Coroner’s report on 6 deaths at Colorado dairy points to toxic gas exposure
Authorities confirmed that six people who died at a Colorado farm earlier this year were exposed to hydrogen sulfide gas. Denver7
WELD COUNTY, Colo. — Authorities confirmed Thursday that six people who died at a Colorado dairy farm in August were fatally exposed to hydrogen sulfide gas, a colorless but deadly chemical often produced by decomposing manure.
The Weld County Coroner’s Office announced that autopsies and toxicology tests determined the victims — five men and one teenager — succumbed to the toxic fumes while working at Prospect Ranch, a large-scale dairy operation about 35 miles northeast of Denver in Keenesburg.
The August 20 tragedy shocked the local farming community, prompting immediate concern among emergency responders that the victims had been overcome by hazardous gases inside a confined workspace.
Federal workplace safety investigators are now reviewing the coroner’s findings as part of a broader investigation into what went wrong at the dairy, which is owned by California-based Prospect Ranch. OSHA is also examining the role of Johnston, Colorado-based Fiske Electric and its subsidiary High Plains Robotics, which serviced dairy equipment and employed some of the victims.
Autopsy reports described the incident as an “industrial accident” inside a confined space but offered no further details about the sequence of events. Both federal and local authorities have released limited information while the investigation continues.
Confined spaces — such as silos, manure pits, and storage tanks — are known to be among the most dangerous work environments in agriculture. Workers can quickly be overcome by invisible, odorless gases like hydrogen sulfide, methane, and carbon dioxide, or suffocate when oxygen is depleted.
All six victims were Latino men between 17 and 50 years old. Four were members of the same extended family.
Those who died were identified as:
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Alejandro Espinoza Cruz, of Nunn
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Oscar Espinoza Leos, 17, and his brother Carlos Espinoza Prado, 29, both of Evans
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Their relative Jorge Sanchez Pena, 36, of Greeley
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Ricardo Gomez Galvan, 40, of Keenesburg
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Noe Montañez Casañas, 32, also of Keenesburg, a veterinarian working in the U.S. on a visa. His remains were returned to Hidalgo, Mexico, according to the Mexican Consulate in Denver.
In the days following the tragedy, the close-knit Keenesburg community came together to support the victims’ families. Fundraisers included car washes, dances, and haircut drives, while local churches held a memorial service featuring hymns like Amazing Grace.
“People are in shock,” said Rev. Thomas Kuffel of Holy Family Catholic Church in Keenesburg. “Everyone knows farm work is hard and dangerous, but losing six people at once is something this community has never experienced.”
Experts say confined-space deaths are preventable with proper training and safety planning. Purdue University agricultural safety specialist William Field explained that emergency procedures — including oxygen monitoring, ventilation, and protective breathing equipment — are essential.
“Having an emergency action plan can stop a chain reaction of tragedy,” Field said. “You don’t want a situation where one person collapses and others rush in unprotected.”
Hydrogen sulfide, the gas identified in the coroner’s report, is especially dangerous. Though it has a “rotten egg” odor, the smell quickly becomes undetectable at high concentrations — a condition known as olfactory fatigue — leaving workers unaware they’re in danger.
OSHA investigations can take months, and due to the ongoing federal government shutdown, officials have not provided updates or responded to inquiries about the case.
Under federal labor laws, agricultural workers as young as 16 can legally perform hazardous work — a rule that does not apply in most other industries. Experts like Renée Anthony, director of the Great Plains Center for Agricultural Health, say the absence of specific safety standards for confined spaces in agriculture leaves many workers vulnerable.
“All employers, including in agriculture, have a legal responsibility to protect workers from recognized hazards,” Anthony said. “Tragedies like this show why stronger safeguards are urgently needed.”
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