As a non-market good, the value of irrigation water can be approximated by empirical investigations of farmers’ willingness to pay (WTP) for irrigation water. In this paper, a contingent valuation study on farmer WTP for irrigation water was conducted. With double-bounded bidding, an average WTP of 1021 RMB/ha/yr was found. The perceived value of water is falls short of the costs of irrigation water provisioning. This suggests that the use of irrigation water in Zhangye is not sustainable, and the price policy alone may not serve the purpose of efficient irrigation water management.