In a series of lectures delivered at the University of Michigan in the late 1980s, Wallace Stegner asked, “What do you do about aridity, if you are a nation inured to plenty and impatient of restrictions and led westward by pillars of fire and cloud? You may deny it for a while. Then you must either adapt to it or try to engineer it out of existence” (Stegner, 1987).
Debates regarding the West’s aridity and its implications for urban settlement, population growth, and irrigated agriculture are not new. In the 19th century, John Wesley Powell, Clarence King, and other scientists recognized the unique challenges posed by the region’s aridity as they conducted the initial geological surveys of the region. As head of the federal Irrigation Survey in the late 1880s, Powell unsuccessfully challenged Nevada Senator Bill Stewart and influential western ranching and landholding interests when he sought to constrain Western settlement so that land and water resources could first be surveyed and more closely assessed in terms of their carrying capacity. The arid West has also seen ardent advocates of growth and development, such as William Gilpin, first governor of the Colorado territory. Irrigation promoters sharing Gilpin’s perspective envisioned a boundless utopia in the western United States, and in fact wished to celebrate “The Blessing of Aridity” (Smythe, 1899). In the 20th century, many writers and historians, including Stegner, Walter Prescott Webb, and Bernard DeVoto reflected eloquently on the region’s aridity and on the ways in which settlement patterns were shaped by limited water resources.
For roughly 150 years, the West’s aridity has driven both practical development and scientific interest in the Colorado and the region’s other major rivers. The limits and values of these watercourses have resulted in many legal agreements and battles over control of
their flows; in this regard, the Colorado likely surpasses all other western rivers. With rapid increases in population and water demand in the Colorado River region in the past 25 years, issues of water management, science, and law have assumed tremendous importance and prominence.
The tree-ring-based Colorado River flow reconstructions issued in the late 1990s and early 2000s represent a key advance in scientific understanding of the region’s climate and hydrology. General findings from these reconstructions—that sustained, severe droughts have recurred for centuries across the region, that the 1890-1920 period was exceptionally wet, and that the long-term mean flow of the Colorado River is lower than the 15 million acre-feet per year reflected in the Lees Ferry gaged record (and less than the framers of the Colorado River Compact assumed)—are important in themselves. They are also important because their publication coincided with severe drought conditions in the late 1990s and early 2000s, and during a period of increasing population growth and water demands. The convergence of these findings and trends induced great concern among water managers in federal, state, regional, and municipal agencies across the Southwest. Recent water conservation and management initiatives, such as the Department of the Interior’s Water 2025 program, acknowledge the challenges and conflicts that will inevitably attend increasing water demands, limited (and likely decreasing) water supplies, and recurrent drought.
Urban water use has always been part of the context of the Law of the River and the operations of Lakes Powell and Mead, but for many decades it was overshadowed by large-scale irrigation development. The 1968 National Research Council report on water and choice in the Colorado River basin, for instance, noted that while population was growing rapidly in the region, “Much of the Colorado basin is almost uninhabited.” Large portions of the basin’s interior and arid regions remain sparsely populated today, but over the past 40 years, and especially since the mid-1980s, urban water demands within the basin and in water delivery areas outside of the basin have grown in importance in the context of Colorado River water storage and operational decisions. In earlier times, concerns regarding hydroclimatic variability and the Colorado River largely centered on the Bureau of Reclamation’s Annual Operating Plan and operational specifics derived from the Law of the River, such as equalization of storage levels between Lakes Powell and Mead. With today’s rapidly
growing urban water demands, allocations and obligations defined by the Law of the River are increasingly affected by municipal and industrial water needs. Not only are increasing urban water demands having noticeable effects on reservoir storage levels and instream flows, but the likelihood of further agriculture-urban water transfers promises to shift even more water away from streams and groundwater resources in rural areas.
A future of increasing population growth and urban water demands in a hydroclimatic setting of limited—and likely decreasing—water supplies presents a sobering prospect for elected officials and water managers. If the region’s water resources are to be managed sustainably and continue to provide a broad range of benefits to an increasing number of users, the realities of Colorado River water demand and supply will have to be addressed openly and candidly. If the region is to adjust successfully to its rapidly changing water supply-and-demand dynamics, elected and appointed officials, water managers, and the citizenry will require good information on urban water efficiency programs and on options and programs for adjusting to drought. There also needs to be a better appreciation of the economic, social, and environmental impacts that accompany agriculture-urban water transfers.
In the face of these realities and challenges, it is important to acknowledge that the Law of the River, the Colorado River water storage and conveyance infrastructure, and stakeholders tied to the region’s economy (including government agencies, farmers, urban water managers, and citizens) have all demonstrated a capacity to cope with water shortages. This report highlights the many factors that are likely to heighten future water management challenges, and which may eventually prompt substantial changes in policies for managing and using water. There is no technical cure-all or panacea capable of resolving the region’s increasing water supply-and-demand tensions. As this report notes, future events may necessitate a new level of federal and interstate collaboration on Colorado River water management. Such collaboration may also necessitate more extensive involvement of scientists and engineers with knowledge of water availability and demand trends in formulating water management decisions. The challenges of managing limited water supplies in a region with growing population and demands are not unique to the Colorado River basin, and Colorado River water managers are encouraged to
further explore potential benefits that might accrue from scientific exchanges with other regions of the nation and the world.
This report points to several important scientific findings as they relate to Colorado River hydrology and climate. It also includes findings related to cooperation among the basin states and between scientists and water managers. The report recommends that a comprehensive assessment of contemporary urban water management practices and other relevant water supply-and-demand issues be conducted, and that this assessment consider both the full implications of agriculture-to-urban water transfers and future development of regional water demand forecasting. In doing so, it defines an action-oriented study that could provide a more systematic blueprint for improving water management across the rapidly growing and arid Colorado River basin. As the Colorado River basin enters a new phase of coping with aridity and drought, future challenges promise to be more exacting than those faced in the past, and the cooperation that such a study would entail will be of great value. In the 21st century, good scientific information regarding Colorado River flows and variability, and close cooperation and communication at all levels, will prove more important than ever.