River input pollutants
COD/mg/L 2010 2011 2012 2013 2014 2015 2016 2017 Average
Hokkaido 2 2.2 1.7 2 1.8 1.9 1.7 1.7 1.9
Aomori 2.2 2.2 1.8 2 2.2 1.7 1.8 2.2 2.0
Akita 1.7 1.6 1.8 2 2.1 1.9 2.1 2 1.9
Yamagata 2.4 2.3 2.8 2.7 2.5 2.8 2.5 2.4 2.6
Niigata 2.2 2.5 2.1 2.5 2.4 2.4 2.6 2.4 2.4
Toyama 2.3 2.4 2 2.2 2.1 2 2 2 2.1
Ishikawa 2.8 2.1 2.5 2.5 2.3 2.5 2.3 2.1 2.4
Fukui 1.3 1.6 1.6 1.4 1.5 1.7 1.9 1.7 1.6
Kyoto 2.5 2.6 2.4 2.7 2.2 2 2.1 2.5 2.4
Hyogo 1.7 1.7 1.8 1.8 1.8 1.8 1.7 1.7 1.8
Tottori 2 2.1 1.5 1.7 2.1 1.9 2.1 2 1.9
Shimane 1.9 1.7 1.9 1.6 1.4 1.6 1.7 1.8 1.7
Yamaguchi 1.9 2 1.6 1.8 1.7 1.9 1.8 1.9 1.8
Saga 2.4 2.4 2.1 2.2 2.3 2.1 2.4 2.9 2.4
Nagasaki 2 1.6 1.8 1.7 1.8 1.8 1.9 1.7 1.8
Average 2.09 2.07 1.96 2.05 2.01 2.00 2.04 2.07 　
TN(mg/L) 2013 2014 2015 2016 2017
Hokkaido 0.36 0.36 0.27 0.33 0.29
Niigata 0.18 0.14 0.14 0.15 0.15
Ishikawa 0.28 0.22 0.25 0.25 0.13
Fukui 0.18 0.18 0.18 0.18 0.12
Kyoto 0.35 0.25 0.24 0.28 0.18
Yamaguchi 0.1 0.13 0.14 0.12 0.13
Fukuoka 0.4 0.38 0.43 0.40 0.41
Saga 0.24 0.25 0.27 0.25 0.21
Nagasaki 0.33 0.31 0.27 0.30 0.23
TP(mg/L) 2013 2014 2015 2016 2017
Hokkaido 0.032 0.034 0.027 0.031 0.027
Niigata 0.023 0.02 0.02 0.021 0.016
Ishikawa 0.034 0.032 0.035 0.034 0.033
Fukui 0.016 0.016 0.017 0.016 0.013
Kyoto 0.024 0.02 0.021 0.022 0.015
Yamaguchi 0.014 0.012 0.014 0.013 0.012
Fukuoka 0.026 0.024 0.027 0.026 0.025
Saga 0.026 0.024 0.025 0.025 0.021
Nagasaki 0.022 0.026 0.02 0.023 0.026
BOD/mg/L Water Quality Class 2010 2011 2012 2013 2014 2015 2016 2017 Average
Ishikarigawa B 0.9 1.1 1.1 1.0 1 0.9 1.3 1.1 1.05
Shiribetsugawa A 1 0.7 0.7 0.6 0.7 0.9 0.7 0.7 0.75
Teshiogawa A 0.7 0.7 0.9 0.5 0.6 0.6 0.6 0.65 0.66
Iwakigawa B 1.5 1.8 1.6 1.2 1.6 1.9 1.9 1.5 1.63
Omonogawa A 1.5 1.2 1.6 1.9 1.1 1.0 0.8 0.9 1.25
Kyu Omonogawa C 0.7 1.0 0.7 0.5 0.5 0.5 0.7 0.5 0.64
Yoneshirogawa B 1.3 1.2 1.3 1.6 0.9 1.2 0.8 0.8 1.14
Mogamigawa A 1.6 1.8 1.6 1.4 1.5 1.8 1.7 1.0 1.55
Aganogawa A 1.1 1.4 1.5 1.3 0.8 0.9 0.8 0.7 1.06
Shinanogawa A 1.4 1.1 1.6 1.3 1.3 1.4 1.3 1.3 1.34
Jinzugawa B 1.4 0.9 1.1 0.8 1.1 1.3 1.2 0.8 1.08
Kuzuryugawa B 1.1 0.7 1.0 0.9 1.0 0.6 0.9 1.0 0.90
Yuragawa A 1.4 0.9 1.7 1.1 2.1 0.7 0.8 1.1 1.23
Hiikawa AA 0.9 0.9 1.2 1.1 0.8 0.9 1.0 1.1 0.99
Gounokawa A 0.8 0.6 0.6 0.7 0.7 0.7 0.5 0.6 0.65
Average 　 1.15 1.07 1.21 1.06 1.05 1.02 1.00 0.92 1.06