Under NEPA, federal agencies generally are to evaluate the likely environmental effects of projects they are proposing by preparing either an Environmental Assessment (EA) or a more detailed Environmental Impact Statement (EIS), assuming no Categorical Exclusion (CE) applies. Agencies may prepare an EA to determine whether a proposed project is expected to have a potentially significant impact on the human environment. If prior to or during the development of an EA, the agency determines that the project may cause significant environmental impacts, an EIS should be prepared. However, if the agency, in its EA, determines there are no significant impacts from the proposed project or action, then it is to prepare a document—a Finding of No Significant Impact—that presents the reasons why the agency has concluded that no significant environmental impacts will occur if the project is implemented. An EIS is a more detailed statement than an EA, and NEPA implementing regulations specify requirements and procedures—such as providing the public with an opportunity to comment on the draft document—applicable to the EIS process that are not mandated for EAs. If a proposed project fits within a category of activities that an agency has already determined normally does not have the potential for significant environmental impacts—a CE—and the agency has established that category of activities in its NEPA implementing procedures, then it generally need not prepare an EA or EIS. The agency may instead approve projects that fit within the relevant category by using one of its established CEs. For example, the Bureau of Land Management (BLM) within the Department of the Interior (Interior) has CEs in place for numerous types of activities, such as constructing nesting platforms for wild birds and constructing snow fences for safety. For a project to be approved using a CE, the agency must determine whether any extraordinary circumstances exist in which a normally excluded action may have a significant effect. Figure 1 illustrates the general process for implementing NEPA requirements. Private individuals or companies may become involved in the NEPA process when a project they are developing needs a permit or other authorization from a federal agency to proceed, such as when the project involves federal land. For example, a company may apply for such a permit in constructing a pipeline crossing federal lands; in that case, the agency that is being asked to issue the permit must evaluate the potential environmental effects of constructing the pipeline under NEPA. The private company or developer may in some cases provide environmental analyses and documentation or enter into an agreement with an agency to pay a contractor for the preparation of environmental analyses and documents, but the agency remains ultimately responsible for the scope and content of the analyses under NEPA. The Council on Environmental Quality (CEQ) within the Executive Office of the President oversees the implementation of NEPA, reviews and approves federal agency NEPA procedures, and issues regulations and guidance documents that govern and guide federal agencies’ interpretation and implementation of NEPA. The Environmental Protection Agency (EPA) also plays two key roles in other agencies’ NEPA processes. First, EPA reviews and publicly comments on the adequacy of each draft EIS and the environmental impacts of the proposed actions reviewed in the EIS. If EPA determines that the action is environmentally unsatisfactory, it is required by law to refer the matter to CEQ. Second, EPA maintains a national EIS filing system. Federal entities must publish in the Federal Register a Notice of Intent to prepare an EIS and file their draft and final EISs with EPA, which publishes weekly notices in the Federal Register listing EISs available for public review and comment. CEQ’s regulations implementing NEPA require federal agencies to solicit public comment on draft EISs. When the public comment period is finished, the agency proposing to carry out or permitting a project is to analyze comments, conduct further analysis as necessary, and prepare the final EIS. In the final EIS, the agency is to respond to the substantive comments received from other government agencies and the public. Sometimes a federal agency must prepare a supplemental analysis to either a draft or final EIS if it makes substantial changes in the proposed action that are relevant to environmental concerns, or if there are significant new circumstances or information relevant to environmental concerns. Further, in certain circumstances, agencies may—through “incorporation by reference,” “adoption,” or “tiering”—use another analysis to meet some or, in the case of adoption, all of the environmental review requirements of NEPA. Unlike other environmental statutes, such as the Clean Water Act or the Clean Air Act, no individual agency has enforcement authority with regard to NEPA’s implementation. This absence of enforcement authority is sometimes cited as the reason that litigation has been chosen as an avenue by individuals and groups that disagree with how an agency meets NEPA requirements for a given project. For example, a group may allege that an EIS is inadequate, or that the environmental impacts of an action will in fact be significant when an agency has determined they are not. Critics of NEPA have stated that those who disapprove of a federal project will use NEPA as the basis for litigation to delay or halt that project. Others argue that litigation only results when agencies do not comply with NEPA’s procedural requirements. Governmentwide data on the number and type of most NEPA analyses are not readily available, as data collection efforts vary by agency (see app. II for a summary of federal NEPA data collection efforts). Agencies do not routinely track the number of EAs or CEs, but CEQ estimates that EAs and CEs comprise most NEPA analyses. EPA publishes and maintains governmentwide information on EISs. Many agencies do not routinely track the number of EAs or CEs. However, based on information provided to CEQ by federal agencies, CEQ estimates that about 95 percent of NEPA analyses are CEs, less than 5 percent are EAs, and less than 1 percent are EISs. These estimates were consistent with the information collected on projects funded by the American Recovery and Reinvestment Act of 2009 (Recovery Act). Projects requiring an EIS are a small portion of all projects but are likely to be high-profile, complex, and expensive. As the Congressional Research Service (CRS) noted in its 2011 report on NEPA, determining the total number of federal actions subject to NEPA is difficult, since most agencies track only the number of actions requiring an EIS. The percentages of EISs, EAs, and CEs vary by agency because of differences in project type and agency mission. For example, the Department of Energy (DOE) reported that 95 percent of its 9,060 NEPA analyses from fiscal year 2008 to fiscal year 2012 were CEs, 2.6 percent were EAs, and 2.4 percent were EISs or supplement analyses. Further, in June 2012, we reported that the vast majority of highway projects are processed as CEs, noting that the Federal Highway Administration (FHWA) within the Department of Transportation (DOT) estimated that approximately 96 percent of highway projects were processed as CEs, based on data collected in 2009. Representing the lowest proportion of CEs in the data available to us, the Forest Service reported that 78 percent of its 14,574 NEPA analyses from fiscal year 2008 to fiscal year 2012 were CEs, 20 percent were EAs, and 2 percent were EISs. Of the agencies we reviewed, DOE and the Forest Service officials told us that CEs are likely underrepresented in their totals because agency systems do not track certain categories of CEs considered “routine” activities, such as emergency preparedness planning. For example, DOE officials stated that the department has two types of CEs, those that (1) are routine (e.g., administrative, financial, and personnel actions; information gathering, analysis, and dissemination) and are not tracked and (2) are documented as required by DOE regulations. EPA publishes and maintains governmentwide information on EISs, updated when Notices of Availability for draft and final EISs are published in the Federal Register. CEQ and NAEP publish publicly available reports on EISs using EPA data. As shown in table 1, the three compilations of EIS data produce different totals. According to CEQ and EPA officials, the differences in EIS numbers shown in table 1 are likely due to different assumptions used to count the number of EISs and minor inconsistencies in the EPA data compiled for the CEQ and NAEP reports and for our analysis of EPA’s data. CEQ obtains the EIS data it reports based on summary totals provided by EPA. Occasionally, CEQ also gathers some CE, EA, and EIS data through its “data call” process, by which it aggregates information submitted by agencies that use different data collection mechanisms of varying quality. According to a January 2011 CRS report on NEPA, agencies track the total draft, final, and supplemental EISs filed, not the total number of individual federal actions requiring an EIS. In other words, agency data generally reflect the number of EIS documents associated with a project, not the number of projects. Four agencies—the Forest Service, BLM, FHWA, and the U.S. Army Corps of Engineers within the Department of Defense (DOD)—are generally the most frequent producers of EISs, accounting for 60 percent As of the EISs in 2012, according to data in NAEP’s April 2013 report. shown in table 2, these agencies account for over half of total draft and final EISs from 2008 through 2012, according to NAEP data. NAEP, Annual NEPA Report 2012 of the National Environmental Policy Act (NEPA) Practice (April 2013). Little information exists at the agencies we reviewed on the costs and benefits of completing NEPA analyses.