Police say 61-year-old Shelby Whitaker of Brigham City was last seen on Saturday.
Investigators found tire tracks leading to a sewage pond and later discovered the truck. Officials later confirmed that Whitaker's body was found inside the truck as well.
Whitaker, who was working as part of a construction crew, did not report to work on Monday, and was reported as missing. His family and friends told authorities that his disappearance was very "out of character."
The white Ford F-250 truck with a "Whitaker Construction" logo on the side was located in one of the two ponds near a parking lot next to the construction site.
A Bannock County Sheriff's Office official said there were no signs of foul play at the scene.
The pond full of toxic material was being drained when the vehicle was found.
----Information from: KPVI-TV and CNN.