Mo. Rev. Stat. § 252.210: Contamination of streams — penalty.

It shall be unlawful for any person to cause any deleterious substance to be placed, run or drained into any of the waters of this state in quantities sufficient to injure, stupefy or kill fish which may inhabit the same at or below the point where any substance was thrown, run or drained into such waters; provided that it shall not be a violation of this section for any person engaged in industry, to cause or permit any water subject to his control or used in any branch of such industry to be so discharged under such precautionary measures as have been specifically approved by the commission. Any person violating any of the provisions of this section shall be deemed guilty of a misdemeanor.