Unit 423

Sheep Reef stands as the primary alpine landmark for glassing and navigation. Notable summits including Elk Hill, Arsenic Mountain, and Sulphur Hill provide vantage points from ridge systems. Gibson Reservoir anchors the southern boundary and serves as a visual reference.

The multiple named gulches—Blacktail, Big George, and Mortimer—offer natural travel corridors and drainage-based hunting approaches. Reclamation Flats and Two Shacks Flat provide gentler terrain breaks within the steeper country.

Terrain spans medium elevations from lower sagebrush valleys near 4,500 feet to timbered ridges and rocky peaks above 8,400 feet. The unit is heavily forested throughout most of its area, with dense lodgepole and spruce-fir dominating the higher elevations and transitions to ponderosa parks at lower elevations. Steep sidehills are the dominant topographic character, making this a vertical country.

Ridge systems provide open terrain for bighorn movement and glassing opportunities, while dense timber covers most drainages.

Connected road access via Sun Canyon Road to the south provides the primary entry point, with USFS Trail 223 and Trail 128 forming the backbone of internal trail network. The unit contains about 119 miles of roads total, though many are trail-only with limited vehicle use. Reasonable trail access means the unit experiences moderate pressure near roadheads, but the steep terrain and connected but sometimes rough trail system discourages casual hunting.

Blacktail Gulch and the North Fork drainage offer logical hunting concentrations.

Unit 423 encompasses the northern Sun River drainage in Teton County, bounded by Sun Canyon Road to the south, the North Fork Sun River and Game Preserve boundary to the west, and USFS trails forming the northern perimeter. Gibson Reservoir sits at the southern terminus of this compact unit. The boundary follows natural drainages and maintained trail systems, creating a relatively contained hunting area.

Multiple named gulches and creeks define the internal topography, with the Blacktail Gulch drainage serving as a central corridor.

Multiple perennial creeks sustain the unit despite limited water sources overall. The South Fork Sun River, North Fork Sun River, Biggs Creek, Moose Creek, Circle Creek, Miners Fork, Sulphur Creek, and several others provide consistent water throughout the drainages. Medicine Springs and Scattering Springs offer reliable sources for both game and hunter logistics.

Gibson Reservoir provides surface water access at the southern boundary. Water is concentrated in drainages and named springs rather than widely distributed, making drainage selection critical for hunting strategy.

Unit 423 is dedicated bighorn sheep country. The steep, timbered ridges with rocky summits and open benches provide classic sheep habitat. Hunt ridge systems and high elevation open areas for glassing opportunities, particularly around Sheep Reef, the named peaks, and upper basin areas.

Creeks provide water for locating sheep. Early season offers higher elevation access before snow; mid to late season may push animals to lower ridge systems. Physical fitness is essential—this is vertical country.

Work drainages like Blacktail Gulch and above timberline benches where sheep congregate.