1. SO 2 Data Analysis The following 4 slides attempt to provide a context for a re-analysis of the model results using the milestone inventory. If model results show a reduction in sulfate on the Colorado Plateau on the 20% worst (modeled) days, those results could be added to the slide show to complete the picture. Slide 1: 1990 – 1999 Improve data, 20% worst days Pie chart: Average contribution to extinction of selected components over 10 years Bar chart: SO 4, variance from the mean at individual stations over the same time period Slide 2: A comparison of OC and SO 4 as a percentage of B ext, and their correlation to emissions from wildfire. Slide 3: A qualitative relationship between observed sulfate on the Colorado Plateau and the 1996 WRAP modeling inventory for the 9 transport states (without fugitive dust). Slide 4: Comparisons between the 1996, 2018 base, and 2018 milestone inventories for point source SO 2 in the 9-state region. A 32% reduction in electric utility SO 2 in the milestone inventory yields a 21% reduction in total point source SO 2 in the region. Sources: Improve: Annual Light Extinction Group 10, 50, 90 http://vista.cira.colostate.edu/DatawareHouse/IMPROVE/Data/SummaryData/RECONBEXT_annual.TXT Projections Report for the 2018 Base Case Emission Inventory Pechan, May 2002 on WRAP emissions forum page Spreadsheets for various inventory components located on the WRAP Emissions Forum page Interagency situation reports for U.S. wildfires. http://www.nifc.gov/news/nicc.htmlhttp://www.nifc.gov/news/nicc.html Patrick Barickman Colleen Delaney Brock LeBaron Utah DAQ August, 2002

2. Components of Visibility Degradation on the Colorado Plateau 1989 – 1999 as Measured at 6 Locations ( 20% Worst Days ) Variation in Sulfate Contribution to Visibility Degradation During the 20% Worst Days 1989 - 1999

3. Correlation between wildfire intensity and the SO 4 /OC contribution to B ext on the Colorado Plateau. SO 4 OC

4. 1996 Inventory - 9 Transport States, All Sources 1996 SO 2 Inventory Components of Visibility Degradation on the Colorado Plateau 1989 – 1999 as Measured at 6 Locations ( 20% Worst Days )

5. 17% Reduction in Point Source SO 2 From 1996 to 2018 Base Year Point Source SO2 – 1996, 2018 Base Year, 2018 Milestone 21% reduction in Point Source SO 2 From the 2018 Base Year to the 2018 Milestone Inventory Reduction in Electric Utility SO 2 = 32%