Sheep ranchers in Idaho and other states are suing the U.S. Forest Service over a bighorn sheep protection plan that reduces domestic grazing in the Payette National Forest.

The Idaho Wool Growers Association, joined by individual ranchers and industry groups from other western states, filed the lawsuit in Boise's U.S. District Court last week. The lawsuit targets the 2010 grazing reduction plan, which is predicated on the idea that bighorn sheep contract pneumonia when they come into contact with domestic sheep.

The Lewiston Tribune reports that the sheep ranchers claim in the lawsuit the federal agency failed to consider several key issues when it created the plan, including the effect that reintroduced wolves have on bighorn sheep and ways to possibly increase bighorn sheep immunity to domestic diseases.