Annual environmental water priorities in the Murrumbidgee catchment 2022–23

The Murrumbidgee catchment covers 81,527 square kilometres and includes 26 storage or diversion structures, 1,690 kilometres of the river, and the surrounding wetlands. The climate conditions range from alpine in the Snowy Mountains to semi-arid on the Riverina plains.

Wetlands throughout the Murrumbidgee support threatened species listed under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 and NSW Biodiversity Conservation Act 2016.

The Traditional Owners of the Murrumbidgee are the Barapa Barapa, Mutthi Mutthi, Nari Nari, Ngarigo, Ngunnawal, Nyeri Nyeri, Wadi Wadi, Wolgalu, Wamba Wamba, Weki Weki and Wiradjuri Nations.

Water for rivers and wetlands

During 2021–22, the Department of Climate Change, Energy, the Environment and Water (the department) worked with the Commonwealth Environmental Water Holder to capitalise on wet conditions across the catchment to deliver water for the environment to sites including the Gayini Wetlands and instream Murrumbidgee River and Yanco Creek. Water was also used to benefit wetland habitats in the Murrumbidgee and Coleambally irrigation areas as well as the North Redbank wetlands, Forest Creek and Wanganella Swamp.

In 2022–23 managed watering events will initially focus on maintaining permanent water habitat for southern bell frogs, native fish, waterbirds and other aquatic species.

Water managers plan to supplement existing system flows to provide the maximum benefit to plants and animals. Watering events will aim to restore a more natural flow pattern to support a robust food web and other system functions. Water managers will ensure essential connections between the river and floodplain wetlands to aid in the movement of essential nutrients and native fish.

Weather and water forecast

The El Niño–Southern Oscillation (ENSO¹) outlook remains at La Nina, with a return to neutral ENSO during winter. The Bureau of Meteorology issued an outlook in April 2022 which forecasts above median rainfall for May to July 2022 for eastern mainland Australia, with the chance of exceeding median rainfall stated as greater than 80%.

Indicative starting allocations are 95% for high security and 35% for general security licences. Water management plans reflect these wetter conditions and are mindful of the favourable starting allocations and high carryover.

Water managers have prepared watering plans that consider a range of weather and water availability scenarios in case it rains more or less than expected. This is known as resource availability scenario planning. ‘Moderate to wet’ conditions are forecast for the Murrumbidgee catchment in 2022–23.

_{1. ENSO: The interaction between the sea surface and atmosphere over the Pacific Ocean which results in dryer or wetter conditions (El Nino or La Nina).}

Resource availability scenario

Key planned actions for 2022–23

Waterbirds

Water managers have planned flows up to 200 gigalitres (GL) to provide foraging and breeding habitat for waterbirds, turtles, frogs and other aquatic species in core areas of Yanga National Park, Gayini and the North Redbank wetlands. Flows will water key Australasian bittern habitats in the Murrumbidgee and Coleambally irrigation areas and Yanco Creek systems.

Native fish

Water management plans allow for flows up to 100 GL to maintain instream and deep water off-stream habitats for native fish and to restore a more natural flow pattern to support native fish populations.

Vegetation

Water managers will provide 10 GL of water for the environment via pumping to key mid-Murrumbidgee and Yanco/Forest Creek sites currently out of reach of river flows, e.g. Willbriggie Lagoon, Wanganella Swamp and Rhyola Swamps.

Connectivity

Water managers have planned post airspace release and/or tributary event recession management flows up to 140 GL to inundate hundreds of mid-Murrumbidgee wetlands and the Lowbidgee lakes, while removing the effects of 3 weirs within the lower Murrumbidgee river channel and maximising fish passage (assuming reasonable starting allocations).