My experiences have been the same as esshup described. I understand the desire not to use chemicals, but selective aquatic plant control can be a bear if done manually. Chemicals like Rodeo and Navigate have been thoroughly tested, and work well if applied correctly. It does take a little longer to see results than with a contact herbicide, but the results seem to me to be more permanent.
I don't know what kind of lilly pads you have, but if they get seed heads like American Lotus does, I'd make sure the flowers are treated/removed before they have a chance to drop more seeds.
I would also remove all the cuttings whether you chemically treat or not. Decaying plant matter is not something you want in your pond.
Good luck, whatever method you use.
