The company is complying with its licence for releases from the mine, a spokesperson told ILN.

“Illawarra Coal has been working constructively with the Office of Environment and Heritage since 2004 in relation to the company’s licensed discharge to Brennan’s Creek, near the West Cliff mine.

“During this time the company has undertaken a number of studies to investigate the water quality of the discharge and has met the requirements of all time-based targets for delivery of relevant reports to Office of Environment and Heritage.

“We will continue to ensure we improve our environmental performance through robust scientific based research.”

Greens MP Cate Faehrmann said West Cliff operated under an environmental protection licence that did not require limits on the pollutants that were of concern.

She said salt, nickel, zinc and turbidity were the pollution problems from the mine but the Environment Protection Authority only had discharge limits on oil and grease, pH and suspended solids that were not linked to any environmental damage.

"The reason Illawarra Coal has not faced any fines for the ongoing, chronic pollution it spews into a Georges River tributary is because the pollution is effectively sanctioned under the government's current pollution regime," Faehrmann said.

BHP says independent research shows there is minimal impact on the ecology of Brennan’s Creek from West Cliff mine.

“The company remains committed to working with government and local communities on this issue," the spokesperson said.