The federal government is being urged to heed the advice of its experts and reject a bid to release coal seam gas wastewater into a Queensland river.
Santos has applied to release untreated wastewater from its central Queensland gas fields into the Dawson River during floods.
It's a tributary of the Fitzroy River, which flows into the Great Barrier Reef, and a habitat for critically endangered white-throated snapping turtles and threatened Fitzroy River turtle.
The Commonwealth ruled on July 16 that Santos' Fairview proposal had to be a controlled activity, and referred it to an independent scientific panel.
Two weeks later the panel advised the federal government to reject the company's proposal, but advice is still being held by the government which is yet to make a decision.
"Untreated produced CSG water should not be released into any surface waters, even during high flows, because of the risks of short- and long-term impacts of mixtures of chemical contaminants on downstream aquatic, riparian and shallow subterranean ecosystems," said the panel's yet-to-be released advice, seen by AAP.
"Downstream legacy impacts of some of these contaminants are unlikely to be resolved merely by dilution, especially as the releases of untreated water are projected to potentially continue until 2066."
Lock the Gate Alliance has called on Environment Minister Tanya Plibersek to reject the proposal.
The group said the Santos application was a "lazy and ill-considered" plan which threatened habitats and endangered species.
"This is an opportunity to put threatened species first," spokesperson Ellie Smith said in a statement.
"Minister Plibersek should refuse this risky wastewater proposal and save some of the last remaining populations of white-throated snapping turtles."
The panel said it was "very concerned" about the risks the project posed to a population of white-throated snapping turtles at the site.
It said the turtles are isolated from other downstream populations, and untreated water releases could potentially reduce their population or their ability to reproduce.
"There is a high chance that the population at the project site will become locally extinct as the downstream population will not be able to access and repopulate the area," the panel wrote.
"The IESC (Independent Expert Scientific Committee on Coal Seam Gas and Large Coal Mining Development) is very concerned about the risks of this project, especially the potential long-term impacts of event-based releases of untreated produced water, on the persistence of this critically endangered species."
The report said releasing untreated coal seam gas drilling water containing chemicals could pose a risk to the ecosystem.
However, Santos hadn't provided details about the concentration of chemicals it proposed to release in its risk assessment.
"Their potential impact cannot be determined," the panel wrote.
Wildlife Preservation Society of Queensland Upper Dawson member Ann Hobson said Santos should not discharge its wastewater into the Dawson or its catchments.
She said native species and people living downstream depended on the "life-giving" river.
"The turtles and the aquatic life that depend on the health of this river need our help," Ms Hobson said.
"They must not be sacrificed so Santos can make more money shipping gas offshore."
