The Bremer River at Ipswichâ '' 30 k west of Brisbaneâ '' reached a height of 19.4 m on 12 January , flooding the central business district and at least 3,000 houses . The Bremer River at Ipswich , 30 k west of Brisbane , reached a height of 19.4 m on 12 January , inundating the central business district and at least 3,000 houses .