California Code, Revenue and Taxation Code - RTC § 1630

(a) Any real property owner the use of whose land is subject to an enforceable restriction placed upon it by a local agency may apply to the governing body of the local agency for a written statement declaring the present intention of the governing body to refrain from removing or modifying any such restriction in the predictable future.

(b) The written statement of intention may be granted or denied by the governing body at its discretion. A reasonable fee not to exceed ten dollars ($10) may be charged for each such statement.

(c) The written statement may be presented to the county board of equalization as evidence that a restriction on the use of the taxpayer's land exists and that such restriction should be considered in assessing the value of the land.

(d) The written statement shall constitute a rebuttable presumption that the governing body does not intend to remove or modify the restriction in the predictable future.