No manslaughter charges will be filed against a suspected drunken boater in a fatal wakeboarding accident on Lake Sonoma this summer, prosecutors said Thursday.

Andrew Scheff, 30, of Reseda, was driving the small power boat July 24 when his friend, Brian Allan Edwards, 32, of Santa Rosa, fell off his board, suffered a head injury and died four days later.

Scheff was arrested, and the Sheriff’s Office said he had consumed about twice the legal limit of alcohol allowed while operating a boat.

But after a weekslong investigation, prosecutor Robert Maddock concluded there was no evidence that Scheff’s suspected intoxication caused Edwards’ death.

Witnesses said he wasn’t speeding or driving the boat unsafely.

It appeared Edwards hit his head on his own board after jumping in the air off the boat’s wake, an emergency responder said.

“Just because someone is driving impaired, it doesn’t mean if someone is killed it’s their fault,” Maddock said outside court.

However, Scheff was charged with misdemeanor boating under the influence and having a blood-alcohol content of more than 0.08 percent. He pleaded not guilty and was allowed to remain free on $10,000 bail. He will return Oct. 12 to set a trial date or settle the case. Scheff declined to comment after the arraignment.

You can reach Staff Writer Paul Payne at 707-568-5312 or paul.payne@pressdemocrat.com. On Twitter @ppayne.