This activity will assess the extant body of scientific data and studies regarding Colorado River hydrology, including paleo-hydrological and dendrochronological studies. In addition to paleo-science, the study will also consider other hydro-climatic trends that might influence future hydrological variability across the river basin. The study's overarching objective will be to help produce an improved hydrological baseline to be used in support of water project operations and water resources management decisions (e.g., storage operations and diversions) across the Colorado River basin, and other regions of the western U.S., especially during periods of extended drought.These issues will be explored in multiple workshops, to be convened in the region, that will explore the scientific basis of Colorado River hydrology and the strengthening of institutional and related means for gathering and evaluating scientific information. The committee is also likely to convene a meeting, which would be closed to the public, to focus on finalizing its draft report. There are two components to the statement of task for this activity: science and technology, and science institutions and water management practices.1. SCIENCE AND TECHNOLOGY(a) "Extending" the Colorado River hydrologic record. Historical data, hydrological and climatic reconstruction methods, and models of Colorado River streamflow reconstruction and hydrology will be reviewed, with a goal of deriving recommendations to strengthen the basis of a synthetic Colorado River streamflow history that more fully reflects long- term conditions than the 100 years of recorded data.(b) Hydrologic data, models, and methods. To help advance hydrologic understanding and modeling capabilities in the Colorado River basin, the study will provide advice regarding future research needs and priorities in the realm of hydrologic data availability (i.e., adequacy of the existing streamgaging network) and analysis, hydrologic modeling, decision support systems, and related methods.2. SCIENCE INSTITUTIONS AND WATER MANAGEMENT PRACTICES(a) Institutional arrangements for establishing a process for gathering and evaluating hydro-climatic variability and water availability information across the Colorado River basin will be explored. The goal is to promote the development and use of a common scientific knowledge base by the basin's numerous water management authorities and entities.(b) Systems operations and water management practices. The hydrologic data being evaluated will be examined in the light of its implications for both near-term (e.g., 10 years) water project operations in the basin, and for longer-term water delivery obligations and other relevant dimensions of the Colorado River basin's Law of the River.The study is being conducted with support from internal resources from The National Academies. Additional sponsorship is being sought to procure resources that will be necessary to complete this activity.The approximate starting date of this activity was May 2005, and a single final report from this committee is expected to be issued in approximately July 2006.