In collaboration with the Universidad Nacional Autónoma de México UNAM, Chucho Ocampo is using subsurface imaging methods such as ground-penetrating radar (GPR) to uncover a hidden 17th-century water infrastructure. Because scientists conduct their measurements in public spaces, the role of the public in these efforts is of particular interest. The performance of public measurements taps into collective memory and attention to traces, as well as the contested political relevance of water infrastructure management.