Wildfire grows to California's fourth largest as crews make progress Sun Sep 1, 2013 8:29pm EDT (Reuters) - A large California wildfire that has blackened a swath of Yosemite National Park backcountry grew to the fourth largest in modern state history even as fire crews managed to slow the spread of the flames over the weekend, officials said on Sunday. The Rim Fire had charred nearly 223,000 acres by Sunday, mostly in the Stanislaus National Forest that spreads out from Yosemite's western edge. The blaze has blackened about 6 percent of Yosemite's wilder backcountry. It edged past the 1932 Matilija wildfire in Ventura County to become the fourth-largest California wildfire on record, according to figures from the California Department of Forestry and Fire Protection. Five of the state's seven largest fires in recorded history have occurred since 2007, according to those figures. The fire, whose footprint now exceeds the area of Dallas, sent heavy smoke on Saturday into the Yosemite Valley, an area famed for towering granite rock formations, waterfalls and pine forests. It obscured views of popular landmarks on a holiday weekend at the end of the summer tourist season. Fire officials said smoky conditions in the park had largely cleared after a shift in winds on Sunday afternoon. There were no further road closures within Yosemite and containment lines held steady at 40 percent. It's just trying to figure out how to wrap this thing up and put a bow around it," said fire incident spokeswoman Leslie Auriemmo, adding there were no fresh closures in the park. Although the cause of the fire remains under investigation, a fire official with knowledge of the containment efforts told a community meeting in nearby Twain Harte last week that the blaze may have been started in an illicit marijuana-growing operation. The Yosemite Valley has been open to visitors since the fire broke out two weeks ago, but smoke began spreading to the area on Friday, before the Labor Day holiday weekend that in past years has seen the park fill with visitors. Some 620,000 normally visit the park in August alone, but attendance has dropped due to the fire. Close to 5,000 people are working to put out the fire, including firefighters from across California and nearly 700 specially trained California prison inmates. More than $60 million in federal and state money has been spent on fighting the blaze, fire officials said on Sunday. Firefighters have carried out controlled burns around the groves to clear away debris that could otherwise fuel a fire to such an intensity that it threatens the trees. "Ground fire is a good thing, crown fire is a bad thing in his case," said fire incident spokesman Dennis Godfrey. Editing by Eric M. Johnson and Cynthia Johnston and Peter Cooney