My experience has been that the Pink Sensations & Red Attractions and some yellows stayed well behaved. But an aggressive whites I got out of a lake have grown out about 30 feet from the shore line and have spread all around my pond and I would guess they are growing in about 5 feet deep water. But that is what I want. I have never tried it but I would think lilies would be easy to kill back by just spraying the leaf tops. Amine 4 2,4-D is listed as usable in water for aquatic weeds and is very cheap.

John