When any forest trees are situated upon the bank of any watercourse or so close thereto as to be in danger of falling into it, the owner or occupant of any of the premises shall be notified to remove them forthwith. The notice shall be based upon a resolution or order of the county commissioners and may be given by mail to the last known address of the owner or occupant. If the trees are not removed within ten days after the date of the notice, the county may thereupon fell them.