California Code, Streets and Highways Code - SHC § 2980

(a) As used in this division, the “true value of parcels” and the “true value of each parcel” means the fair market value of the land and improvements thereon, as determined by the legislative body. The determination of the legislative body shall be final and conclusive in the absence of fraud.

(b) The legislative body may determine that the fair market value of the land and improvements is their full cash value as defined by Article XIII A of the California Constitution and as shown upon the last equalized assessment roll of the county. However, this subdivision does not prevent the legislative body from determining fair market value by other reasonable means.