The Marshall Fire as seen from the City of Boulder on Dec. 31, 2021. Credit: John Herrick

House fires once primarily began from within. Whether through faulty electrical boxes or overzealous water heaters, firefighters used to face infernos whose origins lay in structures’ depths.

But as appliances continue to modernize and building codes root out the most common causes of house fire, concern no longer lies within a home’s basement or walls; for Boulder and other towns in landscapes made to burn, the main risk of incineration prowls outside their borders.

In a previous story, Boulder Reporting Lab spoke with Jim Webster of the Wildfire Partners program, which helps unincorporated Boulder County residents reduce the risk of wildfire on their property. BRL subsequently toured a property certified by the program to get a taste of the doled out advice.

However, as the Marshall Fire showed, fire does not differentiate between unincorporated space and the town proper. Flames will sate themselves on a home nestled at the end of a cul-de-sac the same as one secluded in the mountains.

Brian Oliver, the City of Boulder’s Wildland Fire Division Chief, said when city residents previously considered wildfire encroaching on town, most thought: “Oh, that’ll never happen here,” or “It might happen here, but whenever it gets close the fire department always puts it out.” Yet Oliver said that above all else, the lack of fire thus far in Boulder proper could be attributed to good fortune.

“The fire department’s gotten really lucky,” Oliver said. “You get all the conditions lining up, like they did in the Marshall Fire, and there you go. And we get conditions like that on a regular basis. So I think everyone’s starting to look through that lens and thinking, ‘Oh crap.’”

Wildfire does not march methodically through the landscape, only burning a new section of forest after exhausting the fuels of the last. Often, wind will take burning pinecones or branches and throw them hundreds of yards forward, starting spot fires that grow and join their begetter. So it isn’t hard to imagine fire cresting a mountain beside Boulder with a westerly wind delivering embers from the burning ridge deep into the city.

“A big concern is not necessarily the flaming front impacting the edge of the city,” Oliver said. “It’s the embers landing in receptive fuels somewhere in the city and going undetected, starting a house on fire. Then you get into that Marshall Fire scenario where it’s no longer a wildfire but instead a home-to-home ignition problem.”

Receptive fuels: that mulch so carefully laid around one’s house or the tired wooden fence edging one’s yard.

“If [residents] get rid of that receptive fuel, they’re not going to have an ember land there and start their home on fire,” Oliver said.

Chris Wanner, the City of Boulder’s vegetation stewardship senior manager, addressed various flora Boulderites put near their homes as unassuming fire encouragers, giving special attention to a plant that seems to come up in every conversation BRL has about fire mitigation.

“The ground juniper is a really common landscaping species,” Wanner said. “It covers the ground and grows real quick. But it is probably one of the worst things you can have up against your house in a wildland-urban interface.” 

Some Native American tribes traditionally use resins from junipers to treat colds and rheumatism. Health and wellness blogs also tout the benefits of juniper oils, asserting they relieve symptoms of sepsis and menstrual cramps while also promoting sweating and urination. But these cold-treating, urination-promoting resins and oils are what make junipers a poor landscaping choice in fire-prone areas. Highly flammable, these compounds allow junipers to quickly catch and spread fire.

“And you look around town and everyone’s got junipers in their yard,” Wanner said.

Shifting perspectives 

But the Marshall Fire is changing how some people think about fuel management. As Wanner said of shifting perspectives on thinning projects, Oliver noted the shifting tone of calls received by his department. Before, people accepted dead and downed woody material as an eyesore, but a natural one.

“Now, if there’s a buildup of fuel, we’re getting inundated with calls of ‘Hey, you need to come out here and look at this.’”or “You need to come clean this up, it’s a fire hazard,’” he said.

Though not everyone is on board. 

“There’s still a lot of: ‘Why are you cutting those trees down? Don’t change my open space. This is natural. This is how it’s supposed to be,’” Oliver said. “Then the very next person you talk to says you should be cutting down twice as many.”

Oliver emphasized that while he and Wanner (and their respective teams) can deal with fire risks on public land, calls regarding private property pose a challenge. Your neighbor could have a dead tree, or several, in their yard, but if they don’t want to do anything about it, not much can be done.

“Where I see it going eventually — because not everybody is going to take that tactic and say ‘We need to do this for ourselves’ — is something like our wood shake roof ordinance: Fire-wise landscaping and an ordinance saying you have to move combustible material a certain distance from your house,” Oliver said.

According to Oliver, when South Boulder was first developed, wooden shakes and shingles were the default roofing material in many neighborhoods. Their woody appearance melded marvelously with the surrounding nature. Yet such shingles and shakes, when introduced to embers thrown from a wildfire, also burn marvelously, igniting alongside the landscape with which they’re meant to camouflage. In 1994, the City of Boulder passed an ordinance banning the use of wooden shakes and shingles due to the aforementioned wildfire risk.

In Colorado, where a historical spirit of individualism lives on, more legislation about what one can and cannot do with one’s property will likely face pushback. But when concerning wildfire, especially in a place where flames can jump from wilderness into town, a collective mindset is necessary to avert catastrophe.

“If one house in the neighborhood does the mitigation but nobody else does, it won’t make a big enough difference to help,” Oliver said. “It has to be a community wide effort.”

California already has laws requiring citizens to keep potential tinder on their property to a minimum. Rather than the recommendations for risk reduction that Boulderites receive, those in the Golden State get fined should they not properly mitigate fuels. Oliver said Boulder could adopt a similar strategy not too far in the future.

“We’re already moving in that direction,” Oliver said. “It’s just a matter of how far into the city do we adopt that [potential] code, and how far reaching do we go as far as vegetation management and mitigation.”

Perhaps sooner than later, even those in the heart of Boulder will have to mind their landscaping choices, or be penalized for not doing so.

Tim Drugan is the climate and environment reporter for Boulder Reporting Lab, covering wildfires, water and other climate-related issues for Boulder with a focus on explanatory and solutions journalism. He also is the lead writer of BRL Today, our morning newsletter. Tim grew up in New Hampshire and graduated from UNH with a degree in English/Journalism. Email:

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1 Comment

  1. This is a good heads up. The article mentions ground cover junipers planted next to a house as being fire hazards, or more accurately, fire spreaders. I imagine there are other plants and practices to avoid, or to encourage, in the effort to minimize fire danger. Maybe the city of Boulder could take an action item to provide an ongoing source of best practices for folks to consult. I, and likely many others, would like to learn more.

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