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Public Notice of Exceptional Events - Uinta Basin of Utah

The Ute Indian Tribe of the Uintah and Ouray Reservation operates ozone monitors at four locations, Myton, Whiterocks, Ouray and Redwash. These four monitors recorded their highest and second highest 8-hour ozone in 2015 on June 8 and 9. Data presented in the Technical Support Document (TSD) show that the high ozone recorded on those days was unseasonably high, not consistent with historical readings and patterns, and that they coincided with the intrusion of stratospheric air into the troposphere contributing ozone to the surface measurements. With this demonstration, the Ute Indian Tribe is requesting that the EPA concur on stratospheric ozone exceptional event flags the tribe has applied to the impacted data in the Air Quality System database, and that the EPA exclude the exceedances caused on June 8 and 9, 2015 by stratospheric intrusion from calculations of ozone exceedances and violations for 2015.

Submit Comments

Please submit your comments by September 29, 2016. All comments should be addressed to Richard Payton, U.S. EPA, Region 8, Air Program (8P-AR), 1595 Wynkoop Street, Denver, CO 80202 or at

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