Mine operator South32 was recently given approval to create two more 305-metre longwall mines at its Dendrobian mines, which will run under the metropolitan special area catchment near Appin.

The catchment – which supplies Macarthur residents with their drinking water – is a large area located in between Appin, Mittagong and Wollongong, and takes in dams including Cataract, Avon, Nepean and Cordeaux.

Special area catchments are considered so precious and sensitive that the general public is not allowed to even walk near most of the areas.

Wollondilly MP Jai Rowell said he believed the areas should be “off limits” to mining.

“Mining has a place in Wollondilly and has big benefits to the area, but special area catchments should be off limits,” he said.

“I have concerns over any mining in water catchments and I think we should leave the special area catchments alone.”

Mr Rowell’s colleague, Camden MP Chris Patterson, could not be reached for comment.

NSW National Parks Association Macarthur branch member Julie Sheppard said the state government’s decision was “deeply disappointing” but “entirely predictable”.

Ms Sheppard has been involved in protests against expansion of Wollongong Coal’s Russell Vale longwall mine – which also planned to mine under the metropolitan special catchment area.

The state government has so far refused to approved Wollongong Coal’s proposal.

She said the South32 decision was another example of the dollar taking precedence over the environment.

“The government is looking at the issue of the economy and jobs but not the issue of water security,” she said.

“This is where Macarthur gets its drinking water from – not Warragamba Dam.”

Ms Sheppard said swamps in the catchment that played a vital role in storing drinking water supplies had already been damaged due to mining.

“The full amount of rainfall isn’t going into storage (reservoirs), it’s going through cracks created by mine subsidence,” she said.

Macarthur MP Dr Michael Freelander (Labor) said while it was a state government decision, it was an issue that also concerned himself and his federal government colleagues.

“It’s a federal issue too because we should be doing what we can to move away from fossil fuels,” he said.

Dr Freelander said he “didn’t hold out a whole lot of hope” that Premier Mike Baird would reverse the decision.

The mines are expected to create 400 more jobs and will supply a nearby steel mine as well as overseas markets.

As part of the approval process, the government said the mines could be cut to a height of 3.9 metres – not 4.6 metres like the five other Dendrobian mines.