Check with you local farm service or conservation people. If your
pond is hospitable to the lilies, I can't see what would stop them
from choking it out. Have you any triploid grass carp in the pond?
Where are you located?

We have an acre pond, also with bass and bluegill (and red ear) in
MS. The agents recommend not putting greenery in it. Our grass carp
are taking care of that!

Jim