We decided Miomotegawa river was the object of our investigation since it is one of the most important salmon rivers in Japan. A great number of salmonshave returned to the river, and it was expected to contain relatively lower cation concentrations since granite is widely distributed in the river catchment area. The concentration of calcium and magnesium were less than a half of that of other major rivers. The concentration of analyzed parameters indicating water quality effect on salmons, $NO_{3},\;SO_{4}\;and\;NH_{4}$, were 1.37, 4.08 and 0.01mg/l, respectively. Most parameters down stream were greater in concentration than in the upper stream.