Cal. EVID § 824

(a) Notwithstanding any other provision of this article, a just and equitable method of determining the value of nonprofit, special use property, as defined by Section 1235.155 of the Code of Civil Procedure, for which there is no relevant, comparable market, is the cost of purchasing land and the reasonable cost of making it suitable for the conduct of the same nonprofit, special use, together with the cost of constructing similar improvements. The method for determining compensation for improvements shall be as set forth in subdivision (b).

(b) Notwithstanding any other provision of this article, a witness providing opinion testimony on the value of nonprofit, special use property, as defined by Section 1235.155 of the Code of Civil Procedure, for which there is no relevant, comparable market, shall base his or her opinion on the value of reproducing the improvements without taking into consideration any depreciation or obsolescence of the improvements.

(c) This section does not apply to actions or proceedings commenced by a public entity or public utility to acquire real property or any interest in real property for the use of water, sewer, electricity, telephone, natural gas, or flood control facilities or rights-of-way where those acquisitions neither require removal or destruction of existing improvements, nor render the property unfit for the owner’s present or proposed use.