Airborne electromagnetic (AEM) and magnetic survey data were collected during October 2015 along 769 line-kilometers over a 160-square-kilometer area that includes the Big Sioux aquifer between Sioux Falls and Dell Rapids, South Dakota, USA. Data were acquired with the CGG Resolve frequency-domain helicopter-borne electromagnetic system along with a cesium vapor magnetometer. Files included in this data release are: (1) raw and processed AEM and magnetic data; (2) processed AEM resistivity-depth inversions, and (3) a contractor’s report describing survey parameters, field operations, quality control, and data reduction procedures.