Dene leaders are demanding the provincial and federal government do more to protect the territory's waters from development projects in Alberta.

More than 120 people gathered in Yellowknife last night to voice concerns about the berm break at Sherritt International's Obed Mountain coal mine near Hinton, Alta. nearly a month ago. The Dene Nation organized the forum; chiefs from the Tlicho, the Dehcho and the South Slave attended.

Officials from Sherritt International were also at the meeting. Both the company and the Alberta government say the 670 million litres of wastewater won’t affect drinking water in the Northwest Territories.

Sean McCaughan

Sean McCaughan, vice president of Sherritt International: 'There is no impact on public health.' (CBC)

"Our results that are still coming in are showing that same message,” said Sean McCaughan, vice president of Sherritt International. “That water quality is within drinking water guidelines and our risk assessment, our human risk assessment, our water quality assessment show there is no impact on public health.”

Company officials told the crowd the majority of the clay, shale and coal dust has settled on the river bed within 40 km of the spill site, but McCaughan admitted the sediment will become harder to track as it travels north.

“We have an investigation under way to find out what happened,” McCaughan said. “This incident is something that we’re gonna get to the bottom of, we’re going to find out the reasons for it, and we’re going to make sure this doesn’t happen again.”

The Northwest Territory's chief public health officer was at the meeting. He said the territory's drinking water is not and will not be at risk.

Dr. Andre Corriveau also spoke to concerns about contaminants moving up the food chain.

He said plenty of data has been collected on this in the last 20 years, providing a good baseline, and called for long-term monitoring to track contaminants in fish and wildlife. “This is not something that happens overnight. It’s something that happens over a number of years.”

But that didn’t ease concerns.

"It looks like it's going to be diluted in Lake Athabasca,” said Dettah Chief Eddie Sangris. “The cumulative effects will reach further down."

And Sangris wasn’t alone in his concern. Dene elder Francois Paulette also spoke at the meeting.

Sam Gargan

Sam Gargan of Keepers of the Athabasca: 'The more you dump into the water, the more you damage the water.' (CBC)

“I have more concern about the fish that are in the river, that feed when the water is low and they can’t find the little streams to go up where there’s much clearer water, but they gotta stick to the river,” Paulette said. “I have a big, huge concern about that.”

Sam Gargan chairs Keepers of the Athabasca, a collection of First Nations, Metis, Inuit and environmental groups that works to protect the Athabasca River watershed.

“I would ask if there was ever a contingency plan,” Gargan said, “because if you know anything about contaminants, what does culmulative effect mean? The more you dump into the water, the more you damage the water.”

Gargan says oil sand developments and pulp mills also pose a threat.

The forum ran for four hours.

For now, Sherritt and the Alberta government will continue to monitor the waste water as it travels north. It's still about 500 kilometres from the territory's border.

The Alberta government's next water quality report is set to be released on Wednesday, Nov. 27.