2013 AML Inventory Project

two people examine a mine shaft with a bat cupola
A cupola built over this shaft at the Skidoo Mine helps to conserve bat habitat. Death Valley National Park, California and Nevada.

NPS photo.


The National Park Service (NPS) conducted a comprehensive inventory and assessment of its Abandoned Mineral Lands (AML) from 2010 through 2013 to address two primary objectives:

  • Categorize high, medium, and low priority mitigation needs for NPS AML features according to human hazard and environmental criteria, and;

  • Estimate the resources needed to address priority issues with NPS AML features.

By addressing these two main objectives, this project demonstrates responsiveness to key issues raised by the Office of the Inspector General (OIG) in its July 2008, OIG Audit Report: Abandoned Mine Lands in the Department of the Interior (DOI 2008). It also responds to the NPS Director's October 2, 2008, memorandum, which, in response to the OIG audit, directed regional and associate directors to update the NPS AML inventory and to identify the funding needed to address priority NPS AML features.

National Park System Units with Abandoned Mineral Lands (2013)

U.S. map with aml locations marked
click on map to view regional summaries

To date (2013), 37,050 AML features have been identified in 133 of the 405 units that make up the National Park System. Approximately 75% of the documented AML features are located in the Pacific West Region's California parks, however, all seven NPS regions have significant AML features and issues. Commodities extracted vary regionally but generally include precious metals, base metals, and industrial minerals in the Alaska, Intermountain, and Pacific West Regions;uranium, oil, and gas in the Intermountain Region;and coal, oil, and gas in the Midwest, Northeast, and Southeast Regions. All regions have sand, gravel, and rock quarries. AML features are vestiges of a time when reclamation was not required by federal and state laws and policies, and many pose serious safety issues and resource impacts. Of the 37,050 features inventoried, 1,799 (4.9%) have already received final remedial action, 3,814 (10.3%) are in need of treatment, and the remainder have been inventoried to assist in fully characterizing each site.

The total estimated cost for remediation of the 3,814 AML features that require action over a 12-year period beginning in 2016 is $141 million. Of these, there are 3,317 features in the high priority category (serious safety hazards and/or environmental/cultural impacts), 232 in the medium priority category (moderate safety hazards and/or environmental/cultural impacts), and 265 that are rated as low priority (minimal safety hazards and/or environmental/cultural impacts, but worthy of corrective action).

2014 AML inventory report cover

2014 Comprehensive Report

In response to a 2008 audit by the Department of Interior Office of the Inspector General, the NPS conducted an on-the-ground inventory and assessment of all AML sites Service-wide, and summarized its findings in a report entitled, Abandoned Mine Lands in the National Park System: Comprehensive Inventory and Assessment, dated September 2014.

thumbnail view of a data table

Inventory by Park and Region

Service-wide summary of AML sites and features as of December 31, 2013.

(Table C-1 from AML I&A Report) [PDF—IRMA Data Store]

mine shaft in the desert

Regional Summaries

Learn about regional differences regarding AML issues.

Continue to regional summaries

Related Links

Last updated: January 12, 2023


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