Binational Dilemmas: the Contrasting Challenges for Environmental Management and Restoration of the Colorado River and Rio Grande

The United States and Mexico share waters of the Colorado River and Rio Grande. The two countries have signed joint declarations and begun talks focused on rehabilitating parts of these rivers affected by upstream dams and diversions. These areas include the Colorado River Delta and the Rio Grande downstream from Fort Quitman, TX. Other parts of these river systems are the focus on single country restoration efforts, such as the Glen Canyon Dam Adaptive Management Program and the effort to recover the Rio Grande silvery minnow. Regional and international coordination and collaboration are needed to focus limited restoration funds toward their most beneficial use. Analysis of historical records, published studies of channel change, and computation of sediment mass balance conditions demonstrates that the challenges and difficulties of rehabilitating different parts of the Colorado River and Rio Grande vary greatly. There is little accordance between the importance and tractability of restoration opportunities and the magnitude and location of investment in these opportunities. In some cases, large river management problems are focused on relatively intractable problems, while elsewhere relatively modest and solvable problems are ignored. We demonstrate how watershed scale analysis of the magnitude of hydrologic and geomorphic perturbations and the costs of addressing these perturbations can help guide the allocation of limited public resources to best meet the challenges faced by Mexico and the United States in rehabilitating its shared rivers.