Big Horn County Coroner Terry Bullis identified the man whose body was found dead north of Hardin on Sunday as Maynard Kenneth Hill, 61, of St. Xavier.
Hill's decomposing body turned up Sunday afternoon 17 miles north of Hardin, according to an email from the sheriff's office.
Bullis said it appears that the man drowned, but the official cause of death remains to be determined.
He said authorities are still investigating how Hill ended up in the river.
The body was found near Sunlight Ranch by a ranch hand, about three-fourths of a mile off a dirt road on a river rock bed, according to Undersheriff Michael Fuss.