Vacuum trucks and absorbent pads are soaking up the remaining oil Wednesday night were 7 acre were contaminated Monday.
An 8 inch pipe broke leaking the oil into the water.
Chevron officials say they reacted to the spill within minutes and prevented the spill from spreading into a larger area.
"We've located the source (of the leak). The site of the line where it's leaking," said Chevron's Vice President for the mid continent pipeline, Terry Duhon.
Workers are confident the leak is sealed. However, questions about what caused the leak remain unanswered. "We need some time to be able to investigate it to understand what caused this incident," said Duhon.
The 50-year-old pipe transports diesel from Salt Lake City to Burley, Idaho and eventually on to Washington State.
This is Chevron's third oil spill in Utah in less than three years. The first two were along the Red Butte Creek in 2010 and 2012.
"Our goal is to ensure that this leak has been stopped and we're confident that it has, that the material is not going into Willard Bay Reservoir quickly clean area that has been contaminated," said Environmental Protection Agency spokesman, Curtis Kimbel.
The cleanup effort is now focusing on areas where the oil could be caught on rocks, grass or other areas.
Two unsuspecting hero's are beavers who are recovering at a Wildlife Rehabilitation Center in Ogden. Their dam prevented the oil from spreading into a larger area.
The EPA penalized Chevron $3.5 million for oil spills along the Red Butte Creek in 2010 and 2012. The EPA will take these spills into consideration when it hands down a penalty for the Willard Bay spill.