The Goulburn to Murray trade review Scientific Advisory Panel (the Panel) has prepared three reports, covering detailed results and analysis of the lower Goulburn River Research and Investigations Program undertaken during 2023–24, and interpretation of the outcomes over the combined three years from the start of the program (2021–24).

The program is designed to assess the environmental performance of the long-term Operating Rules for the lower Goulburn River and to determine whether the rules are working as intended to prevent environmental damage from sustained high flows over summer and autumn.

Climatic and flow conditions throughout 2021–24, including record breaking floods in spring 2022 and summer 2024, saw relatively low demand for inter-valley trade (IVT) deliveries from the Goulburn River to the River Murray during the peak irrigation period (December to April).

This has meant the Panel could not directly assess the potential impacts of the full delivery of summer pulses allowed under the rules, as these did not occur during the 2021-24 research and investigations program.

However, these wetter seasonal conditions did provide an opportunity to consider how the lower Goulburn River responds when there are limited summer and autumn flows, and when prolonged baseflows at or below the maximum specified by the operating rules are delivered throughout the summer-autumn period. The Panel were also able to examine the effects of natural flooding on environmental outcomes. This is invaluable information for understanding how the river may respond over time in future wetter periods under the long-term operating rules.

The results provide some early indications of positive environmental responses in the lower Goulburn River, as summarised below:

Bank condition

Successive years of low summer and autumn baseflows have helped to stabilise the bank and reduce erosion and notching. The report identifies a potential future risk of a cumulative negative impact over time at specific bank elevations if successive pulses are delivered in full, every year (i.e. three pulses across summer and autumn, to the maximum size allowed). However, this negative impact hasn't occurred in the 2021–24 survey period.

Bank vegetation

Successive years of low summer flows have allowed for gradual regeneration of bank vegetation on the lower bank zones. There was a marked increase in the cover of all vegetation, particularly inundation-tolerant plants. This was a result of the low summer flows after the flood in spring 2022, when a greater growth response was observed compared with earlier non-flood years. The summer 2024 flood occurred during the peak growth season and negatively impacted this positive trend. However, bank vegetation quickly recovered following water recession, indicating a level of resilience that was probably fostered by successive years of low summer flows and spring freshes.

Native fish

A decrease in the abundance of some native fish species was observed, likely due to impacts from the widespread flooding in 2022. This decrease in abundance indicates that some fish, especially more mobile species such as Murray cod, might have moved to other reaches in response to the flooding and reduced water quality that followed flood recession.

Macroinvertebrates

More shrimp and prawns were observed over the three years compared to previous years, suggesting a positive response by macroinvertebrates to low summer baseflows that align with environmental flow recommendations. Based on available information, long-term trajectories for macroinvertebrates are likely to be positive as long as the demand for summer IVT flows remains low.

Platypus

Environmental DNA surveys over the past three years have enabled the mapping of platypus distribution in the lower Goulburn River system and established a baseline for monitoring changes in future. Based on the results, platypus continue to be widely distributed along the lower Goulburn River, including within lagoon habitats.

Additional research and investigations were also undertaken in the Lower Broken Creek and Campaspe River to benchmark the environmental condition.

For more information about the 2021-24 research and investigations program, including detailed results and analysis, see the full reports below:

 Scientific Advisory Panel Annual Report Number 3-C: Summary report for the 2021–24 lower Goulburn River research and investigations program (PDF, 1.2 MB)

 Scientific Advisory Panel Annual Report Number 3-A: Detailed results from the 2021–24 lower Goulburn River research and investigations program (PDF, 18.5 MB)

 Scientific Advisory Panel Annual Report Number 3-B: Detailed results from 2021–24 lower Broken Creek and Campaspe River research and investigations program (11.8 MB)

 Frequently Asked Questions: The 2021–24 Scientific Advisory Panel Reports (156 KB)

You can read 2021–22 Scientific Advisory Panel Reports on the Victorian Water Register website here, and you can read the 2022–23 reports here.

The Panel will continue the research and investigations program through to 2028 to assess the environmental performance of the long-term operating rules to gather evidence to support any recommendations regarding future refinements and improvements to the rules.

You can read more about the Goulburn to Murray trade review and the Victorian Minister for Water’s decision on long-term trade and operating rules here.