Plan to save Great Barrier Reef from encroaching farm pollution

The sky above is grey and drizzly, but the wetlands are still beautiful to behold. Flocks of magpie geese settle on the glassy water, honking and nibbling at bright green tufts of sedge.

I’m at Mungalla Station, a cattle property in far north Queensland. Here, a large-scale conservation project is underway. Its aim: to help save the Great Barrier Reef 20 kilometres away, out at sea.

The Great Barrier Reef is a World Heritage Site, and one that is known to be in dire trouble. The obvious threats are climate change and coral bleaching, both of which could kill swathes of the corals. But another major problem is agricultural run-off. About 10 million tonnes of sludge from farms wash onto the reef each year, smothering the coral, says Mungalla’s director Jacob Cassady.

Cassady is a member of the local Nywaigi people, who took over Mungalla when it was returned to them by the Indigenous Land Corporation in 1999. At that time, the property had been damaged by more than a century of cattle farming. Overgrazing had caused soil erosion, native vegetation had been cleared, and the wetlands along the coast were choked with invasive weeds.

This presented a big threat to the Great Barrier Reef. Sediments, pesticides and fertilisers were leaking into the wetlands and out to sea, poisoning and smothering reef organisms like coral, fish and turtles.

To restore Mungalla, the Nywaigi owners kept one section for cattle farming and allowed the rest to grow wild. Much of the area is now thickly forested and full of squawking bird life.

Since 2013, the owners have focused on restoring the wetlands. They call them the “kidneys” of the Reef, because they help to filter out silt and chemicals before they spill into the ocean.

First, they wanted to get rid of alien weeds like marsh grass, water hyacinth and watermoss that blanketed the wetlands and had squeezed out native aquatic plants. Fortunately, there was a simple solution: they knocked down an earth wall that had been built in the 1940s to stop the tide from coming in. The introduced species could not handle the saltiness of the incoming seawater and withered en masse.

Now, only a few small patches of these weeds remain. In their place, native sedges like the green grass-like bulkuru (Eleocharis spiralis) have sprung up, attracting geese and other birds that feed on them.

Water quality has also improved. Previously, microbes feeding on rotting weeds sucked oxygen out of the water, making it uninhabitable for wildlife. Now, Cassady says, the wetlands are filling up once again with fish and crocodiles. I back away quickly from the water’s edge.

The newly thriving wetlands will provide a buffer for the Great Barrier Reef, says Niall Connolly from Greening Australia, a conservation group that is helping with the restoration efforts. Silt and farm chemicals stick to the bulkuru and are buried underground via their root system, he says.

Greening Australia is now working with other landowners in the area to patch up eroded soil and rehabilitate 200 hectares of coastal wetlands. Their modelling suggests these relatively simple and cost-effective measures could cut sediment pollution by 75 per cent in key areas. This would go a long way towards meeting the Australian government’s target of halving sediment load in the Great Barrier Reef by 2025.

As we stare out at the geese flapping around the bulkuru, Cassady says the results have been even better than he expected. “I am elated,” he says. “You can feel the country healing itself.”

Greening Australia flew Alice to Mungalla Station