Controlled source audio-frequency magnetotellurics (CSAMT) data were collected in the Big Chino Valley and Paulden areas, Yavapai County, Arizona, to better understand the hydrogeology of the area. CSAMT data provide vertical cross-section (profile) data about the resistivity of the subsurface, which may be related to lithologic boundaries and (or) grain-size distribution in the subsurface. CSAMT involves transmitting a current at various frequencies in one location, and measuring resistivity differences between electrodes spaced along a receiver line several kilometers from the transmitter. . Big_Chino_Valley_CSAMT_RawData.zip: These are text files output by the data-collection instrument (GDP-32, Zonge International, Inc.) used in the inversion. These data may be useful for testing alternative inversion schemes. The zip file contains one text file per line.