Glenwood Springs’ waterways could be impacted by sediment, landslides long after Grizzly Creek Fire
Glenwood Springs and the surrounding area could be susceptible to landslides for years to come following the Grizzly Creek Fire, post-fire recovery specialists told the City Council.
During the council’s regular meeting Thursday, specialists presented a series of debris-flow models and soil-burn estimates as part of a potential fire-impact report.
“Recovery is a marathon,” said Carol Ekarius, the Coalition & Collaboratives, Inc., CEO. “This is going to be with you for years.”
In addition to working with After the Flames, a post-fire support organization, Ekarius works on national-level policy around the nexus of forests, wildfire and water.
Fire scars, the scorched area left in the wake of a large wildfire, do not have vegetation to keep soil and sediment intact during large rain events, and fires that burn with the intensity of Grizzly Creek Fire tend to leave scars that can lead to disastrous landslides, or debris-flow events.
Ekarius said these events are not simply a first-year concern, but can happen several years after a wildfire devastates an area, depending on how quickly the vegetation regrows.
Using satellite data presented by Dave Callery, a U.S. Forest Service hydrologist and post-fire specialist, Ekarius said several areas throughout the fire area have an 80-100 percent chance of becoming a debris-flow event, including one area near No Name Creek.
“You have one of the most important roads in the state that is in the way of this thing,” she said. “Get money to start sandbagging now.”
Glenwood Springs should also begin to assemble a recovery committee formed with Garfield County officials, railroad representatives, Colorado Department of Transportation and other stakeholders, Ekarius advised.
“The more you have a recovery committee — and people are singing from the same song sheet — the better off you are,” she said. “This is an issue that could affect all of you.”
All it could take to set off a debris-flow event is a rain event that dropped about a quarter-inch of precipitation in about 15 minutes, which Ekarius explained is fairly standard for the area during the summer.
Callery said climatologists have acknowledged fire scars tend to create their own weather and are prone to receiving more intense rain events in the years following a fire.
Another map, illustrating soil-burn severity, showed most of the fire area registered in the moderate- to severe-burn category, though Callery said the data was preliminary at the moment.
“There’s quite a bit of (soil burn),” he said. “Those are the areas we expect to be fairly reactive to rain in the next 3-7 years.”
Life threatening land-slides are only one of the problems presented by fire-scar sediment runoff.
Christina Burri, a Denver Water Department watershed scientist, said large amounts of sediment can wreak havoc on a city’s waterworks.
“It’s been over 20 years since the two big fires that impacted our watershed,” Burri explained. “What we’ve seen post-fire are the ongoing impacts to infrastructure, water quality and treatment. These burn scars are perpetual sources of sediment and water quality impacts.”
Sediment can damage water treatment equipment, and Callery added high amounts of carbon in runoff mixed with the chlorine during the treatment process can create a hazardous situation in a city’s drinking water.
In the short term, run off can increase levels of manganese and algae in the water supply, but damage to watersheds in the long term could significantly impact the city’s public works budget.
“There’s a huge cost associated with dealing with the sediment over time,” Burri said. “The sooner you can start that recovery process of stabilization and re-vegetation efforts, the better.”
Ekarius offered the City Council several sources for grant funding to help with post-fire watershed recovery, but not without a caveat.
“You’re going to use more chemicals in your water plant, you’re going to use more electricity,” she said. “You need to be prepared for those long-term costs, because there aren’t grants or agreements to help with those costs.”
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