© 2024
NPR for Northern Colorado
Play Live Radio
Next Up:
0:00 0:00
Available On Air Stations

New study confirms Marshall Fire contaminated drinking water, but the response prevented a crisis

A fire burns in a home destroyed by the Marshall Wildfire in Louisville, Colo., Friday, Dec. 31, 2021.
Jack Dempsey
A fire burns in a home destroyed by the Marshall Wildfire in Louisville, Colo., Friday, Dec. 31, 2021.

A new study on the Marshall Fire reaffirms the need for better guidelines to safeguard water systems from contamination as wildfires burn through more residential areas.

Andrew Whelton, the study’s lead author, hopes lessons from the Marshall Fire can help other communities avoid the worst future fires have to offer.

“The Marshall Fire was the most effective disaster response to a damaged water system that I’ve ever been a part of,” he said.

Whelton, a professor of civil, environmental and ecological engineering at Purdue University, flew out to Boulder County days after the Dec. 30, 2021 disaster to study the damage to water systems and municipalities’ response. His study, published in American Water Works Association in January, helps answer, at least partially, the question of how much contamination occurred and what can be done to improve wildfire water safety.

The fire damaged six public drinking water systems: Louisville, Lafayette, Superior, East Boulder County Water District, Eldorado Artesian Spring, Inc. and the Sans Souci Mobile Home Park. Toxic chemicals leaked into pipes from damaged homes and into hydrants where low water pressure created vacuums that pulled the compounds into the distribution system.

In Louisville, some chemicals remained at unsafe levels for weeks after the burn, evading several flushes of the system. That includes benzene, a volatile organic compound, or VOC, that has been found to cause cancer in the long term.

Superior not only had ash fall into its source water but the town’s water treatment plant lost electricity and the plant’s backup generator was destroyed. Superior’s residents complained for months after the fire that their water had a smoky, chemical flavor. In the year since, Superior spent more than $4.6 million on their water system response and recovery. Louisville spent roughly $1.4 million.

Superior’s reservoir is being treated to remove any potentially harmful semi-volatile organic compounds that caused the smoky flavor.

Whelton’s study, more than anything, validates struggles other municipalities have faced after wildfires destroyed entire neighborhoods and chemicals lingered in the air and water. Because the field is so new, there is a lack of established guidelines on how to properly test water after a wildfire and what to test for.

“When the fire occurred, all utilities [in Boulder County] were not aware of what, where, and how to collect post-fire water samples,” the study said. This lack of awareness could mean that contaminated water was consumed or bathed in. A primary concern was exposure to VOCs, such as benzene.

Though Whelton said none of the public water systems were prepared for what took place in the Marshall Fire, municipalities in Boulder County were the most proactive he had seen. (He’s been a part of several water disaster recoveries, including the 2017 Tubbs Fire and the 2018 Camp Fire in California, the Joint Base Pearl Harbor-Hickam contamination, and a chemical spill in West Virginia.)

Water testing was an illustration of this. Though there wasn’t an established framework of what to test for, those in charge were “hungry for information” and willing to learn from anyone with credentials.

“The municipalities impacted by the Marshall Fire all were open and proactive to making the best decision they could, and finding resources to make that decision,” Whelton said. “I’m using them as examples to other communities.”

“Sometimes the water utilities will say, ‘We don’t have to test for anything, so we’re not going to,’” Whelton said. Not Boulder County.

But the response was not without mistakes and failures. Boil water advisories were not consistent, for one.

When water is contaminated, boiling it is insufficient and can lead to chemicals off-gassing into the home. Meaning, people drink fewer chemicals only to inhale higher levels of the compounds.

“The boil water advisories were not designed to protect customers from being exposed to chemically contaminated water,” the study said. Among the six water systems affected, “only Louisville urged their customers to avoid drinking and contact with water as they conducted sampling and ultimately found contamination.” (The East Boulder Creek Water District found chemical contamination several weeks after the state lifted the boil water advisory.)

The lack of coordination “underscores a much larger public notification problem associated with wildfires,” in Colorado, the study said.

When smoke gets into the water system

Depressurization is a top water quality concern for a town struck by fire. To get water from treatment plants to homes and businesses across a city, water is pressurized. If pipes are damaged — or the distribution system runs low on water — that pressure is lost. This creates a vacuum that sucks smoke and chemicals into the water system. Louisville lost water pressure during the Marshall Fire, and high levels of contamination were found in its distribution system after. Lafayette did not lose pressure and contamination was minimal.

Flushing the system so contaminated water is replaced with a fresh batch from the treatment plant is one way to mitigate contamination.

Knowing this, flushing was a priority post-Marshall fire, especially in Louisville that both lost pressure and pumped lake water into their distribution system to aid firefighters. “After the fire was contained, all water systems first focused on damage assessment, flushing, and re-pressurizing their water distribution systems,” the study said.

And yet, “contamination in Louisville remained at select locations above the benzene maximum contaminant level for weeks,” even after aggressive flushing. Three months after the fire, testing showed no contamination.

One reason contamination in Louisville might have persisted despite flushing is overheated plastic pipes. Some plastics, when heated by a fire, can leach benzene and other chemicals for months or even years. In Whelton’s research, plastic pipes were primed to leach chemicals by temperatures as low as 392 degrees Fahrenheit. Wildfires can exceed 1,400 degrees.

Also, if municipalities do not flush their systems quickly enough after a fire, chemicals sucked into the system via pressure loss can soak into plastic pipes, even if those plastic pipes weren’t heated, and leach out over time. Someone in the same distribution system, though far from the burn scar, could be exposed to carcinogens over time without knowing it.

“The longer contaminated water sits in the water mains, plumbing, etc. the greater potential you have of that infrastructure posing a serious health risk to the users,” Whelton said.

‘Severe’ issues with water testing post-fire

Testing is critical to identifying contamination early on.

In the Marshall Fire, not only was there a lack of coordination on when and where to take samples of water, there was a lack of capacity to then test those samples. The study revealed “several chemical water sampling and analysis issues” that made understanding the full scope of contamination unclear.

“For Louisville alone, six commercial laboratories were contacted for assistance,” the study said. “Some laboratories did not respond to requests, lacked sampling supplies, and stated they could not promptly provide results to the water system.”

Preparing for future fires, it’s important municipalities and labs understand how to properly test drinking water for contamination after fires, the study urged.

It’s also important to rethink water distribution systems to better prevent such contamination in the first place.

One of the main solutions offered by Whelton in the Marshall Fire study, backed by experience from previous fires, is “zoning water systems.”

By splitting a water distribution system into zones, if one area of town gets hit by fire, heated pipes leaching chemicals or contaminated water can be quarantined from other parts of town. Doing so on a large scale would entail breaking a city into sections like North Boulder, East Boulder, and so on.

On a smaller scale, remote shutoffs for each building could cut individual homes off from the system when needed, protecting nearby buildings and the water system as a whole.

Such shutoffs would have preserved water in the Marshall Fire and kept more people out of harm’s way. While the fire burned, Louisville and Superior Department of Public Works employees went into the fire zone where “structures around them were on fire” to “stop the bleeding” of water from houses that were no more.

“They were shutting off these valves located at the street so the homes that were burned down, with water shooting out, would stop leaking,” Whelton said. “Because that was draining the water system and firefighters needed that water.”

At the time of the study’s publication, insurance hadn’t kicked in to cover the costs of damaged water systems. Municipalities were relying on stored cash to make needed repairs. As they wait on insurers and FEMA for aid, those cash pools will continue to drain. The water systems are still recovering.