There is a need to sustainably managed our groundwater systems. But management requires measurements. We have been working over the past eight years to develop ways to use geophysical data - acquired using a system flown with a helicopter - to obtain the measurements needed in California. We have used the geophysical data to image 300 meters below the ground surface, mapping out features such as the saltwater intrusion along coastlines, the sediment types in the Central Valley, and the pathways along which the groundwater systems are being recharged, refilled with water. Advancing the adoption of geophysical data can revolutionize the approach to sustainable groundwater management.