Six Workers Die From Hydrogen Sulfide at a Colorado Dairy Farm as Rescuers Become Victims
DENVER — One disconnected pipe at a Colorado dairy farm set off a chain reaction that killed six workers — most of them trying to save each other. On February 24, 2026, OSHA cited three companies after its investigation into the hazardous gas exposure at Prospect Ranch in Weld County.
The Incident
On August 20, 2025, 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 had been hired to perform work on the system. A Fiske employee and a Prospect Ranch employee attempted to stop the flow and were overcome by the gas. Then three more Fiske employees and another Prospect Ranch worker entered the pump room after them — and were overcome too. In total, six workers lost their lives.
It is the grimmest pattern in confined space and toxic gas incidents: would-be rescuers rushing in unprotected, multiplying a single casualty into a mass fatality.
The Investigation
OSHA cited Prospect Ranch LLC for serious violations including failure to protect workers from atmospheric hazards, failure to have a written hazard communication program, and failure to train workers on methods to detect hazardous gases. The farm faces $132,406 in proposed penalties.
Fiske Inc. was cited for serious violations including failure to protect employees from hazardous atmospheres and failure to provide hydrogen sulfide detection training, drawing $99,306 in proposed penalties. HD Builders, whose employees were present but unharmed, was cited for lacking a written hazard communication program and hydrogen sulfide detection training, with a proposed penalty of $14,897.
The companies have 15 business days from receipt of their citations to comply, request an informal conference with OSHA, or contest the findings before the independent Occupational Safety and Health Review Commission.
Lessons to Take Home
Hydrogen sulfide is invisible, heavier than air, and deadens your sense of smell at high concentrations — by the time you realize something is wrong, you may already be going down. Anywhere organic material decomposes, from manure pits to sewers, the gas must be treated as a killer. That means atmospheric testing before entry, gas detection training for every worker on site, and a written program that spells out the hazards of the chemicals around them.
Above all, drill this into your crew: never enter after a downed co-worker without proper equipment. The instinct to help is exactly what killed four of the six workers here. Stopping and calling for a proper rescue is not cowardice — it is the response that keeps one victim from becoming six. That discipline starts with a culture where anyone can halt a job, so make our stop work authority talk part of your next safety meeting.
