Step increases in rate of pay shall not be automatic upon completion of a specific period of service, but are based upon satisfactory performance, as reviewed by the department head. Annual review of employee performance should be made prior to March 1st of each year. This review shall be made to determine eligibility for increase in rate of pay to the next higher step within the established range for the grade, such increase to be approved by the assembly, to be effective as of July 1st of the calendar year in which the personnel review is conducted.