Environmental impact statement
An environmental impact statement (EIS), under United States environmental law, is a document required by the 1969 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. Preliminary versions of these documents are officially known as a draft environmental impact statement (DEIS) or draft environmental impact report (DEIR). Purpose. 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. In particular, an EIS acts as an enforcement mechanism to ensure that the federal government adheres to the goals and policies outlined in the NEPA. An EIS should be created in a timely manner as soon as the agency is planning development or is presented with a proposal for development. The statement should use an interdisciplinary approach so that it accurately assesses both the physical and social impacts  of the proposed development. In many instances an action may be deemed subject to NEPA's EIS requirement even though the action is not specifically sponsored by a federal agency. These factors may include actions that receive federal funding, federal licensing or authorization, or that are subject to federal control. Not all federal actions require a full EIS. If the action may or may not cause a significant impact, the agency can first prepare a smaller, shorter document called an Environmental Assessment (EA). 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. A limited number of federal actions may avoid the EA and EIS requirements under NEPA if they meet the criteria for a categorical exclusion (CATEX). A CATEX is usually permitted when a course of action is identical or very similar to a past course of action and the impacts on the environment from the previous action can be assumed for the  proposed action, or for building a structure within the footprint of an existing, larger facility or complex. For example, two recently completed sections of Interstate 69 in Kentucky were granted a CATEX from NEPA requirements as these portions of I-69 utilize existing freeways that required little more than minor spot improvements and a change of highway signage. Additionally, a CATEX can be issued during an emergency when time does not permit the preparation of an EA or EIS. An example of the latter is when the Federal Highway Administration issued a CATEX to construct the replacement bridge in the wake  of the I-35W Mississippi River Bridge Collapse. NEPA does not prohibit the federal government or its licensees/permittees from harming the environment, instead it requires that the prospective impacts be understood and disclosed in advance. The intent of NEPA is to help key decisionmakers and stakeholders balance the need to implement an action with its impacts on the surrounding human and natural environment, and provide opportunities for mitigating those impacts while keeping the cost and schedule for implementing the action under control. However, many activities require various federal permits to comply with other environmental legislation, such as the Clean Air  Act, the Clean Water Act, Endangered Species Act and Section 4(f) of the Federal Highway Act to name a few. Similarly, many states and local jurisdictions have enacted environmental laws and ordinances, requiring additional state and local permits before the action can proceed. Obtaining these permits typically requires the lead agency to implement the Least Environmentally Damaging Practicable Alternative (LEDPA) to comply with federal, state, and local environmental laws that are ancillary to NEPA. In some instances, the result of NEPA analysis leads to abandonment or cancellation of the proposed action, particularly when the "No Action" alternative ends up being  the LEDPA. Layout. An EIS typically has four sections: While not required in the EIS, the following subjects may be included as part of the EIS or as separate documents based on agency policy. Every EIS is required to analyze a No Action Alternative, in addition to the range of alternatives presented for study. The No Action Alternative identifies the expected environmental impacts in the future if existing conditions were left as is with no action taken by the lead agency. Analysis of the No Action Alternative is used to establish a baseline upon which to compare the proposed "Action  alternatives. Contrary to popular belief, the No Action Alternative" doesn't necessarily mean that nothing will occur if that option is selected in the Record of Decision. For example, the "No Action Alternative" was selected for the I-69/Trans-Texas Corridor Tier-I Environmental Impact Statement. In that Record of Decision, the Texas Department of Transportation opted not to proceed with building its portion of I-69 as one of the Trans-Texas Corridors to be built as a new-terrain route (the Trans-Texas Corridor concept was ultimately scrapped entirely), but instead decided to proceed with converting existing US routes  to I-69 by upgrading those roads to interstate standards. NEPA process. The NEPA process is designed to involve the public and gather the best available information in a single place so that decision makers can be fully informed when they make their choices. This is the process of EIS "Environmental Impact Statement" Often, the agencies responsible for preparing an EA or EIS do not compile the document directly, but outsource this work to private-sector consulting firms with expertise in the proposed action and its anticipated effects on the environment. Because of the intense level of detail required in analyzing  the alternatives presented in an EIS or EA, such documents may take years or even decades to compile, and often compose of multiple volumes that can be thousands to tens of thousands of pages in length. To avoid potential conflicts in securing required permits and approvals after the ROD is issued, the lead agency will often coordinate with stakeholders at all levels, and resolve any conflicts to the greatest extent possible during the EIS process. Proceeding in this fashion helps avoid interagency conflicts and potential lawsuits after the lead agency reaches its decision. Tiering. On exceptionally large projects, especially proposed  highway and railroad corridors that cross long distances, the lead agency may use a two-tiered process prior to implementing the proposed action. In such cases, the Tier I EIS would analyze the potential socio-environmental impacts along a general corridor, but would not identify the exact location of where the action would occur. A Tier I ROD would be issued approving the general area where the action would be implemented. Following the Tier I ROD, the approved Tier I area is further broken down into subareas, and a Tier II EIS is then prepared for each subarea, that identifies  the exact location of where the proposed action will take place. The preparation of Tier II EISs for each subarea proceeds at its own pace, independent from the other subareas within the Tier I area. For example, parts of the proposed Interstate 69 extension in Indiana and Texas, as well as portions of the Interstate 11 corridor in Nevada and Arizona are being studied through a two-tiered process Strengths. By requiring agencies to complete an EIS, the act encourages them to consider the environmental costs of a project and introduces new information into the decision-making process. The NEPA  has increased the influence of environmental analysts and agencies in the federal government by increasing their involvement in the development process. Because an EIS requires expert skill and knowledge, agencies must hire environmental analysts. Unlike agencies who may have other priorities, analysts are often sympathetic to environmental issues. In addition, this feature introduces scientific procedures into the political process. Limitations. The differences that exist between science and politics limit the accuracy of an EIS. Although analysts are members of the scientific community, they are affected by the political atmosphere. Analysts do not have the luxury of an unlimited time for  research. They are also affected by the different motives behind the research of the EIS and by different perspectives of what constitutes a good analysis. In addition, government officials do not want to reveal an environmental problem from within their own agency. Citizens often misunderstand the environmental assessment process. The public does not realize that the process is only meant to gather information relevant to the decision. Even if the statement predicts negative impacts of the project, decision makers can still proceed with the proposal.