EDMONTON — Two companies have been charged over a huge 2013 spill from a coal tailings pond that fouled tributaries feeding the Athabasca River.

Coal Valley Resources Inc. and Sherritt International Corporation (TSX:S) face six charges under Alberta's Environmental Protection Act, Public Lands Act and Water Act.

The charges follow a spill of about 670 million litres of waste water that gushed out of a broken earth berm at the Obed Mountain mine near Hinton on Oct. 31, 2013.

The Alberta Energy Regulator said at the time of the spill, Coal Valley operated the mine as a subsidiary of Sherritt.

The regulator said material in the spill included minerals, bits of coal and a substance used in coal production. Groups citing data from Environment Canada's National Pollutant Release Inventory have said that toxic compounds such as arsenic, mercury and cadmium were being dumped into the ponds in years prior to the spill.

In the weeks following the spill, the province advised downstream communities not to draw water from the river and farmers not to let livestock drink from it. Two tributaries of the Athabasca River were affected.

Sherritt said it was reviewing the charges.

"The release at Obed Mountain was an unfortunate occurrence, but does not reflect on Sherritt's commitment to operational and environmental safety," Mark Sitter, a company spokesman, said in an email.

"Since the release, we have worked collaboratively with provincial and federal regulatory authorities throughout the investigation into this matter and have begun discussions on next steps in this process."

A draft report prepared for Sherritt by Millenium EMS Solutions Ltd. on the spill earlier this year concluded that it did not pose a threat to human health.

"Overall, there is no expectation of adverse effects on human health based on chemical exposure arising from the October 2013 release," reads the report posted on a Sherritt website.

Sherritt said it is committed to understanding the circumstances that contributed to the release and is taking the steps necessary to prevent any recurrence.

"I'm happy they're facing six charges," said Bruce Maclean, who helps First Nations in Fort Chipewyan operate an environmental monitoring program.

"There's a lot of concerns in the community related to wild food health."

Brittany Verbeek of the Alberta Wilderness Association also welcomed the news.

"After waiting almost two years, we were pleased they are pressing charges," she said.

However, she called on federal prosecutors to lay charges under the federal Fisheries Act. She also said there remain unanswered questions about the Obed spill.

"There's lots of questions about whether there were issues prior to the spill," she said.

The maximum combined fine for all six charges is just over $2 million, said Fraser Thomson, a lawyer for Ecojustice. That's not enough, he said.

"If the government is going to get serious about preventing these kinds of occurrences, they need to look at increasing those maximums."

Thomson said Environment Canada said as late as Sept. 25 they were still investigating the spill.

The companies are to appear in Hinton provincial court on the charges on Jan. 20.

Bob Weber and John Cotter, The Canadian Press