Water-quality data are provided for six sites in Navajo National Monument in northeastern Arizona. These data describe the current water quality and provide baseline water-quality information for monitoring future trends. Water samples were collected from six sites near three ancient Indian ruins during September 2001 to August 2002. Two springs and one well near Betatakin Ruin, one spring is near Keet Seel Ruin, and one spring and one stream are near Inspection House Ruin. Water from all the sites is from the N aquifer, a regional sandstone aquifer that is the source of drinking water for most members of the Navajo Nation and Hopi Tribe in northeastern Arizona. Concentrations of dissolved solids, major ions, trace elements, and uranium were low at the six sites. Dissolved-solids concentration ranged from 94 to 221 milligrams per liter. Concentrations of dissolved nitrate (as nitrogen) were generally low (less than 0.05 to 0.92 milligrams per liter) and were within the range of concentrations at other N-aquifer sites within 20 miles of the study area. Water samples from Inscription House Spring, Navajo Creek Tributary (near Inscription House Ruin), and Keet Seel Ruin Spring contained indicators of human or animal wastes--fecal coliform and Escherichia coli bacteria.