16 U.S.C. § 6810: Volunteers

(a) Authority to use volunteersThe Secretary may use volunteers, as appropriate, to collect recreation fees and sell recreation passes. (b) Waiver or discount of fees; site-specific agency passIn exchange for volunteer services, the Secretary may waive or discount an entrance fee, standard amenity recreation fee, or an expanded amenity recreation fee that would otherwise apply to the volunteer or issue to the volunteer a site-specific agency pass authorized under section 6804(c) of this title. (c) National Parks and Federal Recreational Lands PassIn accordance with the guidelines issued under section 6804(a)(7) of this title, the Secretaries may issue a National Parks and Federal Recreational Lands Pass to a volunteer in exchange for significant volunteer services performed by the volunteer. (d) Regional multientity passesThe Secretary may issue a regional multientity pass authorized under section 6804(d) of this title to a volunteer in exchange for significant volunteer services performed by the volunteer, if the regional multientity pass agreement under which the regional multientity pass was established provides for the issuance of the pass to volunteers.