Contaminated water that leaked from an oilfield pipeline on Christmas Day has entered the North Saskatchewan River but has had no detectable impact on it, says a spokesman for Calgary-based oil and gas producer ARC Resources Ltd. The spill was reported by a local landowner at about 2 p.m. last Friday, said Sean Calder, ARC's vice-president of production, in an interview on Tuesday. "We had guys on site within about an hour and then the pipeline was shut in by 4 p.m., I believe," he said.