The figures are in, and the Commonwealth Environmental Water Holder (CEWH) delivered the second highest amount of water for the environment on record, in 2023-24.
The CEWH, Dr Simon Banks, said around 1800 gigalitres of commonwealth water for the environment had been used to maintain or improve conditions in river and wetland systems across the Murray-Darling Basin.
"To put that in perspective, that's around 720,000 Olympic swimming pools or 3.6 times the volume of Sydney Harbour," Dr Banks said.
"It's second only to the 2021-22 water year which saw 2016 gigalitres of environmental water used.
"Last year we were able to deliver such high volumes thanks to high allocations due to previous wet conditions, as well as strong collaborations with our partners.
"We work closely with state agencies, landowners, First Nations people, communities and industry to get water where it's needed at the right times and have teams of dedicated scientists monitoring to ensure we know if any improvements can be made and what outcomes our water is achieving."
Dr Banks said another record had been broken with the volume of environmental water flows that had crossed the South Australian border.
"For the first time, more than 1000 gigalitres headed to South Australia which was partly made up from return flows from upstream use, meaning we could multiply the benefits from the same parcel of water," he said.
"It's essential to acknowledge the outcomes we achieved from our environmental watering activities, noting the importance of the Murray-Darling Basin as a place that's home to 2.4 million people and encompasses unique habitats that are critical to the survival of plants, animals, people and the whole river system.
"One of the wins was in the Goulburn River through what we call a 'winter fresh' to remind platypuses to build their nests nice and high on riverbanks to keep their eggs and young from drowning if the river rises later in the year.
"This water also increased the habitat available for native fish and water bugs by inundating connected anabranches and wetlands.
"As the water flowed out of the Goulburn River it then benefited the Murray River downstream by improving water quality and helping to break up blue-green algae, coinciding with a delivery of water for the environment from the lower Darling/Baaka."
Dr Banks said environmental flows in the Murrumbidgee had supported endangered Australasian bitterns to breed.
"Monitoring of the elusive bitterns through our science program, Flow-MER, confirmed that when water for the environment was delivered, the number of male bitterns calling for a mate to breed with more than doubled - a great outcome."
Other highlights of the 2023-24 water year include:
- More than 41 gigalitres of environmental water, mainly Commonwealth water, was protected through the Barwon-Darling to reach the Menindee Lakes. This protected water was then passed through Menindee Lakes as a part of an innovative trial, which meant it could travel further downstream into the lower Darling/Baaka River and the River Murray and achieve more environmental outcomes.
Water for the environment was also used:
- in the Gwydir, Namoi and Macquarie valleys to increase connectivity of rivers to the Barwon-Darling river system, improving water quality and opportunities for native fish to disperse
- in the mid-Macquarie, Namoi, Peel and Gwydir rivers to support native fish breeding and movement, particularly in spring. The flows were specifically designed to support key species such as the threatened Murray cod and freshwater catfish
- to inundate wetlands in the Macquarie Marshes, the Gwydir Wetlands, and the Western Floodplain at Toorale. This improved the growth and condition of vegetation at these sites, and supported ecosystem function, and frog breeding. It also provided food and habitat for waterbirds, fish, frogs and turtles. Several waterbird species benefited from the flows, including brolga, Latham's snipe and sharp-tailed sandpiper
- to support the successful completion of one of the biggest pelican breeding events ever at Lake Brewster. The largest colony counted had 49,500 nests between September 2022 to March 2023. Water for the environment was used in 2023 to maintain water levels and water quality to ensure the pelicans could finish their breeding
- in the Lachlan River to stabilise water levels during the Murray cod nesting period to support their nesting and dispersal
- at Gayini Nimmie-Caira to help maintain native fish populations by protecting and improving the condition of fish habitat and providing opportunities for movement. It also maintained foraging habitat for remaining juvenile birds
- in the Coorong, environmental water was used to maintain flows to flush salt out of the River Murray system and support critical lifecycles of species that use the internationally significant Coorong and Lower Lakes. Water for the environment plays a vital role in maintaining a baseline level of condition in the Coorong, including helping to manage acceptable salinity levels, during dry periods that allows it to bounce back once conditions improve
- to encourage golden perch to move and spawn in the lower Goulburn River. This encouraged golden perch spawning and migration and provided food sources, such as water bugs, for native fish and platypus. Initial results from monitoring of the late spring fresh through our science program, Flow-MER, show that fish breeding has occurred.
Dr Banks said environmental watering actions in this current water year would make the most of the positive environmental outcomes already achieved.
