Survey Prior to Starting the Project
The Estuary Natural Resource Survey of the three Kiso Rivers (the KST survey)
Over more than four years, from 1963 when the Nagaragawa Estuary Barrage was planned, an investigation team (headed by the late Prof. Kiyoaki Koizumi of Shinshu University) consisting of about 90 experts, was commissioned by the Ministry of Construction (now the Ministry of Land, Infrastructure and Transport) to investigate the environmental effects of the Nagaragawa Estuary Barrage, based on assumptions of the same levels of flood control and water use planning as those for the present barrage. The KST survey involved:
- The survey covered a wide range of items, including plants, benthos, plankton, water quality and sediment, as well as fishery products like ayu (a kind of sweetfish), and the corbicula, and an extensive area from the sea to 30 km upstream of the river mouth was surveyed.
- The survey team was made up of six expert groups on the ecology of ayu, the breeding and release of ayu, environment, biology, fishery, and physiological environment. The results of their investigations were discussed at group leaders' meetings and general meetings, and were included in a report.
- The survey was conducted with the full understanding of local fishing interests, and the contents of the survey report were made known to them and also to the general public through symposiums and seminars held over a period of time.