The Monument Valley and the northern part of the Black Mesa areas include about 2,700 sq mi in northeastern Arizona and are entirely in the Navajo and Hopi Indian Reservations. The main source of water is from the several aquifers that are made up of one or more formations. The aquifers are stacked one on the other and generally are not hydraulically connected. Information on the maps includes depth to water, altitude of the water level , and chemical quality of the water. Scale 1:125,000. (Woodard-USGS)