Unit 424 District 424 (Region 4)
The mountain heart of the Sun River elk herd west of Augusta — Gibson Reservoir, the North and South forks, and permit-only quality on the front of the Bob.
Sun River / Rocky Mountain Front — Region 4 · Last reviewed 2026-07-12
Area
95
sq mi
Public land
80%
approx.
Elevation
4,500–9,000
feet
Motorized
limited
access
Overview
District 424 is a compact (roughly 95 sq mi) but rugged mountain unit west of Augusta, built around the Sun River canyon, Gibson Reservoir and the North and South forks of the Sun where the Rocky Mountain Front meets the Bob Marshall Wilderness complex and the Sun River Game Preserve. It is one of the three core units (with 425 and 442) of the Sun River elk herd, which has held stable at roughly 2,300 animals. This is limited-permit, quality-tier elk country: bulls migrate down from the wilderness and game preserve to winter, and access to the Sun River WMA and adjoining ground makes success highly weather-dependent. It also holds some of Montana's premier bighorn and mountain-goat habitat, all of it in grizzly country.
Terrain
Steep, folded Rocky Mountain Front terrain — the Sun River canyon and Gibson Reservoir cut through towering limestone reefs, with the North and South forks draining out of the Bob Marshall high country.
Cover: Douglas-fir and lodgepole timber on the slopes, grass-and-browse benches and avalanche brush, willow and cottonwood along the river forks, and open subalpine parks, cliffs and scree at elevation.
Landmarks: Sun River Canyon · Gibson Reservoir · North Fork Sun River · South Fork Sun River · Sun River Game Preserve · Sawtooth Ridge · Castle Reef
Access
The bulk of the district is public Helena-Lewis & Clark National Forest reached via the Sun River Canyon and Gibson Reservoir road, with trailheads leading up the North and South forks into the Bob Marshall. Note the Sun River Game Preserve is closed to big-game hunting, and the adjoining Sun River WMA is only open noon May 15–December 1 (a winter closure protects wintering elk). Private ranch and Block Management ground fills the canyon mouth and foothill approaches; arrange permission and check current BMA maps in advance.
Managers: USFS Helena-Lewis & Clark NF, private ranch + Block Management, MT DNRC state trust
Access points: Augusta staging town · Sun River Canyon / Gibson Reservoir Road · North Fork and South Fork Sun River trailheads · Sun River WMA (seasonal, opens noon May 15)
Species notes
Rocky Mountain Elk
common trophyCore unit of the stable ~2,300-head Sun River herd; a coveted limited-draw permit unit. Bulls summer in the wilderness and Game Preserve and drift down to winter, so mature-bull success rides on weather pushing elk out of the roadless refuge.
- →Draw the limited permit, then scout the canyon and fork drainages hard
- →Hunt the timber-park edges above Gibson Reservoir at first light
- →Pray for snow — cold weather is what moves wintering bulls into range
- →Be ready to hike or pack into the North/South fork country for undisturbed bulls
Bighorn Sheep
limited trophyThe Sun River canyon and its limestone reefs hold one of Montana's marquee bighorn herds; a once-in-a-lifetime limited draw with genuine trophy potential.
- →Apply for the limited permit and glass the canyon reefs and Castle Reef country
- →Look for rams on the steep limestone above Gibson Reservoir
- →Cover ground with a spotting scope from canyon vantage points
Mountain Goat
limited trophyGoats hold the cliffs and subalpine crags of the Sawtooth reef and upper drainages; a rare limited-permit hunt in steep, technical terrain.
- →Draw the tag and glass the highest cliff bands and scree
- →Plan for steep, exposed climbs to reach billies
- →Hunt early before deep snow closes the high country
Mule Deer
common qualityMountain mule deer use the open reef faces, timbered benches and high parks; bucks-only on the Forest, with above-average buck ratios along the Front.
- →Glass reef faces and open benches early and late
- →Hunt the high country before storms, then follow deer to lower browse
- →Still-hunt timbered draws during the rut
Moose
limited qualityShiras moose inhabit the willow bottoms and riparian stringers along the Sun River forks; a limited once-in-a-lifetime draw.
- →Glass willow flats and beaver-pond bottoms along the forks at dawn and dusk
- →Still-hunt riparian stringers in the timber
- →Apply for the limited permit — this is not a general opportunity
Black Bear
common opportunityBlack bear range the timbered slopes and avalanche brush. Grizzlies are common in this Front-and-wilderness terrain, so identification is critical.
- →Glass green avalanche chutes and south-facing slopes in spring
- →Positively identify species before shooting — grizzlies are protected and common here
- →Carry bear spray and store food properly
Pro tips
- →A permit here is a prize — scout the canyon and fork drainages before your hunt
- →Success on wintering bulls tracks the weather; hunt hard after a cold front
- →Respect the Sun River Game Preserve closure and the WMA's Dec 1–May 15 winter closure
- →Be prepared for steep, technical terrain and true backcountry travel
- →Carry bear spray and treat every bear as a possible grizzly
Watch out for
- !Grizzly country — NCDE recovery zone, dense bear presence up the drainages
- !Sun River Game Preserve is closed to big-game hunting; know the boundary
- !Sun River WMA is closed December 1–May 15 to protect wintering elk
- !Steep, exposed terrain and fast-changing Front mountain weather
Logistics
Augusta is the last services town before the mountains and the staging point for the Sun River Canyon; Great Falls (about 70 miles east) is the nearest full-service base and airport. The canyon road to Gibson Reservoir is the primary artery; trailheads beyond require foot or stock travel into the Bob Marshall complex.
Nearest towns: Augusta, Choteau, Great Falls
Seasons & regulations
This page carries no season dates or regulations. Get current rules from the official Montana sources:
Research sources: North-central Montana Big Game Forecast (Region 4) — Montana FWP · Region 4 Elk — FWP Commission December 2025 packet · Sun River Wildlife Management Area — Montana FWP
FAQ
- How big is Unit 424 in Montana?
- Unit 424 (District 424 (Region 4)) covers about 95 square miles, ranging from roughly 4,500 to 9,000 feet in elevation. Area is computed from the unit boundary polygon.
- How much public land is in Unit 424?
- Approximately 80% of the unit is public land. Primary managers: USFS Helena-Lewis & Clark NF, private ranch + Block Management, MT DNRC state trust. Always verify ownership boundaries on the ground.
- What species does the catalog list for Unit 424?
- Rocky Mountain Elk, Bighorn Sheep, Mountain Goat, Mule Deer, Moose, Black Bear. For seasons, tags, and regulations, use the official Montana agency resources linked on this page — this page carries no regulatory information.
Put Unit 424 on your map.
Boundary lines, public/private ownership, topo, and offline maps for this unit — in Baseline Maps, free for 14 days.