Golden Sunlight Mine Montana: Reclamation Status

The Golden Sunlight gold mine near Whitehall, Montana, no longer mines new ore. Surface mining ended in 2015 and underground mining stopped in April 2019, according to the state environmental impact statement. Tailings reprocessing continues, with deposition now expected to end around 2038 (DEQ). The site is in a long reclamation phase: the Montana Department of Environmental Quality (DEQ) held a reclamation bond of US$138.7 million on the permit at the time of its 2026 bond notice, and about 1,256 of 2,576 disturbed acres had been reclaimed by May 2021. This guide pulls the figures from DEQ documents so consultants, lenders and neighbours can see what is done, what is still open and what to check next.

Golden Sunlight Mine Montana at a glance

The table gives the main facts, each with the document it comes from. Terms: a tailings storage facility (TSF) is the impoundment that holds the fine waste left after gold is extracted from crushed ore; a reclamation bond is money or a surety the operator posts so the state can finish cleanup if the operator cannot.

From open pit to reprocessing: how the site got here

DEQ’s predecessor, the Department of State Lands, approved the operating permit on 27 June 1975, and the Bureau of Land Management approved the plan of operations in 1982 (DEQ final EIS, 2021). Barrick Gold Corporation described the mine as having produced more than 3 million ounces of gold over nearly 40 years before it shut down in 2019, and said it owned the site when it announced the closure project in March 2021.

Gold in this district sits in sulfide-bearing rock. That matters for cleanup, because tailings that still contain sulfide minerals such as pyrite can turn acidic when exposed to air and water. The EIS gives the sulfide content of the older tailings in TSF-1 as about 4 percent on average, with a target of 0.5 percent after reprocessing.

Two older decisions shaped everything after. In 1998 four environmental groups sued DEQ over a plan to reclaim the pit only in part, and a district judge ruled that the state had based the plan on the operator’s finances rather than the constitutional duty to reclaim, as reported by High Country News. The same year voters passed a ban on new cyanide open-pit heap-leach and vat-leach gold mines. Both are covered in the law section below.

How much of the Golden Sunlight land has been reclaimed

DEQ counted 2,576 disturbed acres inside a 3,399-acre permitted disturbance limit in May 2021, of which 1,256 acres had been covered with topsoil and seeded (final EIS, Chapter 2). Reclaimed acres are measured in plan view, meaning as seen from above, not along the slope. The waste rock dumps are the largest single feature: about 1,305 acres in total, with the West dump complex at about 479 acres and the East complex at about 455 acres.

Chart

Permit area, disturbance and reclaimed land

Acres, as of May 2021

The 2026 bond notice adds a newer data point. The operator asked for a partial bond release after finishing grading and soil placement across roughly 525 acres over the previous five years. DEQ noted that most of those areas had also been recently seeded, but it is keeping bond for seeding and weed control until the plants are fully established and stable.

Two limits apply when reading these numbers. They are operator and DEQ reports, not independent field surveys, and “reclaimed” in a bond file means the work is done, not that the vegetation has met the final success standard. A satellite vegetation time series can show whether cover is building year after year, which is a useful extra check before a site visit.

Tailings reprocessing and pit backfill: what DEQ approved

The operator applied in 2020 to reprocess tailings, and DEQ issued its Record of Decision on 13 September 2021. The approved Modified Alternative lets the company excavate tailings from TSF-1, re-pulp them, run them through a flotation plant in the existing mill, and place the cleaned residue in the open pit. DEQ said about 26 million tons would be reprocessed, that the work could extend the life of the mine by up to 12 years (DEQ’s 2025 assessment says the updated schedule is 16 years, with tailings deposition ending around 2038) and that all activity stays inside the existing permitted boundary.

The EIS gives the process detail. The flotation plant was sized for about 6,400 tons of tailings per day. It produces a concentrate of residual fine gold and pyrite, with an expected sulfide content of about 42 percent, which is trucked to Barrick mines in Nevada. Taking sulfide out of the tailings before they go back in the ground lowers the chance of acid generation. The finished tailings surface in the pit would sit at 5,173 feet, about 650 feet above the pit bottom, and would cover roughly 50 acres with no permanent ponding.

Local news coverage at the time noted that the operator had closed the mine in 2019 and that DEQ expected reprocessing to run inside the existing footprint, per Montana Public Radio.

Water at the mine: pumpback wells, pit dewatering and treatment

Water is the main long-term issue at a sulfide gold mine in a dry climate. The EIS puts average precipitation at about 13 inches a year, with evaporation from the pit surface estimated at about 30 inches. Groundwater reaches the pit mostly through faults and fractures.

Chart

Groundwater pumpback below the old tailings facility

Gallons per minute; the 1983 figure is reported as over 350

Groundwater downgradient of TSF-1 has been intercepted since 1983, after a clay slurry wall failed when mining began. The pumping rate for those pumpback systems fell from over 350 gallons per minute (gpm) in 1983 to about 40 gpm by 2021. In 2020 the site routed roughly 218 gpm of pit dewatering, rain and seepage-capture water to TSF-2, a 326-acre lined impoundment that began receiving tailings in 1994 and is now managed through natural and forced evaporation.

More recent documents show the system was under strain. DEQ’s April 2025 environmental assessment says the South Well that dewaters the pit stopped working in late February 2024 after fine sediment from tailings built up in it (DEQ traces earlier setbacks to the 2021-2022 commissioning of the reprocessing plant, and issued a warning letter on 31 July 2024), and that the pit water level rose from 4,592 feet in February 2024 to 4,701 feet in January 2025. The assessment also records lime treatment to hold the pH of the tailings discharge in the pit at 9 or higher, and says hydrologic separation between the tailings pool and groundwater was achieved in December 2023.

DEQ approved a replacement dewatering well (Amendment 018) on 2 April 2025. The decision notice sets a new groundwater control elevation of 4,850 feet instead of 4,750 feet, to keep the water in the pit area from flowing out and degrading downgradient groundwater. The 2021 EIS called for a long-term water treatment plant to be built before about 2028. DEQ’s 2025 assessment says long-term water treatment would be done as necessary and moves the end of reprocessing to about 2038, so we found no current construction date for the plant.

▶ The seven environmental impacts of mining, explained in clay. · 2:31

Reclamation bond: what it covers and what changed

Montana law sets a floor of US$200 for each acre of disturbed land and says the bond may not be less than the state’s estimated cost of compliance, including running the site if the operator walks away. DEQ must review each bond annually and do a comprehensive review at least every five years (section 82-4-338, MCA).

Chart

Reclamation bond under permit 00065

US$ million: held, required after work done, proposed after review

For permit 00065, the legal notice with a 22 June 2026 comment deadline sets out the numbers. DEQ holds US$138,668,184. Finished grading and soil work would cut the required bond by US$23,388,365, to US$115,279,819. The five-year review would add US$20,958,171, mostly from higher fuel prices, equipment rates, the cost of removing nonmobile equipment and indirect costs. The net result is a release of US$2,430,194, leaving US$136,237,990. DEQ said it would issue a final determination after the comment period; we found no published final determination as of 16 October 2026.

A bond is not a cost forecast for the whole closure. It covers the costs of work DEQ judges reasonably foreseeable, and at this site it supports water management as well as seeding. Dividing the bond by acres therefore gives a rough yardstick only. The calculator below lets you test your own numbers.

Montana law behind the reclamation requirements

High Country News reported that the 1998 lawsuit ended with a court ruling that the state violated the Montana Constitution’s requirement that mined lands be reclaimed, and the judge ordered a more extensive reclamation plan (High Country News, April 2000).

Montana voters approved initiative CI-137 in November 1998, which bans new open-pit gold and silver mines that use cyanide heap or vat leaching. A 1999 amendment let mines already operating on 3 November 1998 continue under their permits, and the legislative staff memo notes that this effectively allowed Golden Sunlight to keep using cyanide in future expansions. The ban therefore does not stop reprocessing work at this site, but it does stop a new mine of the same type from starting elsewhere in the state.

The Metal Mine Reclamation Act is the main state law for hard rock permits, bonding and closure. Federal land adds the Bureau of Land Management; the EIS notes that a small 1.4-acre area of public land would be covered by tailings in the pit and that the operator needs BLM approval before disturbing it. For a wider view of Montana gold permits and fees, see our guide to gold mining in Montana: permits, fees and satellite targets.

How consultants can check a reclamation site

A desk review of a closed or closing gold mine can be done in a few steps, using public documents first and imagery second.

1. Find the permit file. Search DEQ’s hard rock mining pages for the operating permit number. The environmental reviews and legal notices list amendments, bond figures and dates.
2. Build the acreage table. Copy disturbed, reclaimed and bonded acres from the latest EIS or bond notice. Note the date and the unit (plan view or slope).
3. Read the water section first. Look for control elevations, pumping rates, treatment plans and warning letters, because water drives the cost of closing a sulfide mine.
4. Compare the bond with the work left. Check how much of the bond is for seeding and grading and how much is for water treatment and equipment removal.
5. Check vegetation from space. Sentinel-2 imagery is available every few days and shows whether reclaimed areas are greening over several growing seasons. It does not replace a soil or water test.
6. Visit with permission. Mine land can be private or federal. Get written access, wear safety gear and never enter pits, adits or tailings without the operator’s escort.

Farmonaut builds satellite maps of mining areas from a boundary file, which can feed steps 2 and 5. For the technology side of this site, see our separate post on innovations at the mine, read how satellite-based mineral detection works, or request a quote for your site or contact the team. Satellite results are screening information, not an environmental clearance. Buyers of closed-mine land should also read our due diligence checklist for a gold mine for sale.

▶ What Farmonaut Mining Pro is and how a boundary becomes a satellite map. · 4:56

Related reading on this site: Berkeley Pit Butte Montana: Water Level and Status.

We cover a connected topic in Mine Land Restoration: 7 Steps, Bonds and Timelines.

Frequently asked questions

Is the Golden Sunlight Mine in Montana still operating?

Ore mining has stopped: surface mining ended in 2015 and underground mining in April 2019. The permit remains active for reclamation, water management and the approved tailings reprocessing, and DEQ’s 2026 notice still describes the permittee as authorized to operate a gold mine, mill and tailings reprocessing facilities under permit 00065 (DEQ notice).

Where is the Golden Sunlight Mine?

It is about 5 miles northeast of Whitehall in Jefferson County, southwest Montana, in the Bull Mountains, according to the DEQ bond notice and High Country News.

Who owns the Golden Sunlight Mine?

The permittee is Golden Sunlight Mines, Inc. Barrick Gold Corporation stated in March 2021 that it owned the mine, and DEQ’s 2025 decision notice was addressed to the company’s sustainability manager at a Barrick email address.

How much gold did the mine produce?

Barrick said it produced more than 3 million ounces of gold over nearly 40 years of operation.

How big is the reclamation bond?

DEQ held US$138,668,184 at the time of the 2026 notice and proposed a net release of US$2,430,194, which would leave US$136,237,990.

What is being reprocessed at the site?

Tailings from TSF-1, about 26 million tons, are run through a flotation plant to remove residual gold and pyrite, then the cleaned material is placed in the pit under DEQ’s 2021 decision.

Is there acid mine drainage at Golden Sunlight?

The EIS identifies acidity in water at the base of the pit and describes partial backfill as a way to reduce it. DEQ’s 2025 assessment records lime treatment of the tailings discharge in the pit. Read the permit file and monitoring reports for current water quality data.

Can the public comment on bond changes?

Yes. Montana law requires DEQ to give the public a chance to comment, and to hold a hearing if one is requested, before it releases or reduces a reclamation bond. The 2026 notice set a comment deadline of 22 June 2026.

Can I visit or prospect on the site?

Most of the permit area is private land with active site controls, and a small part is public land under BLM rules. Do not enter without written permission. Pits, tailings and water-handling areas are hazardous.

How can satellites help check reclamation?

Imagery can show vegetation cover and bare ground over time and help plan field checks. It cannot measure soil chemistry or water quality, so it supports, rather than replaces, DEQ monitoring data.