A fight has broken out over funding for monitoring the rehabilitation of a uranium mine.

Energy Resources of Australia (ERA) runs the Ranger uranium mine in the idle of Kakadu National Park. ERA, which is owned by Rio Tinto, wants to stop paying $2.5 million a year for the Supervising Scientist Branch independent monitoring agency, which it funds with the Commonwealth.

Associate Professor of Environmental Engineering at RMIT University, Dr Gavin Mudd, is one of the community members on ERA's independent technical consultation committee.

“That funding is no longer guaranteed for next year is a major concern,” Dr Mudd has told the ABC.

“This work is needed to give us confidence that what is done at Ranger actually works, including the restoration of ecosystems, how stable the landform is, the radioactivity and the surface and groundwater water quality issues.”

Dr Mudd says Ranger will likely need decades of rehabilitation monitoring, if the failures to rehabilitate other Northern Territory uranium mines is anything to go by.

ERA was forced to close the mine after a series of uranium leaks and spills into the Alligator Rivers system. It has until 2021 to close the doors.

The company has promised to have the mine site in pristine state to be included in the Kakadu World Heritage park by 2026.

Monitoring by the Supervising Scientist is meant to prove that.

“As ERA prepares to cease processing [uranium ore] at Ranger in January 2021, ERA sought a contractually permitted, periodic review of the terms of its longstanding research funding arrangement with the Commonwealth Government,” ERA chief executive Paul Arnold said.

“There has been no decision that ERA's contribution would cease.

“ERA is committed to working with the Supervising Scientist Branch, regulators and other key stakeholders with the shared goal of rehabilitating Ranger in accordance with the environmental requirements.”

Federal Environment Minister Sussan Ley has told reporters through a spokesperson “ERA is choosing to dispute its ongoing contribution under the Deed”.

“The role of the Supervising Scientist ensures the unique environment of Kakadu National Park, its Indigenous culture and its stunning wildlife are protected from the effects of uranium mining within that rehabilitation process and into the future,” he said.

“The Commonwealth view is that ERA needs to continue to make an appropriate contribution to support ongoing research during the rehabilitation phase of the mine to ensure there are no shortfalls.”