Colorado GMU 231 Mule Deer Hunting
Routt, Rio Blanco and Garfield counties, northwest Colorado · 178 sq mi
Based on the EASIEST unit-wide buck or either-sex hunt code available to adult Colorado residents in the 2026 primary draw — the lowest preference-point tier that drew reliably. Private-land-only and Ranching for Wildlife hunts are excluded because neither is a unit-wide public-land opportunity — NOT because the public cannot draw them. A private-land-only license requires the hunter's own permission to hunt private ground; a Ranching for Wildlife license is valid on the participating ranches enrolled in that program. They are separate systems. Other weapons, seasons and nonresident applicants can require substantially more points. The band is a floor, not a target: even the easiest qualifying hunt here sits in that range.
What hunting GMU 231 is like
GMU 231 sprawls across 178 square miles of northwestern Colorado in Routt, Rio Blanco and Garfield counties, ranging from 6,900 feet to 12,100 feet in elevation with a typical elevation around 8,900 feet. The terrain is rolling, with some steeper breaks: 52 percent of the unit is gentle, 41 percent moderate, and 7 percent steep or rugged. The country supports mule deer across its full mapped extent, though the species concentrates seasonally rather than spreading evenly through all available ground.
National Forest and BLM land comprise roughly 63 percent of the unit, or about 112 square miles, and form the reliably huntable public base. Colorado State Trust Land makes up approximately 1.1 percent, accessible only where CPW has enrolled parcels in the Public Access Program; a hunter cannot assume this ground is open. Private land accounts for about 36 percent. Access to public ground depends on existing roads and trailheads; public ownership alone does not guarantee entry.
Mule deer use the full mapped range through summer and fall. Winter Range covers about 15 percent of the unit, and Winter Concentration marks approximately 4 percent where deer cluster as conditions shift. As the season progresses through fall, hunters should expect deer to shift toward winter ground, though the timing and extent of that shift varies with weather and snow. A hunter's ability to locate concentrated deer depends on matching the season to the seasonal-range coverage and the weather conditions driving that movement.
The unit offers six seasons in total, five of which are open to public draw applicants. Archery runs September 2 to September 30 as an either-sex hunt. Muzzleloader runs September 12 to September 20 for does and bucks. Early Rifle runs September 5 to September 13 for bucks. The 2nd Rifle season runs October 24 to November 1 for bucks, and the 3rd Rifle season runs November 7 to November 15 for bucks; these are the two numbered rifle seasons. A private-land-only season from October 24 to November 15 is not available through the public draw. The September hunts occur during the velvet-shed and early-fall-transition phase. The 2nd Rifle season spans the early-fall-migration and early-pre-rut phases. The 3rd Rifle season spans early-pre-rut and primary-rut phases, timing that concentrates rut activity in mid-to-late November. Extreme hunter pressure characterizes this unit, and the easiest qualifying unit-wide buck or either-sex code draws at zero points for adult Colorado residents, making it accessible even to applicants with no preference points.
Terrain & elevation
- Elevation
- 6,900–12,100 ft, typically around 8,900 ft
- Steepness
- Moderate — mean slope 11.3°
- Slope breakdown
- 52% gentle · 41% moderate · 6% steep · 1% rugged
- Ground you can count on
- ~112 sq mi, plus ~2 sq mi of State Trust Land where access depends on enrollment
Land & access
About 63% of GMU 231 is public land a hunter can count on — National Forest and BLM. A further 1% is State Trust Land, which is huntable only where CPW has enrolled it.
- National Forest61%
- BLM2%
- State Trust Land1%
- Private36%
Colorado State Trust Land is open to public hunting only where it is enrolled in CPW's Public Access Program. Check current enrollment before planning around it.
Where mule deer live in the unit
Colorado Parks & Wildlife maps mule deer seasonal ranges statewide. This is how much of GMU 231 each range covers — the single best clue to whether mule deer are here in September, in November, or only passing through. The layers overlap, so they do not add to 100%.
- Summer Range100%used in summer
- Overall Range100%the full extent of range CPW maps for mule deer — near 100% on most units, and not a statement about when mule deer are present
- Winter Range15%used in winter
- Winter Concentration4%where mule deer bunch up in winter
- Migration Corridors<1%movement between ranges, not residence
Mule Deer seasons & weapons (2026)
| Season | Dates | Tags offered |
|---|---|---|
| Archery | September 2 – September 30 | Either-sex |
| Muzzleloader | September 12 – September 20 | Doe, Buck |
| 2nd Rifle | October 24 – November 1 | Buck |
| 3rd Rifle | November 7 – November 15 | Buck |
| Early Rifle | September 5 – September 13 | Buck |
| Private-land only | October 24 – November 15 | Either-sex |
Dates span every hunt code of that type in this unit and can differ by code. Confirm the current brochure with Colorado Parks & Wildlife before applying.
Fall weather
- September — highs around 64°F, lows around 38°F, about 0.1 in of snow (mid-elevation normals)
- October — highs around 52°F, lows around 28°F, about 4.9 in of snow (mid-elevation normals)
- November — highs around 39°F, lows around 17°F, about 19.4 in of snow (mid-elevation normals)
GMU 231 mule deer hunting FAQ
Can someone with no preference points draw a tag here?
Yes. The easiest qualifying unit-wide buck or either-sex code for adult Colorado residents draws at zero points, meaning an applicant with no preference points can draw reliably on the first application. This applies to codes and seasons within the public draw; other hunts, weapons or nonresident applicants may require substantially more points.
How much ground can a public-land hunter actually hunt?
About 63 percent of the unit, roughly 112 square miles, is National Forest and BLM land open to public hunting. Colorado State Trust Land makes up an additional 1.1 percent but is huntable only where CPW has enrolled parcels in the Public Access Program, which cannot be assumed. Access to these lands depends on the existence of roads, trailheads and seasonal closures, not ownership alone.
Is this unit realistic for someone planning to hunt early season?
Yes. Archery runs September 2 to September 30, Early Rifle runs September 5 to September 13, and Muzzleloader runs September 12 to September 20. All three fall during the velvet-shed and early-fall-transition phase when bucks are shedding velvet and feeding actively. September temperatures at mid elevation average highs around 64°F and lows around 38°F, with minimal snowfall.
When does the rut occur and which seasons overlap it?
The primary rut occurs November 11 to November 25. The 3rd Rifle season (November 7–15) spans from the early-pre-rut phase into the primary rut, giving hunters direct overlap with peak rut activity. The 2nd Rifle season (October 24–November 1) occurs before the rut and sits in the early-fall-migration and early-pre-rut phases.
Does terrain difficulty match the unit's elevation range?
The unit spans 5,200 vertical feet but does not get uniformly steep with elevation. Gentle terrain comprises 52 percent of the area and moderate terrain 41 percent, with only 7 percent steep or rugged. This rolling country with scattered breaks is hikeable for hunters on foot, though the specific approach depends on where public and private land actually adjoin.
Why is this unit easy to draw despite extreme hunter pressure?
Draw difficulty measures the preference points required for the easiest available tag, not the number of hunters competing for tags. This unit draws at zero points for its easiest codes because enough licenses are available relative to demand for those particular hunts, even though overall pressure on the unit is extreme. Hunting success and crowding depend on what hunters encounter on the ground, not on draw difficulty alone.
Data sources & methodology
- Colorado Parks & Wildlife — Big Game hunting — seasons, weapons, hunt codes and license types
- CPW — Primary Draw rules — how preference points and the hybrid draw work
- CPW — Deer statistics, draw recap and Drawn Out At reports — the point levels behind the draw-difficulty bands
- CPW — Secondary Draw — licenses remaining after the primary draw
- CPW — Maps and GIS (Species Activity Mapping) — mule deer seasonal range
- CPW — State Trust Land Finder — which State Trust acreage is enrolled and open to public hunting
- Federal and state land-ownership datasets — land ownership and access
- NOAA climate normals — fall weather
Draw difficulty is a qualitative band, not published odds — the note under the summary above states exactly which hunt code it describes. Land shares are separate, non-overlapping categories: publicly owned is not the same as open to hunting, and State Trust Land is huntable only where CPW has enrolled it. Unit data last updated August 31, 2026.