During the 2018–19 water year, water for the environment was released into the Gwydir Wetlands systems and Mallowa Creek watercourse. Water was also used to protect priority river reaches in the Carole Creek, Mehi and Gwydir rivers from complete drying. A small watering trial was conducted in Ballin Bora Creek, an anabranch of the Mehi River.
Gwydir Wetlands systems
A total of 60 gigalitres of water was delivered to the wetlands of the Lower Gwydir and Gingham watercourses. This watering aimed to preserve wetland condition in preparation for the forecast dry conditions. Almost 4000 hectares were inundated in the Gingham section and just over 3000 hectares in the Lower Gwydir section.
Surveys conducted in these areas reported:
- widespread growth of flow-dependent vegetation, including at sites not inundated for some time
- limited presence of the exotic lippia weed
- provision of habitat for many waterbird species during an extended dry period across the Murray–Darling Basin
- sightings of nationally endangered Australasian bitterns, 5 internationally recognised migratory bird species and 6 species listed in NSW Biodiversity Conservation Act 2016
- widespread recruitment of a range of flow-responsive frog species (from surveys in September and November 2018).
Four deliveries of water for the environment targeted pools in river reaches that had ceased to flow. Releases in:
- September 2018 provided water to pools in the Mehi River
- October 2018 targeted Carole Creek
- April 2019 supported the Mehi River and Carole Creek
- May 2019 benefited the Gwydir River.
The intent of these releases was to maintain water quality and water levels in pools. This would enable fish to move between pools and reduce the risk of fish kills from the drying river. No fish kills were reported in the Gwydir in 2018–19.
Mallowa Creek watercourse
Water delivery to the Mallowa Creek inundated about 2000 hectares of wetland and floodplain, enabling reconnection with the Moomin Creek.
Surveys of inundated areas found the water release:
- provided habitat for many waterbird species, with sightings of 3 internationally recognised migratory bird species and 4 species listed in NSW Biodiversity Conservation Act 2016
- positive responses from vegetation and key habitats
- benefited a range of frog species and supported widespread successful breeding outcomes, particularly for flow-responsive frog species.
Ballin Bora Creek watering trial
A trial watering of the Ballin Bora Creek via upstream private irrigation infrastructure was conducted from December 2018 to January 2019. Stock and domestic water was previously delivered this way, but this was the first-time managers of water for the environment worked with the landholder to deliver flows to the system to improve habitat in the stream. Water was delivered in two flows:
- A release of 388 megalitres, connected 28 kilometres of Ballin Bora Creek to the Mehi River, over 6 days.
- A delivery of 200 megalitres did not make the expected connection to the Mehi River, only reaching and filling ‘Coolibah’ crossing pool.
Delivery of water to Ballin Bora Creek topped-up waterholes, and supported water-dependent species including Latham’s snipe, turtles, several frog species and plants.
A flow was also delivered into the Mehi River to connect the Gwydir system with the Barwon River. More detail on this release is provided in the case study.