85-7-205. Duty of trustees, levy, and indebtedness. The board of trustees may develop the source of supply; clean, improve, and develop the channel of the stream; and do and perform other work on the main distributing system as will be beneficial to the better distribution of the waters of the decreed water right stream and may cover the expenses of such work by levy. Whenever waters of the stream under the irrigation district created by this part are commingled with other waters or it is difficult to determine how many acres are irrigable by the water rights held in the stream, the acre basis of levy shall be determined by the number of cubic feet of water per second owned by such party or parties at the rate of .025 cubic feet of water per second to the acre. The board may not issue bonds or incur any indebtedness other than warrant indebtedness under the limitations imposed by law.