16 U.S.C. § 8546

(a) Monitoring The Secretary concerned shall monitor each recreation service provider issued a special recreation permit for compliance with the terms of the permit— (1) not less than annually or as frequently as needed (as determined by the Secretary concerned), in the case of a temporary special recreation permit for outfitting and guiding issued under section 8545 of this title ; and (2) not less than once every 2 years or as frequently as needed (as determined by the Secretary concerned), in the case of a special recreation permit described in paragraph (13)(A)(iv)(I) of section 6801 of this title (as amended by this title) that is issued for a term of not more than 10 years. (b) Use-of-allocation reviews (1) In general If the Secretary of Agriculture, acting through the Chief of the Forest Service, or the Secretary, as applicable, allocates visitor-use days among special recreation permits for outfitting and guiding, the Secretary of Agriculture, acting through the Chief of the Forest Service, shall, and the Secretary may, review the use by the recreation service provider of the visitor-use days allocated under a long-term special recreation permit described in paragraph (13)(A)(iv)(I) of section 6801 of this title (as amended by this title), once every 5 years. (2) Requirements of the review In conducting a review under paragraph (1), the Secretary concerned shall determine— (A) the number of visitor-use days that the recreation service provider used each year under the special recreation permit, in accordance with paragraph (3); and (B) the year in which the recreation service provider used the most visitor-use days under the special recreation permit. (3) Consideration of surrendered, unused visitor-use days For the purposes of determining the number of visitor-use days a recreation service provider used in a specified year under paragraph (2)(A), the Secretary of Agriculture, acting through the Chief of the Forest Service, and the Secretary, as applicable, shall consider an unused visitor-use day that has been surrendered under section 8542(c)(1)(B) of this title as— (A) 1/2 of a visitor-use day used; or (B) 1 visitor-use day used, if the Secretary concerned determines the use of the allocated visitor-use day had been or will be prevented by a circumstance beyond the control of the recreation service provider.