Water Quality in the Rio Grande Valley, Colorado, New Mexico, and Texas, 1992-95

Levings, G.W., Healy, D.F., Richey, S.F., and Carter, L.F., 1998, Water Quality in the Rio Grande Valley, Colorado, New Mexico, and Texas, 1992-95: U.S. Geological Survey Circular 1162; A discussion of water-quality issues, results, or findings in the Rio Grande Valley Study Unit (fig. 1) necessarily emphasizes the historical importance of surface water in this arid to semiarid environment. Surface water has been the "lifeblood of the Rio Grande Valley." Records from the sixteenth-century Spanish expeditions into the area report that irrigated agriculture was in use by some of the indigenous peoples. Where surface water and springs existed, people could exist. As European colonization of the area occurred, the introduction of new crops, such as wheat, barley, and oats, required the expansion of irrigation systems. As a result, settlements were established on the flood plains of the streams where agricultural land could be irrigated. Only when technological developments facilitated acc