Aquatic Weed Management Program

At the recommendation of the Thornapple River SAD Ad-Hoc Committee, the Township solicited bids for a multi-year aquatic weed management program, which began. in 2022. Through that process, PLM Lake and Land Management Corp was selected to develop and implement a three-year program.

2024 Weed Management Program Information

PLM surveyed the river on July 8 and determined that there was some treatment needed.  The areas were set to be treated Wednesday, July 10 but the forecast of significant heavy rain would make harvesting and treatment infeasible on that day. The treatment/harvesting will be rescheduled and there will be a 1-day swimming and 3-day irrigation restriction associated with this treatment for any properties within 100 feet of an application area (if you pull irrigation water from the river) at that time. Restriction details will also be posted on the properties the day of application.  If the upstream section of the river is ready to be harvested, that will be conducted near the end of the week of July 8th. Please monitor this webpage for updates, or subscribe to our Thornapple River SAD email updates.

Goals of River Management Program

Summarized from PLM Lake & Lake Management Corp. Letter:

Remove Eurasian watermilfoil: The primary goal of aquatic plant management in the Thornapple River is to control the growth and spread of exotic aquatic plants. Eurasian watermilfoil, a highly invasive aquatic plant species, is the predominant invasive plant found in the SAD section of the Thornapple River.

Preserve and support native species diversity: Growth of native plants that support the Thornapple River fishery (by creating structure and habitat) will be encouraged, provided they do not excessively interfere with recreational uses of the river (e.g., swimming and fishing) in high-use areas.

Manage aquatic cover (native and invasive): In areas of the SAD where native aquatic plants reach recreational nuisance levels, management techniques that reduce the height of these plants without killing them (e.g., harvesting, contact herbicides) will be used whenever possible. Specific areas will be set aside where native plants will not be managed to provide habitats for fish and other aquatic organisms.

Please note: PLM Lake & Land Management Corp. does not manage or monitor levels of PFAS (Per- and Polyfluoroalkyl substances) in the Thornapple River. For more information on PFAS, visit the Township's PFAS webpage.


  • Herbicide and Algaecide treatments
  • Mechanical harvesting (removal) of nuisance species
  • Water quality analysis
  • Conduct pre- and post-treatment surveys
For more details, please read PLM's Letter to the Township for the 2024 season.

If you have any questions about the program, contact Township Manager Jade Smith at or by phone at 616-949-1500.