Victoria's preparation and response to last year's major floods will be examined through a new parliamentary inquiry.
An upper house motion to establish the inquiry passed unopposed on Wednesday morning after the coalition and Greens teamed up to expand its scope.
Melbourne Water has begun a review into the Maribyrnong River floods, which inundated more than 500 properties in October.
But the parliamentary inquiry will have a statewide focus taking in the rivers Avoca, Barwon, Broken, Campaspe, Goulburn, Loddon, Maribyrnong and Murray.
It will look at the causes of the flood event, the effectiveness of early warning systems, and resourcing of the State Emergency Service and adequacy of its response.
In addition, the controversial Flemington Racecourse flood levee and planning decisions will be put under the spotlight as part of amendments negotiated by the Greens.
Nick Wimbush stepped aside as independent lead of the Melbourne Water review after it was revealed he was the sole member of a Moonee Valley planning panel in 2015.
That panel requested flood overlay changes for part of the Rivervue Retirement Village, where dozens of properties were inundated.
Melbourne Water denies Mr Wimbush investigated or considered any submissions relating to the site.
The Maribyrnong River review is considering the impact of the racecourse levee and flood modelling but its terms of reference don't allow for scrutiny of emergency flood warnings and mitigation measures.
The opposition's upper house leader Georgie Crozier said the parliamentary inquiry would allow flood victims across the state to come forward to talk about their experiences.
"(It's) terribly important that they get answers to those questions that so far have been largely avoided," she said.
"This motion is much broader because of the true devastation and very significant impacts that are still there."
Victorian Greens deputy leader Ellen Sandell accused Labor of trying to sweep criticism of its handling of the floods under the carpet.
The inquiry will "shine a light" on key decisions and concerns of the community, she said.
Before the motion was debated, Premier Daniel Andrews said he was not "so much fussed" by the optics of Labor not supporting the motion after previously describing it as a political game.
"I've got a lot to get on with," he said.
The Environment and Planning Committee is due to report back with findings and recommendations by mid-2024 but Ms Crozier said its deadline could be extended if necessary.
