The failure of the Murray Darling Basin Plan

The Murray Darling Basin Plan (MDBP) was established in 2012 in response to the Millennium Drought (1997–2010), which certain people believed was proof of climate change. In their view it would never rain heavily again, leaving the environment permanently short of water.

The issue gained particular currency in South Australia, where it was also claimed Adelaide's water supply was at risk.

As wiser heads knew, and time has proved, the Millenium Drought was not unique and certainly not an indicator of the future. It was simply Australia being Australia, with its droughts and flooding rains.

Nonetheless, it resulted in a plan to send vast amounts of water down various rivers, most of it ending up in the Murray, supposedly to benefit the environment, keep the mouth of the Murray open, and to guarantee water for Adelaide.

The Plan called for the 'return' of 2,750 GL of water to the environment plus an additional 450 GL under certain conditions (now mostly achieved). This water came from farmers and rural communities in Queensland, NSW and Victoria, some through efficiency measures but mostly by buying water rights from farmers. That was water that would otherwise would have been used to irrigate crops.

These numbers were never science-based. They were back of the envelope calculations negotiated by politicians based on political considerations. There are a lot of votes to be won by saving the environment, even when it doesn't need saving.

In South Australia there were six marginal seats for which both sides of politics were competing on the basis of offering the most water. The additional 450 GL was only added at the last minute in order to get the South Australians to agree to the Plan.

Under the Plan, of the 2,750 GL, SA is guaranteed a minimum of 1,850 GL a year. Delivering that much water means the Murray is now abnormally full all year round.

It was an absurd figure. According to the SA EPA, the state's total water consumption is just 1,000 GL per year, of which agriculture consumes three-quarters. Households, manufacturing and mining account for the remainder.

Adelaide also has a $1.8bn desalination plant capable of producing half its household and industry requirements. The plant is obliged to use renewable energy though, which means it is expensive and rarely operates.

With so much water being sent across the border, a large proportion of it ends up in the so-called lower lakes, Lake Alexandrina and Lake Albert.

Until the 1930s these lakes were open to the sea, in common with every other river estuary in Australia. But then five barrages were erected which substantially changed the natural environment.