Cal. Sts. & Hy. Code § 5843
Notice of the hearing on the resolution shall be given to the persons within the existing maintenance district in the manner prescribed by Section 5838. Mailed notice shall be required with respect to additional improvements for a lighting maintenance district where the annual cost to such district of such additional improvements is more than two thousand five hundred dollars ($2,500). At the hearing the board of supervisors shall hear and pass upon any and all protests to the maintaining and operating of such additional improvements by the existing maintenance district and its decision shall be final and conclusive. At the conclusion of the hearing the board of supervisors may by order, entered upon its minutes, make the expenses of maintaining and operating such additional improvements a charge upon the existing maintenance district.
Ca. Sts. and High. Code § 5843