Abstract
In this study, the authors proposed a supportive tool for consensus building on the introduction of advanced tertiary treatment systems in Shiga. The tool consists of the contingent valuation method (CVM) with which people's willingness to pay (WTP) for the comprehensive conservation of Lake Biwa, which can be conceived as a consensus of Shiga's people, is to be evaluated; the analytic hierarchy process (AHP) with which the weight for sewerage works within the entire measures and policies to protect the lake is to be determined by evaluation-sharing of ordinary people and officials in charge; and people's WTP for sewerage works which is to be calculated as the product of the former WTP and the weight. The proposed tool was tested with questinnaire surveys to people and officials, and its effectiveness was partly attested such as low coefficient-of-variation's among examinees in a workshop with a small group of people.
