Wildfires have lasting effects on drinking water supplies long after they’re put out
On a cool, cloudy day in Superior, Colorado, a gentle breeze blows ripples and waves across a small reservoir outside of the town’s water treatment plant. Just a few months ago, this placid little pond was cornered by flames.
In December, the Marshall Fire tore through these foothills. It quickly became the most destructive in Colorado’s history, claiming more than 1,000 homes in the area before it was extinguished the next day. The fire left its fingerprints on the town’s residents and the neighborhoods they called home. It also lingered in its water, leaving a smoky taste and smell in the drinking supply. That forced an expensive fix, the likes of which could also come for other communities across the western U.S. where wildfires begin to burn in areas they never have before.
Alex Ariniello, the town’s public works director, remembers the day of the fire. In this small Boulder County suburb, he has a wide-ranging set of duties. The backseat of his car carries to-be-installed road signs as he pulls up to the water treatment plant.
Looking out over the reservoir, he described a chaotic day, when the grassy fields behind the reservoir were ablaze, flames quickly encroaching on the pond and adjacent buildings. The water treatment plant was largely unscathed, save for a pump station and backup generator across the road from the main building. But on that day, winds dumped charred debris straight into the water.
That presented a problem for two reasons. First, virtually every drop of water that comes out of Superior’s residential faucets passes through that pond. It’s relatively small, only holding 400 acre-feet. One acre-foot generally provides enough water for one to two households for a year. This pond is the last stop in a long chain of canals and streams that brings water down from the mountains to Superior, so a problem with the water here is a problem for homes throughout town.
The second is that the taste and smell just wouldn’t go away, even once loads of burned bits were pulled out of the water. Charred fragments of grass and debris were vacuumed out, but the taste and smell lingered, perhaps in tiny particles invisible to the naked eye.
Water from the reservoir even passed state standards for quality. The water was safe to drink, albeit unpleasant. In the subterranean bowels of the water treatment plant, Ariniello spoke loudly over the mechanical whir of the purification equipment behind him. The pools and pipes and chemicals are enough to remove the things that make people sick, but not the taste and smell.
“The ash gets through,” he said. “Maybe it's microscopic. Maybe it's not reacting with those chemicals. It just was getting through and causing those issues.”
Ariniello and his department have been tasked with fixing the issue because they received a steady stream of complaints about how the water smells and tastes, especially when it’s heated.
“We've had people really upset about it,” he said, “and a lot of people are very sensitive to it. So there are those people that we really need to address. They call us all the time – ‘The water's terrible, and I can't take a shower.’ They're very afraid about the water. So we're trying to alleviate those fears.”
The recourse is an extra layer of purification. But since the problem is invisible and doesn’t make the water unsafe to drink, it’s hard to figure out exactly how to fix it. Just down the street from the water treatment plant, a team of scientists has been running tests to isolate the problem and figure out the best way to remove the traces of smoke.
The lab would look pretty familiar to anyone who took a science class in high school. There’s high-tech electronic equipment, alongside the tubes, flasks and eye protection you’d find in third-period chemistry.
Anthony Kennedy, a water process engineer with Corona Environmental Consulting, is wrangling this experiment. The firm was contracted by Superior to get to the bottom of the taste and odor issue. He starts on the low-tech end, ripping open a white garbage bag full of debris vacuumed from around the edges of the reservoir. This is the source of the problem.
Kennedy picks up a handful of tiny twigs and stalks, mostly brown with some char around the edges. They smell earthy and musty, with hints of campfire when you stick your nose closer to the pile.
Through a snaking system of barrels, tubes, and pressurizers, water with traces of this debris is pushed through four different kinds of filters and collected on the other side. Then, it’s heated up. It would be complicated and expensive to figure out exactly what is causing the smell and taste issue. Researchers know that it’s an organic compound – two elements bonded together at the atom level – but they’re more concerned with removing it than giving it a name.
So instead of testing the effectiveness of each filter with high-tech scientific gear, they use the human nose. Employees of the consulting firm sniff each sample of purified water, and give it a thumbs up or thumbs down for a smoky smell.
“We're basically simulating what the residents of Superior are experiencing,” Kennedy said. “So we're just saying, if this water is this hot coming out of my shower or my sink, am I smelling it here? And that means they would smell it there.”
From those tests, a clear winner has emerged; granular activated carbon. They’re little granules of coal. Kennedy held up a handful of the black sand. Huge quantities of this will be placed in tanks at the water treatment facility, adding a new line of defense against the persistent taste and smell.
“This is the same stuff that is in your Brita filter at home,” he said, gesturing towards a container about the size of a soup can. “We're looking at like a pound here. So 20,000 of these will go in one of those large pressure vessels. Picture a propane tank, but picture a propane tank ten feet in diameter.”
The key to the carbon’s cleaning power is in the unique structure of each granule. The little black chunks look solid, but they’re incredibly porous. Because organic compounds stick to carbon’s surface, it’s a big advantage to use something with a massive surface area.
“On its surface here, it doesn't look like there's much to it,” Kennedy said. “But actually, if I picked up a gram of these particles – like a little pile that fits in my hand – that much of this material has about a thousand meters squared of surface area.”
Superior may be on track to a permanent fix for the smoky-smelling water that has annoyed some residents since the Marshall Fire. But it’s been an expensive and complicated process for the town. The installation of the new purification tanks and pipes alone is costing the town $1.5 million. In a town of about 13,000 residents, that’s a big enough chunk of the budget that other projects had to be put on the backburner. Superior officials say it was a necessary step, despite some public opposition to the use of town money to remedy the problem.
Similar issues and expenses may be on the way for other communities around the western U.S. Climate change is driving changes to the role of wildfires, as they are happening more frequently, closer to towns and cities, and outside of the traditional “fire season.”
“It starts with recognizing that this is likely to be of concern and impact you,” said Chad Seidel, president of Corona Environmental Consulting.
Seidel got his PhD in environmental engineering at the nearby University of Colorado Boulder, where he currently holds an adjunct position.
“[Wildfires] just keep getting closer and closer to home,” he said, “and the conditions under which we experience them are just more and more often. And so communities who might have thought, ‘Oh, we're not really in the forest, we don't have to worry about wildfires.’ That's not the case.”
Other scientists agree. Climate experts point to the fire that hit Superior as a warning sign that climate change is pushing fires closer to cities and the infrastructure that keeps them running.
“With larger human populations and a changing, drying climate, the impact of fire on humans and the hazards faced by our natural and developed world will continue to increase,” writes one study from the U.S. Forest Service.
Other research has outlined the impact of wildfire on transportation infrastructure and electric utilities. Researchers have chronicled the extent of loss from wildfire that increasingly damage homes and other buildings, but say there isn’t similar data collection for the impact of wildfire on utilities. But the science all seems to point in one direction – that wildfires will break out more frequently, closer to people and utilities, and force expensive fixes that last long after they’re put out.
This story is part of ongoing coverage of water in the West, produced by KUNC in Colorado and supported by the Walton Family Foundation. KUNC is solely responsible for its editorial coverage.
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