The work on the eutropication of Youngsan river was conducted from Jul. 1997 to Jun. 1998. The value of water temperature in the study area varied from $4^{circ}C;to;32^{circ}C$ with an annual mean of $17.5^{circ}C$. DO varied from 4.0 $mg/{ell}$ to 13.5 $mg/{ell}$, with an annual mean 10.2 $mg/{ell}$,. BOD varied from 0.8 $mg/{ell}$, to 6.4 $mg/{ell}$ with an annual mean 3.1 $mg/{ell}$. COD varied from 4.6 $mg/{ell}$, to 9.0 $mg/{ell}$ with an annual mean 6.38 $mg/{ell}$. Nitrate varied from 1.58 $mg/{ell}$, to 6.77 $mg/{ell}$, with an annual mean of 3.475 $mg/{ell}$, Total-nitrogen varied from 2.14 $mg/{ell}$ to 8.38 $mg/{ell}$ with an annual mean of 5.083 $mg/{ell}$. Total-phosphate varied from 0.035 $mg/{ell}$ to 0.588 $mg/{ell}$ with an annual mean of 0.128 $mg/{ell}$. Chl.a varied from 1.8 ${mu}g/{ell}$ to 75.0 ${mu}g/{ell}$ with an annual mean of 19.55 ${mu}g/{ell}$. The euthrophic state index of $Carlson^{16)}$ were showed 61.8(TP) and 71(SD) value