The general assembly may authorize the contracting of an indebtedness on behalf of the state of Missouri and the issuance of bonds or other evidences of indebtedness not exceeding in the aggregate the sum of one hundred fifty million dollars for the purpose of providing funds for use in this state for the protection of the environment through the control of water pollution. The bonds shall be issued by the state board of fund commissioners from time to time and in such amounts as may be necessary to carry on a program by the water pollution board of the state as determined by the general assembly for the planning, financing and constructing sewage treatment facilities by any county, municipality, sewer district, or any combination of the same and the board of fund commissioners shall offer such bonds at public sale, and shall provide such method as it may deem necessary for the advertisement of the sale of each issue of said bonds before the same are sold.

The proceeds of the sale or sales of any bonds issued hereunder shall be paid into the state treasury and be credited to a fund to be designated the “Water Pollution Control Fund”.

The bonds shall be retired serially and by installments within a period not to exceed twenty-five years from their date of issue and shall bear interest at a rate or rates not exceeding the rate permitted by law.

The proceeds of the sale of the bonds herein authorized shall be expended for the purposes for which the bonds are hereinabove authorized to be issued.

The bonds and the interest thereon shall be paid out of the “Water Pollution Control Bond and Interest Fund”, which is hereby created, and the payment of said bonds and the interest thereon shall be secured by a pledge of the full faith, credit and resources of the state of Missouri. Upon the issuance of such bonds, or any portion thereof, the state board of fund commissioners shall notify the state comptroller of the amount of money required, in the remaining portion of the fiscal year during which said bonds shall have been issued, for the payment of interest on the said bonds, and of the amount of money required for the payment of interest on the said bonds in the next succeeding fiscal year, and to pay said bonds as they mature. Thereafter, within thirty days after the beginning of each fiscal year, the state board of fund commissioners shall notify the state comptroller of the amount of money required for the payment of interest on the said bonds in the next succeeding fiscal year and to pay said bonds maturing in such next succeeding fiscal year.

It shall be the duty of the state comptroller to transfer, at least monthly, from the state revenue fund, after deducting therefrom the proportionate part thereof appropriated for the support of the free public schools, and to credit to the water pollution control bond and interest fund such sum as may be necessary from time to time until there shall have been transferred to said fund the amount so certified to him by the state board of fund commissioners, as hereinabove provided.

If at any time after the issuance of any of the said bonds, it shall become apparent to the state comptroller that the funds available in the state revenue fund, as aforesaid, will not be sufficient for the payment of the sinking fund and interest on outstanding obligations of the state and for the purpose of public education and the principal and interest maturing and accruing on said bonds during the next succeeding fiscal year, a direct tax shall be levied upon all taxable tangible property in the state for the payment of said bonds and the interest that will accrue thereon. In such event, it shall be the duty of the state comptroller annually, on or before the first day of July, to determine the rate of taxation necessary to be levied upon all taxable tangible property within the state to raise the amount of money needed to pay the principal of and interest on such bonds maturing and accruing in the next succeeding fiscal year, taking into consideration available funds, delinquencies and costs of collection. The state comptroller shall annually certify the rate of taxation so determined to the county clerk of each county and to the comptroller or other officer in the city of St. Louis whose duty it shall be to make up and certify the tax books wherein are extended the ad valorem state taxes. It shall be the duty of said clerks and the said comptroller or other proper officer in the city of St. Louis to extend upon the tax books the taxes to be collected and to certify the same to the collectors of the revenue of their respective counties and of the city of St. Louis, who shall collect such taxes at the same time and in the same manner and by the same means as are now or may hereafter be provided by law for the collection of state and county taxes, and to pay the same into the state treasury for the credit of the water pollution control bond and interest fund.

All funds paid into the water pollution control bond and interest fund shall be and stand appropriated without legislative action to the payment of principal and interest of the said bonds, there to remain until paid out in discharge of the principal of said bonds and the interest accruing thereon, and no part of such fund shall be used for any other purpose so long as any of the principal of said bonds and the interest thereon shall be unpaid.

The general assembly may enact such laws as may be necessary to carry this amendment into effect.