A Colorado agriculture group and Chaffee (CHAY'-fee) County have been allowed to intervene in a lawsuit challenging livestock grazing on about a quarter million acres on the Pike and San Isabel national forests in south-central Colorado.

A federal magistrate Monday approved requests by the Colorado Cattlemen's Association and the county to intervene on behalf of the U.S. Forest Service.

The Idaho-based Western Watersheds Project wants to overturn a decision reauthorizing livestock grazing on the forests. A lawsuit filed in July claims the grazing will further degrade already damaged wildlife habitat, streams and wetlands.

Forest officials have said their plan was based on the best science and information available and they will monitor conditions.

The area affected stretches from north of Leadville to south of Salida.