Mora County wells reveal high levels of heavy metals

Testing of private drinking water raises health concerns; cause of contamination could be from 2022 firefighting efforts

Three years after the Hermits Peak/Calf Canyon Fire, a slew of heavy metals have been detected in groundwater in Mora County.

While no one is sure of the exact source, they could have come from burned materials or firefighting efforts. Heavy rains earlier this year may have allowed wildfire-related contaminants to reemerge.

Eleven metals were found at elevated levels in groundwater samples from private wells, including three — antimony, arsenic and uranium — at levels above U.S. Environmental Protection Agency drinking water standards, and one, manganese, above an EPA lifetime health advisory.

The state Department of Health is advising well owners in Mora County to get their wells tested for heavy metals and warns that boiling water is ineffective at removing them. In a Friday news release, the agency recommended residents rely on bottled water to avoid exposure.

“There are potential long-term health effects that can develop over several years if people continue to drink untreated water with these levels of metals,” Chelsea Langer, bureau chief for the state Health Department Environmental Health Epidemiology Bureau, said in a statement. “The only way to know for sure what is in your well water is to have it tested by a certified laboratory.”

‘Confirmed my fears’

Zeigler Geologic Consulting has been monitoring wells since 2023 in the area of the county impacted by the state’s largest wildfire, using funding from the county and an anonymous donor. Kate Zeigler, the firm’s owner and

senior geologist, said there was an unexpected increase this year in antimony and manganese at monitored sites, which she believes could be due to intense rainfall earlier this year unearthing contaminants.

“When we look at the distribution of where we see antimony on the mountain, we see it everywhere,” Zeigler said. “It’s in every drainage, whether or not we burned houses down in that drainage or not. It’s everywhere out there, and the manganese as well.”

Zeigler had previously monitored water quality in the eastern part of Mora County, largely within the Mora-Wagon Mound Soil and Water Conservation District. Post-wildfire monitoring was new — Zeigler’s consulting firm had previously focused on groundwater monitoring for agricultural communities.

Initially, groundwater monitoring in Mora County after the fire showed elevated levels of nitrate and orthophosphate. That’s not unexpected: Both can be released by burning vegetation.

But in 2025, 93% of sampled sites tested positive for measurable amounts of antimony and 84% for measurable amounts of manganese. A third of the 55 samples were above EPA-set maximum contaminant limits for antimony.

“Your heart kind of stops when you see something like that,” Zeigler said.

Mora County Commissioner Veronica Serna said she’s long been worried about water contamination following the fire.

“Our acequias were destroyed,” Serna said. “That is what recharges our private wells . ... Since the very beginning, I was concerned about our wells being contaminated by everything that burned upstream.”

The testing “confirmed my fears,” Serna said. Compounding those concerns is the repeated flooding of sediment into wells and acequias, which she worries will spread the contamination throughout the county — and potentially even beyond.

At the minimum, Serna would like to see filters provided to residents.

“I’m just concerned about the people that are probably closest to the burn scar, that are seeing the higher elevation of these heavy metals right now,” Serna said. “I am hoping they are avoiding consuming the water, although I understand that an occasional consumption of it isn’t as bad as long term.”

She added: “But I’d hate for them to take the chance.”

Found by accident

Antimony and manganese — which, according to the state

Health Department, can cause nausea, confusion and psychosis, cognitive impairment in youths and alter liver function — could be associated with fire retardants.

A 2024 article published in the Environmental Science and Technology Journal determined several metals, including antimony and manganese, were contained in long-term fire retardants sampled by researchers, possibly used as an anticorrosive agent. While the authors note the U.S. Forest Service must approve everything that goes into fire retardants, on public documentation, some pieces of the formulation are excluded as proprietary.

It can be difficult to determine the exact source of the contamination. The metals could come from fire suppressants, but also burned houses or trees that took up metal over time, Zeigler said.

“It is tricky to untangle,” she said.

The metals were detected by accident. Hoping to conserve limited funding for testing, the consulting firm planned to test for a truncated list of contaminants, focusing on those associated with burned organic materials like phosphate, nitrate and nitrite.

But the laboratory accidentally ran the samples for additional contaminants.

“Thank God that we messed up,” Zeigler said. “Because we never would have caught this metal spike the way that we did.”

Zeigler recommends Mora County residents avoid drinking their water until their wells can be tested. Filtration systems, including reverse osmosis and charcoal filter systems, could help, but its still being determined which systems might be the most effective, she said.

Zeigler hopes to determine where the Forest Service may have dropped fire suppressants while fighting the wildfire in 2022.

After compiling results from the 55 monitoring locations, the consulting firm has since added several new sites in areas that it believes were treated with fire retardants.

The state Department of Health is working with the state Environment Department and the state Department of Homeland Security and Emergency Management to conduct further testing and develop water treatment strategies.

Additional questions play on Zeigler’s mind: How could heavy metals bioaccumulate in livestock, fish and other wildlife? How long will they stay in the environment? What’s the impact on older burn scars?

“There’s so much that all of us, collectively, don’t know about how to deal with a fire this big and this catastrophic,” Zeigler said.