Basin-scale evaluation

As Monitoring and Evaluation Advisers, La Trobe University is undertaking a Basin-scale evaluation of the contribution of Commonwealth environmental water to the environmental objectives of the Basin Plan.

Monitored outcomes at the Selected Areas will be compared to expected outcomes, to evaluate response. Over time, with increased data, models will be developed and used to predict ecological responses and measure the impact of Commonwealth environmental water across the Basin. La Trobe University will work with collaborators from the University of Melbourne, Monash University, University of Canberra, Griffith University and independent consultants to improve capacity to predict expected outcomes.

La Trobe University will report the outcomes of Commonwealth environmental watering at the Basin-scale to the Commonwealth Environmental Water Office annually, as well as cumulatively, over a five year period. Importantly, these reports will capture the lessons learnt from the watering actions undertaken to ensure a cycle of continual improvement in the management of Commonwealth environmental water.

2014-15 Basin-scale evaluation of Commonwealth environmental water

The Long Term Intervention Monitoring (LTIM) Project is evaluating the contribution of Commonwealth environmental water to achieving Basin Plan objectives. The first 2014–15 Basin-scale evaluation of Commonwealth environmental water was completed in 2016 and is now available from the Reports & Communication page or through Commonwealth Environmental Water Office (CEWO) website.

Some of the key findings of the report are:

1. Conditions across much of the Basin were considered dry in 2014-15. Within this context, Commonwealth environmental water actions contributed to the inundation of approximately 79,000ha of wetlands and floodplains across 11 river basins. Environmental flows comprised between 0% and 86% of total streamflow in the Basin’s rivers and in rivers such as the Gwydir, these flows reduced the duration of low flows. For example, at Allambie on the Gwydir, the duration of very low flows was reduced from 54% to 23% of the year while medium-low flows were reduced from 92% to 59% of the year.
2. Vegetation communities consistently responded to environmental flows, with increases in the extent and abundance of some plant species, reduced relative cover and diversity of non-native plants as well as shifts in the composition of vegetation towards assemblages characterised by a high abundance of emergent aquatic and semi-aquatic species.
3. Monitoring of fish populations from across the seven Selected Areas revealed very similar population structures between key species including Murray cod and Golden perch. Murray cod populations were characterised by larger numbers of young-of-year fish, but fewer old fish. Golden perch had few young-of-year fish but large numbers of older fish. The finding is interesting because these patterns were consistent across sites, suggesting that recruitment of these species may be taking place over much larger spatial scales than previously thought. This finding may influence the way that environmental flows are managed to support fish recruitment.
4. Across the Murray-Darling Basin, Wetlands of International Importance (i.e. Ramsar sites) and Directory of Important Wetlands in Australia (i.e. DIWA sites) benefited from Commonwealth environmental water, including the Cardross Lakes (DIWA), Hattah-Kulkyne Lakes (DIWA and Ramsar), Macquarie Marshes (DIWA and Ramsar) and the Gingham and Lower Gwydir (DIWA and Ramsar). All of these wetlands are nationally recognised for their environmental values and Commonwealth environmental water was associated with the provision of foraging habitat for waterbirds (Hattah and Gwydir) and frog breeding (Macquarie Marshes).

In 2014–15, 18 species of conservation significance were recorded at sites that received Commonwealth environmental water, including several threatened species. This includes, but is not limited to, the Regent Parrot and the Murray Hardyhead.

Basin matters

The Basin-scale evaluation will be based on outcomes for six ecological indicators, derived from the Basin Plan objectives. Collectively these indicators are referred to as Basin Matters and they are:

• Hydrology: Flow regimes and connectivity
• Ecosystem diversity
• Vegetation diversity
• River Metabolism
• Fish populations
• Generic diversity (e.g. frogs).