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SDSU Center For Inland Waters

Salton Basin-Colorado Delta

Shuttle view of the Salton Basin and Colorado Delta

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This website provides access to information on the natural resources, economy, and human population of the binational Salton Basin-Colorado River Delta region shown above. It also aims to facilitate information exchange and coordination among all groups interested in the region. We hope it will prove useful to students, researchers, decisionmakers and the general public.

First developed in 1996, the website reflects the experience and knowledge gained by SDSU scientists who have for twenty years taught a course on the ecology of the Colorado River delta region and for ten years been carrying out research in the Salton Sea region.

A Unitary Region

It may be helpful to point out the essential physiographic and hydrologic unity of this region. Structurally it occupies the Salton Trough, a small section of the dynamic junction or 'crack' between the North American and Pacific tectonic plates. The kilometer-deep soils and sediments of the Coachella, Imperial and Mexicali valleys and the lower delta region represent materials ground out of the Rocky Mountains, the Grand Canyon, and elsewhere by the Colorado River and its tributaries and delivered into the tectonic crack. These are the delta deposits of the Colorado River. Their areal extent is roughly 8600 km2, not including the underwater portion in the Sea of Cortez. The delta is not merely the few hundred square kilometers of plains along the lower river channel near the Sea of Cortez. A clear delineation of the whole delta is seen in the endpiece map in G. Sykes' classic monograph, The Colorado Delta (1937).

Hydrologically the region consists of two principal entities. One is the watershed of the Salton Sea, a terminal saline lake that receives inflows from an area that extends from Mt.San Gorgonio in the north to the Mexicali valley in the south. The other is the watershed comprised of the southern, exclusively Mexican part of the delta and adjacent uplands and mountains. What little surface water flows there are in this region travel mostly via old channels of the Colorado to the Sea of Cortez. A third but much smaller watershed is that containing the terminal saline lake Laguna Macuata (Laguna Salada) and bounded by the Sierra de los Cocopah and the Sierra de Juarez.

The distinctness of these three watersheds is partly illusory, of course. At various times in the past, and perhaps as recently as 500 years ago, the Colorado River flowed into the Salton Sea basin creating a large, deep freshwater lake there. This had an outflow to the Sea of Cortez. But even now Colorado River water - in the form of agricultural, municipal, and industrial wastewaters - is the main water supply for the Salton Sea. Also, during years of high flow in the Colorado it sometimes overflows into and fills the below sea level Laguna Macuata basin creating a lake 50-60 km long there.

Types of Information

The website will present four general types of information. First, it will serve as a network node that, via directories and hyperlinks, lists and facilitates access to websites of all institutions, agencies and organizations that provide useful information of any sort on the region.

Second, it will present annotated bibliographies of the scientific, technical, and general literature on the region, including the extensive 'gray' literature of government agencies, consulting firms, and other entitites.

Third, it will put on line the full text of certain documents relevant to the region that are of special interest and/or not easily accessed or available elsewhere. These will include unpublished reports, legislation, treaties, environmental impact reports (summaries only), engineering analyses (summaries), organizational position statements, political, legal, and editorial commentary, and so on.

Fourth, it will present various sorts of original information and databases developed by CIW scholars or compiled by them from other sources.

We welcome suggestions regarding information, documents or hyperlinks that you believe it would be useful to incorporate into this site, as well as correction of any errors present.

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