GROVELAND — Much to the relief of businesses whose livelihood has been choked off with the closure of Highway 120 through Groveland, authorities opened the road Friday.
Highway 120 through Groveland opened at noon to all traffic, but stopping along the roadway is prohibited.
"The public is advised to use extreme caution as firefighting activities continue in this area," Yosemite National Park rangers said in a statement issued Friday. Cherry Lake Road, Evergreen Road, Old Yosemite Road, Harden Flat and all other roads and trailheads off Highway 120 remain closed.
The highway also remains closed from Crane Flat to White Wolf within the park.
The Rim fire grew overnight, climbing a spot in the chart of largest wildfires in state history. The fire, burning in Tuolumne and Mariposa counties since Aug. 17, has consumed 246,350 acres and remains 80 percent contained, the U.S. Forest Service said Friday.
Hot and dry weather accompanied by gusty south and southeast winds are expected to persist through the weekend, officials said. They expect the fire to grow more active as temperatures rise. Crews are working to secure the north flank of the fire, and are on watch for any embers that might fly over containment lines.
Roughly 3,600 firefighters remain on site, remain on site, battling the blaze that started as the result of a hunter's illegal fire.
While firefighters have gotten most of the attention, dozens of employees from the state Department of Transportation have been working hard to repair roads and help prevent the fire's spread, said Caltrans spokeswoman Angela M. DaPrato.
She provided the following facts, saying that as of Thursday, Caltrans workers have:
Replaced nearly 1,000 burned-out guardrails
Removed more than 1,800 trees that were in imminent danger of falling on or near the road
Replaced 250 reflectors and guide markers
Replaced nearly 1,000 posts
More than 40 Caltrans workers have been on the mountain since Aug. 24, working 12- to 14-hour shifts.
"In a normal day, we can replace 40 posts," DaPrato said in an email. "For the Rim fire, we have been able to replace more than 100 posts a day."
Even as firefighters battle the Rim fire, environmental scientists are moving in this weekend to begin critical work protecting habitat and waterways before the fall rainy season beings.
Members of the federal Burned Area Emergency Response team will begin hiking the rugged Sierra Nevada terrain before embers cool as they race to identify areas at the highest risk for erosion into streams, the Tuolumne River and the Hetch Hetchy Reservoir, San Francisco's famously pure water supply.
About 5 square miles of the burned area is in the watershed of the municipal reservoir serving 2.8 million people the only one in a national park.
"That's 5 square miles of watershed with very steep slopes," said Alex Janicki, the Stanislaus National Forest BAER response coordinator. "We are going to need some engineering to protect them."
So far, the water remains clear despite falling ash, and the city water utility has a six-month supply in reservoirs closer to the Bay Area.
The burned area represents 1 percent of the Hetch Hetchy watershed, said Tyrone Jue, spokesman for the San Francisco Public Utilities Commission. He said that because the sheer walls around the reservoir are granite with little vegetation, he believes that little stabilization work will need to be done.
However, initial satellite imagery and recent visits to the burned area show that the Tuolumne Canyon above the reservoir "burned pretty hot," Janicki said.
Jue said the utility will await word from the BAER team, which will be made up of hydrologists, botanists, archeologists, biologists, geologists and soil scientists from the U.S. Forest Service, Yosemite National Park, the Natural Resource Conservation and the U.S. Geological Survey.
The team also will look at potential for erosion and mudslides across the burn area, assess what's in the path and determine what most needs protecting.
The Associated Press contributed to this report.