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Montana · Area of Critical Environmental Concern

Elkhorn Mountains

BLM found a wildlife resource, a cultural value, a historic value and a fish resource here, and its plan calls for special management. BLM's records place at least 466 active mining claims (and 3 more BLM lists as Filed) and 24 rights of way inside the line today, and 49 grazing allotments cover part of it. It covers 53,434 acres and was designated April 20, 2009, in the Butte RMP (2009). In the plan's name, RMP stands for resource management plan.

Acres53,434
DesignatedApr 20, 2009Butte RMP (2009)
BLM founda wildlife resource, a cultural value, a historic value and a fish resource
Inside, at least539claims, rights of way and allotments, and 3 more claims BLM lists as Filed

The line

Elkhorn Mountains
Mining claim, 411Claimant withheld by BLM, 55Filed, 3Right of way, 24
Ground: USGS The National Map, topographic tiles. Boundaries: BLM's own, read Oct 20, 2026. 46 marks are where BLM's own maps draw them; 447 claims are placed at the middle of the section, quarter section, quarter-quarter section or survey lot their land description names, not at the stakes on the ground. Hover or tap one for its holder. The 49 grazing allotments below aren't marked.

Who holds the claims

At least 469 claims sit inside this line: 466 active and 3 filed and pending, 414 with a holder BLM names and 55 with a claimant BLM withholds under the Privacy Act. BLM lists 466 as Active and 3 as Filed.

  • GRAYMONT WESTERN US INC394claims
  • Names withheld by BLM (private individuals)55claims
  • ROCKY MOUNTAIN PROSPECTORS LLC15claims
  • MONTANA RECLAIM LLC4claims
  • WESTMARK INTL CORP1claim

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

24 rights of way sit inside the line. BLM files 18 under non-energy facilities, 5 under other energy facilities and 1 under none.

  • BUTTE FIELD OFFICE5rights of way
  • Holder not listed by BLM2rights of way
  • NORTHWESTERN CORPORATION2rights of way
  • USFS (HELENA-LEWIS AND CLARK NATIONAL FOREST)2rights of way
  • NORTHWESTERN ENERGY2rights of way

Grazing allotments

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

  • Allotment USFS-GRZ-10004.01034724,215acres
  • Allotment USFS-GRZ-10241.01034920,065acres
  • Limestone Hills14,304acres
  • Allotment USFS-GRZ-10080.01034713,826acres
  • Boulder River12,832acres

The nearest areas

More from BLM's Montana/Dakotas office

Every area BLM's Montana/Dakotas 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 Elkhorn Mountains. 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