The Board of Supervisors may amend this chapter by the following procedure. The Board of Supervisors at any regular or special meeting of the Board of Supervisors may, by a majority vote, pass a resolution stating its intent to amend this chapter. A written copy of the resolution, stating the wording of the amendment and the purpose of the amendment and the date of the meeting scheduled to act on the amendment shall be delivered to the legislative branches of each municipality and mailed or left at the usual place of residence of each member of the Board of Supervisors at least 30 calendar days prior to the meeting scheduled to adopt the amendment. The amendment shall become effective after 30 calendar days following a two-thirds vote of the Board of Supervisors at the meeting scheduled to act on the amendment, unless a majority of the legislative branches of member municipalities requests, in writing, that the Board of Supervisors hold a special District meeting to vote on the amendment. Upon adoption by the Board of Supervisors or approval of the voters, the amendment shall be submitted and acted on by the General Assembly in accordance with the provisions of 17 V.S.A. § 2645. The amendment shall become effective upon affirmative enactment of the proposal, either as proposed or as amended by the General Assembly. For the purposes of this section, this chapter shall be considered a municipal charter. This chapter may be amended from time to time in the manner herein provided, but no such amendment shall be made which shall substantially impair the rights of the holders of any bonds or other notes or other evidence of indebtedness or substantially affect any obligations under long-term contracts of the District then outstanding or in effect, or the rights of the District to procure the means for payment, continuation, or termination thereof.