It might be the biggest whodunnit — or what-dunnit — in Australia.

More than 2 trillion litres of water — enough to fill Sydney Harbour four and a half times — has gone missing from our largest and most precious river system — the Murray-Darling Basin.

And it’s happened in what was already one of the driest periods the basin has seen.

According to an investigation by some of Australia’s top water scientists, shared exclusively with the ABC, 20 per cent of the water expected to flow down the rivers from 2012-2019 was simply not there. That’s despite almost $7 billion being spent to protect the health of the system’s rivers and ecosystems that rely on them.

Was it stolen? Was it lost? Has climate change made it go up in steam? Or was it simply never there in the first place?

There are clues scattered up and down the rivers but one simple message is clear in the scientists’ findings. For the first time, they provide evidence that the Murray-Darling Basin Plan — the most expensive environmental program in Australia’s history — is delivering much less water than was expected.

And the implications could be huge.

Read the full article on the ABC News website, featuring commentary by Prof Jamie Pittock