The $1.2 billion project has passed exhaustive NSW environmental approvals with Shenhua boosting its chances years ago by buying up farms and property in the project area.

While federal environmental approval was expected on March 13, Hunt told a media conference at Tamworth Airport on Friday that he had sent the application back to the Canberra-based Independent Expert Scientific Committee.

It’s known as the first time a coal project has been sent back to this agency for a second review, with IESC last looking it over in 2013.

“In short I have stopped the clock on the Shenhua project to seek additional advice on protecting water resources and aquifers from the best experts on groundwater in the country,” Hunt said while flanked by National Party figures Kevin Anderson and Barnaby Joyce.

“That was not just in response to requests from the community and Barnaby Joyce, but also because it was the right thing to do to get the right science, because you never take risks with water, with the future.”

Although the move was predictably welcomed by agricultural and anti-coal mining groups, Shenhua Watermark project manager Paul Jackson told the ABC he was not surprised Hunt made the decision.

"We have spent $730 million and we have been waiting eight years and now we've got to wait another period of time," he said.

"It won't take an extra couple of years. I think this will be done and dusted by the end of April.

"The scientific assessments are there, they have been peer-reviewed by the best experts in the country, both through us and through the [NSW] Planning Assessment Commission, which is an independent process. For us, it won't really mean too much."

Regarding Jackson’s faith that the approvals will be in by the end of April, this is about one month after the NSW election is held (March 28). A poll last week revealed that the incumbent Liberal party-led Baird government had narrowed to a 53:47 lead on a two-party preferred basis.

The Queensland Liberal National Party’s unexpected electoral defeat from the January 31 election rocked the federal government while Prime Minister Tony Abbott has been dogged by leadership challenge speculation since.

The Watermark open cut project is targeting up to 10 million tonnes per annum run of mine over 30 years with about 84% of the saleable coal to be of a metallurgical grade.