Hydrography lines. The dataset contains polygons representing planimetric hydrography, created as part of the DC Geographic Information System (DC GIS) for the D.C. Office of the Chief Technology Officer (OCTO). This is a complete new capture from aerial photography flown in mid to Late April, completed on April 24, 2015. This is part of a comprehensive sensor collection effort to sychronize orthophotos, oblique imagery, LiDAR, and basemap layers. The following planimetric layers were updated: - Barrier Lines- Building Polygons- Bridge and Tunnel Polygons- Curb Lines- Grate Points- Horizontal and Vertical Control Points- Hydrography Lines- Obscured Area Polygons- Railroad Lines- Road, Parking, and Driveway Polygons- Sidewalk and Stair Polygons- Swimming Pools- Water PolygonsDUE TO THE LOW ALTITUDE FLOWN TO CAPTURE THE COMPLETE IMAGERY FOR THE 2015 SENSOR FLIGHT, THERE IS INCOMPLETE AERIAL PHOTOGRAPHY COVERAGE AROUND THE WHITE HOUSE AND CAPITOL. FOR THESE AREAS, 2013 PLANIMETRIC FEATURES WERE SEEMLESSLY MERGED INTO THE 2015 DATA.