California Code, Revenue and Taxation Code - RTC § 435

(a) In preparing the assessment roll for the 1984-85 fiscal year and each fiscal year thereafter, the assessor shall use as the value of each parcel of timberland the appropriate site value pursuant to Section 434.5 plus the value, if any, attributable to existing, compatible, nonexclusive uses of the land. Assessments of values attributable to compatible uses determined in accordance with this part are subject to the appeals procedure established by law for other assessments.

(b) Nothing in this article shall prevent the assessor in valuing timberland from taking into consideration the existence of any mines, minerals, and quarries in or upon the land being valued, including, but not limited to, geothermal resources and oil, gas, and other hydrocarbon substances.

(c) The provisions of this article shall not apply to any structure on the land being valued or to an area of reasonable size used as a site for approved compatible uses.