Announcement • May 27
Silver Bow Mining Receives Authorization to Proceed from Montana DEQ for Expanded Rainbow Block Exploration Program
Silver Bow Mining Corp. announced that the Montana Department of Environmental Quality issued Silver Bow Mining an Authorization to Proceed for Amendment 2 to Exploration License No. 00857 at the Rainbow Block project in Butte, Montana. Silver Bow Mining is fully authorized to conduct all surface and underground exploration activities outlined in its approved Plan of Operations. MT DEQ dated the Authorization to Proceed effective May 18, 2026, following the Company's satisfaction of all regulatory conditions, including the posting of a $2,188,039 surety bond for anticipated reclamation costs and MT DEQ's finalization of a Final Environmental Assessment on May 8, 2026. Amendment 2 expands the scope of authorized exploration at the Rainbow Block, allowing both surface and underground work to further define and improve geological understanding of the deposit. Surface drilling at the Rainbow Block is already underway as announced in the Company's news release dated May 4, 2026. MT DEQ authorized Amendment 1 to Exploration License No. 00857 on October 4, 2021, and the Company has been drilling at the Missoula and Badger sites under that authorization. Amendment 2 adds seven new surface drill pad locations with significantly greater depth and footage and authorizes development of the Rainbow Decline which consists of a new portal and approximately 6,000 feet of underground development connecting to the existing Lexington Tunnel level. Highlights of Authorized Amendment 2 Activities include Rainbow Decline - Underground Development: Construct one new portal with an opening of 16 feet by 15 feet and develop approximately 6,000 feet of underground workings connecting to the existing Lexington Mine shaft at the 400-foot level. Surface Drilling: Construct up to seven new drill pads and drill up to 53 surface core holes totaling approximately 102,000 feet, with individual holes reaching depths of up to 7,000 feet. Underground Drilling: Conduct underground drilling from within the Rainbow Decline to support mineral resource definition. Bulk Sampling: Stockpile up to 10,000 tons of mineralized material for bulk metallurgical testing. Development Rock: Excavate and stockpile up to 150,000 cubic yards of development rock in five surface stockpiles. Project Area: Disturb up to approximately 11.95 acres, all on previously disturbed private land in Walkerville and Butte, Montana. Timeline: Complete all exploration activities by December 31, 2029, with reclamation completed no later than December 31, 2031. Bond Posted: Surety bond of $2,188,039 posted with and accepted by MT DEQ, satisfying the reclamation bond requirement under Section 82-4-332(3), Montana Code Annotated. The Authorization to Proceed follows a series of significant milestones at Silver Bow Mining. On April 30, 2026, the Company completed its initial public offering on the NYSE American, with common shares trading under the symbol SBMT. On May 4, 2026, the Company announced the commencement of surface drilling at the Rainbow Block under Amendment 1, a program expected to include approximately 25,000 feet of drilling. On May 12, 2026, the Company announced a contract with MES Mining, a division of Mining & Environmental Services LLC, for rehabilitation and modernization of the existing Chief Joseph portal and underground decline under Amendment 1. MES is now mobilizing equipment and materials to Butte, with rehabilitation work anticipated to commence in June. The Amendment 2 Authorization to Proceed expands the authorized scope of work at the Rainbow Block to encompass the full surface and underground exploration program the Company intends to advance. Information generated through Amendment 2 activities is expected to support continued geological modeling, metallurgical testing, engineering studies, and future project evaluation. Silver Bow Mining submitted a complete application for Amendment 2 on October 20, 2025. MT DEQ conducted a full environmental review under the Montana Environmental Policy Act and the Metal Mine Reclamation Act, issuing the Final Environmental Assessment on May 8, 2026. DEQ selected the Company's Proposed Action Alternative and determined that an Environmental Impact Statement was not required. Following the Company's satisfaction of all remaining conditions, MT DEQ issued the Authorization to Proceed on May 18, 2026. The Rainbow Block project is an exploration-stage project, and the Company has not established mineral reserves or demonstrated economic viability.
