The U.S. Geological Survey's Groundwater Resources Program is conducting an assessment of groundwater availability to gain a clearer understanding of the status of the Nation's groundwater resources and the natural and human factors that can affect those resources. The goals of this national effort are to define the current status and improve understanding of the Nation's groundwater resources, to better estimate availability and suitability of those resources for use in the future, and to provide tools to estimate the future availability of ground-water for its various uses. Assessments will be completed for regional aquifer systems across the Nation to help characterize how much water we have, where groundwater resources are most stressed, how groundwater availability is changing, and where groundwater resources are most available for future use.