Mo. Rev. Stat. § 640.423: Designation as protection area removed, when.

The department shall determine when the level of a contaminant or contaminants in a special water quality protection area does not exceed, and are not likely to exceed, the water quality standards established pursuant to sections 640.400 to 640.435 and this chapter and chapter 644. Upon such determination, the designation of an area as a special water quality protection area pursuant to section 192.300, sections 640.100, 640.120, and 640.400 to 640.435 shall be removed.