– The Ferguson fire that consumed nearly 100,000 acres of Mariposa County and shrouded spectacular Yosemite Valley for much of the summer in clouds of smoke was declared 100 percent contained Sunday.

Firefighters will continue to battle "interior islands of vegetation that will continue to ignite," but they are not a threat to containment lines, according to a U.S Forest Service statement.

"While we have reached a significant milestone, there is still more work to be done," the agency said. "Firefighters will continue to patrol, mop up and repair fire lines."

Nearly 900 firefighters continued to battle the blaze that broke out on July 13, forcing the closure of Yosemite Valley to visitors from around the world from Aug. 3 to Aug. 14.

Hwy. 41, the main access to Yosemite from the south, is expected to reopen Friday. Other park roads, with the exception of Glacier Point Road, are open.

Air quality in Yosemite was listed as "moderate," and the great granite monoliths, invisible earlier in the month, have generally emerged from hiding.

Elsewhere in Northern California, the voracious Carr fire gobbled another 8,500 acres of Shasta County overnight even as firefighters reported making significant progress toward containment.

The blaze was listed as 83 percent contained by Sunday, up from 75 percent on Friday, Cal Fire said.

"Heavy smoke over the area has continued to significantly reduce fire activity," according to Cal Fire. "Heavy timber fuels still challenge firefighting efforts."

The Carr fire, which began July 23, has killed seven people and destroyed 1,079 homes and more than 500 other structures.

The Ranch fire in Mendocino County, the largest in state history, grew another 6,000 acres and has now consumed 335,647 acres, or more than 520 square miles. Firefighters continued building containment lines and have now constructed 527 miles of border to try to stop the fire's spread, Cal Fire said.

Wildfire smoke contributed to conditions that led authorities to declare the eighth Spare the Air Day of the year in the Bay Area. Air quality was described as "moderate" for most of the Bay Area except in the Santa Clara Valley, where it was described as unhealthy for people vulnerable to airborne contaminants.