Abstract
As an investigation of environment of enclosed coastal seas, we attempted the estimation of the permissible load of COD considering the internal production. COD was separated to pollution by inflow load and pollution by internal production, and on COD pollution by inflow load, the load curve was deduced from the material balance which made the bay to be one box. In addition, it was shown that it was possible to estimate the permissible load on COD, by giving the transformation coefficients from total nitrogen or total phosphorus on the internal production of COD proposed by Nakanishi et al. These results of the study can contribute to the proposition of the water quality improvement plan according to the characteristics of the bay.
