Cal. Gov't Code § 56126
Upon request by the executive officer or the clerk of any county or district, the assessor of any city, county, or district shall furnish estimated assessed valuations, determined by the same methods and valuations used in preparing the last equalized assessment roll, in both of the following cases:
(b) Where a single assessment parcel shown on the last equalized assessment roll either:
(2) Overlaps two or more counties, cities, districts, or election precincts, or any combination of those entities or precincts.
Any of these estimates shall be conclusively presumed to be assessed values for the purpose of this division, but shall be given no force or effect for other purposes.