Cal. Water Code § 36560

Assessments that are imposed pursuant to this part and Part 7.5 (commencing with Section 37200) to pay the principal of, and interest on, general obligation bonds of a district or which are issued by a district for an improvement district are ad valorem taxes that are imposed in accordance with subdivision (b) of Section 1 of Article XIIIA of the California Constitution and are not, therefore, subject to the procedures and approval process of Article XIIID of the California Constitution. This section shall not be construed as declaring that any other type of assessment is either exempt from, or subject to, the procedures and approval process of Article XIIID of the California Constitution.