36 CFR § 21.3
Use of thermal water
November 4, 2020
(a) The use of the thermal waters of Hot Springs National Park, for purposes other than those authorized by the Superintendent, is prohibited.
(b) The heating, reheating, or otherwise increasing the temperature of the thermal waters of Hot Springs National Park is prohibited.
(c) The introduction of any substance, chemical, or other material or solution into the thermal waters of Hot Springs National Park, except as may be prescribed by a physician for a bather or as may be directed by the Superintendent, is prohibited.