Abstract
Introduction
In Japan, water pollution became a problem throughout the country during the high growth period, but water quality has been rapidly improved due to legislation and environmental awareness in society as a whole. However, the urbanization is progressing not only in Tokyo but also in rural areas, and there are still areas with severe water pollution in suburban areas. The former point-source pollution became widespread, and due to problems with wastewater treatment facilities in mountain villages, large river basins often have more contaminated areas upstream than downstream.
Focusing on nationwide observation records such as the results of the "water environment survey of public water bodies" that have been continued by the government since 1971, and the "national simultaneous survey of the familiar water environment" started in 2004 with the focus on civic groups Then, the long-term fluctuation of river water quality in Japan was examined.
Conclusion
In addition to the two types of nationwide long-term observation results, data collected before 1971 was collected and arranged to restore the past water quality. With regard to recent water quality, we have independently performed thousands of observations on a nationwide scale, and we have been able to clarify the current situation using data on general water quality, but none of them is sufficient yet. We will continue to collect similar data to improve accuracy.
