No water shall be available for appropriation by storage in, or by direct diversion from, any of the components of the California Wild and Scenic Rivers System, as such system exists on January 1, 1981, where such appropriation is for export of water into another major hydrologic basin of the State, as defined in the Department of Water Resources Bulletin 160-74, unless such export is expressly authorized prior to such appropriation by: (a) an initiative statute approved by the electors, or (b) the Legislature, by statute passed in each house by roll call vote entered in the journal, two-thirds of the membership concurring.