The pipeline break that belched almost half a million litres of sulphur-rich crude oil into southern Alberta's Red Deer River could take until the end of the summer to clean up, CBC News reported.
And some of the oil has washed into the Gleniffer reservoir, the source of drinking water for thousands of area residents.
So far officials have not issued boil-water or drinking water advisories for the city of Red Deer and adjacent counties, CBC said, but the province is monitoring water as well as air quality.
"Below the boom containment, (water) meets Canadian drinking water standards," said Alberta Environment spokesperson Jessica Potter on Sunday about some initial results that were sent to the lab. "Those are first results, so that's a really good sign."
Pipeline owner Plains Midstream Canada has said the spill is largely contained but water from north of the town of Sundre to the reservoir is not to be used for drinking, officials warn. The company has been trucking in water for local residents.
Even with the expected cleanup, residents of the picturesque farming and ranching area worry about the long-term impact of the spill.
The Johnson family, which farms near Sundre, has gone through three pipeline breaks in the last two decades - one in 1994, another in 2008 and now this one. A pipeline on her property also experienced three breaks last year between September and December.
Ila Johnson was gardening Friday when she detected a "horrible smell" that kept getting stronger.
"I decided to go to the hospital because I just couldn't catch my breath," she told CBC News.
Johnson said the family's farm now can't produce food and the downstream effects on the reservoir, a popular fishing and boating spot, are uncertain.
Plains Midstream vice-president Stephen Bart claimed the fact oil wasn't being pumped through the line at the time of the break, plus high water levels in the river that washed oil into the reservoir where it could be more easily contained reduced the spill's potential impact.
But fishing guides and local residents worry it's done long-term damage to one of Alberta's top sport-fishing destinations. They want long-term monitoring.
"They've got to be here for as long as it takes to monitor what's going on along that river, for sure," guide Garry Pierce of Tailwater Drifters told The Canadian Press.
"I just hope they're not going to come in for three weeks or a month and say 'Oh yeah, we're good. We've got it cleaned up, and off we go.' That's just not going to be good enough."
Meanwhile, the incident is being closely watched across the border in British Columbia, where two proposed oil sands export pipelines to the west coast are being hotly debated.
"The oil-pipeline spill into the Red Deer River will no doubt further damage Enbridge's arguments in favour of its proposed Northern Gateway project, which would see an oil pipeline run from Alberta to B.C.'s northern coast," political commentator Keith Baldrey wrote Tuesday in Surrey Now.
"However, it's less certain whether the other proposed pipeline - Kinder Morgan's plan to 'twin' its existing pipeline from Edmonton through Burnaby (near Vancouver) - will suffer a similar backlash."
The Kinder Morgan line is less controversial because it follows the company's existing 60-year-old pipeline right-of-way, despite a catastrophic break in the line a few years ago when a construction crew pierced it.
"The Enbridge pipeline, however, would cross more than 600 rivers and would be located in vast tracts of pristine wilderness that have never experienced industrial development in their ecosystems," Baldrey wrote.
"Contrasting the Red Deer oil spill, which fouled kilometres of shoreline and may threaten the drinking water for 100,000 people, to something similar happening on, say, the Skeena River is going to make many people very, very nervous."
Pipeline breaks are rare events, Baldrey observed, but images from one serious spill can have a major public-relations effect.
The political debate over the pipeline projects has yet to really gel in B.C. but Baldrey, who covers the legislature for Global TV, said pictures from the Red Deer River spill will likely harden opposition to Northern Gateway, he said.
"Pipeline politics continue to heat up in this province, and the timing of that spill couldn't be worse for a company already in the crosshairs of a huge campaign to discredit its entire project."