July deadline for Watermark decision

The future of a major coalmine proposed for the NSW Liverpool Plains will be decided in July after Federal Environment Minister Greg Hunt extended the deadline.

In February Mr Hunt referred the giant Shenhua Watermark mine, proposed to be built alongside rich farmland near the regional centre of Gunnedah, for independent scientific analysis of its impact on groundwater.

The minister made the referral after meeting with farmers to hear their concerns about the impact of the mine, which will extract 10 million tonnes of coal a year for 30 years.

On Thursday the Independent Expert Scientific Committee monitoring coal mining reported that there were "information gaps" in the mine proponent's water impact studies that had to be addressed.

The IESC said additional monitoring and better modelling of groundwater impacts would be needed if the mine progressed.

The committee also identified risks to groundwater from the combined impact of Watermark and another proposed mine nearby, BHP Billiton's Caroona Coal Project, and the need for more work to determine impact on local trees and plant life.

It said more monitoring would be needed during the mine's operation.

In a statement, Mr Hunt said the IESC advice would be taken into consideration.

"To ensure there is adequate time to properly consider the advice, the timeframe for assessment has been extended by 40 days," he said.

The new decision deadline is July 9.