Species Specific Reasonable Progress Analysis Page Species Specific Reasonable Progress Analysis August 30, 2006 WRAP IWG Meeting Portland, Oregon Presented by: Ray Mohr and Curt Taipale

Colorado Proposed RP Approach Page 2 Colorado Proposed RP Approach Reasonable Progress should be demonstrated on a pollutant-by-pollutant basis. If the regional modeling shows little improvement in meeting URP for a given CIA, then the following analysis approach is proposed: Given the constraints imposed by the modeling and the uncertainty of anthropogenic (OC, EC, Soil & CM) source strength, limit the detailed RP analysis to only sulfate and nitrate. The anthropogenic portions of OC & EC could be addressed in the LTS under a comprehensive analysis for smoke management. Similarly, the anthropogenic portions of Soil & CM could be addressed in the LTS under a comprehensive analysis for construction activities. Determine the sulfate and nitrate contribution of anthropogenic sources in 2002 and 2018 (using PSAT).

Colorado Proposed RP Approach (Cont.) Page 3 Colorado Proposed RP Approach (Cont.) Divide the reduction over the 5 periods (number of SIP planning periods before 2064) equally to establish a 20% reduction goal for the first planning period. Thus, a 20% reduction from manmade sources of sulfate and nitrate could be the progress goal for each CIA. For each State, the percentage of sulfate & nitrate attribution for each CIA could be compared with the State’s 2018 SO2 and NOx reduction from baseline to see if the 20% goal is met (e.g. State sulfate impact = 40%, State SO2 reduction responsibility: 20% x 40% = 8%). Direct interstate coordination of sulfate and nitrate attribution could be limited to the top 3-4 surrounding states impacting each CIA. The remaining states likely have a relatively minor sulfate and nitrate impact on each CIA and the accumulated reduction responsibilities are probably < 2-3%. Examination of the 4 statutory factors (costs, time & impacts of compliance and remaining useful life) would be required to determine if the progress is “reasonable”.

Page 4

RP - Other Issues International Impacts (deduct from goal?) Page 5 RP - Other Issues International Impacts (deduct from goal?) Data variability (from non-anthropogenic sources)

International Impacts Page 6 International Impacts International impacts inflate URP and the 2018 goal. These impacts will likely change in the future and could add to the RP burden. Reduction of these impacts are not the responsibility of states.

Page 7 Data Variability Over 6 deciviews of variation in data. The worst day baseline is skewed high from historical average due to wildfires during the baseline period. Since wildfire has inflated the baseline worst days, the URP is higher and the 2018 goal is more challenging

SO4 “Other” category = 10% NO3 “Other” category = 13%