The federal Bureau of Land Management has approved construction of three new corrals to hold more than 8,000 wild horses captured on federal rangeland to accelerate horse roundups slowed by a lack of space in existing holding pens.

The bureau issued final decisions on environmental assessments of the plans this week for the pens in Colorado, Wyoming and Utah.

The pens are the next step in plans announced last year by the administration of President Donald Trump to speed up the capture of 130,000 wild horses over 10 years at an estimated cost of $1 billion.

Backers include the National Cattlemen鈥檚 Beef Association and American Farm Bureau Federation, which have pushed for the slaughter of excess horses that compete for forage with livestock grazing on U.S. lands.

Objecting to the corrals are wild horse advocates who insist the mustangs should remain in the wild and that the money would be better spent on horse fertility controls, like darting mares on the range with contraceptive drugs.

鈥淓xpanding capacity to hold captured mustangs is the first step to implementing this administration鈥檚 reckless plan to round up the vast majority of the West鈥檚 wild horses and burros,鈥� American Wild Horse Campaign spokeswoman Grace Kuhn said.

Her group is considering an appeal, which would have to be filed within 30 days.

The government currently holds about 50,000 horses in off-range corrals and pastures at an annual cost of about $50 million.

About 95,000 remain on the range. That is 鈥渕ore than triple the number of animals the land can sustainably support in balance with other public resource values, including wildlife, recreation, livestock grazing, energy resource development and others,鈥� the bureau said Wednesday.

With virtually no predators, the horse population can double every four to five years, the agency said. Agency officials have said the appropriate number of horses roaming free 鈥� called 鈥渁ppropriate management level,鈥� with the acronym AML 鈥� is about 27,000.

The new corrals would be built on private land and operated by contractors near Canon City, Colorado; Sutherland, Utah and Wheatland, Wyoming. An existing corral near Axtel, Utah would be expanded. The agency hasn鈥檛 provided any cost estimates.

State and county officials in Utah, Wyoming and Colorado also support expanding holding capacity.

鈥淭he creation of contracting for off-range corrals is a critical first step in the achievement of AML on the public lands,鈥� the Utah Public Lands Policy Coordinating Office said.

The Wyoming Department of Agriculture, Utah鈥檚 Beaver County Commission and Colorado鈥檚 White River and Douglas Creek Conservation Districts also filed formal comments supporting the project.

鈥淲e assert that the management of wild free-roaming horses and burros requires the BLM to constantly manage the population and herd size of these animals and that gathering excess animals as they approach AML is compulsory and necessary for health of the animals and the rangeland,鈥� the Beaver County Commission said.

Wyoming's agriculture department said a roundup there recently was suspended because there wasn鈥檛 enough room in off-range corrals.

鈥淭his event has led to the BLM not meeting its removal goals and allowing excess wild horses to remain on the range and continue to negatively impact the natural resources and rangeland health,鈥� the department said.

Mustang advocates have said the roundups are aimed at placating ranchers at horses' expense, arguing that cattle do far more damage to ranchland than mustangs.

The American Wild Horse Campaign has said that the government's population quotas are often outdated and not rooted in solid scientific data and that the mustangs must be permitted to roam ranges in federally protected management areas established under the Free-Roaming Horse and Burro Act of 1971.

鈥淚nstead of spending one billion tax dollars to round up and warehouse wild horses, the BLM should invest resources to humanely manage these iconic animals in their habitats on public lands,鈥� Kuhn said.

Neda DeMayo, president of Return to Freedom Wild Horse Conservation, said proper management of the horses will require a robust fertility control program.

鈥淪caling up fertility control as BLM鈥檚 primary management tool would reduce roundups over time,鈥� she said. 鈥淭he longer BLM delays, the greater the threat to the horses.鈥�

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