Water quality in the nation's rivers and lakes improved slightly in 2000 compared with a year earlier, with almost 80 percent of sites meeting environmental standards, the Environment Ministry announced Tuesday.
The annual study showed that 79.4 percent of some 3,274 bodies of water sampled met government-mandated water standards, logging the highest percentage yet, up from 78.7 percent for some 2,599 sites in the previous year.
The cleanest rivers were the Rekifune River, the lower Kitamihorobetsu River and the Hiroo River in Hokkaido, while those with the worst quality were the Benten River in Kagawa Prefecture, Kokubu River in Chiba Prefecture and Furo River in Saitama Prefecture.
The cleanest lakes were Lake Shikotsu and Lake Shikaribetsu in Hokkaido and the Ikehara Reservoir in Nara Prefecture. Chiba Prefecture's Teganuma retained the title as the nation's lake or reservoir with the worst water quality for the 27th straight year. Sanaruko Lake in Shizuoka Prefecture finished second and Inbanuma, in Chiba Prefecture, came in third worst.