Dozens of people have been evacuated from their homes around Port Noarlunga and Old Noarlunga, south of Adelaide.
At 7:30pm last night, a flood emergency warning was issued for the area around the Onkaparinga River south of Mount Bold Reservoir
The message said water levels were continuing to rise in the Lower Onkaparinga River, and Port Noarlunga and Old Noarlunga could be impacted.
The river was expected to peak on Thursday morning.
SES spokesman Terry Dwyer told ABC news: "So there is a fair bit of water still to come and that's of concerns because Port Noarlunga and Old Noarlunga are taking an increasing amount of water down here," he told 891 ABC Adelaide's evening program.
'It is getting close to the stage that some will be evacuated.'