Thanks for the ideas...

Our ponds have an 18' saftey shelf (as required by code) and taper
down to 6' at the deepest point in the middle. So the cattails had
plenty of room to grow.

Another idea was to put stone around the banks of the ponds, but I'm
sure that would not be cheap.

Chip, we're neighbor's - I'm in Racine county, just North of you..