Water Sources for Osaka City's Water Supply

The main source of the Yodo River is Lake Biwa, the largest lake in Japan. This is joined by three other rivers  Ethe Uji, Kizu, and Katsura rivers, each of which have their own distinguishing features  Eto form a river that has a comparatively stable flow volume as Japanese rivers go. As the source for the water supply for 14 million residents of Osaka City and the surrounding Kinki region, this river is what enables our urban lifestyle to continue.

The three water source areas in the upper reaches of the Yodo River each flow strongly at different times, fed by snowmelt in the Lake Biwa basin, rain during the rainy season in the Katsura River basin, and by rainfall during the typhoon season in the Kizu River basin. They complement each other, with the stable volume of water released by snow melt in the Lake Biwa basin making a particularly important contribution to the stability of the flow of the Yodo River. Because Lake Biwa, the largest lake in Japan, which occupies an area of approximately 674 km² and contains around 27.5 billion m³ of water, lies upstream from the Yodo River, it plays an important role in regulating the amount of water flowing down the river.