Minnehaha Watershed District: Zebra Mussels Improve Water Clarity in Lake Minnetonka

Zebra mussels have caused significant changes in Lake Minnetonka’s water quality, according to findings of a study by Minnehaha Creek Watershed District (MCWD). The District has been monitoring the lake’s zebra mussel population since they were first detected there in 2010. Five years into the study, which was developed in partnership with Blue Water Science, MCWD released its findings on Thursdsay, April 21 at its AIS Spotlight, a gathering of community leaders at Minnetonka Community Center.

The District has discovered the biggest water quality changes are occurring among bays with the highest number of zebra mussels. In Wayzata Bay, which the population topped out at an estimated 200,000 zebra mussels per square meter in 2014, there has been an increase in water clarity and a decrease in algae (Chlorophyll) and Phosphorus. Those changes are not as prevalent in bays with lower zebra mussel populations. In Halsted Bay, which has 28 zebra mussels per square meter, there has been little change in water clarity, Chlorophyll and Phosphorus.

One suspects that some bays with improved water clarity may see an increase in aquatic plant habitat.