THE state's environment watchdog has fined Werris Creek Coal for an uncontrolled water release after heavy rain earlier this year.
The NSW Environmental Protection Authority (EPA) issued the $15,000 fine to the company, which is a subsidiarity of Whitehaven Coal, for an alleged uncontrolled water discharge on February 18.
It is alleged by the EPA that the mine failed to maintain a sediment basin in a proper and efficient manner.
EPA regulatory operations manager Lindsay Fulloon said the mine allegedly failed to drain a sediment basin within the regulated five-day period following previous heavy rain.
"Mines are required to maintain management systems which ensure sediment dams are appropriately managed so that the design capacity is available to capture sediment and prevent it from being unnecessarily discharged into our streams and waterways," Mr Fulloon said
"In this instance, Werris Creek Mine allegedly failed to treat and drain the water within the sediment dam following a previous rainfall event, which meant the full design capacity of the dam was not available when the area experienced further heavy rain on February 18."
The water escaped into the catchment of Werris Creek and contained potentially harmful pH levels as well as elevated levels of sediment.
"Proper management of dam water levels is a regulatory requirement and it is vital that mines manage water levels between rain events," Mr Fulloon said.
"The EPA alleges that the pond had not been drained since February 3, 2020, despite further heavy rain on February 4 and February 13, 2020."
A Whitehaven Coal spokesperson said the company would learn from the incident.
"This was a regrettable incident and we have taken steps to ensure our controls and management practices are appropriate to avoid such incidents in future," the spokesperson said.