The federal government owns roughly 640 million acres, more than a quarter of the land in the United States. These lands are heavily concentrated in 12 western states (including Alaska), where t he federal government owns roughly half of the overall land area. Four federal agencies—the National Park Service (NPS), Fish and Wildlife Service (FWS), and Bureau of Land Management (BLM), all in the Department of the Interior (DOI), and the U.S. Forest Service (FS) in the Department of Agriculture—administer about 95% of those lands. No single law provides authority for these four agencies to acquire and/or disposal of lands. Rather, Congress provided various acquisition and disposal authorities through laws enacted over more than a century. This report describes the primary authorities of the four agencies. The extent to which each of the agencies has authority to acquire and dispose of land, and the nature of the authorities, varies considerably. Some of the agencies have relatively broad authority to acquire and/or dispose of land. Most notably, the BLM has relatively broad authority for both acquisitions and disposals. By contrast, the NPS has no general authority to acquire land to create new park units or to dispose of park lands. The extent of the acquisition and disposal authorities for the FS and the FWS are not nearly as broad as the BLM's but not nearly as restrictive as the NPS's. The FS authority to acquire lands is mostly limited to lands within or contiguous to the boundaries of a national forest. The agency has various authorities to dispose of land, but they are relatively constrained and infrequently used. The FWS has various authorities to acquire lands but no general authority to dispose of its lands. The acquisition authorities differ as to the circumstances in which they apply, and the disposal authorities likewise differ as to their purposes. Thus, where a specific acquisition or disposal by an agency is contemplated, the particular authority at issue should be consulted. In general, the acquisition authorities are designed to allow federal agencies to acquire lands that could be viewed as benefitting from federal management. Among other circumstances, acquisition might be authorized to bring inholdings or lands adjacent to federal lands into federal ownership to improve or simplify management of federal lands. Acquisitions also might be authorized to conserve species, protect natural and cultural resources, and increase opportunities for recreation. The disposal authorities generally are designed to allow federal agencies to dispose of land that is no longer required for a federal purpose, might be inefficient to manage, or might be chiefly valuable for another purpose. For instance, disposal might be authorized to allow lands to be used for agriculture, community development, mineral extraction, or educational purposes. Agencies also acquire and dispose of federal land in exchanges. Exchanges are not discussed separately in this report, as often the authorities to acquire and dispose of lands also apply to land exchange. However, there are provisions of law particularly applicable to exchanges. The exchange authorities for the NPS and the FWS are relatively narrow. The Federal Land Policy and Management Act of 1976 (FLPMA; 43 U.S.C. §§1701-1781) provides broader exchange authority and is the main authority governing exchanges by the BLM and the FS. Congress often faces questions on the adequacy of existing acquisition and disposal authorities; the nature, extent, and location of their use; the extent of federal land ownership overall; and the sources and levels of land acquisition funds, among other issues. The suitability of the acquisition and disposal authorities, and the extent and circumstances of their use by the agencies, forms the backdrop for congressional consideration of measures to establish, modify, or eliminate the use of authorities. With regard to the establishment of new authorities, for instance, some 115 th Congress proposals would authorize states to exchange land grant parcels for federal lands. Other measures would authorize the BLM and FS to convey small tracts to adjacent landowners and to govern the use of proceeds from these conveyances. Proposals to modify authorities include measures in the 115 th Congress to reauthorize and amend BLM authority to sell or exchange land under the Federal Land Transaction Facilitation Act (FLTFA; 43 U.S.C. §§2301 et seq.), as well as bills to amend the Small Tracts Act (16 U.S.C. §521e) regarding the type and value of FS lands that can be disposed of and the use of related proceeds. Among the provisions to eliminate the use of authorities are those to prevent the disposal of federal land under the General Mining Law of 1872, which have been contained in annual Interior appropriations laws since FY1995. In addition, Congress frequently considers legislation authorizing and governing the acquisition or disposal of specific parcels. For example, Title XXX of P.L. 113-291 contained various provisions to authorize the acquisition and/or disposal of land. Congress may consider such legislation to provide an agency with acquisition or disposal authority in a particular instance because it is lacking. In other cases, Congress directs a particular acquisition or disposal to facilitate the action. For instance, the legislation may seek to direct an acquisition based on Congress's assessment of public needs and priorities. It may expedite the process for acquiring a parcel of land, such as by limiting the assessments and evaluations that ordinarily would be required under law. The legislation also might authorize actions not ordinarily permitted, such as the conveyance of land at reduced or no cost rather than at fair market value. Congress also addresses acquisition and disposal policy in the context of deliberations on the role and goals of the federal government in owning and managing land generally. The extent to which the federal government should own land remains controversial. Many westerners contend that there is excessive federal influence over their lives and economies and that the federal government should divest itself of many lands. Many others support the policy of retaining lands in federal ownership on behalf of the public and sometimes advocate adding more lands to enhance protection. Recent Congresses considered diverse bills pertaining to the extent of federal land ownership. Among others, 115 th Congress measures would authorize or direct the Secretary of the Interior and the Secretary of Agriculture to offer to sell a certain percentage of land in each of several fiscal years. Other bills provide that where a land management agency acquires land, an equal number of acres is to be offered for sale. Another set of issues pertains to the sources and levels of funds for land acquisition. The principal financing mechanism for federal land acquisition is discretionary appropriations under the Land and Water Conservation Fund (LWCF). Provisions of the Land and Water Conservation Fund Act of 1965 (LWCF Act; 54 U.S.C. §§200301 et seq.) had provided for $900 million in specified revenues to be deposited in the LWCF annually. These provisions expired September 30, 2018. Each year, Congress determines the level of appropriations from the LWCF for federal land acquisition. Total appropriations for land acquisition and the amount provided to each of the federal land management agencies have varied substantially since the program's origin in 1965. In the 115 th Congress, some measures propose permanent reauthorization of the LWCF and/or mandatory appropriations at the authorized level. Advocates of such bills typically seek stable, predictable funding to promote a strong federal role in acquiring and managing sensitive resources. Other measures would direct a portion of funding to particular purposes, such as acquisitions in areas with restricted access for fishing, hunting, and other types of recreation. Still other proposals would allow LWCF to be used for a broader array of purposes, including nonacquisition purposes, due to concerns about the extent of federal land ownership and the availability of funding for other federal activities. Additional sources of funding are available for some agencies or under certain authorities. For instance, the FWS has a mandatory source of funds for land acquisition through the Migratory Bird Conservation Fund, as discussed below. As another example, the BLM also has mandatory spending authorities that allow the agency to keep the proceeds of land sales and use these proceeds for subsequent acquisitions and other purposes. These authorities are discussed below. The application of mandatory spending authorities, including the uses of the proceeds, has been the subject of congressional debate. As noted above, various laws authorizing and governing specific land acquisitions have been enacted. In addition, the four federal land management agencies have different standing authorities for acquiring lands. In general, all four agencies are authorized to accept land as gifts and bequests. In addition, each generally is authorized to use eminent domain —taking private property, through condemnation, for public use—while compensating the landowner. However, this practice is controversial, and it is rarely used by the land management agencies. The primary land acquisition authorities are described below for each of the four federal land management agencies. In general, the agencies are presented in the order of the breadth of their authorities, with the NPS (the narrowest authorities) first and the BLM (the broadest authorities) last. The NPS does not have standing authority to acquire lands for new or existing units of the National Park System, except in limited circumstances. Rather, most units have been created by Congress, and the law creating a park unit typically includes specific authority for the NPS to acquire nonfederal inholdings within the identified boundaries of that park. The Secretary of the Interior is authorized to make certain boundary adjustments of park units for "proper preservation, protection, interpretation, or management" and to acquire the nonfederal lands within the adjusted boundary, under specified provisions and conditions (54 U.S.C. §100506(c)). Some of these conditions have been interpreted to apply particularly to boundary adjustments requiring land purchases, as opposed to those in which added lands are acquired by donation, transfer, or exchange. The President has authority to create national monuments on federal lands under the Antiquities Act of 1906 (54 U.S.C. §§320301 et seq.). In total, 158 monuments have been created by presidential proclamation. Most are managed by the NPS, but some are managed by the BLM and other agencies. Under law, the Secretary of the Interior and the NPS have responsibilities related to the potential acquisition of lands for the National Park System. Among other requirements, the Secretary is directed "to investigate, study, and continually monitor the welfare of" areas that could potentially be added to the system and to report to Congress on possible additions (54 U.S.C. §100507). Furthermore, the general management plan for each unit is to include potential changes to the boundaries of the unit and the reasons for such changes (54 U.S.C. §100502). The Secretary also is to conduct a "systematic and comprehensive review of certain aspects of the National Park System" and to submit a related report to Congress at least every three years (54 U.S.C. §100505(a)) that includes a list of all authorized but unacquired lands within the boundaries of park units and a priority listing of these unacquired parcels (54 U.S.C. §100505(c)). The Secretary of Agriculture has various authorities to acquire lands for the National Forest System (NFS). The NFS consists of 284 units covering 232.4 million acres of federal and nonfederal land, including national forests, national grasslands, purchase units, land utilization projects, and other areas. Today, only an act of Congress can create new NFS units, but the Secretary may acquire lands within or contiguous to the proclaimed exterior boundaries of an NFS unit. The NFS contains substantial acreage of nonfederal lands within the proclaimed boundaries of the system, particularly in the east, where national forests were established after extensive settlement. NFS units in the Eastern and Southern Regions average about 46% nonfederal land within their boundaries, while Western Region NFS units average about 10%. The FS has very limited regulatory authority over the uses of the 39.5 million acres of nonfederal land within the NFS. The FS's primary land acquisition authority is the Weeks Act of 1911 (16 U.S.C. §515), which was used to acquire many of the lands that became the eastern national forests. The Weeks Act authority continues to be the agency's primary authority to acquire lands; however, acquisitions are now limited to lands within (or adjacent to) established NFS unit boundaries. The Weeks Act also authorizes the Secretary to modify the NFS unit boundary as needed to encompass new acquisitions. Other laws authorize the FS to acquire lands for the national forests, typically in specific areas or for specific purposes. For example, Section 205 of the Federal Land Policy and Management Act (FLPMA; P.L. 94-579 ) authorizes the acquisition of access corridors—including easements—to national forests across nonfederal lands (43 U.S.C. §1715(a)). Another example is the Act of August 3, 1956 (7 U.S.C. §428(a)), which authorizes the FS to acquire lands without any geographical limitations but does require a provision be made in a specific appropriation or other law. Another law authorizes proceeds from certain land sales or exchanges to be used for acquisitions, including for administrative sites and enhancement of recreational access. However, the acquisitions are limited to the state in which FS previously conveyed NFS land under specific disposal authorities, as discussed later in this report. Several other acquisition authorities apply to specific national forests, such as the Act of June 11, 1940, which authorizes the purchase of lands within the Angeles National Forest in California. In addition, the Secretary of Agriculture and the secretary of a military department that has lands within or adjacent to proclaimed NFS land may interchange lands, without reimbursement or transfer of funds. Many of the acquisition authorities also allow the FS to accept donations of land as specified. Within the NFS, the Secretary of Agriculture also is authorized to acquire privately owned lands within or adjacent to designated wilderness areas (16 U.S.C. §1134(c)), Wild and Scenic River corridors (16 U.S.C. §1277), and certain segments of designated National Trails (16 U.S.C. §1244), as specified by the law creating the trail. Lands may be added to the National Wildlife Refuge System (NWRS) in a number of ways, including through congressional and administrative actions and donations. A principal FWS land acquisition authority is the Migratory Bird Conservation Act of 1929 (MBCA; 16 U.S.C. §§715 et seq.). This act authorizes the Secretary of the Interior to recommend areas "necessary for the conservation of migratory birds" to the Migratory Bird Conservation Commission, after consulting with the relevant governor (or state agency) and appropriate local government officials (16 U.S.C. §715a and §715c). In addition, the state in which the purchase is located must have consented to the acquisition by law (16 U.S.C. §715f and §715k-5). The Secretary may then purchase or rent areas or interests therein approved by the commission and acquire by gift or devise any area or interest therein (16 U.S.C. §715d). The MBCA authority is used frequently because of the availability of funding through the Migratory Bird Conservation Fund (MBCF, 16 U.S.C. §718d). The MBCF is supported by multiple sources of funding, including three major sources: the sale of hunting and conservation stamps (commonly known as duck stamps); import duties on arms and ammunition; and a portion of certain refuge entrance fees. MBCF funds are permanently appropriated to the extent of receipts and, after paying certain administrative costs, may be used for the "location, ascertainment, and acquisition of suitable areas for migratory bird refuges ..." (16 U.S.C. §718d(b)). The predictability of funding and permanent authority for use makes the MBCF, and thus the MBCA, particularly important for FWS land acquisition and unique among the four agencies. Other laws provide general authority to expand the NWRS, including the Fish and Wildlife Coordination Act of 1934 (16 U.S.C. §§661-667a), the Fish and Wildlife Act of 1956 (16 U.S.C. §§742a et seq.), and the Endangered Species Act of 1973 (16 U.S.C. §§1531-1544). The National Wildlife Refuge System Administration Act of 1966 (16 U.S.C. §§668dd-668ee) authorizes the Secretary of the Interior to acquire land or interests therein through donated funds or exchange (16 U.S.C. §668dd(b)). Further, FLPMA authorizes the Secretary of the Interior to withdraw lands from the public domain for creating or adding to refuges (which would be an interagency transfer), although withdrawals exceeding 5,000 acres are subject to congressional approval (43 U.S.C. §1714(c)). In contrast to NPS and FS land acquisition, where the lands generally must be within the boundaries of established units, the FWS can acquire new lands to create a new refuge or to expand an existing one under the general FWS authorities cited above, as well as under certain other laws. Some national wildlife refuge (NWR) units have been created by specific acts of Congress, such as Protection Island NWR (WA) and Bayou Sauvage Urban NWR (LA) (16 U.S.C. §668dd note). Units also can be created by executive order; for example, the Midway Atoll NWR was created by President Clinton in Executive Order 13022. The BLM has broad, general authority to acquire lands, principally under Section 205 of FLPMA. Specifically, the Secretary of the Interior is authorized to acquire, by purchase, exchange, donation, or use of eminent domain, lands or interests therein (43 U.S.C. §1715(a)). The BLM acquires land or interests in land, including inholdings, for a variety of reasons. These include to protect natural and cultural resources, to increase opportunities for public access and recreation, and to improve management of lands. As noted above, various laws directing the disposal of particular lands sometimes have been enacted. In addition, the four federal land management agencies have different standing authorities for disposing of lands. The specific disposal authorities are discussed below for each of the four agencies in the order of their apparent breadth, with the NPS (the narrowest authorities) first and the BLM (the broadest authorities) last. The NPS does not have general authority to dispose of National Park System lands. Units and lands of the Park System that were established by acts of Congress can be disposed of only by acts of Congress. Preservation of park units is a management goal and provisions of law limit the power of the Secretary of the Interior to dispose of land in changing park boundaries. Although the Secretary can, under specified conditions, make boundary changes that concurrently add and remove land within the boundary, minor boundary revisions solely to remove NPS acreage can be made only by Congress. Also, the Secretary can acquire by exchange lands that are adjacent to a boundary revision, but the Secretary cannot dispose of NPS land to do so (54 U.S.C. §100506(c)). Presidents have modified the boundaries of national monuments established by previous presidential proclamations, in some cases reducing the size of the monument. However, no president has terminated a monument established by proclamation. The FWS does not have general authority to dispose of its lands. With certain exceptions, wildlife refuge lands administered by the FWS can be disposed only by an act of Congress (16 U.S.C. §§668dd(a)(5) and (6)). For refuge lands reserved from the public domain, FLPMA prohibits the Secretary of the Interior from modifying or revoking any withdrawal which added lands to the NWRS (43 U.S.C. §1714(j)). For acquired lands, disposal is allowed only if: (1) the disposal is part of an authorized land exchange (16 U.S.C. §§668dd(a)(6) and (b)(3)); or (2) the Secretary determines the lands are no longer needed and the Migratory Bird Conservation Commission approves the disposal (16 U.S.C. §668dd(a)(5)). In the latter case, the disposal must recover the acquisition cost or be at the fair market value (whichever is higher), and the receipts must be deposited in the Migratory Bird Conservation Fund. The Secretary of Agriculture has numerous authorities to convey lands within proclaimed NFS boundaries out of federal ownership—through sale or exchange—although previous, broader authorities have been modified or revoked. Many of the authorities put constraints on land disposal, such as applying only to a specific geographical area or to the disposal of particular administrative properties or facilities. Many of the authorities are used in conjunction with FLPMA and other federal law and as such may place requirements on the sale or exchange of land. This includes obtaining at least fair market value for the sale of federal lands; requiring that nonfederal land exchanged for federal land be in the same state; and requiring exchanged lands to be of equal value, although value may be partially equalized with a cash payment (43 U.S.C. §1716). The General Exchange Act of 1922 (16 U.S.C. §485) authorizes the exchange of NFS land or timber that was reserved from the public domain if the Secretary determines it will be in the public interest. The nonfederal land must be within the same state and within the exterior boundary of a national forest, and it must be chiefly valuable for national forest purposes, among other provisions. The Weeks Act of 1911 allows for similar exchanges for acquired NFS lands (16 U.S.C. §516). The 1983 Small Tracts Act authorizes the Secretary to dispose of NFS land by sale or exchange, generally up to certain specified acreage limits. The disposal may be To improve management efficiencies where NFS lands are interspersed with nonfederal mineral rights owners, or if the Secretary determines the parcels to be inaccessible, physically isolated from other federal land, or to have lost national forest character (40 acres maximum); To relieve encroachments including due to erroneous surveys, or encroachments by a permanent habitable improvement if there is no evidence that the encroachment was intentional or due to negligence (10 acres maximum); To dispose of unneeded federal rights-of-way substantially surrounded by nonfederal lands (no specified acreage limitation); and If the parcel is used as a cemetery, landfill, or sewage plant pursuant to a special use authorization for the use and occupancy of NFS land (no specified acreage limitation) (16 U.S.C. §521e). The conveyance must be determined to be in the public interest and the tracts may not be valued at more than $500,000. The land can be disposed of for cash, lands, interests in land (such as an easement), or any combination thereof for at least the value of the land being sold or exchanged (16 U.S.C. §521d) plus "all reasonable costs of administration, survey, and appraisal incidental to such conveyance" (16 U.S.C. §521f). In some cases, the proceeds may be used for specified land acquisition purposes. The 1958 Townsites Act authorizes the Secretary to transfer up to 640 acres of NFS land adjacent to communities in Alaska or the 11 western states for townsites, if the "indigenous community objectives ... outweigh the public objectives and values which would be served by maintaining such tract in Federal ownership" (16 U.S.C. §478a). Public notice of the application for such transfer is required, and upon a "satisfactory showing of need," the Secretary may offer the land to a local governmental entity at "not less than the fair market value." The Education Land Grant Act, also known as the Sisk Act (16 U.S.C. §479a), authorizes the Secretary to transfer up to 80 acres of NFS land for a nominal cost upon written application of a public school district. It provides for reversion of the title to the federal government if the lands are not used for the educational purposes for which they were acquired. There are a few other specific authorities that allow for the disposal of NFS lands. For example, the 1911 Weeks Act authorizes the disposal of NFS lands that are "chiefly valuable for agriculture" but were acquired inadvertently or otherwise, if agricultural use will not injure the forests or streamflows and the lands are not needed for public purposes. The lands can be sold as homesteads in parcels of up to 80 acres (16 U.S.C. §519). The Bankhead-Jones Farm Tenant Act of 1937 (7 U.S.C. §§1010-1012) also authorizes the disposal of lands acquired under its authority, although the FS has adopted regulations stating that the Bankhead-Jones lands comprising the national grasslands will be held permanently (36 C.F.R. §213.1(b)). The BLM can dispose of land under several authorities. They include (1) exchanges and sales under FLPMA, (2) sales or exchanges under the FLTFA, (3) transfers to other governmental units or nonprofit entities for public purposes, (4) patents under the General Mining Law of 1872, and (5) geographically limited sale authorities. With regard to exchanges under FLPMA, the exchanges must serve the public interest, and the federal and nonfederal lands in the exchange must be located in the same state and be of equal value (with cash equalization payments possible), among other requirements (43 U.S.C. §1716). With regard to sales under FLPMA, the BLM is authorized to sell certain tracts of public land that are identified through the land-use planning process. Such tracts must meet specific criteria (43 U.S.C. §1713(a)): (1) such tract because of its location or other characteristics is difficult and uneconomic to manage as part of the public lands, and is not suitable for management by another Federal department or agency; or (2) such tract was acquired for a specific purpose and the tract is no longer required for that or any other Federal purpose; or (3) disposal of such tract will serve important public objectives, including but not limited to, expansion of communities and economic development, which cannot be achieved prudently or feasibly on land other than public land and which outweigh other public objectives and values, including, but not limited to, recreation and scenic values, which would be served by maintaining such tract in Federal ownership. The size of the tracts for sale is determined by "the land use capabilities and development requirements." Proposals to sell tracts of more than 2,500 acres first must be submitted to Congress and can be disapproved by Congress. Lands may not be sold at less than their fair market value. They generally must be sold through competitive bidding, although modified competition and noncompetitive sales are allowed. FLTFA provides for the sale or exchange of BLM lands identified for disposal under BLM land- use plans. The law create s a separate Treasury account for most of the proceeds (96%) from the sale or exchange, and it provide s for the use of those funds by the Secretary of the Interior and the Secretary of Agriculture. The Secretaries may acquire nonfederal lands, specifically inholdings , lands adjacent to federal lands that contain exceptional resources , and areas adjacent to inaccessible lands that are open to recreation. Up to 20% of the funds in the account may be used for administrative costs, and at least 80% of the funds for acquisition are to be in the state in which the funds are generated . The Recreation and Public Purposes Act (43 U.S.C. §869) authorizes the Secretary, upon application by a qualified applicant, to dispose of any public lands to a State, Territory, county, municipality, or other State, Territorial, or Federal instrumentality or political subdivision for any public purposes, or to a nonprofit corporation or nonprofit association for any recreational or any public purpose consistent with its articles of incorporation or other creating authority. The lands can be sold or leased, and the act specifies conditions, qualifications, and acreage limitations for transfer. The price of the land depends on the type of entity that will receive it, for instance, whether a state government or a nonprofit organization. The price also depends on the intended use of the land, with some sales and leases made at no cost. Although the BLM can dispose of lands through patents under the General Mining Law of 1872, since FY1995 a series of annual moratoria on issuing mineral patents has been enacted into law. These moratoria, contained in the annual Interior appropriations laws, have effectively prevented this means of federal land disposal. Specifically, the Mining Law allows access to and development of hardrock minerals on federal lands that have not been withdrawn from entry. With evidence of valuable minerals and sufficient developmental effort, the Mining Law allows mining claims to be patented, with full title (of surface and mineral rights) transferred to the claimant upon payment of the appropriate fee. Nonmineral lands used for associated milling or other processing operations can also be patented (30 U.S.C. §42). Patented lands may be used for purposes other than mineral development. The BLM also has geographically limited land sale authorities. The program with the largest revenue stream has been the Southern Nevada Public Land Management Act of 1998, which allows the Secretary of the Interior to sell or exchange certain lands around Las Vegas. The BLM and the local government unit jointly decide on the lands to be offered for sale or exchange. In general, 85% of the proceeds are deposited into a special account, and are available to the Secretary of the Interior for land acquisition in Nevada and other purposes in the state, such as certain capital improvements and development of parks, trails, and natural areas. The other 15% of the proceeds are for state or local purposes, specifically the State of Nevada General Education Fund (5%) and the Southern Nevada Water Authority (10%). Other provisions of law similarly provide for BLM land sales in particular areas (mostly in Nevada), with specific allocations of the proceeds. Further, the BLM continues to dispose of land in Alaska as required by law, such as through transfers to the state of Alaska and to Alaska native corporations. A total of about 150 million acres in Alaska will be transferred from federal to state and private ownership. 

Answer: The federal government owns roughly 640 million acres, heavily concentrated in 12 western states. Four agencies—the National Park Service (NPS), Fish and Wildlife Service (FWS), and Bureau of Land Management (BLM) in the Department of the Interior, and the U.S. Forest Service (FS) in the Department of Agriculture—administer about 95% of those lands. The extent to which each of these four federal agencies have authority to acquire and dispose of land varies considerably. The BLM has relatively broad authority for both acquisitions and disposals under the Federal Land Policy and Management Act of 1976 (FLPMA). The agency also has other authorities for disposing of land, including two laws that allow the agency to retain the proceeds for subsequent land acquisition, among other purposes, and a law that allows transfers to governmental units and other entities for public purposes. By contrast, the NPS has no general authority to acquire land to create new park units or to dispose of park lands. The FS authority to acquire lands is mostly limited to lands within or contiguous to the boundaries of a national forest. The agency has various authorities to dispose of land, but they are relatively constrained and infrequently used. The FWS has various authorities to acquire lands but no general authority to dispose of its lands. The agency frequently uses acquisition authority under the Migratory Bird Conservation Act of 1929 because of the availability of funding through the Migratory Bird Conservation Fund. The nature of the acquisition and disposal authorities of the four federal agencies also varies. In general, the acquisition authorities are designed to allow the four agencies to bring into federal ownership lands that many contend could benefit from federal management. Disposal authorities generally are designed to allow agencies to convey land that is no longer needed for a federal purpose or that might be chiefly valuable for another purpose. Some of the authorities specify particular circumstances where they can be used, such as the conveyance of FS land for educational purposes and the disposal of BLM land for recreation and public purposes. Congress often faces questions on the adequacy of existing acquisition and disposal authorities; the nature, extent, and location of their use; and the extent of federal land ownership overall. The current acquisition and disposal authorities form the backdrop for consideration of measures to establish, modify, or eliminate authorities, or to provide for the acquisition or disposal of particular lands. In some cases, Congress enacts bills to provide authority to acquire or dispose of particular parcels where no standing authority exists and, in other cases, to direct or facilitate land transactions. Congress also addresses acquisition and disposal policy in the context of debates on the role and goals of the federal government in owning and managing land generally, and it has considered broader measures to dispose of lands or to promote acquisition. Other issues for Congress pertain to the sources and levels of funds for land acquisition. The Land and Water Conservation Fund (LWCF) is the primary source of funding for land acquisition. Congress has considered diverse measures related to the LWCF, such as legislation to make LWCF funding permanent and bills to direct LWCF monies to additional, nonacquisition purposes. Additionally, the FWS has the Migratory Bird Conservation Fund, an account with mandatory spending authority supported by revenue from three sources. The BLM also has mandatory spending authorities that allow the proceeds from land sales to be used for land acquisition, among other purposes.