The Blue Heart

Stand on the low Maroochy floodplain and read what a century of confidence made of it: dead-straight channels running off flat cane paddocks, levee banks holding the river out, and grass where a wetland used to breathe. It sits at the very bottom of the coast’s gradient, the ground the whole reef-to-range slope drains into, and for a hundred years it was read as a single problem to be solved by getting the water off it as fast as possible. Dig the channels, throw up the levees, drop the water table, turn swamp into cane on the nineteenth-century certainty that a drained swamp was an improved one. The Blue Heart runs that logic backwards, deliberately and at great cost.

Across more than five thousand hectares, a serious slice of the floodplain, a partnership of Sunshine Coast Council, the Queensland Government, the water utility Unitywater and the Kabi Kabi Peoples Aboriginal Corporation is un-draining the country: opening the levees, blocking the drains, and letting the tide and the rain creep back onto land written off as farmland generations ago.

Strikingly little of the rebuilding falls to human hands. A wetland does not have to be assembled. Let the water back and it re-sorts itself by the variable that ruled it all along, how far the salt reaches. Where the tide runs in freely, grey mangrove and then saltmarsh return to the lowest, saltiest ground. Behind the tidal reach, where rain and groundwater pool but the sea seldom comes, freshwater reed, sedge and paperbark reassemble. It is the same banding any undisturbed estuary falls into. The restorers’ job is the water. Yandina Creek, just upstream, shows it: old cane paddocks, sold off when the local mill closed, turned themselves back into a wetland thick with birds the moment their ageing floodgates failed and the river crept in. The country did the work, a birdwatcher noticed, and what began as an accident now anchors the larger project as its proof of concept.

Why spend so much to re-flood land that earlier generations spent so much to drain? Because the accounting has changed. A working wetland does an enormous amount of unpaid labour, and none of it ever came with an invoice, which is why it was drained. Price the labour and the case turns overwhelming. It soaks up floods that would otherwise reach houses, storing the surge and releasing it slowly, the flood mitigation a drain merely shunts downstream and makes worse. It filters the run-off before it reaches the bay. It nurses the fish and prawns the estuary fishery is built on, hiding the young among mangrove root and seagrass. And it banks carbon in its airless, waterlogged mud, the “blue carbon” of the tidal wetlands, gram for gram among the densest stores on Earth.

A fourth dividend belongs to this floodplain in particular, and it is the quiet one. Iron sulfides riddle the buried muds of the Maroochy: harmless while they stay wet, a chemical landmine if they dry. Drain them, let the air in, and they turn to sulfuric acid that the next big rain flushes into the creeks in a slug strong enough to strip the protective slime from a fish’s skin. The red-spot ulcers on the bream and flathead around Bli Bli tend to follow these pulses. Keeping the ground wet keeps that hazard drowned. The Blue Heart rebuilds a wetland and, in the same act, holds a poison down.

None of this is a fantasy of returning the floodplain to some untouched past. The country is being managed back toward function, band by band, on the principle this coast keeps rediscovering: restore the conditions the wetland needs, and let it do the rebuilding. We spent a century and a fortune taking the water off this land. That a project on this scale now pays to put it back is measure enough of how far the reading of this country has turned.