Millcreek on Jul 18, 2016July 18th, 2016, 7:31 pm EDT
This is a diving beetle larvae of the Dytiscidae family. I don't know the genus or species. Got it in an area of slackwater in the Russian River. Collected on April 1, 2016. The length is approximately 25 mm.
"If we knew what it was we were doing, it would not be called research, would it?"