For any new or revised sewer general comprehensive plan submitted by a water-sewer district for review under this chapter, the appropriate state agency shall review and either approve, conditionally approve, reject, or request amendments within ninety days of the receipt of the submission of the plan. The appropriate state agency may extend this ninety-day time limitation for new submittals by up to an additional ninety days if insufficient time exists to adequately review the general comprehensive plan. For rejections of plans or extensions of the timeline, the appropriate state agency shall provide in writing to the water-sewer district the reason for such action. In addition, the governing body of the water-sewer district and the appropriate state agency may mutually agree to an extension of the deadlines contained in this section.