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Colorado · Area of Critical Environmental Concern

San Miguel River ACEC

BLM found a natural system, a wildlife resource and a scenic value here, and its plan calls for special management. BLM's records place at least 16 active mining claims (and 1 more BLM lists as Under Review) and 12 rights of way inside the line today, and 16 grazing allotments cover part of it. It covers 21,657 acres and was designated April 2, 2020, in the 2020 Uncompahgre RMP. In the plan's name, RMP stands for resource management plan.

Acres21,657
DesignatedApr 2, 20202020 Uncompahgre RMP
BLM founda natural system, a wildlife resource and a scenic valueand found it important
Inside, at least44claims, rights of way and allotments, and 1 more claim BLM lists as Under Review

The line

San Miguel River ACEC
Mining claim, 1Claimant withheld by BLM, 15Under Review, claimant withheld, 1Right of way, 12
Ground: USGS The National Map, topographic tiles. Boundaries: BLM's own, read Oct 20, 2026. 21 marks are where BLM's own maps draw them; 8 claims are placed at the middle of the section their land description names, not at the stakes on the ground. Hover or tap one for its holder. The 16 grazing allotments below aren't marked.

Who holds the claims

At least 17 claims sit inside this line: 16 active and 1 filed and pending, 1 with a holder BLM names and 16 with a claimant BLM withholds under the Privacy Act. BLM lists 16 as Active and 1 as Under Review.

  • Names withheld by BLM (private individuals)16claims
  • SHANNA GOLD 6 LLC1claim

BLM's mining rules list designated ACECs among the places where mining that disturbs the surface beyond casual use needs a plan of operations BLM approves. Exploration of five acres or less can go ahead on a notice instead.

The rights of way

12 rights of way sit inside the line. BLM files 8 under non-energy facilities, 2 under oil & gas facilities and 2 under other energy facilities.

  • CO DEPT OF TRANS3rights of way
  • ROCKY MOUNTAIN NATURAL GAS LLC2rights of way
  • CENTURYTEL OF EAGLE INC, D/B/A CENTURYLINK1right of way
  • BEAVER MESA LLLP1right of way
  • QWEST CORPORATION D/B/A CENTURYLINK QC1right of way

Grazing allotments

16 grazing allotments cover part of this line. Their permittees aren't named here yet.

  • Allotment USFS-GRZ-10421.01043118,623acres
  • Allotment USFS-GRZ-10413.01043113,300acres
  • Allotment USFS-GRZ-10407.01043111,204acres
  • Allotment USFS-GRZ-10419.0104318,624acres
  • Dry Park4,727acres

The nearest areas

More from BLM's Colorado office

Every area BLM's Colorado office holds

The proposed rule

A proposed rule, RIN 1004-AF53, would change how BLM drafts every land use plan, and how it designates ACECs like San Miguel River 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

Watch the ruleWhere the rule stands