The coalition and Greens have teamed up to expand the scope of a proposed inquiry into last year's floods after concerns about Melbourne Water's review into the Maribyrnong River floods.
Questions have been raised about the review's scope and independence.
Nick Wimbush stepped aside as the review's independent lead after it was revealed he was the sole member of a Moonee Valley planning panel in 2015 when Melbourne Water requested flood overlay changes for part of the Rivervue Retirement Village.
Dozens of those properties were inundated when the Maribyrnong broke its banks in October.
Emergency flood warnings and potential mitigation measures are not being assessed as part of the review, with the focus instead on the impact of the Flemington Racecourse levee and whether flood modelling should change.
Separate flood inquiry motions were introduced by the coalition and Greens in the upper house earlier this month but they've joined forces following talks.
The opposition has agreed to pass the Greens' amendments to its statewide flood inquiry motion, which focuses on the Avoca, Barwon, Broken, Campaspe, Goulburn, Loddon, Maribyrnong and Murray rivers.
The Greens amendments expand the scope of the proposed inquiry to include investigating the decision making behind the Flemington flood wall and climate mitigation in flood planning.
With 18 upper house MPs between them, only three crossbenchers would be needed for the motion to pass.
Victorian Greens Deputy Leader Ellen Sandell said the community would now get the flood investigation it has been asking for.
"The Victorian Labor government has tried to sweep important questions about the flood under the carpet, but they can't keep avoiding criticism or deflecting blame," she said.
"Parliament will begin a broad-ranging inquiry into Victoria's recent floods, including the Maribyrnong flood, which will look into key questions such as why the racecourse flood wall was built, why bad planning decisions continue to be made by state governments, and how we can prepare our communities for future climate disasters."
Premier Daniel Andrews has previously flagged his government would not support a separate parliamentary inquiry, describing the motions as a political game.
The motion would require the Environment and Planning Committee to report its findings by June 30, 2024.
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