SUTHERLAND Shire environmentalists are calling on Peabody Energy to release information on the state of the Waratah Rivulet, which supplies drinking water to the Woronora Dam.
They claim the company has failed to divulge the success or failure of its attempts to remediate the damaged riverbed.
The rivulet, which is in the Woronora special area and off-limits to the public, first hit the news in 2007 when cracks were discovered in the riverbed and some its waters disappeared underground.
The damage was blamed on longwall coal mining underneath the riverbed undertaken by the Peabody-owned Metropolitan colliery.
The National Parks Association of NSW has released a video documenting a visit to the rivulet by a group of environmentalists and Greens MP Jeremy Buckingham six months ago.
It shows unremediated cracks, as well as some of Peabody's remediation attempts.
But NPA Southern Sydney branch secretary Gary Schoer, who appears in the video, said no one has been able to find out if the damage to the rivulet was ongoing or if remediation was actually working.
"When we visited we found out the remediation is still proceeding," Mr Schoer said.
"We saw many cracks which had not yet been filled.
"But we don't know how extensive the damage is, or how successful the remediation is."
Mr Schoer said the NPA had been trying to meet with Peabody for the past six months.
The Leader asked Peabody to comment on the remediation, as well as Mr Schoer's claims about the delayed meeting, but did not receive a response.
Both NSW Environment Minister Robyn Parker and NSW Primary Industries Minister Katrina Hodginkinson, who is responsible for the Sydney Catchment Authority, also declined to comment on the state of the rivulet.
The Leader did not receive a comment from Sydney Catchment Authority by deadline.
Georges River Environmental Alliance secretary Sharyn Cullis, who visited the rivulet with Mr Schoer, said the damage she witnessed was horrifying.
"What I saw on a tour of inspection, inside what is supposed to be a protected catchment, really horrified me.
"The riverbed of the Waratah Rivulet was smashed.
"What should have been clear, clean water in the stream, which is 30 per cent of the inflow into the (Woronora) dam, was a murky orange brown.
"What should have been drinking water didn't look fit for a dog to drink," Ms Cullis said.
According to Ms Cullis, remediation attempts so far appeared to be "futile".
Mr Schoer said tests conducted by environmentalists had confirmed chemical changes to the water which flowed through the damaged areas of the rivulet, but said he did not know, and had been unable to find out, how much of this water was flowing into the Woronora Dam.
Should there be greater protection for the rivulet?