The purpose of an EA is to determine the significance of the environmental effects and to look at alternative means to achieve the agency's objectives. The EA is intended to be a concise document that (1) briefly provides sufficient evidence and analysis for determining whether to prepare an EIS; (2) aids an agency's compliance with NEPA when no environmental impact statement is necessary; and (3) facilitates preparation of an Environmental Impact Statement when one is necessary.
Sources: Council on Environmental Quality, Executive Office. 2007. Citizens Guide to NEPA. Accessed on 9 September 2013. Available at http://www.frames.gov