The Alberta government has ordered Coal Valley Resources and Sherritt International to clean up a massive spill of coal mine wastewater in the Athabasca River.

On Oct. 31, Sherritt International's Obed Mountain coal mine spilled about 1 billion litres of contaminated water into the river.

Test results released by the Alberta government show there is no immediate risk to human health for communities along the river with water treatment plants, but the province says long-term health impacts are still being evaluated.

Helicopter monitoring shows the 150-kilometre sediment plume is now about 178 kilometres south of Fort McMurray.

"The water quality guidelines were exceeded in some areas," said Jessica Potter, a spokesperson for the Alberta government.

It says those areas were within 40 kilometres downstream of the location of the spill. The Alberta government says its results found that after moving downstream, the chemicals did dilute.

Among the contaminants found were aluminum, manganese, lead, cadmium, mercury and cancer-causing compounds.

The Alberta government's test result summary says, as a precaution, community water treatment plants should continue not to use the Athabasca River when the plume is near. Individuals that use the Athabasca River as their drinking source or for their livestock should find alternative sources when the plume is in their area. 

The province is also reminding people not to drink untreated river water regardless of the location of the sediment plume.

Some First Nations leaders say they should have been told earlier about the spill and they worry about future health impacts such as cancer.

"Everybody is still going to drink that water," said Allan Adam, chief of the Athabasca Chipewyan First Nation. "This is our Safeway, our Extra Foods, our Sobey's. Everything we have is on that land."

Leaders from the Northwest Territories say they're losing trust in the Alberta government. Water from the Athabasca River flows into the Slave River and eventually into N.W.T.'s Great Slave Lake.

"The Alberta government has taken this thing very lightly," said Sam Gargan, who co-chairs of Keepers of the Athabasca.

"They have only been able to respond to the breakdown of the chemicals once it was brought to the world." 

Gargan says if people get sick from the coal mine's wastewater, it's not clear who is responsible.

Sherritt International said it has received the environmental protection order and will continue water monitoring.