The Rio Grande marks the border between the United States and Mexico, which makes its management particularly complex. A century of engineering and binational governance has shaped the region; today there are multiple reservoirs, diversion channels, and irrigation canals. International and national river managers consider challenges from reservoir sedimentation, population growth, and land use change. Climate change, on the other hand, is barely addressed. Managers must plan for a Rio Grande that by mid-century will have lost 40–50 percent of current water levels. Urban population will have doubled. Irrigated agriculture and cities will continue to use the bulk of available water. The most promising response to meet human and ecological water needs with reduced dependable yield is conservation. To address water scarcity, IBWC/CILA should develop a sustainability plan that balances reduced dependable yield with human and ecological needs. Progress should be reviewed and necessary changes to water allocations be negotiated at 5-year intervals. Irrigation districts, municipal utilities, and environmental stakeholders should work with IBWC/CILA to develop drought management for their sub-basins.