GMU 99 GMU 99 — Weld/Morgan/Adams Co.
Shortgrass prairie and dryland farms north of the Denver fringe — a strong pronghorn unit with plains mule deer alongside
Northeastern Colorado plains — South Platte high plains (Weld, Morgan & Adams Counties) · Last reviewed 2026-07-12
Area
1,656
sq mi
Public land
5%
approx.
Elevation
4,300–5,200
feet
Motorized
extensive
access
Overview
GMU 99 is a large block of northeastern Colorado plains northeast of the Denver metro, bounded by Interstate 76 on the north, County Road 71 on the east, US 36 on the south, and County Road 79 / 144th Avenue on the west. This is agricultural, ranch-dominated country — roughly 95% private — where pronghorn is the marquee species (about 110 animals taken at 64% success) and plains mule deer a strong second (roughly 230 deer at about 47% success), while elk are essentially incidental. Shortgrass prairie, CRP, and managed grazing hold the antelope; success here is far more about securing private-land access than about finding animals.
Terrain
Flat to gently rolling High Plains — some of the easiest walking country in the state (flat, open, and glassable). Shortgrass prairie, concentrated through the central portion, mixes with dryland and irrigated cropland, sandsage draws, CRP grassland, and scattered creek and shelterbelt bottoms.
Cover: Shortgrass prairie (roughly 10-15% of the unit, mostly central) interspersed with dryland and irrigated cropland (wheat, corn, milo), sandsage and mid-grass draws, CRP grassland improved by managed grazing, and cottonwood/shelterbelt strips along the drainages.
Landmarks: Interstate 76 (north) · County Road 71 (east) · US 36 corridor (south) · County Road 79 / 144th Avenue (west) · South Platte corridor (near the north edge) · Wiggins and Roggen farm country · central shortgrass tracts
Access
Overwhelmingly private — roughly 95% — with only a thin sliver of genuinely huntable public ground. The 'state' land shown on maps is Colorado State Trust land, which is NOT open to hunting unless the specific parcel is enrolled in CPW's Public Access Program (walk-in access), so do not assume it is huntable. Success hinges on landowner permission, a leased ranch, an outfitter, or CPW walk-in tracts. The dense county-road grid plus I-76, US 36, and the county highways make the country easy to reach and glass from, but the land beyond the fence is almost all private.
Managers: private ranch and farm, Colorado State Trust land (generally closed to hunting), scattered public
Access points: Interstate 76 · US 36 · County Road 71 · County Road 79 / 144th Avenue · county road grid throughout
Species notes
Pronghorn
common qualityThe headliner. Pronghorn thrive in this open shortgrass-and-cropland country and recent hunters filled roughly 64% of tags (about 110 animals taken) — one of the better antelope harvests in the northeast plains. Landowners are generally more willing to grant pronghorn access than deer access, making this the unit's best opportunity.
- →Glass the open shortgrass flats and crop edges from the county-road grid at first and last light, then plan a stalk on private ground you have permission for.
- →Concentrate on the central shortgrass tracts and CRP where antelope density is highest.
- →Line up private-land access or a CPW walk-in tract before the season — access is the whole game out here.
Mule Deer
common qualityA strong plains mule deer opportunity — roughly 230 deer taken at about 47% success on the sandsage draws, CRP, and cropland edges. Limited-draw like all Colorado deer, and access-limited, but a genuine second reason to hunt this unit.
- →Focus on sandsage and mid-grass draws, CRP fields, and the cover strips along drainages where plains muleys hold during the day.
- →Hunt the edges between cropland feed and brushy bedding cover early and late.
- →Secure permission on specific ranches ahead of time; deer access is harder to get than pronghorn access here.
Whitetail Deer
limited opportunityWhitetails occur in smaller numbers along the South Platte corridor near the north edge and the cottonwood/shelterbelt bottoms, mixing with mule deer. A secondary, access-dependent opportunity in the wooded riparian pockets.
- →Key on cottonwood bottoms, tree-lined drainages, and shelterbelts near the South Platte and creek corridors rather than the open prairie.
- →Hunt travel routes between riparian bedding cover and adjacent crop fields at dawn and dusk.
- →Verify which deer species your tag covers and confirm private-land permission on the bottoms.
Rocky Mountain Elk
transient lowElk are incidental on these plains — just one animal taken recently at low success. Wandering, transient animals rather than a resident herd; not a species to plan a trip around.
- →Treat any elk as an opportunistic encounter while hunting pronghorn or deer, not a target.
- →Watch large CRP blocks and cropland where a stray elk might hold.
- →Focus your effort and access work on pronghorn and mule deer instead.
Pro tips
- →Access is everything — roughly 95% of GMU 99 is private, so secure permission, a lease, an outfitter, or CPW walk-in tracts before the hunt.
- →Do not count State Trust land as huntable unless the parcel is enrolled in CPW's Public Access Program.
- →Pronghorn is the highest-odds, easiest-to-access species here — landowners grant antelope permission more readily than deer, and this unit's antelope harvest is strong.
- →Concentrate on the central shortgrass and CRP tracts for antelope; glass from the county-road grid, then hunt only ground you have permission for.
- →After rain, dirt county roads turn to gumbo — plan routes accordingly.
Watch out for
- !Roughly 95% private land — trespass risk is high; get permission in writing and know boundaries.
- !Colorado State Trust land is closed to hunting unless enrolled in CPW's Public Access Program.
- !Very little genuinely open public ground — do not assume map 'state' parcels are huntable.
- !Dirt county roads become impassable gumbo when wet.
- !Confirm which deer species your tag covers where mule deer and whitetail overlap on the bottoms.
Logistics
Easy-access plains country served by a dense county-road grid and paved I-76 and US 36. Fort Morgan and Brush sit near the north edge and offer fuel, groceries, motels, and repair; Wiggins, Keenesburg, and Greeley are within reach, and the Denver metro is close for major supply. Standard vehicles handle most dry county roads, though dirt turns to gumbo after rain. The real logistics challenge is not terrain but access — line up permission, a lease, or CPW walk-in tracts well before opening day.
Nearest towns: Fort Morgan, CO, Wiggins, CO, Brush, CO, Keenesburg, CO, Greeley, CO
Seasons & regulations
This page carries no season dates or regulations. Get current rules from the official Colorado sources:
Research sources: CPW GMU Boundary (Big Game) — geodata.colorado.gov · HuntScore — Colorado GMU 99 (Weld, Morgan, Adams) — secondary cross-check · CPW Pronghorn Hunting
FAQ
- How big is GMU 99 in Colorado?
- GMU 99 (GMU 99 — Weld/Morgan/Adams Co.) covers about 1,656 square miles, ranging from roughly 4,300 to 5,200 feet in elevation. Area is computed from the unit boundary polygon.
- How much public land is in GMU 99?
- Approximately 5% of the unit is public land. Primary managers: private ranch and farm, Colorado State Trust land (generally closed to hunting), scattered public. Always verify ownership boundaries on the ground.
- What species does the catalog list for GMU 99?
- Pronghorn, Mule Deer, Whitetail Deer, Rocky Mountain Elk. For seasons, tags, and regulations, use the official Colorado agency resources linked on this page — this page carries no regulatory information.
Put GMU 99 on your map.
Boundary lines, public/private ownership, topo, and offline maps for this unit — in Baseline Maps, free for 14 days.