Prior to European settlement of the Adelaide Plains, winter rains over the catchment of the River Torrens created large seasonal inflows of fresh water into the Reedbeds wetlands, which drained north into the Port River and south to the Patawalonga River. In their natural state, the interconnected creeks and channels of the Port River estuary and Barker Inlet were surrounded by mudflats, mangroves, and saltmarshes colonised by samphires. Many of these remain, although the water flows have changed significantly. Tidal movement has a substantial influence on the ecology of the estuarine area's flora and marine fauna. Flows occur from the north (via Outer Harbor) and south (West Lakes, which draws in seawater via an engineered tunnel at Grange).