Any county, city, or town in the state of Washington which now has or may hereafter have an outstanding indebtedness evidenced by warrants or bonds, including warrants or bonds of any county, city, or town which are special fund obligations of and constitute a lien upon the waterworks or other public utilities of such county, city, or town, and are payable only from the income or funds derived or to be derived therefrom, whether issued originally within the limitations of the Constitution of this state, or of any law thereof, or whether such outstanding indebtedness has been or may hereafter be validated or legalized in the manner prescribed by law, may, by its corporate authorities, provide by ordinance or resolution for the issuance of funding bonds with which to take up and cancel such outstanding indebtedness in the manner hereinafter described, said bonds to constitute general obligations of such county, city, or town: PROVIDED, That special fund obligations payable only from the income funds of the public utility, shall not be refunded by the issuance of general municipal bonds where voter approval is required before general municipal bonds may be issued for such public utility purposes, unless such general municipal bonds shall have been previously authorized. Nothing in this chapter shall be so construed as to prevent any such county, city, or town from funding its indebtedness as now provided by law.