The massive Aspen Acres fire southwest of Pueblo grew to 86,983 acres on the July Fourth holiday, as hundreds of additional firefighters arrived to shore up defenses against its relentless march.
The number of personnel assigned to the fire grew to 734, up from 498 on Saturday morning and more than double the force on Friday, fire officials said in an update on Facebook. The fire was estimated at 6% contained as of Saturday evening.
“Today was a good day for firefighting,” Zach Fleming, an operations section chief trainee with Alaska Complex Incident Management Team 1, said in an evening briefing.
Milder weather paved the way for “aggressive” operations to combat flames, Fleming said. Aside from building containment on the eastern flank, crews were able to bolster protective lines around homes in several areas, including the fire’s northwestern flank and along Colorado Highway 165 on the western side, he added.
The fire’s growth during daylight hours Saturday — about 1,000 acres — was modest compared with the roughly 10,000 acres of expansion seen Friday evening and overnight, during a period of rapid growth fueled by high winds and dry fuels.
The Aspen Acres fire is the highest-priority fire in the nation when it comes to requests for support, officials say.
The continued growth comes a day after the Aspen Acres fire became the eighth largest wildfire by acreage in Colorado history. It now stands just a few hundred acres behind the High Park fire, which burned 87,284 acres west of Fort Collins in 2012.
The Aspen Acres fire started June 29 in Custer County and quickly spread into Pueblo County as high winds fueled days of rapid growth, leading to the evacuations of roughly 3,800 homes, affecting 11,000 people, authorities said. Parts of Fremont and Huerfano counties were also on pre-evacuation status. All evacuation orders remained in effect Saturday evening.
More than 180 structures have been destroyed, including at least 55 homes in Custer County, fire officials previously said.

Bishop Castle, a popular tourist attraction, was still standing, the Custer County Sheriff’s Office said a Facebook post about 10 a.m. Saturday. The property was evacuated as the Aspen Acres fire spread.
“The front facade is untouched,” the sheriff’s office said. “It appears the back may also be untouched.”
On Saturday morning, officials said the fire had reached Colorado Highway 165 and crossed it in several areas. Fire crews were mopping up burned areas where the fire had passed in Colorado City to extinguish hot spots and prevent the flames from rekindling.
Bulldozers made new containment lines north of Rye and along parts of the western flank of Colorado City as well as the eastern edge of the fire. Crews were also building dozer lines along the fire’s northeastern flank, along Siloam Road and around Galbreath Creek and Wales Canyon.
Part of Pueblo Reservoir is closed to allow firefighting aircraft to refill their water tanks, and boaters are advised to stay at least a half-mile from the dam, from N1 Cove to Sailboard Beach.
Authorities said Thursday the fire was human-caused but have released no details.
The area remains under a hazardous weather outlook that calls for mostly dry weather with lighter winds Saturday, but with a chance for thunderstorms later in the day, according to the National Weather Service Office in Pueblo. Fire officials said they were prepared for wind gusts up to 45-55 mph with the potential to stoke flames and fuel continued growth.
“Satellite thermal detection indicates many areas of heat remain and will be a concern as storm cells form,” fire officials said.
The weather service advisory said available moisture will increase across the region Sunday and into next week, increasing chances of daily showers and thunderstorms.
As the July Fourth holiday approached, fire officials pleaded with the public to forgo fireworks and avoid creating other fire sources, warning the errant sparks can easily ignite new fires at a time resources have already been spread thin among five major Colorado wildfires, collectively burning nearly 180,000 acres.

Ferris fire
The Ferris fire in southwestern Colorado grew to 41,337 acres and was estimated at 7% contained Saturday evening, a slight decrease from an earlier estimate of 9%.
The fire swept through the Dolores River Canyon on Friday and grew on its western flank, increasing the threat it posed to residential areas.
Two Super Scooper planes were expected to join the more than 300 personnel assigned to the blaze. The planes, which fly 100 mph as they scoop up water to refill their tanks, were expected to be flying in and out of McPhee Reservoir.
Snyder fire
Crews battling the Snyder fire west of Grand Junction reported major progress overnight, estimating the 30,202-acre fire was 95% contained, up from 65% a day earlier.
All evacuations and pre-evacuations from the fire on the Colorado-Utah border were lifted as of Thursday.
The blaze previously merged with the Jones fire and later overtook the Knowles and Gore fire. Firefighters Emily Barker, Nick Hutcherson and Sydney Watson were killed June 27 while fighting the Knowles fire.
Gold Mountain fire
The Gold Mountain fire northeast of Ouray in western Colorado is now estimated at 25,920 acres, an increase of more than 4,000 acres from Friday.
In a video briefing Saturday, fire officials reported encouraging progress in the Lake Lenore area on the fire’s southwestern flank, where homes and other structures could be threatened by further spread.
“Fire activity has diminished a little bit, but we still want to have a strong presence in there,” said Jeramy Dietz, operations section chief Rocky Mountain complex incident management Team 3.
Hand crews and helicopters were working to bolster containment lines along Cutler Creek to further protect the western flank.
Along the fire’s northern boundary, officials were working on a three- to five-day plan to defend against potential growth. A group of water tenders was stationed in the area to help protect structures.
Willow fire
The Willow fire, burning 6 miles west of Leadville, grew by several hundred acres to 3,090 acres as of Saturday night.
Firefighters spent Friday in the Twin Mounds area at the base of Mount Massive “to limit damage to nearby power lines as fire continues moving in a downslope direction toward Turquoise Lake,” a previous update said. “An initial attack contingency group is being established north of Turquoise Lake should the fire cross the lake.”
