The Water Resources Division of the U.S. Geological Survey, in cooperation with local, State, and other Federal agencies, obtains a large amount of data pertaining to the water resources of Arkansas each water year (October 1 through September 30). These data, accumulated during many water years, constitute a valuable data base for developing an improved understanding of the water resources of the State. To make these data readily available to interested parties outside the Geological Survey, these data are published annually in this report series entitled 'Water Resources Data-Arkansas" and are stored in the U.S. Geological Survey WATSTORE and U.S. Environmental Protection Agency STORET databases.