The Platypus, like other native mammals, has been affected by European settlement. Degradation of natural habitats and landscapes has reduced population numbers and most likely contributed to the extinction of wild Platypus in South Australia. A constructed wetland located at Warrawong Sanctuary in South Australia was assessed for its capacity to sustain a resident population of Platypus. This study incorporated surveys of riparian vegetation, water quality and the primary food source of Platypus (macroinvertebrates). The constructed system consisted of four main pools and several riffle zones; the vegetation was mostly native including Eucalyptus and Acacia species. Water quality was poor, with elevated levels of nutrients and turbidity. Macroinvertebrates consisted of a large variety of Platypus prey items. The macroinvertebrates identified suggest that the water quality was poor given the average SIGNAL score obtained. These indicators associated with the quality and structure of the ecosystem at Warrawong were comparable to natural wetlands. Although the system was found to be ‘degraded’, it was still able to sustain a functional population of Platypus over a 20 year period.