Why building more big dams is a costly gamble for our future water security and the environment

Climate change and biodiversity loss are mounting threats to Australia’s water security. So we often hear calls for more dams. But is that the answer?

Our recent research reveals large dam projects are costly gambles with public money. They often fail to deliver promised economic benefits. They also have major environmental, financial and social impacts.

In New South Wales, some members of the Lower Lachlan River community were concerned about plans to expand Wyangala Dam. They first asked us in 2020 to investigate its full costs and benefits, with findings presented at a local workshop in 2022.

The first WaterNSW estimate of capital and operating costs was A$620 million in 2018. Within a few years, it had soared to as much as $2.1 billion. In 2023, the project was scrapped because it wasn’t economically viable...