Federal workplace safety regulators penalized three businesses Tuesday over their failure to protect six Colorado dairy workers who were killed by exposure to highly toxic hydrogen sulfide gas after a manure pipe disconnected in an enclosed space.
The U.S. Occupational Safety and Health Administration announced proposed fines totaling $246,609 against the dairy owner and two contractors working on a manure management system. The deaths of five men and a teenager
on Aug. 20, 2025, shocked the rural communities in and around Keenesburg, 35 miles (55 kilometers) northeast of Denver.
Dairy owner Prospect Ranch LLC, which did not immediately respond to a request for comment, faces the largest fine at $132,406 for serious violations, including failures in training, planning and protecting workers from “atmospheric hazards.”
Regulators also announced proposed fines against Colorado-based Fiske Inc. and another contractor hired to work on the system that released manure water and the hydrogen sulfide gas that led to the deaths, the government said Tuesday in a news release.
Fiske Inc.'s business High Plains Robotics services dairy equipment and employed four of those who died. Fiske faces $99,306 in penalties for failing to protect employees and provide hydrogen sulfide detection training.
“A Fiske employee and a Prospect Ranch employee attempted to stop the flow but were overcome by the gas,” OSHA said in the statement. “Subsequently, three more Fiske employees and one Prospect Ranch employee entered the pump room, which led to the loss of a total of six workers."
The Weld County coroner’s office determined from autopsies and toxicology tests that the people who died were exposed to hydrogen sulfide gas, but provided little indication of the circumstances of the deaths, describing only an industrial accident in a confined space at a dairy farm.
Contractor HD Builders was cited for failing to have a written hazard communication program and provide training on detecting hydrogen sulfide, with a proposed $14,897 penalty. Company employees were present but unharmed after the pipe disconnected.
The companies have 15 days to comply with proposed penalties, request an informal conference with safety regulators or challenge the findings before an occupation safety review commission.
Fiske Inc. and company owner Kevin Fiske said in a statement Tuesday that “our hearts are heavy as we review OSHA’s citations.”
“We have cooperated with the investigation proceedings to date,” Fiske said. “While we disagree with the findings and are reviewing our options to determine next steps, we are focused on doing what is in our power to ensure that a tragedy like this never happens again.”
A representative for HD Builders said Tuesday that the company had no comment.
The hazards of confined spaces on farms and dairies are a well-known and persistent cause of death in agriculture across the U.S. — often from exposure to odorless and colorless noxious gases, or due to asphyxiation in closed spaces where oxygen has been depleted.
First responders from a rural fire district in Weld County were dispatched around 6 p.m. on Aug. 20 to Prospect Ranch and took their own safety precautions as they entered a confined space.
All those who died in Colorado were Latino, ranging in age from 17 to 50. Four of them, including the teenage high school student, were from the same extended family and worked for Fiske Inc.'s High Plains Robotics.
Alejandro Espinoza Cruz, of Nunn, was found dead along with his 17-year-old son Oscar Espinoza Leos and a second son, 29-year-old Carlos Espinoza Prado.
The Espinozas are related by marriage to a 36-year-old from Greeley who died — Jorge Sanchez Pena, according to the Weld County coroner’s office.
The other two men — Ricardo Gomez Galvan, 40, and Noe Montañez Casañas, 32 — lived in Keenesburg.
The remains of Montañez Casañas, a veterinarian who was employed under a U.S. visa, were repatriated to the central Mexican state of Hidalgo, according to the Mexican consulate in Denver.
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Lee reported from Santa Fe, New Mexico.
