For the purpose of maintaining and operating such flood control works as shall be constructed by the United States army corps of engineers or other agency of the United States government, when the same shall have been completed and turned over to the county and to pay a portion of the principal and interest on bonds issued under the authority of Kan. Stat. Ann. § 12-1774, and amendments thereto, by cities located in the county, the board of county commissioners of such county shall be empowered to make an annual tax levy upon all of the taxable tangible property within the county. It shall be the duty of the board of county commissioners and the county engineer to keep all such flood control works in serviceable condition and to make such repairs as, from time to time, may be necessary.