Cal. Rev. & Tax. Code § 5062

If any public land is heretofore or hereafter assessed and the taxes are not paid, the board of supervisors shall order the auditor to cancel the assessment if:

(a)Verified application is made by the owner of the land, and

(b)The applicant files with the board of supervisors a certificate of the Register of the United States Lands Office, or of the State Lands Commission, showing that the assessee or his successor in interest never received a patent or otherwise acquired title to the land.