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Colorado GMU 521 mule deer: terrain, access and seasons

Unit 521's terrain, access, seasons and CPW mule deer figures, with Conditions rebuilt nightly.

By Bryson, co-founder Updated

2026 season

Second rifle Oct 24–Nov 1

Every section below follows this season.

Decide

The season's licenses, draw results and harvest figures.

At a glance

Second rifle runs Oct 24–Nov 1, 2026; CPW's 2024 harvest survey put success at 48% for 197 hunters.

Size
508 sq mi
CPW unit boundary, 2025
Counties
Delta, Gunnison
Elevation
5,380–13,060 ft
USGS 3DEP, 2026-10-19
Huntable public land
75%
COMaP, 2026-10-12
Second rifle license, 2026
Draw buck
CPW 2026 big game brochure. Colorado has no OTC mule deer license
Success
48%
CPW harvest survey, 2024
Hunters
197
CPW harvest survey, 2024
Hunter-days per sq mi
1.7
CPW, 2024
Road miles, any vehicle
152 mi
MVUM + CDOT, open on the Oct 24 opener
Median Habitat Score
2.3 of 5
Ranks 27th of 156 for second rifle. Glassline, v4, 2026-10-19
Snow now
1 in
Deepest at Schofield Pass SNOTEL, 2026-10-20

In short

A mid-elevation, mostly timbered draw-only unit with more far-from-road ground than most units. Most of Unit 521 sits between 7,000 and 9,000 feet, with more aspen than anything else and shrubland next, then conifer. About three-quarters of the unit is huntable public land, and just under a third of that ground is more than an hour and a half on foot from a drivable road. CPW's survey counted 463 hunters across all seasons in 2024, up from 456 in 2022, while second rifle success rose from 28% to 48%. Every license here is drawn, as for all Colorado mule deer.

Licenses and draw

Second rifle in Unit 521, 2026: a draw buck license (D-M-052-O2-R).

  • D-M-052-O2-R buck, draw 2026 draw: drawn on choice 2 for residents and nonresidents

CPW 2026 big game brochure; CPW primary-draw recap and drawn-out-at reports, 2024–2026, adult licenses. Every year of draw results is under Hunt codes and draw results.

Plan

The map, Conditions, access, hunt codes and draw results for the season, and what the research says.

Map

The interactive map (public land by manager, roads by vehicle class, burns, trailheads, SNOTEL stations, terrain and CPW's mapped ranges) needs JavaScript. The outline shows where Unit 521 sits among its neighbors.

53 43 52 421 431 521

Public data only. The plan lives in the app. Map sources

Conditions

As of Oct 21: 1 in of snow at Schofield Pass SNOTEL, the deepest reading near the unit; extreme drought (D3) on the US Drought Monitor over 72.6% of the unit.

Rebuilt nightly; sources at the end of the page.

Item Value Data
Snow (SNOTEL) Overland Res. (9,890 ft): 0 in deep, SWE 0.1 inSchofield Pass (10,640 ft, 3.3 mi out): 1 in deep, SWE 0.2 inNorth Lost Trail (9,190 ft, 3.8 mi out): 0 in deep, SWE 0.2 in 2026-10-20 2026-10-20
Drought D3, Extreme droughtShare of the unit: D0 or worse 100% · D1 or worse 100% · D2 or worse 100% · D3 or worse 72.6% USDM 2026-10-13 USDM 2026-10-13
Greenness vs normal, Sep 14–29 95% of the September normal (2014–2023), MODIS 16-day composite 2026-09-29 2026-09-29

7-day forecast

NWS 7-day gridpoint forecast for 8,000–9,000 ft and 10,000–11,000 ft, issued Oct 21; the second rifle opener, Oct 24, is marked; no front named in the NWS discussion for the 7 days.

8,000–9,000 ft NWS GJT gridpoint 134,97, issued 2026-10-21. Gusts and lows: gridpoint only. No front named in the NWS discussion for the 7 days.
Wed 10/21 Thu 10/22 Fri 10/23 Sat 10/24 Opener Sun 10/25 Mon 10/26 Tue 10/27
High / low 59° 37°60° 44°56° 38°57° 35°54° 35°55° 34°56° 32°
Precip 0.2 in1 in0.2 in0.1 in0.1 in0 in0 in
Snow 0 in0 in0 in0 in0 in0 in0 in
Gusts 14 mph17 mph22 mph10 mph9 mph7 mph12 mph
10,000–11,000 ft NWS GJT gridpoint 130,99, issued 2026-10-21. Gusts and lows: gridpoint only. No front named in the NWS discussion for the 7 days.
Wed 10/21 Thu 10/22 Fri 10/23 Sat 10/24 Opener Sun 10/25 Mon 10/26 Tue 10/27
High / low 47° 37°47° 41°44° 34°44° 33°42° 33°43° 32°43° 30°
Precip 0.3 in1.1 in0.2 in0.2 in0.1 in0 in0 in
Snow 0 in0 in0 in0 in0.1 in0 in0 in
Gusts 14 mph17 mph26 mph10 mph9 mph6 mph10 mph

Access

Unit 521 has 9 trailheads and about 152 miles of road any vehicle may drive on the second rifle opener, plus 66 more that need high clearance. Just under a third of the huntable public ground is within a 30-minute walk of a drivable road, and just under a third is more than an hour and a half away.

Trailheads
9
COTREX, computed 2026-10-19
Road miles open, second rifle opener Oct 24–Nov 1, by the smallest vehicle allowed. MVUM plus county and state roads.
Vehicle Miles
Any vehicle
152 mi
High clearance
66 mi
4x4
0 mi
Walking time from a drivable road Share of huntable public ground by foot time from the nearest drivable road. Foot time at a standard pace on Glassline's travel model (slope, vegetation, trails), from the nearest highway, road a high-clearance vehicle can drive, or trailhead, with every road open.
Walking time Share
Within 30 min
30.8%
30–60 min
22%
60–90 min
16.6%
Over 90 min
30.6%

Hunt codes and draw results

1 hunt code for second rifle, 2026, with CPW's primary-draw results for 2024–2026.

Hunt code Year Licenses Residents Nonresidents
1st-choice applicants Drawn Drawn out at 1st-choice applicants Drawn Drawn out at
D-M-052-O2-R buck 2024 495 281 267 0 points 164 92 0 points
2025 650 310 334 Choice 2 154 165 Choice 2
2026 700 286 301 Choice 2 256 258 Choice 2

Hunt codes from the CPW 2026 big game brochure. A code valid in several units counts every hunter in all of them.

Draw results are CPW's primary-draw recap and drawn-out-at reports, 2024–2026, adult licenses. "Drawn out at" is the lowest preference-point level that drew a license; "Leftover" means licenses remained after the draw. A code valid in several units counts every applicant for all of them. Source: CPW draw reports, 2024–2026.

What the research says for this season

Findings from published studies and agency work, as tendencies. They describe how mule deer have behaved where they were studied, not where they are in Unit 521.

  • In a south-central Wyoming herd, mature bucks moved away from motorized routes into roadless cover during a rifle season while does stayed on their usual forage, and hunting barely changed when deer migrated.

    Rodgers et al., 2021 Single study

  • In Colorado's Gunnison Basin, GPS-collared mule deer made their fall migration from late October into early November, along corridors averaging about 17 miles.

    Kauffman et al., 2024 Single study

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POIs are terrain candidates — places worth checking, not animal locations.

Reference

Terrain, the multi-year numbers, neighbors and sources. Each opens in place.

Terrain and habitat

5,380–13,060 ft; aspen 34.9% and shrubland 26.1%; no mapped burns since 2020.

Unit-wide figures, computed 2026-10-19.

Elevation Acres per 1,000 ft band. USGS 3DEP.
  1. 5k–6k ft 6,690 ac
  2. 6k–7k ft 20,420 ac
  3. 7k–8k ft 82,640 ac
  4. 8k–9k ft 104,250 ac
  5. 9k–10k ft 67,450 ac
  6. 10k–11k ft 32,480 ac
  7. 11k–12k ft 8,230 ac
  8. 12k–13k ft 1,000 ac
Table view
BandAcres
5,000–6,000 ft6,690 ac
6,000–7,000 ft20,420 ac
7,000–8,000 ft82,640 ac
8,000–9,000 ft104,250 ac
9,000–10,000 ft67,450 ac
10,000–11,000 ft32,480 ac
11,000–12,000 ft8,230 ac
12,000–13,000 ft1,000 ac
Slope Share of the unit per slope class.
  1. Under 5° 12.4%
  2. 5–15° 44.7%
  3. 15–25° 24.6%
  4. 25–35° 12.1%
  5. 35°+ 6.2%
Table view
Slope classShare
Flat (under 5°)12.4%
Gentle (5–15°)44.7%
Moderate (15–25°)24.6%
Steep (25–35°)12.1%
Very steep (35° and up)6.2%
Aspect Share of non-flat ground facing each way.
  1. N 8%
  2. NE 10.8%
  3. E 13.3%
  4. SE 13.6%
  5. S 16.2%
  6. SW 15.6%
  7. W 13.8%
  8. NW 8.7%
Table view
AspectShare
North8%
Northeast10.8%
East13.3%
Southeast13.6%
South16.2%
Southwest15.6%
West13.8%
Northwest8.7%
Vegetation LF2024 existing vegetation, groups of 1% or more.
  1. Aspen 34.9%
  2. Shrubland 26.1%
  3. Conifer 21.9%
  4. Grass & meadow 4.5%
  5. Pinyon-juniper 4.2%
  6. Riparian & wetland 3.1%
  7. Rock & scree 2.7%
  8. Farmland 1.2%
Table view
Vegetation groupShare
Aspen34.9%
Shrubland26.1%
Conifer21.9%
Grass & meadow4.5%
Pinyon-juniper4.2%
Riparian & wetland3.1%
Rock & scree2.7%
Farmland1.2%
Item Value Data
Burns No burned acres in the unit since 2020 NIFC NIFC
Openings in timber 650 openings of 1–40 ac, from lidar covering 16.1% of the unit 2026-10-19 2026-10-19
Habitat Score, second rifle Share of 244,000 ac of huntable public ground in each score band. Median 2.3. Scoring v4, computed 2026-10-19.
Table view
ScoreShare of scored ground
0–0.50%
0.5–10.3%
1–1.55.4%
1.5–225.1%
2–2.533.2%
2.5–321.6%
3–3.511.4%
3.5–42.9%
4–4.50%
4.5–50%

Glassline's Habitat Score grades terrain and habitat for the season on food, water, breeding and shelter. Shown here as one distribution for the whole unit, never a map: it grades ground, not animal locations.

The numbers

CPW harvest estimates 2022–2024 for the chosen season and all seasons, the South Grand Mesa herd (D-51) estimate for 2025 and hunter density, 2024.

Second rifle success rose from 28% to 48% between 2022 and 2024, while the season's hunters fell by just over a quarter. Across all seasons, hunters held about steady between 2022 and 2024. Unit 521 is one of 3 units in CPW's South Grand Mesa mule deer herd (DAU D-51), estimated at about 9,300 mule deer after the 2025 hunt, with 34 bucks per 100 does.

Hunters, harvest and success
Season Year Hunters Harvest Success
Second rifle 2022 272 77 28%
2023 216 75 35%
2024 197 94 48%
All seasons 2022 456 160 35%
2023 443 149 34%
2024 463 213 46%

CPW deer harvest reports, 2022–2024. A dash: not reported.

Item Value Data
Hunter density 4 hunter-days per sq mi, all seasons CPW 2024 CPW 2024
Herd estimate (South Grand Mesa, D-51) 9,250 post-hunt · 8,230 in 2019 CPW 2025 CPW 2025
Buck:doe ratio 34 bucks per 100 does CPW 2025 CPW 2025

CPW harvest figures are survey estimates, not counts, and they cover the whole unit, private land included. Source: CPW harvest reports, 2022–2024.

Herd numbers cover the whole South Grand Mesa herd unit (D-51), which also takes in Units 52 and 411: CPW manages herds, not units. Source: CPW post-hunt population estimate, 2025.

Neighbors

Units 53, 43, 52, 421 and 431, nearest first.

From each unit's own page; dates there.

What this page can't tell you

Closures, private ground, this year's pressure and animal locations.
  • Closures. Forest, fire and road closure orders change through the season and aren't checked here. The managing agency's current order governs.
  • Private ground. Land with no public hunting access is hunted only with the owner's permission, and the public-land share above leaves it out.
  • This year's pressure. CPW's hunter numbers run a year or more behind the season you're planning.
  • Animal locations. These are terrain, access, harvest and herd figures, and CPW's mapped ranges are range lines; none of them places an animal.

Sources

23 datasets and studies, dated where the source dates them.
  1. Deer statistics: population estimates and harvest reports — Colorado Parks and Wildlife
  2. Colorado big game hunting: brochure, seasons and hunt codes — Colorado Parks and Wildlife
  3. Game Management Unit boundaries (Hunting Atlas) — Colorado Parks and Wildlife On the map: unit boundaries, 2025.
  4. COMaP: Colorado Ownership, Management and Protection — Colorado Natural Heritage Program, 2026-10-12 On the map: public land by manager, mapped 2026-07-29.
  5. 3D Elevation Program (3DEP), 1/3 arc-second — U.S. Geological Survey On the map: shaded relief from 5 m and 10 m lidar elevation, mapped 2026-10-04; elevation bands and slope, mapped 2026-10-04.
  6. LANDFIRE Existing Vegetation Type (LF 2024) — U.S. Geological Survey / USDA Forest Service, LF2024
  7. 3DEP lidar point clouds (canopy height model) — U.S. Geological Survey
  8. COTREX: Colorado Trail Explorer — Colorado Parks and Wildlife On the map: trailheads, 2024.
  9. Motor Vehicle Use Maps (MVUM) — USDA Forest Service On the map: roads by vehicle class, drawn as open on the selected season's opener, mapped 2026-08-22.
  10. Highways and major roads — Colorado Department of Transportation On the map: highways, mapped 2026-07-31.
  11. SNOTEL network: daily snow depth and snow water equivalent — USDA Natural Resources Conservation Service, 2026-10-20 On the map: SNOTEL stations.
  12. U.S. Drought Monitor — National Drought Mitigation Center, 2026-10-13
  13. MOD13Q1 vegetation indices (NDVI), 250 m 16-day — NASA LP DAAC, 2026-09-29
  14. National Weather Service 7-day gridpoint forecast — National Weather Service, 2026-10-21
  15. National Weather Service Area Forecast Discussion (BOU, GJT, PUB) — National Weather Service, 2026-10-21
  16. Influence of well pad activity on winter habitat selection patterns of mule deer — Sawyer, Kauffman and Nielson, Journal of Wildlife Management 73(7), 2009
  17. Sex-specific behaviors of hunted mule deer during rifle season — Rodgers, Sawyer, Mong, Stephens and Kauffman, Journal of Wildlife Management 85(2), 2021
  18. Ungulate migrations of the western United States, volume 4 — Kauffman, Lowrey, Beaupre and others, USGS Scientific Investigations Report 2024-5006, 2024
  19. Mule deer (Odocoileus hemionus) fact sheet — USDA Natural Resources Conservation Service, Colorado, Fact sheet, March 2000, 2000
  20. Timing of seasonal migration in mule deer: effects of climate, plant phenology, and life-history characteristics — Monteith, Bleich, Stephenson, Pierce, Conner, Klaver and Bowyer, Ecosphere 2(4), 2011
  21. Wildland Fire Interagency Geospatial Services (WFIGS) fire perimeters — National Interagency Fire Center On the map: burns over 100 acres since 2020, mapped 2026-06-29.
  22. Gazetteer files, places — U.S. Census Bureau, 2024 On the map: towns, 2024.
  23. Species Activity Mapping: mule deer seasonal ranges — Colorado Parks and Wildlife, 2025 On the map: CPW mapped ranges, 2025.

Build a plan for Unit 521, free.

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POIs are terrain candidates — places worth checking, not animal locations.