Urban freshwater wetlands have been identified as a potential source of mosquitoes of pest and public health concern in Australia. Mosquitoes most commonly associated with these habitats include Anopheles annulipes, Culex annulirostris, Culex quinquefasciatus, Coquillettidia linealis and Mansonia uniformis. However, adaptive management of freshwater wetlands for wildlife conservation or vegetation management can alter the local environmental conditions and may provide opportunities for other mosquito species to exploit these habitats. A series of small wetlands at Sydney Olympic Park, NSW, were drained in spring 2016 and allowed to refill via rainfall to improve conditions for the endangered green and golden bell frog Litoria aurea. Below-average rainfall was experienced that summer and the wetlands did not fully refill until early autumn. Surprisingly, immature stages of the estuarine mosquito, Aedes vigilax, were observed in the freshwater wetlands in exceptional abundances during this period. Adjacent to these freshwater wetlands there are extensive saltmarsh and mangrove habitats where highly abundant populations of Ae. vigilax are common. Observations of use of freshwater habitats by this estuarine mosquito have implications for urban freshwater wetland management and rehabilitation strategies, which currently do not consider the potential pest and public health issues associated with estuarine mosquitoes.