DEQ Requests Public Comment on Draft Environmental Assessment for Exploration Project Near Lincoln

• Madison McGeffers
• March 20 2026 The Montana Department of Environmental Quality (DEQ) is requesting public comment on a draft Environmental Assessment (EA) for a proposed exploration project near Lincoln, in Lewis and Clark County pursuant to the Montana Environmental Policy Act (MEPA). The draft EA is specific to an exploration project proposed by Sentinel Metals (Sentinel), doing business as Great Plains Mining, LLC.

Exploration is a distinct activity from mining and is intended to collect data and characterize commercial potential of an ore body for possible mining. Sentinel submitted a complete exploration license amendment application with the final supplemental documents received by DEQ on March 9, 2026. In the application, Sentinel proposes collection of subsurface geological information through core drilling to characterize mineralization at the Columbia Gold Project area, building on prior exploration conducted in 2016.

The exploration activities would take place near Lincoln, with up to 1.53 acres of surface disturbance on ground previously disturbed by exploration activities. Proposed surface drilling would total up to 14,359 feet, would reach a maximum depth of 2,296 feet, and is anticipated to intersect the groundwater table. No new access roads would be constructed, but operations would include overland travel. Reclamation of the disturbance would be required. Sentinel proposes that exploration operations would commence upon DEQ’s acceptance of the required reclamation bond and DEQ’s issuance of final approval for the project.

In the draft EA, DEQ discloses the potential environmental impacts from the project and shares its determination of whether there are significant impacts. The draft EA is not a decision document but rather is a disclosure of the potential impacts from the project. If a proposed project meets the requirements set forth in Montana law for exploration activities and a performance bond is submitted by Sentinel and approved and held by the state, then DEQ must issue the Exploration License Amendment.

To submit public comment or view the draft EA, please visit the DEQ website. DEQ will accept public comments on the draft EA through April 6, 2026.

References and links in this press release may not work once public comment periods and documents are no longer active. Please submit an information request if you are looking for documents that are not available through the DEQ website.

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