50 C.F.R. § 25.53
Establishment of single visit entrance fees
Entrance fees established for single visit permits at a designated Entrance Fee Area shall consider the following criteria with regard to the local area within which the refuge is located:
(a) The direct and indirect cost to the Government.
(b) The benefits to the permit holder.
(c) The public policy or interest served.
(d) The comparable fees charged by non-Federal public agencies.
(e) The economic and administrative feasibility of fee collection.