Understanding AML

weathered mining equipment in the desert
Main Keane Wonder Mill, surrounding equipment, and tramway. Death Valley
National Park, California and Nevada.

NPS photo.



diagram of underground mine

NPS illustration.

AMLs includes “features” and “sites.” AML “features” include old mine structures such as headframes or tramways, mine openings such as shafts and adits; piles of waste rock (unprocessed, sub-grade mined rock), mill tailings (reject materials from mined rock that has been processed to remove the desired commodities), and ore; abandoned and orphaned oil and gas wells; fuel storage tanks; drainage diversions; buildings such as mills and assay shops; and abandoned heavy equipment and tools. A collection of these features occurring within a discrete geographic area is called an AML “site.”

AMLs often pose physical safety hazards for both humans and wildlife, and they can also have adverse effects on natural and cultural resources, as well as values such as viewsheds. On the other hand, AMLs also often contain historic resources, provide habitat for wildlife, and support visitor education and enjoyment.

Managing the physical safety hazards, resource impacts, and contamination problems at abandoned mineral lands is an important, complex, and expensive land management issue. In addition to providing funds for hazard mitigation, feature reclamation and response actions, and site restoration projects, the National Park Service maintains a comprehensive, nationwide inventory of abandoned mineral land sites and features; protects cultural resources and wildlife habitat; and educates park visitors about mining history and safety.



AML—Natural & Cultural Resources


Last updated: December 19, 2022


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