Water supply reliability is a major concern for water users in regions subject to prolonged drought. In much of the western US, agricultural districts hold the most senior and reliable water rights. Access to this water during drought is of great interest to those with less reliable water portfolios. Temporary water transfers conditioned on drought conditions have been used in a number of locations worldwide to firm less reliable supplies. This presentation summarizes the most innovative features of these programs and proposes a structure for regional dry year fallowing programs in the western U.S. Specific concerns addressed include compensation for agricultural water users, third party impacts, equity issues among agricultural interests, effects of drought on water prices and cost effectiveness in achieving more reliable supplies. The presentation is based on research conducted over the last two years in collaboration with public agencies, water users and NGOs.