BOISE, Idaho — The Idaho Fish and Game Commission has approved an interim plan to prevent bighorn sheep and domestic sheep from mingling by creating buffer zones between the two species.

The plan, approved Thursday and immediately attacked by environmental groups, sets a March 1 deadline to create the buffer zones based on domestic sheep grazing allotments.

Those buffer zones will be determined by domestic sheep growers with grazing permits, Idaho Department of Fish and Game and state Department of Agriculture officials, and possibly federal land managers.

The plan, which does not allow public comment, also calls for hazing, capturing or killing bighorns in the buffer zones.

"It's not going to be a knee-jerk reaction to put buffer zones out there to eliminate bighorn sheep," said Brian Oakey, Agriculture Department deputy director. "I don't see that happening."

Dale Toweill, Fish and Game's program coordinator for bighorn sheep, was unsure whether buffer zones might be created that resulted in killing bighorns.

"I'm not sure anyone has an answer to that," he said. "In some areas the plan is going to work to the benefit of bighorns. In some areas it's going to work to the benefit of domestics."

The plan the Fish and Game Commission approved requires bighorn sheep to be managed to minimize population expansion into domestic sheep grazing allotments, and prohibits transplanting bighorns into areas where there is a risk they could mingle with domestic sheep.

Domestic sheep entering the buffer zones could also be killed as long as the sheep owner agreed to the action.

While the grazing allotments are on federal land, Idaho wildlife is considered state property, and bighorns are therefore managed by the state.

There are some 260,000 domestic sheep in Idaho, and they brought in more than $17 million to the state in 2006, according to the state Agriculture Department.

The population of bighorns in Idaho has dropped from about 6,500 in 1990 to about 3,500 currently, with about 2,000 Rocky Mountain bighorns, and about 1,500 California bighorns.

Jon Marvel, executive director of the Idaho-based conservation group Western Watersheds Project, said the plan has numerous problems.

"The buffer zones, let's call them extermination zones, are to be determined without public comment," Marvel said. "Even if you thought they were a good idea, creating them with secret meetings between ranchers and Fish and Game is wrong when it affects wildlife owned by all Idahoans."

William Myers is an attorney who represented the Carlson Co. over a sheep grazing allotment in the Nez Perce Forest where the sheep were ordered off last November by a federal judge because of the possibility that deadly diseases could be transmitted to wild sheep.

"(The plan) seems like a reasonable response to a tough problem," Myers said. "The state thinks bighorn sheep are important and domestic sheep are important, and they're trying to reach a balance."

In south-central Idaho, Cassia County commissioners and sheep ranchers have asked Gov. C.L. "Butch" Otter to remove bighorns from federal grazing lands.

Last fall, Otter wrote to state Agriculture Director Celia Gould and state Fish and Game Director Cal Groen, directing them to provide recommendations for handling the sheep dilemma. Those two agencies wrote the interim plan.

Otter's letter followed a series of decisions that went against domestic sheep producers in Idaho, including a May decision by the U.S. Forest Service restricting sheep grazing in some areas of the Payette National Forest after three environmental groups sued, arguing diseases transmitted by domestic sheep could kill bighorn sheep.

Pattie Soucek of the Payette National Forest said she was unsure what authority the federal government might have over state officials killing bighorns on federal land.

"I hope people don't act too quickly and start shooting bighorns without thinking it through," she said. "There are native populations in Idaho."

She said if native populations dwindle sufficiently, they could wind up on a list of threatened or endangered species and receive federal protection.