The legislative power of Guam shall extend to all rightful subjects of legislation not inconsistent with the provisions of this chapter and the laws of the United States applicable to Guam. Taxes and assessments on property, internal revenues, sales, license fees, and royalties for franchises, privileges, and concessions may be imposed for purposes of the government of Guam as may be uniformly provided by the Legislature of Guam, and when necessary to anticipate taxes and revenues, bonds and other obligations may be issued by the government of Guam: Provided, however, That no public indebtedness of Guam shall be authorized or allowed in excess of 10 per centum of the aggregate tax valuation of the property in Guam. Bonds or other obligations of the government of Guam payable solely from revenues derived from any public improvement or undertaking shall not be considered public indebtedness of Guam within the meaning of this section. All bonds issued by the government of Guam or by its authority shall be exempt, as to principal and interest, from taxation by the Government of the United States or by the government of Guam, or by any State or Territory or any political subdivision thereof, or by the District of Columbia. The Secretary of the Interior (hereafter in this section referred to as “Secretary”) is authorized to guarantee for purchase by the Federal Financing Bank bonds or other obligations of the Guam Power Authority maturing on or before December 31, 1978, which shall be issued in order to refinance short-term notes due or existing on June 1, 1976 and other indebtedness not evidenced by bonds or notes in an aggregate amount of not more than $36 million, and such bank, in addition to its other powers, is authorized to purchase, receive or otherwise acquire these same. The interest rate on obligations purchased by the Federal Financing Bank shall be not less than a rate determined by the Secretary of the Treasury taking into consideration the current average market yield on outstanding marketable obligations of the United States of comparable maturities, adjusted to the nearest one-eighth of 1 per centum, plus 1 per centum per annum. The Secretary, with the concurrence of the Secretary of the Treasury, may extend the guarantee provision of the previous sentence until December 31, 1980. The Secretary, upon determining that the Guam Power Authority is unable to refinance on reasonable terms the obligations purchased by the Federal Financing Bank under the fifth sentence of this section by December 31, 1980, may, with the concurrence of the Secretary of the Treasury, guarantee for purchase by the Federal Financing Bank; and such bank is authorized to purchase, obligations of the Guam Power Authority issued to refinance the principal amount of the obligations guaranteed under the fifth sentence of this section. The obligations that refinance such principal amount shall mature not later than December 31, 1990, and shall bear interest at a rate determined in accordance with section
2285 of title
12. At the request of the Board of Directors of the Guam Power Authority for a second refinancing agreement and conditioned on the approval of the Government of Guam pursuant to the law of Guam, and conditioned on the establishment of an independent rate-making authority by the Government of Guam, the Secretary may guarantee for purchase by the Federal Financing Bank, on or before December 31, 1984, according to an agreement that shall provide for—
the Federal Financing Bank shall purchase such Guam Power Authority obligations if such Guam Power Authority obligations are issued to refinance the principal amount scheduled to mature on December 31, 1990. Should such second refinancing occur,