Agriculture, while not the only source of non-point pollution in East Central Wisconsin, is the largest source.  A Total Maximum Daily Load (TMDL) study was conducted by the Wisconsin Department of Natural Resources (WI DNR) in the Upper Fox and Wolf Basin to understand sources of total phosphorus and total suspended solids in the Upper Fox-Wolf Basin. 

The study measured total loading from the two prominent river basins; the Upper Fox River (including Lake Winnebago), and the Wolf River.  The two pie charts below show the main sources of phosphorus and suspended solids revealed by the study.  

Further details about non-point sources of pollution in the Upper Fox-Wolf basins can be found in the Wisconsin Department of Natural Resources’ Total Maximum Daily Loads study.