In 1971, wild horses and burros were found roaming across 53.8 million acres of Herd Areas (HAs), of which 42.4 million acres were under the Bureau of Land Management’s (BLM’s) jurisdiction. Today the BLM manages wild horses and burros in subsets of these HAs, known as Herd Management Areas (HMAs) that comprise 31.6 million acres, of which 26.9 million acres are under BLM management.
The first recorded wild horse roundup on federal rangeland took place in October 1938 on lands now administered by the Worland Field Office. The Fifteenmile HMA was established in 1985 under the direction of the Wild Free-Roaming Horses and Burros Act of 1971.
The HMA is located in the upper Fifteenmile Creek watershed approximately 30 miles northwest of Worland. It encompasses over 83,000 acres of mostly public land with some intermingled state and private lands. The HMA ranges from rolling hills to rugged canyons and badlands. The country is semi-arid with hot summers and cold winters. Precipitation averages eight inches. Sudden cloudbursts erode the area's badlands, turning the streams muddy reddish-brown. Part of the HMA lies in the Bobcat Draw Wilderness Study Area, with its colorful and intricately-carved formations known as hoodoos, goblins, mushrooms, and castles.
Bays and sorrels, along with some grays, roans and pintos, roam the range. BLM administers a wild horse population of 70 to 160 adults in the HMA.