The U.S. Geological Survey is the Nation's largest earth-science agency and the principal Federal agency for providing hydrologic information and for appraising the Nation's water resources. The water resources of Arkansas consist of numerous streams, springs, lakes, and aquifer systems. Streamflow, ground-water levels, and water-quality data are collected throughout the state. These hydrologic data and other data are used in research and hydrologic studies to describe the quantity, quality, and location of Arkansas' water resources. The collection, analysis, and interpretation of these data are done in cooperation with other Federal, State and Local agencies, universities, and research centers.