Estimating the demand curve for farm irrigation water is a matter of serious concern in most of the Western States today and may be so in portions of the humid East in the near future. Farmers and other users have filed claims to all readily available streamflow, and private and public agencies have exhausted nearly all low-cost storage sites. Additional water can be made available only at much higher costs. If these higher costs are to be repaid, facilities must be designed to be utilized to their full capacity. Such designs must take into account the slope and position of the demand curve for irrigation water. The results presented here should be useful to project planners undertaking to determine the feasibility of proposed water projects. These results will also provide guides for allocating water supplies in multiple-use projects among various users, and they will help water agency managers to assess how proposed price schedules will affect income accounts for their farmer patrons. The authors wish to thank B. C. French, G. W. Dean, J. N. • oles, H. 0. Carter, and G. A. King for their comments and suggestions. This project was supported by the Water Resources Center, University of California.