I have been observing horses feeding _IN the portneuf river a lot in the last two weeks. They walk right up and down in the river and rip up moss in the shallow parts and grass and cover from the banks and small islands. I think they do this because the field they are locked in is pretty much eaten down and there is little feed. I have called the owner and he has not ever called me back.
There is no Idaho statute that prohibits the described activity. This is not within IDFG’s jurisdiction.
If there is a concern about the horses' health or trespass by the livestock, then you should contact the county sheriff’s office.