A pipeline in western Canada has leaked crude oil into a local river, its operator said Tuesday amid fears the drinking water supply of 90,000 people could become contaminated.

The 50-year-old Rangeland Pipeline gave way Thursday night, releasing between 1,000 and 3,000 barrels (160,000 to 480,000 liters) into a tributary of the Red Deer river in Alberta province, Plains Midstream Canada said.

The flow of oil through the pipeline was cut upon discovery of the leak and a crew of more than 180 people has been deployed to clean up the contaminated sections of the waterway, it added.

Still, fears have spread that the drinking water supply of the city of Red Deer, which has a population of 90,000 and is located 100 kilometers (62 miles) from the slick, could become contaminated if the oil seeped into the Red Deer river.

In an attempt to allay concerns, Plains Midstream said water quality was being tested twice a day at 18 different sections of the affected area and that the strong smell of oil did not pose a health risk.

In addition, bottled water had been delivered to hotels in the area, according to company official Stephen Bart.

Meanwhile, Greenpeace warned that the Canadian government was not doing enough to stop such environmental hazards from happening.

"Once again we have a major spill go unnoticed by a pipeline company, this time flowing directly into a major waterway," said Mike Hudema, a Greenpeace climate and energy campaigner.

The leak occurred as Plains Midstream Canada was cleaning up the remnants of another leak dating back to April 2011. At that time, 4.5 million liters (1.2 million gallons) were released into the Peace River.