I studied the effluents of three copper sulphide mines, Tateri Mine and Kawamata Mine in Nara Prefecture and of the Imori Mine in Wakayama Prefecture, with regard to their effect on stream organisms. The water insects were collected quantitatively at several stations of the rivers which receive the mine-water(Figs. 6,7,8,9). The effect of the effuents is very distinct. The water insects decrease in species number as well as in individual number with the distance from the source.
