Fire management officials and homeowners living in the heavily wooded, steep mountainsides, draws and canyons west of Boulder had planned for years for the fire that swept through the area on Labor Day.

They spent thousands of hours and hundreds of thousands of dollars cutting down trees, trimming branches and clearing brush and pine needles from the forest floor to remove fuel for such a fire.

Forest managers say those fire mitigation efforts worked, by some measures. There were no reported serious injuries or deaths from the 3,500 people who were evacuated or firefighters battling the blaze.

Though 166 homes were destroyed, making it the most destructive fire in Colorado history, there were more than 500 homes within the 6,200 acre footprint of the fire — nearly 10 square miles — that survived, according to figures compiled by Laura McConnell, a firefighter with the Boulder Mountain Fire Protection District.

That's little consolation though, for people who lost their property.

"I'm questioning the whole mitigation thing," said Laurent Nicault as he and his family removed belongings from their fire-damaged home. A garage, apartment and a car on his property laid in charred ruins. He had removed several trees and taken other measures to prevent exactly that type of loss.

U.S. Sen. Mark Udall, a resident of Boulder County and a long time supporter of mitigation efforts, has called for a review into whether those efforts were effective, as well as whether firefighters had enough air support and other resources.

The fire wreaked most of its devastation in the hours after it started on Labor Day. Officials are investigating reports that the blaze escaped a fire pit then blew up a propane tank, sending flames into the trees.

Once in the trees, winds gusting to 60 mph and focused by the draws, ravines, and canyons pushed intense walls of fire through the area. Fire behavior analyst Tyler Doggett described how monstrous flames bent nearly horizontally by the wind quickly dried out and heated nearby stands of trees which would then burst into flames, a process repeated throughout the day. Showers of embers rained down on hillsides up to a half mile away, starting fires that took out hundreds of acres of trees, along with homes.

"People understand that you can't stop a hurricane or a tornado," said Justin Dombrowski, a former Boulder County emergency planner who now works for the Federal Emergency Management Agency in California. "When the fire gets up into the trees and creates a firestorm, it's like a hurricane or a tornado. All you can do is make sure that people are out of the way."

Firefighters on the ground with axes, picks, shovels, fire trucks and a small air force of planes and helicopters were no match for the fire. It burned through areas where trees had been removed, and destroyed homes and buildings, such as Nicault's garage and apartment, where homeowners seemingly did everything right.

However in many instances, fire mitigation efforts did help, said Allen Owen, a state forester in charge of the area. Trees had been strategically thinned out around winding, narrow canyon roads which served as evacuation routes. Firefighters were able to make stands against the inferno in places where homeowners had cleared their property.

"When we're driving up those roads, see the flames and look at homes, we have to make a split decision on which one to save, which one we can save" said Rocco Snart, a wildfire mitigation specialist in neighboring Jefferson County, who was part of the federal firefighting team.

Forest managers have begun examining the charred forest to see how their mitigation efforts worked, including how the fire was moving and how it behaved when it hit cleared areas, said Owen.

"All we can do is reduce the risk," Owen said. "It's not fireproofing."

Mitigation efforts in the area had included communities banding together to plan for catastrophic fires, even if it meant convincing neighbors to cut down some of their trees.

Flames got within a half mile of the Poorman neighborhood on the eastern end of the fire, where about 30 homeowners had cut down trees and collectively purchased a plot of land for a community park, which served as a staging area for firefighters.

"These huge conflagrations aren't as likely as the relatively small ones," said Vera Evenson, a community leader who has lived in the mountains since 1965. She said the last major fire in the area happened in 1989. "That's how we know mitigation works."

Over the past three years, the county and state has spent about $800,000 on fire mitigation in the area, with thousands more spent by local fire districts and homeowners. Federal figures for the area weren't immediately available, though Udall spokeswoman Jennifer Talhelm hopes that the review will help answer that question.

Nationwide, the federal government treated 29 million fire-prone acres between 2001 and 2008, according to a study led by the University of Colorado at Boulder.

Across the country, there are 44.8 million homes in the so-called wildland urban interface, where homes are built among forests, shrubs, and grasslands, similar to the subdivisions west of Boulder, according to the U.S. Forest Service. Effective mitigation is key, emergency managers say.

In the burn area west of Boulder, there are three areas where fire managers cleared trees with an eye toward restoring the ponderosa pine forest to what it looked like before the area was populated. The practice isn't popular with some residents.

"It takes out a lot of trees," said Chad Julian, a forester for Boulder County Parks and Open Space.

Julian cites studies that show ponderosa pine forests historically had only dozens of trees per acre, and they grew in clumps with open spaces between them.

Left untouched, fires would burn through the wild forests about every 30 to 50 years, taking out pine needles and other debris on the forest floor and leaving large, hardier fire resistant pines to thrive. It created a growth pattern that naturally prevented catastrophic fires.

The ponderosa restoration areas, which seek to mimic nature, seemed effective against the giant blaze.

But there are areas remaining where there are hundreds of trees per acre remaining, and in some places thousands, Julian said.

"We need to cut more trees. There, I said it," said Owen, the state forester.

One neighbor wasn't convinced.

"They cut down way too many trees," Penny Trotta said, whose home is adjacent to Bald Mountain, where Julian and his team removed hundreds of trees in the restoration effort two years ago. "I don't know if it would have been too different if there were a few trees."

As it was, the fire burned right up to her concrete patio, but her home survived.

Michelle Seman, who stood with Trotta surveying the scene, disagreed with her friend.

"I think it saved your house," she said.