The spill was discovered Tuesday about 10 kilometres east of Red Deer on a line belonging to Penn West Exploration (TSX:PWT).
The Calgary-based company estimates up to 300,000 litres of liquid pooled up from a leak in an injection line.
The spill is mostly produced water — an industry term for the water which travels up well heads along with oil. It can contain high levels of salt.
Penn West Spokesman Greg Moffatt said Thursday initial tests show the fluid is almost 99 per cent produced water with low levels of salt and about one per cent oil.
"It's more of a water spill than an oil spill," he said. "Not to downplay the impact on the soil in the field, but it is a very, very low chloride water, so the impact should be minimal."
Darin Barter of Alberta's Energy Resources Conservation Board said he can't confirm the size of the spill until the agency's investigation is complete. But licencing documents show the line was carrying produced water containing three per cent oil.
"The water isn't fresh water. It's not something you want on a field," Barter said. "That's why we're certainly encouraging Penn West, and overseeing the clean-up, to get it off the ground as quickly as possible."
Moffatt said he's not sure if the farmer will be able to harvest the crop. There will be compensation for any damage both from the spill and the company's clean-up efforts.
He said operators noticed a drop in pressure on the 10-centimetre line Tuesday. A helicopter did an aerial survey of the line but was unable to find the location of the spill, so staff were dispatched to look for it on foot.
The fluid covered about 6,000 square metres of land, Moffatt said, adding the farmer helped swath a path through the field for the clean-up crew.
Vacuum trucks collected about a third of the estimated fluid on Wednesday, Moffat said.
He expects the clean-up will continue for another two days before workers can uncover the line and investigate the cause of the leak.
— By Chris Purdy in Edmonton