Arizona Agriculture and Water Use: Dependence on Colorado River

Welcome! This page allows you to explore Arizona agriculture, water use and dependence on the Colorado River. Be sure to explore the different Photo Albums as you look through the information, and visit some of the web sites linked in further sources. Each photo album is meant to enhance your understanding by looking a various maps and images of water resources, bondaries, and agricultural crops. This page is meant to give an understanding of where Arizona gets their water and how the majority of the water is used, bringing to attention some concerns with the strain on the resources.

Of the surface and ground water supplies across the United States, an estimated 40% of all the supplies go to agriculture. While Arizona is a geographical region that uses a higher percentage of their water for agriculture, nationally it is one of the largest uses of the countries water supplies. As populations continue to increase, and the climates change with global warming, water supplies are becoming more difficult to utilize, and coasts are increasing (CAST, p1). Arizona water use and resources is the focus of this page.

Arizona Water Resources and Use

Arizona’s primary surface water supply comes from the Colorado River. It was released in 2007 in the article The Layperson’s Guide To Arizona Water that Arizona was using “about 8 million acre-feet, or 2.3 trillion gallons, of water each year." More than 70% of Arizona water goes to agriculture. With the population continuing to increase, and less rainfall putting strain on the water reserves, draught is a real concern.

The majority of the water used for agriculture comes from the states fresh water withdrawls, accounting for roughly 5.4 MAF (measured in million acre feet), which is more than 70% of the states total water withdrawls. The withdrawl is split almost evenly between ground and surface water. While the Colorado River is the primary resource for Arizona fresh water, the Salt River, Verde River, and Gila River are also resources.

Colorado River

Upper and Lower Basin

The Colorado River is divided into two basins, the Upper Basin and the Lower Basin. It has been determined within the courts, in the process of creating managment of the use of the Colorado River System as a resource for several states, that the Lee Ferry is the dividing point between the two basins. All waters that naturally flow into the Colorado River above Lee Ferry are designated as being in the Upper Basin; and all waters naturally flowing into the Colorado River System below Lee Ferry are in the Lower Basin. The managment of the Colorado River as a resource is one of the more complicated in the country because it is a water reasource for seven states, and Mexico, making it a strained and hard working water resource. Colorado, Utah, Wyoming, and New Mexico are designated the Upper Basin States; while Arizona, California, and Nevada are the Lower Basin States. This seperation with Lee's Ferry as the dividing point was established prior to the 1922 negotiation among the seven states about the use of the river. Because of the wide use of the river, politics around rights to the Colorado River water have always run high, with California fighting for rights to the resource.

Agriculture in Arizona

Using data from the 2009 State Agriculture Overview, Arizona has over 26 million acres of land in farms, with over 15 thousand farms. In national rankings, the top three crops are: all lettuce ranked #2; vegetables, melons, potatoes, and sweet potatoes ranked #3; cotton and cotton seed ranked #9. These are the rankings within the US for these products. The rest of the farming categories come in around #23 and go up from there.

Cotton is a crop that requires a considerable amount of water and for that reason is the most concerning focus on Arizona water use. While lettuce still requires a significant amount of water at 9-12 inches per seasons when Arizona only gets a little more than 7in/yr, cotton fields require between 27.5 inches and 51 inches of water during an entire growth cycle. The highest water requirements are during the cottons flowering period, accounting for between 50% and 60% of the water requirements. With the realization that cotton requires such high amounts of water for successful crops, it is shocking that Arizona continues in this revenue of agriculture. With population growth predictions and the further strain it puts on the State water source, it will be interesting to see if cotton is a crop that will survive.

Links to Explore for Further Reading and Information

UofA Sharing Colorado River Water: A History ADWR Interactive Maps, Articles, more

Arizona Water Facts

The Colorado River Basin

Photo Credits

Colorado River:

Cotton Irrigation:

Gila River:

Goodyear Cotton Field:

Lee Ferry Divide Map:

Map of Arizona Rivers:

Salt River Canyon in Arizona:

Verde River (Arizona):


Hudson, John C. (2002). Across This Land: A Regional Geography of the United States and Canada. Baltimore: The Johns Hopkins University Press. Arizona Cooperative Extension,

CAST Issue Paper, Number 44, November 2009,

FAO Water,

Layperson's Guide to Arizona Water,'s_Guide_to_Arizona_Water.pdf

USDA NASS 2009 State Agriculture Overview,

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