The National Environmental Policy Act (NEPA) directs federal agencies to assess the potential environmental effects of their proposed major actions significantly affecting the human environment and inform the public about those potential effects.

For certain EPA actions, if the effects are likely to be significant, EPA prepares an environmental impact statement (EIS). EPA solicits participation of the tribal government as a “cooperating agency” when the project’s effects may affect Indian country and other tribal areas.

Activities in Indian country and in other tribal areas often require a greater level of NEPA involvement than the same activities in non-tribal areas when these activities occur on tribal lands held in trust by the federal government. The Department of Interior, Bureau of Indian Affairs is the cognizant entity for NEPA in Indian country.