Hell's Half Mile Rapid in Dinosaur National Monument/NPS file

Editor's note: This updates with the identification of the victim and correction of his age.

A 54-year-old Utah man, Michael Harp, of Sandy, on a private river trip in Dinosaur National Monument drowned when the raft he was in flipped and pinned him beneath it, the National Park Service said.

According to a release from the park, around 4 p.m. Thursday staff were notified that a boat was pinned on a rock in the rapid named Hells Half Mile on the Green River. One person from the group was missing and suspected to be pinned under the raft. The group was eventually able to unpin and secure the boat, but the person, now dislodged, unresponsive, and having lost his lifejacket, drifted downriver. 

River Patrol rangers were informed and initiated travel through the Canyon of Lodore by raft to intercept the group and conduct recovery efforts. 

At 7:45 a.m. Friday monument staff received information from Adrift, a commercial rafting company, that the victim’s body had been found and secured by guides approximately 10 river miles downstream from the location of the accident. With the assistance of Adrift guides, monument staff, and the Vernal, Utah-based Classic Air Medical helicopter crew, the victim’s body was transported to the Moffat (Colorado) County coroner. The rafter’s name will be withheld while family members are notified. 

Hells Half Mile is a class III/IV rapid located on the Green River in the Canyon of Lodore in the Colorado portion (Moffat County) of Dinosaur National Monument. It is approximately 12 river miles downstream of the Gates of Lodore [top photo] boat launch near the monument’s northern boundary. Flow rates for the Canyon of Lodore section of the Green River are influenced by the water release at Flaming Gorge Dam, which averaged 4,700 cubic feet per second from June 25-28.