Sheriff's Sgt. Dave Thompson said a 51-year-old Auburn woman and her boyfriend, previously believed to be her husband, were walking two pug dogs along Portuguese Beach when one of the dogs was swept into the surf.
The woman tried to save the dog and was also dragged into the surf, Thompson said. A passerby summoned State Parks rangers, Thompson said.
The boyfriend, a State Parks ranger and another person were able to get the woman back on the shore, but she had been in the cold water for about 20-25 minutes, Thompson said.
State Parks personnel gave the woman CPR before the Sonoma County sheriff's helicopter arrived but the woman was pronounced dead at the scene.
The helicopter crew used a long-line to bring the woman to the top of a nearby bluff and a chaplain responded to the scene, Thompson said.
The dog perished and washed ashore, Thompson said.
The Sonoma County coroner's office has not released the woman's identity.