87th AMS Annual Meeting

Thursday, 18 January 2007: 11:00 AM
Critical challenges in incorporating climate into management of the Colorado River
214C (Henry B. Gonzalez Convention Center)
Andrea J. Ray, NOAA/CIRES/CDC, Boulder, CO; and D. Kenney
The recent multi-year drought in the Colorado River basin has resulted in deficits in Lakes Powell and Mead. As of August 2006, current storage in Lake Powell, the massive 27 million acre-feet (MAF) impoundment formed by Glen Canyon Dam is 12.3 million acre-feet or about 50 percent of live storage. Projected unregulated inflow to Lake Powell for water year 2006 is 8.78 maf, or 73 percent of average. Typically, the storage capacity on the river provides ample protection against drought shortages, but declining reservoir levels are raising the prospect that the states of the Upper Basin (Colorado, Wyoming, Utah and New Mexico) may soon be required to cease water diversions that are junior to the 1922 Colorado Compact in order to meet obligations to downstream users. A 1995 study, the Colorado Severe Sustained Drought Study (SSD, ), looked at the impact of a 35-year drought. However, recent conditions show that even a 5-7 year drought can have a significant impact on the system, and reveals critical challenges in policy implementation in the Colorado Basin.

In a study revisiting and updating the general assumptions, themes and findings of the SSD study, we find that three changes to the system over the last decade have change the system's vulnerability to climate: (1) the sociopolitical, legal and demographic context of the region has evolved rapidly, especially in the Lower Basin; (2) new water projects and management regimes have been implemented; and (3) there is currently a much more advanced understanding of the climate system-past, present, and future-including the potential impacts of climate change and shorter drought periods on water management that were not included in the original investigation. The overarching issue to be addressed in the proposed work is to understand how the changing context of the region has introduced criticality for water management with respect to shortages due to increasing demand and shortages related to climate variability and change.

In addition to implementation of current policies, the drought suggests that planning and policy development in the basin must consider potential future climate scenarios, including multi-year droughts and the effects of increased temperatures. Two examples are the developing “shortage sharing agreement,” and the Environmental Impact Statement for the Aspinall Unit on the Gunnison River. This presentation will discuss the 2006-2007 policy landscape with respect to the Colorado River. We will also discuss needs for climate products that can aid the increasingly difficult and urgent water resource decision-making processes in the Colorado basin.

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