Growth in North American crude oil and natural gas production has resulted in efforts to expand the domestic oil and natural gas pipeline network. Pipelines can be a cost-effective and comparatively safe means of hydrocarbon transport. Pipelines and their routes also can be controversial locally, regionally, or nationally. While many new or expanded pipelines have been proposed and completed in recent years, other proposed pipelines have been unable to satisfy all the requirements to obtain federal authorizations, have faced barriers among state regulatory agencies, and have been the subject of litigation. Congress has a long-standing interest in pipeline development and the regulation of pipelines because of the critical role of pipelines in the domestic energy markets. Failure to construct pipelines may result in various potential effects, such as greater reliance on road or rail transport and constraints on getting oil and natural gas resources to refineries, power plants, and other consumers—all of which can create economic inefficiencies. Local interests along proposed pipeline routes regularly have raised concerns about the local environmental and other impacts of pipeline construction; they also have expressed concerns about the risks during pipeline operations of accidents that could affect the environment and human health. In recent years, stakeholders interested in reducing U.S. reliance on fossil fuels or promoting other energy sources and energy conservation have brought greater public attention both to oil and natural gas pipelines and to federal and state decisions related to new pipelines in particular. Some of these pipeline opponents argue that pipelines may facilitate the use of oil and natural gas, thereby indirectly contributing to the human health, welfare, and environmental effects of oil and natural gas production and use. Pipeline proponents argue that the impacts of development and use of natural gas may be less than impacts associated with other energy sources and that both oil and natural gas pipelines contribute to the nation's energy security and provide broad benefits to the U.S. economy. This report discusses how the U.S. Army Corps of Engineers (Corps) administers its responsibilities related to certain pipeline segments that require Corps authorizations. The Corps is one of many federal agencies with responsibilities that may relate to oil and natural gas pipelines. Interest in federal approvals and requirements for pipelines relates to a broader policy issue before Congress: What is the appropriate federal role in protecting the environment, public health, national economy, and domestic energy security when reviewing and authorizing activities associated with private development of energy-sector or other infrastructure? The role of the Corps in authorizing oil and natural gas pipelines is limited to (1) the agency's regulatory authorities for authorizing activities affecting regulated water bodies and wetlands and activities that alter or obstruct navigable waters and (2) its civil works authorities, including allowing a pipeline to cross a Corps water resource project and related lands. Because most pipelines cross regulated water bodies, the Corps must authorize the activities at those crossings before construction at those locations can commence. Because the Corps has no broad authority related to pipelines along their entire domestic routes, the agency's analyses to support its authorization decisions are scoped to focus on the application of Corps authorities to specific pipeline segments. Controversy regarding the Dakota Access Pipeline (DAPL), a crude oil pipeline from North Dakota to Illinois, focused attention on the Corps' authorizations and approvals. This attention to the Corps may continue, given the renewed efforts for the international Keystone XL, proposed domestic pipelines, and related litigation. This report provides an overview of the agency's role with respect to oil and natural gas pipelines. Because the Corps' pipeline-related decisions can be controversial, the report also introduces some of the issues raised. After an overview of the Corps and the broader federal role in approving private oil and natural gas pipelines, the remainder of the report discusses how the Corps' regulatory responsibilities apply where pipelines cross water bodies and wetlands (i.e., Corps regulatory program); how the Corps' civil works authorities may apply if a pipeline may alter or affect a Corps water resource project or may cross Corps-managed land (i.e., Corps civil works program); how the Corps complies with various federal statutes as it arrives at pipeline-related decisions, including the environmental documentation requirements of the National Environmental Policy Act (NEPA) and the historic preservation requirements of the National Historic Preservation Act (NHPA); and how the agency's role in pipelines raises or illustrates various policy issues for decisionmakers. Siting, construction, and operation of oil and natural gas pipelines may be subject to a number of local, state, tribal, and federal requirements. Whether the entire pipeline will require federal agency authorization generally depends on the commodity the pipeline would transport and whether it would cross state lines. Specifically, the siting, construction, and operation of interstate natural gas pipelines must be authorized by the Federal Energy Regulatory Commission (FERC), in accordance with requirements established under Section 7(c) of the Natural Gas Act of 1938; in contrast, domestic oil pipelines and intrastate natural gas pipelines are not subject to a similar federal authorization for their entire routes. Federal pipeline safety standards also could affect pipeline siting, construction, operation, and maintenance. The Department of Transportation's Pipeline and Hazardous Materials Safety Administration (PHMSA) is the principal federal agency charged with ensuring the safe interstate movement of natural gas and hazardous liquids, including crude oil. Congress tasked the Department of Transportation, working through PHMSA, with regulating key aspects of interstate pipeline safety, including design, construction, operation and maintenance, and spill response planning. For more information on the Department of Transportation's safety program, see CRS Report R44201, DOT's Federal Pipeline Safety Program: Background and Key Issues for Congress , by [author name scrubbed], and see the box later in this report titled "PHMSA Pipeline Safety Regulation and Corps Permit Conditions Related to Safety." Specific aspects or activities associated with pipelines may be subject to federal agency approval. For example, separate federal agency authorization (in the form of a permit or other approval) may be required if the proposed pipeline, in whole or in part, would cross federal land or potentially would affect an environmental, natural, or cultural resource protected under federal law. As discussed below, the involvement of the Corps in pipelines generally is limited to those pipeline segments that would cross Corps-managed federal land (hereinafter referred to as Corps land ) or a Corps-managed federal flood easement on nonfederal land and to those pipeline activities that may affect or cross waters and wetlands regulated by the agency. Although the Corps has no authority to approve pipelines, certain pipeline segments and their construction may require Corps authorizations. Under the agency's regulatory program, the Corps is responsible for authorizing activities that could affect federally regulated waters and wetlands. Under its civil works program, the agency is responsible for approving activities that cross or affect Corps lands and projects. A pipeline developer must have authorization from the Corps regulatory program (sometimes referred to as its permit program) for any pipeline segment affecting or crossing Corps jurisdictional water, in accordance with Section 404 of the Clean Water Act, under which the Corps regulates the discharge of dredged or fill material into waters of the United States, including wetlands; and Section 10 of the Rivers and Harbors Act of 1899, under which the Corps regulates structures and/or work in or affecting the course, condition, or capacity of navigable waters. Because pipelines of any significant length will cross or otherwise may affect U.S. waters somewhere along their routes, pipeline developers are routinely required to have authorization from the Corps under Section 404 of the Clean Water Act (hereinafter Section 404) and/or under Section 10 of the Rivers and Harbors Act (hereinafter Section 10). The Corps regulates all activities affecting regulated waters; for pipelines, the Corps regulates activities whether the pipeline is interstate or intrastate and whether the pipeline is transporting oil or natural gas. A pipeline developer may need certain approvals from the civil works program of the Corps if the proposed pipeline could affect a Corps water resource project or Corps land and real estate interests. Corps land and other real estate interests (e.g., private lands with a federal flood or other flowage easement) typically were acquired as part of a water resource project. For pipelines to cross below, on, or above Corps land and non-Corps land with a Corps real estate interest, the agency generally will decide on granting both a Corps permission to alter a Corps civil works project; and a Corps easement to cross Corps land or a consent to cross non-Corps land with a Corps real estate interest. Figure 1 illustrates pipeline segments over which the Corps may have some role, specifically segments that would cross Section 404 Corps-regulated waters and wetlands or Section 10 Corps-regulated waters (and therefore would involve a role for the agency's regulatory program) and Corps land (and therefore would involve a role for the agency's civil works program). Figure 1 also illustrates FERC involvement in authorizing the siting and construction of interstate natural gas pipelines; no federal agency has a similar role for domestic interstate or intrastate oil pipelines or for intrastate natural gas pipelines. Stakeholders with an interest in pipeline construction sometimes have focused on the role of the Corps in pipeline-related approvals when no other federal agency has authority to approve the entire pipeline, which primarily is the case for domestic pipelines transporting crude oil. In the case of the DAPL to transport crude oil, the pipeline route selected crossed Corps-regulated waters and Corps land at Corps water resource projects. For more on the DAPL, see the box "Why Was the Corps the Main Federal Agency Involved in the DAPL Debate?" The Corps is responsible for authorizing activities that may affect waters over which it has jurisdiction under Section 404 or Section 10. The agency performs this work as part of its regulatory program. The types of projects that may cause impacts to regulated waters vary widely, including navigation, coal mining, riverbank stabilization, and transportation projects. One category of activities is a water or wetland crossing by a utility line, which includes oil and natural gas pipelines. The Corps' regulatory authorities are limited by statute to activities affecting waters and wetlands regulated pursuant to the Section 404 and Section 10 authorities. That is, the agency's regulatory jurisdiction does not extend to a pipeline's entire route; it is limited to the crossings of regulated waters, as shown in Figure 1 . Therefore, the Corps generally does not regulate the largest components of pipeline projects because it does not have regulatory jurisdiction over portions of the pipeline that cross upland areas. Authorizations pursuant to the Corps regulatory authorities fall under two categories of permits—individual permits and general permits. Actions authorized through general permits represented almost 94% of the Corps' 53,825 regulatory actions in FY2016. Activities that may or are expected to have significant adverse impacts on regulated waters require individual permits. The Corps (or states that have been delegated the authority to administer Section 404 permits) can process individual permits as standard individual permits or through an abbreviated process known as a Letter of Permission procedure (which can vary by state). Each standard individual permit is subject to public notice, public interest review, public hearing, activity-specific environmental documentation, and case-by-case evaluation (including an evaluation of alternatives), so these permits typically require more time than general permits before an activity is authorized. Public notification is not required for individual permits processed using Letters of Permission procedures. The Corps issues general permits for activities that are similar in nature and that are expected to have minimal adverse effect on waters and wetlands both individually and cumulatively. General permits essentially preauthorize a group of similar activities on a programmatic level. The Corps uses general permits to minimize the permit processing burden of its regulatory program on both itself and applicants. General permits authorize applicants to proceed without the more time-consuming need to obtain standard individual permits in advance. The lower processing burden of general permits creates an incentive for applicants to reduce the impacts of their activities on regulated waters and wetlands in order to qualify for a general permit. During the process required for the Corps to issue a general permit, the general permit is subject to public notice, public interest review, public hearing, and environmental documentation; the specific actions undertaken pursuant to the general permit do not go through these steps. The Corps issues a range of general permits, including Nationwide permits (NWPs), which cover a wide range of activities—such as aids to navigation, minor dredging, and bank stabilization. There are 52 NWPs in force. Regional conditions also can be applied to NWPs. Other general permits that apply in a single state or regionally. Programmatic permits are built on an existing state, local, or other federal agency program and are designed to avoid duplication between the existing program and Corps efforts. Regional permits are a type of general permit issued by a division or district engineer at the Corps. Nationwide and other general permits are issued for five-year terms; the permits automatically expire and become null and void (and cannot be extended) if they are not modified or reissued within five years of their effective date. The current NWPs took effect on March 19, 2017, for a five-year period. Pipeline activities that require Corps authorization and that are similar in nature with minimal environmental impacts (e.g., minor stream crossings) may qualify for a general permit. It typically would be NWP 12 (which is discussed in more detail in " Nationwide Permit 12: Utility-Line Activities ," below), unless a state or regional general permit applies. To qualify for NWP authorization, proposals must meet a number of general conditions (GCs). (See section titled " General Conditions Required for NWP Authorization " for more information). Many activities covered by NWPs can proceed without advance notification to the Corps, whereas other activities that can be pursued under an NWP require that the applicant submit a pre-construction notification (PCN) and obtain a verification by the Corps for use of that NWP. A PCN is a request submitted by the applicant to the Corps to confirm (i.e., verify) whether or not a particular activity is authorized by general permits. If the activity does not require the permittee to submit a PCN, the permittee determines if the activity qualifies for an NWP. Therefore, the Corps reviews the activities for which it receives a PCN but does not conduct a review of all the individual activities potentially authorized by an NWP. (See section titled " Pre-construction Notification " for more on PCNs.) If a pipeline-related crossing does not meet the conditions of a general permit or qualify for a general permit as determined by statute and regulation, the Corps district may use its discretionary authority to require use of the individual permit process. The Atlantic Sunrise natural gas pipeline is an example of a pipeline for which the Corps reviewed the application as a standard individual permit because the proposed activity would exceed the wetland loss threshold of the applicable general permit. One of the nationwide permits—NWP 12—is used to authorize utility-line activities, including the construction, maintenance, or repair of utility lines in waters of the United States. The permit defines a utility line as any pipe or pipeline for the transportation of any gaseous, liquid, liquescent, or slurry substance—including oil or natural gas—for any purpose and any cable, line, or wire for the transmission for any purpose of electrical energy, telephone, and telegraph messages and radio and television communication. NWP 12 can be used only if the activity (e.g., a water crossing) does not result in the loss of more than 0.5 acres of waters of the United States. Certain activities under NWP 12 require an approved PCN before the activity authorized by that permit may commence. An NWP 12 permit applicant must submit a PCN based on various thresholds and criteria—for example, when a Section 10 permit is required, when mechanized land clearing in forested wetlands is required for the right-of-way, or when discharges are expected to cause the loss of more than 0.1 acres of waters of the United States, among other thresholds and criteria. For NWP 12 specifically, the Corps requires that PCNs include information on other water crossings for the linear project (e.g., the pipeline) that will use NWP 12 that do not require PCNs. The Corps estimates that NWP 12 is used on average approximately 11,500 times per year on a national basis, affecting approximately 1,700 acres of U.S. waters, including wetlands regulated under the Clean Water Act. The total includes about 9,000 uses per year for activities that involve submitting a PCN to the Corps and about 2,500 uses for activities that do not require a PCN. Individual NWP 12 verifications do not require NEPA documentation, nor do they require an opportunity for public comment. The public comment opportunity occurs during the rulemaking procedure for the NWP itself, not with each verification or use of the permit. Whereas for some pipelines Corps regulatory information is publicly available through Corps districts, FERC dockets, or court documents, no nationally aggregated data are available on NWP 12 use that is specifically about oil and natural gas pipelines. The 11,500 NWP 12 authorizations cited are not specific to pipelines; the figure includes all utility-line activities. Furthermore, although NWP 12 covers a large majority of utility-line activities, some pipeline activities may not qualify for NWP 12 and may require individual permits. The publicly available database that the Corps maintains on individual permits is not designed to track which individual permits are related to oil and gas pipelines, and no publicly available database is available that tracks each verification for NWP 12 activities related to pipelines specifically or utility lines more broadly. By statute, activities that have the potential to result in more than minimal individual and cumulative adverse effects on the aquatic environment cannot be authorized by NWPs, including NWP 12. To ensure that individual activities do not exceed that level of impact, each NWP rulemaking includes general conditions (GCs) that a permittee must comply with, as applicable. The NWPs reissued in 2017 detail 32 GCs that apply to any activity using an NWP for its authorization, including the following: Navigation (GC 1). No activity may cause more than minimal adverse effects on navigation. Water Supply Intakes (GC 7). No activity may occur in the proximity of a public water supply intake, except where the activity is for the repair or improvement of public water supply intake structures or adjacent bank stabilization. Management of Water Flows (GC 9). To the maximum extent practicable, the pre-construction course, condition, capacity, and location of water flows must be maintained. Proper Maintenance (GC 14). Any authorized structure or fill shall be properly maintained, including maintenance to ensure public safety and compliance with applicable NWP GCs, as well as any activity-specific conditions added by the district engineer to an NWP authorization. (For information on how pipeline safety is addressed and how it relates to GC 14, see box titled "PHMSA Pipeline Safety Regulation and Corps Permit Conditions Related to Safety.") Tribal Rights (GC 17). No NWP activity may cause more than minimal adverse effects on tribal rights (including treaty rights), protected tribal resources, or tribal lands. Endangered Species (GC 18). No activity may be authorized if it is likely to directly or indirectly jeopardize the continued existence of a threatened or endangered species or a species proposed for such designation, as identified under the federal Endangered Species Act (ESA), or if it will directly or indirectly destroy or adversely modify the critical habitat of such species. Historic Properties (GC 20). In cases where the district engineer determines that the permitted activity may affect properties listed, or eligible for listing, in the National Register of Historic Places, no activity may be authorized until the requirements of Section 106 of NHPA have been satisfied. Section 106 requires federal agencies to take into account the effect of their undertakings on any historic property. Mitigation (GC 23). The district engineer must consider specific factors when determining appropriate and practicable mitigation measures to ensure that any adverse effects on the aquatic environment are minimal (e.g., to the maximum extent practicable, the activity must be designed and constructed to avoid and minimize temporary and permanent adverse effects, at the project site, to waters of the United States). Water Quality (GC 25). The permittee must obtain an individual water quality certification or waiver for discharges authorized by the NWP if the state or authorized tribe has not previously certified compliance of the NWP with Section 401 of the Clean Water Act. Pre-construction Notification (GC 32). The permittee is required to provide a PCN as specified in each NWP. Unlike with individual permits, activities in regulated waters can be conducted pursuant to NWPs without an evaluation of alternatives to those activities (e.g., a water crossing proposed by a pipeline developer can be authorized under the NWP without the Corps evaluating alternative crossing locations). For verification under an NWP, GC 18 and GC 20 may require the use of the NWP to be reviewed if the activity may adversely affect federally listed endangered or threatened species or historic properties. For more on NWP and ESA compliance, see box "Nationwide Permits and Endangered Species Act Compliance." For more on historic properties compliance, see this report's section titled " Corps Procedures for Protecting Historic Properties ." GC 32 specifies that the permittee is required to submit a PCN to the Corps pursuant to the applicable NWP; it also establishes the information required for inclusion in the PCN and the timing of the agency's review of the PCN. When a PCN is submitted, the Corps has 30 days to determine whether a PCN is complete. The Corps district engineer has 45 days to review a complete notification under most NWPs, including NWP 12, unless the proposed activity requires an ESA Section 7 consultation and/or NHPA Section 106 consultation. If no ESA or NHPA consultation is required, the proposed work generally may not proceed without written confirmation from the district engineer; however, if no decision is issued during the 45-day review period, the permittee may presume that the activity qualifies for the NWP. If ESA or NHPA consultation is required, the proposed work may not begin before receiving a written NWP verification. PCNs and their verifications are not required to be published, nor must a public comment opportunity be provided during the review period. The public may not be aware that a PCN has been submitted to the Corps. As noted, the majority of oil and natural gas pipeline activities subject to the Corps regulatory program are authorized via NWP 12. Some stakeholders have criticized the Corps for relying on NWP 12 to authorize pipeline-related activities. A primary concern is that the NWP process does not allow for a separate environmental review of each activity or set of activities for a pipeline project proceeding under NWP 12. The agency's position is that, if applicable general conditions and limits for using the NWP are met, the environmental impacts would be minimal. The Corps has developed the general conditions for the use of NWP 12 to establish compliance with federal laws related to species, historic properties, and environmental impacts. Some critics contend that permittees that are not required to submit PCNs make their own determinations about project-specific conditions without Corps review. Another criticism relates to the scope of environmental impacts considered for projects under NWP 12. NWPs can be used only for a "single and complete project" that will cause only minimal adverse environmental effects, individually or cumulatively. The Corps defines a single and complete project as a portion of a total project that includes all crossings of a single water body at a specific location. Thus, NWP 12 can be used multiple times for a single pipeline with numerous water crossings if each crossing does not result in the loss of greater than 0.5 acres of waters of the United States. Therefore, the "project" that is subject to Corps authorization is not the entire pipeline but rather the discrete segments that cross waters subject to the agency's regulatory jurisdiction. Critics say that such segmenting of a pipeline when NWPs are used fails to account for cumulative effects. Legal challenges to the use of NWPs along these lines of argument have been largely unsuccessful. If a proposed nonfederal pipeline of any type or other nonfederal activity would cross or otherwise use federal lands, the developer generally is required to obtain the appropriate real estate interest (e.g., an easement providing a right-of-way for the pipeline) from the federal agency authorized to administer that land. The Corps owns 7.6 million acres of land and manages another 4.1 million acres, often through federal flowage easements on nonfederal, frequently private, land. The Corps is responsible for these lands because they are part of Corps civil works projects. The agency's inventory of civil works projects includes 702 dams and associated reservoirs and 14,500 miles of Corps-constructed levees. A pipeline developer also is required to obtain the agency's permission prior to altering or otherwise affecting the operations of a Corps civil works project. For requests to have pipelines cross below, on, or above Corps land and non-Corps land with a Corps real estate interest, the Corps generally will decide on whether or not to grant both a permission to alter a Corps civil works project and an easement to cross Corps land or a consent to cross non-Corps land with a Corps real estate interest. Corps authority to allow alterations to its projects derives from Section 14 of the Rivers and Harbors Act of 1899, also known as Section 408 based on its codification at 33 U.S.C. §408. This provision states that the Secretary of the Army may "grant permission for the alteration or permanent occupation or use of any of the aforementioned public works when in the judgment of the Secretary such occupation or use will not be injurious to the public interest and will not impair the usefulness of such work " (emphasis added). A Section 408 permission is required for all alterations to Corps projects, not only alterations by pipelines. For pipelines over 24 inches (24″) in diameter, the Corps conducts a technical review of the proposed pipeline's effects on Corps projects pursuant to Engineer Circular (EC) 1165-2-216, Policy and Procedural Guidance for Processing Requests to Alter US Army Corps of Engineers Civil Works Projects Pursuant to 33 USC 408 . For more details on the technical review conducted for deciding to grant, grant with conditions, or deny a Section 408 permission, see the box "Section 408 Permissions: Guidance Since 2015 and Congressional Action." For smaller pipelines and other encroachments of a more routine or minimal nature, the Corps complies with Section 408 by following the process established in Chapter 17, "Non-Recreation Outgrant Policy," of Engineer Regulation (ER) 1130-2-550, Recreation Operations and Maintenance Policies . Federal agencies, including the Corps, may grant an easement for oil and natural gas pipelines to cross federal land in accordance with the provisions of Section 28 of the Mineral Leasing Act (MLA). The Corps also can consent to a pipeline crossing non-Corps lands with a Corps real estate interest (e.g., flowage easement) using a broad, military-wide real estate authority. If a Section 408 permission is needed, the easement or consent is contingent upon the granting of the Section 408 permission. Since 1973, the MLA requires that two congressional authorizing committees—the House Natural Resources Committee and the Senate Energy and Natural Resources Committee—be notified if the developer of an oil or natural gas pipeline with a diameter of 24″ or greater is requesting to cross federal land. The Corps also must notify the committees if it intends to grant an easement and must provide "detailed findings as to the terms and conditions" to be imposed on the applicant. The MLA is not more specific about what the contents of these notifications, nor does it provide guidance about when an agency may grant the rights-of-way application in relation to the committee notification. The Corps released a policy guidance memorandum in 2008 for easements of pipelines that are 24″ or larger. The policy direction therein regarding congressional notification and the granting of the rights-of-way states: "If the Committee does not provide an affirmative response, [the Corps] District will wait 14 days following Committee notification before execution of the easement." The Administration can waive this policy-based waiting period. To decide on easements and consents, the Corps follows Chapter 8 of ER 405-1-12, Real Estate Handbook , and Army Regulation (AR) 405-80, Management of Title and Granting Use of Real Property . ER 405-1-12 requires that the Corps find that "the proposed easement will not be inconsistent with the authorized purposes of the Federal installation or project." According to ER 405-1-12, site-specific environmental, cultural, and operational requirements may be added to the easement or consent; also, the Corps is to impose any special requirements for safe operation of a pipeline or related facilities. For example, according to the Corps, the Lake Oahe easement for DAPL "contains 36 conditions that are intended to further mitigate risk of rupture at the Lake Oahe crossing," including specific coatings to prevent corrosion, corrosion surveys after installation, more stringent enforcement of the pipeline's oil spill facility response plan, mainline valve and automatic shutdown requirements, and measures for initial and ongoing leak and crack detection. If the Corps finds that the pipeline is not inconsistent with the authorized purposes of the Corps project and its lands, the Corps signs a real estate instrument that grants the easement. If the pipeline crosses lands administered by the Corps and at least one other federal agency, the Secretary of the Interior is authorized, after consultation with the agencies involved, to grant or to deny the easement. Each agency head remains responsible for administering and enforcing the easements, as they involve lands under the agency head's jurisdiction. Figure 2 illustrates the relationship between the Section 408 permission, the real estate or consent process, and the MLA congressional notification requirements for proposed pipelines. The Section 408 permission process is shown in the grey boxes on the left side of Figure 2 . The process to grant or deny the easement or consent is shown in the tan boxes on the right side of Figure 2 . The MLA notification requirements are shown in the green boxes in Figure 2 . As part of the process of granting an easement or consent, the Corps must comply with federal statutes. The Corps typically evaluates this compliance as part of its NEPA documentation. For a request that requires both a Section 408 permission and an easement or consent by the Corps, the NEPA document is produced as part of the technical review for the Section 408 permission. As part of the technical review process, the Corps documents and demonstrates that it has gathered relevant information from the pipeline developer and that it has analyzed that and any additional information necessary to determine what federal requirements may apply to the Corps' actions. During that process, the Corps determines the resources potentially affected by granting the permission and easement or consent, and it determines whether the impacts to those resources would trigger actions necessary for compliance with other federal laws, such as Section 106 of NHPA and Section 7 of ESA, among others. As previously noted, Corps regulatory actions and civil works actions may be subject to other federal statutes, such as NEPA, NHPA, and ESA. Part of the compliance may include consultation or input from other entities. Table 1 lists selected federal laws that, if applicable to a Corps pipeline-related action, may require the Corps to consult with relevant state or tribal entities or with other federal agencies. Most requirements listed in the table are limited to actions taken by federal agencies. For example, an oil pipeline constructed on private land that does not require a federal agency approval (e.g., a pipeline that does not cross Corps jurisdictional waters or federal lands) would not be subject to NEPA or NHPA. As shown in Table 1 , federal licenses and approvals, such as Corps individual permits, generally are conditioned on the permittee obtaining a state or tribal water quality certification pursuant to Section 401 of the Clean Water Act and a state or tribal consistency concurrence pursuant to the Coastal Zone Management Act. For the NWPs, compliance with Section 401 of the Clean Water Act is accomplished by satisfying GC 25. The state or tribe can certify all activities authorized by an NWP or require that verifications of certain activities under an NWP obtain state or water quality certification. The state or tribe can approve, deny, or condition its certification. Although the Corps is not part of the process for the permittee to obtain a state or tribal water quality certification, the denial of a water quality certification can affect the Corps' regulatory authorizations for pipelines. For example, the developer of the Northern Access Pipeline to transport natural gas from Pennsylvania to New York has planned on using the NWP 12 for 276 wetland and 192 stream crossings. In April 2017, the New York State Department of Environmental Conservation (NYSDEC) denied the state water quality certification pursuant for the April 2016 application for the 94-mile pipeline. Until the pipeline developer complies with Section 401 of the Clean Water Act, the Corps will be unable to allow the permittee to proceed in New York under NWP 12 because of the permit's GC 25 on water quality. Individual permits also require state water quality certification. The pipeline developer can address the concerns that led to the NYSDEC denial and submit a new application to NYSDEC for a state water quality certification or pursue a public hearing within 30 days of the denial consistent with New York regulations. A detailed discussion of how state approvals, and the state water quality certification in particular, may affect federal approvals for pipelines is beyond the scope of this report. The remainder of this section addresses two agency-specific procedures that the Corps has adopted for its regulatory program: NEPA procedures and historic properties procedures. The Corps regulations implementing the agency's regulatory program include procedures to implement NEPA and to provide for the protection of historic properties. Those procedures reveal the agency's interpretation of the limits to its jurisdiction; that is, the procedures reflect that the Corps interprets its regulatory authorities under Section 404 and Section 10 as not extending to private actions upland of regulated waters. NEPA requires federal agencies to identify and consider the environmental impacts of an action before a final decision is made about that action. Regulations implementing NEPA were promulgated by the Council on Environmental Quality (CEQ). Those regulations identify federal actions subject to NEPA to include those over which a federal agency has some control or responsibility. Each federal agency was required to adopt the CEQ regulations, supplement them as necessary to include procedures relevant to that agency's authority, and ensure that those procedures implementing NEPA are integrated into the agency's broader decisionmaking procedures. The Corps adopted and supplemented the CEQ regulations in its own Procedures for Implementing NEPA. Further, the Corps provides additional procedural guidance for preparing and processing NEPA documents for regulatory actions in Appendix B to the regulations implementing its regulatory program. Under NEPA, a project known to have a significant impact on the environment requires the preparation of an environmental impact statement (EIS). When impacts are uncertain, an environmental assessment (EA) is prepared to determine if an EIS is needed or a finding of no significant impacts (FONSI) may be issued. The Corps has identified "regulatory actions" (i.e., issuance of a permit) among the actions that normally require an EA but not necessarily an EIS. The Corps does not require NEPA review for individual NWP verifications. Instead, to date, the federal action subject to NEPA has been issuance of NWP 12. During the public rulemaking for each of these five-year permits, NEPA compliance has involved preparation of an EA that resulted in Corps issuance of a final decision document (its version of a FONSI). The Corps EA/decision document for NWP 12 has been prepared, in part, to identify conditions that must be met to ensure that authorization via an NWP is appropriate. Part of the process to develop the decision document is the identification of general conditions to ensure that activities related to a single and complete project will have minimal adverse environmental effects (i.e., no significant impacts that would require the preparation of an EIS). Understanding the scope of Corps NEPA reviews is useful in recognizing how far upland the Corps will evaluate the impacts of a larger project (e.g., a pipeline that extends beyond Corps-regulated waters). As noted, under NEPA, the Corps is required to evaluate the impacts of an action over which it has control and responsibility. Depending on the details of the activity subject to Corps approval, the agency's interpretation of the extent of its control and responsibility over a proposed action will dictate the geographic area over which environmental impacts are evaluated (i.e., how far upland from regulated waters the agency will review the impacts of a larger project). For a discussion of the geographic limits of Corps environmental reviews for pipelines, see the box titled "Geographic Limits of Corps Environmental Reviews." The Corps established "Procedures for the Protection of Historic Properties" in Appendix C to its regulations applicable to Department of the Army permits. The Corps follows Appendix C to fulfill the procedural requirements set forth in NHPA, other applicable historic preservation laws, and presidential directives as they relate to the Corps regulatory program. Section 106 of NHPA provides that federal agencies, prior to expending federal funds or granting a license to any undertaking over which they have direct or indirect jurisdiction, must "take into account the effect of [the] undertaking on any historic property." If historic properties might be affected, the agency must consult with the state historic preservation officer or tribal historic preservation officer, as applicable, about alternatives to avoid, minimize, or mitigate adverse effects to those properties. The Advisory Council on Historical Preservation (ACHP), an independent federal agency established under NHPA to promote and advise on historic preservation, also may be involved in consultations under certain circumstances. Procedures for NHPA Section 106 compliance for the regulatory program of the Corps have been the subject of disagreements with the ACHP and some other stakeholders. According to 2016 ACHP communications to the Corps, the ACHP has not accepted the Corps procedures as being consistent with ACHP regulations. Some federal district courts have declined to apply the agency's procedures, on the bases of inconsistency with NHPA or non-approval by the ACHP; however, others have cited or applied the Corps procedures. The ACHP has objected particularly to the decision by the Corps to review each water crossing by a linear project, such as a pipeline, as a separate undertaking. The ACHP regulations define an "undertaking" as "a project, activity, or program funded in whole or in part under the direct or indirect jurisdiction of a Federal agency, including those carried out by or on behalf of a Federal agency; those carried out with Federal financial assistance; and those requiring a Federal permit, license or approval." The ACHP contends that this definition would in many cases require the Corps to conceive of the "undertaking" as broader than a single water crossing. The approach used by the Corps, the ACHP states, "dismiss[es] the potential for effects to historic properties that may be located within the broader project area of an undertaking when properly defined under the Section 106 regulations." The Corps maintains that its procedures for historic properties in Appendix C satisfy the requirements of NHPA Section 106. The Corps explained its interpretation of an undertaking related to pipelines as follows: For oil pipelines and other utility lines, the activities that are subject to the Corps' regulatory authorities and require DA [Department of Army] authorization are crossings of jurisdictional waters and wetlands, as well as utility line substations, foundations for overhead utility lines, and access roads, that involve discharges of dredged or fill material into waters of the United States or structures or work in navigable waters of the United States. Segments of an oil pipeline or other utility line in upland areas outside of the Corps' jurisdiction, or attendant features constructed in upland areas, do not require DA authorization and therefore are not, for the purposes of the Corps' compliance with section 106 of the NHPA, "undertakings." The Corps does not have direct or indirect jurisdiction over pipeline segments in upland areas. The Corps does not regulate oil pipelines, or other utility lines per se; we only regulate those components of oil pipelines or other utility lines, that involve activities regulated under our authorities (i.e., section 404 of the Clean Water Act and section 10 of the Rivers and Harbors Act of 1899). The Corps indicates in this statement its position that the agency has neither direct nor indirect jurisdiction over the entire pipeline and that its control does not extend to areas upland of regulated waters. The essence of this interpretation was adopted by one district court, the U.S. District Court for the District of South Dakota, in Standing Rock Sioux Tribe v. U.S. Army Corps of Engineers . However, as noted above, other district courts have declined to apply other elements of the agency's procedures on the basis of inconsistency with NHPA or lack of approval by the ACHP. Separately, stakeholders have raised concerns about the Corps' procedures whereby the permit applicant, rather than the Corps itself, is responsible for identifying historic properties that may be affected by a pipeline activity under an NWP. The ACHP regulations specify that "[i]t is the statutory obligation of the Federal agency to fulfill the requirements of section 106," including identification of historic properties that may be affected by an undertaking. For pipeline activities that occur under NWP 12, GC 20 provides that the Corps must initiate Section 106 review and consultation when an applicant identifies historic properties in a PCN. Once a PCN is submitted, the activity cannot proceed until the Corps district engineer completes a site-specific analysis and verifies either that the activity will not affect any eligible historic site or that the consultations required by NHPA are complete. However, the Corps does not undertake the analysis unless the project applicant raises the issue through a PCN. For pipeline activities that require individual permits, by contrast, the Corps district engineer is responsible for identifying historic properties that may be affected by the permitted activity and completing consultations as necessary. Growth in North American crude oil and natural gas production has led to efforts to expand the domestic oil and natural gas pipeline network. Pipeline construction and operation may impact the environment, human health, and welfare. The interest in expanding the domestic pipeline network and the concerns about the local, regional, and national effects of pipeline construction and operation have raised policy questions about how the Corps' regulatory authorities and civil works processes may influence the development and approval of pipelines and their routes. The Corps is authorized as part of its regulatory program to regulate certain pipeline activities that may affect certain waters and wetlands; it also is authorized to grant permissions, easements, and consents for pipeline segments that cross Corps water resources projects and associated lands. These Corps roles in pipelines are not without controversy. Some of the issues raised center on the following policy questions: I mpacts . How does the Corps determine the geographic area for its evaluations of impacts on the environment, historic properties and cultural resources, communities, and specific population groups? How does the Corps evaluate cumulative impacts? Limits of Agency Authority . When a pipeline is largely a nonfederal undertaking and the federal role is limited to discrete segments, to what extent should the federal government shape siting and other aspects of the pipeline? Risk and Safety . To what extent is the Corps authorized to address oil and natural gas pipeline safety (e.g., risk of spills) as part of its regulatory authorizations and civil works decisions? How are low-probability, high-consequence safety risks considered and addressed in the Corps' decisionmaking processes? Public Interest . How does the Corps arrive at and document its assessment of public interest in its pipeline-related regulatory and civil works activities? That is, how are anticipated costs and benefits (both monetized and non-monetized) for one group weighed relative to costs and benefits for another group, and how is the national public interest considered? General Permits . How does the use of general permits (rather than individual permits) for Corps-regulated pipeline segments affect the agency's review of proposed water crossings, the information available to stakeholders and the public, and compliance with the requirements of NHPA? An extensive discussion of each of these questions is beyond the scope of this report. Many of these questions are not unique to pipelines or to the Corps; that is, many of them have been the subject of past (and ongoing) court cases related to other Corps approvals or to similar actions by other federal agencies. As Congress considers the Corps' current and future roles and the federal role in pipelines more broadly, these questions reflect some of the basic debates about federal actions associated with private infrastructure.

Summary: Growth in North American crude oil and natural gas production has led to efforts to expand the domestic oil and natural gas pipeline network. Pipeline developers are required to obtain authorizations from the U.S. Army Corps of Engineers (Corps) before constructing certain pipeline segments. Under the agency's regulatory program, the Corps is responsible for authorizing activities that may affect federally regulated waters and wetlands. Under its civil works program, the agency is responsible for approving activities that cross or may affect Corps-managed lands and Corps water resource projects. The agency's role with respect to pipelines can be controversial and may raise policy issues for Congress. Congress has a long-standing interest in pipeline development and the regulation of pipelines because of the role of pipelines in the domestic energy markets. Corps Regulation of Water Crossings. The Corps has regulatory responsibilities pursuant to Section 404 of the Clean Water Act (33 U.S.C. §1344), under which the Corps authorizes activities that may discharge dredge or fill material into waters of the United States, including wetlands. The agency also has regulatory responsibilities pursuant to Section 10 of the Rivers and Harbors Act of 1899 (33 U.S.C. §403), under which the Corps authorizes structures and work in or affecting the course, condition, or capacity of navigable waters. Because most pipelines cross or potentially affect U.S. waters and wetlands somewhere along their routes, pipeline developers routinely are required to obtain Corps authorization for some pipeline segments. The Corps authorizes most pipeline water crossings using a general permit—Nationwide Permit 12—for utility-line activities in waters of the United States. A nationwide permit essentially preauthorizes a group of activities similar in nature that are likely to have a minor effect on waters and wetlands both individually and cumulatively. Approvals Related to Corps Land and Corps Projects. A pipeline developer may need permissions from the agency's civil works program if a pipeline segment may affect or cross a Corps water resource project and Corps-managed land. That is, the Corps would need to grant (1) an easement, typically for a right-of-way, to cross federal land managed by the Corps or (2) a consent to cross non-Corps land with a Corps real estate interest (typically a federal flood easement over nonfederal land). Prior to the granting of the easement or consent, the Corps generally must provide permission for the pipeline to alter the associated Corps water resource project. The easement at a Corps project for the Dakota Access Pipeline to cross under the Missouri River in North Dakota was particularly controversial. Corps Actions Must Comply with Federal Statutes. In carrying out its regulatory and civil works authorities, the Corps complies with applicable federal requirements. For example, the Corps identifies and considers the environmental impacts of the agency's proposed action (e.g., Corps permit of an activity affecting a wetland) pursuant to the National Environmental Policy Act (NEPA; 42 U.S.C. §§4321 et seq.) and considers impacts on historic properties pursuant to the National Historical Preservation Act (NHPA; 54 U.S.C. §306108). Policy Issues. Various questions arise in policy debates on Corps' actions related to pipelines: How does the Corps determine the direct, indirect, and cumulative impacts of its decisions to authorize activities in regulated waters or Corps-managed lands? When the federal role in a pipeline is limited to approving activities at discrete segments, to what extent should federal agencies influence siting and other aspects of a pipeline? How does the use of Corps general permits affect the agency's review, information available to stakeholders and the public, and compliance with NHPA? These questions reflect some of the basic debates and challenges that Congress and other policymakers face regarding federal approvals associated with private infrastructure.