Environmentalists say the state government's decision to approve a longwall mining plan at Dendrobium breaks a promise Premier Barry O'Farrell made while in opposition to protect the state's drinking water.
In 2007, the then-opposition leader spoke at a rally opposing mining in the Wyong water catchment area on the Central Coast. He promised that, if elected, his government "will ensure that mining can't occur in any water catchment area ... no ifs, no buts. A guarantee".
But the Nature Conservation Council of NSW said the O'Farrell government's approval of a scaled-back plan for longwall mining at BHP Billiton's Dendrobium mine at Mt Kembla flew in the face of that promise.
"More than four million people depend on Sydney's catchment for their drinking water," conservation council chief executive Pepe Clarke said. "Damaging our own water supply for the sake of coalmining is reckless and irresponsible."
He said the mining, which would take place a few hundred metres from the Avon water supply dam, posed a serious threat to at least 12 swamps in the area.
"The proposed longwalls are more than 300 metres wide and will cause severe subsidence and significant cracking that will very likely drain up to 12 upland swamps," he said. "These swamps are endangered ecological communities and provide a reliable supply of water, especially during long dry spells."
Mr Clarke said the requirement that BHP Billiton submit a compensation package for possible negative impacts was a waste of time as several submissions pointed out that, once damaged, the swamps could not be repaired.
"This decision is a betrayal of the trust that people place in government to protect our environmental heritage and water supply from harm," Mr Clarke said.
Planning and Infrastructure Minister Brad Hazzard said, while he was unaware of the context of Mr O'Farrell's "no ifs or buts" promise, it was not relevant in the Dendrobium instance as it was not an approval granted by the Liberal government.
"This is not an initiating application, this is a continuing application," Mr Hazzard said. "My understanding is the actual development approval was given back in 2001 under the former Labor government."
Mr Hazzard said the issues of the catchment "were deemed likely not to have any significance".
"But one of the environmental issues is potential damage to some of the swamps. As I understand it, the conditions require the company do quite a bit of work to address those issues. The price of business in NSW also should include the price of ensuring the environment is appropriately protected and that's what we're aiming to do."