https://www.somerset.qld.gov.au/downloads/file/99/135-roads-and-bridges The Wivenhoe Bridge was located very close upstream from the current dam wall.
The Next map is from the key map, and the following is detail from that map.
https://gisservices.information.qld.gov.au/arcgis/rest/directories/historicalscans/cad_scans/1cad- map-key-map-40chain-moreton-ag2-series.jpg
https://gisservices.information.qld.gov.au/arcgis/rest/directories/historicalscans/cad_scans/cad- map-40chn-moreton-ag2-sh4-west-1927.jpg
I believe the “Bridge” marked on this map is the Wivenhoe Bridge.