1994 Volume 38 Pages 277-282
In Koyama lake, phytoplankton blooms appear in summer season. This phenomenon might be influenced by the water quality. Therefore in this paper, in order to investigate the mechanism of phytoplankton bloom, the water qualities.in Koyama lake such as pH, Do, turbidity, nitrogen and phosphorous were observed from 1991 to 1993. And characteristics of these water qualities were also discussed.