Eurasian watermilfoil (EWM) is an invasive species, native to Europe, Asia and North Africa, that has spread throughout the Midwest. EWM can create dense stands and dominate submergent communities, reducing important natural habitat for fish and other wildlife, and impeding recreational activities such as swimming, fishing, and boating.
EWM is typically at its peak growth stage during the latter part of the summer. Each year, the EWM population would be mapped during the late summer. These data can be seen in the 8-page EWM map book posted here, or in the Interactive Web Application: link to MKLPA Page.
Hybrid water milfoil (HWM) is a cross between the native northern water milfoil and the invasive EWM. In general, HWM has thicker stems, is a prolific flowerer, and grows much faster than pure-strain EWM. These conditions may likely contribute to this plant being less susceptible to being controlled by standard use rates of certain herbicides. HWM tends to interfere with recreation, navigation, and aesthetics more than pure-strain EWM populations. EWM and HWM have been confirmed from the Minocqua-Kawaguesaga system, with the MKLPA currently conducting research to learn more about the genetic composition of the invasive watermilfoil of the system.
EWM was first documented from Minocqua Lake in 2001. The term Best Management Practice (BMP) is often used in environmental management fields to represent the management option that is currently supported by that latest science and policy. The MKLPA has implemented BMPs over the years, including herbicide spot treatments, weevil introductions, and manual removal efforts.
Staring during the late-summer of 2019, the MKLPA contracted with Onterra, LLC to conduct EWM monitoring activities and provide technical guidance and direction on EWM management moving forward.
Management activities are carried out by third-party contractors selected by the MKLPA. In 2020, the MKLPA’s management strategy included herbicide treatment, carried out by Schmidt’s Aquatic, LLC and manual removal, conducted by APM, LLC .
EWM Monitoring & Management Planning
Since 2005, Onterra, LLC has been offering objective, science-based lake management planning services throughout the state of Wisconsin. Onterra works with the MKLPA to develop realistic and effective EWM management programs, along with designing and implementing the appropriate monitoring strategies to evaluate the efficacy and selectivity of the management action.
Each year, Onterra will be conducting a number of field surveys to assess ongoing management activities and be used to guide future strategies. Based on the survey results, Onterra ecologists/planners will meet with MKLPA representatives and other stakeholder groups to construct management plans for the following year. An annual report will be constructed each year that will present the data collected and outline the preliminary plan for the following year
The October 2019 Strategic Planning Committee Meeting presentation materials and the 2019 EWM Monitoring & 2020 Control Strategy Development Report outline the 2019 strategy and the stakeholder participation that occurred.
In 2019 and 2020, the MKLPA has contracted with Schmidt’s Aquatic, LLC to conduct herbicide treatments spatially targeting EWM. Herbicide treatments were conducted with ProcellaCOR EC, specifically designed for short exposure time spot treatments of invasive watermilfoils.
In 2020, the MKLPA has contracted with Aquatic Plant Management, LLC to conduct manual removal of EWM. Some areas would be targeted with traditional hand-harvesting techniques and others would be targeted with the assistance of Diver-Assisted Suction Harvest (DASH). DASH involves divers removing plants and feeding them into a suction hose for delivery to the deck of the harvesting vessel. The DASH methodology is considered a form of mechanical harvesting and thus requires a WDNR approved permit.