California Code, Streets and Highways Code - SHC § 25448

The treasurer of the district shall annually before the fifteenth day of August transmit to the several boards of supervisors within the funding district, a statement showing the amount to be raised in such year by the levy and collection of special assessment taxes upon the lands only, exclusive of improvements, within each county which is within the funding district and subject to be taxed for the payment of principal, interest and delinquencies upon any funding bonds of the district.  The statement shall show the percentages of the total amount to be levied upon the lands in each county in accordance with the zones established for each such funding district.  The engineer of the district shall cause to be prepared and filed in the office of the clerk of the board of supervisors of each county within the district, a map or plat showing the boundaries of the lands in each county which are within any funding district showing the boundaries of the zones therein and the percentage of the total assessment to be paid by each zone.