Previous evaluation of pollutant loads for the basin of Tokyo Bay are not accurately treated with the influence of flood-flow conditions. In the present study, we attempt to clarify the nutrients and COD loads in the main influent rivers under hydrologic events. For this purpose, we mounted automatic water samplers at the Edo, Ara, Tama and Naka Rivers. The observed results indicate that specific relations between river discharge Q and water quality are found in each river. The pollutant loads in the Ara and Naka Rivers are dominant in flood and low flow conditions, respectively. The large amount of the nutrients and COD loads were transported under flood flow conditions in all rivers.
