Mr Humphries told The Leader “I do not support the extension of the Vickery coal mine”.

“A 10 million tonne coal mine operating adjacent – less than 500 metres – to the Namoi River is not acceptable by any standards,” Mr Humphries said.

“Whilst technically not a floodplain, typographically the area proposed is directly placed within the floodplain and will have an impact.”

A Whitehaven spokesman said the Environmental Impact Statement for the Vickery Project would address all the potential risks.

Mr Humphries said there were “more appropriate” sites for coal mines that were less contentious and risky than the Vickery extension.

“Agricultural land use and water resources are far more complex in nature [in the Namoi Valley] than other valleys, which dictates where and under what circumstances extractive industries such as coal mining should be allowed. I foresee further issues with the plan to relocate additional infrastructure from Gunnedah and the construction of an overhead rail viaduct and river crossing over floodplain and farming country.”

Boggabri Farming and Community Group spokesman David Watt said the farming community was buoyed by Mr Humphries’ support.

“I don’t think he’ll be alone,” he said.

“It’s such a no-brainer, once it comes across the desk of other politicians, they’ll form the same opinion.

“The pollution risk to the river is obvious – it’s happened in Queensland, Lithgow and the Hunter Valley. You can’t have a mine that close to a river.”