Commonwealth Environmental Water Office Long-Term Intervention Monitoring Project Murrumbidgee River System evaluation report 2014-17

2017
Prepared by: Wassens, S., Spencer, J., Wolfenden, B., Thiem, J., Thomas, R., Jenkins, K., Brandis, K., Lenon, E., Hall, A., Ocock, J., Kobayashi, T., Bino, G., Heath, J. and Callaghan, D.
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About the document

This report presents results from the third year of monitoring and evaluation in the Murrumbidgee river system under the Commonwealth Environmental Water Office’s Long Term Intervention Monitoring (LTIM) Project. The report evaluates the contribution water for the environment has made to environmental outcomes in 2016-17, complementing monitoring and evaluation undertaken from 2011-2016.

Key environmental outcomes identified through the Murrumbidgee LTIM Project include:

  • Delivery of over 241,000 ML (241 GL) of water for the environment as part of 13 water release events across the Murrumbidgee River catchment. Water releases targeted the main river channel and key floodplain and wetland habitats, anabranches and creeks.
  • Water for the environment was released from winter 2016 to the Lowbidgee floodplain to support habitat for the threatened southern bell frog and other floodplain dependant species.
  • Watering actions were paused in early spring due to widespread rainfall, significant river rises and extensive floodplain inundation.
  • Watering restarted once the floods receded. This helped native fish survive as the floodwaters went down (and managed conditions which can result in ‘blackwater’ events). The watering action is estimated to have restored dissolved oxygen levels to non-lethal conditions (for fish) 18 days earlier than would have occurred without water for the environment.
  • Water released into wetlands supported native bird species including the endangered Australasian bittern, vulnerable blue-billed duck, freckled duck, magpie goose and international migratory birds including the marsh sandpiper and sharp-tailed sandpiper. The water contributed to successful breeding outcomes for over 30 waterbird species across the Lowbidgee floodplain. By extending the duration and depth of wetland inundation and providing foraging habitat, the water supported fledging of colonial‑nesting waterbirds (estimated to be over 65,000 waterbird nests) at six colony sites.
  • Frogs, fish and freshwater turtles benefited from the wetland watering. Six frog species were recorded, including large numbers of southern bell frogs at Nap Nap swamp. Three species of freshwater turtles (broad shelled turtles, eastern long necked turtle and Macquarie turtles) were recorded at wetlands that received environmental water. 
  • Eight native and five exotic fish species were recorded. This included juvenile silver perch and flathead gudgeon collected at Yarradda Lagoon for the first time since monitoring began in 2014. This demonstrated the value of repeat watering actions to improve refuge habitat for native fish, frogs and turtles.
  • In the mid-Murrumbidgee River, vegetation in wetlands receiving environmental water at least once over the past three years remains in very good condition. Wetlands that did not receive environmental water over the past three years had lower diversity of water dependent species and higher abundance of exotic weed species. Water-dependent species at Yarradda Lagoon in the mid-Murrumbidgee River increased following watering events in 2014-15 and 2015-16. Key species including spiny mudgrass, tall spike rush, and fringe lily were re-established.
  • Overall, environmental water contributed to additional inundation of over 80,000 hectares of wetland and floodplain habitats in the Murrumbidgee River catchment in 2016-17.

The report is presented in three parts:

  • An executive summary;
  • A non-technical synthesis section; and
  • A technical appendices section which provide detailed methods, analyses and results for each indicator.

This report is the third of five to be produced for the Murrumbidgee Selected Area under the LTIM Project, with monitoring and evaluation being undertaken from 2014-15 to 2018-19.

The information from this project is being combined with six other LTIM Project Selected Areas within the Basin. This will provide a Basin-scale evaluation (led by the Murray-Darling Freshwater Research Centre) of the contribution of Commonwealth water for the environment to the environmental objectives of the Basin Plan.

In addition to assisting the Commonwealth Environmental Water Office to demonstrate environmental outcomes, the LTIM Project promotes adaptive management of the water holdings. Identified outcomes and limitations are used to inform environmental watering in future years leveraging the best available, contemporary scientific knowledge.

Further information