WILDLIFE -- A federal court has blocked thousands of domestic sheep from being released to graze in eastern Idaho where environmental groups say they jeopardize a small herd of bighorn sheep with deadly viruses, the Associated Press reports.

U.S. Magistrate Judge Candy Dale on Monday granted the temporary restraining order sought by Western Watersheds Project and WildEarth Guardians in a lawsuit filed last month against the U.S. Forest Service.

The groups contend the grazing of sheep owned by the University of Idaho via permits issued to the U.S. Department of Agriculture’s Sheep Experiment Station risks transmitting diseases to bighorn sheep.

Dale in the 31-page ruling says the environmental groups established the likelihood of irreparable harm to the bighorns.

The U.S. Forest Service didn’t return a call from The Associated Press on Tuesday.