<P> An environmental impact statement (EIS), under United States environmental law, is a document required by the National Environmental Policy Act (NEPA) for certain actions "significantly affecting the quality of the human environment". An EIS is a tool for decision making . It describes the positive and negative environmental effects of a proposed action, and it usually also lists one or more alternative actions that may be chosen instead of the action described in the EIS . Several U.S. state governments require that a document similar to an EIS be submitted to the state for certain actions . For example, in California, an Environmental Impact Report (EIR) must be submitted to the state for certain actions, as described in the California Environmental Quality Act (CEQA). One of the primary authors of the act is Lynton K. Caldwell . </P> <P> The purpose of the NEPA is to promote informed decision - making by federal agencies by making "detailed information concerning significant environmental impacts" available to both agency leaders and the public . The NEPA was the first piece of legislation that created a comprehensive method to assess potential and existing environmental risks at once . It also encourages communication and cooperation between all the actors involved in environmental decisions, including government officials, private businesses, and citizens . </P>

When must an environmental impact statement be prepared and what must it include
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