(Gresham, OR)  --  The Multnomah County Sheriff's Office is releasing new information about a man who drowned in the Sandy River near Oxbow Park on Wednesday.  Witnesses say 46-year-old Derek Johnson, of Portland, was stand-up paddling when he fell into the river and didn't resurface.  His cause of death was ruled a drowning.  Johnson wasn't wearing a lifejacket.