Grassy Mountain Gold

About Grassy

Key Project Details

The Grassy Mountain Gold Project is a proposed underground gold mine located in Malheur County, eastern Oregon, approximately 22 miles south of Vale and 70 miles west of Boise, Idaho.

The project's above-ground site infrastructure in the rolling hills of the high desert region of the western Snake River Plain is a fraction of the total 8,200-acre land package, including three patented (private) lode claims that host the gold deposit, 455 unpatented lode claims, nine mill site claims, and a surface and mineral rights lease.

Paramount Gold owns 100% of the private land containing the gold deposit and controls all associated mining claims within the project area.

Since acquiring the project, the company has significantly expanded and upgraded the mineral resource, improved metallurgical recoveries, and strengthened the project’s overall financial viability.

Key milestones include Malheur County land use approval, issuance of the federal Final Environmental Impact Statement (FEIS), and Record of Decision (ROD), and the release of the draft state permits. The project is now in the final stage of Oregon’s state permitting process, with final permit decision expected in the second half of 2026.

MINING AND PROCESSING OPERATIONS

Grassy Mountain is designed as an underground gold mine. The project is expected to produce approximately 385,800 recoverable ounces of gold and 480,000 recoverable ounces of silver over an estimated initial mine life of 9.3 years, with average annual production of 41,400 ounces of gold and 51,500 ounces of silver.

Ore will be extracted using conventional underground mining methods including drilling, blasting, loading, and hauling. (To learn more about mining methods, please follow this link.) The ore will be transported to the surface for crushing and processing, while waste rock will be placed in a designated Temporary Waste Rock Storage facility.

Gold will be recovered in a carbon-in-leach (CIL) processing plant with a capacity of 750 short tons per day, operating seven days per week. Following processing, the remaining material (tailings) will undergo detoxification before being transferred to the Tailings Storage Facility, where water will be recovered and pumped back into the processing plant.

Surface facilities will include the processing plant, storage areas, roads, utilities, water and power infrastructure, administrative buildings and other supporting site infrastructure.

Key project components

Component	Purpose
The underground mine is where the gold-bearing ore will be extracted through a network of underground tunnels designed to support safe and efficient mining operations.
Portal	Main entrance to the underground mine.
Decline	Gradually sloping tunnel that provides access for workers and equipment to reach the underground workings.
Ventilation shaft	Vertical shaft that provides fresh air throughout the underground mine and removes heat, dust, and exhaust to help maintain a safe working environment.

The processing plant area is where the gold is extracted from the mined ore.
Crushing facilities	Machines that break large rocks into smaller pieces.
Conveyors and ore bins	Belts and containers that move and hold crushed rock.
CIL processing plant	A building where gold is extracted from crushed ore using a chemical process (CIL stands for 'carbon-in-leach').
Reagent storage	Secure storage for the chemicals used in processing.
Gold room	Where the recovered gold is processed into its final form and securely stored.
Collection pond	A lined basin that captures water used in processing.

The Tailings Storage Facility stores the processed rock (tailings) after gold has been extracted.
Embankment	A built-up wall or dam.
Impoundment	The storage area behind the embankment where the tailings are placed.
Reclaim pond	Collects water that can be recycled back into the plant.

The Temporary Waste Rock Storage Facility is a designated area for temporarily storing waste rock that cannot be economically processed.

Site Buildings and Support Facilities:
Main gate and guard house	The controlled entrance to the site.
Administration office and change house	Offices and locker rooms for workers.
Assay laboratory and sample preparation area	A laboratory that tests rock samples to determine how much gold they contain.
Truck shop and warehouse	Where vehicles are repaired and supplies are stored.
Process plant workshop and warehouse	Where processing equipment is maintained and repaired, and where spare parts and tools are stored.
Wash pads	Areas for cleaning equipment.
Explosive magazines	Secure storage for blasting materials.
Parking areas and ore stockpiles	Space for vehicles and temporary rock storage.
Hazardous waste storage	Safe containment for any hazardous solid or liquid materials.
Fuel storage and dispensing area	Where diesel and other fuels are stored and distributed.
Meteorological station	Monitors local weather conditions to support safe operations and environmental management.

Roads and access: Existing Twin Springs and Cow Hollow public roads will be upgraded (not paved), and a new mine access road will connect the site to the public road network. Internal roads will provide access for workers, equipment, and haul trucks to move ore safely around the site.

The water supply will include production wells to pump groundwater, a water pipeline to transport water to the location where it is needed, a potable water treatment plant, and a raw water storage tank that will hold untreated water for industrial use.

The power supply will include a power substation that receives electricity and distributes it across the site, new and upgraded power lines (14.4 kilovolt) bringing power from the grid, and on-site powerlines and generators for internal electrical distribution and backup power.

Stormwater and environmental controls will include:
Stormwater diversion channels	Ditches and channels that manage rainwater and snowmelt to reduce erosion.
Growth media stockpiles	Topsoil and organic material stored for use in reclamation.
Perimeter fencing	Site fencing for safety and security.

Other areas:
Exploration areas	Locations where drilling and sampling will continue for better understanding of the ore deposit.
Septic system	On-site sewage treatment for restrooms and facilities.
Quarry and reclamation borrow areas	Areas where rock and soil are obtained for construction and are later used to help restore the site when mining ends.
Yards and laydown areas	Open spaces used for the temporary storage of equipment and materials during construction and mining operations.

Expected Project Timeline

KEY MILESTONES AND TIMELINE

The timeline below reflects the project’s anticipated sequence of development activities. Actual timing may vary based on permitting processes, regulatory reviews, and other factors.

Key Milestones	Timing	Status
Final Environmental Impact Statement	January 29 2026	Issued
Federal Record of Decision	January 29 2026	Issued
Final State Permits	July-December 2026	Pending
Detailed Engineering	Following receipt of final state permits	Planned
Construction Start	Following completion of detailed engineering	Planned
Construction Completion – Commencement of Production	Following completion of construction	Planned

Last updated: July 2026