Unit 37

Key landmarks anchor navigation and glassing opportunities: the Lost River Range and Pahsimeroi Mountains define the unit's backbone, with Mount Breitenbach, Howe Peak, and Castle Peak offering high vantage points. Quake Lake and Copper Lake provide reliable geographic references. Major basins—Sheep Pen Basin, Wino Basin, and Dodge Basin—offer open country for spotting.

Pass Creek Summit, Arco Pass, and Doublespring Pass serve as natural travel corridors. Borah Glacier marks the high country on the Lost River Range. These features create a mental map for hunters navigating steep, exposed terrain.

Terrain ranges from roughly 4,600 feet in valley bottoms to over 12,500 feet on high summits, creating distinct habitat bands. Lower sagebrush basins and desert shrublands transition through mid-elevation mixed terrain into scattered timber and rocky alpine country at higher elevations. The sparse forest signature indicates open, windswept ridges and bare rock dominate upper reaches, while lower slopes feature scattered juniper and mountain mahogany.

Sheep country typically occupies cliffs and steep rocky terrain above the timberline, with escape terrain critical across the unit's complex topography.

The 2,761 miles of roads indicate a well-connected unit despite terrain complexity, with U.S. 93 and State Highway 51 providing primary access arteries. Towns of Challis, Ellis, and surrounding communities serve as staging points. The road network suggests moderate accessibility for hunters willing to drive, but actual pressure likely concentrates on accessible lower-elevation country near road ends.

Higher sheep terrain typically requires hiking from trailheads and road-end camps. The sprawling size and rolling topography mean pressure can be spread thin—solitude is possible for hunters pushing into rougher country above road access.

Unit 37 encompasses portions of Custer and Lemhi counties in central Idaho, bounded by major drainages and natural features: Poison, Shoofly, and Jacks Creeks define western limits, while the Salmon and Pahsimeroi rivers frame eastern boundaries. The unit stretches south to the Idaho-Nevada state line and north to the Snake River, encompassing the country around Ellis, Howe, and May. This vast territory sits in the shadow of the Lost River Range and Pahsimeroi Mountains, with access corridors following U.S. 93 and State Highway 51. The complexity of the boundary reflects the unit's role as a major bighorn sheep range spanning multiple drainages.

Water availability shapes hunting strategy across this semi-arid unit. Major drainages include the Pahsimeroi River, Salmon River, and Snake River systems, though much of the interior relies on springs and seasonal creeks. Reliable sources include Warm Spring Creek, Rock Creek, Buck Creek, and Doublespring Creek.

Numerous named springs dot the landscape—Mule Spring, Scratching Post Spring, Camp Springs, and others—but require scouting to confirm seasonal flow. Scattered reservoirs and lakes (Twin Lakes, Grouse Creek Lake, Shadow Lakes) provide backup water. Planning around water sources is essential in this limited-water country.

Unit 37 is bighorn sheep territory, where success depends on high-elevation glassing and patience. Hunt steep, rocky terrain above timberline where sheep find escape routes—the Lost River and Pahsimeroi ranges hold classical sheep country with cliffs, loose shale, and sparse vegetation. Early season finds sheep in higher basins and ridges; fall migration moves animals to slightly lower elevations.

Use major landmarks and passes for navigation—terrain complexity is real at altitude. Water planning is critical; identify and confirm springs before committing to high-country camps. Expect to glass from distance and cover significant elevation gain.

The unit rewards thorough topo work and willingness to sit glass for extended periods.