No experience with lake mower. If you want some areas rid of the lillies and parrot's feather the 2,4-d granular is the way to go. Applicaitons rate is max rae 200 lbs/acre. Might take 2 applicaitons to rid of watersheild if you have that. So it is pricey. Call me if you like and I can see about prices. The liquid 2,4-d does nto work for us on lilies I do like to mix in a cocktail with glyphosate. 3% glyphosate and 2% 2,4-d liquid and 1 ozs surfactant. This is much cheaper than 2,4-d granular (navigate) but does not seem to do as well for longterm control. For a 100 acre lake you cna treat up to 20 acres of pads at once so don't think you are going to go that high anyway so your fine.