Yeah, I saw similar numbers from EPA docs when I decided I might want to back up my comment, thanks :) but what I'd like to know is what the median size of a dairy farm in the US is, and what proportion of the milk we drink comes from larger operations like those described here, with head counts of 15-20,000: http://en.wikipedia.org/wiki/Dairy_farming#Animal_waste_from...

(Of course I know Wikipedia isn't the most reliable and those specifics seem to be lacking citations)