I fish the Spring so this topic concerns me. Seems to me the source needs to be investigated so it can be properly addressed rather than just pointing fingers at possible ghosts.
Ecoli being a product of large mammal feces could come from a lot of sources other than people or cattle operations. It seems to me that it could come from horses, deer, geese raccoons, possums or a or possibly a combination of all the above. What about Beaver? There are getting to be more and more of them around.
Seems to me finding the actual source rather than just pointing fingers would be a good plan.