A year in the Murrumbidgee catchment: 2020–21

This bar chart and table provide a summary of 493,768 megalitres of water for the environment delivered in the Murrumbidgee catchment during the 2020–21 watering year. Volumes are indicative only. Watering event numbers in the bar chart and table relate to location numbers marked on the map.

Watering event number	Location	Outcomes	Start date	Finish date
		1			Yanga National Park		06 Jul 2020	25 Feb 2021
2	North Redbank		10 Jul 2020	23 Dec 2020
3	Gayini (Nimmie-Caira) wetlands		27 Jul 2020	21 Feb 2021
4	Yanco and Forest creeks		20 Aug 2020	08 Feb 2021
5	Wanganella Swamp and Middle Wetland pumping		10 Sep 2020	27 May 2021
6	Coleambally Irrigation Area – wetlands		15 Oct 2020	30 Mar 2021
7	Murrumbidgee Irrigation Area – wetlands		23 Oct 2020	21 Mar 2021
8	Lower Murrumbidgee pumping		26 Oct 2020	14 Dec 2020
9	Mid-Murrumbidgee wetlands pumping		30 Oct 2020	30 Apr 2021
10	Western Lakes (Paika)		01 Apr 2021	17 Jun 2021
11	Native fish pulses		09 Nov 2020 06 May 2021	20 Nov 2020 25 May 2021

Notes: NSW = NSW licensed environmental water; CEW = Commonwealth licensed environmental water; EWA = Environmental water allowance accrued under the Water Sharing Plan for the Murrumbidgee Regulated River Water Source 2016.

In partnership with the Murrumbidgee Environmental Water Advisory Group, the Commonwealth Environmental Water Holder and landholders, environmental water managers from the Department of Planning, Industry and Environment delivered much of the available water for the environment to the Lowbidgee Floodplain, primarily to wetland systems in Gayini (Nimmie-Caira), North Redbank and Yanga National Park.

This water:

• triggered southern bell frog population expansions and recruitment across all inundated wetlands
• initiated and maintained large ibis, egret, heron, spoonbill, darter and cormorant rookeries in the Gayini and Yanga wetlands
• provided refuge and breeding opportunities for Australasian bitterns at numerous wetlands including, Gayini, Yanga, Campbells Swamp, Mainie Swamp and McCaughey’s Lagoon.

Water for the environment was pumped into Sunshower Lagoon near Darlington Point by a local contractor. Pumping eliminated carp, maximising the aquatic vegetation and frog response, with southern bell frogs calling at the site for the second time in a decade.

Creek flows to Wanganella swamp on the forest creek system were supplemented with water for the environment using a neighbouring landholder’s pump. This action continued the rehabilitation of this important waterbird breeding site, with 72 water-dependant bird species recorded, 37 of which were confirmed to be breeding.

These outcomes were achieved through implementing the key planned actions proposed for the 2020–21 water year.

Supporting colonial waterbird breeding in the Lowbidgee Wetlands

The Lowbidgee Wetlands are one of the most important colonial waterbird breeding areas in the Murray–Darling Basin. The Lowbidgee wetland systems often support nesting waterbird colonies in the tens of thousands. Nesting typically follows significant overbank flooding events. These breeding events have often been sustained with the application of water for the environment.

The 2020–21 season reset our understanding around the scale of waterbird breeding that can be initiated and sustained solely with the use of water for the environment.

Inundations of Yanga National Park, Gayini wetlands and the North Redbank wetland systems with water for the environment began in winter 2020.

Abundant foraging areas provided ideal conditions for waterbird rookeries to establish across 20 different sites. The largest site located within Yanga National Park contained an estimated 2600 nests, dominated by egrets, cormorants and herons.

Australasian bitterns and Australian little bitterns also bred in the abundant tall spike-rush swamp habitats of Yanga National Park.

To the east of Yanga in the Gayini wetland system, the Eulimbah Swamp rookery contained an estimated 18,600 nests, primarily straw necked ibis, glossy ibis and spoonbills.

This scale of nesting was the largest ever documented in the Murray–Darling Basin, where water for the environment alone has firstly initiated and then sustained a successful breeding event.

By the time all the waterbirds had fledged and water levels were allowed to decline, over 40,000 hectares of wetlands had been inundated using just under 400,000 megalitres of water for the environment.

Water for the event was provided by the Department of Planning, Industry and Environment (the Department) and the Commonwealth Environmental Water Holder.

The environmental water delivery in Gayini was managed by the landowners the Nari Nari Tribal council in close consultation with Department staff and with the oversight of a multi-agency technical advisory group.