Environment

Great Barrier Reef sediment flow reduced by 97 per cent at test site

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A north Queensland test site has reduced the amount of sediment flowing into the Great Barrier Reef by 97 per cent, Greening Australia has revealed.

The 1.5-hectare site forms part of the Burdekin River catchment, south of Townsville, which has been identified as the highest sediment-producing river catchment impacting the Great Barrier Reef.

Strathalbyn cattle property owner Bristow Hughes with Greening Australia chief executive Brendan Foran in the restored 1.5 hectare pilot area.

Photo: Annette Ruzicka

Ten million tonnes of sediment flow down Queensland river catchments and settle across the Reef each year.

Virgin's Sir Richard Branson came to Australia in March 2016 and committed $100 million over three years to begin Greening Australia's Reef Aid bid to reduce sediment erosion by 70 per cent.

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This week at Strathalbyn, a privately owned cattle property about three hours south of Townsville, Greening Australia's gully remediation expert Damon Telfer said results showed they could reduce sediment at the site by 97 per cent.

Mr Telfer said sediment suspended in the water flowing through a “control eroded gully” at Strathalbyn, with no modification, was “between 60 and 180 grams of sediment per litre”. At another unmodified gully, the suspended solids was 400 grams per litre.

In areas where the erosion had been repaired, Mr Telfer said the results were stunning.

“The figures we are getting out of this one (the repaired gully) are that the material coming out is in the order of 0.01 grams to 0.02 grams per litre suspended sediment, so it is a dramatic result,” he said.

Greening Australia's Damon Telfer oversees construction works to repair tunnel-erosion at Strathalbyn behind Townsville.

Photo: Tony Moore

The soil at Strathalbyn is fine-grained sodic soil, which is a high erosion risk as it does not bind well.

As part of its scheme, Greening Australia bulldozes the entrenched, tunnel-eroded soil, then battens and revegetates the soil to completely recreate the original landlines at Strathalbyn.

It plans to repair 15 hectares of eroded Strathalbyn soil in 2018, a tenfold increase on 2017, and wants to raise $132 million to rehabilitate 2000 hectares at about 35 different locations by 2030.

Australian Institute of Marine Science marine biologist Ken Anthony said the erosion project should be scaled up quickly, because the impact of climate change "would begin to bite by 2030".

"It's a closing opportunity, but if we take it, we can change history," Dr Anthony said.

Since 1945, gullies on the property have leached an average 956 tonnes per hectare every year into the Burdekin River, equating to more than 550,000 tonnes of fine silt.

Sediment flowing down the Burdekin River towards Upstart Bay near Bowen.

Photo: Tony Moore

More than 65 per cent of the fine silt from Strathalbyn and 47 per cent of the sediment from the overall Burdekin River basin gets to the Great Barrier Reef.

Queenslands Department of Environment and Science is a partner in the Reef Aid project, matching “dollar to dollar” funds from private donors – aside from the initiaul $100 million contribution from Sir Richard – and contributing $2 million over four years to the erosion control project.

A spokesman for Environment Minister Leanne Enoch said the initial results were encouraging.

The department was cautiously optimistic, but cautioned the erosion measures had only been through one wet season.

“They do not indicate monitored results over multiple seasons and years,” Ms Enoch's spokesman said.

“It would be premature to assess on these results alone, even though they could be expected to continue if the area continues to be well managed.”

Greening Australia ecologist Lynise Wearne at the Strathalbyn site outside Townsville.

Photo: Annette Ruzicta

Mr Telfer said Greening Australia was deeply committed to the Reef Aid erosion project.

“We dont want to just make it look pretty on the surface, come back in five years and find the whole thing has just gone off again,” he said.

Greening Australia chief executive Brendan Foran said ecologists had known of Great Barrier Reef problems caused by sediment and nutrient run-off for 30 years.

“Yet when we started here two years ago, people would say you cant just go off and fix gullies,” he said.

“I think we have shown with this pilot here that you can and that you can significant effect water quality.”

Mr Foran said improving water quality is acknowledged by reef experts as the second-highest priority in preserving the Reef.

“By 2030 we can do 2000 hectares of gullies that look like this and they are the shittiest, biggest sediment-producing gullies in the reef catchment,” he said.

Ureisha and Bristow Hughes, with their children, Brialie and Archie

Photo: Tony Moore

Bristow and Ureisha Hughes run 5000 to 6000 head of cattle on their Strathalbyn cattle property.

They allow Greening Australia to work on their 34,000-hectare property, where 64 hectares is badly eroded.

Greening Australia will rehabilitate the 64 hectares of badly eroded soil on their cattle property, which will cut erosion, but not allow him to run more cattle.

"That is why it is so hard for a farmer to get in and fix this because it costs so much to do with very little – or no gain from doing it," he said.

"We really do want to look after the environment, but when you have to spend $500,000 to fix a hectare, we simply cannot afford to do it."

The reporter travelled to Strathalbyn as a guest of Greening Australia.

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Tony Moore

Tony Moore is a senior reporter at the Brisbane Times

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