The EPA had negotiated with the company to significantly reduce the salinity pollution of the Cox's River but Faruqi said it was still much greater than the background levels.

“That means that the salinity in the river could be increased, degrading the environment and water quality,” she said.

“The EPA should be using its power to ensure that the Cox's River, which is in the Hawkesbury-Nepean catchment and feeds into Sydney's drinking water, is not polluted by wastewater from coal mines.

“If a mining corporation cannot put in the technology to protect the Cox's River from polluted water discharge then there are real questions about why it is being allowed to operate at all.

“Under no circumstances should we be putting the profits of coal mining companies above our environment and precious drinking water catchments.”

To comply with the EPA's strict conditions Centennial is required to make a significant financial investment in technology and infrastructure, the company said in a statement to ICN.

"Springvale mine must comply with strict limits imposed on both the quantity and quality of all water discharged," it said.

"Claims the EPA have failed to impose strict environmental conditions on the future operations of Springvale colliery are incorrect.

"The EPA, as a condition of Springvale continuing its mining operations, has imposed a range of conditions that

will require Centennial to meet specific water quality targets.

"Centennial is committed to a catchment wide management of environmental impacts and, as such, has worked with the EPA to ensure the strict environmental standards they have imposed are integrated and achievable.

"These conditions and targets established will deliver an improved water quality outcome for the entire catchment."

Centennial has assessed the impacts of the water discharged to the Coxs River within its Environmental Impact Statement (EIS) and supporting documents, the company said.

The EIS for the Springvale mine extension project included a detailed hydrogeological model of predicted water volumes expected from the mine.

This model, developed by the CSIRO is considered best practice, according to Centennial.

"These assessments have concluded that the

impacts are manageable within the constraints of the draft conditions proposed by the Department of Planning and the recommendations made by the Planning Assessment Commission," it said.

The Springvale longwall mine extension project has received a favourable review from the New South Wales Planning Assessment Commission.

PAC recently completed a review of the project, which still needs federal environmental approval along with a successful PAC determination as part of getting the state’s environmental go-ahead.

In its review the three-member PAC panel said it was important to view the project in the context of state’s power supply especially as Springvale was the only local mine supplying the Piper Power Station that produces about 15% of NSW’s electricity.

“The commission has carefully weighed the key areas of concern, including discharge impacts on the region’s water resources and swamp impacts, against the significance of the resource and the socio-economic benefits,” PAC said.

“The commission is satisfied that the project’s benefits as currently understood outweigh its potential impacts, and on balance is approvable.”