Mo. Rev. Stat. § 644.082

It shall be unlawful for any person to operate, use or maintain and discharge water contaminants from any water contaminant or point source or wastewater treatment plant unless he holds a permit from the commission. Any person violating this section shall be deemed guilty of a misdemeanor and shall be fined upon conviction at least one hundred dollars and not more than five hundred dollars and shall be required to apply for such a permit within thirty days.