Indebtedness of an interstate district shall be a general obligation of the district and shall be a joint and several general obligation of each member district, except that such obligations of the district and its member districts shall not be deemed indebtedness of any member district for the purposes of determining its borrowing capacity under Maine or New Hampshire law. A member district which withdraws from an interstate district shall remain liable for indebtedness of the interstate district which is outstanding at the time of withdrawal and shall be responsible for paying its share of such indebtedness to the same extent as though it had not withdrawn. [PL 1981, c. 693, §§ 5, 8 (NEW).]