OSHA cites three companies after investigation into deadly gas exposure at Weld County dairy
WELD COUNTY, Colo. (KRDO) – The U.S. Department of Labor's Occupational Safety and Health Administration (OSHA) is citing three companies, proposing nearly $250,000 in fines after an investigation found that exposure to hazardous gas killed six workers at a Weld County dairy farm last year.
On Aug. 20, 2025, fire crews were dispatched to the Prospect Ranch in Keenesburg for a confined space rescue. When they arrived, personnel discovered six people dead at the scene, including one teenager.
The Weld County coroner's office ultimately determined all six people had died of hydrogen sulfide gas exposure. However, the autopsy reports gave little indication of the circumstances of those deaths, only describing an industrial accident in a confined space of the dairy farm.
In a news release on Tuesday, OSHA said its investigation discovered that on that day, a pipe in the manure management system at Prospect Ranch LLC disconnected, releasing manure water and hydrogen sulfide gas. Contractors Fiske Inc. and HD Builders LLC were subsequently hired to perform work on the system.
Investigators say a Fiske employee and a Prospect Ranch employee attempted to stop the flow, but were overcome by the gas. Three more Fiske employees and one Prospect Ranch employee then entered the pump room, and all six workers were killed by the hazardous gas.
OSHA said HD Builders employees were also there at the time, but were not hurt.
Federal regulators have now cited Prospect Ranch LLC for serious violations, including failure to protect workers from atmospheric hazards, lack of a written hazard communication program, and failure to train workers on methods to detect hazardous gases. The company faces $132,406 in proposed penalties, OSHA said.
Fiske Inc. was also cited for violations including failure to protect employees from hazardous atmospheres and failure to provide hydrogen sulfide detection training, with $99,306 in proposed fines against the company.
OSHA also cited HD Builders for violations including failure to have a written hazard communication program and failure to provide training on detecting hydrogen sulfide. The company is facing a $14,897 penalty.
According to federal regulators, the companies will have 15 business days to either comply, request an informal conference with OSHA, or contest the findings. Penalties and citations may be adjusted throughout the course of the case.
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