Lake, Dam & Spillway – Pondweed Update

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Lake, Dam & Spillway – Pondweed Update

2019 Indian Hills Pondweed

In conversations with other lake associations, biologists, and conservation departments, pondweed is expected to be a problem again this year. The large majority of lakes in Missouri, Iowa and Kansas are experiencing an explosion in Pondweed again this year.  We have talked to several conservation agencies and this is what they are saying is the cause:

  • Significant emergence of pondweed last year has allowed the root system to re-sprout this year regardless of treatments.
    • Herbicide treatments are effective for a season much like the herbicides you have to use yearly to treat for crabgrass in your yard.
  • Higher temperatures caused warm water conditions, fuel Pondweed growth again this year in multiple states.
  • Other factors include, number of sunny days, shallow water depths and migratory waterfowl.

American pondweed- Variable leaf pondweed, Split leaf pondweed

  • Variable leaf pondweed produces very small leaves only after reaching the top of the water surface.

Current Pondweed Strategy:

We have a multi-prong approach for dealing with the Pondweed and continue to survey growth rates and strategy effectiveness:

  1. Grass Carp:  Last year we stocked the lake with approximately 400 Grass Carp. Grass Carp will eat three time their own weight each day. This is the first part of our approach and will help stabilize/reduce the current growth and provide a long-term control.
  2. Chemical Treatments: There are herbicides we can use to address the issue quicker than Grass Carp and we have been testing a site-targeted herbicide that ensures the safety to our lake, members (including kids), fish/dogs and our significant investment in grass carp.
    1. Results of herbicide treatments – The results have been extremely positive and we are seeing a 90 to 95% kill rate in targeted areas, but to use this method widescale we will need additional funding that our current budget does not have.


 We will continue to keep our members up to date on our progress to address the problem we are experiencing.  Should you have any questions please send them to the ILPOA Office at


Bill Brumitt

ILPOA Chairman Lake, Dam & Spillway