CA Gov't Code Section 31000.5

The board of supervisors may employ technical assistants for the assessor to enable him to secure the necessary maps and plats for the performance of his work. The board may employ such technical assistants, either exclusively for the county or may enter into agreements for the employment of such persons with the board or boards of supervisors of one or more other counties. The agreement may provide that contributions from the treasuries of the respective counties may be made for the purpose of paying the compensation and expenses of such technical assistants, and the amounts or percentages to be paid by each county. The agreement may be continued for a definite term or until rescinded and may provide for the method of rescission by any of the contracting counties.