The FLPMA §1701 et seq., 'established a policy in favor of retaining public lands for multiple use management.' 'Multiple use management' is a deceptively simple term that describes the enormously complicated task of striking a balance among the many competing uses to which land can be put, including, but not limited to, recreation, range, timber, minerals, watershed, wildlife and fish, and [uses serving] natural scenic, scientific and historical values. A second management goal, 'sustained yield,' requires BLM to control depleting uses over time, so as to ensure a high level of valuable uses in the future. The designation of a wilderness area can be made only by Act of Congress, see 43 U.S.C. § 1782(b). Pursuant to § 1782, the Secretary of the Interior has identified so-called 'wilderness study areas' (WSAs), roadless lands of 5,000 acres or more that possess 'wilderness characteristics,' as determined in the Secretary's land inventory. Of 3.3 million acres in Utah that had been identified for study, 2 million were recommended as suitable for wilderness designation. Until Congress acts one way or the other, FLPMA provides that 'the Secretary shall continue to manage such lands . . . in a manner so as not to impair the suitability of such areas for preservation as wilderness.' 43 U.S.C. § 1782(c). This nonimpairment mandate applies to all WSAs identified under § 1782, including lands considered unsuitable by the Secretary. The main tool that BLM employs to balance wilderness protection against other uses is a land use plan called a 'resource management plan.' Generally, a land use plan describes, for a particular area, allowable uses, goals for future condition of the land, and specific next steps. Protection of wilderness has come into increasing conflict with off-road vehicles. The use of ORVs on federal land has negative environmental consequences, including soil disruption and compaction, harassment of animals, and annoyance of wilderness lovers. Thus, BLM faces a classic land use dilemma of sharply inconsistent uses in a context of scarce resources and congressional silence with respect to wilderness designation. P filed this action against D. P seeks declaratory and injunctive relief for BLM's failure to act to protect public lands in Utah from damage caused by ORV use. P claims that D violated its nonimpairment obligation under § 1782(a) by allowing degradation in certain WSAs; that BLM had failed to implement provisions in its land use plans relating to ORV use; and that BLM had failed to take a 'hard look' at whether pursuant to the National Environmental Policy Act of 1969 (NEPA). P claims it can sue to remedy these three failures to act pursuant to the APA's provision of a cause of action to 'compel agency action unlawfully withheld or unreasonably delayed.' 5 U.S.C. § 706(1). The District Court dismissed the suit. The Tenth Circuit reversed. The majority acknowledged that under § 706(1), 'federal courts may order agencies to act only where the agency fails to carry out a mandatory, nondiscretionary duty.' It concluded, however, that BLM's nonimpairment obligation was just such a duty, and therefore BLM could be compelled to comply. The Supreme Court granted certiorari.