36 C.F.R. § 71.4 – Posting.

(a) The administering bureaus of the Department of the Interior shall provide for the posting of the following designation sign at entrances to Designated Entrance Fee Areas and at appropriate locations in areas with Designated Recreation Use Facilities in such a manner that the visiting public will be clearly notified that Federal recreation fees are charged. The designation sign shall:
1. (1) Be constructed of enameled steel, coated aluminum, silk screen reflective materials attached to wood or metal, or other permanent materials;
2. (2) Consist of the basic elements, proportion, and color as indicated below:
  1. (i) The representation of an American Golden Eagle (colored gold) and a family group (colored midnight blue) enclosed within a circle (colored white with a midnight blue border) framed by a rounded triangle (colored gold with a midnight blue border).
    1. (A) The color midnight blue shall be Pantone Matching System 282; the color gold shall be Pantone Matching System 130;
    2. (B) The rounded triangle shall be 18 inches in vertical height at all Designated Entrance Fee Areas, except that at those areas accessible only on foot, the rounded triangle may be 9 inches vertical height;
  2. (ii) The words “U.S. Fee Area” as indicated below.
(b) Clear notice shall be posted by any bureau issuing special recreation permits at its area headquarters having administrative jurisdiction over the area in which the use authorized by such a permit is to occur, that fees are charged for such permits. In addition, any specialized recreation use authorized by permit shall, if reasonably feasible, be posted with the designation sign described in paragraph (a) of this section at the site of use at the time of use.
(c) Proportionally sized replicas of the designation sign described in paragraph (a) of this section may be used in conjunction with other signs erected by any bureau of the Department of the Interior which direct the public to Designated Entrance Fee Areas, Designated Recreation Use Facilities, or Special Recreation Permit Uses.
(d) No entrance fee for admission to any Designated Entrance Fee Area or recreation use fee for the use of any Designated Recreation Use Facility shall be collected unless such area or facility is posted in accordance with this section. No fee for any Special Recreation Permit Use shall be collected unless clear notice that such a fee is charged is posted at the area headquarters of the bureau issuing such permit in which the use authorized by the permit is to occur.