California Code, Water Code - WAT § 75411

The resolution of the board shall also designate that portion of the cost of the project, if any, that the board determines can be secured equitably by means of an assessment on all lands in the district, or if so determined by the board, on all real property within the district, in accordance with the assessed value of the land (or real property) as it appears on the county assessment roll, payable in not to exceed 40 annual installments at an annual rate not to exceed 7 percent.

In lieu of securing such portion of the cost through a separate assessment levied on the land (or real property), the board may elect to pay such portion of the cost from funds secured for general purposes by assessments levied on all of the land within the district pursuant to the provisions of Chapters 1 (commencing with Section 75350) and 2 (commencing with Section 75370) of this part and subject to the limitations contained therein.  If the board so elects, it shall so state in the resolution and the amount of money so paid shall not be considered by the electors in the election provided in this chapter.