The National Environmental Policy Act (NEPA), enacted in 1969, stipulates that an Environmental Impact Assessment (EIA) must be conducted for any Federal projects or projects that may impact public lands. An EIA is a comprehensive study to identify: direct and indirect environmental impacts of the project; possible alternatives to the project; the amount of energy and resources that will be used by the project, including those that will be extracted from the land; mitigation plans for environmental impacts of the project; and the ability of the project operator(s) to preserve historic and cultural quality in the area.

Following review of the EIA by the federal or state agency responsible for overseeing NEPA, two outcomes are possible: either a Finding of No Significant Impact (FONSI) or finding to conduct an Environmental Impact Statement (EIS). If an EIS is required, the government agency must undertake this effort. During the EIS process, the mining company typically works with the government agency to synthesize relevant information. There is also an opportunity for public comment. After the EIS has been finalized, it generally guides any future action on the proposed project.

Figure: The process of determining and advancing in the EIA process.