(a) Protection of the best usage as a source of potable water supply shall include standards and guidance values to protect the aesthetic quality of the water, including but not limited to taste, odor, and discoloration, both as a source of potable water and for other human uses such as clothes washing and showering. Such values are referred to as Aesthetic (Water Source) values and shall be derived based on an evaluation of reported levels of the substance that affect the aesthetic quality of the water. Values derived shall not exceed the value of a Specific MCL that is based on aesthetic considerations.

(b) Protection of the best usage of fishing shall include standards and guidance values to prevent tainting of aquatic food, including but not limited to taste, odor, and discoloration. Such values are referred to as Aesthetic (Food Source) values and derived based on an evaluation of reported levels of the substance that affect the aesthetic quality of the fish flesh, aquatic life, wildlife, or livestock that are consumed by humans and that acquire such flavor, odor, or color because of habitation in, passage through, or ingestion of waters.

(c) If the available data are deemed insufficient for deriving a value based on subdivision (a) or (b) of this section, a value may be established based on chemical correlation to a chemical for which a standard or guidance value has been established pursuant to that subdivision, if similar aesthetic considerations are anticipated because of similarity of functional groups or metabolic or toxicologic pathways.