Unit 50

Key landmarks anchor navigation across this rolling terrain. Timbered Dome, Arco Peak, and Mackay Peak serve as skyline references visible from multiple vantage points. The Pahsimeroi Mountains and Boulder Mountains define the eastern and western boundaries.

Several high basins—Copper Basin, Spring Basin, and Swensen Basin—offer glassing platforms. Named passes including Arco Pass, Beaverland Pass, and Doublespring Pass break the ridgelines. Borah Glacier and North Crater Aa Flow provide distinctive visual markers.

These features help orient hunters across terrain lacking dense forest screening.

Elevation spans from 5,200 feet in the lower drainages to over 12,500 feet in the high country. Habitat transitions from sagebrush and grass-covered lower slopes through scattered timber zones into sparse forest in the upper basins and ridgetops. The median elevation around 7,300 feet characterizes the core hunting terrain—rolling country with intermittent forest cover.

Higher elevations support alpine meadows and timbered basins where moose congregate. Lower terrain remains primarily open, with vegetation concentrated along riparian corridors and scattered draws where water and browse intersect.

Over 2,200 miles of roads traverse the unit, providing connected access from surrounding highways. Road density supports vehicle approach to multiple staging areas, though substantial terrain still remains roadless. The connected access network means pressure distributes across the unit during opener and prime season.

However, terrain complexity and rolling topography reward hunters willing to leave staging areas and hunt ridge systems and basin interiors. Higher elevations and rougher terrain see less pressure than lower road-accessible drainages. Navigation skills matter—this isn't straightforward country.

Unit 50 encompasses the Big Lost River drainage north of U.S. Highway 20-26, spanning portions of Blaine, Butte, and Custer counties in central Idaho. The southern boundary follows Anderson Ranch Dam and Lime Creek upstream to the Middle Fork Lime Creek and Forest Service Trail 050, while northern boundaries align with the South Fork Boise River-Camas Creek watershed divide. Nearby towns including Arco, Mackay, and Lost River provide staging points.

The unit is defined by the Big Lost River system and its tributary network—substantial terrain spanning high basins down to mid-elevation valleys.

Water is scattered but present. The Big Lost River and South Fork Boise River provide perennial flow through major drainages. Upper-country lakes including Wildhorse Lakes, Betty Lake, Boulder Lake, and Moose Lake hold water seasonally.

Springs including Slaughterhouse Springs, Pecks Canyon Spring, and Walker Spring support wildlife but require scouting to locate reliably. Numerous smaller creeks—Park Creek, Deer Creek, Grant Creek, Timber Creek—flow through canyons but go dry during late season. Understanding water distribution is critical for locating moose in this vast terrain; elk and moose concentrate near reliable sources.

Unit 50 is moose country characterized by rolling high-elevation terrain and scattered timber. Moose favor the upper basins and timbered areas where they can access browse and water—focus on Spring Basin, Copper Basin, and higher drainage systems. Early season hunting targets moose in high meadows before weather forces descent.

Rut activity concentrates around mid-September in areas near reliable water sources. Late season moose push lower into sagebrush and willows along creek corridors. Glassing from ridges and passes to locate animals is essential given the open nature of much terrain.

Success depends on finding and stalking individual animals rather than expecting high densities.