The Colorado River Paul Glenn Overview. Water is the most abundant resource on Earth, covering over 70% of its surface. But much of the human population lives in areas that do not naturally have enough water to support its existence. In the American West alone, trillions of dollars have been spent diverting natural sources of water to farms and cities. It is one of the most contentious political issues of the last 100 years. And the very acts of diversion represent some of mankind’s greatest engineering achievements. Water is organized constantly to enable the interactions that support human life. What is being organized? The resource being organized is the water of the Colorado River. The Colorado River runs 1,450 miles from La Poudre Pass in the Rocky Mountains of Colorado to the Gulf of California in Mexico. In terms of both its length and total flow, the Colorado is a relatively small river; it is dwarfed by the Mississippi. However, the river is the only major water system in the Southwest United States, magnifying its importance. The river is fed annually by snowmelt from the Rocky Mountains. In addition to runoff directly into the river, significant tributaries, including the Fraser River, Blue River, Gunnison River, Gila River, Escalante River and Dirty Devil River feed it. The organizing system consists of dams, aqueducts and irrigation canals. Dams capture the flow of the river, storing it in reservoirs. Aqueducts transport water away from the river for use elsewhere, either by pumping it uphill or by directing it downhill. Irrigation canals are similar to aqueducts in that they move water out of the river, but are typically shorter and less engineered. Why is it being organized? Water supports many interactions, including the generation of electricity, the irrigation of land for farming, human uses such as drinking, bathing making waste and recreation, and natural uses like supporting plant and animal habitats. Water in the West has generally been organized to support the growing populations of Western cities without direct access to natural water sources (especially Los Angeles, and, to a lesser extent, Phoenix) and to irrigate the crops necessary to feed these populations and provide a livelihood for Western farmers. How much is it organized? Water is a generic resource, and no specific drop can be uniquely identified. Its use is measured in acre/feet, a unit that represents the amount of water that would cover an acre of land to the depth of one foot (approximately 325,000 gallons; the average U.S. household uses half an acre/foot of water annually). The Bureau of Reclamation of the Department of the Interior (USBR) is responsible for managing the water resources in the Western United States, and carefully tracks water entering and leaving the organizing system by both natural and man-made forces. It provides annual reports detailing the diversions, returns and net usage of all parties holding rights to make beneficial use of the water resources, and tracks the amount of water entering and leaving the organizing system by natural forces (snowmelt, runoff, evaporation, etc.). How or by whom is it being organized? A variety of structures organize the resources and make them available to users. The primary structure organizing water are dams, aqueducts and irrigation canals. USBR holds the primary authority over all three, in addition to other federal, state and local government agencies and private companies. There are 34 dams on the Colorado River. They organize water by blocking its natural flow and creating reservoirs, which store water resources for later use. There are tradeoffs involved with organizing water into a reservoir, chiefly increased evaporation. In total, dams create 65 million acre/feet of reservoir capacity on the river. Dams also support an interaction of the organizing system: creating electricity. The dams of the Colorado River combine to generate 10 million megawatt/hours of electricity annually, of which seven million megawatt/hours are generated at the Hoover and Glen Canyon dams. Aqueducts and irrigation canals are the two other structures that allow for interactions with resources in the organizing system by transporting the resource to the location where the interaction will take place. The two most significant are the Colorado River Aqueduct, which is operated by the Los Angeles Municipal Water District, and diverts 1.2 million acre/feet per year 242-miles from Lake Havasu to Los Angeles, and the Central Arizona Project, which diverts 1.5 million acre/feet per year 336 miles from Lake Havasu into central and southern Arizona. When is it being organized? The structures organizing water resources in the Colorado River operate constantly, but the organization is considered in annual cycles. This is because of the natural annual cycle of snowmelt that adds resources to the system. Water is constantly entering and leaving the organizing system through diversions and returns. By one estimate, a single drop of water can support 17 different interactions over the course of the year1. Other Considerations. A key consideration of the organizing system of the water of the Colorado River is who has the right to make use of its resources. Dams, aqueducts and irrigation canals make interactions possible, and the USBR accounts for these interactions, but a separate system of laws, treaties and court decisions, known collectively as the Law of the River, define to whom these interactions are available. At the core of the Law of the River is the Colorado River Compact, a 1922 agreement among the state governments of Colorado, Utah, Wyoming, New Mexico, California, Nevada and Arizona (although Arizona did not ratify the agreement until the 1960s), which apportions part of the annual flow of the river to users in each state. 1 Reisner, Marc (1993). Cadillac Desert. Penguin. p. 120. Water rights are governed in the West based on the principle of prior appropriation: once someone has diverted and made beneficial use of water, they are entitled to that same amount each year in perpetuity, so long as they continue to make beneficial use of the water. The Colorado River Compact arose in part, in response to fears that left unchecked, Los Angeles would continue to divert water from the river before the other states could make beneficial use of it2. The history of this organizing system is full of similar political battles over what interactions should be available with the resources (such as the controversy over whether to build the Bridge Canyon Dam near Grand Canyon; the dam was not built due to a general public outcry spurred by the Sierra Club3) and who should be able to take part in those interactions (such as the 1944 United States-Mexico Treaty for Utilization of Water, which guarantees delivery of 1.5 million acre/feet to Mexico annually). 2 Reisner, 1993, p. 124 3 “American Nile.” Cadillac Desert. 1996. KTEH-TV/PBS. Accessed Electronically. Artifact: Who Benefits from the Organizing System? A key consideration in the analysis of the organizing system of the Colorado River is who benefits from its existence? Where are the users of the organizing system located, and how do they interact with its resources? The Bureau of Reclamation publishes detailed accounts of diversions from the river, including forecasts. I examined its report on forecasted use for 2015 in the Lower Basin1 (California, Southern Nevada and Arizona) to find additional insight into this question. The data is presented as a PDF, and needed a significant amount of cleaning to extract the values to a usable format. I then used Google Maps to locate a latitude and longitude for each listed water user, and assigned each to a category. As is always the case, creating the categories posed a significant challenge, for several reasons: it was difficult to find information on some of the water users, it was difficult to discern the exact nature of how the water was being used, and it was difficult to determine the appropriate level of granularity. For example, the Central Arizona Project diverts water from the Colorado River to the Phoenix area and it is used along the way for irrigation. I classified it as Metropolitan because that is, presumably, what the majority of the diversion is used for. Another example is the University of Arizona and Yuma Union High School District. I classified both of these as Government, although an additional category of Education would have better described them. The below maps are provided separately as high-resolution images, and an interactive map is available here which allows the user to explore the data in depth. Full Lower Basin View 1 http://www.usbr.gov/lc/region/g4000/hourly/forecast15.pdf Southern California Detail Las Vegas Detail Yuma, Ariz., Detail Summary of Use by State and Purpose .