Bison could roam year-round in large areas adjacent to Yellowstone National Park under a proposal released Monday by Montana officials who want to further ease restrictions on the iconic, burly animals.
For decades migrating bison have been slaughtered or hazed back into the park to prevent them from passing the disease brucellosis to cattle.
The plan announced Monday would allow the animals to remain year-round in the Hebgen Basin and surrounding areas of the Gallatin National Forest. To the north, some bison would be allowed year-round in the Gardiner Basin.
Current rules allow some bison to migrate to grazing areas in Montana each winter. But they must return to the park each spring — a perennial source of friction between conservationists who want more room for bison and ranchers who say they are a disease threat.
The proposed changes are certain to stoke the argument.
Some in the livestock industry already are lining up in opposition.
"They try to talk it down and say we've downgraded the disease," said John Youngberg with the Montana Farm Bureau Federation. "There's still brucellosis in those bison up there. It hasn't gone away."
The proposal for the Gardiner Basin covers an estimated 70,000 acres and would be restricted to bull bison only except during winter.
No acreage figure was available for the Hebgen Basin, where the proposal would apply to both male and female bison.
Yellowstone has one of the largest and most genetically-pure bison populations in the world. About 40 percent of the animals test positive for exposure to brucellosis, which can cause pregnant animals to miscarry their young.
No bison-to-cattle brucellosis transmissions have been recorded in the wild.
Under the administration of Gov. Brian Schweitzer, the state has steadily ratcheted back its restrictions against the animals. That's allowed the animals to enter new areas and stretched out the date by which they are returned to the park.
Now the state wants to take that a step further, eliminating the May 15 deadline for bison to be returned to Yellowstone's west side and, for bulls, the May 1 date for the north side.
Federal rules penalizing states with brucellosis infections in cattle have eased in recent years, partially defusing one of the main concerns about allowing bison on a broader landscape.
Yet many in the livestock industry remain adamant that bison pose a potential danger to cattle. They also bristle against the possibility of bison competing for grazing land and knocking over livestock fences.
Youngberg said the proposal to allow bison year-round in some areas would be in direct violation of a federal-state bison management agreement signed in 2000.
But Pat Flowers, regional supervisor for Montana Fish Wildlife and Parks said the state was abiding by the 2000 agreement. Its twin goals were to protect the livestock industry from disease and provide more opportunities for wild, free-ranging bison.
"The plan was clearly not cast in stone," Flowers said Monday. "It was intended to respond to changes in conditions and as managers that's what we're attempting to do."
State officials are soliciting comments on the proposal through Aug. 24. Public meetings are planned for Aug. 20 in West Yellowstone and Aug. 21 in Gardiner.
A final decision could be made in time for the 2012-2013 winter, said Christian Mackay, executive officer for the Montana Department of Livestock.