Abstract
This paper is intended as a report on the blue tide situation in Jyushiken River on the west side of Lake Shinji. In addition, we consider the factors leading to blue tide formation using a cross-sectional figure of water quality changes. The result shows that wind-driven current due to a strong west wind is one of the possible causes of blue tide. The other possible cause is not necessarily the high-salinity (8∼10‰) bottom layer of Lake Shinji, but rather, the relatively low-salinity water (5∼7‰) near the surface. The cause of anoxia of the relatively low-salinity water is long-term stagnation.
