National Environmental Policy Act (NEPA) documents-environmental impact statements and assessments-inform agency decisionmaking and let the public know about anticipated effects of a proposed Federal action. The fundamental purposes and principles of efficient, effective Federal impact statement preparation are set forth in the Council on Environmental Quality'simplementing regulations and guidance that have been in existence for nearly three decades. These implementing regulations stress the need for environmental documents to focus on considerations that are truly useful to decisionmakers and the public.