Invasive Species

There are currently two invasive aquatic plant species found in LCO, curly-leaf pondweed (Potamogeton crispus L.) and Eurasian watermilfoil (Myriophyllum spicatum L.). Both grow very rapidly in water with high nutrient concentrations.

Curly-leaf pondweed and Eurasian watermilfoil identification

Curly-Leaf Pondweed

A small curly-leaf pondweed (CLP) infestation was first discovered in LCO in July 2006. The infestation was located near the entrance of Musky Bay and encompassed a dense patch that was approximately 0.20 acre.

After 2006, CLP spread throughout LCO. The annual midsummer die‐off of curly-leaf pondweed (CLP) releases nutrients back into the water column, which trigger algal blooms and create turbid water conditions. In recent years CLP infestation has been brought under moderate control using herbicides, hand-pulling, and most recently, the Eco-Harvester.

Eurasian Watermilfoil

A small patch of Eurasian watermilfoil (Myriophyllum spicatum L.) was discovered in little LCO in 2015. Eurasian watermilfoil spreads very quickly and can form dense mats that crowd out native species. Eurasian watermilfoil has been described as "CLP on steroids".

Extreme vigilance is needed to control the spread of this invasive. It is unlikely that the Eco-Harvester can keep up with the infestation, and herbicides will be needed.

LCO Aquatic Plant Management Plan

The COLA aquatic plant committee developed its first LCO Aquatic Plant Management Plan in 2011. The Aquatic Plant Management Plan was updated in 2021and includes a strategy to effectively and efficiently reach specific goals. The goals include the following:

Goal 1) Control existing levels of aquatic invasive species (AIS) Curly-leaf pondweed and Eurasian watermilfoil.
Goal 2) Prevent the introduction and spread of aquatic invasive species.
Goal 3) Preserve the lakes’ diverse native plant communities.
Goal 4) Lake residents and users are made aware of the importance of native aquatic plants, the means to protect them, and the threat of aquatic invasive species.
Goal 5) Restoration and preservation of native shoreline vegetation
Goal 6) Waterfront residents will protect lake water quality and plant communities by minimizing runoff of pollutants from their lake property.

Lac Courte Oreilles Aquatic Invasive Species Lake Monitoring Training Manual

Lac Courte Oreilles & Little Lac Courte Oreilles 2019 Aquatic Plant Survey Report

As in past years, aquatic invasive species (AIS) of particular concern are curly-leaf pondweed and Eurasian watermilfoil on both Lac Courte Oreilles and Little Lac Courte Oreilles. In 2019, Wisconsin Lake & Pond Resource, LLC was contacted by COLA to provide an aquatic plant survey focusing on AIS for each lake. The complete report is available here.

REPORTS FROM <2019

Available here.

How can you help?

Please support COLA’s Clean Boat Initiative by routinely inspecting all of your watercraft for AIS. If you have the time, please join COLA’s AIS or Eco-Harvester work groups to help identify and remove AIS.