The state government is expected to go back to the drawing board to update technical information on the proposed Goulburn River Constraints project, after determining Murray-Darling Basin Authority modelling is 'not fit for purpose'.
The government is believed to be revisiting a Department of Environment, Land, Water and Planning tender document, from 2019, behind the delivery of Stage 1A of the Victorian Constraints Measures Program.
The MDBA'S Constraints Management Strategy attempts to relax or remove constraints to the delivery of environmental water for the purposes of piggybacking managed releases from dams on top of existing rainfall and flows in the Southern-Connected Basin.
"The MDBA in the past have undertaken some technical work to inform modelling, which was not fit for purpose for informing decisions around constraints relaxation," the tender document states.
"Victoria believes it needs to reduce the uncertainty in the technical information in order to have meaningful conversations with potentially affected landholders in latter stages.
"As part of Stage 1A, it is proposed that technical information will be updated to address these critical gaps in survey data; availability and quality of hydrologic and hydrodynamic modelling."
The government has set up a 25 member committee, under former Victorian National Party leader Pat McNamara, to advise it on the state's proposed constraints measures program.
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The committee is looking at the feasibility of allowing higher environmental water flows in the Goulburn River from Lake Eildon to the River Murray, and in the River Murray downstream of Lake Hume.
The tender document found conceptual business cases, used to develop constraints measures, didn't include climate change scenarios or adequate information on the costs, risks and benefits of implementation.
"Not all the business cases had community involvement and hence community are sceptical and do not know how they will be treated," the document said.
"Furthermore, technical investigations and reviews have shown deficiencies in data.
"It is appropriate that the project be reset and to provide a forum for the exchange and testing of views for it to have the best chance of success."
NSW, Victoria and South Australia have put forward a package of 36 supply measures to support the health of local rivers and wetlands along the Murray River and its tributaries.
The projects make up the Sustainable Diversion Limit Adjustment Mechanism (SDLAM) amendment to the Basin Plan, which received bipartisan support from the Australian Parliament in May 2018.
The projects reduce the amount of water for the environment that needs to be recovered and improves environmental benefits in the Basin.
"Of the 36 supply measures there are five projects that are also constraints measures. Victoria has also put forward the Goulburn constraint measure project," the tender document said.
"This project was not formally notified as a supply measure, however, the success of other constraints projects rely on the higher operational limit on flow rates for environmental water delivery nominated in the Goulburn project."
The business case applies to the 440-kilometre section of Goulburn River extending from Lake Eildon at the upstream end, to its connection with the River Murray near Echuca.
It seeks to relieve constraints on the Goulburn River, maximising environmental outcomes while minimising the cost of higher in-channel flows.
"The business case assesses the potential impacts to private and public land and assets arising from higher in-channel river flows and examines possible mitigation options and costs," the document said.
A Department of Environment, Land, Water and Planning spokeswoman confirmed the current modelling was not 'fit for purpose.
"Before any measures are put in place communities need to be appropriately engaged, cost and benefits clear and any risks to communities or river health managed," the spokeswoman said.
"Victoria's position has always been that we won't flood private land without consent, or compulsorily acquire land or easements - and that position won't be changing."
The Victorian and NSW governments commissioned an independent review (Wilson review) of the MDBA's modelling, underpinning higher environmental flow delivery in the southern-connected Basin.
The review was in response to community concerns about the impacts of proposed higher flows on land, businesses, and local infrastructure.