By admin 
A long-awaited study of how an 8-foot-tall fence around a billionaire’s San Luis Valley ranch affects local wildlife has stirred further controversy in one of Colorado’s all-time land battles.
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The fence, a wire grid with barbs at the top and bottom, is potentially detrimental not only to the federally listed Canada lynx and silverspot butterfly, but could harm a whole host of species from the northern leopard frog, to eagles and hawks, to cutthroat trout, to deer and elk, the study found.
The 83-page report, a joint study by wildlife experts hired by the owner of the 83,000-acre Cielo Vista Ranch and the Costilla County commissioners, recommends a significant list of modifications to lessen the impact on wildlife. Those include adding openings and jumps for large and small animals, raising the bottom of the fence 16 inches off the ground, enlarging the wire-grid squares to at least a foot from the current 3.5 and 5.5 inches, and removing the barbed wire from the top and bottom.
A 5-foot fence would suffice, the study found, to contain the ranch’s bison herd.
Costilla County residents who have been battling the fence for years are again calling on the ranch owner, William Harrison, to tear down the fence or at least complete the recommended changes.
Harrison’s attorneys did not respond to requests for comment from The Colorado Sun this week. But his legal team informed the county that “there would be no negotiations involving the contents of the report,” county officials told The Sun.
The county received the report, part of a court-ordered mediation over the fence, last fall. It was kept confidential until Costilla County commissioners recently released it to the public, exposing the stalemate on its recommendations. The report began in June 2025.
A group of local citizens who call themselves the La Sierra Environmental Guardian Committee said the wildlife report is even more evidence against the “silly” idea of “an 8-foot-tall fence encircling an empty vast wilderness.” The group calls the land contained in the ranch La Sierra, part of the Sangre de Cristo Land Grant of 1844, which guarantees the heirs of the grantees access to the mountain to gather firewood and graze livestock even while it has been owned by Harrison and previous ranch owners.
“We don’t understand why he refuses to do the obvious right thing. His claims that an 8-foot-tall fence is necessary to contain his small bison herd are now debunked by the wildlife biologists,” the La Sierra Environmental Guardian Committee wrote in an email.
“We believe the main reason he doesn’t want to follow the wildlife report’s recommendation is because it is much more critical of his fence than he expected. He seems to not be willing to admit that the community was right all along about his ill-conceived fence project. Unfortunately, the damage is done and the community and the environment must now suffer.”
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The battle over the fence has dragged on for several years. Construction, including a bulldozed path through piñon trees and sagebrush, began in 2020. It was halted in 2023, after about 20 miles of fence line were erected, when Costilla County commissioners won a temporary injunction against Harrison, who purchased the ranch in 2017. The matter is still tied up in court.
The La Sierra committee said the report recommends 356 specific modifications to the fence, including removing more than 3 miles of fence line and creating 132 openings for wildlife to cross. It recommends 176 jumps for large animals, along with smaller openings for elk calves and deer fawns to pass.
It also suggests “high-visibility” wires or markers on the top and middle of the fence so that big game and birds see the wire.
The full list of species that have been impacted or could potentially be affected by the fence contains more than 30 kinds of game, birds and other species:
Northern leopard frog, American marten, Gunnison’s prairie dog, little brown bat, northern pocket gopher, snowshoe hare, southern red-backed vole, white-tailed jackrabbit, bald eagle, band-tailed pigeon, black rosy-finch, boreal owl, Brewer’s sparrow, brown-capped rosy-finch, burrowing owl, flammulated owl, golden eagle, greater sandhill crane, juniper titmouse, lazuli bunting, Lewis’s woodpecker, northern harrier, olive-sided flycatcher, pinyon jay, prairie falcon, rufous hummingbird, short-eared owl, Swainson’s hawk, Virginia’s warbler, Rio Grande cutthroat trout, elk, mule deer, Canada lynx and silverspot butterfly.
Nearly all the species listed in the report have “significant wildlife habitat” within a half-mile of the fence line, it said. The fence lines also overlap with an elk migration corridor used to access streams and habitat, according to Colorado Parks and Wildlife.
As part of the meditation, the ranch and the county each hired their own wildlife experts to collaborate on the study. The ranch hired ERO Resources Corporation, and the county hired Patricia Cramer of the Wildlife Connectivity Institute.
“There are highly important areas for a diversity of species of wildlife where it is recommended the (Cielo Vista Ranch) fence be removed,” the report says, mentioning fence line near El Poso Creek and Vallejos Creek.
In November, state officials said construction of the fence violated water quality laws meant to protect against erosion and disrupted water flow. In a cease-and-desist order, the Colorado Department of Public Health and Environment said the disruption of the soil could send sediment down the mountains and into arroyos, creeks and the Rio Grande River.
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