16 U.S. Code § 6810 - Volunteers
The Secretary may use volunteers, as appropriate, to collect recreation fees and sell recreation passes.
In 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.
In 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.
The 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.
Section 6804 of this title, referred to in subsecs. (b) to (d), was in the original a reference to section 5, and was translated as meaning section 805 of title VIII of div. J of Pub. L. 108–447, to reflect the probable intent of Congress.