The authority’s submission is at odds with plans by the New South Wales government to change the planning process to make economic benefits the “principal consideration” in assessing mining proposals.

The authority's submission said damage to infrastructure, watercourses and swamps from longwall mining had already occurred, including on the Upper Canal, which was the only way water could be transferred to Sydney from upper Nepean dams, according to a report in the Sydney Morning Herald.

The authority recently received advice on “the long-term potential for damage” from longwall mining, it said.

Longwall mining involves removing a panel of coal along a face up to two kilometres long.

The Office of Environment and Heritage says it can cause land above to destabilise and collapse and create cracks under streams or other water bodies that might lead to water loss. It can also contaminate water.

Environmental group the Total Environment Centre has called for a parliamentary inquiry into the Sugarloaf controversy and more generally, into the damaging impacts of longwall mining and government decision-making on approvals.

A large section of Sugarloaf State Conservation Area in the lower Hunter was destroyed by massive subsidence from Glencore's West Wallsend Colliery.

According to TEC executive director Jeff Angel, drained swamps and massive cliff collapses are littering the Newnes Plateau in the Blue Mountains, while farms in the Hunter Valley have been rendered unviable as waterways cease to flow.

“The issue also calls into question the government's pro-mining consent policy championed by Mines Minister Chris Hartcher. It will make it all the harder to impose environmental controls,” he said.

Glencore was quick to issue a response in which it noted, “we are fully committed to work with all parties to remediate impacts in a remote area of the Sugarloaf State Conservation Area”

“Glencore’s underground mining operations within the SSCA are undertaken in accordance with a Part 3A Project Approval received from the NSW Department of Planning and Infrastructure and its approved Extraction Plan / Subsidence Management Plan,” the Glencore statement said.