Bay Treatment Program Update
2026 Spring and summer treatments for all bays enrolled in the Bay Treatment Program are complete.
Fall treatments for North Arm Bay will begin in late October depending on water temperature. It has been a warm fall, but temperatures should be cool enough for treatment to begin within the next couple of weeks. All permits are in place, so as soon as conditions are right, the treatments will be started.
The treatment will be done using an low-dose herbicide. This will avoid any risk to native plants or animals and no restrictions on water use or swimming are required. Low-dosage treatments require cool water to keep the herbicide in solution long enough to effectively target Eurasian water milfoil. Following the first treatment, a second treatment will be completed sometime before ice-on, likely in late November. This should be sufficient, but if needed, a third treatment through the ice or shortly after ice-off next spring will be done.
Nature is unpredictable, but current conditions are pointing toward a mild winter with relatively little snowfall. This typically leads to rapid weed growth in the spring. The good news is that late fall treatments have proven to be very effective, so patience this year should result in excellent control of Eurasian water milfoil next year and for several years to come.
Bay Treatment Program
Over 15 years of data collection and review by independent aquatic plant experts and the Minnesota Department of Natural Resources (MnDNR) show that the Lake Minnetonka Association’s Bay Treatment Program has met or exceeded its program expectations and that native plant diversity is rebounding. Further studies show the Lake Minnetonka Association’s Bay Treatment Program is the safest, most cost effective way to control non-native, invasive weeds.
Several bays participate in the Eurasian watermilfoil and curlyleaf pondweed Bay Treatment Program. The Lake Minnetonka Association currently oversees invasive weed treatments on: Browns Bay, Carsons Bay, Crystal Bay, Gideons Bay, Grays Bay, North Arm Bay, Phelps Bay, Smithtown Bay, and St. Louis Bay.
Treatments on St. Albans, Stubbs, and Carmans Bays are managed by lake improvement districts created by lakeshore residents to pay for the invasive weed treatments. Beginning in 2026, The Lake Minnetonka Association will no longer accept donations for the control of invasive weeds in Stubbs Bay; however, it will accept donations and serve as fiscal agent for the Stubbs Bay phosphorous reduction program.
Bay treatments on Lake Minnetonka are successful because they are built on a foundation of good science, thoughtful project management, broad public support, and a strong partnership with researchers, aquatic plant experts, and the MnDNR. The success of this program is principally due to the work of our Bay Captains and the financial support of bay residents, businesses, and communities. Thanks to them and their efforts, a large part of Lake Minnetonka has been returned for boating and swimming and the ecological health of the lake is improving. Each person or organization who contributes their time or resources to this effort, are helping to restore the ecology and protect the legacy of beautiful Lake Minnetonka.
For information on how to enroll your bay in the Bay Treatment Program contact the Lake Minnetonka Association.