Bi-national water issues in the Rio Grande/Rı́o Bravo basin

Abstract

The Rio Grande (called the Rı́o Bravo in Mexico) is the fifth largest river on the North American continent. The river supports extensive irrigated agriculture as well as rapidly growing cities in three US and five Mexican states. From El Paso, Texas to the Gulf of Mexico, the river marks the international border between Mexico and the United States. Treaties for sharing the water of the Rio Grande between the two countries and arrangements for joint management were concluded in 1906 and 1944. Over time, a complex system of water management institutions has emerged. Water problems are pronounced, due to intensive development in an arid environment. Over the course of the last 40 years, the population in the border communities has doubled every 20 years. Demographic projections predict another doubling of the population by 2030. The entire Rio Grande basin is arid or semi-arid. Development has already led to a severe loss of biodiversity in parts of the basin. Development of new surface water resources is not a realistic option. The principal water management options are as follows: improved efficiency of water use, transfer of agricultural to urban uses of water, conservation and re-use of water, and treatment of brackish groundwater. Up to now, differences in law and levels of development between Mexico and the United States have made it difficult to develop basin-wide management strategies. In addition, regional differences in hydrological conditions argue in favor of developing separate but linked strategies for the sub-basins. This paper presents the key issues in two sub-basins with the largest population centers on the international border—the Paso del Norte (Las Cruces, New Mexico, El Paso, Texas and Ciudad Juárez, Chihuahua), and the Rio Grande Valley (Reynosa–Matamoros on the Mexican side, and MacAllen–Brownsville on the US side). Together, these cities will have 8 million inhabitants by 2030. The paper concludes with suggestions for improving management of river and groundwater in this bi-national growth region.