A Coast Guard team rescued a woman suffering from hypothermia and floating adrift on a life ring in the delta's San Joaquin River on Monday after getting reports she fell off her houseboat, officials said.
Investigators were working Tuesday to figure out how the woman, who was not identified, became stranded on the flotation device in the remote area of the Sacramento-San Joaquin River Delta.
A person, though, had reported the woman may have fallen off a houseboat into the water, Coast Guard officials said.
The rescue began around 5:15 p.m. Monday when someone spotted the woman bobbing in the water near Rivers Edge Marina at Sevenmile Slough and calling for help, officials said Tuesday.
Rescuers aboard a boat scrambled to the area where the woman was last spotted in the waning daylight. Once on scene, the team followed cries for help and found the woman floating on the river, clinging to a life ring.
The Coast Guard pulled the woman onto the boat and brought her to Rivers Edge Marina, where she was treated by paramedics and taken to a hospital. The woman was showing signs of hypothermia when she was pulled out of the water, Coast Guard officials said.
Her condition was not immediately known.
"Because the incident occurred at sunset, there was less daylight, making it more challenging to locate her in the dark," Petty Officer Second Class Mandy Braasch, said in a statement.
She added, "In this situation, the woman had a life ring, which significantly contributed to her survival and rescue."
The Coast Guard was investigating how the woman ended up in the water.