Whenever a municipality or county commission, under the provisions of this article, decides to acquire, by purchase or otherwise, construct, establish, extend or equip a waterworks system or an electric power system, or to construct any additions, betterments, or improvements to any waterworks or electric power system, it shall cause an estimate to be made of the cost thereof, and may, by ordinance or order, provide for the issuance of revenue bonds under the provisions of this article, which ordinance or order shall set forth a brief description of the contemplated undertaking, the estimated cost thereof, the amount, rate or rates of interest, the time and place of payment and other details in connection with the issuance of the bonds. The bonds shall be in such form and shall be negotiated and sold in such manner and upon such terms as the governing body of such municipality or county commission may, by ordinance or order, specify. All the bonds and the interest thereon shall be exempt from all taxation by this state, or any county, municipality or county commission, political subdivision or agency thereof. Notwithstanding any other provision of this code to the contrary, the real and personal property which a municipality or county has acquired and constructed according to the provisions of this article, and any leasehold interest therein held by other persons, shall be considered public property and shall be exempt from taxation by the state, or any county, municipality or other levying body, so long as the same is owned by the municipality or county: Provided, That with respect to electric power systems, this exemption for real and personal property shall be applicable only for the real and personal property: (1) Physically situate within the municipal or county boundaries of the municipality or county which acquired or constructed the electric power system and there was in place prior to the effective date of the amendments to this section made in the year 1992 an agreement between the municipality and the county commission for payments in lieu of tax; or (2) acquired or constructed with the written agreement of the county school board, county commission, and any municipal authority within whose jurisdiction the electric power system is or is to be physically situate. Notwithstanding anything contained in this statute to the contrary, this exemption shall be applicable to any leasehold or similar interest held by persons other than a municipality or county only if acquired or constructed with the written agreement of the county school board, county commission and any municipal authority within whose jurisdiction the electric power system is or is to be physically situate: Provided, however, That payments made to any county commission, county school board or municipality in lieu of tax pursuant to such an agreement shall be distributed as if the payments resulted from ad valorem property taxation. The bonds shall bear interest at a rate per annum set by the municipality or county commission, payable at such times, and shall be payable as to principal at such times, not exceeding 50 years from their date, and at such place or places, within or without the state, as shall be prescribed in the ordinance or order providing for their issuance. Unless the governing body of the municipality or county commission shall otherwise determine, the ordinance or order shall also declare that a statutory mortgage lien shall exist upon the property so to be acquired, constructed, established, extended or equipped, fix minimum rates or charges for water or electricity to be collected prior to the payment of all of said bonds and shall pledge the revenues derived from the waterworks or electric power system for the purpose of paying the bonds and interest thereon, which pledge shall definitely fix and determine the amount of revenues which shall be necessary to be set apart and applied to the payment of the principal of and interest upon the bonds and the proportion of the balance of the revenues, which are to be set aside as a proper and adequate depreciation account, and the remainder shall be set aside for the reasonable and proper maintenance and operation thereof. The rates or charges to be charged for the services from the waterworks or electric power system shall be sufficient at all times to provide for the payment of interest upon all bonds and to create a sinking fund to pay the principal thereof as and when the same become due, and reasonable reserves therefor, and to provide for the repair, maintenance and operation of the waterworks or electric power system, and to provide an adequate depreciation fund, and to make any other payments which shall be required or provided for in the ordinance or order authorizing the issuance of said bonds: Provided further, That the notice given by the municipality or county commission for a change in rates or charges to be charged for the services from the waterworks or electric power system shall be provided by Class I legal advertisement in a newspaper of general circulation in its service territory not less than one week prior to the public hearing of the governing body of the municipality or the county commission required for the approval of the change in rates or charges.