Recently, the Chesapeake Bay Commission released a report Healthy Livestock, Healthy Streams to advocate for stream fencing, one of several dozen longstanding agricultural best management practices (BMPs) recognized by the Chesapeake Bay Program.  Promoting stream fencing is common sense: when livestock loiter near streams, they compact soil, clearing a path for runoff; when they enter the stream, they erode its bank and send sediment into the channel; and when nature calls, they deposit “nutrients” directly into the stream.  It is not just bad for aquatic habitats, it is bad for farmers and their vet bills. 

Despite significant reductions over the past 30 years in nutrient and sediment loading from agricultural sources, the share of these pollutants from the agriculture sector has remained remarkably consistent, contributing, for example, 45% of the nitrogen to the watershed in both 1985 and 2014.  However, the Bay TMDL calls for the agriculture sector to bring this down to about 40% of the total load, requiring the sector to shoulder over 60% of the reduction burden (figures are even higher for phosphorus).  The good news is that reductions from the agriculture sector are widely recognized to be the most cost effective, although, as noted below, there …