I hate to say it, fellers, but farms are point sites for industrial waste and they have largely gotten a "pass" on compliance with pollution laws. I am in a farming family and I know what kind of pollution and runoff there is. There are few rivers and creeks in southern Minnesota farm country that aren't tainted to the point where fish should not be eaten from them. Most can only support rough fish. The most polluted river in the state, the Zumbro, is in the heart of farm country and is so polluted because of farm run-off. I'm talking corn and soybean farms, not livestock.
Current mainstream farming practice is based on the "better living through chemistry" paradigm of about 50 to 60 years ago: apply pesticides and chemical fertilizers as much as possible.
Ironically, a lot of today's "organic" farmers have discovered that all this chemistry is not necessary and that good results are gotten without it, or with limited application of it.