This paper summarizes economic and hydrological analyses of the impacts of the 1990 and 1996 U.S. Department of Agriculture (USDA) farm programs on irrigation water withdrawals from the Edwards Aquifer in south central Texas and on aquifer-dependent spring flows that support threatened and endangered species. Economic modeling, a regional producer behavioral survey, as well as institutional and farm characteristic analyses are used to examine likely irrigation water-use impacts. Hydrologic modeling is used to examine spring flow effects. Study results show that 1990 USDA commodity programs caused producers to require less irrigation water, in turn increasing rather than decreasing aquifer spring flows. Market economic factors are the dominant criteria influencing producer irrigation decisions. Farm-tenure arrangements and aquifer management responsibilities of the Edwards Aquifer Authority indicate that the 1996 Farm Act's PFC payment program will not cause an increase in irrigation withdrawals. Broader actions such as long-term water supply enhancement/conservation programs, dry-year water-use reduction incentives and water markets all provide tools for Edwards water-use conflict resolution. USDA farm programs do not apparently play a material part in the total debate. ¿ 1999 American Geophysical Union