In graduate school I studied the effects of land use practices on the concentration and distribution of Giardia lamblia and Cryptosporidium parvum and fecal coliform bacteria. There were statistically significant higher concentrations of both the bacteria and protozoans in watersheds where dairy farming took place when compared to protected watersheds (pristine forest where humans were not allowed) and watersheds with suburban developments.
Every visit to this miserable place is support for the cattle industry and the resulting environmental consequences, including cowshit in your water. We eat way too much beef in this country. WAY too much.