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Potential for catastrophic fire threatens Fort Collins water supply

9:55 PM, Mar 31, 2013   |    comments
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GRAND LAKE - Standing on the shore of Grand Lake, it's impossible not to look across the water and notice a row of homes on the far shore sitting directly beneath a mountain flanked with countless dead trees.

The water pouring from your kitchen faucet in Fort Collins is directly linked to whatever happens on that shoreline when the next wildfire roars through Grand Lake - 50 miles as the crow flies and over the Continental Divide from Fort Collins.

Your morning coffee might not have tasted any different after the High Park Fire torched the Poudre River watershed last summer, but Fort Collins' primary source of drinking water was compromised as rain washed ash and silt off the burned slopes and into the river and the city's water treatment plant.

The High Park Fire forced the city to temporarily switch its entire water supply from the Poudre River to the clean, ash-free water of Horsetooth Reservoir, which is filled with water piped beneath Rocky Mountain National Park from Grand Lake and the reservoirs of the headwaters of the Colorado River on the west side of the park.

Wildfires don't occur often in that area because the climate is generally too cool and wet. But with severe drought afflicting forests decimated by bark beetles, a wildfire, when it occurs, is likely to be explosive.

"It's not likely we'll have a fire in a given summer, but if it occurs, get out of the way," said Jason Sibold, a Colorado State University geography professor, forest ecologist and fire historian.

So what will happen when a catastrophic wildfire torches Grand Lake?

The Colorado-Big Thompson Project, a primary source of drinking water for more than 800,000 people along the Front Range from Boulder to Fort Collins, will be compromised, forcing cities to pay more to treat their water and creating a long-term headache for the Northern Colorado Water Conservancy District, whose Grand County reservoirs will be dirtied with sediment, ash and other detritus from the firestorm.

"Any degradation of water supplies in Grand County and Lake Granby and other reservoirs has the potential to affect water quality on the Eastern Slope in reservoirs like Horsetooth and Carter Lake, where a vast majority of folks in Northern Colorado get their drinking water," said Jerry Gibbens, project manager for Northern Water.

Likelihood of a firestorm
The problem with wildfire in Grand County isn't necessarily that millions of bark beetle-killed trees are more likely to burn. It's that the dead trees fall, making fires burn hotter and closer to the ground than forests unaffected by the beetles.

Major wildfires burn about every 150 years or more in the Colorado River's headwaters because the fire season is usually short and limited by the area's late snowmelt and the summer monsoon season. But recently, the climate conditions in Grand County have changed.

"The common thread is drought," Sibold said. "It's not fuels. It's not fuel type. There is a lot of combustible material up there all the time. The thing that drives fire in the system is drought, drought, drought. And that's kind of bad news for us."

Much of eastern Grand County hasn't burned in at least 150 years, which means there's so much wood and other wildfire fuel accumulated in the area that any wildfire that burns there is likely to be huge, he said.

"If we have a fire on the west side of Rocky Mountain National Park, and it's a traditional fire, it's very feasible to see half of the landscape burn on the west side," he said.

"In terms of hazard, these forests are very high hazard," he said. "When they do occur, it's an on-off switch. When it's on, it's a get-out-of-the-way situation - flame lengths hundreds of feet long, fire jumping hundreds of meters in the wind. It's not anything you can put a fire truck in front of."

Nor is such a blaze one you'd want to put firefighters in front of, he said.

"There's so many snags and so many hazards, it's such a big landscape that attacking every fire with everything we have, it's a game changer. We can't do that," said Rocky Mountain National Park Fire Management Officer Mike Lewelling.

More hazards mean fewer firefighters will be allowed to fight the blaze on the ground. And that means bigger wildfires.

"With the changing landscape, more often than not, we'll not be able to send people up," Lewelling said.

Fallen dead trees burning on the ground are hazards to more than firefighters.

"The fire can cause damage to the soil, which can increase the sediment that flows into the reservoir, causing water quality and issues with the water that gets transported to other (areas)," said Arapaho National Forest Deputy District Ranger Matthew Paciorek.

From your tap to your wallet
That means a wildfire far away can hit your pocketbook close to home. It happened after the High Park Fire, and it's a possibility if a catastrophic wildfire burns in Grand County and affects the Colorado-Big Thompson, or C-BT, system.

Here's why:

Once a severe wildfire torches mountain slopes there, intense rainstorms wash soot, silt and debris into rivers and reservoirs - the same reason the Poudre River ran black after the High Park Fire. Large debris can be filtered out of the system, but the sediment and ash may stay in the water as it is piped through the Adams Tunnel beneath Rocky Mountain National Park and into Front Range reservoirs.

"There's no way you can keep out the sediment and the carbon," said Northern Water spokesman Brian Werner. "That will get into the C-BT system and work its way to the Front Range. It's a treatment issue. It costs more. The communities that treat water will have to do changes to how they treat water."

Manganese and other contaminants in the water would spike, possibly affecting the taste and color of tap water and forcing cities to pay more to treat it, said Chris Matkins, water utilities manager for Loveland, which uses the C-BT system as a major source of its water.

The High Park Fire forced Fort Collins to change how it treats Poudre River water, an increased cost that was factored into a 4 percent water rate increase that took effect earlier this year.

But how much more it would cost Fort Collins to treat fire-contaminated water from both the Poudre River and the C-BT system depends on more factors than the city can calculate today, said Kevin Gertig, Fort Collins water treatment manager.

Additional costs depend on the magnitude and type of the contamination flowing into the water, which depends on the magnitude of rainstorms following a wildfire, the severity of the wildfire itself and the geology of the area in which it burned.

Treating water washing off the High Park Fire burn area this year will be good preparation for what the city could face if a catastrophic wildfire burns in Grand County, Gertig said.

"We're going to continue to learn as we start treating this water through the next few months," he said.

There's hope that a catastrophic wildfire in the Colorado River headwaters won't be as catastrophic to water supplies, said John Stednick, professor of watershed science at CSU.

After a wildfire, ash and other contaminants will float to the top of Grand Lake and sediment will settle to the bottom, he said.

Water could be pumped from the lake at a depth where the water is clean, he said.

Follow reporter Bobby Magill at

(Copyright © 2013 Fort Collins Coloradoan, All Rights Reserved)

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