A Northern Territory fishing lobby group says it has concerns that pollution problems at an old gold mine near Katherine could continue if production resumes.
Vista Gold recently submitted an environmental impact statement into the possible re-opening of the Mount Todd mine.
Amateur Fishermen's Association NT (AFANT) chief executive Craig Ingram says the company needs to improve its safeguards to prevent contaminated mine water leaking into nearby rivers.
"All of the assets at the site are going to be supersized," he said.
"A vast increase in the size of tailings dams, a rock dump and the pit.
"But it appears that all of the control features, the retention ponds, will not have similar increase in size and capacity."
Mr Ingram says there is still a real risk of acidic water leaking into nearby waterways.
"Uncontrolled or controlled discharges from some of the retention ponds are still going to be a likely scenario going forward," he said.
"For us, that is unacceptable and should have been dealt with better by either increasing the capacity of the retention ponds or the pumping or other systems on site."