Over the last two hundred years, we have altered our rivers irreversibly. We have directed water away from rivers and built thousands of dams, weirs and pumps on them. We have turned their natural flow cycles upside down, sending lots of cold water through their channels in summer and cutting off winter floods.
For river inhabitants, it’s as if they have already experienced a hundred years of climate change.
The truth is, there’s little chance of Australian rivers returning to their original flows. We can however make sure that our rivers have the water they need to reach and maintain ecological health.
More than just water in rivers
An environmental flow regime is not simply the amount of water that flows through a river system. It’s the whole pattern of flows – from how long it lasts, to how frequently it flows and how large it is.
Environmental flows are vital to supporting the river’s ecological processes. High flows provide triggers for fish breeding and supply water for fish passage, so that they are able to move up and down rivers to appropriate habitat. They also keep estuaries open and provide recreational opportunities. Low flows in summer maintain fish refuges and connect habitats. Spring floods regenerate wetlands and floodplains and replenish the river channel.
Environmental flows also impact on the shape of our rivers and affect the condition of wildlife habitat. They enable pools and billabongs to be linked to channels. They flood wetlands and maintain their ecosystem function. Without environmental flows, water quality can suffer.
While environmental flows are vital for a healthy river environment, it’s important to remember two things:
- The environmental flow regimes recommended by scientists are usually the bare minimum the river needs to remain healthy. Optimum environmental flows are generally much higher and do not come under consideration.
- An environmental flow is only one part of a bigger picture. The total riverine environment, including riparian vegetation, instream habitat, salinity, water quality and other issues such as climate change, are important factors that impact on our rivers.
Our environment needed a voice
Our work in healthy rivers began with a recognition that the rivers in our state were under threat. We knew that someone needed to speak up for water for rivers. We became that voice. And we’re campaigning for formal flow entitlements for our rivers and streams.
Returning water to the environment – how should we do it?
Environmental Flows: Murray Darling, Murray Darling Basin Commission. Take me there