Recently as algae phenomenon has been intensified, the need for additional dam flushing has been raised. To establish the more rational policies concerning the dam flushing, it is necessary to evaluate the dam flushing. This paper attempts to examine households’ willingness to pay (WTP) for dam flushing by using a contingent valuation (CV). Especially, unlike other CV studies which used maximum likelihood estimation (MLE), this study employed Bayesian approach. This study surveyed a randomly selected sample of 1,000 households nation-widely, and asked respondents questions in person-to-person interviews about how they would be willing to pay for the additional dam flushing. Respondents overall accepted the contingent market and were willing to contribute a significant amount (1,909.4 won), on average, per household per year. The aggregate value amounts to approximately 35.7 billion won per year.