The lead Commonwealth regulator with oversight of the Ranger Uranium mine has acknowledged that real time water monitoring is the best way to test contamination of waterways downstream of the Ranger Uranium Mine.

After questioning from Australian Greens Senator Scott Ludlam at Senate estimates in Canberra today, Supervising Scientist Alan Hughes said that his Office had spent several years perfecting techniques for real time water sampling, and that the company had also begun such monitoring.

"It is time the Supervising Scientist stepped in to make sure that real time water quality data is made public by the company so that we can all be confident that events like this don't ever go under the radar," Senator Ludlam said.

Mr Hughes has promised to advocate for this at forthcoming meetings with ERA other stakeholders - we await confirmation that this entirely reasonable commitment is met.

"The recent contamination spike into the Magela Creek system in Kakadu wasn't picked up by the routine 'grab' monitoring that downstream communities rely on.

"Mr Hughes said the recent contamination spike at Magela Creek didn't breach any regulatory thresholds, but then acknowledged that none had been set.

It's hard to breach a limit if you haven't capped it," Senator Ludlam said.