The study monitored irrigation water quality along Dong-Jin river watershed from 1994 to 1998. Water quality was best in July and August due to rainwater dilution, but worse in April. Inorganic components were higher at Jeong-up and Won-pyeong stream, likely due to sewage water and narrow width. Overall, water quality improved from 1995 to 1998, especially at Jeong-up stream. Cation and anion levels were highest in April and at Jeong-up stream. Cation ratio was higher in May and lower at Won-pyeong stream. Most inorganic components were correlated with each other, but not with organic components like COD.