Colorado · 99 of 1,120 · BLM's list, read Oct 20, 2026
Colorado
99 areas, 863,857 acres. At least 98 of them have a claim, lease or right of way inside the line, or a grazing allotment across it.
Every Area of Critical Environmental Concern BLM's Colorado office holds, the ones with the most inside the line first. Each row opens the area's page: its line, what BLM found there and what sits inside it.
Every area, the most inside first
- East Douglas Creek ACEC47,391 acres · 25 oil and gas leases, 48 rights of way, 5 grazing allotments covering part of it78inside
- Grape Creek ACEC16,558 acres · at least 59 active mining claims and 1 more BLM lists as Filed, 2 rights of way, 6 grazing allotments covering part of it67inside
- Roan and Carr Creeks33,566 acres · 18 oil and gas leases, 15 rights of way, 23 grazing allotments covering part of it56inside
- Deep Creek ACEC4,422 acres · at least 46 active mining claims, 3 rights of way, 6 grazing allotments covering part of it55inside
- Sapinero Mesa ACEC17,242 acres · at least 39 active mining claims, 2 rights of way, 5 grazing allotments covering part of it46inside
- San Miguel River ACEC21,657 acres · at least 16 active mining claims and 1 more BLM lists as Under Review, 12 rights of way, 16 grazing allotments covering part of it44inside
- South Shale Ridge ACEC27,838 acres · 22 oil and gas leases, 9 rights of way, 7 grazing allotments covering part of it38inside
- White River Riparian ACEC901 acres · 7 rights of way, 27 grazing allotments covering part of it34inside
- Pyramid Rock ACEC (Zone 2)14,121 acres · 17 oil and gas leases, 13 rights of way, 2 grazing allotments covering part of it32inside
- Glenwood Springs Debris Flow Hazard Zones ACEC6,101 acres · at least 3 active mining claims, 18 rights of way, 4 grazing allotments covering part of it25inside
- Arkansas Canyonlands ACEC23,707 acres · at least 4 active mining claims, 8 rights of way, 12 grazing allotments covering part of it24inside
- South Pikes Peak ACEC40,449 acres · 6 rights of way, 17 grazing allotments covering part of it23inside
- The Palisade ACEC32,197 acres · 5 rights of way, 17 grazing allotments covering part of it22inside
- West Antelope Creek ACEC29,045 acres · 11 rights of way, 7 grazing allotments covering part of it18inside
- Top of the World ACEC8,741 acres · at least 6 active mining claims and 1 more BLM lists as Filed, 9 rights of way, 2 grazing allotments covering part of it17inside
- Trickle Mountain ACEC43,857 acres · 4 rights of way, 13 grazing allotments covering part of it17inside
- San Luis Hills ACEC36,472 acres · at least 3 active mining claims and 79 more BLM lists as Filed, 4 rights of way, 9 grazing allotments covering part of it16inside
- Dolores River Riparian ACEC7,428 acres · at least 2 active mining claims and 3 more BLM lists as Filed, 3 rights of way, 11 grazing allotments covering part of it16inside
- Blanca Wetlands ACEC122,660 acres · 7 rights of way, 9 grazing allotments covering part of it16inside
- Gunnison Sage-Grouse ACEC/IBA22,189 acres · 7 rights of way, 8 grazing allotments covering part of it15inside
- Anvil Points ACEC6,895 acres · 2 oil and gas leases, 6 rights of way, 7 grazing allotments covering part of it15inside
- North Park Natural Area ACEC4,460 acres · 1 oil and gas lease, 3 rights of way, 11 grazing allotments covering part of it15inside
- Mount Logan Foothills ACEC3,928 acres · 6 oil and gas leases, 6 rights of way, 3 grazing allotments covering part of it15inside
- Coal Draw ACEC1,824 acres · 7 oil and gas leases, 5 rights of way, 2 grazing allotments covering part of it14inside
- Los Mogotes ACEC33,447 acres · 2 rights of way, 10 grazing allotments covering part of it12inside
- Chance Gulch ACEC13,804 acres · at least 3 active mining claims, 6 rights of way, 3 grazing allotments covering part of it12inside
- Garden Park ACEC3,122 acres · 6 rights of way, 6 grazing allotments covering part of it12inside
- Cannonball Mesa ACEC/RNA2,436 acres · 6 oil and gas leases, 1 right of way, 4 grazing allotments covering part of it11inside
- Ruby Mountain/Railroad Gulch ACEC1,772 acres · 5 rights of way, 6 grazing allotments covering part of it11inside
- Gypsum Valley ACEC6,171 acres · at least 2 active mining claims and 9 more BLM lists as Filed, 1 oil and gas lease, 3 rights of way, 3 grazing allotments covering part of it9inside
- Oil Spring Mountain ACEC18,245 acres · 5 oil and gas leases, 2 rights of way, 2 grazing allotments covering part of it9inside
- Mesa Verde Escarpment ACEC7,420 acres · 6 rights of way, 3 grazing allotments covering part of it9inside
- River Rims ACEC5,302 acres · 1 right of way, 8 grazing allotments covering part of it9inside
- Grand Hogback Expansion ACEC8,801 acres · 1 right of way, 7 grazing allotments covering part of it8inside
- Slumgullion Earthflow ACEC1,317 acres · 5 rights of way, 3 grazing allotments covering part of it8inside
- Rio Grande River Corridor ACEC5,357 acres · at least 1 mining claim BLM lists as Filed, 1 right of way, 6 grazing allotments covering part of it7inside
- Raven Ridge ACEC5,010 acres · 2 oil and gas leases, 1 right of way, 4 grazing allotments covering part of it7inside
- Magpie Gulch ACEC4,711 acres · 1 oil and gas lease, 6 grazing allotments covering part of it7inside
- Hardscrabble - East Eagle ACEC4,152 acres · 3 rights of way, 4 grazing allotments covering part of it7inside
- Duck Creek ACEC3,472 acres · 3 oil and gas leases, 1 right of way, 3 grazing allotments covering part of it7inside
- Ryan Gulch ACEC1,442 acres · 3 oil and gas leases, 3 rights of way, a grazing allotment covering part of it7inside
- Trapper/Northwater Creek ACEC6,291 acres · 1 right of way, 5 grazing allotments covering part of it6inside
- Grand Hogback ACEC4,306 acres · 3 rights of way, 3 grazing allotments covering part of it6inside
- McElmo ACEC/RNA4,105 acres · 3 oil and gas leases, 1 right of way, 2 grazing allotments covering part of it6inside
- Blue Hill ACEC3,713 acres · 3 rights of way, 3 grazing allotments covering part of it6inside
- Atwell Gulch ACEC2,859 acres · 1 oil and gas lease, 1 right of way, 4 grazing allotments covering part of it6inside
- Paradox Rock Art ACEC1,083 acres · at least 3 active mining claims, 3 grazing allotments covering part of it6inside
- Sinbad Valley ACEC6,388 acres · 1 right of way, 4 grazing allotments covering part of it5inside
- Cucharas Canyon ACEC6,068 acres · 2 rights of way, 3 grazing allotments covering part of it5inside
- Coal Oil Rim ACEC3,191 acres · 3 oil and gas leases, 2 grazing allotments covering part of it5inside
- Irish Canyon ACEC11,922 acres · 4 grazing allotments covering part of it4inside
- East Fork Parachute Creek ACEC7,074 acres · 4 grazing allotments covering part of it4inside
- Cumbres and Toltec Scenic Railroad Corridor ACEC3,904 acres · 4 grazing allotments covering part of it4inside
- Deer Gulch ACEC1,829 acres · 1 right of way, 3 grazing allotments covering part of it4inside
- Dudley Bluffs ACEC1,618 acres · 1 oil and gas lease, 1 right of way, 2 grazing allotments covering part of it4inside
- Pyramid Rock ACEC (Zone 1)1,257 acres · 2 oil and gas leases, 1 right of way, a grazing allotment covering part of it4inside
- Ancestral Puebloan ACEC801 acres · 2 rights of way, 2 grazing allotments covering part of it4inside
- Kremmling ACEC678 acres · 2 rights of way, 2 grazing allotments covering part of it4inside
- Droney Gulch ACEC674 acres · 2 rights of way, 2 grazing allotments covering part of it4inside
- North Sand Hills ACEC487 acres · 4 grazing allotments covering part of it4inside
- Dry Creek Basin ACEC10,917 acres · 2 rights of way, a grazing allotment covering part of it3inside
- Bull Gulch ACEC10,371 acres · 3 grazing allotments covering part of it3inside
- Moosehead Mountain ACEC8,972 acres · 1 right of way, 2 grazing allotments covering part of it3inside
- Adobe Badlands ACEC6,370 acres · 3 grazing allotments covering part of it3inside
- Redcloud Peak ACEC6,093 acres · 3 grazing allotments covering part of it3inside
- South Beaver Creek ACEC4,545 acres · 1 right of way, 2 grazing allotments covering part of it3inside
- Sheep Creek Uplands ACEC3,905 acres · 3 grazing allotments covering part of it3inside
- Native Plant Community ACEC/ONA3,788 acres · 3 grazing allotments covering part of it3inside
- Ra Jadero Canyon ACEC3,652 acres · 3 grazing allotments covering part of it3inside
- Thompson Creek ACEC3,541 acres · 3 grazing allotments covering part of it3inside
- Yanks Gulch/Upper Greasewood Creek ACEC2,722 acres · 3 grazing allotments covering part of it3inside
- Badger Wash ACEC2,244 acres · 1 oil and gas lease, 2 grazing allotments covering part of it3inside
- Laramie River ACEC1,799 acres · 3 grazing allotments covering part of it3inside
- Juanita Arch ACEC1,624 acres · 3 grazing allotments covering part of it3inside
- South Cathedral Bluffs ACEC1,324 acres · 3 grazing allotments covering part of it3inside
- Troublesome Creek ACEC996 acres · 1 right of way, 2 grazing allotments covering part of it3inside
- Barger Gulch Heritage Area ACEC533 acres · 3 grazing allotments covering part of it3inside
- Rough Canyon ACEC2,779 acres · 2 grazing allotments covering part of it2inside
- Indian Creek ACEC2,345 acres · 1 right of way, a grazing allotment covering part of it2inside
- Escalante Canyon ACEC2,282 acres · 2 grazing allotments covering part of it2inside
- Sand Canyon ACEC/RNA1,777 acres · 2 oil and gas leases2inside
- American Basin ACEC1,605 acres · at least 1 active mining claim, a grazing allotment covering part of it2inside
- McCoy Fan Delta ACEC1,518 acres · 1 right of way, a grazing allotment covering part of it2inside
- Blacks Gulch ACEC801 acres · 1 right of way, a grazing allotment covering part of it2inside
- Lyons Gulch ACEC429 acres · 2 grazing allotments covering part of it2inside
- Biological Soil Crust ACEC385 acres · 2 grazing allotments covering part of it2inside
- Castle Gardens ACEC310 acres · 2 grazing allotments covering part of it2inside
- Kremmling Cretaceous Ammonite RNA ACEC197 acres · 2 grazing allotments covering part of it2inside
- Fairview ACEC/RNA161 acres · 1 right of way, a grazing allotment covering part of it2inside
- Needle Rock ACEC82 acres · 2 rights of way2inside
- Mount Garfield ACEC2,361 acres · a grazing allotment covering part of it1inside
- Elephant Rocks ACEC1,845 acres · a grazing allotment covering part of it1inside
- Gibbler Mountain ACEC1,266 acres · a grazing allotment covering part of it1inside
- Fairview South (BLM Expansion) ACEC608 acres · a grazing allotment covering part of it1inside
- Kinney Creek ACEC588 acres · a grazing allotment covering part of it1inside
- Lower Greaswood Creek ACEC203 acres · a grazing allotment covering part of it1inside
- Unaweep Seep ACEC84 acres · a grazing allotment covering part of it1inside
- Gunnison Gravels ACEC15 acres · a grazing allotment covering part of it1inside
- Dillon Pinnacles ACEC940 acres · nothing placed inside0inside
SheetColoradoLines99Acres863,857Inked1991 to 2024ReadOct 20, 2026
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