I'm surprised the DUmmies haven't suggested a more "organic" and "natural" solution. I purchased some beautiful ducks and geese who spend a good part of each day munching on this grass and other creek side nuisance plants. Once they're a few months old they waddle down to the pond/creek (mine wander back and forth during the day) and dine on grasses, snails, and whatever else they eat down there. The bonus, of course, is the Christmas goose is available on site.
Cindie