The agricultural landscape has four major sources of nonpoint source (NPS) pollutants. These are: 1) surface and subsurface runoff which carry sediment and agricultural chemicals to streams; 2) eroding streambanks which can contribute more than fifty percent of the sediment load to the stream; 3) field tile drains which contribute the highest concentrations of soluble agricultural chemicals to streams; and 4) livestock grazing of streamside or riparian areas which contribute to bank instability and add animal waste and pathogens to the water.
Schultz, Richard C.; Isenhart, Thomas M.; and Colletti, Joe P.
"Agroforestry Systems: The Bear Creek Riparian Management Success Story,"
Ames Forester: Vol. 84
, Article 2.
Available at: https://lib.dr.iastate.edu/amesforester/vol84/iss1/2