Virginia Range mustangs at Hidden Valley Regional Park, east of Reno, NV. The fence was probably installed by volunteers, to keep the horses away from populated areas and hazards related thereto.
Unfortunately, it may impair their ability to find water so the other part of the equation is to provide water where you want them to roam, a concept known as ‘diversionary watering.’ Keeping them wild and up in the hills is a good thing.
H/T Dr. Jennifer Jewell, PhD.
Western Horse Watchers Association 