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Frequently Asked Questions

BLM State AML Offices | Partnerships | How BLM AML Projects Work | Frequently Asked Questions

What is the objective of the BLM AML program?
The AML program’s overall objective is to support core BLM programs by providing solutions to environmental and physical safety hazards associated with abandoned hardrock mines on or affecting lands administered by BLM.

Hard rock minerals generally include gold, silver, copper, lead, zinc, magnesium, nickel, molybdenum, tungsten, uranium, and selected other minerals.

Why is the AML program important?
The AML program works to eliminate or reduce the dangers to public health, safety, and the environment as a result of impacts related to abandoned hard rock mines on public lands. The AML program supports BLM core programs including Land Use Planning, Water Quality, Fisheries and Wildlife Biology, Recreation, and Hazard Management and Resource Restoration.

What is an abandoned mine?
Abandoned mines generally include a range of mining impacts, or features that may pose a threat to water quality, public safety, and/or the environment. For many abandoned mines, no current claimant of record or viable potentially responsible party exists.

The AML program addresses hardrock mines on or affecting public lands administered by BLM, at which exploration, development, mining, reclamation, maintenance, and inspection of facilities and equipment, and other operations ceased as of January 1, 1981 (the effective date of BLM’s Surface Management regulations codified at 43 CFR 3809) with no intention of resuming active operation.  See more definitions in the AML Glossary.

What are examples of AML hazards?

  • Physical hazards: Unsecured AML sites pose a risk of death or serious injury by falling down open mine shafts.
  • Human health hazards: Exposure to toxic gases and chemicals, cave-ins, explosives, and water hazards endanger human health.
  • Environmental hazards: Water contaminated by mine tailings threatens nearby communities and destroys habitats.

How many abandoned mines are there?
There are 38,892 known sites in the BLM AML database as of 01/10/2013. Approximately twenty to thirty percent of AML sites pose safety hazards, and approximately five to ten percent pose environmental hazards.

In addition, there are an estimated total of 100,000–500,000 AML sites to be fully identified or characterized. Unfortunately, a comprehensive inventory of abandoned mines does not currently exist; however, other Federal agencies including the Forest Service (FS) , the U.S. Environmental Protection Agency (EPA) , the National Park Service (NPS) , the Office of Surface Mining (OSM) , and most mining states and tribes have their own inventories. The Government Accountability Office (GAO) summarized abandoned mine estimates in a report entitled, “Federal Land Management: Information on Efforts to Inventory Hard Rock Mines,” issued in February, 1996 (GAO/RCED-96-30).

  How much will it cost to reclaim the abandoned mines located on the public lands?

Most of the known sites have not been assessed and it is extremely difficult to estimate how long it would take or what the cost would be to address them because of the wide variation in site complexity, mixed-ownership of affected lands, and the need for environmental engineering analyses called for under statutory and regulatory remediation methods. While the BLM does not have a total cost estimate to remediate its entire known inventory, it has developed an estimated range of costs for purposes of reporting environmental disposal liabilities as a part of its financial reports. The "AML Feasibility Study for AML Inventory Validation and Physical Safety Closures" and "AML Inventory Study for BLM-Managed Lands in California, Nevada, and Utah: Site Feature Analysis" reports describe the work and cost estimates for validating, inventorying, and conducting physical safety closures on BLM managed lands.


Where are abandoned mines on lands managed by the BLM located? 
 Abandoned mines are located in western states as follows:

StateNumber of Sites*














New Mexico












*Number of Known Sites as of January 2, 2015

How are cleanup projects selected?
Overall, sites are divided into physical safety and water quality sites, although there can be overlap. Priority watersheds are identified by State government agencies in their Clean Water Act reports provided to the U.S. Environmental Protection Agency. BLM prioritizes sites and projects based on a risk-based approach, and are typically located near high population centers or high-use areas. The AML Program selects cleanup projects through a program-wide collaborative process that occurs once a year.

The selection process includes:

  • Applying risk-based watershed approaches reflecting State government priorities.
  • Using risk-based approach for physical safety hazard sites.
  • Coordinating with State and Federal partners.
  • Planning projects through multi-year AML work plans.
  • Focusing on priority watersheds and high-use areas.
  • Conducting peer review by program leads.

Which types of sites become cleanup priorities?
The decision is made on a site-by-site basis, but typically the following factors are taken into consideration when determining priorities.

For water quality sites:

  • Safety: Pose threats to public health, safety, and the environment;
  • Watershed: Are located within State-designated watersheds;
  • Partnerships: Have cost-effective partnerships available;
  • Cost: Have the potential for cost avoidance/recovery;
  • Water quality: Contain impaired water quality standards;
  • Work status: Are continuing projects;
  • Location: Impact BLM-administered lands.

For physical safety sites:

  • Safety: Death or injury has occurred;
  • Public use: Have high public visitation;
  • Accessibility: Are easily accessible;
  • Population: Are located nearby populated areas;
  • Cost: Have cost-effective partnerships available.

How many abandoned mines has BLM reclaimed?
Since 2000, the AML program has remediated approximately 7,100 physical safety features, 600 AML sites and over 1,000 acres restored.

What are some of the ways BLM addresses hazards at abandoned mine sites?
BLM addresses physical safety hazards associated with abandoned mine sites by:

  • Posting warning signs and fencing off access to dangerous areas;
  • Closing horizontal opening (adits) to keep people out. Where bats are present, BLM uses bat gates that allow them to use the adit for habitat;
  • Closing vertical openings (shafts) either by filling them, or by covering them with little roofs (cupolas); and/or
  • Removing and properly disposing hazards such as mining and milling equipment, oil and chemical drums, and other debris.

BLM addresses environmental hazards associated with abandoned mine sites by:

  • Redirecting stream flow to avoid mine wastes and tailings;
  • Capping mine waste and tailings piles located in and around stream beds, or removing and transporting them to an appropriate repository;
  • Plugging adits to reduce or control flow of metals-laden water;
  • Applying low-cost, low-maintenance water treatment methods; and/or
  • Removing toxic soils impacting groundwater.

How can I report an abandoned mine site?
The first thing you should do is “STAY OUT and STAY ALIVE!” If you come across what appears to be an abandoned mine that has no sign or is not closed up, report what you have encountered to local fire, police, or other rescue authorities. They in turn, will notify the appropriate land management agency to investigate the site.

What else can I do to help?
There is still much AML work to be done. See how you can volunteer through BLM.