Serious Alligator weed problem in pond

We had some old stuff that looked like mustard green seeds that I used a few years ago to kill it all but I guess it didn't get the root system because it's all back.

We have fought this shite for 10 years. Spraying with 2-4D in the summer when it's established doesn't do much good. It kills 10' of it but when it's grown 15-20' out into the pond it doesn't help and I'm scared I'll kill all the fish.

Can I just use any regular glyphosate and spray a little at a time? Is there a specific chemical I can use that less toxic? Id like to kill it off before it takes over this spring or the water gets too warm and has less oxygen