Sharing water between jurisdictions is difficult in the best of times. Water is often a symbol of sovereignty, and nations and subnational jurisdictions that share transboundary water resources will engage in heated disputes even when there is a predictable and plentiful water supply. But climate change increases variability in river basins around the world. This variability means increased risk of drought and related water shortages. How can jurisdictions – whether international or subnational – equitably and sustainably share in water shortages in the rivers, lakes, and aquifers they share? The legal history of the Colorado River in North American offers lessons based on successes and cautionary tales based on failures for other efforts to share in water shortages in transboundary river basins. The Colorado River is shared between two countries, seven states, and dozens of Native American tribes in an arid region regularly confronting drought. Decades of legal disputes, governance innovations, and complex negotiations have made the Colorado River a fascinating and complex case study to explore how jurisdictions can share in water shortage.