Because water is not equitably distributed in time and place, in the right quantity with the adequate quality, water planning and management is used to redistribute the resource in such a way that tries to satisfy the necessities of water users, including the environment. Policies are proposed to improve the water management, however, selecting the best alternative can be difficult when tradeoffs among alternatives improve certain aspects of the planning and management and worsen others. This research establishes a methodology to evaluate water management policies in order to clearly and systematically identify policies that improve the water management. First, each water user, system or environmental requirement are evaluated using performance criteria. Second, performance criteria are summarized using the Sustainability Index. Finally, individual Sustainability Indices are grouped using the Sustainability by Group Index. The Sustainability by Group Index makes it possible to compare groups of water users and regions at a glance. This methodology has been successfully applied in the Rio Grande/Rio Bravo basin, a transboundary basin between the United States and Mexico. A set of scenarios was defined by water users, authorities and environmental organizations of the basin from both countries. A water resources planning model was constructed to represent the water management of the basin. The model was used to evaluate several scenarios and the benefits or damages that each policy provides. Two winning scenarios (called Meta-scenarios) that improve the management for water users, the environment and international treaty obligations were identified. Meta-scenario A is an immediate action scenario that includes: buyback of water rights, improvement in irrigation infrastructure, water demand reduction for irrigation districts in Mexico and the US, groundwater banking and the inclusion of environmental flows. Meta-scenario B is a short term scenario that includes the policies of Meta-scenario A plus expanded buyback of water rights, additional improvements in infrastructure and sharing of water savings between farmers in the US and Mexico. Results have been presented to decision makers and water users in both countries who will ultimately decide if they should implement the suggested policies. Most importantly, some alternative policies are now known that can help to improve the water management in the basin, for whom and where. / text