(Multnomah County, OR)  --  Multnomah County sheriff's deputies are investigating, after a man drowned while swimming at Rooster Rock State Park.  Authorities say the man, who was in his 50s, went under the water around five p.m. yesterday, and emergency crews were called in after he didn't resurface.  The man's body was recovered by a dive crew around eight o'clock last night.  His name hasn't been released.