The seagrass mounds of Port Geographe were a visual and odorous blight for residents. But as Georgia Loney writes, researchers have brought significant relief.
Busselton man Mark Jacobsen is doing something that not long ago would have been near-impossible. He’s taking a walk along the sandy beach at Port Geographe.
Just five years ago the beach just near Busselton, 200km south of Perth, was an environmental nightmare, notorious for 2.5 metre-high ‘mountains’ of rotting seagrass that emitted foul-smelling hydrogen sulphide and made the lives of local residents a misery. Now there are hopes the nightmare is over.
In 2015, the WA State Government finished a $28.15 million project to re-engineer the groynes at Port Geographe, following landmark research into seagrass dynamics from Edith Cowan University and the University of Western Australia.
Since then, there’s been about a 90 per cent reduction in the sea-wrack build-up on the western side of Port Geographe, according to the Department of Transport.
The hydrogen sulphide fumes, described as a pervasive rotting egg stench that sparked complaints of nausea, headaches and respiratory problems, have greatly diminished.
For residents, it’s been a near 20-year saga, stretching back to the mid 90s when property developers built the multi-million dollar marina and canal development. It received environmental approvals, but authorities seriously underestimated how much seagrass would be trapped on the western side of the marina each winter.
By 2012, more than 100,000 cubic metres of sea-wrack was accumulating on the beach, forming metres-high piles, and stretching for about 1.5km. The Department of Transport would then send in trucks and excavators to move the seagrass to the other side of the harbour, making the area look and sound like a construction site. Health authorities discouraged swimming or walking because of concerns over hydrogen sulphide emissions.
Mark Jacobsen, who manages the nearby Busselton Beach Resort with wife Toni, remembers when the seagrass piles were so high, it was impossible to see the sea.
“It was a mountain of sand and weed altogether, and it was high – 9 feet high,” he says.
The rotting egg stench affected visitors who had hoped for an idyllic beach holiday, says Toni Jacobsen.
“I know for the previous managers, it really affected the guests here, because they’d come in and complain all the time, saying that terrible smell, you can’t get on the beach,” she says.
“In those days there was no beach. There was just seaweed.”
Local businessman Ray Mountney has lived in Port Geographe for nearly 20 years, since before the marina was constructed.
“I think the difference is not whether the seaweed was or wasn’t there, but whether it was allowed to escape under the normal storm patterns, that (used to) clear all of the weed, literally overnight,” he says.
Mr Mountney remembers the rotting egg stench vividly.
“It wasn’t pleasant, there’s no doubt about that. People who would come for the first time, tourists and visitors, they’d turn their nose up and say, God, what’s that? What’s that?”
The Port Geographe Action Group (PGAG) lobbied government for decades for a solution, stressing the issue was one of public health.
PGAG chairman Peter Maccora says the area was near uninhabitable when the problem was at its worst. In 2009, the group released a toxicology report that indicated hydrogen sulphide levels in the area exceeded the World Health Organisation's standards.
“You couldn’t really live there, because of the problems with hydrogen sulphide,” he says.
“If it hadn’t been a health issue, I doubt the government would have provided the funds (to reconfigure the groynes).”
The problem was also expensive. From 2009, the then-developers had refused to pick up the $1 million-plus bill for the annual bypassing work, forcing the City of Busselton to break into the developer’s $3.8 million bank guarantee. In 2012, the developers went into liquidation.
The question loomed – how was this decades-old problem going to be fixed?
ECU and UWA researchers had already found a potential solution.
In a landmark 2010 study into seagrass wrack dynamics — commissioned by the shire council and the Department of Transport — they recommended reconfiguring the groynes.
The research team, led by UWA’s Professor Carolyn Oldham, together with ECU’s Professor of Marine Ecology Paul Lavery and Dr Kathryn McMahon, and Professor Charitha Pattriaratchi (UWA) and Dr Tony Chiffings (consultancy DHI), had spent two years studying the way seagrass moved in Geographe Bay.
Professor Lavery says he was “flabbergasted” by the enormity of the seagrass accumulation.
“It was astonishing,” he says.
“When you approached it from the water, from the ocean-side, you were effectively driving into a two metre high cliff of this material.
“The water in front of it was full of the wrack as well, and you could see bubbles of rotten egg gas coming up from the bottom of the ocean and bubbling out. It really was quite extraordinary.
“The first thing that struck me was how come we haven’t heard a lot more about this already, and how on earth have the people who have been living near it been coping with it for all these years?”
Dr Kathryn McMahon — a senior lecturer in the Centre for Marine Ecosystems Research — says it seemed the problem was the worst of its type in the world.
“The seagrass meadows in Geographe Bay are some of the biggest in the world, so there’s a lot of seagrass out there that can wash up on the beach,” she says.
“The way that the port was constructed was that it was fantastic at trapping it, and stopping that natural movement on and off the beach.”
Lavery says it is important to remember that seagrass is also a vital part of the marine ecosystem, so removing it permanently was not an option.
“The thing about seagrass is that it’s absolutely critical to maintaining a healthy coastal environment. The waters off Western Australia are what we call oligotrophic, which means they are very low in nutrients,” he says.
“So if you’re going to keep the system healthy and productive, it’s very important that the nutrients that are in the system are recycled.”
McMahon says the research team was multi-disciplinary, and included seagrass biologists and ecologists, biochemists, engineers and hydro-dynamic modellers. Researchers used a unique model to determine how to reduce seagrass accumulation.
“What we did was combine the biology and ecology of the plants, with the natural movement of the water in the system and tried to predict what would be the best configuration of the groynes that would minimise trapping of wrack,” she says.
Lavery says it became evident that non-structural solutions were either unfeasible or impractical.
“That’s when it came down to, we have to redesign the thing,” Lavery says.
Two years after the release of the landmark report, its recommendations were put into practice. In November 2012, then Transport Minister Troy Buswell announced the State Government would fund the groyne reconfiguration, and work began in 2013.
The Department of Transport says it is satisfied with the results of the reconfiguration.
Department manager of maritime projects James Holder praises the work of researchers.
“Being able to tap into some experts in this field was a fabulous resource,” he says.
“Their contribution to the project, critically the development of models able to predict and represent seagrass behaviour in Geographe Bay, that was a world-first.
“The experts’ development of the model and determination of various parameters to make that work, was critical to the project realising its potential.”
Mr Holder warns there is no perfect solution to the historic problems at Port Geographe, and there will always be a need for some coastal management to sustain the development.
But he says the significant improvement is encouraging.
“The current estimate is that there’s less than 12,000 cubic metres of seagrass wrack on the western beach following the 2016 winter. It is in the order of a 90 per cent improvement. I think we’d take that any day of the week in terms of where we’d been,” he says.
“Every winter season is going to deliver slightly different outcomes depending on the severity of the storms. We still think that there’s a settling in period underway, and we’ve always said it would take a number of years to see optimum performance outcomes achieved there, so there's still changes happening."
Mr Holder says the reconfiguration has significantly reversed the erosion immediately next to the Port Geographe, at Wonnerup, but adds he is aware of concerns over erosion further east, where modelling has indicated complex coastal processes are at play.
He says the department would continue to work closely with the City of Busselton to monitor erosion at East Wonnerup.
The City of Busselton is also hopeful that the decades-long saga of the problems at Port Geographe is drawing to a close.
The City’s property and corporate compliance manager Sharon Woodford-Jones says the general response from the community, to the western side of the groyne, was one of “relief and exhilaration.”
Mayor Grant Henley says the groyne reconfiguration has created optimism in the area.
“No-one’s going to snap their fingers and make it go overnight, but the science and the evidence so far seems to indicate that things are moving in the right direction,” he says.
PGAG chairman Peter Maccora says he remains concerned over erosion on the eastern side of the marina but praises the researchers who worked to find a solution.
“The government had to build a case that if they were going to spend $30 million there was going to be a positive outcome,” he says.
“The studies all allowed the government to go back to parliament to try to fix this.
“We just have to wait and see what nature dishes up in the next couple of years.
“But last winter, there were no trucks, and the days of spending $2 million a year in beach works appear to be over.”
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