Zebra mussels were discovered by a local resident on July 27, 2010,  and confirmed by DNR biologists on July 28, 2010. DNR, Minnehaha Creek Watershed District field staff and Lake association staff conducted an extensive shoreline survey on Lake Minnetonka in the week following the discovery, and confirmed the presence of young (less than one year old) zebra mussels at 10 of 48 sites checked on the lake (See map).

The widespread distribution of young zebra mussels indicates that there is a breeding population (size unknown) that has been in the lake for at least one year. Zebra mussels are present in Grays Bay, Wayzata Bay, Robinson's Bay, St. Louis Bay, the Lower Lake North portion of Lake Minnetonka, including the portions of Big Island. Zebra mussels have also been detected in Minnehaha creek just below dam at the outlet of Lake Minnetonka. No zebra mussels have been detected in the upper basin of the lake (portions of the lake west of the Arcola bridge and the Narrows bridge which leads old channel bay). More surveys are planned as the summer progresses.

MCWD and MN DNR sent out a zebra mussel mailer to all Lake Minnetonka residents on September 24, 2010.  The mailer asked for residents to participate in MN DNR's zebra mussel monitoring program. As residents removed their boats, jet skis, water toys, docks, boat lifts, and water pumps for the winter, the residents were asked to check for zebra mussels and report findings to the DNR. The mailer included basic information on zebra mussels, what a lakeshore boat owner could do, as well as the volunteer zebra mussel monitoring report form. MCWD also asked the marinas and boat lift/dock companies to be actively checking recreational vessels and equipment for zebra mussles as they removed them from the lake and to report the results. The map below shows the zebra mussel sightings confirmed from the DNR (earlier in the summer) as well as the monitoring reports from Lake Minnetonka residents, marinas, and boat lift/dock companies.