A massive jet fuel spill that closed Highway 401 near Cambridge over the weekend continues to cause problems, and not only for commuters.

Clean up efforts carry on as contamination is creeping closer to Waterloo Region waterways.

On Sunday, a tanker carrying about 50,000 litres of jet fuel flipped over just before 2 a.m.

That fuel is now leaching its way into Waterloo Region.

"It's within our boundaries, our waterways, and our water supply wells," said Michael Gordon, the supervisor of environmental field services for the Region of Waterloo. "What we want to ensure that those are safe."

The Ministry of Environment is leading the clean-up.

"We are working to ensure that the owners of the spilled material are aware of their responsibilities and take the necessary steps to clean up the site to mitigate impact," said Gary Wheeler of the ministry.

The department also says environmental vacuum trucks have been deployed to absorb spilled fuel and address any fuel-contaminated soil in nearby ditches.

Containment booms are in Aberfoyle Creek along Mill Creek, including concession 2 in Puslinch Township and Gore Road in Cambridge.

Crews could not say when they would be finished here, but they did say they will be moving from bridge to bridge using absorption pads to catch the fuel travelling downstream.

"The ministry informed us that it did enter Aberfoyle Creek, which leads into Mill Creek, which does enter the Region of Waterloo," said Gordon.

The Region says they have to wait for the ministry complete its response.

There are approximately 120 water wells in the Region and the five near Shade's Mills Conservation Area have been closed as a precaution.

The ministry of environment says the fuel has not entered the conservation area.