Measures for the conservation of water quality in Lake Biwa and the Akanoi Bay initiative

Abstract

AbstractLake Biwa is the largest lake in Japan, supplying water resources to support the lives and economic activities of 14 million people living in its downstream area. It also is one of the oldest lakes in the world, being more than 4 million years old, and ‘an ecological treasure house’ inhabited by a variety of animals and plants. In the Shiga Prefecture, to pass Lake Biwa to the next generation in a sound condition, the ‘Lake Biwa Comprehensive Conservation Plan’ (Mother Lake 21 Plan) was developed. It has been striving to achieve the comprehensive conservation of Lake Biwa, with the support of national ministries and also with the support of the people of the prefecture. This plan comprises three major areas: ‘Maintaining Water Quality’, ‘Improving the Recharge Capacity of the Soil,’ and ‘Preserving the Natural Environment and Scenic Landscapes’. The goals of the generated stages of each plan were agreed by all relevant parties. ‘The Lake Biwa Water Conservation Plans’ were settled upon in regard to preserving water quality. The Mother Lake 21 Plan represented a long‐term vision, including the development of water conservation measures. In the current 5th period plan, ‘the Akanoi Bay watershed run‐off plan Akanoi measures’ were added, as a supplement to the traditional approach, to strengthen measures for the non‐point source pollution. Akanoi Bay is a narrow, closed bay, being located in an area of the lake in which the water has been badly polluted because of the spread of the urban areas surrounding the lake, and because of the rapid influx of people. It also is the area where the people are very active in the environmental protection and is the model case study illustrating where the government and the inhabitants can work together to promote measures for addressing non‐point source pollution.