Hard Rock Exploration License | Amendment for Sentinel Metals (dba Great Plains Mining LLC) – Columbia Gold – LICENSE NO. 00816 |Final EA and Approval to Proceed
The Montana Department of Environmental Quality (DEQ) accepted public comment from March 20, 2026, through April 13, 2026, on a draft Environmental Assessment (EA) for Sentinel Metals proposed Amendment to an Exploration License under the Metal Mine Reclamation Act, and exploration project near Lincoln, Montana in Lewis and Clark County.
DEQ received 8,736 public comments from 1,713 individuals and corporations on the draft Environmental Assessment (EA). DEQ reviewed all comments and incorporated responses to the comments into the final EA for the proposed exploration project.
Sentinel Metals posted the required reclamation bond and DEQ issued Approval to Proceed for the project. The Exploration License Amendment authorizes 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 are authorized to take place near Lincoln, with up to 1.53 acres of surface disturbance on ground previously disturbed by exploration activities. Proposed surface drilling is authorized to total up to 14,359 feet, may reach a maximum depth of 2,296 feet, and is anticipated to intersect the groundwater table. No new access roads are authorized to be constructed, but operations may include overland travel. Reclamation of the disturbance is required.
DEQ prepared a final EA to disclose the potential environmental impacts from the project and shares its determination of whether there are significant impacts. The final EA is not a decision document but rather is a disclosure of the potential impacts from the project. The proposed project met the requirements set forth in Montana law for exploration activities and a performance bond was submitted by Sentinel and approved and held by the state. DEQ issued the Exploration License Amendment.
To view the final EA, please visit the DEQ website at: https://deq.mt.gov/mining/Programs/hardrock.
Location: Lewis and Clark County (46.948465°, -112.511792°)
Associated Materials:
Final Environmental Assessment (EA) and Approval to Proceed
Tags: MEPA, Public Notice and Hard Rock