A fire believed to have been sparked by someone in Yosemite National Park is burning near the top of Upper Yosemite Fall, and fire crews are monitoring numerous lightning-strike fires and a hot spot left over from the 2013 Rim Fire in the Stanislaus National Forest.

The Upper Fire was discovered by hikers about 3:30 p.m. Monday above switchbacks at the top of the Yosemite Falls trail, said Gary Wuchner, fire education and information manager for Yosemite National Park.

Fire crews and Yosemite search-and-rescue personnel escorted hikers out of the fire area, Wuchner said. Firefighters with Yosemite Helitack, supported by helicopter bucket drops, held the fire to 3 acres as of Monday night. It had grown to about 5 acres by 9 p.m. Tuesday.

Two helicopters and 14 firefighters on the ground were assigned to the Upper Fire. All trails to Yosemite Falls are temporarily closed.

Elsewhere in Yosemite, the Badger Fire was discovered Monday near Summit Meadows and Glacier Point Road, Wuchner said. Wawona Engine 32 responded and suppressed the fire at about one-tenth of an acre.

The Cathedral Fire, first reported Aug. 2 near the John Muir Trail to Cathedral Lakes, was still smoldering and estimated at one-fifth of an acre. The Middle Fire, reported July 27, was smoldering at 1.5 acres west of White Wolf and south of the Middle Tuolumne River.

The Dark Fire, next to Yosemite Creek Campground Road, has charred about 50 acres, Wuchner said. The Lukens trail is temporarily closed. The White Cascade Fire, east of Glen Aulin High Sierra camp and west of Tuolumne Meadows, was still burning at about two-thirds of an acre.

There were at least two other fires being patrolled by fire crews in the park, Wuchner said.

In the Stanislaus National Forest, the Reservoir Fire, reported July 30 near Donnell Reservoir, has grown to 20 acres, Georgia Dempsey of the Forest Service said in an update. The increased acreage is due in part to a burnout operation on the east flank of the fire.

The Rosasco Fire, described by the Forest Service as a "holdover heat signature from the Rim Fire" that burned more than 400 square miles between August and October 2013, is still holding at 3.4 acres, Dempsey said.

The smoldering fire is near Rosasco Meadow, west of Cherry Lake and north of Woods Ridge, in the Groveland Ranger District.

The Big Creek Fire, which broke out about 4:30 p.m. July 29 and prompted evacuations in the Hells Hollow area east of Groveland, remained 100 percent contained, according to Cal Fire. Lisa Ann Vilmur, 43, has pleaded not guilty to one felony count of recklessly causing a fire. Investigators said the cause of the blaze was an escaped debris fire.