Mo. Rev. Stat. § 256.415

Any unregistered diversion of water by a major water user is hereby declared to be a nuisance and the director may request the attorney general to file an action in the name of the state for an injunction to stop all water withdrawal or diversion from a water source; provided, however, that any person withdrawing or diverting from a water source may continue to withdraw or divert from that water source while such action is pending. The issuing court shall dissolve the injunction issued under this section when the person files a current registration with the division.