What might have turned into a serious environmental accident was avoided Thursday morning after a truck carrying thousands of litres of used oil crashed on a bridge over Buffalo Pound Lake near Moose Jaw.

Oil spilled out when the truck a hit guardrail and rolled around 11 p.m. CST last night, but the spill stayed on the road and didn't go into the frozen lake.

The provincial Environment Ministry was initially concerned because Buffalo Pound Lake is the source of drinking water for about 1/4 of the province, including Regina and Moose Jaw.

However, officials also said any contamination would be minimal because the drinking water intake is about 19 kilometres from the crash site.

At a briefing later in the day, officials said the oil never got in the water. A cleanup was continuing.

Hazardous materials crews and Environment Ministry staff were on the scene throughout the night. The initial police report said the driver wasn't injured. On Thursday morning, the highway was closed in both directions at the site.

According to officials, the oil that spilled came from a smaller tank that was being hauled behind the primary tanker.

They said the larger tanker had not been breached.

Work was underway to remove all the oil from the area. Getting the truck and overturned trailer out of the area was taking some time and may not get done until Friday, so the road was expected to remain closed until then.

The cause of the crash isn't known, but there was snow falling and generally poor road conditions in the area last night.