A 71-year-old Upper Lake woman spent three days lost in the Mendocino County wilderness before being discovered last week by Skunk Train staff as they passed through a secluded area closed to the public, authorities said.

The woman, whose name wasn’t released, was in an area between Camp Noyo and Northspur in Jackson Demonstration State Forest. The forest covers 48,652 acres between Fort Bragg and Willits and has an elevation between 80 and 2,200 feet.

According to the Mendocino County Sheriff’s Office, a Cal Fire official discovered the woman’s 2014 Buick SUV near the Chamberlain Creek Waterfall Trail March 17. The official identified the SUV’s registered owner and concluded it had been parked for three days.

The Sheriff’s Office was notified about 11 a.m. March 18 and search crews were mobilizing when they received an emergency alert about 12:40 p.m. They traced it to a Skunk Train railbike near Camp Noyo and found crew and visitors with the woman, who “was in good health and spirits and did not require any emergency medical care,” according to the Sheriff’s Office.

At times, the woman told [Skunk Train Guide Xochitl Villa] she thought she heard voices, only to find out it was the sound of a mosquito or a fly. Initially, she wasn’t sure if the voice she heard on Wednesday were real.

“I don’t think she had another day left in her honestly,” Villa said. “She was exhausted.”

Villa gave the woman her lunch consisting of a peanut butter and jelly sandwich, water, apples and an energy bar. Villa said the woman had intended to go on a short, thirty-minute hike to a waterfall in the area but got lost once the path became overgrown. She had no phone, her medications or other supplies and was dressed lightly in mesh-top shoes, yoga pants, a T-shirt and a thin flannel.

At night, she sheltered in hollowed out redwood stumps and buried her feet in the dirt to keep warm. The woman forced herself to stay awake, fearful she might become hypothermic in her sleep, Villa said.

“I was just in complete awe she managed to find her way out of that vast wilderness,” Villa said, adding she estimated the woman walked close to 20 miles. “If anybody’s ever traveled over Highway 20, and there’s some lookout points, it is absolutely vast, and there’s a lot of nothing out there like in any direction.”