The Payette National Forest has released a set of proposed updates to its plan to keep domestic sheep from intermingling with wild bighorns, a species susceptible to pneumonia that can be passed along by their domestic cousins.
Forest officials are taking public comment on the 184-page document that spells out five new alternatives to keep the herds segregated. It also includes the latest scientific analysis on the health risks wild bighorns face in sharing habitat with domestics.
Forest managers have been working to update the plan since 2005 when the chief of the U.S. Forest Service declared that the previous plan failed to adequately protect wild sheep in north-central Idaho.
The draft, citing field observations and scientific research, finds bighorn sheep have a high probability of contracting fatal pneumonia after contact with domestic sheep.
One alternative in the draft plan calls for reducing domestic grazing by about 60 percent in Hells Canyon and allotments in the Salmon River Canyon.
"We want to keep the contact rate as low as possible, 2 to 5 percent is where you would prefer that number to be," Patty Soucek, a planner for the forest, told the Lewiston Tribune. "The higher the contact rate, the less likely the (bighorn) population is going to persist."
The draft's alternatives also include extremes for grazing, from an all-out ban on domestic grazing to no reductions.
Suzanne Rainville, supervisor of the Payette National Forest, said the new document also focused on plugging in information from about 15 years of data gleaned from bighorn sheep fitted with radio collars.
"Instead of trying to assume what bighorns will do, we said we have all this information, let's use that to tell us what they have done and make as few assumptions as possible," she said.
Environmental groups, the Nez Perce Tribe and bighorn advocates said any new policy approve by the Payette National Forest could have broader implications in other western states where bighorns may have contact with domestic sheep.
Jon Marvel, executive director of the Hailey-based Western Watershed Projects, said the decision made on the Payette forest could have far-reaching implications for management of domestic sheep across the West.
"And that will be, I think, a very good thing because there are so many places where we have this kind of conflict," he said.
Idaho bighorn numbers have dwindled by half since 1990, to about 3,500 animals. Many wildlife scientists are convinced contact between domestic sheep and bighorns reintroduced into the region in the 1970s is behind deadly disease outbreaks. Disease transmission concerns figured prominently in an Oct. 14 federal court ruling that banished a rancher from his family's historic grazing ground along the Salmon River.
The forest is taking public comment through March 19 before issuing a final decision later this year.