The Menindee Lakes is a system of 9 large, but relatively shallow lakes, located in south-west New South Wales on the Darling (Barka) River, about 200 kilometres (120 mi) upstream of the Darling River's junction with the Murray River. The Darling River is fed by nine major tributary river systems flowing from south-east Queensland and north and central NSW. The town of Menindee is close to the lakes and Sunset Strip township is on the northern shore of Lake Menindee. The nearest city is Broken Hill.

There are 4 main lakes in the system:

The lakes rely on replenishment, when water flows over the banks of the Darling (Barka) River. The NSW Government modified the lakes (completed 1968) to improve their storage capacity for farming, recreation, mining and urban water supply and to help manage floods in the Darling River. In the 1960s, governments decided to use some of the lakes as water storages, building a large weir (Main Weir) to divert water into lakes Pamamaroo, Tandure and Bijijie. Levees, block dams and channels were built to regulate the flow of water in the system. There is relatively little information on the flooding regimes of the lakes before they were regulated (dammed) in the 1960s but they were undoubtedly highly productive and important wetland systems where many fish were spawned.

The Menindee Lakes Water Storage Scheme supplies water to Broken Hill, the lower Darling and to water users along the Murray River in New South Wales, Victoria and South Australia under the Murray-Darling Basin Agreement. Seven of the lakes have been incorporated in an artificially regulated overflow system providing both for flood mitigation and as storage for domestic use, livestock and irrigation downstream. The lakes are also important for waterbirds.

Recent research (Thoms and Delong 2018) found that the food webs have changed in a way that suggests that the ecological resilience of the system has declined.

The lakes were filled to capacity in 2021 with Lakes Cawndilla and Lake Menindee filling completely in early September meaning that the system was filled to over 98 per cent capacity with water flowing into Lake Speculation for the first time since 2012.

The first people living around the Menindee Lakes area are known as the Barkindji or Paakantyi. The original inhabitants gained Native Title over the area in 2015, but it didn't include control of water use on the Darling (Barka) River. In January 2019, ABC News wrote the Chairperson of the Menindee Barkandji Elders Group, Patricia Doyle, called for better water management in the area. "The government needs to adopt a whole-system approach to water management in the Darling River," she said.[1]

There have been periods of mass fish deaths in the Lakes. Fish kill data from the NSW Fisheries Department shows the size of the sudden deaths, after 1960 to be much greater. Between December 2018 and January 2019, and again in late 2022 and early 2023, there were at least 5 mass fish deaths reported along a 40-km stretch of the Darling River, downstream of the Menindee Lakes. These are often described as the "Menindee Lakes fish kill". It is estimated at least a million fish died, most affected were bony herring, Murray cod, silver perch and golden perch. The Australian government report on the deaths determined three main causes: inadequate water flow in the Darling River, poor water quality and a sudden change in temperature.