For the investigation of recharge and flow patterns in the Roswell (N.M.) artesian basin we have used different approaches. Isotope determinations (tritium, deuterium, and oxygen-18) have been made as a function of time and space. Observation well levels, springflow, and precipitation have been analyzed by stochastic and numerical methods. A hydrogeologic survey of representative springs in the recharge zone along the western flank of the basin has been performed. A detailed discussion of various phases of this work has been given in separate Partial Completion Reports. In the present report, we summarize and integrate the results. An updated listing is presented of tritium activity determinations in precipitation, surface water, springs, and groundwater from over 120 sampling points in the basin. Several distinct recharge components have been recognized in the basin. The accumulated evidence indicates that recharge to the Principal Aquifer from the surface of the Principal Intake Area has been overestimated in the past. In order to account for the groundwater budget of the basin, substantial contributions from deep leakage must be included. These are primarily supplied by the Glorieta Sandstone and the Yeso Formation of the western basin flank.

Project No. A-055-NMEX