The National Assessment Impacts on Water Resources In addition to assessing the impacts of climate variability and change on a regional basis, the National Assessment will look at the consequences for major sectors of the U.S. economy, including water resources. The assessment of water resources includes the quantity of water available for withdrawal purposes from both surface- and ground-water systems; the chemical characteristics of those waters, especially as related to the health of humans and ecosystems; and the hazards posed by hydrologic extremes (floods and droughts) in terms of water quantity and quality. An adequate supply of clean water is an issue that is central to all social, economic, and environmental sectors. Many of the most significant concerns in the agricultural, forestry, ecosystem, energy, urban, commerce, and human health sectors derive from the basic issue of water availability and quality. Water resource planners and managers developing policies and management options use current information and projections on discharge, water quality, water use and demand, population, land use, environmental regulation (e.g. endangered species, water quality requirements), and technology development. CONSUMPTIVE WATER USE AS A PERCENTAGE OF RENEWABLE SUPPLY Information that is needed to forecast water availability includes improved estimation of regional population growth, land use change, and the likely water demand shifts that will accompany these demographic and economic changes. Forecasting water quality requires better projections of the influence of environmental regulations and management practices. For example, agricultural buffer zones would significantly improve estimates of water quality. Improved information on the likely range of climatic conditions would also be beneficial in ensuring that an adequate supply of clean water is maintained. An array of techniques is available for reducing climatic and non-climatic stresses on water availability and quality such as increasing reservoir capacity, changing the operating rules of water resources systems, improving long-range and short-range hydrologic forecasting, or increasing use of market mechanisms to change the allocation of water in light of changed conditions. Changing land use practices to reduce sediment and nutrient loss to surface water and ground water could significantly enhance water quality. U.S. Department of the Interior U.S. Geological Survey This page is <http://esp.cr.usgs.gov/info/assessment/water.html> Maintained by Randy Schumann Last modified Wednesday, 15-Mar-2006 14:38:42 MST