Cal. Health & Saf. Code § 6550.8
At the conclusion of the hearing, if the proceedings are not terminated pursuant to Section 6550.7, the district board shall by resolution determine whether it is deemed necessary to form the improvement district and to undertake the project and, if so, the amount of any proposed debt to be incurred to finance the project, that the exterior boundaries of the portion of the district which will be benefited are set forth on a map on file with the district board (which map shall govern for all details as to the extent of the improvement district), and that such portion of the district set forth on such map shall thereupon constitute and be known as "Improvement District No. __ of ____ (name of sanitary district)," and the determination made in said resolution shall be final and conclusive. After the formation of such improvement district within a sanitary district, all proceedings for the purpose of any bond election for the project for which the improvement district was formed shall be limited and shall apply only to such improvement district, and taxes for the payment of such bonds and the interest thereon, shall be derived exclusively from an annual tax upon the taxable property in such improvement district.
Ca. Health and Saf. Code § 6550.8