California Code, Public Utilities Code - PUC § 90547

The board shall, on or before the first weekday in September, or if such weekday falls upon a holiday then on the first business day thereafter, fix the rate of taxes, designating the number of cents or fractions thereof upon each hundred dollars, using as a basis the value of property transmitted to the board by the county assessor, which rate of taxation shall be sufficient to raise the amount previously fixed by the board, subject to a maximum limitation of five cents ($0.05) per one hundred dollars ($100) assessed valuation.  These acts by the board shall constitute a value assessment of the property and a valid levy of the taxes so fixed.