Abstract
Business integration of regional water supply authorities and departments, which are currently administrative unit each belonging to municipalities, is regarded as an effective solution for the sustainable water supply service in the circumstance of depopulation, increased investment in replacement, maintenance and repair of facilities, and insufficient technology transfer to the next generation. In this paper, we proposed methods to quantitatively predict the reduction of population served, water consumption, and replacement ad reconstruction costs with considering down-sizing of facilities, etc. By applying the methods to 73 water works authorities and departments in Ishikari River Basin (area: 15,000km2 , people: 3,100,000, 46 cities & towns), scenario analyses was conducted to estimate the revenues and expenses in the next coming 40 years. Without the integration of the regional water supply authorities and departments, large intra-regional differences in the costs to water supply were estimated. The costs at the year 2050 ranged from 200 up to 600 yen/m3. However, it was 249 yen/m3 in the case of the integration. Integration yielded the annual cost reduction of 1.7 billion yen, which was 3.3 % of the annual revenue expenditure.
