Ariz. Rev. Stat. § 35-468.05
This state pledges to and agrees with the holders of the bonds that this state will not limit, alter or impair the rights vested in any political subdivision under this article to receive the monies, including water transportation revenues or an equivalent source, necessary to produce sufficient revenue to fulfill the terms of any agreements made with the holders of the bonds, or in any way impair the rights and remedies of the bondholders, until all bonds issued under this article, together with interest, including interest on any unpaid installments of interest, and all costs and expenses in connection with any action or proceedings by or on behalf of the bondholders are fully met and discharged. The political subdivision may include this pledge and undertaking in its resolutions and indentures securing its bonds under this article.
A.R.S. § 35-468.05