The man was found by a bicyclist on Zone 7 property known as the Alamo Canal, not far from Johnson Drive; police do not believe foul play was involved.
The bicyclist called police after finding the man, in his late 30s or early 40s, lying dead in a sleeping bag.
The man has been identified by the Alameda County Coroner's Office, but his name and the cause of death are being withheld until his family can be notified.
The bicyclist who found the body told police he had seen the same person, alive, about one week ago.
The man was found in an area that appears to be a homeless encampment. The site is not far from the Pleasanton Hilton Hotel and ClubSport, across Johnson Drive.
A sleeping bag, blankets, coolers, bicycle, guitar, clothing and camping gear are scattered though the area, directly below the highway. Cars and trucks rumble overhead and graffiti marks nearly every flat surface. A bag of garbage lies nearby, along with empty food containers and liquor bottles.
The man is the second homeless person found dead in Pleasanton this year. In February, the body of a man was found down a railroad easement near Case and Valley avenues.
An autopsy in that case ruled there was no foul play. As in the current case, the identity was withheld because the family had not been notified. In that case, police conjectured the man may have been walking toward an encampment somewhere in the area while returning from Raley's on Sunol Boulevard.
Anyone with information that could help in the investigation into the current case is asked to contact the Pleasanton Police Department at 931-5100.