The faith of the state is pledged that this article, any law supplemental or otherwise pertaining thereto, and any other law concerning the bonds or other district securities, taxes, assessments, or the pledged revenues, or any combination of such securities, such taxes, such assessments, and such revenues shall not be repealed, amended, or otherwise directly or indirectly modified in such a manner as to impair adversely any outstanding district securities, until all such securities have been discharged in full or provision for their payment and redemption has been fully made, including without limitation the known minimum yield from the investment or reinvestment of moneys pledged therefor in federal securities.
C.R.S. § 32-11-504