It has long been known that most of the nutrient pollution in the Chesapeake Bay comes from agriculture operations in Pennsylvania.  Here is a short video report on the 2018 State of the Bay.  

The State of the Bay is an Annual report from the Chesapeake Bay Foundation that reviews the overall health, and the recovery efforts.  The notes on Pennsylvania begin at 1:29 in the video.  

https://www.youtube.com/watch?v=ZcUQmITvsRo&t=86s

This area is part of the Chesapeake Bay Watershed, and we need to do our part to help the Bay's recovery efforts.  The fields where this material is being spread, feed into the Conodoguinit and Yellow Breeches Creeks; which feed into the Susquehanna River and ultimately the Chesapeake Bay.