The Arroyo Hondo ground water study reveals a complex, three-dimensional ground water system with multiple hydrostratigraphic units and aquifers. Distribution of the geologic and hydrostratigraphic units is presented through geologic maps and seven detailed cross sections that depict the distribution of geologic and hydrostratigraphic units, well data, surface water features, water levels, faults, and zones of fracturing and sediment layers in volcanic rocks. Cross sections are constructed both parallel and perpendicular to regional ground water flow and illustrate aquifers in the context of the geologic framework, the Rio Grande and the Rio Hondo, local acequias and other surface water features.