Murray-Darling irrigators
Dead fish in the Darling River system (Image: (Supplied/Kate McBride)

You’d be hard-pressed to find a better metaphor for the body politic than the Murray-Darling river system. Lying at the centre of the country’s fertile and arable east -- yes, I’m straining to remember Year 8 geography here -- the system’s two major rivers mimic the layout of the aorta and veins in the human body. It’s like a hint from nature: this is a one-time thing. Mess this up, and your country is screwed.

We made a good start on exactly that through the 20th century. With no real governance of the system as a unit, we regarded it as an unlimited intangible from which infinite amounts of water could be removed. For decades, individual farming was too small to really screw it up -- though by farming rice and cotton on a dry continent, we gave it a red hot go. Then, with the coming of large-scale agribusiness, things quickly went awry leading to the 1991 explosion of blue-green algae in the Darling. It was part of a series of localised environmental crises around the world in the years 1989-1991, perhaps the first on-the-six-o'clock-news indication that humanity had begun to have categorical impact on the global environmental system.