Environmental Impact Statement (EIS)
An Environmental Impact Statement (EIS), under United States environmental law, is a document required by the
National Environmental Policy Act for federal government or agency actions "significantly affecting the quality of the human environment." Used as a tool for decision making, an EIS describes the positive and negative environmental effects of proposed agency action as well as alternative actions. Several U.S. state governments have also adopted "little NEPA's," i.e., state laws imposing EIS requirements for particular state actions, such as an Environmental Impact Report (EIR) under the California Environmental Quality Act (CEQA).
An EIS typically has four main sections:
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- An Introduction including a statement of the Purpose and Need of the Proposed Action.
- A Range of Alternatives including, at a minimum, the Proposed Action and No Action Alternative (project would not be authorized), which provides a baseline for analysis. All other reasonable alternatives should be described in this section; however, they do not all have to be analyzed throughout the EIS. If an alternative is eliminated from further analysis within the document, the reason for doing so should be stated in this section.
- A description of the Affected Environment, which typically includes information on resources such as water, soils, vegetation, air quality, public use and recreation, etc.
- An Analysis of the Environmental Effects/Impacts (direct, indirect, and cumulative) of each of the possible alternatives.
An EIS should also include a lists of preparers, agencies, organizations and persons to whom the statement is sent, an index, and appendices (as appropriate).
Environmental Assessment (EA)
Not all federal actions require a full Environmental Impact Statement (EIS) under the National Environmental Policy Act. If the action may or may not cause a significant impact, the agency can prepare a smaller, shorter document called an Environmental Assessment (EA) first. The finding of the EA determines whether an EIS is required. If the EA indicates that no significant impact is likely, then the agency can release a Finding of No Significant Impact (FONSI) and carry on with the proposed action. Otherwise, the agency must then conduct a full-scale EIS. Most EAs result in a FONSI.
An EA is described in Section 1508.9 of the Council's NEPA regulations. Generally, an EA includes brief discussions of the following: the need for the proposal; alternatives (when there is an unresolved conflict concerning alternative uses of available resources); the environmental impacts of the proposed action and alternatives; and a listing of agencies and persons consulted. It is very similar to an EIS, but generally shorter and a little less detailed.