Two spikes in contaminated water from a Northern Territory uranium mine did not breach environmental regulations because the company uses different samples as its benchmark.

Ranger uranium mine in Kakadu has plans to expand, but traditional owners are considering opposing the proposal unless the owner, Energy Resources of Australia (ERA), cleans up its practices.

There were claims last year the mine's tailings dam was leaking 100,000 litres of radioactive water into the ground below the world heritage-listed park every day.

There are renewed concerns about the mine after conservation group the Environment Centre NT this week released data showing a spike in contaminated water flowing into Kakadu's Magela Creek.

The company, majority owned by Rio Tinto, defended the spike of five times the warning level of electrical conductivity, saying it was due to salinity, and wasn't dangerous.

The Supervising Scientist Division is the authority charged with protecting the region from the effects of uranium mining, and went before a budget estimates hearing in Canberra on Wednesday.

Its head, Alan Hughes, said there was no evidence the mine was having ill-effects on Kakadu, adding ERA was working on the dam leak, and had a funded plan to clean up the site when its operation was over.

Mr Hughes said his own monitoring showed the recently revealed spikes were magnesium sulphate and no other contaminants of note.

He explained how legal contamination thresholds were based on weekly "grab" samples, even though continuous monitoring was "much more sensitive and much more effective".

"Real time monitoring has no regulatory role at this stage," he said.

While his office was trying to adopt continuous monitoring of the site and it was ERA's goal, only Northern Territory authorities could compel it to do so, and make it publish the data, Mr Hughes said.

"At the moment ERA is not required to collect continuous monitoring data," he said.

"I would assume that into the future everyone will see the value of the continuous monitoring and will probably will become the order of the day."

Australian Greens senator Scott Ludlam urged Mr Hughes to strongly encourage the company to use and publish real-time data, and expressed frustration with its regulation.

"They didn't breach any regulatory thresholds because none had been set (based on real-time monitoring)," he said. "It's hard to breach a limit if you haven't capped it."

Mr Hughes said he was reluctant to "pre-empt" the mine's commercial decisions, but agreed to raise it when they next met.

The Greens have called Ranger's track record "atrocious", claiming it has had more than 150 spills, leaks and license breaches since it opened in 1981.