Colorado · Area of Critical Environmental Concern
Thompson Creek ACEC
BLM found a natural system, a scenic value and a historic value here, and its plan calls for special management. BLM's records place no claim, lease or right of way inside the line today, and three grazing allotments cover part of it. It covers 3,541 acres and was designated October 17, 2024, in the 2024 Colorado River Valley RMP (Supplemental EIS). In the plan's name, RMP stands for resource management plan and EIS for environmental impact statement.
One of the 1,120 places the Bureau of Land Management has designated an Area of Critical Environmental Concern. This page shows its line, what BLM found there and what sits inside it.
The line
Ground: USGS The National Map, topographic tiles. Boundaries: BLM's own, read Oct 20, 2026. The 3 grazing allotments below aren't marked.Grazing allotments
3 grazing allotments cover part of this line. Their permittees aren't named here yet.
- Crystal River4,585acres
- Mt Sopris1,837acres
- N Thompson Cr Com677acres
The nearest areas
- Glenwood Springs Debris Flow Hazard Zones ACECColorado · 6,101 acres · at least 3 active mining claims, 18 rights of way, 4 grazing allotments covering part of it16miles
- Deep Creek ACECColorado · 4,422 acres · at least 46 active mining claims, 3 rights of way, 6 grazing allotments covering part of it25miles
- Lyons Gulch ACECColorado · 429 acres · 2 grazing allotments covering part of it28miles
- Grand Hogback ACECColorado · 4,306 acres · 3 rights of way, 3 grazing allotments covering part of it31miles
- Hardscrabble - East Eagle ACECColorado · 4,152 acres · 3 rights of way, 4 grazing allotments covering part of it32miles
More from BLM's Colorado office
Every area BLM's Colorado office holdsThe proposed rule
A proposed rule, RIN 1004-AF53, would change how BLM drafts every land use plan, and how it designates ACECs like Thompson Creek ACEC. The comment window hasn't opened: the proposed rule wasn't in the Federal Register at our last check. The Watch sends one email the day it prints.
The rule's abstract
The purpose of this rulemaking is to establish in regulations an updated process for the approval of the development, revision, amendment, and maintenance of land use plans, as provided for by the Federal Land Policy and Management Act of 1976, for public lands administered by the Bureau of Land Management (BLM). Additionally, this rulemaking will provide clarification of the process the BLM uses for designating Areas of Critical Environmental Concern.Unified Agenda entry for RIN 1004-AF53, Publication ID 2026, reginfo.gov (OMB OIRA), read Oct 18, 2026