Melbourne Water will implement 15 recommendations made by a review panel after an inquiry into flooding of the Maribyrnong River a year ago. 

Melbourne Water said today it accepts all the recommendations of the Independent Panel, which include improving its modelling and forecasting systems, factoring in climate change expectations for planning, and immediately making use of a modern flood model to set new design flood levels for flooring. 

It also agreed to use a new hydraulic tool to determine how effective downstream compensatory works are for the controversial Flemington floodwall.

"We will work to implement them as quickly as possible,” Melbourne Water said. Seven of the recommendations have already been implemented, a spokeswoman says.

“Melbourne Water accepts every finding and will be working on them as soon as we can,” she said.

More than 500 homes and businesses near the Maribyrnong River, which runs through Melbourne's north-west, were inundated in October 2022. There was little warning for residents, with some receiving text messages in the night. 

Melbourne Water’s independent review, led by former Supreme Court Judge Tony Pagone, examined the causes and contributors to the flood event in the urban catchment.  

The final report says a failure to include consideration of the expected impact of climate change in current flood modelling is “likely to have far reaching negative long-term impact” because the models determine planning controls. 

“Buildings potentially within flood plains are at increasing risk of (repeated) flooding into the future if, for example, required finished floor levels of new buildings...are determined using the conclusions of flood models that do not consider climate change,” it said.

The Panel held public consultations in July this year, heard from interested parties and members of the community detailing their experiences of the floods and considered the 63 submissions. 

Aside from private houses, the floods affected 30km of roads and stormwater drains, 70km of footpaths, playgrounds, public toilets and BBQs, park lighting, sport pavilions, and community groups. The council removed around 150,000 cubic meters of mud, silt, household material and other flood debris.

Separately, a parliamentary committee is investigating Victoria’s preparedness and response to the October floods covering the Avoca, Barwon, Broken, Campaspe, Goulburn, Loddon, Maribyrnong, and Murray rivers.

Here are the 15 recommendations Melbourne Water says it will implement: 

• Review flood models every five years and update them at least every 10 years and after the occurrence of a major flood.  
• Ensure that rainfall runoff and flood models are calibrated to observed flood information.
• Ensure rating curves, which represent the relationships between river levels and corresponding river flows, extend also to rare and extreme flood events
• Take account of the best estimates of the impact of climate change when setting flood levels for planning and development and the application of the Land Subject to Inundation Overlay.
• Adopt tools which enable forecasts to be made within 60 minutes or less.
• Use new hydraulic model, to become available in April, to determine impact of the Flemington Floodwall and the efficacy of the associated downstream compensatory works.
• Commission an independent expert review and audit of its forecasting system so accuracy, warning times and model run times are improved.
• Take account of changes in land use when setting flood levels for planning and development and the application of the Land Subject to Inundation Overlay.
• Immediately update the Mid Maribyrnong flood model with a modern two dimensional flood model developed in accordance 120 Official with Melbourne Water guidelines and use this model to set new design flood levels
• Have a protocol that enables flood forecasting at intervals at less than two hours when prudent to do so by reason of the responsiveness of the catchment for significant events.
• Consult with the Bureau of Meteorology to develop rainfall forecasts more frequently than six hours.
• Seek Minister for Planning approval to apply interim planning controls designating the Land Subject to Inundation Overlay in locations where flooding occurred
• Investigate how it came to be satisfied with a reduction of flood levels and finished floor levels at the Rivervue Retirement Village as specified in the endorsed plans dated 2 June 2009.
• Investigate the feasibility of installing one way valves on the outlets from the street and yard drainage from Evergreen Avenue and Rivervue Retirement Village
• Investigate long-term sustainable flood mitigation options for the Maribyrnong River

See the review here.