Plains Midstream held an information session on the progress of its cleanup near Sundre, Alta., on Saturday. (Kyle Bakx/CBC)

After months of an extensive clean-up, Plains Midstream says its job is finally complete.

The pipeline company was responsible for an oil spill several months ago when an estimated 3,000 barrels of oil flowed into the Red Deer River near Sundre, Alta.

Stephen Bart, with Plains Midstream, says the cause of the pipeline burst remains unknown.

“It wasn’t until the middle of August that the actual damaged area of the pipe was able to be moved safely from the river itself so that pipe has been taken by regulators and is undergoing an array of metallurgical and forensic testing to understand the failure mechanism in place,” Bart said.

“Obviously we like this not to happen, we regret the incident, but we're delighted at how effective the cleanup has been so far.”

The company has packed up the majority of equipment and most of the workers have left the site.

Next year, further restoration work will continue in the area.

Many people who attended an open house on Saturday say they were pleased with the cleanup.

"This one kind of blew me away,” John McBeath said. “Actually polishing rocks along the river banks — I didn't know they did that, so that somewhat impressed me."

But others worry about future pipe breaks.

"These pipelines and everything, they are getting aged, same as we are,” Len Duquay said. “I think everyone fully expects it will happen again somewhere, but who knows when."