What is the SRW MID2030 modernisation project?
Irrigation district modernisation projects improve water system efficiency, by reducing the volume of water that is required to support delivery of water to existing entitlement holders – by reducing the volume is lost through seepage, leakage, and evaporation and that is spilled through irrigation channel outfalls into wetlands and rivers.
The SRW MID2030 project replaced the district’s ageing channel irrigation network with a modernised system.
Further information on the MID2030 modernisation project can be found at Macalister Irrigation District Modernisation | Southern Rural Water or at Investment in irrigation efficiency.
What has the VEWH requested?
VEWH submitted a request to the Minister for Water, under section 48K of the Water Act, for an amendment to the Thomson/Macalister System Environmental Entitlement 2024 to include additional mitigation water to offset the impacts on Heart Morass from irrigation modernisation.
What is mitigation water and why did the MID 2030 Modernisation project need to provide mitigation water to the environment?
Sometimes water in irrigation channels is discharged through outfalls into wetlands and rivers and, over time, provides an important environmental benefit. Heart Morass is a floodplain wetland (part of the Lower Latrobe wetlands) and is one of the sites that previously benefited from spilled water.
Improving the efficiency of the irrigation systems reduces the volume of water that is spilled through these outfalls. To ensure the environment still benefits, some of the recovered water is set aside for the environment to maintain the areas of high environmental value. This is known as mitigation water.
SRW developed Environmental Watering Plans (EWPs) for sites impacted by modernisation works. The EWPs assessed environmental values and calculated the expected volume of mitigation water required to offset the impact of the implementation of the MID2030 Project.
How is water sourced to meet the additional entitlement?
Mitigation water is sourced from the water recovered from irrigation modernisation works. The 400 ML LTAAY has already been set aside by SRW and is drawn from the overall volume of water recovery achieved and audited by the project to date. The VEWH has applied to add this water to its existing entitlement.
Water recovery associated with MID2030 Project, including mitigation water, has been independently audited to ensure the entitlement being issued reflects actual water savings that have been achieved.
Total Project water recovery is the total (gross) volumes saved, less the volume of mitigation water required.
How much mitigation water is required?
EWPs developed for the Thomson River and Macalister River mitigation water sites identified that a volume of 1,814ML LTAAY was required to offset the impact to these sites from the MID2030 modernisation project.
The Thomson/Macalister System - Mitigation Water Environmental Entitlement was established in 2024 and provides this water as 1568.80 ML of high-reliability entitlement and 691.8 ML of low-reliability entitlement, which is equivalent to the 1814 ML LTAAY.
Heart Morass was a third mitigation water site for which an EWP was prepared. At the time that the entitlement was established in 2024, there was uncertainty about the mitigation water requirement for the Heart Morass wetland, so the environmental entitlement was issued without a provision for Heart Morass.
In anticipation of a further volume being required for Heart Morass, Southern SRW set aside water while the Heart Morass EWP was updated and finalised.
How will the mitigation water be used?
Planning for the use of the mitigation water entitlement will be incorporated into existing processes, using the Heart Morass EWP as a guide.
Each year, VEWH prepares a Seasonal Watering Plan to guide decisions about delivering water for the environment across Victoria. It outlines how the available environmental entitlements will be used across the state under different climate scenarios and tells VEWH’s program partners, Traditional Owners, stakeholders and communities what to expect during the water year.
To ensure the water is used for the most benefit, VEWH develops the Seasonal Watering Plan in close partnership with waterway managers – who engage extensively with their communities, including Traditional Owners, storage managers, land managers, and scientists – to prepare seasonal watering proposals that form the basis of the plan.
This planning process is thorough, and is informed by scientific evidence, biocultural knowledge, local inputs and on-ground evaluation.
For the Thomson/Macalister system, VEWH works with the West Gippsland Catchment Management Authority to plan how environmental water (including mitigation water) is used each year.
What is the Water Savings Protocol and how is it used to calculate water recovery?
All water savings from major irrigation modernisation projects in Victoria, including the MID 2030 Project, must be estimated and audited in accordance with the Victorian Government Water Savings Protocol.
The Water Savings Protocol is the technical manual for estimating water savings. It reflects current best practice for and is updated periodically to reflect improvements in technology and any changes in the understanding of irrigation system losses.
It also sets out roles and responsibilities and specifies the audit process, including the role of auditor to independently verify water savings estimates.
Estimating water recovery using the methods in the Water Savings Protocol ensures that the estimate is calculated in a consistent and transparent manner using the most current scientific information. This means it can be used as evidence to issue water recovered as entitlements.