The Goulburn to Murray trade review Scientific Advisory Panel (the Panel) has completed their 2022–23 annual report describing the environmental outcomes from the second year of a three-year environmental monitoring program. The monitoring program is designed to assess the environmental performance of the new long-term Operating Rules for the lower Goulburn River, and to determine whether the rules are working as expected to prevent the kinds of environmental damage seen in previous years due to sustained high flows over summer and autumn.

The wet conditions in 2022–23 resulted in low demand for inter-valley trade (IVT) deliveries. This means regulated flows in the lower Goulburn could be managed within or below the maximum allowed baseflows and pulse limits set by the rules. The largest driver of environmental change during this time period was the major flood event in the Goulburn River in spring 2022.

However, the 2022–23 results for the lower Goulburn River do provide some early indications of positive environmental response to successive years of lower summer and autumn baseflows in each of the following core themes:

Bank condition: Successive years of sustained, low summer and autumn baseflows have stabilised the bank and led to reduced rates of erosion and less notching overall. In 2022–23, the spring flood resulted in widespread high-magnitude erosion (up to 25 cm) and deposition (up to 20 cm deep) across riverbank survey locations. Erosion was greatest where banks had been damaged from past high, sustained IVT flows. Impacts on bank condition of the 2023 autumn IVT pulse were minor compared to the flood.

Bank vegetation: There was a marked increase in the cover of all vegetation, particularly inundation-tolerant plants. This was a result of the low summer flows preceded by the spring flood. This indicates a greater growth response compared with earlier non-flood years. However, the magnitude and duration of the spring flood exceeded the tolerances of some species, including common tussock grass and rushes.

Native fish: A decrease in the abundance of some native fish species was observed due to impacts from the widespread flooding in spring 2022. These results 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: An increased abundance of shrimp and prawns was observed in the last two years compared to previous years. This suggests a positive response by macroinvertebrates to low summer baseflows that align with environmental flow recommendations.

Platypus: The 2022–23 surveys confirmed the findings of the previous year that platypus continue to be widely distributed in the lower Goulburn system, albeit in low numbers. There is little information on platypus numbers in the lower Goulburn River.

Baseline monitoring of the environmental condition of the Lower Broken Creek was also undertaken, with no IVT deliveries occurring via the Lower Broken Creek in 2022–23.

For more information about the 2022-23 results and analysis, see the full reports below:

 PDF The 2022-23 Scientific Advisory Panel Executive Summary Report Number 2-A lower Goulburn River Research and Investigations Program (1,500 KB)

 PDF The 2022-23 Scientific Advisory Panel Annual Report Number 2-A lower Goulburn River Research and Investigations Program (9,410 KB)

 PDF The 2022-23 Scientific Advisory Panel Report Number 2-B – lower Broken Creek research and investigations program 2022-23 (7,620 KB)

 PDF Frequently Asked Question – The 2022-23 Scientific Advisory Panel Reports (76 KB)

You can read 2021–22 Scientific Advisory Panel Reports on the Victorian Water Register website here.

The Panel will continue to use monitoring results to assess the environmental performance of the long-term operating rules over the next year of currently funded monitoring, gathering 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.