2020 Potential Eurasian Water Milfoil Treatment

Posted by Crystal Lake Improvement Association
3 months ago | April 29, 2020


Update: June 1st 2020

Eurasian Water Milfoil Treatment Suspended

The City of Burnsville recently had a survey of the weeds on Crystal Lake conducted.  One of the invasive species surveyed,  Eurasian water milfoil (EWM), was found at low levels that do not warrant treatment at this time.  

No action is necessary by lakeshore owners at this time and thank you to those property owners who notified the CLIA of their preference to “opt out” of any EWM treatment near their shoreline.

The CLIA’s vendor plans to monitor the EWM levels to determine if treatment may be appropriate later this summer.  If the CLIA does decide to treat EWM on Crystal Lake this summer, lakeshore property owners will be notified again so that they may “opt out” of treatment near their shoreline.

Additional background

Similar to 2019, lakeshore owners were notified of a potential EWM  treatment for 2020 that was not conducted.  The CLIA recognizes that numerous communications on algae and weed management matters can be confusing and appreciates members’ patience and understanding.  One of the challenges of treating this aquatic invasive species is timing, in that there is little time between accessing whether EWM should be treated (or not) and when the treatment should be applied (if applicable).  Thus, as much preparation as possible was conducted in advance in order to meet the DNR’s permit requirements, including notifying lakeshore owners about this potential (though presently unnecessary) treatment.  

It appears that the EWM on Crystal Lake has been a bit of an anomaly in that once EWM is found in a lake, it typically expands.  It’s unclear why the EWM on Crystal Lake hasn’t expanded as much as anticipated though there’s speculation that it may be due to competition from other plants and that this growth could be cyclical.


The Crystal Lake Improvement Association (CLIA) may treat Crystal Lake in late May or June to combat the aquatic invasive species, Eurasian water milfoil (EWM). This potential treatment is dependent upon the results of an upcoming weed study conducted by the City of Burnsville. If it is determined that a treatment of EWM is warranted, the CLIA may use the herbicide ProcellaCOR, Diquat, or Triclopyr (or a combination of these herbicides).

Opting Out

If Crystal Lake property owners would like to “opt out” so that EWM isn’t treated along their shoreline, please email the CLIA by May 22, 2020 at CrystalLakeMN@gmail.com.  

Please include:
  • name,
  • property address, and
  • description of the location of the property. 
Additional EWM Background
Effective and Responsible Treatments

In 2019 the CLIA similarly considered treating EWM in Crystal Lake but after reviewing the results of the 2019 weed study and consulting with experts, decided that EWM levels hadn’t reached a volume that warranted treatment. One of the challenges in deciding when to treat a lake (or not) is balancing people’s enjoyment of the lake with the risks of overtreating it which can result in herbicide treatments being less effective in the future. (This is a similar concept to antibiotic overuse in humans and animals). 

Avoiding (Potential) Double Treatment

Responsible herbicide application also includes individual property owners not treating their own shorelines with herbicides if the same shoreline has been identified as a treatment location in the CLIA’s EWM treatment plan.  That is, the same area being treated twice is discouraged.  

If the CLIA decides to treat EWM, additional information will be emailed to members and posted to the CLIA’s website.   

Other Lake Treatments

Please note that this potential EWM treatment is separate from other initiatives on Crystal Lake, including:

  • the CLIA’s algaecide treatments (lake association members were mailed a permit application in January 2020),
  • the City of Burnsville’s curlyleaf pondweed harvesting (another aquatic invasive species and lake association members were mailed a letter around April 2020), and
  • private companies’ treatment services for individual property owners.