Conservation groups say the Springvale mine will weaken the protection of Sydney's drinking water. Credit:Wolter Peeters NSW Energy Minister Don Harwin said the new laws would allow the mine to continue supplying the Mount Piper power station, putting downward pressure on wholesale electricity prices and avoiding possible blackouts. Two months ago, the NSW Supreme Court upheld an appeal by non-profit group 4Nature against the extension of the mine, which would have prolonged its operation by 13 years. The group argued the extension would increase the amount of polluted waste water going into the Coxs River, harming the quality of Sydney's main water supply. Mr Harwin was asked on Monday if the government was interfering in the NSW judicial process but he argued it was "absolutely necessary to act now to ensure that we have a secure supply of power".

Springvale mine worker John Tilley faced an uncertain future. Credit:Wolter Peeters "We're doing what we need to do and we're doing what's in the interest of the people of NSW," he said. Mr Harwin said discharged mine waste water would be treated in a new plant due to be completed in 2019. Labor supported keeping the mine open as it extracts coal used to produce 11 per cent of the state's electricity. However, the party said aspects of the bill eroded environmental protection laws.

"They're using the potential threat to the state's electricity supply to then overreach and reduce important protections to the Sydney water catchment," opposition energy spokesman Adam Searle said. The new laws change the starting point for water safety testing, he said. Under the original law, companies had to prove an extension to a mine would keep water quality the same or better than if there were no mine in the area, Mr Searle said. But under the new legislation, mining companies now only have to prove further developments at a site don't make water quality any worse than their mine already does. "They're using Springvale as a Trojan horse," Mr Searle said.

Premier Gladys Berejiklian said the legislation provided sufficient environmental safeguards. "Those protections are there already and that was the premise by which I gave my support to the legislation," Ms Berejiklian said on Wednesday. "For me, a condition of supporting the legislation was maintaining water quality. That is a key priority for our government." But Mr Searle rejected Ms Berejiklian's assertions. "The Premier is talking rubbish and she doesn't know what she's on about," he said.

"If she's being honest with herself and the community, she will understand that her comments are not correct." Meanwhile, EnergyAustralia praised the government for passing the legislation, saying it would ease pressure on electricity prices. "This is what good policy and real political leadership looks like," EnergyAustralia's energy executive Mark Collette said in a statement. Centennial Coal said the approval would secure more than 600 jobs in Lithgow. However, the NSW Greens have accused the government of succumbing to pressure from coal and energy companies and sidestepping the courts.

"The government should let the court do its job, as the parties to the case were aware of the consequences of the decision and were prepared to negotiate a sensible set of orders," Greens MP Jeremy Buckingham said. Federal Environment and Energy Minister Josh Frydenberg supported the NSW government's move. "I'm sure that the government is working very hard to get the balance right between the sustainable and environmental practices needed and continuation," Mr Frydenberg said. However, 4Nature president Andrew Cox said the state government's decision was "abhorrent". Loading

"We're concerned that special legislation will effectively allow companies like Springvale to continue to pollute Sydney's drinking water catchments," Mr Cox said AAP