Elevated levels of ammonia have been discovered in a creek near Clive Palmer's Queensland nickel refinery.
The Department of Environment and Heritage Protection (EHP) reports that the results came from a water sample at Blind Creek near the Yabulu nickel and cobalt refinery.
Environment Minister Dr Steven Miles said the samples were taken in late June.
In March, Queensland Nickel Sales (QNS) advised EHP that ammonia had been detected in Blind Creek and nearby Alick Creek, at levels higher than the surface water quality limits in the company's environmental regulations.
The EHP conducted routine inspections of the refinery in April and June to assess QNS's compliance with its environment responsibilities.
Under the Environmental Protection Act, breaching the act can result in fines up to $2.6 million for a corporation.
Dr Miles said EHP would consider the latest sampling results (June 22) as part of its current investigation.
"While the refinery is in care and maintenance and is not currently in production, enforcement orders issued by EHP remain in place to direct Queensland Nickel Sales to ensure environmental protection systems at Yabulu keep operating," Dr Miles said.
"The department is now considering what actions, in accordance with relevant enforcement guidelines, might be taken against the company."
The inspections in April, and again last month, included water management practices, contaminated water storage, and key water management infrastructure," he said.
The refinery is located north of Townsville near Halifax Bay, which forms part of the Great Barrier Reef Marine Park and World Heritage Area.