It didn't take much to start the August wildfire in Canyon Park, where a stray Mylar balloon last caused the hillsides to erupt in flames.
The balloon drifted into a power line, triggering an explosion that ignited the thick brush in the park, only part of the thousands of acres above Monrovia that haven't gone up in flames in decades.
Thanks to air support and a quick response from firefighters, the Canyon Park fire was extinguished quickly, causing no damage to structures.
But the two-acre brush fire highlighted the heightened danger of wildfires in Monrovia's hillsides, where a major fire hasn't burned since 1958. Now, city officials are taking additional steps to prepare for a wildfire they deem inevitable.
Fires over the last few years in neighboring cities have left Monrovia's hillsides in a position where they are "effectively the last bit of wilderness in the local mountains that hasn't burned in the last several decades," according to City Manager Scott Ochoa.
"Really we haven't had a major fire in at least a couple of generations," Ochoa said. "The irony there is that actually presents its own host of challenges."
Santa Ana winds always threaten to turn any small forest fire in Southern California into a massive blaze. That risk increases when fuel for fire--in the form of overgrown brush in the city's Wilderness Preserve and the Angeles National Forest behind it--has built up over a period of more than 50 years.
Such dense vegetation makes the potential for a devastating fire in Monrovia's hillsides even greater, Fire Chief Christopher Donovan said.
"When you don't have that naturally occurring fire, … it allows for the vegetation to grow and flourish up there," Donovan said. "The heavier and denser the brush, the more intense it will burn."
In fact, high wind conditions aren't even necessary for a wildfire to rage in a place like Monrovia, said Marty Dumpis, Deputy Forest Supervisor for the Angeles National Forest.
"As the fuels get more dense, then wind isn't necessarily critical," Dumpis said. "If you have areas with very high fuel loadings, they're going to burn hot no matter what kind of wind you have."
Because of the overgrowth in the hillsides, Donovan said a wildfire is guaranteed to ignite at some point. The only question is when, he said.
"We are doing aggressive preparation for that brush fire, which is inevitable," Donovan said.
The topography in the forest above Monrovia also presents serious challenges to stopping wildfires, fire officials said. Full of steep canyons and inclines, the terrain behind the city would be difficult for firefighters to navigate in the event of a major blaze, Donovan said.
City officials thought the wilderness behind Monrovia might finally go up in flames in August 2009, when the Station Fire encroached just a few ridges away from city lines. That historic blaze--the largest ever in Los Angeles County--torched 250 square miles of Angeles National Forest and claimed the lives of two county firefighters.
But instead of dreading the Station Fire as it approached, officials said that they thought it might have presented an opportune time for the thick brush on the hillsides to burn.
Forest service, county and city crews were fully mobilized at that point, so the fire could possibly have been controlled, Ochoa said.
"If that fire was going to come over the ridge, … that wouldn't have been the worst thing," Ochoa said. "We had every necessary resource. We were here ready for the fight, but the fight never came. If ever you had all the odds in your favor to successfully fight this fire, that was it."
The costs of a major fire in the foothills above the city could reach "well into the tens of millions of dollars" if it reached homes, according to Ochoa.
Until the next wildfire ignites, city officials are focusing on preventative measures, especially in the wake of the fire in Canyon Park in August. The city has a strict brush clearance ordinance in place requiring residents to clear 200 feet of defensible space around their homes.
Residents in high risk fire zones are in full compliance this year with the city's brush abatement requirements, according to Ochoa.
But no measures really exist to help abate the brush beyond the 200-foot clearance zones. Because of the topography of the hillsides and the presence of homes in hazardous fire areas, controlled burns are not an option, said Monrovia Deputy Fire Chief Scott Haberle.
"We have an extremely large interface exposure," Haberle said. "I just think there's too much exposure for us to attempt [controlled burns] here locally."
Still, some proactive measures can be taken, Haberle said. The fire department began sending volunteers from the city's Community Emergency Response Team, a federal volunteer program created after 9/11, on weekly patrols of the hillsides last month looking for hazardous brush areas and suspicious activity.
Hillside resident and CERT volunteer Suzi Dobson said the patrols are designed to show residents that people in the community are watching out for neighborhoods in hazardous fire zones.
"I figure the more visible presence, the better," Dobson said. "I'm nervous about [widfires], so having people I know keeping an eye out makes me feel better."
The fire department also brought in an independent fire consultant last month to examine the city's wildfire prevention procedures and meet with hillside residents about fire safety methods.
Steve Miller, hillside resident and former president of the now inactive Monrovia Fire Safe Council, said the fire department is doing a good job in its wildfire preparation. But Miller would like to see residents get more involved in wildfire prevention.
"There's a lot that can be done, and it's a long list of things," Miller said. "It's puzzling to me that more isn't done."
Miller said the city is long overdue in creating a vegetation management plan to mitigate the threat of wildfire. Noting that the Canyon Park fire was caused by a power line accident, Miller also said that Southern California Edison should consider burying power lines that stretch through the forest.
Edison spokesman Steve Conroy said the utility is open to discussion about placing hillside power lines underground but he noted the cost to do that is especially high in mountainous terrain.
Normally, burying power lines costs about $1 million to $1.5 million per mile, but that figure multiplies in foothill communities, Conroy said.
"When you go into a mountain community, it can be 10 times as much," he said.
Edison is currently completing a massive tree-trimming operation in foothill communities like Monrovia, Conroy said.
Residents in the hillsides also need to do their part in the management of vegetation in the hillsides and should refrain from planting anything that can exacerbate fires, Miller said.
"The people who live in the highest risk areas, they know what's burned and what hasn't burned," Miller said. "But I'm baffled by people who turn around and plant redwoods."
Even if a fire does eventually burn off the excess brush in the hillsides, Dobson noted that the aftermath of a wildfire presents another host of challenges for hillside residents.
As La Canada Flintridge residents living next to Station Fire burn areas found out first-hand last February, forest fires leave a tremendous amount of sediment behind. And that sediment can come tumbling down the mountains and pouring into homes when rains hit.
"It's a Catch-22. If it burns and it reduces our fuels, it's a good thing," Dobson said. "The other side of the coin is the mud flow for the next five years."