Water is a precious resource, so we work hard to get the most out of it for the environment.
We carefully plan and time flows so we can use it at many sites across the Murray–Darling Basin. Our goal is to reuse water for the environment as many times as possible.
What are return flows?
Return flows refer to water that has been used multiple times within a river system for various environmental purposes.
We might pump water to a site, like a wetland, to meet an environmental need. The water then continues to flow downstream to meet an environmental need at another site. This means water is returning back into the river system, helping meet a second, third and sometimes forth need before it meets the mouth of the system and flows out to sea.
Return flows are an efficient way to use water for the environment. They also keep the food chain healthy along the whole length of the Murray.
How we use return flows
When we deliver water for the environment to a wetland, only a small amount of water is used up. This water might be used through:
- evaporation
- vegetation uptake and animal activity
- seepage (like soil absorption).
The remaining water can flow back into the river system. This water can then be used again further downstream.
For example, a single flow in the southern Basin may:
- target wetlands in a river red gum forest
- flow downstream helping fish breed and move
- flow even further downstream to boost bird breeding.
Finally, the water would reach the Murray Mouth.
Southern Basin flows typically end up in the lower Murray, because water flows downhill.
This is both natural and important, as the entire Murray is a freshwater river system shared by people and nature.
Better understanding return flows
Almost 70% of the Commonwealth water for the environment we use in South Australia comes from return flows.
Despite this, some upstream communities think water is delivered directly to South Australia before pouring out to sea. They see water moving through the river channel, and believe it is only destined for South Australia.
Each Basin state has different reporting systems, which makes it hard to get information. The Basin Plan aims to make water data accessible to the public.