Figure showing total phosphorus (TP) tributary loading to Lake St. Clair and the western Lake Erie in 2018 in metric tons per annum (MTA). Runoff from agricultural areas is the major source of nutrient loadings with about 70 percent from commercial fertilizer application and 30 percent from animal manure. Diagram and map by Michigan Sea Grant, M. Maccoux, Contractor ECCC, S. Wortman, USEPA, D. Obenour, NCSU, M. Evans, USGS/IJC.
