Canada is facing a September 28 deadline from the NAFTA-mandated Commission for Environmental Co-operation (CEC) to explain why it has allegedly permitted tar sands/oil sands producers to dump up to 11 million litres per day of toxic benzene, arsenic, and cyanide into the Athabasca River in northern Alberta.

The original complaint to the Montreal-based commission, which oversees the environmental side agreement under the NAFTA accord, was lodged in June by Environmental Defence and the U.S. Natural Resources Defense Council.

The deadline is for Canada’s response to the groups’ allegations that “it is failing to enforce the Fisheries Act by allowing contaminants from the ponds to leak into water without forcing the companies involved to fix the problem,” Canadian Press reports. “The request for a response from Canada means the commission found the complaint was submitted by legitimate organizations which offered science-based evidence for their complaints,” the news agency adds, “and that it was intended to promote enforcement of environmental law rather than simply harass industry.”

“They’re saying, based on the evidence presented to them and their legal review, it looks like the Canadian government isn’t enforcing the Fisheries Act and they want to know what the Canadian government thinks about that,” said Environmental Defence Executive Director Tim Gray. He added that the record of the CEC’s review could be used as a court document, should the groups decide to sue the federal government to enforce its own laws.

Environment and Climate Minister Catherine McKenna’s spokesperson, Marie-Pascale Des Rosiers, told CP the government expects the complaint to be resolved soon. “Our government takes the protection of water very seriously,” she wrote in an email. “We are proud of our world-class, joint oilsands monitoring system we have with the government of Alberta.”