Ferguson Fire grows to 21,000 acres. Yosemite visitors warned of poor air quality

The Ferguson Fire roaring through Mariposa County has grown to 21,041 acres, Cal Fire reported Thursday, and containment was at only 7 percent.

Yosemite National Park remained open, but the park announced via Instagram that Glacier Point Road would be closed at 10 p.m. Thursday and it’s unclear when it will reopen.

“Firefighting resources and activities involved in the nearby Ferguson Fire have necessitated the need for a small base camp located at the Yosemite Ski and Snowboard Area (formerly Badger Pass) and Bridalveil Creek Campground (which is also closed),” read a portion of the post.

The fire, which has been burning west of Yosemite National Park since the evening of July 13, has also caused a decline in Yosemite’s air quality.

Cassandra Melching, spokesperson for the San Joaquin Valley Air Pollution Control District, said the Valley air quality for most areas was at a level 3 Thursday, with the worst being level 5 closer to the fire. She said the bad air quality could present problems for people with respiratory problems.

Melching said the air quality is extremely poor closer to the blaze that was sparked off Highway 140 near El Portal. “They’re definitely going to want to remain indoors,” said Melching, referring to people in Yosemite.

Yosemite’s air quality readings ranged between level 3 and level 5 on Thursday.

Yosemite National Park echoed Melching’s sentiment via its Instagram account: “Move activities indoors or reschedule to a time when the air quality is better. Everyone else should reduce prolonged or heavy exertion and take more breaks during all outdoor activities.”

Fire crews were working around Jerseydale along Sweetwater Ridge and trying to complete containment along Highway 140 at Cold Canyon. No structures have been damaged or destroyed.

A Cal Fire spokesman said crews are continuing to build indirect lines along Sweetwater Ridge and from 140 to Wawona Road, the continuation of Highway 41 in Yosemite National Park. Helicopters were able to drop water retardant in the Sweetwater Ridge area Thursday afternoon.

“We are making progress in those areas,” said Michael Whitaker, a spokesman for Cal Fire.

Structures along the Jerseydale and El Portal areas are the most threatened, said Whitaker. A mandatory evacuation order was given Thursday afternoon to the residents of the El Portal Trailer Court.

Whitaker added that the firefighters hope to keep the fire south of Highway 140.

The possibility of thunderstorms was expected to increase Thursday, which could cause erratic winds that may change the direction of the fire, an additional hazard for firefighters.

Thunderstorms did not materialize during the afternoon, but the smokey conditions did make it impossible for water tankers to take to the air.

Total personnel grew from 1,850 to 2,149 Wednesday night, and Whitaker said that number could continue to grow. As of Wednesday, there were 166 engines, 21 water tenders, 18 helicopters, 55 hand crews and 29 bulldozers assigned to the fire.

Firefighters are also fighting a 40-acre fire in Mariposa County off of Ben Hur Road, Cal Fire reported.

This story was originally published July 19, 2018 at 7:55 AM with the headline "Ferguson Fire grows to 21,000 acres. Yosemite visitors warned of poor air quality."