Any tract of land included within the boundaries of any such district, at or after its organization under the provisions of this act, may be excluded therefrom, in the manner herein prescribed, but such exclusion of land from the district shall not impair or affect its organization, or its rights in or to property or any of its rights or privileges of whatever kind or nature; nor shall such exclusion affect, impair or discharge any contract, obligation, lien or charge for or upon which the district or the land so excluded is liable or chargeable, at the time such land is excluded from the district.