38573d6e_International_Joint_Commission__Delisting_Guideline
[BUI] DEGRADATION OF AESTHETICS [Listing Guideline] When any substance in water produces a persistent objectionable deposit, unnatural color or turbidity, or unnatural odor (e.g. oil slick, surface scum). [Delisting Guideline] 
When the waters are devoid of any substance which produces a persistent objectional deposit, unnatural color or turbidity, or unnatural odor (e.g. oil slick, surface scum).
International Joint Commission
Delisting Guideline