Water resources data for the 2005 water year for Maryland, Delaware, and Washington, D.C. consist of records of water levels and water quality of ground-water wells. This report (Volume 2. Ground-Water Data) contains water levels at 352 observation wells, discharge records for 4 springs, and water quality at 118 wells. Locations of ground-water level wells are shown on figures 6 and 7. Locations of groundwater- quality sites are shown on figure 8. The data in this report represent that part of the National Water Data System collected by the U.S. Geological Survey and cooperating State, local, and Federal agencies in Maryland, Delaware, and Washington, D.C.