Cal. Sts. & High. Code § 25322

The board of directors shall not adopt any resolution of completion until it obtains from the Director of Transportation a certificate in writing showing that the highway, or portion thereof, proposed to be surrendered to the county within which it is situated has been improved in accordance with the plans and specifications previously adopted therefor. Unless the highway, or portion thereof, has been improved under his supervision, the Director of Transportation shall not be required to furnish the certificate until the district engineer delivers his certificate to the Director of Transportation showing that the highway, or portion thereof, has been improved in accordance with the plans and specifications previously adopted.