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Wild Horses: Adored by the Public, but Destroying Water Resources

New research from California’s Modoc National Forest shows an exploding population of wild horses is devastating natural springs that are vital to wildlife and public uses. And there’s no clear solution in sight.

Written by Matt Weiser Published on Read time Approx. 7 minutes
Field capture image of wild horses at spring
A herd of wild horses at a spring on the Devil’s Garden Plateau in Modoc National Forest, California.Laura Snell

Wild horses are deeply ingrained in the mythology of the American West. They represent a spirit of freedom that has long defined the nation.

But wild horses also pose a thorny management problem. A federal law passed in 1971 restricts what the government can do with the horses, even once they begin to affect the environment.

The United States Bureau of Land Management and the U.S. Forest Service periodically conduct roundups (“gathers”) to thin the wild horse herds. Sometimes the animals are given birth-control drugs and returned to the range; sometimes they are corralled until they can be adopted by private citizens. Both strategies are expensive.

Periodic scandals concerning illicit slaughter of wild horses for profit have made land managers reluctant to consider bold actions, such as euthanasia or even a simpler adoption process, as reported by Slate and National Geographic. This has also created a strong distaste among the American public for aggressive management.

Large concentrations of wild horses can degrade wildlife habitats as well as the grazing land leased by livestock operators, changing plant communities and causing serious soil erosion problems. The animals also degrade fragile wetlands and water supplies, although research into these effects is limited.

Now new research on the Modoc National Forest in remote northeastern California shows that growing numbers of wild horses are devastating remote springs that are often the only water supply available to wildlife.

Laura Snell, a livestock and natural resource advisor with the University of California Agricultural and Natural Resources Service, has found that wild horses dominate the spring sites, harming water quality and even sometimes halting water output. Water Deeply recently interviewed Snell about her research.

Water Deeply: What’s the situation with the wild horses in Modoc County?

Laura Snell: We have the largest Forest Service-managed wild horse herd in the country. There are two wild horse territories there. Between those two territories, there should be somewhere between 200 and 400 horses, and there are currently over 3,000. Horses are pretty much taking over the rangeland on the Devil’s Garden Plateau.

As a result, we’re seeing a major shift from our native perennial grasses to annual grasses, which is not only decreasing the quality of grass and habitat, but it’s also increasing wildfire risk.

We’re also seeing that wild horses will select these natural spring sites over stock pond water. There’s plenty of water out on the garden for livestock and wildlife. But the wild horses select these spring sites and they will just stay on those spring sites all year round. And we’re seeing pretty major effects of everything being eaten around these spring sites until the point of bare ground – sometimes bare ground that extends like 30–50ft from the edge of the water.

We’re also seeing water quality issues. Wild horses do like to eat aquatic vegetation, as well. So when they have eaten all the grasses and things around, they will also eat all the aquatic vegetation that’s in the spring, as well. So we are then seeing pretty big decreases in our macroinvertebrates, and the species that are able to exist in these springs. So you’re going from places where you used to have mayflies and caddis flies, and places that used to be able to support ducks and birds, to where we now have snails and leeches and fly larvae.

Water Deeply: Why has the population of wild horses exploded?

Snell: Until last year, they had not conducted a wild horse gather for 10 years. The reason is the BLM (Bureau of Land Management) and Forest Service stopped working together to manage horses. Eleven or 12 years ago, there were some issues in D.C. where the Forest Service didn’t pay a bill to the BLM, and the BLM said we’re done dealing with you. So this herd just continued to grow and grow, doubling every four or five years to where it is now.

Water Deeply: Are these water-related impacts from wild horses common around the West?

Laura Snell (right) and U.S. Forest Service colleague Jenny Jayo install wildlife monitoring cameras to document wild horse activity at a spring in the Modoc National Forest. (Will Suckow)

Snell: Yes, I believe so. My study is in Modoc County, and there is another adviser in my position in Lassen County, and he is doing a paired study in eastern Lassen County and western Washoe County (Nevada). They’re very similar in terms of natural spring conditions. You see not only the vegetation degradation, but the trail cameras also show just the amount of time that wild horses are spending at these spring locations.

We’re also getting photographic evidence of intimidation. When horses are at a spring, they are intimidating elk, deer, cattle and pretty much everything else. They will aggressively push them out.

Water Deeply: Are wild horses affecting water supply around these springs, also?

Snell: They can. We have areas where the springs are in mostly clay-based soils. And at those springs that are in more muddy-bottom areas, horses can actually create a stopper to the spring and actually either move that spring site back or they’re actually clogging the spring with their hoof action.

We have pictures of 80 horses standing in a spring at one time. When you get that many horses in a spring like that, we do have cases where horses have actually stopped the spring. When you get a lot of constant pressure on them, it can definitely stop the spring.

Water Deeply: How important are these springs?

Snell: These springs are really important. These areas are mostly sage-steppe and juniper woodland, and a little bit of pine woodland. These springs are like the only natural sources of cold water. So all these species have been using these springs, from aquatic insects up to waterfowl traveling the Pacific Flyway. We have a lot of waterfowl species that use these areas to rear young. Good quality spring water is pretty essential to make vegetation to nest in and to make bugs for those little ducks and chicks to eat.

Water-wise, the cattle can still go to stock ponds. But these special riparian areas, most of them have been fenced out for livestock for about 50 years. And now the horses have broken through fences and they’re sitting on these areas.

It’s a sad sight out there. There are only, like, 30 of these sites in about half a million acres. They’re pretty important. When you move into Washoe County, it’s the same thing. Washoe gets into a lot drier sage-steppe. So those watering areas are just essential to all life out there.

Water Deeply: And do these damaged springs affect water supply downstream?

A fence line comparison of impacts from wild horse grazing at a spring in the Modoc National Forest. To the left of the fence wild horses roam freely on U.S. Forest Service land. On the right is private land with managed livestock grazing. (Laura Snell)

Snell: Some of them do, but most of these don’t. The volcanic nature of this area, it’s like you get the spring for a while, then the spring kinda goes back into the volcanic rock. So they go anywhere from a few hundred feet to some that will go a half-mile or a mile into a reservoir or something.

They’re not super long. That’s partially why they get so damaged, too. It’s a very concentrated use by these large numbers of animals.

They do contribute to recreation use. Big Sage Reservoir is a large recreational use. A lot of them also contribute to smaller reservoirs and streams that are used for fishing. There’s quite a bit of fishing that happens on the Modoc National Forest.

Water Deeply: Are wild horses native to North America?

Snell: Of all the research I have read, wild horses are not native to North America in the species that they currently are. Not only that, the wild horses that exist in the Modoc National Forest are all domestic horses that were turned out when farming was mechanized – the 1920s and 1930s.

The Native Americans that live in this area do not have horses in their natural history. They’re all supportive of management of wild horses. The gather that was done last year was all on private and tribal lands. Quite a few of these spring areas are really important cultural areas for the Modoc and Pit River tribes, so they’re not really happy about the horses.

Water Deeply: What do you think is the right management solution?

Snell: Some groups say the horses are wild, and we need to treat them like wildlife. Well, we have hunting seasons for wildlife. But we’re not allowed to treat them like that.

We also don’t treat them like livestock. I really think sale of horses should be allowed. I think if there are groups that want to buy those horses and keep them, that should be fine. If there’s a group that would like to eat those horses, I think that’s fine.

We need to stop having our hands tied. That’s my opinion. We manage everything else. Why aren’t we managing horses? I truly believe, if there’s a group out there that wants to buy or adopt those horses, like dogs and cats, they should be able to.

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