(Added by Ordinance No. 148986, effective January 26, 1980.) The Washington County Water Supply Bonded Debt Service Sinking Fund is hereby created. Water revenues in the form of contributions from other water purveyors and the City of Portland shall be placed in this Fund and expended only for duly authorized payments of principal and interest for bonds issued for the purpose of constructing a water supply line to Washington County. Upon payment of all principal and interest of said bond issue, any balance remaining in this Fund shall be returned, on a prorated basis, to the contributors and this Fund shall be discontinued.