocqua and Kawaguesaga, consequently the Board did not begin boat inspections. (The way to prevent infestation is to keep boats from transferring it into a lake.  So, boat inspections are the only way to stop its spread though they are not 100 percent effective.)In June of 2001, Eurasian watermilfoil was discovered in Kennedy Bay (Minocqua Lake) at the boat landing near the Minocqua Library.  Divers were immediately employed to pull and bag as much as possible.  We were convinced we had stopped this infestation in its tracks.  Unfortunately, in 2002 the EWM reappeared, and we again employed divers to pull and bag.  The next year, herbicide was used for the first time in the general area of the boat landing in Kennedy Bay.  The treatment was not sucsessful and a one-time emergency permit was granted to retreat. The retreatment seemed to help, but was not totally satisfactory.


Using Herbicides

The herbicide of choice for EWM in the past was 2,4-D.  Advancements in technology and science has now directly MKLPA and it’s agents to use ProcellaCor.  In order to gain the DNR’s permit to put chemicals in the lakes MKLPA must follow a detailed protocol. Basically, the protocol calls for surveys both in the fall and the spring by trained personnel.  The patches of EWM are identified and the perimeter established with GPS coordinates.  Next, the plot area is computed using the GPS coordinates.  Lastly, based on the total area of a plot, the biologist must sample a specified number of locations using a rake drop or now, a TV camera.  There are three levels of density reported 1, 2 and 3, with 3 being the most dense.  Only patches with a 2 or 3 density are considered for treatment. 

An application for treatment is submitted to the DNR during the winter and the treatment sites are reconfirmed in the spring audit.  The DNR then grants a treatment permit for the sites they feel merit attack and they specify the dosage level allowed.  The chemicals are applied by a licensed applicator when the bottom water temperature reaches 53 degrees F.  Generally, treatment will not be approved after the beginning of June in any year. The reason for the early application is an attempt to minimize herbicide damage to the “good” plants.  Since EWM is usually the first weed off of the bottom, our desire is to knock it down before the others start to grow.  Various treatment locations and dosage levels have been used since herbicides were introduced in 2003.

Treatment Methods Currently in Use.

Three treatment methods were used in 2009 and continue to this day:

  1. herbicide 2,4 (added starting 2019 ProcellaCor)
  2. weevils (E Leconti)
  3. snorkel/scuba diving 

For more detail on the Association’s management of Eurasian watermilfoil go to the State of the Lakes section.