Notwithstanding any provision of law to the contrary, no major water user shall convey water withdrawn or diverted from within the southeast Missouri regional water district created under section 256.643 when such withdrawal or diversion and subsequent conveyance to a location outside such district unduly interferes with the reasonable and customary activities of a major water user registered under section 256.410 located within such district. If such conveyance occurs, the attorney general or the party or parties affected may file an action for an injunction, however, in no case shall an injunction be issued if the injunction would be detrimental to public health or safety.