Wow I've seen those signs on farms in areas that have ponds or good size creeks running through them there's outrageous buffer zones to keep farmers form planting or spraying around them ....funny part is the farmer gives them permission to create the zone and are compensated for some of the loss they even have some places you cant even walk on let alone use for farming ..
The EPA uses extorsion to elicit "permission" from the small farmer. He cannot begin to challenge the forces of the feral government. Some have tried, that's why they're gone.
For a good look at the "zones", you really need to take a low level aircraft flight across our fruited plains and see the boundaries set up around "drainage ditches" also known as gullies. The EPA is an out-of-control government bureaucracy that cannot be challenged in a court of law. It is used to the benefit of the large corporate entities that wish to take control of the production of our food.
What the farmer has done is rotate property taxes forward to any future owner when it comes to his marginal land.
We were checking out land in Bartholomew County, Indiana. We discovered that ANY piece of land on a 1 degree or greater slope was part of a Conservation District and didn't pay property taxes.
There's some lawyer in Columbus who can churn the easements out like crazy, and has done so.