Potential issues have been highlighted in an inquiry into flooding in Melbourne. 

The Greens have called for a parliamentary inquiry into last year's Maribyrnong flood after the head of an ongoing Melbourne Water review stood down over conflict of interest concerns. 

Last October, homes and businesses in Melbourne's west were inundated as the Maribyrnong River rose during a flood event. 

Some residents say that a flood wall around Flemington Racecourse exacerbated the disaster, and raised questions about the effectiveness of the early-warning system used in the area.

Melbourne Water announced last year that it would run an independent review into the flood event headed by planning and environment expert Nick Wimbush.

It said it would review the “causes and contributors to the Flood Event in the urban catchment, including any potential impacts of the Flemington Racecourse Flood Wall on the extent and duration of the Flood Event” and “any impact of prior works or activities in the urban catchment on flood levels and extent during the Flood Event”, as well as “whether any other matters may have significantly contributed to the Flood Event”.

The terms of reference specifically list a number of areas that are out of the scope of the review, including any specific policy responses, future potential mitigation measures, overall emergency responses, flood recovery, and any broad planning matters including decisions, frameworks and processes. 

Melbourne Water has now confirmed that Mr Wimbush is stepping aside from his role due to potential perceived conflicts of interest.

Mr Wimbush was the chair of a Moonee Valley City Council planning panel when it considered a change to the planning scheme in 2015. 

“Mr Wimbush's appointment met all probity and appointment criteria and he was eminently qualified to undertake the role,” a Melbourne Water spokesperson said in a statement.

‘This position was confirmed on review by an independent probity advisor before his appointment.

“Melbourne Water is determined to demonstrate the integrity of the review process, we have taken this step mutually with Mr Wimbush.

“This is necessary so as not to distract from the important work of the review.”

But Greens MP Ellen Sandell says a parliamentary inquiry is needed to fill the potential gaps in the review.

“It leaves a lot to be desired,” she said.

“It leaves out really important questions, like why were flood walls allowed to be used in the first place and why early warning systems didn't work.

“And that's why we need a proper parliamentary inquiry.”

Victoria's Water Minister Harriet Shing has accepted Melbourne Water's handling of the review.

“I'm not going to run a running commentary on the nature of this review,” she said.

“The word ‘independent’ is really important here, it needs to take place without any interference from government.”