Rodney Thompson, 24, and his girlfriend were camping at Berryessa Estates near Pope Valley when they decided to go for a walk, Napa County sheriff's Capt. Tracey Stuart said this morning.
They stopped and sat down on an outcropping about a mile away, Stuart said. Thompson was sitting with his back to the water when he fell backward at about 4:30 p.m. and landed 30 feet below in about nine feet of water, Stuart said.
Thompson's girlfriend went for help and someone called 911, Stuart said. Sheriff's deputies were summoned around 4:45 p.m.
Thompson was pronounced dead at the scene, Stuart said.
His girlfriend said they had both been drinking alcohol, and drugs may also have been a factor in the fall, Stuart said.
It's unclear whether Thompson died from the fall or from drowning, Stuart said. Toxicology tests will help determine the cause of death.