I need help/ advice please.

Pond is about 3/4 acre and is 4 years old. Fed by runoff during heavy rain events. Bottom diffuser aeration that has been running 24/7 since late spring. I went through the proper startup procedure. Pond is stocked with LMB, HBG, BG, YP, and 25 CC.

I think I made a catastrophic mistake about 2 months ago. I had a field tile blowout and made the mistake of straight piping it into the pond. About 3 weeks ago the water turned a blue/ green color with a oil slick looking substance on the pond. I woke up yesterday to 60 or so dead fish that ranged from the biggest LMB and CC that are in the pond to fingerlings.

The algae substance is not visiable currently and I have removed the direct piping of the field tile. I guess my question is do you think that now I believe I have contaminated my pond is this going to be a continued problem?

I'm sure I'm forgeting some important details but I'm pretty upset with what has happened.

Thanks Kenny