After recording the hottest 3-year period on record, the ecosystems of the southern Murray-Darling Basin (sMDB) were in desperate need of reprieve. The drought-breaking rainfalls which have occurred in 2020 and 2021 are helping kickstart the recovery of essential wetlands, floodplains, and freshwater-dependent threatened species. In addition, heavy rainfall during the end of last year helped provide unregulated flow events to most southern catchments of the sMDB, with the Goulburn, Ovens, and Kiewa receiving particularly high inflows. The recent heavy rainfalls of winter and spring have provided additional natural flow pulses to the rivers of the sMDB, with environmental water being added to help increase the size and duration of these naturally occurring flow events.
These high inflows across the Basin have led to huge environmental benefits for the ecosystems which depend on them. The Menindee Lakes, which support freshwater ecosystems of the lower Darling and lower Murray, have received higher inflows from late 2020 and have now filled for the first time in 5 years. Due to available water, environmental watering was delivered to the lower Darling over 2020-21 and helped significantly increase recruitment and establishment in Murray Cod and Golden Perch populations. Similarly, water availability allowed for environmental water delivery to the floodplains of the lower Murrumbidgee, which supported the largest waterbird breeding event recorded in the Basin in 2020-21 and was the largest breeding event to be initiated and maintained purely from environmental water allocations.
Spring 2021 has seen continued high inflows and subsequent environmental watering benefits. During the past month, water gauges along the Murray, Goulburn and Broken rivers have recorded the highest daily inflows since 2016. While with the Menindee Lakes now full, water has been released down the Darling-Anabranch for the first time since 2017. The anabranch watering will run south to meet the Murray near Wentworth and will support threatened fish species and ecosystem connectivity while supporting local graziers.
The Murray Darling Basin Balanced Water Fund (BWF) has also taken advantage of the increased opportunities to top up natural flows with environmental watering events. For example, Lake Henry and Little Frenchman’s Creek were recipients of sizable environmental water donations in 2020-21, which led to increased numbers of Southern Bell Frog being detected. Both sites are planned recipients for environmental watering events in the coming year.
To date, BWF has donated 4,600ML of water and is looking to make its largest environmental water donation, amounting to almost 4,000 ML in FY2022. Table 1 below shows the impact the funds were able to support since its inception in 2015.
|BWF Donation to June 2021 since inception|
|Volume Donated by BWF||4,600 ML|
|Leveraged Contribution – CEWO & NSW DPIE||3,900 ML|
|Number of watering events||27|
|Number of wetlands watered||31|
|Area of wetlands directly inundated||630 Ha|
|Estimated area for improved biodiversity outcomes||6,000 Ha|
|Number of threatened species supported||16|
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