In the case of any district described in Section 20560.1, and for purposes of financing costs of maintenance and operation on a temporary basis, repair to or replacement of damage caused by, or costs incurred as a result of, fire, flood, drought, earthquake, sabotage or acts of God, or preliminary or developmental work except for preliminary or developmental work on the Tuolumne River or its tributaries above the New Don Pedro Reservoir, in connection with works or facilities described in Section 20560.1, the district may borrow money by the issuance of notes or other evidences of indebtedness payable either from the revenue of the district or from the proceeds of sale of any authorized but unissued revenue bonds of the district, as the board may determine. Authorized but unissued revenue bonds of the district which have been approved by a vote of the electorate may only be issued for those purposes authorized by the electorate. The notes or other evidences of indebtedness shall be authorized by resolution of the board and may be issued without the necessity of calling and holding an election in the district. The notes or other evidences of indebtedness authorized under this section shall mature in not to exceed seven years from their date, may be sold either at public or private sale, and shall bear interest at such rate or rates and shall be sold at such price or prices as shall result in interest costs not exceeding such limits as may be determined by the board. The interest rates may be fixed or variable and shall not exceed 17 percent per annum. All other terms and conditions of such notes or other evidences of indebtedness shall be determined in accordance with the authorizing resolution. The notes or other evidences of indebtedness may be issued as part of a tax-exempt commercial paper program or other short-term note financing program. The district may arrange for the use of bank letters of credit or bank lines of credit for any purpose for which the notes or other evidences of indebtedness may be issued, as well as to provide additional sources of repayment for the notes or other evidences of indebtedness issued under this section. The maximum principal amount of notes or other evidences of indebtedness outstanding under this section, including the amounts drawn on available bank letters of credit or bank lines of credit, shall not at any one time exceed (1) twenty-five million dollars ($25,000,000) or 25 percent of the district’s annual gross revenues from the generation, transmission, distribution, and sale of electric power during its preceding fiscal year, whichever is greater, when payable from the revenues of the district; or (2) the principal amount of any authorized but unissued revenue bonds of the district, not to exceed twenty-five million dollars ($25,000,000), when payable from the proceeds of sale of such authorized but unissued revenue bonds. The notes or other evidences of indebtedness shall be legal investments for all trust funds, for the funds of all insurance companies, commercial banks, savings banks, trust companies, the state school funds, and for any funds which may be invested in bonds of cities, cities and counties, counties, school districts, or municipalities in the state.