Rio Grande - River Modifications

River Modifications

The United States and Mexico share the water of the river under a series of agreements administered by the International Boundary and Water Commission,US-Mexico. The most notable of these treaties were signed in 1906 and 1944. The IBWC traces its institutional roots to 1889, when the International Boundary Committee was established to maintain the border. The IBWC today also allocates river waters between the two nations, and provides for flood control and water sanitation. Once viewed as a model of international cooperation, in recent decades the IBWC has been heavily criticized as an institutional anachronism, by-passed by modern social, environmental and political issues.

Use of that water belonging to the United States is regulated by the Rio Grande Compact, an interstate pact between Colorado, New Mexico, and Texas. The water of the Rio Grande is over-appropriated: that is, there are more users for the water than there is water in the river. Because of both drought and overuse, the section from El Paso downstream through Ojinaga was recently tagged "The Forgotten River" by those wishing to bring attention to the river's deteriorated condition.

There are a number of dams on the Rio Grande, including Cochiti Dam, Elephant Butte Dam, Caballo Dam, Amistad Dam, Falcon Dam, Anzalduas Dam, and Retamal Dam. In southern New Mexico and the upper portion of the Texas border segment, the river's discharge dwindles. Diversions, mainly for agricultural irrigation, have increased the natural decrease in flow such that by the time the river reaches Presidio, Texas, there is little or no water. Below Presidio the Rio Conchos restores the flow of water. Near Presidio the river's discharge is frequently zero. Its average discharge is 178 cubic feet per second (5 m3/s), down from 945 cubic feet per second (27 m3/s) at Elephant Butte Dam. Supplemented by other tributaries the Rio Grande's discharge increases to its maximum annual average of 3,504 cubic feet per second (99 m3/s) near Rio Grande City, Texas. Large diversions for irrigation below Rio Grande City reduce the river's average flow to 889 cubic feet per second (25 m3/s) at Brownsville and Matamoros.