The southwestern borderlands region contains many federally managed lands and also accounts for over 97 percent of all apprehensions of undocumented aliens by Border Patrol. Over 40 percent of the United States-Mexico border, or 820 linear miles, is managed by Interior’s land management agencies and the Forest Service. Each of these land management agencies has a distinct mission and set of responsibilities, which are, respectively, managing federal land for multiple uses, such as recreation, minerals, and the sustained yield of renewable resources; conserving the scenery, natural and historical objects, and wildlife of the national park system; preserving and enhancing fish, wildlife, plants, and their habitats; and managing resources to sustain the health, diversity, and productivity of the nation’s forests and grasslands to meet the needs of present and future generations. Border Patrol is organized into nine sectors along the southwestern border. Within each sector, there are stations with responsibility for defined geographic areas. Of the 41 stations in the borderlands region in the 9 southwestern border sectors, 26 have primary responsibility for the security of federal lands, according to Border Patrol sector officials. Apprehensions of undocumented aliens along the southwestern border increased steadily through the late 1990s, reaching a peak of 1,650,000 in fiscal year 2000. Since fiscal year 2006, apprehensions have declined, reaching a low of 540,000 in fiscal year 2009. This decrease has occurred along the entire border, with every sector reporting fewer apprehensions in fiscal year 2009 than in fiscal year 2006. The Tucson Sector, however, with responsibility for central and eastern Arizona, continues to have the largest number of apprehensions. Border Patrol shares with land managers data on apprehensions and drug seizures occurring on federal land, providing such information in several ways, including in regularly occurring meetings and e-mailed reports. Border Patrol measures its effectiveness at detecting and apprehending undocumented aliens by assessing the border security status for a given area. The two highest border security statuses—”controlled” and “managed”—are levels at which Border Patrol claims the capability to consistently detect entries when they occur; identify what the entry is and classify its level of threat (such as who is entering, what the entrants are doing, and how many entrants there are); effectively and efficiently respond to the entry; and bring the situation to an appropriate law enforcement resolution, such as an arrest. Areas deemed either “controlled” or “managed” are considered by Border Patrol to be under “operational control.” The volume of undocumented aliens crossing federal lands along the southwestern border can overwhelm law enforcement and resource protection efforts by federal land managers, thus highlighting the need for Border Patrol’s presence on and near these lands, according to DHS and land management agency officials. The need for the presence of both kinds of agencies on these borderlands has prompted consultation among DHS, Interior, and Agriculture to facilitate coordination between Border Patrol and the land management agencies. The departments have a stated commitment to foster better communication and resolve issues and concerns linked to federal land use or resource management. When operating on federal lands, Border Patrol has responsibilities under several federal land management laws, including the National Environmental Policy Act of 1969, Wilderness Act of 1964, and Endangered Species Act of 1973. Under these laws, Border Patrol must obtain permission or a permit from federal land management agencies before its agents can undertake certain activities on federal lands, such as maintaining roads and installing surveillance equipment. Because the land management agencies are responsible for ensuring compliance with land management laws, Border Patrol and the land management agencies have developed several mechanisms to coordinate their responsibilities. The most comprehensive of these is a national-level agreement—a memorandum of understanding signed in 2006 by the secretaries of Homeland Security, the Interior, and Agriculture—intended to provide consistent principles to guide their agencies’ activities on federal lands. At the local level, Border Patrol and land management agencies have also coordinated their responsibilities through various local agreements. Under key federal land management laws, Border Patrol, like all federal agencies, must obtain permission or a permit from the appropriate federal land management agency to conduct certain activities—such as road maintenance—on federal lands. These land management laws include, but are not limited to, the following: National Environmental Policy Act of 1969. Enacted in 1970, the National Environmental Policy Act’s purpose is to promote efforts that will prevent or eliminate damage to the environment, among other things. Section 102 requires federal agencies to evaluate the likely environmental effects of proposed projects using an environmental assessment or, if the projects would likely significantly affect the environment, a more detailed environmental impact statement evaluating the proposed project and alternatives. Environmental impact statements can be developed at either a programmatic level—where larger-scale, combined effects and cumulative effects can be evaluated and where overall management objectives, such as road access and use, are defined—or a project level, where the effects of a particular project in a specific place at a particular time are evaluated. If, however, the federal agency determines that activities of a proposed project fall within a category of activities the agency has already determined has no significant environmental effect— called a categorical exclusion—then the agency generally does not need to prepare an environmental assessment or an environmental impact statement. The agency may instead approve projects that fit within the relevant category by using one of the predetermined categorical exclusions, rather than preparing a project-specific environmental assessment or environmental impact statement. National Historic Preservation Act of 1966. The National Historic Preservation Act provides for the protection of historic properties—any prehistoric or historic district, site, building, structure, object, or properties of traditional religious and cultural importance to an Indian tribe, included, or eligible for inclusion in, the National Register of Historic Places. For all projects receiving federal funds or a federal permit, section 106 of the act requires federal agencies to take into account a project’s effect on any historic property. In accordance with regulations implementing the act, Border Patrol and land management agencies often incorporate compliance with the National Historic Preservation Act into their required evaluations of a project’s likely environmental effects under the National Environmental Policy Act. Thus, the agency or agencies must determine, by consulting with relevant federal, state, and tribal officials, whether a project or activity has the potential to affect historic properties. The purpose of the consultation is to identify historic properties affected by the project; assess the activity’s adverse effects on the historic properties; and seek ways to avoid, minimize, or mitigate any of those effects. Wilderness Act of 1964. The Wilderness Act of 1964 provides for federal lands to be designated as “wilderness areas,” which means that such lands are to be administered in such a manner that will leave them unimpaired for future use and enjoyment and to provide for their protection and the preservation of their wilderness character, among other goals. If Border Patrol proposes to patrol or install surveillance equipment on federal land that has been designated as wilderness, the agency must comply with the requirements and restrictions of the Wilderness Act of 1964, other laws establishing a particular wilderness area, and the relevant federal land management agency’s regulations governing wilderness areas. Section 4 of the act prohibits the construction of temporary roads or structures, as well as the use of motor vehicles, motorized equipment, and other forms of mechanical transport in wilderness areas, unless such construction or use is necessary to meet the minimum requirements for administration of the area, including for emergencies involving health and safety. Generally, the land management agencies have regulations that address the emergency and administrative use of motorized equipment and installations in the wilderness areas they manage. For example, under Fish and Wildlife Service regulations, the agency may authorize Border Patrol to use a wilderness area and prescribe conditions under which motorized equipment, structures, and installations may be used to protect the wilderness, including emergencies involving damage to property and violations of laws. Endangered Species Act of 1973. The purpose of the Endangered Species Act is to conserve threatened and endangered species and the ecosystems upon which they depend. Under section 7 of the act, if Border Patrol or the land management agencies determine that an activity B order Patrol intends to authorize, fund, or carry out may affect an animal or plant species listed as threatened or endangered, it may initiate eithe informal or a formal consultation with the Fish and Wildlife Service— which we refer to as a section 7 consultation—to ensure that its actions do not jeopardize the continued existence of such species or result in the destruction or adverse modification of its critical habitat. The agencies are to initiate informal consultation if they determine that an activity may affect—but is not likely to adversely affect—a listed species or critical habitat. To help implement key federal land management laws, Border Patrol and the land management agencies have developed several mechanisms to coordinate their responsibilities, including a national-level memorandum of understanding and local agreements. The national-level memorandum of understanding was signed in 2006 by the secretaries of Homeland Security, the Interior, and Agriculture and is intended to provide consistent principles to guide the agencies’ activities on federal lands along the U.S. borders. Such activities may include information sharing; placing and installing surveillance equipment, such as towers and underground sensors; using roads; providing Border Patrol with natural and cultural resource training; mitigating environmental impacts; and pursuing suspected undocumented aliens off road in wilderness areas. The memorandum also contains several provisions for resolving conflicts between Border Patrol and land managers, such as directing the agencies to resolve conflicts and delegate resolution authority at the lowest field operations level possible and to cooperate with each other to complete— in an expedited manner—all compliance that is required by applicable federal laws. We found several instances where Border Patrol stations and land management agencies have coordinated their responsibilities through use of this national-level memorandum of understanding. For example, Border Patrol and land managers in Arizona used the 2006 memorandum of understanding to set the terms for reporting Border Patrol off-road vehicle incursions in Organ Pipe Cactus National Monument, as well as for developing strategies for interdicting undocumented aliens closer to the border in the Cabeza Prieta National Wildlife Refuge and facilitating Border Patrol access in the San Bernardino National Wildlife Refuge.