Flow

A look at the flow and management at key locations

There is an uncontrolled inflow from high flows on the Darling River and a controlled inflow from Lake Cawndilla that feeds into the Darling Anabranch at Redbank Creek. The Darling Anabranch has only flown naturally three times in the last decade, in 2010/11, 2012 and 2021. Releases from Lake Cawndilla in 2013 and 2017 provided the other two recent flow events.

From 1890 to 1961 water flowed the full length of the Darling Anabranch to the River Murray nine times.

From 1962 to 2008, there was an annual regulated release into the system that is no longer applicable with the new water pipeline for landowners along the system.

To complicate matters, there is a series of 16 lakes along the Darling Anabranch that range from 120 to 11,000 ha in size. Water can be diverted into the lakes making it difficult to forecast the flow along the system. For example, in 2022, the high flows from both the Lakes and the Darling itself were mainly being diverted into the lakes. An uncontrolled flow into Popio Lake was still taking approximately two thirds of the remaining flow from the system as I paddled past. This is more likely to occur after the initial peak flows down the system as they try to minimise the impacts of prolonged flooding to the river banks. You should be able to see the lakes fill from the National Maps DEA Surface Reflectance (Sentinel-2 Near Real-Time). This will give you some idea of what is happening in the middle section of the anabranch before the gauge at Dam 183.

As a general rule, most high flow events in the lower Darling are caused by winter rainfall in central and northeastern NSW that arrive in late winter and spring, while it is the summer monsoon rainfall in southern Queensland that arrive in autumn.

Some key observations of some recent flow events are noted below:

Darling Anabranch Offtake rarely flows. The Darling needs to be above the 6 m mark before water naturally splits over the banks.

The following two images show a rising Darling river and the start of the flow into the Darling Anabranch at around the 6 m mark.

2011 saw a high flow from both the Lakes and the Darling. The resulting flow pattern was irregular until the high flows were seen a number of months after the water release started.

2017 saw a controlled release from Lake Cawndilla, no flow from the Darling River.

2021 saw a small controlled release from the lakes, followed by a high flow from the Darling.

Gauge Distances

0 km Lake Cawndilla

42 km Redbank Ck (+42 km)

66 km Offtake (+24 km)

116 km Wycot (+50 km)

298 km Dam 183 Downstream (+182 km)

385 km Bulpunga (+87 km)

440 km Tara Down (+55 km)

516 km Murray River (+76 km)

While smaller than the other flows, the 2017 event seems to be the best indicator of the time it takes for water to flow through the system. It appears to be rather slow at around 8 km per day so don't expect much paddling assistance and nearly two months if you are following a flow peak. With that in mind, you will likely want to see a good flow event to push water down the system for a number of weeks before starting out, along with a consistent flow at both Wycot and Dam 183 (Old Broken Hill Crossing) to ensure water is not being lost into the lower lakes.

This was not backed up with rainfall or local observations that could change how fast the water flows through the system and how much is lost filling lakes along the way!

My personal opinion on the flow requirements

I paddled Cawndilla Channel, Tandou Creek, Redbank Creek and the upper section of the Anabranch on around 1,000 ML/day. This provided great paddling conditions, but there were a few spots where a lower flow could become problematic, namely upper Tandou Creek, and the snaggy and tree-filled sections of the other areas. It is difficult to estimate the point where paddling around the thickets of trees will become unnavigable. Similar thickets on the lower anabranch were navigated with a lower flow.

Due to an uncontrolled redirection of water into Popio Lake, I mostly paddled the lower section at 300 ML/day. The conditions with this flow were generally easier than in the top section due to cleaner pools and channels. At this height I ran three channelled flowing sections and a number of wider flowing or pool sections that were shallow, but I only grounded the kayak a small number of times. I wouldn't be alarmed to paddle here in a slightly lower flow but due to the groundings I would recommend a slightly higher flow, somewhere between 400 ML/day and 500 ML/day.