On the national level, the Federal Clean Water Act regulates pollution flowing out of pipes, known as point source pollution. But contaminants flowing off of farm fields — non-point source pollution — are exempt from regulations. With little authority to compel farmers to adopt clean water practices, state and federal agencies rely on a voluntary approach. As a result, farming practices can be dramatically different from one field to the next.
Read more at http://www.mprnews.org/story/2016/05/17/water-buffalo-red-river-agriculture-erosion