How science helps us make the most
of water for the environment

Written by Hilary and Irene from the Commonwealth Environmental Water Holder

How do we know if water for the environment is making a difference? It’s a question we, at the Commonwealth Environmental Water Holder are often asked. Our answer – the science tells us.

We use science to help us make decisions about how best to use water for the environment so that we can help keep our rivers, wetlands and floodplains, along with the plants and animals that depend upon them, healthy and thriving. What we learn from science helps us to make important decisions about why, if, how much, when, and in what pattern, water for the environment can be delivered.

Through programs like Flow-MER, science shows us how the quality, quantity and timing of water flows is vital for keeping the riverine and floodplain environments that we all value, alive, now and into the future. Essentially, science helps us to understand how our floodplains and wetlands function, as well as tracking whether we are making a difference with the water we deliver. This is why science is so critical – it helps us to work out how to use the water we have, to achieve the best possible results, for the environment and all Australians.

Ebony and Michele from the CEWH inspecting fish nets in the Lachlan. Photo: CEWH, 2020

As the amount of water we manage has grown, so has the amount of science monitoring, evaluation and research. Over the last 10 years, the Commonwealth Environmental Water Holder has invested in many different science projects that have helped to manage Commonwealth water holdings.

Our science projects have included short-term investigations that have lasted a few weeks, through to those running for a year or two, to long-term projects which span many years. We now have the Flow-MER Program, a three-year investment from 2019–2022. The Flow-MER Program builds on science we have previously undertaken, and continues to expand our water for the environment ‘knowledge bank’.

Thanks to the data collected and evaluated by these projects, we now have a better understanding of how to achieve specific outcomes with water for the environment. For example, we now know how much food baby birds need to grow, what it takes to get trees to flourish, where turtles trek to in dry times, how much fish food can be generated by small increases in river flow, and the importance of rivers as highways for fish movement.

Science is also helping us to use water for the environment to protect plants and animals from events like drought or hypoxic (low oxygen) blackwater events. We now know when a wetland has enough resilience to not need water, meaning we can allocate that water to an area that does need some extra help.

Each year we integrate the science with other information, such as how much water we have available, what the conditions are like for delivery, and how much water plants and animals need to support vital life cycle needs. We need this combined knowledge to squeeze the most benefits for the environment out of every drop of Commonwealth water. This is particularly important when water supply is low, and demand is high – a situation that we are increasingly facing in a drying climate.

Richard, our Local Engagement Officer in Mildura takes part in monitoring at Wallpolla Island. Photo: CEWH, 2019
Caption: Hilton Taylor (interim CEWH) and Local Engagement Officer Jason Wilson on Country. Credit: Commonwealth Environmental Water Holder.

The Northern Fish Flow

A great example of how science has helped us get the most out of water for the environment is during the Northern Fish Flow in early 2019. Flows for fish are important at every life-history stage, and water for the environment can be important for supporting breeding habitat, triggering spawning, encouraging migration, and producing fish food. In extended dry periods, like we saw in 2019 and early 2020, flows are important simply for survival.

In 2019, the Barwon River, one of the most important connecting rivers in the northern Murray–Darling Basin, hadn’t flowed for over 200 days. Waterholes were drying up, and the water that remained had poor water quality. We knew that if water quality reduced further, and the waterholes dried up, fish would die. Some of these fish are of conservation and cultural significance, like the Murray cod. Working together, the Commonwealth Environmental Water Holder and New South Wales Department of Planning, Industry and Environment, released water for the environment into the Barwon River to help fish survive in the waterholes until good rains returned. They also funded a monitoring project to track water quality in the waterholes before and during the flow.

The Northern Fish Flow in the Barwon River helped to support native fish stranded in waterholes. Photo: CEWH, 2019

What happened?

The results from this project showed that the delivery of water for the environment was successful in achieving its intended outcomes – improving water quality by keeping enough Dissolved oxygen in the water to keep fish alive until better times returned. This success means that we have learnt what worked and can consider similar actions in the future, in the Barwon River and other sites to help fish survive.

It is exciting to see findings from science projects showing water for the environment is making a positive difference to the environmental health of the Murray–Darling Basin. Every year we learn more about how we can use water to meet environmental needs. Environmental change takes time, and it will be many more years before the extent of benefits will be realised. While we can’t monitor everywhere, science is helping us to understand the key principles we need to follow to achieve beneficial outcomes.

It is great to be part of something that we know is making a difference to the birds, plants, animals, fish and people, who need our wetland and floodplains. As more projects are undertaken, we will continue to learn and adapt our management of the Commonwealth’s water holdings so that the river system is healthy, and can continue to benefit communities for many more years to come.

Alana from the CEWH takes notes during a fish survey in the Lower Lakes and Coorong. Photo: SARDI, 2019

Check out the latest updates from Flow-MER

We are working in partnership with scientists, water managers and communities across the Murray-Darling Basin to help us understand how fish, birds, vegetation and river connectivity are responding to Commonwealth environmental water. Read the latest stories to learn more about the work being done.

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