This map (scale 1:125,000) is a preliminary assessment of the availability of ground water in the Piscataqua and coastal river basins in New Hampshire. It is a generalization of several hydrogeologic factors and provides a guide for ground-water exploration, which is useful in water- and land-use planning. The best aquifers in the basin are deposits of stratified sand or sand and gravel of Pleistocene age. Large aquifers of this type occur in places in the major river valleys and in interstream areas within the coastal plain. Ground water is generally of good chemical quality. Iron and manganese in concentrations greater than the recommended limits for drinking water suggested by the U.S. Public Health Service, however, are not uncommon. (Woodard-USGS)