South Australia's Environment Protection Agency (EPA) does not know how an Adelaide creek turned white, but has determined a nearby private quarry — which is in breach of its mining conditions for sediment pollution — is not the cause.
In September, the EPA's Emergency Response Team was called to Horsnell Gully Conservation Park, near Magill, after locals reported that Third Creek had turned "milky white".
The EPA determined from real-time monitoring that the white discharge had not come from Hanson's White Rock Quarry, which water from Third Creek runs directly through.
The agency said "an isolated event such as paint or another substance" was likely the cause, but was not "able to confirm the source on this occasion".
Under its current licence, Hanson commissions regular water quality monitoring by independent consultants and reports the results to the relevant departments.
The ABC's request to see those reports is currently being processed by the EPA and is subject to consultation with the mining company.
The Department of Mining and Energy, which is the lead regulator for the quarry, issued a compliance order to Hanson for breaching its mine operations plan, regarding the "off-site release of sediment-laden stormwater into Third Creek" in May this year.
Hanson wants to expand the existing quarry site and is currently revising its proposal, with a new version to be sent to the department for consideration in March.
'Brown milkshake' creek
Joshua Zeunert has lived by Third Creek, which runs into the River Torrens, for almost four years and said this was not the first time something has been "very wrong" with the creek.
"Especially during the last two winters, it would look like a brown milkshake," he said.
"Some of those events were particularly milky white."
White Rock Quarry has operated within Horsnell Gully for more than 70 years and was acquired by Hanson in 2007.
The quarry also uses a portion of the adjacent conservation park for water supply and stockpiles, which it is allowed to do because the mine pre-dates the establishment of the protected area.
The EPA said in a statement that it "encourages its licensees to engage with their communities and supports companies sharing and publishing data to their websites", which White Rock Quarry currently does not.
Mr Zeunert said he feels like residents are the only ones trying to hold the mining company to account.
"The EPA is there to protect the environment, so are they doing that or are they protecting the interest of the quarry?" he said.
Residents question EPA response
The EPA said that sediment discharges from the quarry "are currently not acceptable".
"Resolving this issue requires a program of progressive improvements, monitoring and assessment over a period of time," it said.
"The EPA's focus is to assess if Hanson has taken all reasonable and practicable measures."
Residents Against White Rock Quarry spokesperson Jim Bastiras said if the white discharge was paint, it needed to be properly investigated to ensure it doesn't happen again.
"The EPA made a rather concerted effort to deny that the white milky water had anything to do with the quarry," he said.
"Yet it failed to say what it actually was and where it was coming from."
Mr Bastiras said he feels that the community has been left in the dark.
"We feel that they're primarily interested in appeasing public concerns with rhetoric and irrelevant distractions more than achieving actual positive outcomes for the community and the environment," he said.
A Hanson spokesperson said it considered "responsible environmental practices to be a key priority" of the mine.
"We have made every effort to ensure continuous improvement in water quality management at the site," they said.
"Hanson has engaged an independent company specialising in sediment management and water quality solutions to assist with improving water quality."
Regulating mines
Hanson is currently undertaking an Environment Improvement Program (EIP) and is required to build a second sediment basin to further manage surface water during high rainfall events.
"The EIP includes a monitoring program to assess the success of improvements invested at the site and inform further action," the EPA said.
Environmental engineer Gavin Mudd said those types of programs should not delay repercussions if a mine is found to breach its conditions.
"We can't just wait another five years until the plan is finished to actually get somewhere," Dr Mudd said.
"Ongoing sediment pollution can prevent oxygen getting into the river and it can prevent light from getting into the water, which can definitely be problematic to aquatic ecosystems."
"If it was paint discharged it should be pretty easy to get some samples, get them tested and work out whether it was actually paint in the water."
Dr Mudd said it had become common practice for mining companies to monitor their own environmental impact and suggested that regulators and the industry can do more to improve transparency.
"How do you make sure that there is good independence in that data, which is largely just between the company and the government?" he said.
"They could resource the community so they can go out and sample."
"But at the minimum we have to make everything public."
