Tenn. Code Ann. § 69-5-604

The county mayor shall be chair of the board of directors, and the board shall elect one (1) of the other directors secretary and treasurer of the board, who, as treasurer, shall give bond in the sum of twenty-five thousand dollars ($25,000) to faithfully account for all money coming into the treasurer's hands, the bond to be approved by the county legislative body and payable to the county or state, for the use of the district, and to be recorded in the drainage record.