CHEYENNE, Wyo. (AP) -- A legal settlement between ranchers and the U.S. Bureau of Land Management would reduce wild horse numbers by about half on more than 4,300 square miles of sagebrush country in the Red Desert of southwest Wyoming.
Under the agreement, the BLM would allow no more than 1,050 wild horses in four herd areas, down from the current population of just under 2,000 horses in those areas north and south of Rock Springs. Many remaining horses would be sterilized or receive fertility control treatments so they don't reproduce.
Wild horse advocacy groups that intervened in the case objected, saying Thursday that the settlement threatened to "wipe out" wild horses in the area.
The BLM contends that the settlement will maintain wild horses in southwest Wyoming while meeting a requirement under the Wild and Free-Roaming Horses and Burros Act for the government to remove wild horses from private property when requested to do so.
"We feel like this serves the objectives of the wild horse and burros act by retaining wild horses on the public lands while reducing landowner conflicts where the wild horses stray onto private lands," BLM spokeswoman Beverly Gorny said Thursday. "That's really the key issue in that particular area."
U.S. District Judge Nancy Freudenthal in Cheyenne approved the settlement Wednesday. The settlement requires the BLM to round up horses to meet the new herd target numbers. Roundups will occur this year through 2015, or 2016 if the population objectives aren't met by then.
The settlement stems from a lawsuit filed in 2011 by the Rock Springs Grazing Association, a group of ranchers who run cattle on a vast area of southwest Wyoming known as the Checkerboard. The area is a mix of public and private land that dates to federal land grants for the Continental Railroad.
Not nearly enough fencing exists to keep wild horses off the Checkerboard's private tracts. The result, ranchers say, is that horses damage the range and compete with cattle for forage.
The problem can be especially bad where cattle and horses alike congregate at water sources.
The association alleged the BLM allowed wild horse numbers to reach at least 4,700, almost three times the maximum number the BLM previously had agreed to allow in the early 1980s.
The association's president, John Hay, of Rock Springs, declined to comment Thursday.
Wild horse advocacy groups -- the American Wild Horse Preservation Campaign, The Cloud Foundation, and the International Society for the Preservation of Wild Mustangs and Burros -- objected to the settlement.
"We are appalled that the court has put a seal of approval on the BLM's plan to destroy some of Wyoming's last remaining and most popular wild horse herds," Suzanne Roy, director of the American Wild Horse Preservation Campaign, said in a release.
Wild horse numbers will be reduced in four herd areas as follows:
--The Salt Wells herd area south of Rock Springs, which currently has 686 horses and is supposed to have been managed to sustain between 251 and 365 horses, will be managed for zero horses. Roundups will occur if the population exceeds 200.
--The Divide Basin herd area northeast of Rock Springs, currently home to 527 horses and managed for a population of between 415 and 600 horses, will be managed for zero horses. Roundups will occur if the population exceeds 100.
--The Adobe Town herd area southeast of Rock Springs, which now has 520 horses and is managed for between 619 and 800 horses, will be managed for between 225 and 450 horses under the settlement.
--The White Mountain herd area northwest of Rock Springs, which has 246 horses, would continue to be managed for between 205 and 300 horses but with a goal of keeping the population at the low end of that range.
The BLM would consider using fertility control methods, as well as spaying mares and gelding stallions, to limit the size of the White Mountain and Adobe Town herds.