The Yocheon is an upper stream of Sumjin river, passing through Namwon city. The water temperature of the stream increases from upper stream to downstream. The amount of COD, T-P, T-N, EC, TDS abruptly increases at measuring site 8. Whereas, the pH and DO level abruptly decreases at this site. At this point, the Yocheon river joins another small stream passing through the central part of Namwon city. At a further downstream pass site 8, the amount of COD on April and June (a dry season) is on third grade of water quality for lacustrine. This contamination suggests that sewage from the Namwon city provide COD, T-N, T-P into the stream. At point 2, the high amount of T-N indicates that the upper stream is contaminated by agricultural activity.