THE NSW government has tightened the pollution licence of a coal-fired power plant near Lithgow that is releasing toxic metals into a river that feeds Sydney’s drinking water supply.Delta Electricity, the owner of Wallerawang power plant, must now monitor heavy metals and pollutants such as arsenic flowing into a channel that enters the Coxs River and report back to the government every three months.But the latest results show that Delta is still polluting the river above safe guideline levels in some instances, more than two years after the government was warned that discharges from the plant were killing aquatic life.The amount of copper leaching into the river remains above Australian and New Zealand Environment and Conservation Council guidelines, at levels that can be deadly for fish and other river creatures.The Department of Environment, Climate Change and Water believes considerable progress has been made towards cleaning up the power plant. Some corroded machinery in the plant may have to be replaced, and stricter limits have been placed on how turbid the water from the plant’s cooling towers can be before it is flushed out.”The [department] remains committed to achieving improvements in the water quality of the upper Coxs River by using its regulatory and licensing powers to achieve best practice environmental outcomes,” a spokeswoman said.Independent water quality tests taken in 2008 and 2009 established that the river near the power station was contaminated with high levels of heavy metals including zinc, copper and manganese, 125 times more sulphate than surrounding streams and just 5 per cent of the oxygen that most fish need.The river’s acidity levels were up to 1000 times higher than in nearby creeks, and the river was 80 times saltier than it should be.Most of the salinity was caused by the use of recycled coalmine water in the power station, and current levels are still well beyond healthy guidelines for freshwater fish.Delta has been acquiring recycled water with high salt levels from a nearby coalmine as river levels plummet due to the drought. The company is aiming to develop a reverse osmosis plant at the power station, which should reduce water salt levels.The latest discharge results come as Delta appeals against a Land and Environment Court ruling that could allow it to be prosecuted by a local environment group, in a test case with implications for industrial emissions around the state.The Blue Mountains Conservation Society is mounting the case with the help of the Environmental Defender’s Office of NSW in an effort to restrict all harmful pollution.”I think it’s a positive, in that they’re requiring additional monitoring, but it’s a long way from actually solving the problem by stopping the discharges into the river,” said the society’s president, Tara Cameron. The group is waiting to see whether the Land and Environment Court will uphold its original decision to cap the costs of a court case at $20,000 before proceeding with its case.”The upper Coxs River is basically dying because of the amount of salt and heavy metals being poured into it,” Ms Cameron said, citing years of work undertaken by a University of Western Sydney researcher and by local ”Streamwatch” volunteers.”The case is also about highlighting a much more general issue around the state in that companies are required to monitor their pollution but not necessarily stop polluting.”