ABSTRACT
I. Introduction: History of Colorado River Basin Development ............................................................... 250
II. Social and Economic Contexts .................................. 254 A. Water Quantity.................................................... 258 B. Water Quality ...................................................... 259
III. The Climatic Context................................................. 261 IV. Four Climate-Sensitive Decision Environments...... 264
A. International: The Border Region ...................... 264 B. Arizona and California: Interstate Issues in
the Lower Basin .................................................. 267 1. The Quantification Settlement
Agreement (QSA)........................................... 268 C. Native American Water Rights .......................... 269
D. Conjunctive Use and Management: Groundwater and Surface Water in Arizona..... 270
V. Opportunities for Technological Interventions and Climate Science Applications............................. 274 A. Opportunities for Application of Climatic
Information .......................................................... 275 VI. Present Conditions on the Colorado: Situation
“Normal” = Situation “Critical” ................................. 276 VII. Conclusion................................................................... 277 References............................................................................ 280
I. INTRODUCTION: HISTORY OF COLORADO RIVER BASIN DEVELOPMENT
The Colorado River flows 2300 km (about 1400 mi) from the high mountain regions of Colorado through seven basin states to the Sea of Cortez in Mexico (Figure 1). The river supplies much of the water needs of seven U.S. states, two Mexican states, and 34 Native American tribes. These represent a population of 25 million inhabitants, with a projection of 38 million by the year 2020. Approximately 2% of the basin is in Mexico. The Colorado does not discharge a large volume of water. Because of the scale of impoundments and withdrawals relative to its flow, the Colorado has been called the most legislated and managed river in the world. It has also been called the most “cussed” and “discussed” river in the United States. About 86% of the Colorado’s annual runoff originates within only 15% of the area, in the high mountains of Colorado and the Wind River Range in Wyoming. In the semiarid Southwest, even relatively small changes in precipitation can have
large impacts on water supplies. The coefficient of variation for the Colorado is about 33%.
