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North-west flows in early 2020

Fish, wetlands and riparian habitats

Rainfall and flow events improve the health of the environment. Learn more about fish, wetlands and riparian habitats.

Royal Spoonbill (Platalea regia) feeding over inland waters.
Golden Perch larvae and early juveniles fish samples
Figure 1. Golden Perch larvae and early juveniles collected at the northern end of Lake Wetherell in late March 2020 (left) and a drift net sample of numerous other fish species and aquatic animals (right). Image courtesy of NSW DPI Fisheries 2020.


Flows improve the connection of the river system so that deep pools are linked together. The Barwon-Darling River is again connected with its tributaries. Fish and other aquatic animals can move up and down significant lengths of the rivers. Iconic species like Murray Cod, Golden Perch and Silver Perch breed and disperse during these connecting flows. Flows like this help maintain healthy fish populations throughout the Northern Basin. View more information about fish and flows.

Researchers from the Department of Primary Industries (Fisheries) monitored fish populations and fish movement during the flow event. Monitoring will continue over the next year. Preliminary results indicate that Golden Perch had numerous breeding events because of these flows. Larvae and juveniles were found in the flowing waters from the Moonie River down the Barwon-Darling River and in Lake Wetherell (Figure 1). Finding Golden Perch juveniles and larvae at the Menindee Lakes is of great significance because the lakes are an important nursery for Golden Perch. It is known that fish that grow up in this nursery move throughout the Northern and Southern Basin in later years.

During the drought, water mixers were placed in ten large weir and refuge pools in the river at Menindee and in the Lower Darling River. These mixers protected some fish so that the population could recover when the river began to flow again. The mixers are no longer required as the water quality has improved because of these flows. View more information about the native fish drought response.

Fact sheet

To find out more about how native fish benefited from the flows read Native fish outcomes from the 2020 North-west flows.

Download the fact sheet (PDF. 434KB)

Wetlands and riparian habitats

Rainfall and flow events improve the health of the environment. Critical wetlands and riparian habitat wet or fill with water. During times of drought animals and vegetation can be sustained. Such events also help to start the recovery from drought.

Satellite imagery has been used to monitor flows. Inundation maps of the Gwydir Wetlands and Macquarie Marshes are being made for the rainfall events and indicate that parts of the Macquarie Marshes received flows from mid-February. By the end of April, more than 2600 ha of the critical Northern Reedbed was inundated.

Fact sheet

This fact sheet provides background information on drought recovery in the Macquarie Marshes. On April 5 2020, the department allowed supplementary access for water users in sections of the Lower Macquarie River system for a limited period of time.

Download the fact sheet (PDF. 919KB)

In the Gwydir Wetlands, flows began to reach the core reeds by the end of January. More of the wetlands were inundated during February and March. In the Central Gingham Water Management Area, more than 1700 ha of semi-permanent wetlands (Common Reed, Cumbungi, Water Couch) were inundated. In the Lower Gwydir, more than 1800 ha of semi-permanent wetland was inundated.