Rehabilitation of the Mary River after flood erosion is on track thanks to the community of Kenilworth

Twenty years ago, Brad Wedlock was desperate for the state of Queensland’s Mary River in Kenilworth, where each flood cut through thousands of cubic meters of farmland, releasing sediment to choke the southernmost part of the Great Barrier Reef.

Deforestation, sand and gravel extraction and the faulty practices of the past had turned what was once a shady, winding river into a barren waterway ravaged by erosion.

The pre-restoration river repair site at Kenilworth in April 2019.(Provided: MRCCC)

Fast forward to today and despite three floods this year, once eroded banks are strong and stable along a stretch of river being restored, thanks to the will of the community and the commitment of dozens of people.

“This site here looked terrible, there’s no two ways about it; it was a terrible, terrible site. There wasn’t a lot of habitat for aquatic species like the [endangered] Mary River cod,” Mr. Wedding said.

“It’s immensely different, the habitat values ​​are there, the site is progressing.”

A photo of rows of upright logs in a bare river paddock in 2019 compared to the same logs surrounded by plants in 2022.
Before (top, 2019) and now… the piles have stopped the erosion and the plantations are thriving.(Rural ABC: Jennifer Nichols)

The environment in play

The Mary River is the fourth largest contributor of fine sediment out of 35 catchments that flow into the Great Barrier Reef.

But as a project officer with the Mary River Catchment Coordinating Committee (MRCCC), Wedlock has witnessed the transformative power that community will, funding and careful planning can bring.

Earth-moving machinery is working to repair the eroded bank and put fields of piles.
The river repair site during restoration at Kenilworth in 2019.(Provided: Burnett Mary Regional Group)

In 2015, earth-moving machinery began to reshape eroded sand cliffs in sections of the Kenilworth riverbank, driving rows of 6-metre-long wooden piles which slowed the flow of flood waters.

ABC Rural last visited the project in 2019 and returning with Mr. Wedlock to see how the restoration project had coped with recent extremes in nature was uplifting.

A young tree with red leaves grows next to the pile field.
Fertile silt helps seedlings grow alongside the heap fields.(Rural ABC: Jennifer Nichols)

Although the trees have been hit by debris, their roots have remained firm and fertile silt is accumulating around the fields of woodpiles that will eventually rot.

Logs and sticks on the ground next to the trees.
Debris from the floods affected the plantations but most survived.(Rural ABC: Jennifer Nichols)

Habitat saved

A ribbon-like aquatic plant called vallisneria, vital to the prehistoric lungfish that swim in these waters, had survived the third highest flood on record.

“After the 2013 floods, they were all washed away, so the lungfish had no habitat to spawn,” Wedlock said.

“Seeing Vallisneria still there means we may have slowed the system down enough for it to hang on, whereas after 2013 it took three years for it to come back.

A green water weed photographed in the river.
Vallisneria, or ribbon plant, is vital habitat for lungfish and has survived flooding.(Rural ABC: Jennifer Nichols)

Over 45,000 native riparian seedlings have been planted along the banks of Kenilworth.

Ruth and Stephen Carter worked hard to help water hundreds at Ubi station at the height of the drought.

As the native plants grow, the pile fields disappear and the 10-meter cliffs threatening their land and their livestock are just an unpleasant memory.

A man and woman stand in front of a riverbank with growing trees and fields behind them.
Ruth and Stephen Carter are delighted with the progress of the remediation work.(Rural ABC: Jennifer Nichols)

“With each flood, beautiful soil kept falling into the river,” Ms Carter said.

“We lost a good 10 acres [four hectares] in forty years, so that [project] certainly protected him beyond any dreams we’ve ever had.”

Seven sites have been remediated in Kenilworth with the help of federal funding, MRCCC, Seqwater, Burnett Mary Regional Group, Alluvium Consulting, Noosa and District Landcare and willing landowners.

Young trees behind a fence
The trees at Ubi station grow fast.(Rural ABC: Jennifer Nichols)

Erosion Repair Wish List

The MRCCC would like to repair at least 35 more of the worst eroded areas along the 320 kilometer long river.

“If we had $50 million, we could probably fix them all,” Wedlock said.

“There is an investment strategy that we have prepared, so everything is doable, and we can’t do everything at once either, so the next 10, 20 or 50 years we have work ahead of us.”

Showing a downstream river repair site which is now overgrown.
The first river repair site prior to restoration work at Kenilworth in 2015.(Provided: Alluvium Consulting)

Ms Carter said she and her husband would strongly encourage other landowners to get involved.

“This project has been a tremendous success and we are overwhelmed with the support we have received from all stakeholders. They have all worked together so well, it is a huge honor for all of them.”

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