Notwithstanding any extension of time of any recordable contract as provided in section
390ii
(e) of this title, lands under recordable contract shall be eligible to receive irrigation water at less than full cost for a period not to exceed ten years from the date such recordable contract was executed by the Secretary in the case of contracts existing prior to October 12, 1982, or five years from the date such recordable contract was executed by the Secretary in the case of contracts entered into subsequent to October 12, 1982, or the time specified in section
390rr of this title for lands described in that section: Provided, That in no case shall the right to receive water at less than full cost under this subsection terminate sooner than eighteen months after the date on which the Secretary again commences the processing or the approval of the disposition of such lands.