A Garfield County official said it is up to the Colorado Oil and Gas Conservation Commission to investigate reports that hydrogen sulfide gas, which experts say can cause severe respiratory problems and even death, is showing up at natural-gas drilling operations in this region.

“It's an oil and gas issue,” said Garfield County Environmental Health Manager Jim Rada, when asked about an Aug. 4 report in the Grand Junction Daily Sentinel that the Noble Energy natural gas company had encountered the gas during drilling operations.

State officials at the Colorado Oil and Gas Conservation Commission (COGCC) said on Friday that they are looking into the report, and plan on presenting their findings to the commission at a meeting today in Denver.

The appearance of hydrogen sulfide during gas drilling operations is not necessarily a new issue, Rada said.

“Hydrogen sulfide has been an issue with reserve tanks and pits in the past,” he said, referring to equipment and facilities commonly found in association with oil and gas drilling operations.

According to the news report, Noble Energy, which is operating in Garfield County, has regularly encountered the gas during drilling operations.

In one instance in 2009, Silt Mesa resident Carl McWilliams grew ill after inhaling the gas while working for a contractor at a Noble Energy drilling site in Garfield County.

The incident resulted in a complaint by McWilliams to the Occupational Safety and Health Administration, which fined McWilliams's employer, Lonkar Services (USA) $2,000 for violating worker safety rules while doing contract work for Noble.

Nobel reportedly confirmed that since that incident, its drilling crews have regularly encountered hydrogen sulfide at relatively minor levels.

This runs counter to industry and government statements that hydrogen sulfide is only rarely found in the Piceance Basin gas fields, which include much of Garfield County.

According to the U.S. Centers for Disease Control, hydrogen sulfide, or H2S, is a hazardous and toxic gas that, when inhaled, can cause severe respiratory distress, headaches, loss of motor control and memory and other human malfunctions. It is produced when certain bacteria consume sulfur-bearing organic matter.

At concentrations below 30 parts per million (ppm) is puts off a smell like rotten eggs. At 100 ppm or more, it can paralyze the olfactory nerve and cause a loss of the sense of smell.

Exposure at increasing concentrations can cause nausea and vomiting, difficulty breathing, shock, convulsions and death in the most severe cases.

“Deaths due to breathing in large amounts of hydrogen sulfide have been reported in a variety of different work settings, including sewers, animal processing plants, waste dumps, sludge plants, oil and gas well drilling sites, and tanks and cesspools,” stated the CDC's Agency for Toxic Substances and Disease Registry.

Attempts to reach Noble Energy in Denver were not successful on Friday.

One alleged case of H2S toxicity occurred earlier this year when a Silt Mesa family, the Strudleys, reported smelling rotten eggs in their home, which was close to a drilling rig operated by Antero Resources.

A June 15 air sample, taken by volunteers in a Bucket Brigade community monitoring effort, reported finding hydrogen sulfide gas in the Strudley home at high concentrations.

The Global Community Monitor group reported the gas occurred at 185 times the level set by the Environmental Protection Agency as posing long-term health risks to humans.

Dave Neslin, director of the COGCC, said he is searching the agency's archives to determine if it has gotten reports from Noble or other drilling companies regarding the appearance of hydrogen sulfide.

Rule 607 in the COGCC regulations states, “any gas analysis indicating the presence of hydrogen sulfide gas shall be reported to the Commission” and to the local government.

Phone calls on Friday to the Garfield County oil and gas liaison office, seeking comment on this story, were not answered.

jcolson@postindependent.com