Australia's Brisbane residents have breathed a sigh of relief after the surging Brisbane River peaked at about 4.46 meters around 5 a.m. (local time) on Thursday -- well below forecasts of 5.5 meters and the 5.45 meter peak in 1974, local media reported on Thursday.

"The Brisbane River has now reached its peak," police said in a statement around 5 a.m. (local time).

"Water levels will remain high for the rest of the day. Current predictions indicate that floodwater will slowly recede over the weekend."

Just before 5:30 a.m. (local time), a Bureau of Meteorology spokesman told the Australian Broadcasting Corporation (ABC) the river was current "at or near its peak."

"Hydrologists, they do believe it is at or near its peak currently," forecaster Brett Harrison said.

"We still expect it to be above major flood levels until sometime during Friday and remain high over the weekend," Harrison said.

The suburbs identified as being the worst-hit by the flooding are Brisbane City, St Lucia, West End, Rocklea and Graceville.

Brisbane Lord Mayor Campbell Newman said there was a lot of water in the Central Business District (CBD), but the lower than expected peak had saved many businesses and high-rise apartment buildings.

He said revised figures, based on a 4.6 meter peak, suggested 11,900 properties would be fully flooded and 14,700 partially affected.

At that level, 2,500 businesses would be fully affected, and another 2,500 partially affected, Newman said.

"We all now have to rally together to help these people clean up, the ones that have suffered impacts," he told the ABC.

He said drinking water supplies in the Brisbane City Council local government area were safe and secure.