An arborist was discovered dead in a tree on Camp Mather land near the Hetch Hetchy entrance to Yosemite National Park on Wednesday last week, according to Tuolumne County Sheriff’s Office staff.

The man was identified last Friday evening as Alfred Salas, 50, of Vallejo. A spokesperson for the Tuolumne County Sheriff’s Office said Salas appeared to suffer some kind of medical emergency before he died. An autopsy will be performed to determine the cause of death.

A Yosemite National Park ranger was the on-scene contact for the Tuolumne County coroner.

The state Division of Occupational Safety and Health, better known as Cal/OSHA, was notified the same day Salas was found deceased.

Frank Polizzi, a spokesperson for the California Department of Industrial Relations, said Monday an employee of San Francisco Parks and Recreation “suffered a medical incident such as a seizure or heart attack while trimming a tree.”

Cal/OSHA is investigating to determine exactly what occurred, Polizzi said, and if there were any violations of workplace safety regulations.

Camp Mather is 337.5 acres owned and operated by the City of San Francisco Recreation & Park Department. It’s private property within the Stanislaus National Forest footprint, a Forest Service spokesperson said. Camp Mather is also part of Tuolumne County.

Sheriff’s logs show an ambulance call at 3:24 p.m. Sept. 18 with notes including “Occurred at Camp Mather on Mather Rd” and “Arborist unconscious in a tree” and “Disposition: Coroners Call.”

Yosemite park rangers and an ambulance crew were en route, and there was a request for Tuolumne County to start sending people, too. Sgt. Andrea Benson with the Tuolumne County Sheriff’s Office said Friday afternoon she would check if notification had been made to next of kin.

Scott Gediman, a public affairs officer in Yosemite, said Friday that federal rangers from Yosemite responded because of a cooperative agreement with Tuolumne County. Gediman said the location was outside park boundaries and he would not release specifics about the incident.

Approached Friday with questions about the Wednesday incident, the press office for the Mayor and City of San Francisco asked The Union Democrat for more information about what happened at Camp Mather.

Diana Fredlund with Stanislaus National Forest said she checked with Forest Service dispatch and they knew about the call because they heard it over the scanner. The Tuolumne County Sheriff’s Office did not request any assistance from the Forest Service, so the Forest Service did not go out there to help on the call.

A recorded message Friday at Camp Mather General Store said Camp Mather is closed for the season and reopening is expected around the end of May 2020.

Bark beetle infestation in recent years hit thousands of trees at Camp Mather, just like it did across much the Central Sierra, parts of Yosemite National Park, and the Stanislaus National Forest.

By May 2017 the San Francisco Recreation & Park Department had hired contractors with Groveland-based Crook Logging to remove more than 1,500 trees from Camp Mather. It was a $1.6 million project. A representative for Crook Logging said Friday the company had no knowledge of the Wednesday incident.

Before Europeans and their descendants came to California, the area that includes Camp Mather was home to MiWok people and other Native Americans who gathered acorns there.

In the late 1800s ranchers acquired land in the Hetch Hetchy area to graze cattle and sheep. Then authorities and promoters with the City of San Francisco, enabled by U.S. Congress and the Raker Act of 1913, began building their dam and reservoir on the Tuolumne River in Hetch Hetchy Valley. Construction camps were erected and a sawmill was built near Mather to supply lumber for the dam's construction.

In the 1910s and 1920s, a concession predecessor of Yosemite Park and Curry Company leased the dining side of Camp Mather as a resort for tourists, and built the Hetch Hetchy Lodge building, now renamed Jack Spring Dining Hall, which serves today as the Camp Mather kitchen and dining room.

O’Shaughnessy Dam was completed at Hetch Hetchy in 1923. Families from San Francisco began using Camp Mather for summer recreation in 1924. San Francisco residents began using Hetch Hetchy water in 1934. The City of San Francisco Recreation & Park Department still owns and operates Camp Mather to this day.

Contact Guy McCarthy at or 588-4585. Follow him on Twitter at @GuyMcCarthy.