Crews are back at work on the North Saskatchewan River trying to recover oil and other contaminants after high water interrupted the Husky Energy spill clean-up.

Heavy rains pushed the water levels up, but they have now receded and stabilized, said provincial government officials in an update today.

"181 cubic metres of oil have been recovered to date. This is close to 80 per cent of the total estimated oil that was released," said Wes Kotyk with the province's Environmental Protection Branch.

About 250,000 litres of oil spilled when a Husky Energy pipeline sprung a leak back in July.

The clean-up crews face some new challenges as the recent high water flows created new silt deposits and riverbank erosion. That appears to have moved around, or covered up some identified contamination hot spots.

Recovery work is expected to continue for the remainder of September and possibly into October depending on weather conditions, officials said.

Questions remain unanswered

Even as the clean-up effort goes on, some big question about the spill remain.

First, what caused the pipeline to leak?

"We are not prepared to speculate," said Laurie Pushor with the Ministry of the Economy.

"We are doing a thorough and comprehensive investigation, analyzing all areas of interest and we'll do a full comprehensive review and it will be fully and completely released when it's completed," he said.

Drinking water risk potential unknown

Also of concern to thousands of people, when will affected communities be able to begin drawing drinking water from the North Saskatchewan River?

Test results are encouraging, but it's more complicated than that, according to Sam Ferris with the Water Security Agency.

"Because this is a turbid river, it's muddy in appearance from time to time and it's likely that remaining oil is going to be attached to turbidity or suspended sediments, so we need to understand what those risks are in terms of potential health impacts," said Ferris.

How long it will take for officials to understand the risks will take some time, but exactly how long, Ferris really couldn't say.

Some of the temporary solutions to drinking water supplies issues involve above ground pipes. Those make-shift systems are working for now, but will not continue to flow in winter. Ferris thinks he'll have all the answers he needs before freeze up

"I'm fairly confident, yes."