The pond is next to a hay pasture. The pasture is around 80 acres but only about 15-20 acres would have drained towards the general direction of the pond. I lease the pasture out to a hay farmers and it is very likely that he applied fertilizer prior to the big rain. If he did and if I ended up with a lot of fertilizer in my pond, would that explain the off colored water? Does that mean that I have an oxygen depletion? Would that cause the pond water to "flip?

Another change in the pond is that I have alligator weed around the entire perimeter of the pond. I never had any in the pond before and now it is everywhere. Seems unlikely that the flood occurred and then 2 weeks later I have all this alligator weed but it sure seems strange to me that I went from none to a lot in just one year.