I may try to use my small tractor as described to provide some emergency DO, thanks for the tip.
No, I haven't had a chance to report it to the DNR yet, but will. I'll keep you posted on what they say.
Yes, the black water areas smell bad. So an inversion seems likely, as sprkplug suggested. I guess the cooler rain water running in repeatedly cooled off the top layer enough to cause the bottom muck/anaerobic layer to invert, if I understand the process correctly.
