An environmental scientist is calling on a uranium miner in Kakadu National Park to urgently improve its water management or it risks serious harm to the environment.

Energy Resources of Australia (ERA) suspended operations at the Ranger uranium mine processing plant earlier this year because of concerns the toxic tailings dam was almost at capacity.

ERA has now announced it is commissioning an $80 million study into the feasibility of building a brine concentrator to separate dangerous substances from the water.

Dr Gavin Mudd from Monash University in Melbourne says the research will delay any decision to go ahead and build the concentrator.

"It is still in the future," he said. "It is still a year away or more and that is not good enough."

ERA chief executive Rob Atkinson says the study is essential.

"If we are being pragmatic about it, it is a very large investment," Mr Atkinson said.

"The concentrator would cost about $220 million."