Newspapers and other sources, I learned that the water quality of the Tsurumi River is the worst river among the first-class rivers in Japan. What is Yokohama City doing to clean the Tsurumi River?

Regarding the improvement of the water quality of urban rivers, we believe that the spread of sewers is indispensable. In cities in the Tsurumi River basin, not only Yokohama City but also Kawasaki City and Machida City are working to spread sewerage.As of the end of FY2008, the sewerage penetration rate in each city was 99.8% of Motoichi, 99.3% in Kawasaki City, and Machida City. 92.9% of Machida City, significantly higher than the national average of 72.7%.

In addition, in addition to the three water reclamation centers in Tsuzuki, Kohoku, and No. 1 in Motoichi, there are seven water reclamation centers in operation, two locations in Kawasaki City and Machida. We are working to improve water quality.

In addition, at the Tsurumi River, measurements are performed at 10 locations based on the Kanagawa Prefecture Public Water Quality Measurement Plan, but in 2008, nine of them achieved environmental standards, indicating the degree of water contamination due to organic matter The average annual BOD value of BOD is 2.8 mg per liter, which has been greatly improved by about half compared to 10 years ago.

In this way, water quality has tended to improve over time due to the spread of sewers, and the Shimo-Water Works Bureau's biota survey on fish in the Tsurumi River conducted by Shimokawa showed 18 species in 1987, 24 species in 1989, and 12 species of fish, including fish that are said to live in clean waters, such as sweetfish and Ugui. We believe that these results have emerged as an effect of various initiatives for the water environment conservation, including the spread of sewerage systems.

Yokohama City will continue to work with cities in the Tsurumi River basin, including the promotion of advanced sewage treatment, to further improve water quality.