The U.S. Geological Survey (USGS), in cooperation with the Louisiana Department of Transportation, prepared hydrologically-conditioned geographic information systems (GIS) layers for use in the Louisiana StreamStats application. This data release contains vector and raster geospatial data used to delineate drainage basins and raster geospatial data for precipitation data used to characterize drainage basins. The 54 8-digit hydrologic units (HU8) represented in the Louisiana StreamStats study area are: 03180004, 03180005, 08030100, 08040202, 08040205, 08040206, 08040207, 08040301, 08040302, 08040303, 08040304, 08040305, 08040306, 08050001, 08050002, 08050003, 08060100, 08070100, 08070201, 08070202, 08070203, 08070204, 08070205, 08070300, 08080101, 08080102, 08080103, 08080201, 08080202, 08080203, 08080204, 08080205, 08080206, 08090100, 08090201, 08090202, 08090203, 08090301, 08090302, 11140201, 11140202, 11140203, 11140204, 11150205, 11140206, 11140207, 11140208, 11140209, 11140304, 11140306, 12010002, 12010004, 12010005, and 12040201.