Colorado air pollution regulators miscalculated oil and gas emissions

Colorado air pollution regulators are withdrawing portions of their plan to improve the Front Range’s smog problems because they made significant errors in calculating oil and gas emissions, yet state health officials still want the rest of the proposal sent to the Environmental Protection Agency for approval.

The state’s Air Pollution Control Division issued a notice last month saying its new calculations predict the estimates of emissions of nitrogen oxide for drilling and fracking operations are nearly double what was originally reported in the plan, according to a 10-page notice posted with the Air Quality Control Commission’s December meeting agenda.

The commission’s meeting begins Tuesday and includes three days of public hearings over the so-called State Implementation Plan, an outline for improving air quality that is required under the federal Clean Air Act because Colorado is out of compliance with national air quality standards. The commission is expected to vote Friday on whether to accept the plan and send it to the EPA.

Trisha Oeth, director of environmental and health protection for the Colorado Department of Public Health and Environment, said the agency will ask the commission to postpone a decision on the flawed parts of the plan but to approve the rest of it, including recommendations for pushing Colorado towards its clean air goals.

“All the things that were proposed are still on the table,” Oeth said. “There’s no delay on actual air quality improvements.”

The errors, first reported by Colorado Public Radio, were discovered in November when industry estimates on emissions submitted to the Colorado Oil and Gas Conservation Commission did not match calculations in the State Implementation Plan, according to the withdrawal notice. The plan was originally written by the Regional Air Quality Council with data from the state health department’s Air Pollution Control Division.

State officials let Air Quality Control Commission members, environmentalists, industry representatives and others know as soon as the mistake was discovered, Oeth said.

The emissions calculations included in the State Implementation Plan were derived from 2017 industry data on nitrogen oxide and volatile organic compounds released during oil and gas drilling. However, the numbers were erroneously divided by the number of new wells drilled in 2017 rather than the total number of all wells associated with the reported emissions.

“This generated artificially low emission factors,” the withdrawal notice said.

The state’s Air Quality Control Division plans to dig into the numbers again in early 2023 and create a better analysis. Then a public hearing will be held on the new findings, Oeth said.

In September, the EPA designated Denver and Colorado’s northern Front Range as severe violators of the nation’s clean air standards. That label means motorists will pay higher gas prices in the summer because the region will be required to switch to a special blend of gasoline, and more businesses will face tougher air pollution regulations, including the need to apply for federal air permits.

The state has actually missed two Clean Air Act standards and is struggling to catch up.

The severe designation came after years of failing to meet a 2008 rule that required states to reduce ozone emissions to 75 parts per billion annually. State air regulators believe Colorado is on track to meet that goal by 2027 even with the error made in calculating oil and gas emissions, Oeth said.

However, the state will miss its deadline for reaching the 2015 ozone emissions standard of 70 parts per billion by 2024.

Sorting out the various air quality standards and the deadlines to reach them can be confusing. Because Colorado has failed for so many years to reach the 2008 standard, the state keeps getting new deadlines to reach it while facing consequences such as the “severe non-attainment” label it was given in September. Meanwhile, the state is also on the hook for the more stringent 2015 requirements.

That’s one reason state officials are recommending the Air Quality Control Commission approve most parts of the air quality improvement plan while calling for a do-over on the oil and gas emission calculations, Oeth said. Regulators already know they’re going to miss the 2024 deadline but also recognize they have another two years to get their calculations correct for meeting the more lax 2008 standard.

David Sabados, spokesperson for the air quality council, said the state should reach the 2008 standards despite the error.

“It’s significant enough that we support CDPHE going back to look at the data, but it’s an error in one part of one industry’s contribution to ozone levels,” he said.

But critics of the plan continue to call for the commission to do more.

“Right off the bat, the division’s (State Implementation Plan) showed we wouldn’t meet the (2015) deadline,” said Caitlin Miller, senior associate attorney in EarthJustice’s Rocky Mountains office. “That alone violates the Clean Air Act.”

Miller and other environmental advocates said they appreciate the state’s transparency in admitting it made an error in calculating oil and gas emissions and by notifying the public it happened.

But state regulators for years have predicted they would meet air quality standards only to fall short and now there’s a known error in the calculations. The state very well could be on track to again fail to meet the 2008 standard, Miller said.