How bad the runoff from the 416 Fire burn scar will be is going to depend on how quickly the snow melts, Butch Knowlton, director of La Plata County’s Office of Emergency Management, said Tuesday night.
Speaking to more than 50 residents at the Animas Valley Grange, Knowlton reflected on how much difference a year makes.
“What were we doing this time last year?” he said. “We were sitting around worrying about no water and no snow.”
Indeed, last year’s drought conditions set the stage for the 416 Fire, which sparked June 1 and went on to burn an estimated 54,000 acres of mostly San Juan National Forest land north of Durango.
But the blaze itself is only one part of the 416 Fire’s impact. Soils that have burned no longer have the ability to absorb water, so when heavy rains hit or when snow melts fast, there is the potential for destructive mudslides and debris flows.
These fears were realized in a series of flooding events in July and September.
“It was quick, and we couldn’t predict it real well,” Knowlton said of those floods. “When it rained a third of an inch in a short period, we saw huge volumes of ash and debris and rock coming out of ravines and canyons.”
This past winter has been a different story, with consistent storms bringing the region’s snowpack to 163 percent of normal, historic averages as of Monday. Knowlton said he’s heard reports that snowpack at the headwaters of Hermosa Creek is 10 to 12 feet deep.
The fear now, Knowlton said, is that high temperatures could cause the snow to melt fast or rains could hit the snowpack – both carry the risk of heavy flooding.
“I wish I could tell you it’s going to be good or it’s going to be bad, but I can’t,” he said. “If you tell me what the temperature is going to be in the next four to five weeks, I can tell you how much water is going to come down.”
Knowlton also said it’s critical nighttime temperatures remain cold.
“If at night it stops freezing at upper elevations, we’re going to have a lot of water in the valley,” he said. “And we’re going to get in trouble. There is a potential for some bad days.”
To prepare, Knowlton said emergency officials plan to install temperature and rain gauges around the Animas Valley and 416 Fire burn scar. Officials also say it’s likely the portable radar system will return to help track storms. And, he urged residents to sign up for the county’s emergency notification system.
The National Resource Conservation Service is offering to help private landowners mitigate their property for flooding risks. But most of that work can’t occur until crews can get out on the ground, after the snow melts.
Knowlton said the areas most at risk are homes in the path of Tripp, Buck and Dyke creeks.
“We still have a lot of homes … that were built in natural hazard zones,” he said.
One resident commented that the drainage that damaged the KOA Campground last summer wasn’t considered a high-risk area.
“I think everyone has to be worried if they’re around a drainage,” he said.
Brian Devine, water and air-quality program manager at San Juan Basin Public Health, said water and sediment samples were taken at affected areas, including the Animas Consolidated Ditch.
None of the samples had metal concentrations that held concerns for agriculture, livestock or recreation. And most residents in the Animas Valley get their drinking water from groundwater sources.
As for how water quality will be affected during spring runoff, Devine said there’s still a lot of unknowns. Most of the forest burned at low to moderate intensity, and already, officials are starting to see vegetation regrowth, he said.
Devine said that, like usual, water quality will typically worsen during storm events. But he doesn’t have concerns it will have lasting impacts.
“I don’t expect anything other than those peaks during storm events,” he said.