Cal. Wat. Code § 46500
The assessment list of each county shall remain open for payment in the office of the county treasurer of the affected counties for a period of 30 days and shall continue to remain open thereafter until such time, if ever, as the board makes an order calling a special election for the issuance of bonds to be secured by the assessment or until such time as the board files with the county treasurer a resolution, adopted and approved in accordance with Section 45102, authorizing the issuance of bonds to be secured by the assessment. If the result of the election, if any is called, is that the proposal to issue bonds is defeated, or if no bonds are issued within six months after such a resolution has been so filed, the assessment list shall again become open.
Ca. Water Code § 46500