The West desert here in Utah is the home of the Onaqui wild horse herd. About a 2 hour drive from Salt Lake City, or my home, Provo.
"Onaqui" is derived from the from the Native American language of the Paiute tribe, who are indigenous to the region where the wild horse herd resides. "Onaqui" is believed to mean "the place where the rocks come together", a reference to the rugged landscape where the horses roam. It is open country where there are many places that you can go and see nothing man made except the dirt road your driving on.
During the mid-1800 the Pony Express traversed the area that the Onaqui herd roams. The pony express route went between St. Joseph, Missouri, and Sacramento, California, a distance of about 1900 miles. The stations were about 10-15 miles apart and a rider would gallop from one the the next where he would get a fresh horse. Each rider would cover about 100 miles per day. It would take about 10 days to travel the route. There are several historical sites/markers and the main (dirt) road through this area is called the pony express route.
Random thoughts:
This road can be hard on tires. It is remote, often without cell phone coverage (although that seems to be improving). Be prepared with what you need to get out of trouble. Before I upgraded the tires on my truck, I had two flats in one trip.
There is nothing out here. You can't get gas, food, .... If you get in real trouble, its a about a 10 mile drive to dugway military base. It's about 50 miles to Tooele. The closest accessible gas and/or hotel.
Weekends get busy. If you want a herd to yourself, sunrise during the week is better.
As with all nature photography, patience is key. Nothing will happen for an hour or two, then you get a chain reaction of stallions fighting. Or, multiple horses deciding its time for their dust bath. Or, whatever other horse activity of interest crops up.
There is a 100 foot rule on approaching these herds. You will see this rule broken regularly. Mostly, these herds are habituated to humans. But, getting close can be dangerous. Fights break out frequently and next thing you know, you have stallions galloping strait at you. So, a telephoto is your friend. Remotes also work great if you are willing to risk your camera. The horses are curious and will come check out any unattended gear. We have some great shots of horse nostrils. My wife had a horse decide that it wanted to scratch its butt on her tripod/camera. After nocking over the camera, it decided it was not done. It sat on the tripod and continued scratching. Fortunately the camera was ok, but, the tripod will never be the same.
The only times I have had issues finding the horses is in the wet spring when they are not constrained to be near one of the watering holes. Binoculars are almost always needed. At a mile away, a bush can look like a horse and a horse can look like a bush.
Many of the side roads, mostly those going into the hills, are best traveled in a high clearance vehicle.
The ground is covered in prickly poky stuff. If you plan to kneel or lie down to get a good angle on the horses. Wear long tough pants.
There are a lot of pronghorn out here. Another photographic subject. They can be a bit skittish.
As always, check the weather. its a desert and blue skies are the norm. Some nice clouds can really spruce up a background and hopefully get you a nice sunset.
Its all BLM land. There is a campground at Simpson spring, but I, and almost everyone else, find a nice pullout on a side road and camp there.
The Onaqui Catalogue Foundation puts out a herd catalog that has pictures, names and other info on each horse. I download the catalog, a pdf, so that I can have it out there with me and identify the various horses: https://onaquicatalogue.org