Board seeks court review of EPA ozone designation

Published on December 16, 2021

The Weld County Board of Commissioners

Yesterday, the Weld County Board of Commissioners petitioned the U.S. Court of Appeals for the D.C. Circuit to review the U.S. Environmental Protection Agency’s (EPA) final decision to move the ozone nonattainment area boundary for the 2015 ozone standards to include all of rural northern Weld County. In July, the Board submitted lengthy comments to EPA that demonstrate through in-depth technical analyses that the best available data do not support EPA’s decision to move the boundary.  The Board’s detailed comments also demonstrated the lack of data indicating contributions to ozone violations from sources in northern Weld County.  Those comments and technical analyses are available at:

In this lawsuit, the Board intends to show the EPA’s decision is unfounded. The EPA failed to consider the most recent four plus years of available monitoring and weather data and ozone photochemical modeling results in making its recent boundary designation. In addition, the EPA selectively removed certain data from its technical support documentation, relied on monitoring data that was wildfire-smoke-influenced, and failed to carefully conduct the required five-factor analysis before deciding to move the non-attainment boundary for the 2015 ozone standards.  Board Chair Steve Moreno noted that “if EPA’s designation decision goes unchallenged, it will impose upon rural northern Weld County all manner of regulatory measures designed for the Denver urban and suburban core for decades to come and will result in no air quality benefits.” The case is captioned Board of County Commissioners of Weld County, Colorado v. Michael S. Regan, Administrator, Environmental Protection Agency, and United States Environmental Protection Agency.  The Board is represented in this matter by John Jacus, Shannon Stevenson, and Kathleen Pritchard of Davis Graham & Stubbs LLP and Ethan Schenkman of Arnold & Porter Kaye Scholer LLP.

Case number for the appeal is No. 21-1263.