The Colorado and Rio Grande basins illustrate the range of coordination challenges and responses associated with drought adaptation in the western United States. First, state control over water allocation and federal roles in reservoir construction and management create coordination challenges related to sharing water among states during droughts and operating reservoirs. Second, interim rules and integrated data, modeling, and planning systems facilitate cooperation and learning among states, including the identification of positive sum or win-win options that boost system reliability. Third, the exclusion of groundwater, or of key stakeholders, can create a vicious cycle of legal uncertainty and conflict that weakens capacity to adapt and fuels costly conflicts. Finally, the national government plays an important facilitation role through funding resources, infrastructure, and monitoring networks to provide information and incentives for joint management. In both the Colorado and Rio Grande, the threat of federal action has been a powerful stimulus for cooperation or conflict resolution during droughts.