Cal. Sts. & High. Code § 6420

After the full expiration of 30 days from the date of the recordation of the warrant, and after the filing of the written statement of all payments received by the contractor or his assignees upon the assessment, the street superintendent shall make and certify to the treasurer a complete list of all assessments unpaid, which amount to one hundred fifty dollars ($150) or over, upon any assessment or diagram number.