The board shall not repeal or amend or otherwise directly or indirectly modify an ordinance enacted pursuant to paragraph (d) of subsection 1 of NRS 377A.020 in such a manner as to impair an outstanding bond issued pursuant to this chapter, or other obligations incurred pursuant to this chapter, until all obligations for which revenue from the ordinance have been pledged or otherwise made payable from such revenues pursuant to this chapter have been discharged in full or provision for full payment and redemption has been made.