At the time bonds are issued pursuant to § 34-10-16 the trustees shall by resolution provide for the levy of an irrepealable tax upon all of the property within the hospital district for the years and in the amounts, sufficient to pay the principal and interest when due, without limitations as to rate or amount and it shall be the duty of the board or boards of county commissioners to cause the levy to be made each year until the bonds are fully paid. All moneys received from the levies shall be used only for the retirement of bonds until the same are fully paid.
SDCL 34-10-21