For the purpose of, but not limited to, retirement benefits, salary rates, seniority, and all fringe benefits, all time of employment with the San Bernardino County Air Pollution Control District immediately prior to employment with the Mojave Desert district, and any time of employment immediately prior thereto with the county, a county district, or both, whose authority, functions, and responsibilities have been assumed by the San Bernardino County Air Pollution Control District, shall be considered time of employment with the Mojave Desert district. Upon transfer to the Mojave Desert district, employees shall retain all their accumulated sick leave, vacation, and retirement benefits.