Unit 329

The Big Hole Divide anchors the northern boundary and serves as a reliable navigation reference and potential ridge-glassing route. Bloody Dick Peak and Black Mountain rise prominently within the unit, offering elevated vantage points for scanning the prairie. Peterson Lake, Skinner Lake, and several smaller lakes dot the basin and provide both water sources and visual landmarks.

The Bloody Dick drainage system and its associated peaks create distinct geographic subdivisions within the unit. Pipe Organ Rock and the Rocky Hills provide recognizable terrain features for orientation across otherwise uniform sagebrush country. These landmarks help break up the vast prairie into manageable hunting segments.

The unit spans from low 5,300-foot basin floors to nearly 10,000 feet on surrounding ridges, with most terrain clustered in the mid-elevation band. The landscape is dominated by open prairie grasslands and expansive sagebrush flats—Horse Prairie itself is the geographic heart. Moderate forest cover appears on north-facing slopes and ridgetops, primarily lodgepole and subalpine fir at higher elevations, with scattered ponderosa lower down.

The habitat transitions from dry grassland in the broad valleys to increasingly dense forest approaching the Lemhi Pass divide and Big Hole Divide. This mix of open ground and timbered ridges creates diverse terrain for pronghorn and other species.

Over 730 miles of roads traverse the unit, creating well-connected access from multiple directions. Highway 278 and secondary roads like the Bannack-Grant Road provide direct entry; the Trail Creek-Lemhi Pass Road accesses the western side. Despite good road density, the unit's vast size means interior areas can feel remote.

Most hunting pressure concentrates along perimeter access points and near towns; the broad prairie interior sees less competition. Early-season hunters should expect moderate pressure; late-season hunting offers solitude if willing to glass the exposed country from distance. Private land interspersed with public creates patchwork access—study boundaries carefully before hunting.

Unit 329 occupies the Horse Prairie North drainage basin in Beaverhead County, bounded by Clark Canyon Dam to the south, the Montana-Idaho border and Lemhi Pass to the west, the Bloody Dick-Big Hole Divide to the north, and Interstate 15 to the east. The unit encompasses the entire drainage system from Grasshopper Creek northward through the broad Horse Prairie valley and extends into adjacent basins. Small towns like Grant and Grayling sit on or near the perimeter, providing staging points for hunters.

The unit's geography is defined by the central prairie basin surrounded by moderate elevation ridges—a classic intermountain valley configuration.

Water is limited but strategically present throughout the basin. Peterson Creek, Kelly Creek, and several seasonal drainages flow through major valleys—these become critical during dry periods. Peterson Lake, Skinner Lake, and Harrison Lake provide reliable water, though seasonal availability varies.

Multiple named springs including Ryan Springs, Houlihan Springs, and Spencer Springs offer backup sources for hunters willing to locate them. The network of irrigation ditches (Cross Ranch, Inabnit Peterson, Prohosky, and others) indicates year-round water management in lower prairie areas. Hunters should prioritize water sources when planning multi-day efforts, particularly during late season.

This unit is pronghorn-focused terrain. The open prairie and sagebrush flats provide ideal habitat for long-range glassing and stalk hunting across exposed country. Early season (August-September) places pronghorn in the broad prairie basins where water is more abundant; hunt from ridgetop vantage points and plan stalks across open ground.

Rut period (September-October) concentrates animals as bucks establish territories—use this predictability to locate and approach. Late season pushes pronghorn to thermal cover in timbered foothills and north-facing slopes; focus on the forest-grassland transition zones. Water sources become critical as drying progresses; camp near reliable springs or lakes.

The rolling nature of the sagebrush allows creative approaches despite open terrain—use swales and slight ridges to mask your movement. Glass methodically from distance; once animals are located, plan approaches using terrain features to stay hidden during the final stalk.