Don't underestimate manual removal. Manual removal can do wonders for a small pond (1 acre). No cost other than your labor. It opens things up for the fish/fishing. But best of all it removes the nutrients from the pond (they are bound up in the removed weeds). Not so for other options as they are recycled (unless you remove the carp or tilapia or fish).
The pond is question is 15 acres. The last time I tried to remove unwanted vegetation from 15 acres it was cockleburs in a soybean field and I was 12 years old.
