Wyoming Department of Environmental Quality (WDEQ)

EPA has classified Upper Green River Basin Area (UGRB), WY as Marginal Nonattainment for Ozone under the 2008 NAAQS Standard and includes Sublette County as well as portions of Lincoln and Sweetwater County.

Pollutant New Major Source Emission Rates Major Modification to existing Source
Nitrogen oxides (NOx) >0.1 tons/year >0.1 tons/year
Volitile Organic compounds (VOC) >0.1 tons/year >0.1 tons/year

To satisfy offset requirements, new or modified major facilities in nonattainment areas must obtain ERCs to satisfy the offset ratio requirements for proposed emission increases. The offset ratio for marginal nonattainment area for ozone is 1.1 to 1. That means if 100 tpy of VOCs are emitted from a proposed new or modified major facility in the UGRB the facility must obtain 110 tpy of ERCs to offset the increase in NOx emissions.