Cal. Wat. Code § 26625.1
If in the Madera Irrigation District, the county assessment roll reflects assessed value based on the California Land Conservation Act of 1965 (Williamson Act), (Chapter 7 (commencing with Section 51200) of Part 1 of Division 1 of Title 5 of the Government Code) for any parcel, then, upon the request of the Madera Irrigation District, such parcel shall also be assessed by the county assessor pursuant to Section 401 of the Revenue and Taxation Code. The assessed value for such parcel thus determined shall be entered on a supplemental assessment roll for district assessment purposes only and shall be used by the assessor for district assessments. The Madera Irrigation District shall reimburse the county for any increased cost incurred in making such additional assessment.
Ca. Water Code § 26625.1