Department of Environmental Quality Trajectory Analyses of Class I areas in the Central and Western U.S. on 20% Worst Days Between 2011 and 2016 Department of Environmental Quality

Purpose & Methodology Performed back trajectories on active Class I sites in the western portion of the VISTAS domain. Purpose: Determine if these sites need to be analyzed further in work to complete Regional Haze SIPs among the VISTAS states. Methodology: 72-hour back trajectories ending at 10, 100, 300, 500, 750, 1000, 1500 and 2000 meters AGL. Using NAM 12km data. Looked at 20% worst days from 2011 to 2016. Data from IMPROVE website.

Texas

Oklahoma

Kansas

Nebraska

South Dakota

North Dakota

Minnesota

Montana

Wyoming

Colorado

New Mexico

Conclusions Sites in the following states do not need to be modeled or have Q/d analysis done: Colorado Wyoming Montana North Dakota South Dakota Nebraska Sites in the following states may need to be modeled or have Q/d analysis done: Texas Oklahoma Kansas Minnesota New Mexico