Dissolved metals were analyzed after filtrating the water sample using an Advantec membrane filter with a pore size of 1 mm. Artificialsubstrates made of concrete (30 cm30 cm5 cm) were put on the riverbed at each station beforehand to determine metals and chlorophyll a contents, dry weight and ignition loss of the sediment (APHA, AWWA and WPCF, 1985; River Brueau and Japanese Ministry of Construction, 1997). Three replicates of the sediment in an area of 25 cm2 were scratched with a tooth brush from the surface of the artificial substrate and were taken into the plastic vessels with distilled water. The obtained data were scaled by ztransformation and then treated by principalcomponent analysis (PCA) in order to summarize the information on water and sediment quality in the River Akagawa.