ABSTRACT
Global warming is already documented and certain to continue. It will reduce precipitation and increase temperatures over the globe, but already-arid areas like the American Southwest will bear the most significant consequences. The Lower Colorado River Basin’s population and industry depend almost solely on the assumption that 7.5 million acre-feet (maf) of water will flow through Glen Canyon Dam every year, but global warming will certainly reduce this amount in a relatively short time (50 to 100 years). Glen Canyon Dam has also had significant negative impacts on the biological and geological resources below it, and water is needed to restore these features. With cities, farms, animals and plants depending on ever-declining water from one river, tradeoffs will be made in the near future as global warming worsens. This paper first analyzes impacts of climate change on the dependents of the Colorado River below Glen Canyon Dam and then examines what recourse will be available in the future, given reduced runoff levels. Biological restoration below the dam is feasible, but methods will have to creatively use very little available water. Complete restoration is not possible, but saving a few well-selected species is a feasible goal. With reduced runoff inevitable, the only sustainable long-term options are policy change, agricultural reform and controlling growth in the Southwest.