Unit 50-1X

Borah Glacier marks the highest terrain and provides a distinctive navigation reference. Major summit complexes including Arco Peak, Mackay Peak, and the White Knob Mountains dominate the skyline and serve as glassing platforms. Timbered Dome and Castle Rock offer excellent vantage points for surveying lower country.

The Pahsimeroi Mountains and Boulder Mountains define major ridgelines. Notable basins—Copper Basin, Spring Basin, Blizzard Basin—concentrate game movement and provide logical hunting focal points. Lake clusters (Betty, Wildhorse, Golden, Boulder lakes) mark reliable water sources in upper elevations, critical for route planning.

Terrain rises from roughly 5,200 feet in valley bottoms to over 12,500 feet at high peaks, creating distinct habitat zones. Lower elevations feature sagebrush flats and rolling basin country—open terrain interspersed with juniper and scattered timber. Mid-elevations (7,000-9,500 feet) transition to mixed conifer forest with meadows and aspen stands.

Higher ridges support sparse alpine vegetation and rocky talus. The volcanic landscape includes extensive lava flows and fractured basalt that create natural barriers and travel corridors. Forest cover remains sparse overall, offering good visibility for glassing but limited shelter in exposed basins.

The unit maintains an extensive network of Forest Service roads and trails—over 2,200 miles of road access—providing surprising connectivity despite remote appearance. However, road density remains moderate to low across the vast area, concentrating pressure on accessible drainages near trailheads and developed springs. Main access follows Highway 20-26 corridor and feeder roads into major canyons.

Pressure increases around populated areas (Arco, Mackay, Houston) and established camping zones. The terrain complexity and elevation changes mean hunters willing to push beyond easy access find significantly less competition. Upper basin and high-ridge country sees minimal pressure.

Unit 50-1X encompasses portions of Blaine, Butte, and Custer counties within the Big Lost River drainage and upper South Fork Boise River watershed. Boundaries follow U.S. Highway 20-26 on the south, the Camas Creek-Boise River watershed divide on the west, and Forest Service trails north of the Copper Creek-Cottonwood Creek divide. The unit spans from Anderson Ranch Reservoir and Lime Creek drainage in the south to the Pahsimeroi Mountains and White Knob Mountains in the north.

Major towns like Arco, Mackay, and Lost River provide supply points, though much of the unit sees minimal development beyond historic ranching infrastructure.

Water availability is limited and seasonal—critical to hunt success. The Big Lost River and South Fork Boise River anchor major drainages but flow through deep canyons. Reliable springs include Slaughterhouse Springs, Scratching Post Spring, and Pecks Canyon Spring; these concentrate game, especially during dry periods.

Smaller creeks (Park, Deer, Twin Bridges, Lake creeks) provide intermittent water but often diminish by mid-season. Reservoirs and lakes (Round Lake, Mud Lake, Combe Reservoir, Wildhorse Lakes) offer reliable water in upper basins. Lower valley areas feature extensive canal systems reflecting historic irrigation but these aren't consistent hunting water sources.

White-tailed deer inhabit this unit across multiple elevation zones, with summer range in high basins and ridges (8,000+ feet) and fall/winter movement to lower sagebrush flats and timber. Early season hunting targets cool-weather deer in upper meadows and aspen groves, glassing from named peaks and ridgelines. Rut timing drives mid-season strategy around the limited water sources—springs concentrate bucks during dry periods.

Later season requires dropping into lower elevations and canyon bottoms as snow forces game down. Success depends on finding water, scouting multiple elevations before season, and using the extensive trail network to access terrain most hunters skip. Self-sufficiency and multi-day camps pay dividends in this complex, spread-out country.