Such tax shall be paid as is provided in Iowa Code Chapter 423A, and the proceeds of such tax shall be used for the purposes stated in subsection 4 thereof, as follows:
“4. The revenue derived from any hotel and motel tax authorized by this chapter shall be used as follows:
a. Each county or city which levies the tax shall spend at least fifty percent of the revenues derived therefrom for the acquisition of sites for, or constructing, improving, enlarging, equipping, repairing, operating, or maintaining of recreation, convention, cultural, or entertainment facilities including but not limited to memorial buildings, halls and monuments, civic center convention buildings, auditoriums, coliseums, and parking areas or facilities located at those recreation, convention, cultural, or entertainment facilities or the payment of principal and interest, when due, on bonds or other evidence of indebtedness issued by the county or city for those recreation, convention, cultural, or entertainment facilities; or for the promotion and encouragement of tourist and convention business in the city or county and surrounding areas.
b. The remaining revenues may be spent by the city or county which levies the tax for any city or county operations authorized by law as a proper purpose for the expenditure within statutory limitations of city or county revenues derived from ad valorem taxes.
c. Any city or county which levies and collects the hotel and motel tax authorized by this chapter may pledge irrevocably an amount of the revenues derived therefrom for each of the years the bonds remain outstanding to the payment of bonds which the city or county may issue for one or more of the purposes set forth in paragraph ‘a’ of this subsection. Any revenue pledged to the payment of such bonds may be credited to the spending requirement of paragraph ‘a’ of this subsection.”