The operator of the Ranger Uranium Mine says a 12-week production shutdown has seriously affected the mine's business performance.

A heavy wet season led the mine, which is next to Kakadu National Park, to suspend production at the end of January to avoid polluted water running into nearby waterways.

Energy Resources of Australia's chief executive Rob Atkinson says the mine's tailings dam still has capacity for more water, and it is unlikely the company will need to divert water into its active mining pit.

Mr Atkinson says the mine has brought forward maintenance work and made good use of the production shutdown, but the decision has still hurt.

"The biggest hit of all is when you've got 12 weeks of no production, you've obviously got no sales and obviously little revenue," he said.

"That does impact you and that's where the biggest impact to our business has been, so it has been a substantial impact to our business."