Temporal increase of SS induces concentrations in various forms of organic matter including BOD, COD, TOC. Consequently, it causes hard to identify sources of water pollution during or after precipitation. The objective of this study is to investigate variations of DOC concentration caused by increase of flow and changes of external factors in river by comparing to SS concentration. In results, monitoring sites (e.g., Banbyeonchen) consisting of hard riverbed showed high correlation between SS and organic matters, except BOD. On the contrary, other sites (e.g., Naesungcheon) where riverbed consists of sand were found in a wide range of annual fluctuation in SS level, whereas these sites showed a narrow range in annual DOC fluctuation. In Gumhogang and Namgang, a lower correlation between SS and other factors was found most likely because of high concentration in organic matter. However, lower annual fluctuation values of DOC were observed in comparison to those of COD and TOC. Similar results were also confirmed in main river sites, Sangju and Mulgeum. In conclusion, DOC concentration is better indicator for monitoring organic matter which cannot be provided by BOD, COD, TOC in the Nakdong river basin.