Information systems can be an integral part of environmental management practices enacted in the pursuit of environmental sustainability outcomes. We analyse the specific case of an environmental information system developed by a South Australian environmental regulator. The information system was intended to support efforts to sustain water quality by controlling the discharge of ‘greywater’ from vessels using South Australia’s inland waters. We conceptualize the information system as the outcome of a continuing, though non-deterministic, trajectory of interacting material and human agencies, in the form of technology and routines. In our analysis, we trace how these basic building blocks of the system came to be, and how they shaped the emergent environmental information system in particular ways.