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An Extraction Oil & Gas oil drilling rig in operation on the Livingston pad on the west side of the Anthem neighborhood in Broomfield on Aug. 2, 2019. (Doug Conarroe, The Colorado Sun)

A new study shows that oil and gas drilling operations in Colorado may lead to short-term health impacts such as nausea, headaches and nosebleeds — a finding that is leading to calls for stricter regulations.

The report, commissioned by former Gov. John Hickenlooper’s administration and released Thursday, found that health risks are greatest during drilling and fracking of wells and that  emissions reach 2,000 feet from the drilling site. 

The results represent the worst-case scenario for exposure to benzene and other chemicals in hour-long periods. Benzene is a known human carcinogen, according to the Environmental Protection Agency. The report did not find a significant risk for longer-term health effects, and exposure to cancer-causing chemicals was within the acceptable range.

Colorado health officials cautioned that the worst-case conditions happen infrequently, but they could not say how often those conditions occur in areas near newer oil and gas operations. The potential for adverse effects is less likely near existing wells.

The new findings, first reported by The Colorado Sun, raise questions about whether the state’s current 500-foot buffer between homes and drilling operations is large enough to protect public health and reinvigorate a debate regarding Senate Bill 181 that dominated this year’s legislative session. 

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In response to the report, Gov. Jared Polis’ administration announced that it would “immediately enact stricter and safer review measures” when assessing applications permits for wells within 2,000 feet of buildings.

“This study reinforces how important the reforms of (Senate Bill) 181 are to put health and safety first and to empower local communities,” Polis said in a statement. “This modeling very clearly points to an urgent need for more real world testing on the actual air quality conditions at different distances in Colorado.”

Jeff Robbins, director of the Colorado Oil and Gas Conservation Commission, said his agency will “only approve any of those wells if we can ensure they will be protective” under the tougher new standards signed into law this year.

But a top lawmaker allied with the Democratic governor called for a tougher response. Senate Democratic leader Steve Fenberg said the state’s oil and gas regulators should stop issuing any permits for drilling within 2,000 feet of schools and buildings until rulemaking under the new law is finalized.

The Boulder lawmaker led the push for SB 181 earlier this year, which requires a greater focus on health and safety and more-stringent regulations on oil and gas operations in Colorado. He also plans to introduce legislation that will require additional air-quality monitoring and a thorough study about exposure to chemicals from drilling operations. 

“I am proud of the significant strides we made to protect the health and safety of Coloradans last session, but I recognize that there is always more work to be done and am committed to continuing the work,” Fenberg said in a written statement.

Oil and gas industry dismisses significance of report

The $600,000 study, conducted by consulting firm ICF, came from a task force created by the prior administration and began in 2017. A shorter version appeared online Thursday in the peer-reviewed Journal of the Air & Waste Management Association. It breaks new ground in Colorado, pairing emissions data collected in Weld and Garfield counties from 2014 to 2016 with meteorological data to create a statistical model that forecasts potential health impacts to people living near well pads ranging from one to five acres in size.

The full 380-page report issued by the state found that the highest levels of emissions and potential exposure come during the flowback period, when operators pump fluid at high pressure into shale to free oil and gas, and water, chemicals and hydrocarbons return to the surface. The flowback period can last as long as two weeks in Weld County and up to a month in Garfield County, according to the analysis.

Oil and gas activities have moved closer to neighborhoods in Colorado, including this Crestone Peak site known as the Pratt pad in Erie. (Doug Conarroe, The Colorado Sun)

Colorado Department of Public Health and Environment officials said that in more than 5,000 hours of field monitoring, they had never encountered levels as high as those projected by the models and such levels would need just the right weather conditions for the emissions to accumulate. 

Still, the modeling remains a concern, said John Putnam, CDPHE’s director of environmental programs. “In the air-quality world, we often regulate for those worst-case or close-to-worst-case scenarios.”

Children, the elderly and those with respiratory conditions are at highest risk. More study and better on-the-ground monitoring are needed to figure out how many people are exposed to the worst-case scenario, Putnam said.

Dan Haley, the president of the Colorado Oil and Gas Association, and other industry representatives dismissed the report’s findings, saying robust standards are currently in place that are not reflected in the report. Haley said drilling rigs operating now do not have emissions during the flowback process.

“This industry gets better every single day, and I truly believe we are doing it cleaner, better and safer than anywhere else,” he said.

New report leads Polis administration to take action

The Democratic administration, however, believes the new findings require prompt action, even before the new rules are finalized.

The state’s oil and gas commission is taking a harder look at permit applications for well locations within 1,500 feet of buildings. But the new data is leading regulators to extend that review to locations within 2,000 feet.

Polis also directed the CDPHE to develop and implement further testing to obtain better site-specific monitoring. 

The administration is walking a fine line when it comes to regulating the industry, pulled between those who want a moratorium on drilling and a $30 billion industry that is key to the state’s economy. 


Robbins, the state’s chief oil and gas regulator, pushed back against the need for a temporary moratorium until the new rules are drafted. He suggested that extending the current review to 2,000 feet is adequate.

“This study is suggesting to me, as director, that I should be precautionary (when reviewing) wells within that realm and we should take a hard look before we approve new wells within that realm,” he said, “and that’s exactly what we are doing.”

But Anne Lee Foster, who is with Colorado Rising, an organization that supports moratoriums on drilling, suggested the state is downplaying potential health effects and didn’t take into effect the cumulative effects of living near dozens of wells. 

“This only supports the fact that they need to pause the permits,” she said. “We are showing that harm is being done.”

State Sen. Ray Scott, R-Grand Junction, emphasized the limited scope of the projected health impacts and pointed to the economic factors if the industry is too over regulated. “Clearly, Gov. Polis was incorrect when he declared an end to the ‘oil and gas wars,’” Scott said in a statement, “as it seems his party is determined to tear down one of Colorado’s most economically beneficial industries.”

Staff writer Mark Jaffe contributed to this report.

John Frank is a former Colorado Sun staff writer. He left the publication in January 2021.