The lawsuit alleges the BLM has failed to comply with the Wild Horses and Burros Act of 1971 by not controlling the number of wild horses on BLM rangeland as well as on private and state lands.
The ranges are deteriorating as wildlife, horses and livestock compete for scarce grasses, brush and water, the ranchers say.
Horses have damaged range improvements made by ranchers, such as fences, springs and other water developments, the lawsuit says, and ranchers have had to haul extra water and feed to their animals as well as cut back on their grazing.
"Many plaintiffs have maintained their livelihoods via ranching operations for multiple generations. Due to economic limitations and the fact that the wild horses are federally protected, plaintiffs can do nothing to prevent damages to their private and the public rangelands," the lawsuit says.
Mark Wintch, a rancher in the Wah Wah Valley west of Milford, is president of the rancher association. "We're simply asking that they stay within their own management plan and quit abusing us," Wintch said.
The BLM acknowledges there are 14,000 more wild horses in the West than the ecosystems can maintain, but pleads poverty in regards to doing anything about them.
The agency announced last year that it would not do roundups this year because it lacks the money, particularly for long-term pasturing of wild horses.
By congressional decree, they can't be euthanized.
The BLM's own target numbers for wild horses in the West is 26,000, but there are now nearly 40,000, the agency says on its website.
Even though the agency said it has no plans to round up horses this year, state BLM directors, under pressure from ranchers and local leaders, are asking to remove more than 6,000.
Utah's Palma wants more than $500,000 to remove more than 1,000 horses from BLM, private and School and Institutional Trust Lands Administration lands in Iron and Beaver counties this summer.
Two of the lawsuit plaintiffs graze their livestock in Emery County, where wild horses in the Muddy Creek herd management area also are over the BLM limits.
In Beaver and Iron counties, where most of the plaintiffs live and ranch, the BLM's own prescribed limit on horses is just over 600.
Ranchers say there are thousands of horses, however, and it now appears, from internal and environmental assessment documents, that BLM acknowledges at least 1,800 horses on and outside the nine herd management areas in that region.
The lawsuit points to the wild horse act's requirement that the BLM inventory set limits and "immediately remove excess animals from the range so as to achieve appropriate management levels."
Karen Budd-Falen, a Cheyenne, Wyo., attorney representing the ranchers, said Thursday that similar lawsuits are being prepared for Wyoming and New Mexico ranchers. "The BLM has got a statutory duty to move," she said.
Kiersty Loughmiller, of Salt Lake City, is the Utah attorney for the ranchers. Judge Paul Warner was assigned to the case.
Horse advocates fax Utah's governor
Utah Gov. Gary Herbert's office couldn't confirm that it had received 7,000 faxes since Wednesday from wild horse advocates, as claimed by the American Wild Horse Preservation Campaign.
The coalition challenges the governor's recent statement that state government should manage wild horses.
The governor's office has a single fax machine, and it ran out of toner after 62 faxes were received, a spokesman said.
Read more about the issue and the campaign's position in "Under pressure, Utah BLM fast-tracks plea to round up wild horses."