36 CFR § 2.35 - Alcoholic beverages and controlled substances.
(a) Alcoholic beverages.
(2) The following are prohibited:
(i) The sale or gift of an alcoholic beverage to a person under 21 years of age, except where allowed by State law. In a State where a lower minimum age is established, that age limit will apply for purposes of this subparagraph.
(ii) The possession of an alcoholic beverage by a person under 21 years of age, except where allowed by State law. In a State where a lower minimum age is established, that age will apply for purposes of this subparagraph.
(i) The superintendent may close all or a portion of a public use area or public facility within a park area to the consumption of alcoholic beverages and/or to the possession of a bottle, can or other receptacle containing an alcoholic beverage that is open, or that has been opened, or whose seal is broken or the contents of which have been partially removed. Provided however, that such a closure may only be implemented following a determination made by the superintendent that:
(A) The consumption of an alcoholic beverage or the possession of an open container of an alcoholic beverage would be inappropriate considering other uses of the location and the purpose for which it is maintained or established; or
(B) Incidents of aberrant behavior related to the consumption of alcoholic beverages are of such magnitude that the diligent application of the authorities in this section and §§ 1.5 and 2.34 of this chapter, over a reasonable time period, does not alleviate the problem.
(iii) Violating a closure imposed pursuant to this section is prohibited.
(b) Controlled substances. The following are prohibited:
(1) The delivery of a controlled substance, except when distribution is made by a practitioner in accordance with applicable law. For the purposes of this paragraph, delivery means the actual, attempted or constructive transfer of a controlled substance whether or not there exists an agency relationship.
(2) The possession of a controlled substance, unless such substance was obtained by the possessor directly, or pursuant to a valid prescription or order, from a practitioner acting in the course of professional practice or otherwise allowed by Federal or State law.