Ground-water data that can be used for futher hydrologic studies in the San Juan structural basin of New Mexico are reported. Descriptions and a location map of 64 observation wells, a list of water levels measured in the observation wells, water-level hydrographs of 32 wells, 15 partial chemical analyses of water samples from wells, and descriptions and a location map of 264 potential observations wells are included. The latter are wells for which good records exist. Their potential for use as observation wells needs to be verified in the field. (USGS)