One reason is to preserve the water resources in the area. The cattle have pretty thoroughly trashed the springs on her property, turning them into essentially mud wallows. Most of the private property in the area is fenced off, and this property was previously. But fence doesn't last long without maintenance in a wooded area, and the fence here hasn't had any upkeep for a long time - in many places, there's no fence left at all.

There are also financial reasons - the going rate for grazing on private land in Idaho is something like $15 per head per month. Right now we're getting zero per head per month. We do plan on going around and meeting the neighbors, but will likely end up building a fence. If they're paying for grazing rights on the property, the ranchers are going to want a fence there too.