California Code, Water Code - WAT § 35520.6

Notwithstanding any other provision of this division, the board may determine to issue bonds secured by benefit assessments, in which event the board shall define and determine a drainage service area which may be the entire district or any lesser portion thereof that will be benefited by the project.

The service area shall be designated “Drainage Service Area No.__________ of __________ Water District.”  The service area may be subdivided by the board into separate zones or subareas that benefit solely from separate components of the total project.