Gulf of Mexico Watershed 0/^EXlCO^ Mississippi River Drainage Gulf Drainage, Non Mississippi Non Gulf Drainage ~ State Boundaries / Hydrologic Unit Regions Hydrologic Unit Subregions Streams Data Sources: USGS Hydrologic Unit Map Original Scale 1:250,000 USGS Gcip Data Digital Chart of the World Reach File 1 U.S. Navy ET0P05 5x5 Minute Balhymelric and Topographic Data Base Bathymetric contours 50 meter interval Index contours every 500 meters. 0 75 150 225 300 375 450 525 0 75 150 225 300 Environmental Protection Agency Region 6 GIS Water Quality Division Dallas, Tx 4 ------- |