Thanks FishinRod
Yes , many years we have enough flow through that a marsh has developed downstream from the outlet. I've built a couple of small "frog ponds" below the overflow with my tractor, too.
Removing the grass carp would be as simple as shooting them as they cruise by eating Endurance. Also, I could string up one of my salt water fishing outfits, chum them for a bit with bread , and have the fight of my life. I bet such a tussle would muddy the waters. If not a "bigger boat", I'd certainly need a much bigger landing net.