Whenever any indebtedness has been incurred by a district authorized to levy and collect ad valorem taxes, it shall be lawful for the board to levy taxes and collect revenue for the purpose of creating a reserve fund in such amount as the board may determine, which may be used to meet the obligations of the district, for maintenance and operating charges and depreciation, and provide extensions of and betterments to the improvements of the district.
Idaho Code § 67-4917