A district may petition the Director of Environment and Energy to remove the director’s designation of the area as a management area or the requirement of an action plan for a management area or to modify the boundaries of a management area designated pursuant to section 46-725. If the director determines that the level of contamination in a management area has stabilized at or been reduced to a level which is not detrimental to beneficial uses of ground water, he or she may remove the designation or action plan requirement or modify the boundaries of the management area.