Impacts of Drought: Water Resources in the Colorado River Basin

Connie Woodhouse [connie.woodhouse@noaa.gov], National Climatic Data Center, NOAA, Boulder, Colorado.

            The recent drought in the western U.S. has been a wake-up call for many water management agencies, coming after two decades without drought that coincided with a rapid increase in population, especially in the Colorado River basin region. The 5-year average flow for 2000-2004 was the lowest on record in many parts of the Colorado River basin, calling into question the adequacy of the gage record for drought planning. It also motivated water managers to consider extended records of streamflow from proxy data as a tool for planning. Reconstructions of streamflow have allowed the recent drought to be placed in a centuries-long context, and water supply systems to be tested under a broader range of conditions than provided by the gage records. In addition, reconstructions of annual flow document low-frequency characteristics of flow over past centuries. Water managers responsible for large water systems are now interested in decadal scale variability and the predictability of flows at these times scales. This interest is related to some of the legal aspects of the allocation of the Colorado River and the implication future extended periods of drought will have for water management. The recent drought has brought the recognition of just how vulnerable the Colorado River basin water supplies and all related systems are to drought. There is a growing need for a better scientific understanding of long-term natural climate variability and its drivers, as well as the regional impacts of global climate change as they related to major water sources, such as the Colorado River.