Arizona Water Resource Newsletter
Water Resources Research Center
College of Agriculture and Life Sciences
The University of Arizona, Tucson AZ

More People, Less Water in the Offing

Sustainability and safe-yield, two terms used in reference to water supplies, connote a state of equilibrium, that water resources will not be consumed in excess of renewable supplies. Recent research suggests that meeting that water resource ideal may pose a very vigorous challenge. Arizona population is expected to greatly increase, and Colorado River flow will likely significantly diminish. In the tradition of the Old West a showdown threatens.

Report: Arizona’s Population to Double by 2036

With the U.S population reaching 300 million, population growth is much in the national news. A recent article brings the issue closer to home, at the state level, by projecting Arizona’s population growth into 2036. It is a report that will greatly interest water managers.

Phoenix the Citistate

According to the article Arizona will more than double its population during the next 30 years, with another 8.5 million residents added to the 6 million-plus that presently live here. Population increase will be especially pronounced in the major urban areas: Phoenix is expected to increase its present population of 4 million people to 9.7 million while Tucson, with a present population of just under 1 million, is expected to grow to 1.7 million.

An undoubtedly greatly enlarged Phoenix metropolitan area will account for two-thirds of the total population growth; metro Tucson is expected to account for 12 percent.

Checking Census Bureau population estimates the article notes that Arizona was the 17th-largest state in 2005. It progressed to 16th place by mid-2006 surpassing Tennessee. The coming year will likely see Arizona become the 13th largest state by outpacing Indiana, Washington and Massachusetts. Come 2036, Arizona will achieve top-10 status, in competition for the number 5 ranking.

The report breaks its forecasts into five-year increments, with Arizona’s population topping 7 million in 2010 and 8 million five years later. Another 2 million or more people will be added each subsequent decade.

The article also notes research done by the Maricopa Association of Governments that reports population densities will not be confined to the two major urban cores but will stretch from Sierra Vista to Kingman.

According to the article one result of this dramatic population increase is an expansion of current metro boundaries, with population spilling into surrounding counties. Land along I-10 will likely become prime real estate as the two urban centers literally grow closer together. The report refers to a study done by Robert E. Lang at Virginia Tech’s Metropolitan Institute stating that Pima, Pinal and Maricopa counties will make up one of the country’s ten “megapolitan areas.”

The increased population expanded over a greater area of the state means a greater need for regional planning. Taking center stage as the central city in a state that is part of a single global economic system, Phoenix will become “the Phoenix Citistate.”

In a statement water planners would appreciate the article says, “The challenge to plan for and accommodate the tremendous growth yet to come has never been greater.”

The article appeared in the October edition of Arizona’s Economy, a publication of the Economic and Business Research Center of the University of Arizona’s Eller College of Management. Marshall J. Vest is the author of the report and director of the center.

Drought May be Way of the Future
Analyses presented at a recent conference does not bode well for future Colorado River basin states’ water supplies. Marty Hoerling of the National Oceanic and Atmospheric Administration’s Climate Diagnostics Center presented the most dire scenario. He examined 18 different global circulation model outputs and noted that the Colorado River basin and other areas of the interior West will likely be greatly affected by increased temperatures due to global warming.

He calculated that flows at Lee Ferry could be reduced by 40 percent by 2060. In a shorter 25-year period, he suggested that Lees Ferry flows could decline below 12 million acre feet on average. This would be a serious situation considering that Colorado River water allocations among upper and lower basin states was figured in 1922 on an annual river flow at Lees Ferry of 16.4; each basin is to receive 7.5 maf each year. It is has been long realized that the 16.4 maf figure was flawed but Hoerling’s is a particularly low and unsettling revised calculation.

Almost all the models show a steady increase in temperatures; the models are less in agreement about the effect climate change will have on precipitation.

Other research presented at the conference concluded the expected increased temperatures will result in higher evapotranspiration and less snowpack; less runoff will then occur. Richard Palmer of the University of Washington reported that natural snow pack reservoirs are now diminishing and that the smallest snowpack on record occurred in winter of 2005

An Australian scientist offered what might be viewed as cold comfort to her U.S. colleagues; she said they should treat drought not as an anomaly but as the norm. She offered her country as an example where drought is not considered a disaster but a condition that might be expected as an aspect or characteristic of a very variable climate

Sponsored by the Geological Society of America, the Sept. 18 - 20 conference was titled “Managing Drought and Water Scarcity in Vulnerable Environments: Implementing a Roadmap for Change in the United States;” its intent was to develop a national drought strategy.

Plan Notes Ways to Increase Colorado River Supplies
The U.S. Bureau of Reclamation’s recently released 2007 Annual Operating Plan for Colorado River Reservoirs includes strategies intending to increase available water supplies. With increased river flows unlikely, the plan relies on better management of the river between Lake Mead and the Mexican border. A study once reported that the United States loses about 500,000 acre feet of river water each year to Mexico due to mismanagement.

One of the strategies is to build a small reservoir to ensure a more a more efficient delivery of water from Lake Mead to downriver farmers or irrigation districts. The way it now works is water released from Lake Mead for downriver agricultural use may take several days to reach its destination. Meanwhile changing conditions such as rain may result in the water not needed. Unclaimed by U.S. agricultural interests, the released water then flows to Mexico.

The 8,000 acre-foot reservoir, which would be located in California about 25 miles outside Yuma, along the All American Canal, would provide temporary storage until the water is returned to the system. Nevada will pay to construct the reservoir, which is scheduled for completion by 2009, to earn shares of the saved water.

The plan also calls for farm-farrowing, with farmers paid not to plant fields. The water not used would remain in Lake Mead and be available for other uses. Reclamation will contribute funds to farm-farrowing efforts. California has thus far made more use of this strategy than Arizona.

The plan’s most noteworthy strategy is to restart the Yuma desalter. Once viewed as a white elephant, a relic of a bygone era, the desalter now is viewed as a project worth revisiting during drought-struck times. The plan calls for restarting the plant for a 90-day test to determine feasibility of operation and costs. Scheduled to restart in March, the plant would operate at 10 percent capacity.

Operation of the plant was a very controversial issue at one time due to concern its operation would environmentally damage the Cienega de Santa Clara, a Mexican wetland, by cutting off agricultural runoff. In what is considered an extraordinary breakthrough various groups involved in the controversy were able to work out their differences to identify a set of management alternatives agreeable to all.

During the plant’s test run the water quality of the wetland will be monitored, with the Central Arizona Project funding the $80,000 water monitoring effort.

Robert Johnson, New Reclamation Chief
The U.S. Senate has confirmed Robert Johnson as the 20th person to lead the Bureau of Reclamation. He is well known by water officials in Arizona and throughout the West as Reclamation’s Lower Colorado Regional Director, the position he held before becoming Bureau head.

As regional director, Johnson oversaw the last 700 miles of the Colorado River, Hoover Dam, and numerous other Reclamation activities in southern Nevada, southern California and Arizona. In that capacity he initiated and directed significant changes in the management of the Colorado River.

Johnson joined Reclamation in 1975 in the Mid-Pacific Region in Sacramento. Since then he has held several other leadership positions, including Deputy Regional Director, Chief of Water, Land, and Power Operations Division in the Lower Colorado Region, and a management position in the Commissioner’s Office in Washington, D.C.

See Guest View, page 6, for statement from Commissioner Johnson.

New Law Joins Fight Against Exotic Plants
Congress recently passed a bill to strengthen the ongoing battle against nonnative plant species that have damaged river systems throughout the West. The Salt Cedar and Russian Olive Control Demonstration Act will support activities to control these nuisance plants that have challenged all efforts to eradicate them.

The new law directs the Bureau of Reclamation to work with the U.S. Department of Agriculture to conduct at least five salt cedar and Russian olive assessment and demonstration programs. The bill authorizes $20 million for FY2006 and $15 million annually from 2007-10 to provide grants to states and public/private partnerships to identify the best ways to eradicate these nonnative species.

The effort to eradicate thirsty nonnative species has gained momentum due to the ongoing drought; a mature salt cedar or Russian olive plant can consume up to 100 - 200 gallons of water a day.

Water supplies may have been the immediate concern but broader environmental purposes also are served. The exotic plants crowd out native trees like willows and cottonwoods, add salinity to the soil, and lower the water table. A dense growth of salt cedar can reroute a river’s flow, thus interfering with its ability to control floods and move sediment. Wildlife species are left without the natural backwaters they need.

Removing the plants without causing river bank erosion can improve stream flows and help restore native vegetation. Strategies to eradicate the salt cedar have included bulldozing, chemically treating salt-cedar infested land and releasing beetles that feed on the plant