A hydraulic fracturing site in Weld County on November 18, 2011. Boulder County is monitoring oil and gas emissions wafting in from its neighboring county. Credit: James Wengler

As residents in Colorado’s Front Range prepare for the summer’s unhealthy ozone levels, Boulder County officials are pointing blame for the region’s air quality woes at the oil and gas industry. 

In a presentation to the state Air Quality Control Commission on Thursday, July 21, the county’s air quality experts presented studies they’ve commissioned on oil and gas pollution wafting in from drilling sites in Weld County. That pollution includes volatile organic compounds (VOCs) and methane, a potent planet-warming gas. Much of the research is based on data collected by an air monitor at the Boulder Reservoir that was installed in 2017. 

The new research indicates oil and gas emissions are the single largest contributor to ground-level ozone, one of the Front Range’s most urgent public health threats. Ozone forms when VOCs and other pollutants from oil and gas, wildfires and automobiles react with sunlight. The toxic gas is linked to respiratory ailments, heart attacks and strokes.

The studies bolster earlier research showing the oil and gas industry’s outsized contribution to ozone concentrations. The county also presented data indicating methane emissions have not declined in recent years — despite efforts to rein in the greenhouse gas. 

“Despite newer regulations, oil and gas emissions have not decreased,” said Cindy Copeland, Boulder County’s air and climate policy adviser. 

Boulder County has a long history of fighting against oil and gas drilling. In 2012, the county passed its first drilling moratorium. The moratorium ended in 2016, when the Colorado Supreme Court stuck down such local bans. The county borders Weld County, which produces more oil and gas than any other county in Colorado. Both counties sit atop the oil- and gas-rich Denver-Julesburg Basin. 

In addition to Boulder County, the City of Longmont, Town of Erie and the City and County of Broomfield have commissioned their own emissions monitoring to better understand the impacts of drilling on public health. 

By putting the spotlight on oil and gas drilling, the local governments hope the nine-member Air Quality Control Commission will crack down on industry emissions in order to curb ozone and greenhouse gas pollution. 

Specifically, they want state air quality regulators to adopt rules prohibiting drilling during the summer ozone season, according to Copeland. The local governments also want more stringent regulations on flaring, a process where operators burn off gas emitted from wells, she said. 

The northern Front Range has been out of compliance with federal ozone standards for nearly two decades. The state issued a record-setting 65 ozone alerts in 2021, the year it was supposed to come into compliance with the Clean Air Act. It is now working on a plan to address ozone pollution that the Air Quality Control Commission is scheduled to consider in December. 

In the past, to get extra time to comply, the state has cited out-of-state emissions and wildfire smoke as key sources of its ozone problem, suggesting it was outside its control. That was one of the reasons Boulder County commissioned a study on the role of wildfires in Front Range ozone. 

That research, published in 2021 and based on data collected from 2017 to 2019 at an air monitoring station at the Boulder Reservoir, indicates VOCs from drilling are the primary drivers of ozone — not wildfires. 

“Most of the time, our VOCs are predominantly from oil and gas production,” Bill Hayes, air quality coordinator at Boulder County Public Health, told the commission. “The majority of high ozone days were not significantly impacted by wildfire smoke.”

The study was done by Colorado State University’s Department of Atmospheric Science and Boulder A.I.R, which is headed by Detlev Helmig, a scientist who contracts with Boulder County to collect data from the monitor at the Boulder Reservoir. 

‘What we found was surprising and concerning.’

Local officials also sought to highlight the role of oil and gas in methane emissions. Methane is a potent greenhouse gas that doesn’t live as long in the atmosphere as carbon dioxide, but has a greater planet-warming effect in the short term.  

For years, the state has chipped away at methane emissions from oil and gas drilling. Notably in 2014, it adopted the nation’s first regulations to limit emissions of methane. In 2019, regulators enacted new rules to reduce methane leaks from gas lines, storage tanks and other drilling infrastructure. 

In opposing more aggressive measures, the oil and gas industry cited data last year showing methane emissions are dropping across the Front Range. (Weld County has cited similar data in presentations to state regulators.) 

Building on a 2021 peer-reviewed study, the data from the Boulder Reservoir indicates methane emissions from oil and gas wells have not declined in a statistically significant way since at least 2017, when the monitor was installed. The yet-to-be released research was conducted by Helmig and others. Helmig told Boulder Reporting Lab the study has been submitted for peer review. 

In 2019, Helmig was commissioned by the City of Longmont to monitor the air at the Union Reservoir. During the meeting on Thursday, Jane Turner, Longmont’s oil and gas and air quality program manager, presented data from the monitoring program indicating methane pollution is drifting over from Weld County. 

“What we found was surprising and concerning,” Turner said. “The methane concentrations that we’re seeing in Longmont were many times greater than was observed at Boulder Reservoir. We routinely record plumes of very high concentrations of methane blowing into the city.” 

Several of Longmont’s monitors collect data every five seconds, 24 hours per day. Officials said some of the state’s data, by contrast, “is not a good representation” of oil and gas emissions because it is not continuous and therefore misses spikes in methane. (In a July 2022 presentation, the state Air Pollution Control Division cited data from an air monitor in Platteville that operates from 6 a.m. to 9 a.m. The divisions cited data from the monitor to suggest ozone-causing emissions from oil and gas production in the Front Range are decreasing.)

Separately, in the Town of Erie, officials set up an air monitor at Kenosha Farms in order to measure background concentrations of methane and other pollutants. The monitor was maintained by Ajax Analytics, a Fort Collins-based environmental research firm, and Colorado State University. 

The monitor was as far away from any wells as town officials could find, according to David Frank, the town’s energy and environmental program specialist. But in February this year, the monitor recorded a spike in methane concentrations due to a leak in a gathering line about 700 feet from the monitor, roughly equivalent to the length of two football fields. 

“This shows how much impact even a fairly routine pipeline leak, which we see all too frequently, can have on nearby residents,” Frank said. 

Mindy Olkjer, an oil and gas program manager for the City and County of Broomfield, presented research from a study conducted by Broomfield in partnership with the University of Colorado School of Public Health. 

Collecting health data from 427 Broomfield residents from October to December of 2021, it found adults living within one mile of a drilling site reported significantly greater frequencies of upper respiratory issues and acute health symptoms than residents living two miles from a drilling site. Symptoms include nausea, vomiting, nosebleeds, lung irritation, shortness of breath, coughing, throat irritation

Overall, there was a sense of urgency from the officials. 

“We local governments have valuable data and that it needs to be considered alongside data from [Colorado Department of Public Health] and industry,” Copeland said. “One reason for that is because of the health impacts to our residents.”

John Herrick

I report on housing, climate, health and local government for the Boulder Reporting Lab. I previously covered the state Capitol for The Colorado Independent and environmental policy for VTDigger.org. I’m interested in stories about people, power and fairness.

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