California Code, Welfare and Institutions Code - WIC § 755

Any person placed on probation by the juvenile court or adjudged to be a ward of the juvenile court may be permitted by order of the court to reside in a county other than the county of his legal residence, and the court shall retain jurisdiction over such person.

Whenever a ward of the juvenile court is permitted to reside in a county other than the county of his legal residence, he may be placed under the supervision of the probation officer of the county of actual residence, with the consent of such probation officer. The ward shall comply with the instructions of such probation officer and upon failure to do so shall be returned to the county of his legal residence for further hearing and order of the court.