A Unique Prehistoric Irrigation Project

Intentional diversion of water from its natural channels, for the purpose of irrigating regions of inadequate rainfall, is widespread in time and space. Usually, however, it is thought of as something of an innovation and as of more or less local significance." Inhabitants of humid areas are likely to under-estimate the very considerable portion of the earth's surface where the natural supply of moisture is insufficient to meet the needs of agriculture and other human economic requirements. In the United States alone virtually one-half the land area, westward from its longitudinal center, is arid or semi-arid, as are vast areas in Mexico and South America. Much of the Old World, particularly those countries adjacent to the Mediterranean and in the Near East, where ancient civilizations originated and flourished, are arid and desert-like. The valleys of the Tigris, the Euphrates and the Nile are classical examples of the dependence of life on the natural or induced overflow of these great river systems. The importance of water—and the tragedy of too much or too little—are reflected in the early literature, both sacred and profane, from the time of the Babylonian poet-philosophers downward through the centuries. An outstanding record of excessive rainfall is that of the Noachian flood; a minor example may be found today in the rain belt where someone, perhaps with a picnic in prospect, hopes that tomorrow may be fair! In between, the annals of virtually every people contain legends of floods and consequent devastation. Because of insufficient rainfall Moses, leading the Children of Israel back to the homeland, smites the rock, that they may drink; and the Arab sheik bespeaks the compassion of Allah in the matter of the failing desert spring. The crude methods of conserving water for domestic and agricultural use employed by present-day Pueblo Indians of the arid Southwestern United States are a matter of common knowledge. Natural springs and water holes are seasonal sources; rivers which carry water through the year serve those living adjacent thereto; but by far the greater number of inhabitants must conserve rainfall and storm water from the mountains and the high mesas in natural depressions, converted into reservoirs by means of dams and other artificial modifications. While in some instances ditches lead from these to nearby fields and gardens, the Indian women usually must carry water in jars for hand-irrigation of their meager crops. Archaeological investigation has shown that, with few exceptions, surprisingly similar methods were employed in prehistoric times in the same general area. This paper, however, is concerned with the historic aspects of irrigation only as a frame or background for an even more romantic phenomenon—prehistoric irrigation in the New World! Although a matter of record, it is not generally known that in South-central Arizona, long before the discovery of America, the native aborigines had perfected an impressive system of irrigation, which made possible the successful practice of agriculture over a period of several centuries. This system has been referred to as a "million-dollar project, constructed with nothing more than rude stone hoes and wooden digging sticks."