Wat. Code, § 35950.5

If the issuance of bonds has been authorized previously by the district or by the district for an improvement district and the change or supplement to the plan of works has increased the original estimate of cost, the board may provide for and call a special bond election within the district or the improvement district to submit to the voters of the district or the improvement district a proposition of whether or not additional indebtedness shall be incurred and bonds issued therefor in an amount which, when added to the amount of unissued bonds previously authorized to accomplish the original plan of works, will not exceed the revised estimate of cost set forth in the resolution approving the change or supplement to the plan of works. Said proposition need only refer to the amended plan, state the amount of additional bonds to be authorized, and indicate that previously authorized bonds will be issued to carry out the amended plan. Said proposition need not state the amount of unissued bonds previously authorized. In any such instance, the special bond election provided for herein shall be called, noticed, held, conducted and the results thereof canvassed in substantially the same manner as provided for in this division for bond elections.