The Commonwealth supervising scientist of the Ranger uranium mine at Kakadu National Park says investigations are continuing into water contamination at the site.

Alan Hughes has told a Senate estimates committee that Energy Resources of Australia has conducted geophysical surveys to determine the impact and extent of leaking from a tailings dam at the mine.

Mr Hughes says the company has only preliminary results from the surveys and is not sure if ERA will make the findings public.

"I understand that they are having significant discussions with the traditional owners and the Northern Land Council about tailings and seepage issues on an ongoing basis," he said.

"So I imagine all the immediate stakeholders will be very well informed on the issue."

Greens Senator Scott Ludlam is demanding the report be made public as soon as possible.

"We don't think those sort of reports should be internal," Senator Ludlam said. "We think that should clearly be in the public domain.

"If the company has any further results or information or monitoring results, we certainly think they should be released when they are ready."