The most important element of operating an on-line analysis system is the ability to maintain on-site monitoring station all the year round as well as to guarantee the quality of data products. During the past five years, Centennial Technology has been responsible for the operation and management of automated water quality monitoring station constructed by Korean government. The operation of on-site monitoring station is viewed as an integral part of ensuring data quality. Centennial Technology successfully constructed own operating system that includes manager, system operator, operating chief, data quality manager, operator, reagent supplier, and analytical chemist.