CONCRETE, Wash. -

Authorities say a man in his 50s drowned in Skagit River after he slipped while trying to retrieve his boat northeast of Seattle.
   
The Skagit Valley Herald reports the man was alone Tuesday afternoon at a boat launch near the town of Concrete when his boat started to drift away.
   
Witnesses told Skagit County Sheriff's Office deputies the man slipped into the water while trying to get the boat back.
   
A Navy helicopter crew found the man deceased about a half-mile from the boat launch.
   
The Skagit County Coroner's Office is investigating the cause of death.
   
The man's identity was not released.