Unit 50

Key navigation features include Arco Peak and Mackay Peak—prominent summits providing orientation across the unit. The Pahsimeroi Mountains and Boulder Mountains anchor the terrain structure. Multiple named lakes (Wildhorse, Boulder, Moose, Angel, North Fork) offer water reference points and potential camp locations.

Borah Glacier and the North Crater Aa Flow provide unusual high-country markers. Several named passes—Arco, Doublespring, Antelope, Beaverland—serve as traditional travel corridors. Park Canyon, Slide Canyon, and Big Rocky Canyon offer drainage routes for foot travel and water-finding.

These features are critical for navigation in terrain complexity this high.

Elevation spans from the mid-5000s to above 12,500 feet, creating distinct habitat zones. Lower basins—Copper, Spring, Blizzard, and others—support sagebrush and scattered juniper, transitioning into sparse ponderosa and Douglas-fir on mid-elevation slopes. Higher ridges and summits feature alpine tundra and krummholz.

The sparse forest designation means open ridge systems dominate, with timber concentrated in creek bottoms and protected north-facing slopes. This openness creates excellent glassing country but limited shelter. Elevation extremes suggest significant seasonal movement patterns for elk and deer.

Over 2,200 miles of roads thread through this vast unit, providing connected access via Forest Service routes. The road network suggests reasonable staging from towns like Arco and Mackay on the unit's periphery. Despite connected road access, the unit's size and terrain complexity likely distribute pressure; hunters staying near trailheads and lower-elevation roads may miss the high-country opportunities.

The sparse forest and open ridges suggest visibility-based hunting and glassing will outperform timber-stalking tactics. Terrain complexity of 8/10 indicates this isn't beginner country—solitude is available for those willing to climb and cover distance.

Unit 50 encompasses portions of Blaine, Butte, and Custer counties within the Big Lost River drainage north of U.S. 20-26. The unit's southern boundary follows the highway corridor and watershed divides between the Big Lost River and South Fork Boise River drainages. Eastern and northern boundaries track the Camas Creek-South Fork Boise River watershed divide, while the western edge follows Lime Creek and its tributary system. This positioning places the unit at the intersection of the Pahsimeroi and Boulder mountain ranges, creating complex terrain that extends from low desert-influenced basins to true alpine country.

Despite the badge for limited water, the unit contains perennial features worth targeting: Slaughterhouse Springs, Walker Spring, and Jenson Spring are named reliable sources. Park Creek, Left Fork Wildhorse Creek, and multiple tributaries run seasonally or perennially, particularly at higher elevations. Lower basins (Copper, Blizzard, Spring) may run dry mid-season.

The Swamps and Iron Bog provide marshy water sources in select locations. Thousand Springs offers concentrated water access. Strategy should center on high-elevation springs and creek systems during dry periods; lower basins may require backcountry water filtering.

Water scarcity makes spring location critical for multi-day hunts.

This unit supports elk, deer, pronghorn, and possibly bighorn sheep based on terrain—confirm current species seasons before hunting. Higher elevations (9,500+ feet) hold elk during summer and early season, with migration corridors following canyon systems like Park, Slide, and Big Rocky. Mid-elevation basins and flats (Copper Basin Flat, Barton Flats) attract pronghorn and mule deer.

Rut hunting focuses on high ridges and alpine basins where animals concentrate. Early season demands high-elevation approach and water-source hunting. Late season follows migrations downslope toward winter range and lower-basin thermal cover.

The open country rewards glassing from ridge systems and high vantage points; match hunting strategy to elevation bands as seasons progress.