Insufficient subsurface characterization threatens the growth of several sustainable energy technologies and limits responsible management of water resources. Sustainable Subsurface Technologies (SSTs) such as geothermal power, carbon sequestration, and energy storage rely on transmitting and/or constraining fluids in the intertwining network of fractures and pore space in deep geological formations. Future growth of these industries will compete with the world’s increasing consumption of groundwater. In order to grow SSTs and protect Earth’s largest freshwater resource, subsurface reservoir characterization techniques must be advanced. Hawkins plans to develop and test a reservoir characterization technique that will combine the use of heat as a tracer and time-lapse subsurface imaging via Electrical Resistivity Tomography (ERT). If successful, “ERT thermal imaging” could be used by industry and water resource managers to monitor the migration of fluids in the subsurface and subsequently predict the spatial and temporal distribution of fluid flow.