While recent rains filled the catchment, advocates are warning that the Mary River is still threatened by climate change and by thirsty residents and crops outside the catchment.
The Mary River runs for 310km from Maleny to Hervey Bay where it flows out through the Great Sandy Strait, part of the Great Barrier Reef Marine Park.
The river is home to at least two endangered species not found anywhere else in Australia or the world — the Mary River Cod and the Mary River Turtle — and dozens of other endangered and vulnerable species of flora and fauna.
The river and its banks are badly degraded by European settlement so millions of dollars are being spent researching and restoring riparian vegetation and aquatic breeding grounds.
Historical photo of sand and gravel mining on the Mary River. PHOTO: supplied
These funds are mainly to protect the Great Barrier Reef Marine Park, including Great Sandy Strait, from sediment run off caused by riverbank erosion and flood recovery from the record 2022 floods.
The Mary River flows into the Great Barrier Reef Marine Park. IMAGE by the Great Barrier Reef Marine Park Foundation
The restoration projects show great promise but Mary River Catchment Coordinating Committee (MRCCC) Operations Manager, Brad Wedlock, says extraction of drinking and farming water for the Sunshine Coast and Brisbane, combined with climate change, pose major threats to the Mary River.
MRCCC Operations Manager Brad Wedlock. PHOTO: Brea Martin
‘There’s no point rehabilitating river banks if you don’t have the water,’ Mr Wedlock said.
‘The river loses about 10 per cent of stream flow each decade. Climate change means the landscape is getting hotter and more evaporative. One per cent more evaporation equals five per cent less stream flow.’
‘We’re heading into a period where the condition of the river could be quite bad.’
Mr Wedlock said while the Mary River was flowing after good rain in 2024, it slowed to a trickle every Spring and water extraction to the Sunshine Coast and Brisbane was not helping.
Sections of the Mary River are reduced to a trickle in the dry season. PHOTO: MRCCC
Baroon Pocket Dam is on Obi Obi Creek (a tributary of the Mary River), the wettest section of the catchment’s headwaters. SEQ Water transfers water from the dam to the Sunshine Coast and northern Brisbane through the Northern Pipeline Interconnector, built during the Millenium drought.
‘Before the pipeline, that excess water went into the Mary River,’ Mr Wedlock said. ‘Now the Mary gets no stream flow from Obi Obi Creek which runs dry in Spring. That wouldn’t happen if Baroon Pocket wasn’t sucking out water.’
‘We need to change how water is supplied to urban populations. Inter-basin transfers from the Mary River to the Sunshine Coast and Brisbane could be replaced with tanks, recycling and desalination.
‘The Mary River is not a Magic Pudding supplying water to endangered species, townships in the catchment, irrigators as well as the Sunshine Coast and Brisbane.’
While the MRCCC lobbies for an end to water extraction, teams of scientists are working hard on research and restoration projects run by the MRCCC, the Burnett Mary River Group (BMRG), Griffith University’s Rivers Institute and Alluvium Consulting.
These projects have delivered good and bad news. The good news is riverbank stabilisation projects using pile fields and revegetation are working.
Pile fields are rows of wooden piles driven into damaged riverbanks to slow water flow and build up sediment. New vegetation is planted around the piles, which break down over time, leaving a stable, vegetated riverbank.
Pile fields on the Mary River. PHOTO supplied by the MRCCC
Misko Ivezich is an environmental engineer specialising in fluvial geomorphology (the study of rivers and their landforms). For the past ten years he has worked on Mary River rehabilitation projects through his employer, Alluvium Consulting.
Misko Ivezich PHOTO: supplied
Mr Ivezich does helicopter surveys of the catchment and has seen major changes to river.
‘I look at the physical shape of the river which has changed due to the degraded riparian zone and sand and gravel extraction making the river channel wider.’
He said when the riverbanks were degraded, floodwaters scoured the river channel further.
Degraded riverbanks at Kandanga. PHOTO: Misko Ivezich
‘Some reaches of the Mary River are three times wider than they were 50 years ago which means reduced habitat in the main channel for native species fish and turtles. They need the deep pools that form within a narrower river with vegetated riverbanks,’ Mr Ivezich said.
‘There are still tributaries such as Obi Obi Creek, Elaman Creek and Six Mile creek with well vegetated banks and deep pools providing good habitat for endangered species.’
Mr Ivezich said the Kenilworth reach was one of the most unstable reaches of any river in South East Queensland with some river banks retreating up to 50 metres during the 2011-2013 floods.
He said restoration work over the past ten years meant the banks held stable through the 2022 floods.
Before and after photos of Mary River rehabilitation at Kenilworth. PHOTOS supplied by MRCCC
‘What’s been achieved is quite remarkable.’
Big tick for restoration work from landholder
Mary Valley landholder, Ian Mackie, has high praise for riverbank stabilisation works completed at his property, Kalbilli Farm, on Walli Mountain Road three years ago.
‘The property lost acres of land to erosion in the past. As a farmer, my main priority was not losing land. I was shocked when the MRCCC told me sediment runoff from the Mary River was the main source of pollution to the southern end of the Great Barrier Reef. Everyone loves the reef and when I heard our reach was one of the main areas of sediment runoff, it was “conversation over, let’s do this”.’
Mary Valley landholder Ian Mackie. PHOTO: Sam Thies
A team involving the MRCCC, the Great Barrier Reef Foundation, BMRG and Alluvium Consulting did the works on Mr Mackie’s property, which he said was initially ‘intimidating because of the scale of the project and all the heavy equipment’.
‘The team removed 10,000 cubic metres of land, put in 120 piles and planted 5,500 fast growing natives. They were respectful of being on private property. They maintained the trees and three years later the riverbank looks fabulous. There was no erosion in the 2022 floods. I’m confident there will be no more loss of land on that bank.’
‘I take my hat off to the team who did this work.’
Before and after images of rehabilitation works at Ian Mackie’s property. PHOTO: MRCCC
Endangered species declining
While riverbank restoration is working well, the bad news is research teams working on restoration projects have found declining numbers of endangered species.
Professor Mark Kennard is Deputy Director of the Australian Rivers Institute at Griffith University and an expert in hydro-ecology. He’s been researching the Mary River since he was a student in the 1990s.
Professor Mark Kennard
Now leading a river restoration project with $550,000 funding over three years from the National Environmental Science Program’s Resilient Landscapes Hub, Professor Kennard aims to ensure restoration work benefits threatened species such as the Mary River cod, Australian Lungfish and the Mary River Turtle.
‘It’s a beautiful catchment but it does have pressures from a long history of European settlement and agriculture, particularly dairy, forestry and urbanisation,’ Professor Kennard said.
The project he’s working on with the MRCCC, landholders, the BMRG and traditional owners has found declining numbers of endangered species.
‘We only detected Mary River Cod at a quarter of the 60 sites surveyed and the majority were mature fish with few juveniles which means they are not reproducing effectively. We found lungfish at a quarter of the sites but very few early life-stage lungfish.
Professor Mark Kennard with a Mary River Cod PHOTO: Luke Carpenter-Bundhoo
The same research project has found increased populations of the invasive Tilapia which may prey on early life stages of fish and baby turtles and compete with endangered species for food.
‘There is likelihood of endangered species extinction if we don’t do anything but extinctions can be avoided with good science,’ Professor Kennard said.
Cautious optimism
Despite the dire warnings, MRCCC President Ian Mackay is still cautiously optimistic about the future of the Mary River, based on improved behaviour of private landholders who own the majority of riverfront property.
MRCCC President Ian Mackay PHOTO: Brea Martin
‘I do feel optimistic about the Mary River because I see a lot of people working together on it, who see the benefits of working sustainably. I see dairy farmers capturing effluent and turning it into fertiliser and cattle farmers using watering stations away from the river so the cows are not trampling river banks.
‘There’s momentum for Mary River restoration. We have a wait list of landholders wanting to get involved.
‘There is increasing awareness of the river’s dynamics and threatened species and all the species that live there. People are learning to appreciate its high ecological value,’ Mr Mackay said.
Also optimistic about the future of the Mary River is the MRCCC’s Waterwatch coordinator, Shona Sengstock,who has 80 volunteers testing water quality every month across the entire catchment.
Local Waterwatch coordinator, Shona Sengstock. PHOTO: Brea Martin
The Waterwatch Program has been going since 2001.
‘It’s citizen science and we couldn’t do it without the volunteers,’ Ms Sengstock said. ‘We get so much information to understand the catchment.
‘I’m deeply connected to the river. My family have lived here for 30 years and I swam in the Mary as a kid.
‘The Mary River is in a good state in sections. There are some really degraded areas and really special areas.’
Mary River photo by Karina de Raadt
Alluvium Consulting’s Misko Ivezich is also optimistic with caveats.
‘I have mixed emotions after working on Mary River projects for over ten years.
‘It’s been sad to see how the river has declined over the past 100 years and disheartening to see the impact of the 2022 floods but the Mary River has a lot of potential for recovery,’ Mr Ivezich said.
‘Funding to help protect the Great Barrier Reef Marine Park has super-charged recent restoration efforts.
Stable banks need protection too
‘However, restoration funding is targeted to the most eroded sections of the Mary River to prevent sediment running into the Great Barrier Reef Marine Park. Government policy and funding is also needed where the riverbanks are stable so they can be preserved. Landholders need incentive to protect and enhance riparian zones.’
Ultimately, the MRCCC’s Brad Wedlock believes it’s community who will make the difference to whether the Mary River is restored to a healthy, thriving river system.
‘I grew up near a park on the Mary River in Maryborough. We swam and fished on the river. My grand-father lived at Tuan and built fishing boats.
‘Over 30 years ago I saw a dozen lungfish washed up over the barrage and showed my grandfather. He said ‘They’re lungfish. They live for more than 100 years. They shouldn’t be doing that.
‘He rang the environment department and the Conservation Council to tell them and that was an influence on me. I remember as a kid thinking “someone cares about this stuff”.’
‘It’s the people, the landowners and the community who will do the work. Communities are faster and more innovative at solving problems than governments can be.’
To discover more about the Mary River go to www.mrccc.org.au
Kingfisher photo by Karina de Raadt
PHOTO of Mary River with sandbank at top of story by Karina de Raadt
This news feature was funded by the Local and Independent Media Association (LINA).
