The Rio Grande originates in the high mountains of southwestern Colorado, flows south through New Mexico, and then more or less southeast to the Gulf of Mexico. Between irrigation and damming in the upper portions of the river, flow between El Paso and the junction with the Rio Conchos from Mexico frequently is interrupted. Much of the agricultural wealth of New Mexico and the El Paso Region is entirely dependent on the flow of the Rio Grande, and much of the municipal water of El Paso comes from the river.
The river has been "tamed" in much of its pathway through New Mexico and the El Paso Region. Dams have alleviated the threat of floods from the spring runoff as mountain snows melt, and stretches of the river have been straightened to reduce evaporation of critical irrigation water. As a result, the current river valley is far different than when first encountered by the Spanish in the late 16th century.
The Rio Grande at the mouth of the Green River, southern Hudspeth County, Texas. This locality is well southeast of the Rio Grande agricultural lands of New Mexico and Trans-Pecos Texas, but still is affected by human influence. Water management to the north affects the quality and quantity of water, while introduction of exotic plants has greatly changed the riparian vegetation. Photo by Carl S. Lieb, 2 Apr 1993.