SUPPLEMENTARY INFORMATION:

Stillwater Mining Company has submitted a proposed amendment to its mine plan of operations to the Custer Gallatin National Forest and the Montana Department of Environmental Quality, Mining Bureau. The Stillwater Mine is an active underground platinum group metal mining operation in Stillwater County, Montana. Ongoing operations and proposed operations are located on private lands and National Forest System lands within the Beartooth Ranger District.

Purpose and Need for Action

The purpose of the Forest Service action is to respond to the applicant's proposal to amend its mine plan of operations to expand mining operations on National Forest System lands to support continued mining and development of platinum group metals (which include critical minerals) via underground mining at the Stillwater Mine.

The need for Forest Service action is established by the agency's responsibilities under the Organic ( printed page 35953) Administration Act of 1897 (16 U.S.C. 478, 482, and 551) and the locatable minerals regulations at 36 Code of Federal Regulations (CFR) 228 subpart A. In accordance with 36 CFR 228.5, the Forest Service must analyze and provide timely response to the submittal of a plan of operations. Furthermore, the Forest Service must assess whether the proposed operations will be conducted so as, where feasible, to minimize adverse environmental impacts on national forest surface resources in accordance with 36 CFR 228.8.

Proposed Action

The Stillwater Mine Plan of Operations Amendment 14 project proposes changes to the integrated waste management plan to continue production of platinum group metals via underground mining operations for an additional 36 to 42 years, approximately. Specifically on National Forest System lands, Amendment 14 proposes to expand the footprint of the waste rock storage area, construct new ventilation and water management infrastructure, and relocate or change utilization of existing surface infrastructure such as water management and treatment facilities, ancillary facilities near the mine access portals, growth media stockpiles, and borrow areas. Full buildout of the waste rock storage area would require approximately 30 acres of new disturbance on National Forest System lands, including relocating a portion of Nye Creek into an engineered channel. Existing monitoring, reclamation, and closure plans would be modified to accommodate the changes from expanded operations and extended life of the mine.

Alternatives

Under the no-action alternative, the development of the applicant's mineral resource would be limited to those activities approved under the existing plan of operations. At the current rate of operation, the Stillwater Mine will reach full capacity in 2031. The no-action alternative would directly impact 1,100 jobs and impact production at the principal domestic source of palladium and platinum in the continental United States.

List of Substantive Issues and Expected Impacts

Substantive issues are those that meaningfully inform the consideration of reasonably foreseeable impacts of the proposed action or a decision on the alternative selected for implementation (7 CFR 1b.11(a)(53)). The following preliminary substantive issues are anticipated to be evaluated:

• The riparian area and scenic integrity of Nye Creek may be degraded by diverting the natural stream channel into an engineered channel around the waste rock storage area footprint;
• Continued mining operations and additional construction may impact surface and groundwater quality and quantity; and
• Construction and operation of the expanded waste rock facility may impact the availability of suitable topsoil in meeting final reclamation objectives.

Anticipated Permits and other Authorizations

Stillwater Mining Company is working with the Montana Department of Environmental Quality, the Army Corp of Engineers, and the Environmental Protection Agency to secure necessary permits, including State Mine Operating Permit Amendment, Montana Natural Streambed and Land Preservation Act 310 permit, Federal Clean Water Act section 404 permit, and Short-Term Water Quality Standard for Turbidity 318 and 401 permits. Simultaneously, the Forest Service will consult with the U.S. Fish and Wildlife Service regarding section 7 of the Endangered Species Act.

Comments and the Objection Process

This notice of intent initiates the National Environmental Policy Act (NEPA) process timeline, which guides the development of the environmental impact statement. In this process the Forest Service is requesting comments on potential alternatives and impacts, and identification of any relevant information, studies or analyses of any kind concerning impacts affecting the quality of the human environment. It is important that interested members of the public provide their comments at such times and in such manner that they are useful to the agency's preparation of the environmental impact statement. Therefore, written comments must be provided prior to the close of the comment period and should clearly articulate the commenter's concerns and contentions.

This proposed action is subject to the pre-decisional administrative review process, also known as the objection process at 36 CFR 218, subparts A and B. A proposed rule to amend 36 CFR 218 was published in the Federal Register on February 6, 2026 (91 FR 5387), prior to the initiation of public comment in this notice of intent. This proposed action may be subject to the final rule amending 36 CFR 218 if the final rule takes effect before the objection period occurs for this proposed action. Otherwise, this proposed action will be subject to the pre-decisional administrative review process established prior to the February 2026 proposed rule.

Commenting during any designated opportunities to comment provided by the responsible official will govern eligibility to object under 36 CFR 218 once the environmental impact statement and draft record of decision have been published. Comments received in response to this solicitation, including names and addresses of those who comment, will be part of the public record for this proposed action. Comments submitted anonymously will be accepted and considered; however, they will not be used to establish eligibility for the objection process.

Objections will be accepted only from those who have previously submitted specific written comments regarding the proposed project during any designated opportunity for written public comment in accordance with section 218.5(a). Issues raised in objections must be based on previously submitted timely, specific written comments regarding the proposed project unless based on new information arising after designated opportunities.

Cooperating and Participating Agencies

Montana Department of Environmental Quality, Mining Bureau.

Responsible Official

Custer Gallatin Forest Supervisor.

91 FR 35952