Transported deposit was accumulated in a grit chamber built at the mouth of Yeocheoncheon in 1987 with the intention of blocking the influx of sediment into the Ulsan-harbor. This study attempted to analyze the effects of the transported deposit on the water quality at Yeocheoncheon. Only one episode of dredging has been performed in the approximately 25 years since the grit chamber were built, leading to the formation of stagnant water in the grit chamber due to a large amount of transported deposit. The deposit has a relatively high organic content, in the range of 11.7-25.9% (mean 18.3%). It appears that the main reason for the upstream transport of water pollution from the mouth of the Yeocheoncheon is the tides. The effects of organic content and stagnant water on water quality were analyzed using WASP. Moreover, the changes in water quality arising due to the removal of the grit chamber were analyzed. Results indicated that BOD improved by 18.8-100%, while T-P improved by 90.0-617.4%, between the grit chamber and Hanbi-Gyo , which is located 1.3 km away from the grit chamber.

Abstract
 1. 서 론
 2. 재료 및 방법
  2.1. 침사지 및 여천천 현황
  2.2. 여천천의 수질현황 및 침사지내 퇴적도 조사
 3. 결과 및 고찰
  3.1. 조위영향에 따른 여천천 수질변화
  3.2. WASP 7 모델을 이용한 여천천 수질변화 예측
 4. 결 론
 REFERENCES

• 이상현(울산발전연구원 기획경영실, Planning & Administration Bureau, Ulsan Development Institute) | Sang-Hyeon Lee
• 조홍제(울산대학교 건설환경공학부, School of Civil & Environ. Engineering, University of Ulsan) | Hong-Je Cho Corresponding author