A year in the Barwon-Darling Barwaan-Baaka catchment: 2021–22

A total of 45,698 megalitres (ML) of water for the environment was protected in the Barwon–Darling Barwaan–Baaka catchment during the 2021–22 watering year using NSW licenses (1,943 ML) and Commonwealth Environmental Water Holder licences (43,755 ML). A further 3,296 ML of held environmental water from the Macquarie River was protected into the Barwon–Darling Barwaan–Baaka under active management. Figures are accurate at the date of publishing, but maybe adjusted.

Watering event number	Location	Outcomes
		1	Barwon–Darling Water Resource Plan Area

In 2021–22 environmental water managers worked with stakeholders and the community to protect water for the environment to support assets across the catchment such as native fish, riparian and wetland vegetation, and system connectivity.

Both NSW and Commonwealth environmental water licenses were used to protect water for the environment to support connectivity along the Barwon-Darling Barwaan–Baaka River. Licenses were used in the early part of the water year to protect 1,943 megalitres of NSW and 43,400 megalitres of Commonwealth water.

Protection under NSW licenses was primarily between Geera and Brewarrina. Commonwealth licenses primarily protected water in the reach between Bourke and Louth. Active management protected flows beyond the river reach to Menindee Lakes. Once the conditions in the catchment and its tributaries were wet, protection using NSW and Commonwealth licenses in the Barwon-Darling Barwaan–Baaka was no longer necessary to maintain flows. Conditions remained that way for the rest of the water year.

NSW and Commonwealth water for the environment contributed to meeting First Nations priorities instream, whereas natural flows inundated priority sites on the floodplain and backed up water into tributaries such as Yanda Creek.

Barwon-Darling floodplain gets a drink

In the summer of 2021–22 natural high flows from the northern tributaries combined to inundate the floodplains of the Barwon–Darling. These flows filled billabongs, anabranches, and wetlands. The event reached many areas that had not been inundated in 10 years. Flows peaked at more than 120,000 megalitres per day at Walgett with significant inflows from the Namoi catchment.

The event saw significant flows break out into Cato Creek near Brewarrina and the Talyawalka Channel near Wilcannia. This provided great benefits to the instream and riparian ecosystems of these areas before re-joining the system downstream and increasing instream productivity in the main channel.

The event provided a recovery opportunity for aquatic and floodplain flora and fauna. Floodplain wetlands and billabongs that received inundation will provide habitat for a number of frogs species to breed during spring, as well as foraging sites for waterbirds. Following the high summer flows, recruitment of flow pulse specialists, golden perch, and generalists, spangled perch, between Bourke and Louth was found in autumn fish surveys funded under the Flow-MER program.

Water quality monitoring by environmental water managers found areas of poor water quality at the front of the flow with low dissolved oxygen from the vast amount of organic matter collected from the floodplain. Despite these areas of low dissolved oxygen water, only 2 minor fish kills were recorded and the event overall had a substantial positive effect on the system that will be felt for years to come.