Unit 37L

The Lost River Range forms the unit's dominant western spine; its highest peaks and ridges offer glassing vantage points and natural sheep travel corridors. The Pahsimeroi Mountains anchor the east side with similar rock-and-scree character. Key summits—Castle Peak, Mount Breitenbach, Dickey Peak—mark major ridge systems.

Passes including Arco Pass, Doublespring Pass, and Horseheaven Pass provide navigation references across broken country. Borah Glacier on the Lost River Range and distinctive formations like Eagle Rock serve as unmistakable orientation points. These landmarks help organize a complex unit into manageable hunting areas.

Elevation spans from 4,600 feet in scattered valley bottoms to over 12,500 feet on high ridges, with most hunting terrain falling in the 7,000- to 10,000-foot zone. Sparse forest cover—primarily scattered conifer stands on north slopes and ridge systems—dominates above 8,000 feet; lower elevations remain open sagebrush and native bunch grass. The terrain transitions sharply from basin floors to steep scree and rocky slopes where bighorn thrive.

These elevation bands create distinct habitat zones: open lower country, timber-studded mid-elevation slopes, and exposed high-country ridges where sheep seek security.

Connected road networks total over 2,700 miles but density remains low across the vast area—roads link towns and drainages without saturating the landscape. Highway access from US-93 near Arco provides entry, but most hunting areas require rougher mountain roads. The sparse, scattered nature of these roads means multiple staging options and flexibility in approach.

The combination of challenging terrain, limited water, and high elevation keeps pressure manageable; most hunters avoid the complexity. Success hinges on embracing the remote nature and self-sufficiency.

Unit 37L encompasses a vast swath of central Idaho's high desert and mountain country, anchored by the Lost River Range to the west and the Pahsimeroi Mountains to the east. The Pahsimeroi Valley runs through the heart of the unit, with access towns including Howe, Ellis, May, and Leslie scattered along its borders. The unit sprawls across rolling high-desert terrain punctuated by ridge systems and deep canyons—classic Great Basin topography with significant elevation relief.

The sheer size and complexity of the landscape means hunters must commit to understanding their chosen area.

Water sources remain limited and scattered—a critical constraint in this semi-arid unit. Reliable creeks include Warm Spring Creek, Sheep Creek, Mill Creek, and Rock Creek, but they concentrate in specific drainages rather than grid the entire landscape. Numerous springs—Moffett Springs, Buck Springs, Camp Springs, and seasonal sources—exist but require local knowledge to locate reliably.

Reservoirs and lakes including Quake Lake, Copper Lake, and scattered alpine lakes provide water at higher elevations. Hunters must plan water sources carefully, as extended travel through dry basins is common.

Unit 37L is dedicated bighorn sheep country. Terrain complexity is high—expect steep, rocky slopes, exposed ridges, and canyons that demand scrambling ability and route-finding skill. Early season offers access to higher elevations where sheep concentrate on lush alpine forage and near reliable water; September glassing from distant ridges is standard.

Peak rut occurs mid-September through October; rams move more actively and become more vulnerable. Late season drives sheep to lower, more accessible terrain but weather becomes harsh. Successful hunts rely on glassing distant slopes, understanding drainage systems as travel corridors, and physical fitness to access steep terrain.