The American Nile Running Dry: An Overview of the Colorado River and Water Shortage

Photo courtesy of www.smscs.com

The Colorado River, nicknamed the American Nile, is arguably the most precious asset to the southwestern United States. Supplying water to nearly 36 million people both inside and outside of the basin, irrigating 3.5 million acres of farmland, generating 4,000 megawatts of hydroelectric capacity, and entertaining over 20 million recreationalists and visitors annually, the Colorado River is a lifeline to the Southwest. Today, due to over use of the river, the Southwest faces a water shortage problem in the Colorado River Basin.

Colorado River Facts

Overview of the Colorado River Basin
Photo courtesy of http://obrag.org

Starting in the southern Rocky Mountains of Colorado, the Colorado River extends 1,450 miles across seven U.S. states and two Mexican states where it forms the Colorado River delta and empties into the Gulf of California. Over its journey, the river enters varying climates. Beginning in the mountains of Colorado, through semi-arid regions in Utah, and eventually making it’s way though arid regions of the Sonoran and Mojave Deserts. The majority of the basin is characterized by an arid climate, receiving on average 6.5 inches of rain annually. (This number is the average across the basin with some areas in the Rocky Mountains receiving an average of 40 inches of rain annually to areas in the desert receiving an average of 0.4 inches of rain annually)

The river and its tributaries - the Green, the Gunnison, the San Juan, the Virgin, the Little Colorado, and the Gila Rivers - are referred to as the "Colorado River Basin." The Colorado River Basin drains 242,000 square miles in the United States, or one-twelfth of the country's continental land area, and 2,000 square miles in Mexico, making it the seventh largest watershed in North America. 

Division of Upper and Lower Basins in
the Colorado River
Photo courtesy of www.cejournal.net

The Colorado River Compact of 1922 divided the Colorado River Basin into the Upper Basin and the Lower Basin. The Upper Basin includes the U.S. states of Arizona, Colorado, New Mexico, Utah, and Wyoming from which waters naturally drain into the Colorado River and the Lower Basin includes the U.S. states of Arizona, California, Nevada, New Mexico, and Utah, again from which waters naturally drain into the Colorado River. The division of the Upper and Lower Basins is at Lees Ferry in northern Arizona. 

About eighty-five to ninety percent of the water that flows through the Colorado River originates above Lees Ferry from snowmelt in the Rocky Mountains.

Colorado River Compact of 1922

Example of the Colorado Doctrine
Photo courtesy of coyotegulch.files.com

Conflict over water in the West is not a recent topic. From before the time of Colorado statehood in 1876, the legal right to divert and use water has been deliberated. In 1872, the appropriation doctrine or the Colorado Doctrine was established, laying the foundation of water rights in the West. The Colorado Doctrine states that, “water rights are unconnected to land ownership, and can be sold or mortgaged like other property. The first person to use a quantity of water from a water source for a reasonable and beneficial use has the right to continue to use that quantity of water for that purpose. Subsequent users can use the remaining water for their own beneficial purposes provided that they do not impinge on the rights of previous users”. A reasonable and beneficial use, as defined by the Colorado Doctrine includes “municipal and industrial uses, irrigation, hydroelectric generation, and livestock watering. More recently, the concept has been broadened to include recreational use, fish and wildlife protection, and enhancement and aesthetic enjoyment”. This is what differentiates senior water rights (first users) versus junior water rights (subsequent users). 

Division of the entire Colorado River to each state.
US Department of the Interior Reclamation Bureau,
1971-2005 [USDIRB]

Since each state administers water rights individually and not all of the Colorado River basin states use a pure form of the Colorado Doctrine, the Colorado River Compact of 1922 was established. The compact was created in order to ensure that each individual state would cooperate in managing the river not overuse the water. 

The Colorado River Compact of 1922 divided the basin into the Upper and Lower Basins and allotted 7.5 million acre-feet of water to each basin in perpetuity, or indefinitely. To put into proportion how much 7.5 million acre-feet is, one acre-foot can provide enough water for 2 average households of 4 people for one year.

Hoover Dam from above.
Photo courtesy of photographer Lisa Taylor

The Colorado River Compact did not apportion a specific amount of water to each state within the basins. In 1948, through what is known as the Upper Colorado River Basin Compact, the Upper Basin agreed upon annually allotting Arizona 50,000 acre-feet of water and the remaining amount of water by percentages. The Lower Basin agreed in 1962, by means of the Supreme Court, to divide the 7.5 million acre-feet in a similar way, by percentages. Above is a chart that shows the overall breakdown of the Colorado River. In 1944, the U.S. entered into a treaty with Mexico allotting 1.5 million acre-feet to pass into Mexican territory. 

In order to satisfy the Colorado River Compact, infrastructure such as Hoover Dam and Glen Canyon Dam have been built to store water along the river for future use. In total, all of the reservoirs along the Colorado River can store 60 million acre-feet of water, which is approximately four times the annual flow of the river. 

What is the Problem?

The Colorado River is currently listed as the number one most threatened river on the endangered rivers list. This is because management on the river is far outdated and demand of the river’s water far exceeds its supply. This can be traced back to the Colorado River Compact. The allotments of water entitled to the Upper and Lower Basins was agreed upon based on the rainfall patterns and flow of the river observed in the years prior to the treaty’s signing. However, the only data available on the basin’s annual precipitation and river’s annual flow was from 1910 to 1922. This twelve year period, as shown in the paleo reconstruction of the Colorado River flow, has an unusually high flow average never seen before, so the basis of the Colorado River Compact allotments set the stage for water shortage in the Colorado River Basin. 

Paleo Reconstruction of Colorado River flows.
Graph courtesy of Woodhouse et al., WRR, 2007

The average flow for the Colorado River is around 13 million acre-feet, whereas the Colorado River Compact agreed upon allocations based off of an 18 million acre-feet average flow. Although the average annual flow is around 13 million acre-feet, the flow on the river is highly varied with a range of 6 to 20 million acre-feet of water produced each year. Each of the seven states, and Mexico rely heavily on water from the Colorado River and as of 2013, the Colorado River supplies water to nearly 36 million people. This number increases each year as the Southwest is the fastest growing region in the U.S., so each year the river’s supply dwindles to the point that the Colorado River is drying up before it reaches the Gulf of California. 

Dried up Colorado River Delta. Since 1998,
the river has not reached the Gulf of California.
Photo courtesy of photographer Pete McBride.

The next problem aiding to water shortage in the Colorado River is due to climate change. It is estimated that climate change will reduce the flow in the Colorado River by 10 to 30 percent by 2050. This loss of flow 

U.S. drought monitor shows that the Southwest is in a
severe to extreme drought with some areas in a exceptional drought.
Chart courtesy of http://droughtmonitor.unl.edu

is due to rising temperatures reducing the amount of  

snowfall in the Colorado Rocky Mountains, causing a decrease in runoff to the headwaters of the Colorado River. A reduction in the Colorado River flow will likely cause further drought conditions throughout the Southwest, similar to the droughts seen from 2000 to 2013. In this recent thirteen year period, the Colorado River Basin only produced three years where the runoff reached average or 

above average values.  

Many of the reservoirs along the river have reached record lows in the amount of water stored. Lake Powell, for instance held only one-third of its storage capacity in 2005, the lowest storage ever recorded since 1969. In 2010, Lake Mead was eight feet away from reaching the first “drought-trigger,” which would cause Arizona and Nevada to ration water use as defined in the Colorado River Compact. 

The red and white makings on the canyon walls, known as bathtub rings, show how much water was once stored in Lake Powell. Today, these rings are nearly 100 feet high, as the Southwest faces its second consecutive period of drought.
Photo courtesy of http://picturesandplanetickets.files.wordpress.com

Water shortage in the Colorado River Basin is inevitable due to over use of the water, the arid region in which the basin sits, and ever growing southwestern urban centers. The future of the river is uncertain, however if agreements aren’t met to reduce the use of Colorado River water, the Southwest might just shrivel up its lifeline, a catastrophic event that will have many physical, economical, and environmental consequences. 

Below is a short film titled, Colorado River – America’s Most Endangered River 2012 produced by Pete McBride through AmericanRivers.