(1) A board of highway district commissioners shall enter upon its records an order determining the net proportionate share of the indebtedness of the highway district incurred prior to a detachment of territory for which the detached territory should be and remain liable.
(2)  Notwithstanding the detachment of territory with respect to the future operations and conduct of the district, the board of highway district commissioners shall annually levy upon all the property within the detached territory a special tax sufficient to pay as it falls due, the principal and interest of that proportionate share of the prior indebtedness of the district for which the detached territory is and shall remain liable. The special tax shall be levied at the same time, certified, and collected in the same manner as are the other taxes levied by the district, but after detachment the detached territory or the property in the district shall not be subject to taxation by a highway district for future operations of the district or for the repayment of any indebtedness subsequently incurred by the district.