Abandoned Hardrock Mines: Land Management Agencies Should Improve Reporting of Total Cleanup Costs

What GAO Found

The U.S. Departments of the Interior (Interior) and Agriculture (USDA) spent approximately $109 million and $10 million, respectively, from fiscal years 2017 through 2021, to clean up contamination at abandoned hardrock mines on the lands they manage. Both agencies said they have more abandoned hardrock mines than funds to clean them up.

Molybdenum Mine Cleanup on Federal and Private Lands in New Mexico

Note: Molybdenum is a hardrock mineral used in the production of steel and other materials.

Interior and USDA included certain estimated costs for cleaning up abandoned hardrock mines in their financial statements, consistent with federal accounting standards. However, while not required to do so by the accounting standards, the agencies did not clearly identify which costs were specific to abandoned hardrock mines. Further, Interior and USDA budget materials did not communicate known information about implicit exposures related to abandoned hardrock mines—cleanup costs where there is an expectation that the government will provide assistance beyond the legally required amount. GAO's work on fiscal exposures demonstrates the importance of agencies providing decision makers with a comprehensive picture of the federal government's future financial obligations. Without Interior and USDA clearly communicating specific information on known potential future cleanup costs for abandoned hardrock mines, decision makers may not be able to make fully informed cleanup decisions.

Interior has taken some steps to implement the abandoned hardrock mine land program established under the Infrastructure and Investment Jobs Act to conduct certain activities, including inventory and cleanup, on mines on federal land, and provide grants for those activities to states and tribes with jurisdiction over abandoned hardrock mine land. For example, in collaboration with federal and nonfederal partners, Interior has begun developing a national inventory of mines and has drafted high-level goals and objectives for the program. As Interior continues building the program, it could benefit from developing performance measures—as described in leading practices for program management—to help officials fully assess progress toward achieving its goals and objectives.

Why GAO Did This Study

There are at least 22,500 known abandoned hardrock mine features—e.g., pits or tunnels—on federal lands. They pose risks to human health and the environment because they can leak toxic chemicals, such as arsenic, into nearby waterways.

Interior and USDA may pay for the cleanup of abandoned mine contamination on federal lands if no viable potentially responsible party is identified. Federal accounting standards direct agencies to estimate and report certain future cleanup costs in their financial statements.

GAO was asked to provide information about agency cleanup of abandoned hardrock mines. This report describes (1) what Interior and USDA have spent to clean up environmental contamination at abandoned hardrock mines from fiscal years 2017 through 2021; (2) the extent to which agencies communicated estimated cleanup costs; and (3) Interior's steps to implement the abandoned hardrock mine land program, and the extent to which Interior followed leading practices for program management.

GAO reviewed federal accounting standards, laws, regulations, and agency documents; analyzed mine cleanup expenditure and cost estimation data; and interviewed agency officials.