Omigod, you've got Iris pseudacorus,
which, BTW, is kinda illegal in Illinois. It is an invasive,
vicious plant pest. What kind of pond do you have? If it's
a natural or clay-bottomed pond, just get in there and rip
out the giant tubers that are that monster's root system.
Get them to dry land, then jump up and down on them until
you are sure that they are dead.
It will not be easy and they will fight
If your pond is a rubber liner pond,
their roots can't penetrate the rubber. Get in there and
rip 'em out.
Your fish will love it. Carp love mud
and tolerate turbid water just fine. Ripping out the plants
will stir up stuff from the bottom that they'll find delicious.
DO NOT USE HERBICIDES! You'll kill everything else in there,
and the iris will just laugh at you.