California Code, Government Code - GOV § 27770

(a) A chief probation officer shall be appointed in every county. He or she shall be nominated by the juvenile justice commission or regional juvenile justice commission of the county in the same manner as the presiding judge, in a county with two judges, or a majority of the judges, in a county with more than two judges, shall prescribe, and shall thereafter be appointed by the presiding judge or majority of judges. The salary for the position shall be established by the board of supervisors of the county. He or she may be removed for good cause as determined by the presiding judge or majority of judges.

(b) In counties with charters that provide for appointment and tenure of office for the chief probation officer, the provisions of the charter shall control as to those matters and, in counties that have established or hereafter establish merit or civil service systems governing the methods of appointment and the tenure for the chief probation officer, the provisions of the merit or civil service systems shall control as to those matters. In all other counties, appointment and tenure of the chief probation officer shall be controlled exclusively by the provisions of this code.