HYDROGEOLOGIC CONSIDERATIONS IN THE U.S. BUREAU OF LAND MANAGEMENT'S REGULATORY PROCESS FOR CONSIDERING MINING PROPOSALS on FEDERAL PHOSPHATE LEASES IN IDAHO

The Department of the Interior, specifically, the Bureau of Land Management (BLM) is charged by the Mineral Leasing Act (MLA), the Federal Lands Management & Policy Act (FLPMA), and other statutes to regulate phosphate leasing, exploration, mining, and reclamation on lands where the United States owns the mineral estate, regardless of surface ownership. BLM’s regulatory mine & reclamation plan (MRP) review process utilizes the National Environmental Policy Act (NEPA) as the vehicle for federal decision making related to MRP activities proposed to occur on and adjacent to federal leases.

Open pit mining of Permean age phosphatic shale in Idaho poses a potential for and has caused releases of contaminants such as selenium from waste rock and overburden into land, vegetation, and water in and around the mining sites. Over the past decade, these releases have resulted in portions of some watersheds being listed as “impaired” under section 303(d) of the Clean Water Act. Over fifteen historic and active mining sites are now undergoing or have been identified for investigation and remediation of selenium and other contamination under the Comprehensive Environmental Response, Compensation & Liability Act (CERCLA). The contamination problem has been well documented since it was discovered in the late 1990’s.

Since that time, in order to prevent additional impacts, BLM’s review of new phosphate MRP applications has incorporated state-of-the-art geochemical tests of waste rock. Hydrogeologic modeling, including infiltration, fate & transport, and steady-state analysis are then used to predict the nature and extent of possible impacts to water quality. Before a MRP can be approved, applicants are required to incorporate measures into the MRP to reduce or otherwise mitigate predicted impacts to within acceptable limits imposed by clean water statutes.

State and federal agencies charged with overseeing those acts participate in BLM’s NEPA process to provide direction on the nature and extent of predicted impacts that may be acceptable and the amount of any impact reduction that may be necessary for project approval. After BLM's approval of an MRP, additional modeling, changes to mining practices, and implementation of other measures may be necessary to address issues identified by environmental monitoring.