The Zebra Mussel (Dreissena polymorpha) has had an effect on Lake Winnebago, especially where there are plenty of rocks for them to attach to, but just how much it is difficult to say. Zebra mussels pull algae and zooplankton from the water column, clearing the water to some extent. They deposit their waste on the lake floor obviously, this changes where nutrients are in the lake. What all this does has actually done to Winnebago is unknown, but it has drastically changed Lake Michigan. The windrows of zebra mussel shells in this photo are located at Wayside Park on the Southwest shore of the lake.