Technical Support Document -SupplementalThis Technical Support Document (TSD)evaluates Colorado’s impact to visibility in nearbyoutand organic carbon. The Western Regional AirPevaluation of state source attribution: (1)PM Source Apportionment Technology (PSAT) modelingandPotential (WEP).These analysis tools were applied to the Class I areas that are indicated by a yellow dot in Figure 1below.TSD, the PSAT and WEP analysis tools, along with a review ofapproach (WOE) to determine whetheremissions fromreasonable progress goals (RPG) under the RegionalHaze program.Figure 1. Nearby Class I Areas Evaluated with PSATand WEPThe WRAP analyses show that Canyonlands National Park is the Class I area where visibColorado. Therefore, the WOE information providedin this TSD focuses primarily on Canyonlands with the knowledge that impacother nearby Class I areas will be less.The PSAT and WEP analysis tools are summarSupplementalWeight-of-Evidence (WOE)the 110 Transport SIPevaluates Colorado’s impact to visibility in nearbyout-of-state Class I areas for sulfate, nitratePartnership (WRAP) has produced the following twoanalysis toolsPM Source Apportionment Technology (PSAT) modelingand(2)These analysis tools were applied to the Class I areas that are indicated by a yellow dot in Figure 1below.is tools, along with a review ofcurrent and future year inventories, are used inemissions fromColorado sources interfere with theability of nearby States to meet theirreasonable progress goals (RPG) under the RegionalHaze program.Figure 1. Nearby Class I Areas Evaluated with PSATand WEPThe WRAP analyses show that Canyonlands National Park is the Class I area where visibility is most impacted by emissions fromColorado. Therefore, the WOE information providedin this TSD focuses primarily on Canyonlands with the knowledge that impacThe PSAT and WEP analysis tools are summarized below.Evidence (WOE)Analysis Supportingstate Class I areas for sulfate, nitrateanalysis toolsfor use in the(2)Weighted EmissionsThese analysis tools were applied to the Class I areas that are indicated by a yellow dot in Figure 1below.In thiscurrent and future year inventories, are used ina weight-of-evidenceability of nearby States to meet theirility is most impacted by emissions fromColorado. Therefore, the WOE information providedin this TSD focuses primarily on Canyonlands with the knowledge that impacts toPage 2(1) PSAT:The Regional Modeling Center (RMC) at the University of California – Riverside developed the PSAT algorithm in the ComprehensiveAir quality Model with extensions (CAMx) model to assess source attribution. The PSAT analysis is used to attribute particle species,particularly sulfate and nitrate from a specific location within the WRAP modeling domain. The PSAT algorithm applies nitrate-sulfateammonia chemistry to a system of tracers or “tags”to track the chemical transformations, transport and removal of emissions. Eachstate or region (i.e. Mexico, Canada) is assigned aunique number that is used to tag the emissions from each 36-kilometer grid cellwithin the WRAP modeling domain. Due to time and computational limitations, only point, mobile, areaand fire emissions were tagged.The PSAT algorithm was also used, in a limited application (e.g. no state or regional attribution), totrack natural and anthropogenicspecies of organic aerosols at each Class I area.The organic aerosol tracer tracked both primary andsecondary organic aerosols(POA & SOA). In 2007, the WRAP RMC performed two modeling runs using the 2002 planning inventory (plan02c) and the 2018 basecase inventory (base18b) for which PSAT analysis was completed. In the spring of 2009, the WRAP released an updated 2002planning inventory (plan02d) and the 2018 preliminary reasonable progress inventory (prp18b), but unfortunately no PSAT analysis wasdone due to insufficient funding. It is importantto note that the PSAT results used in this analysisare derived from the base18binventory and not the subsequent prp18b inventory.(2) WEP:The Weighted Emissions Potential analysis (WEP) wasdeveloped as a screening tool for states to decidewhich source regions havethe potential to contribute to haze formation at specific Class I areas, based on both the 2002 and 2018 emissions inventories. Thismethod does not produce highly accurate results because, unlike the air quality model and associated PSAT analysis, it does notaccount for chemistry and removal processes. Instead, it relies on an integration of gridded emissions data, back trajectory residencetime data, a one-over-distance factor to approximate deposition, and a normalization of the final results. Residence time over an areais indicative of general flow patterns, but does not necessarily imply the area contributed significantly to haze at a given receptor.Therefore, users are cautioned to view the WEP as one piece of a larger, more comprehensive weight ofevidence analysis. Note that,unlike the PSAT analysis, the WEP results were produced for the PRP 2018b emission inventory upon which RPGs are based.PSAT Evaluation of Colorado Impacts on nearby ClassI areas:For each Class I area over the planning period, theRegional Haze rule requires States to ensure no degradation in the least impaireddays (best days) and provide for improvement in visibility for the most impaired days (worst days). The State must also establish goalsthat provide for reasonable progress towards achieving natural visibility conditions. Consequently, the impacts associated with the2018 worst days are evaluated to see if further improvement can be achieved. While the Regional Hazerule also requires States toensure no degradation of visibility on the best days, the WRAP modeling projects that visibility on the best days will not degrade in 2018at any of the surrounding Class I areas. For example, modeling indicates that the visibility at Canyonlands National Park on the bestdays is expected to improve from 3.8 dv to 3.5 dv.Therefore, this TSD focuses on analysis of the worst days.Page 3Table 1 shows Colorado’s contribution to sulfate and nitrate extinction on the worst days at nearby Class I areas for the plan02c andbase18b modeling scenarios. In 2002, the largest contributions from Colorado, 3.4% for sulfate and 6.9% for nitrate, occur atCanyonlands.Table 1: Colorado Sulfate and Nitrate Impacts on Nearby Class I areasThe emission inventories associated with PSAT and WEP were developed by the WRAP (primarily under contract by the EasternResearch Group) based on on-the-books (OTB) and on-the-way (OTW) emission control assumptions. For purposes of the 110Transport SIP, only federally enforceable controlsmay be considered in determining a State’s impact on a nearby Class I area.Consequently, some of the Colorado OTB and OTW emissions reductions that were included in the 2018 base case inventory are notfederally enforceable and must be added back into the emission projections to ensure the most conservative impact to a nearby out-ofstate Class I area is determined. Table 2 providesa summary of the emission reductions (Submitted toEPA and State-Only) that havebeen added back into the emission inventory for purposes of determining visibility impacts. Since anticipated SO2 emission reductionsat sources such as Drake and Pawnee were not included in the emission inventory for Base 2018b, therewas no need to add themback when rescaling the PSAT results. The same istrue for NOx emission reductions at the CEMEX Lyonscement plant.Page 4Table 2: Summary of Control Program Emission Reductions and Enforceability - from 110 SIPIn light of the fact that the WRAP RMC is now disbanded, there is no ability to perform another PSAT run reflecting those Coloradoemission controls that are not federally enforceable that should be added back into the emission inventory. Consequently, a simplifiedscaling method was developed as a means for ascertaining changes to visibility impacts at a particularClass I area. Figures 2 and 3provide an example demonstration of the visibilitychanges at Canyonlands for sulfate and nitrate thatare estimated based onincreases to Colorado’s emissions due to lack of federal enforceability.Measure PollutantSIP Approved[tons/year]SO2 NOx VOC SO2 NOx VOCCraig & Hayden Controls SO218,000O&G Tank Controls in Front Range by 2007 VOC52,000Mobile Source Fleet Turnover by 2020 NOx & VOC55,000O&G RICE Controls - EAC by 2005 NOx & VOC8,300Drake Controls SO26,200Pawnee Controls SO29,000Cemex Controls NOx1,200Metro VERA SO224,000Comanche Controls SO26,500Additional O&G Tank Controls in FR by 2010 VOC18,000Mobile Source I/M Program & Fuels NOx & VOC4,0004,000O&G Pnuematic Controls - Statewide VOC8,400O&G Tank Controls - Statewide VOC5,600O&G RICE Controls - Statewide by 2010 NOx & VOC5,8001,300Araphaoe & Cameo Shutdown SO2 & NOx5,3003,200Totals: 133,30045,7005,20022,0005,3009,00015,300Combined Totals:Total SO2 - Not Federally Enforceable :30,500tpyTotal NOx - Not Federally Enforceable :4,000tpyTotal VOC - Not Federally Enforceable :4,000tpyNote: It is assumed that recent mobile I/M and fuels program are not federally enforceable and werethus alsoadded back in Base 18.Note: Cemex SNCR NOx reductions not in Base 2018bEI, O&G RICE adopted (Dec 2008) after development of Base2018b (May 2007), thus not in EI, not sure about Mobile NOx reductions, thus added back in Base 18b.Note: O&G Tank Controls, O&G Pnuematic Controls,O&G Statewide RICE & Tanks Controls adopted (Dec 2008) afterdevelp of Base 2018b (May 2007), thus not in EI.Note: Drake,Pawnee, Arapahoe & Cameo SO2 reductions not in Base 2018b emission inventory.Summary of Control Program Emission Reductions forNOx, SO2 and VOCSubmitted to EPA [tons/year] State-Only [tons/year]235,800Page 5Figure 2: Canyonlands 2018 Worst Days – Rescaled 2018 Sulfate Model ProjectionAs indicated in the Figure 2 above, SO2 emissions were increased by 30,500 tons per year (see red box)because the reductions arenot federally enforceable (e.g. either submitted toEPA and not yet acted upon or State-only). The resultant rescaled 2018 sulfatemodel projection is 5.175 Mm-1 (see red arrow), which is about 0.87% higher than the original PSAT model projection. Considering theminimal sulfate impact from Colorado sources (originally 2.30% and increased to 3.17%), it is not surprising that the sulfate extinctionchange is so small.Canyonlands National ParkEmissions Potential AnalysisSulfate BaselineExtinctionSource RegionOriginalOverall PSATImpactRescaledOverall PSATImpactChange inPSAT ImpactSource CategoryPSAT CategoryContributionSub CategorySub CategoryContributionSub CategoryEmissionsEmissions that arenot federallyenforceableRevised SubCategoryEmissionsOriginal SO2Emissions [tpy]Revised SO2Emissions [tpy]Other WRAP States39.08%39.08%0.00%All Sources12,166,29412,166,294Outside Domain*35.47%35.47%0.00%GeosChemUnknownUnknownCEN & EUS3.12%3.12%0.00%All Sources8,430,9308,430,930CAN, MEX & PO20.03%20.03%0.00%All Sources2,835,1432,835,143Colorado2.30%3.17%0.87%All Sources80,272110,772100.00% 100.87%Point85.7%69,21399,713External Combustion Boilers 89.4% 61,85430,50092,354Sulfate ExtinctionIndustrial Processes8.6%5,978-5,978[Mm-1]--Baseline bSO4:5.58030,5002018 URP bSO4:4.240Area 7.1%7,5787,578Model Projection:5.130Stationary Source Fuel Combustion 98.8% 7,490-7,490Rescaled Model Projection:5.175--% Change in Model Projection:0.87%---Mobile 7.1%939939On-Road Mobile 60.5% 568-568Off-Road Mobile 39.5% 371-371---Nat. Fires & Bio. 0.0%2,5422,542Natural Fire 100.0% 2,542-2,542-----All Sources 100.0% Total Increase: 30,50080,272110,772Notes:SO2 [tons/year]24.6%See Emissions Reductions Spreadsheet for SO2 emissions that are not federally enforceable.* Aproximately 35% of Sulfate is fromoutside model domain (mostly globaltransport)Page 6Figure 3: Canyonlands 2018 Worst Days – Rescaled 2018 Nitrate Model ProjectionSimilarly, as indicated in Figure 3 above, NOx emissions were increased by 4,000 tons per year (see red box) because the reductionsare not federally enforceable, (e.g. either submitted to EPA and not yet acted upon or state-only). The resultant rescaled 2018 nitratemodel projection is 3.053 Mm-1 (see red arrow), which is about 0.09% higher than the original PSAT model projection. Considering theminor nitrate impact from Colorado sources (originally 6.88% and increased to 6.97%) and the small increase in NOx emissions, it isnot surprising that the nitrate extinction change is so small.Unfortunately, the organic carbon (OC) PSAT modeling was limited to tracking three categories of OC (primary anthropogenic/biogenic,secondary biogenic, and secondary anthropogenic) but no state or regional attribution was included. Consequently, it is not possible toCanyonlands National ParkEmissions Potential AnalysisNitrate BaselineExtinctionSource RegionOverall PSATImpactRescaledOverall PSATImpactChange inPSAT ImpactSource CategoryPSAT CategoryContributionSub CategorySub CategoryContributionSub CategoryEmissionsEmissions that arenot federallyenforceableRevised SubCategoryEmissionsOriginal NOxEmissions [tpy]Revised NOxEmissions [tpy]Other WRAP States68.13%68.13%0.00%All Sources14,385,99014,385,990Outside Domain*22.50%22.50%0.00%GeosChemUnknownUnknownCEN & EUS0.00%0.00%0.00%All Sources10,187,65010,187,650CAN, MEX & PO2.50%2.50%0.00%All Sources2,689,0382,689,038Colorado6.88%6.97%0.09%All Sources289,669293,669100.00% 100.09%Point27.3%112,240112,240External Combustion Boilers 71.3% 79,982-79,982Nitrate ExtinctionInternal Combustion Engines19.3%21,705-21,705[Mm-1]Industrial Processes9.0%10,106-10,106Baseline bSO4:2.970-2018 URP bSO4:2.430Area45.5%44,73144,731Model Projection:3.050Industrial Processes 61.9% 27,709-27,709Rescaled Model Projection:3.053Stationary Source Fuel Combustion 36.5% 16,321-16,321% Change in Model Projection:0.09%---Mobile18.2%86,05390,053On-Road Mobile 52.6% 45,2494,00049,249Off-Road Mobile 47.4% 40,804-40,804--4,000Nat. Fires & Bio.9.1%46,64646,646Natural Fire 19.9% 9,297-9,297Biogenic 80.1% 37,349-37,349---All Sources 100.0% Total Increase: 4,000289,669293,669Notes:See Emissions Reductions Spreadsheet for NOx emissions that are not federally enforceable.13.1%NOx [tons/year]* Aproximately 23% of Nitrate is fromoutside model domain (mostly globaltransport)determine Colorado OC impacts at Canyonlands or anychanges in visibility associated with changes to VOC emissions. However,important to note that anthropogenic SOA representsa very small portion of total particulate OC at Can4. Therefore, VOC emissions (form secondary organic aerosol) are a very small contributor to total particulate OC.Figure 4: Canyonlands Organic Aerosol PSAT modeling for 2018 Worst DaysIn summary the rescaled PSAT model projectionsand nitrate (0.09%).Converting these rescaled extinction values to adeciview metricdifficult without the original PSAT model input andoutput files since the conversion to deciviews involves a logarithmic funMoreover, andas noted earlier, the PSAT predictions represent impacts in the 2018 base case and not the 2018 reasonablecase. However,it is possible to approximate the change in the reasonablerecalculate the baseline haze index (2000-2004) using daily 20% worse case monitored species2)recalculate 2018 predicted reasonable progress goalhaze index by applying Class I Area specific annual relative response fac(RRFs) provided by WRAP to the daily 20% worst case monitored for each pollutant; 3) assume thatnitrates and sulfates identifiedby WRAP tracer modeling for the 2018 base case is same for the 2018 reasonable progress case;4) rescale sulfate extinctionand nitrate extinction in step 2recalculate the reasonable progress goals that would be expected.determine Colorado OC impacts at Canyonlands or anychanges in visibility associated with changes to VOC emissions. However,important to note that anthropogenic SOA representsa very small portion of total particulate OC at Canyonlands as indicated in Figure4. Therefore, VOC emissions (form secondary organic aerosol) are a very small contributor to total particulate OC.Figure 4: Canyonlands Organic Aerosol PSAT modeling for 2018 Worst Daysdel projectionsfor the 2018 base caseindicate very small increases in extinction for sulfatedeciview metric, as used to establish reasonable progress goals,difficult without the original PSAT model input andoutput files since the conversion to deciviews involves a logarithmic funas noted earlier, the PSAT predictions represent impacts in the 2018 base case and not the 2018 reasonableit is possible to approximate the change in the reasonableprogress goalby using the following procedure2004) using daily 20% worse case monitored speciesextinction from WRAP data;recalculate 2018 predicted reasonable progress goalhaze index by applying Class I Area specific annual relative response fac(RRFs) provided by WRAP to the daily 20% worst case monitored for each pollutant; 3) assume thatColorado’s relative contrby WRAP tracer modeling for the 2018 base case is same for the 2018 reasonable progress case;and nitrate extinction in step 2to account for Colorado emissions that are not federallrecalculate the reasonable progress goals that would be expected.Note that in approximating the change in the reasonable progressPage 7determine Colorado OC impacts at Canyonlands or anychanges in visibility associated with changes to VOC emissions. However,it isyonlands as indicated in Figure4. Therefore, VOC emissions (form secondary organic aerosol) are a very small contributor to total particulate OC.Figure 4: Canyonlands Organic Aerosol PSAT modeling for 2018 Worst Daysindicate very small increases in extinction for sulfate(0.87%), as used to establish reasonable progress goals,is exceptionallydifficult without the original PSAT model input andoutput files since the conversion to deciviews involves a logarithmic function.as noted earlier, the PSAT predictions represent impacts in the 2018 base case and not the 2018 reasonableprogressby using the following procedure: 1)extinction from WRAP data;recalculate 2018 predicted reasonable progress goalhaze index by applying Class I Area specific annual relative response factorsColorado’s relative contribution ofby WRAP tracer modeling for the 2018 base case is same for the 2018 reasonable progress case;to account for Colorado emissions that are not federally enforceable; and 5)Note that in approximating the change in the reasonable progressgoal, all emission reductions that are not federally enforceable, but that were in the prp18b inventory, are accounted for (eemission reductions at the Drake plant).This method of approximating the change in the hazeindex (given in deciviews) sthe 2018 predicted reasonable progress goalat Canyonlandsmeans of predicting the change to the reasonable progress goal, itAdditional Analysis -PSAT Daily and Annual ContributionsThe following additional analysis is provided as additional weightSO2 and 4,000 tpy of NOx emissions because ofThe annual and daily PSAT impacts at Canyonlands are reviewed.As discussed earlier, Colorado’srescaled sulfateprovides the modeled PSAT sulfateconcentrations (US (EUS), Mexico (MEX), Pacific Ocean (PO), and Outside Domain (OD) for the worst days. Colorado sulfate impacts are below 0μg/m3on an annual basis and decrease significantly inFigure 5: Annual PSAT in2002 and 2018Figure 6 provides Colorado’s daily sulfateimpact ondaily sulfate impacts over 0.02μg/m3occur on multiplepoint sources.goal, all emission reductions that are not federally enforceable, but that were in the prp18b inventory, are accounted for (eThis method of approximating the change in the hazeindex (given in deciviews) sat Canyonlandswould only increase from 10.77 dv to 10.80 dv.means of predicting the change to the reasonable progress goal, itfurther supportsa conclusion that the change wouldPSAT Daily and Annual ContributionsThe following additional analysis is provided as additional weight-of-evidence (WOE) that Colorado’s impact from adding 30,500 tpy ofSO2 and 4,000 tpy of NOx emissions because oflack of federal enforceability results in a negligiblevisibility impact at Canyonlands.The annual and daily PSAT impacts at Canyonlands are reviewed.rescaled sulfateimpact on Canyonlands is estimated at 3.17% on theworst days in 2018. Figure 5concentrations (μg/m3) for each western State along with Canada (CAN), CENRAP (CEN), EasternUS (EUS), Mexico (MEX), Pacific Ocean (PO), and Outside Domain (OD) for the worst days. Colorado sulfate impacts are below 0on an annual basis and decrease significantly in2018 because of point source reductions.2002 and 2018for Source Region Sulfate Impactsat Canyonlandsimpact onCanyonlandsin 2002 and 2018 on the worst days. As indicated,2018 Coloradooccur on multipledays throughout the year, particularly in July, andare mostly associated withPage 8goal, all emission reductions that are not federally enforceable, but that were in the prp18b inventory, are accounted for (e.g., SO2This method of approximating the change in the hazeindex (given in deciviews) shows thatwould only increase from 10.77 dv to 10.80 dv.While this is a crudea conclusion that the change wouldbe negligible.evidence (WOE) that Colorado’s impact from adding 30,500 tpy ofvisibility impact at Canyonlands.orst days in 2018. Figure 5) for each western State along with Canada (CAN), CENRAP (CEN), EasternUS (EUS), Mexico (MEX), Pacific Ocean (PO), and Outside Domain (OD) for the worst days. Colorado sulfate impacts are below 0.03at Canyonlandson the Worst Daysin 2002 and 2018 on the worst days. As indicated,2018 Coloradodays throughout the year, particularly in July, andare mostly associated withFigure 6: Daily PSAT in2002 and 2018Table 3 provides thedaily 2018 sulfate contributions from Colorado. Onseveral days Colorado contributes in excess ofμg/m3. Point sourcesare the largest contributor to sulfat2002 and 2018for Colorado Nitrate Impacts at Canyonlandson the Worst Daysdaily 2018 sulfate contributions from Colorado. Onseveral days Colorado contributes in excess ofare the largest contributor to sulfate on most days.Page 9on the Worst Daysdaily 2018 sulfate contributions from Colorado. Onseveral days Colorado contributes in excess ofover 0.02Page 10Table 3: Daily PSAT in 2018 for Colorado Sulfate Impacts at Canyonlands on the Worst DaysClass IAreaPollutantDateSourceRegionModelScenarioNat.Fires &Bio.Anthro.FiresMobileAreaPointTotalPointSource % otTotal[ug/m3][ug/m3][ug/m3][ug/m3][ug/m3][ug/m3]CANY1 PS4 1/8/2018CO base18b36k 0 0 0 0.001 0.006 0.007 85.71%CANY1 PS4 4/17/2018CO base18b36k 0 0 0 0 0 0 0.00%CANY1 PS4 5/8/2018CO base18b36k 0 0 0 0 0 0 0.00%CANY1 PS4 5/20/2018CO base18b36k 0.001 0 0 0 0.001 0.002 50.00%CANY1 PS4 6/1/2018CO base18b36k 0 0 0 0 0.001 0.001 100.00%CANY1 PS4 6/22/2018CO base18b36k 0 0 0 0 0 0 0.00%CANY1 PS4 6/28/2018CO base18b36k 0 0 0 0.001 0.002 0.003 66.67%CANY1 PS4 7/1/2018CO base18b36k 0 0 0 0 0 0 0.00%CANY1 PS4 7/4/2018CO base18b36k 0 0 0.001 0.002 0.012 0.015 80.00%CANY1PS47/7/2018CObase18b36k000.0010.0040.030.03585.71%CANY1PS47/10/2018CObase18b36k0.00100.0040.0110.0970.11385.84%CANY1PS47/13/2018CObase18b36k0.00300.0020.0040.0350.04479.55%CANY1PS47/16/2018CObase18b36k0.00400.0010.0030.030.03878.95%CANY1 PS4 7/22/2018CO base18b36k 0 0 0.001 0.001 0.007 0.009 77.78%CANY1 PS4 7/28/2018CO base18b36k 0 0 0 0 0.001 0.001 100.00%CANY1 PS4 8/9/2018CO base18b36k 0 0 0 0 0.001 0.001 100.00%CANY1 PS4 8/12/2018CO base18b36k 0 0 0 0 0 0 0.00%CANY1 PS4 8/18/2018CO base18b36k 0 0 0 0 0 0 0.00%CANY1 PS4 8/21/2018CO base18b36k 0 0 0 0 0 0 0.00%CANY1 PS4 9/26/2018CO base18b36k 0 0 0 0 0.002 0.002 100.00%CANY1 PS4 11/1/2018CO base18b36k 0 0.001 0.001 0.001 0.015 0.018 83.33%CANY1PS412/7/2018CObase18b36k000.0010.0020.020.02386.96%Colorado’s rescaled nitrate impact on Canyonlands is estimated at 6.97% on the worst days in 2018. Figure 7 provides the modeledPSAT nitrate concentrations (μg/m3) for each western State along with Canada (CAN), CENRAP (CEN), Eastern US (EUS), Mexico(MEX), Pacific Ocean (PO), and Outside Domain (OD)for the worst days. Colorado nitrate impacts are just above 0.01μg/m3on anannual basis and decrease slightly in 2018 becauseof mobile source reductions.Figure 7: Annual PSAT in2002 and 2018Figure 8 provides Colorado’s daily nitrateimpact ondaily nitrate impacts over 0.02μg/m3occurin the summer and winter and primarily as the result of point, area, and mobile emissions2002 and 2018for Source Region Nitrate Impacts at Canyonlandsimpact onCanyonlandsin 2002 and 2018 on the worst days. As indicated,2018 Coloradoin the summer and winter and primarily as the result of point, area, and mobile emissionsPage 11on the Worst Daysin 2002 and 2018 on the worst days. As indicated,2018 Coloradoin the summer and winter and primarily as the result of point, area, and mobile emissions.Figure 8: Daily PSAT in2002 and 2018Table 4 provides thedaily 2018 nitrate contributions from Colorado. There are multiple days identified on which ColoradoContributesgreater than 0.02μg/m3.2002 and 2018for Colorado Nitrate Impacts at Canyonlandson the Worst Daysdaily 2018 nitrate contributions from Colorado. There are multiple days identified on which ColoradoContributesPage 12daily 2018 nitrate contributions from Colorado. There are multiple days identified on which ColoradoContributesPage 13Table 4: Daily PSAT in 2018 for Colorado Nitrate Impacts at Canyonlands on the Worst DaysClass IAreaPollutantDateSourceRegionModelScenarioNat.Fires &Bio.Anthro.FiresMobileAreaPointTotalPointSource %ot Total[ug/m3][ug/m3][ug/m3][ug/m3][ug/m3][ug/m3]CANY1PN31/8/2018CObase18b36k0.00400.0130.0050.0140.03638.89%CANY1 PN3 4/17/2018 CO base18b36k 0 0 0 0 0 0 0.00%CANY1 PN3 5/8/2018 CO base18b36k 0 0 0 0 0 0 0.00%CANY1 PN3 5/20/2018 CO base18b36k 0 0 0 0 0 0 0.00%CANY1 PN3 6/1/2018 CO base18b36k 0 0 0 0 0 0 0.00%CANY1 PN3 6/22/2018 CO base18b36k 0 0 0 0 0 0 0.00%CANY1 PN3 6/28/2018 CO base18b36k 0.001 0 0.001 0.006 0.001 0.009 11.11%CANY1 PN3 7/1/2018 CO base18b36k 0 0 0 0 0 0 0.00%CANY1 PN3 7/4/2018 CO base18b36k 0.001 0 0 0.003 0.001 0.005 20.00%CANY1PN37/7/2018CObase18b36k0.00200.0030.0130.0050.02321.74%CANY1 PN3 7/10/2018 CO base18b36k 0 0 0.001 0 0.0010.002 50.00%CANY1 PN3 7/13/2018 CO base18b36k 0 0 0 0 0 0 0.00%CANY1 PN3 7/16/2018 CO base18b36k 0 0 0 0 0 0 0.00%CANY1 PN3 7/22/2018 CO base18b36k 0 0 0 0 0 0 0.00%CANY1 PN3 7/28/2018 CO base18b36k 0 0 0 0 0 0 0.00%CANY1 PN3 8/9/2018 CO base18b36k 0 0 0 0 0 0 0.00%CANY1 PN3 8/12/2018 CO base18b36k 0 0 0 0 0 0 0.00%CANY1 PN3 8/18/2018 CO base18b36k 0 0 0 0 0 0 0.00%CANY1 PN3 8/21/2018 CO base18b36k 0 0 0 0 0 0 0.00%CANY1 PN3 9/26/2018 CO base18b36k 0.002 0 0.002 0.003 0.001 0.008 12.50%CANY1PN311/1/2018CObase18b36k0.0060.0010.0130.0310.0260.07733.77%CANY1PN312/7/2018CObase18b36k0.00400.0130.0390.0190.07525.33%WEP Evaluation of Colorado Impacts on nearby ClassI areas:The following WEP analysis is provided as additional weight-of-evidence (WOE) that Colorado’s sulfateand nitrate impacts onCanyonlands. As indicated in Figure 9, the dominant grid cells that contribute to air parcels arriving in Canyonlands are in Utah andArizona. Figure 10 below, provides the SOx WEP forCanyonlands. As shown, none of the 36-km grid cells in Colorado contributemore than 10% on a normalized scale. Similarly, Figure 11 below provides the NOx WEP for Canyonlands.Again, none of the 36-kmgrid cells in Colorado contribute more than 10% ona normalized scale.Page 14The WEP analysis results further support a conclusion that Colorado does not interfere with the ability of nearby States to meet theirreasonable progress goals.Figure 9: Canyonlands 5-Year Meteorology (2000-2004) Back-Trajectories for the Worst DaysPage 15Figure 10: Canyonlands SOx Weighted Emissions Potential for the 2018 Worst DaysPage 16Figure 11: Canyonlands NOx Weighted Emissions Potential for the 2018 Worst DaysPage 17Review of Current and Future Year InventoriesIn Colorado, Regulation Number 3 (Stationary SourcePermitting) requires any non-exempt stationary source with over 1 ton/year(uncontrolled actual emissions in a non-attainmentarea) or 2 ton/year (uncontrolled actual emissionsin an attainment or maintenancearea) of criteria pollutant emissions to file an Air Pollutant Emissions Notice (APEN) with the Division. Thus, Colorado’s point sourceemission threshold is very low relative to most western states and any stationary sources below the APEN threshold are categorized asarea sources.The PSAT modeling incorporated a present and futureemission inventory (Plan 2002c and Base 2018b) that include 12 sourcecategories (see Table 5). These 12 categories weremapped into five categories in the PSAT model: point, area, mobile, naturalfires/biogenic, and anthropogenic fires. The emission inventories show a net decrease of 32,799.2 tpyof SO2 and 114,656.6 tpy ofNOx between 2002 (Plan 2002c) and 2018 (Base 2018b)before the implementation of any anticipated BARTor reasonable progresscontrols.Table 5: Colorado Emission Inventories used in PSAT modeling (Plan 2002c and Base 2018b)The Base 2018b emission inventory (EI) contains about 3,350 tpy of surplus SO2 in the Colorado point source emissions associatedwith two future power plants that have been removedfrom the latest PRP 2018b emission inventory. Thus, adding 30,500 tpy of SO2(see the above PSAT analysis - Figure 2) produces aslightly conservative estimate of a 0.87% increasein sulfate extinction.Region Scenario Year Point [tpy]AnthroFire [tpy]NaturalFire[tpy]Biogenic[tpy]Area[tpy]WRAPArea O&G[tpy]Off-Shore[tpy]On-RoadMobile[tpy]Off-RoadMobile[tpy]Road Dust[tpy]FugitiveDust[tpy]WB Dust[tpy]Total [tpy]CO Plan02c 2002 97016.4 107.6 3334.9-6504.4 259.7-4389.2 3014.9 4.1 4.9-114636.1CO Base18b 2018 69262.5 91.4 3334.9-7676.1 8.5-676.6 780.7 0.0 6.3-81836.9Delta (27753.9) (16.3) 0.0 - 1171.7 (251.2) - (3712.6) (2234.3) (4.1) 1.4 -(32799.2)Reduction Percentage: -28.6%-15.1%0.0%- 18.0%-96.7%- -84.6%-74.1%-100.0%29.1%-Source C ategory % of Total: 84.6%0.1%4.1%- 9.4%0.0%- 0.8%1.0%0.0%0.0%-Region Scenario Year Point [tpy]AnthroFire [tpy]NaturalFire[tpy]Biogenic[tpy]Area[tpy]WRAPArea O&G[tpy]Off-Shore[tpy]On-RoadMobile[tpy]Off-RoadMobile[tpy]Road Dust[tpy]FugitiveDust[tpy]WB Dust[tpy]Total [tpy]CO Plan02c 2002 117868.9 519.9 9377.1 37348.8 11645.1 23350.9-141883.5 62447.2 0.9 13.3-404455.5CO Base18b 2018 112241.2 408.5 9377.1 37348.8 16360.3 27992.9-45249.1 40803.9 0.0 17.2-289798.9Delta (5627.7) (111.4) 0.0 0.0 4715.2 4642.0 - (96634.4) (21643.3) (0.9) 3.9 -(114656.6)Reduction Percentage: -4.8%-21.4%0.0%0.0%40.5%19.9%- -68.1%-34.7%-100.0%29.2%-Source C ategory % of Total: 38.7%0.1%3.2%12.9%5.6%9.7%- 15.6%14.1%0.0%0.0%-Sulfur Dioxide (gas and particulates)Nitrogen oxides (gas and particulates)Page 18Similarly, the Base 2018b emission inventory (EI) contains about 3,350 tpy of surplus NOx increases inthe Colorado point sourceemissions associated with the two future power plants that have been removed from the latest PRP 2018bemission inventory. TheBase 2018b EI also includes 4,000 tpy of Colorado mobile source NOx reductions that may not be federally enforceable (impossible todetermine from the EI) and therefore these NOx reductions are added back into the Base 2018b EI. Thenet NOx difference betweenthe apparent surplus and restored increase is 650 tpy (+4,000 - 3,350 = +650). Thus, adding 4,000 tpyof NOx (see the above NitratePSAT analysis - Figure 3) produces a very conservative estimate of a 0.09% increase in nitrate extinction.Colorado point source baseline emissions were estimated by using reported APEN emission data for 2002that was grown usingEconomic Growth Analysis System (EGAS) model to forecast future emissions in 2018. Since electric generating units (EGUs)represent a large portion of SO2 and NOx emissions,the WRAP used projected 2018 power demand from thefederal EnergyInformation Administration (EIA) to estimate the number of future power plants across the west. In Colorado, the Base 2018b emissioninventory included two additional 500 MW power plants and the newly constructed 750 MW Comanche Unit 3(see Tables 6 and 7below – highlighted in orange). The SO2 and NOx emissions for the other power plants were based on the 2002 base year that wasgrown to 2018 based on utilization factors along with consideration of any future emission controls.The SO2 and NOx emission reductions associated withBART were included in the latest PRP 2018b emission inventory which isindicated in Tables 4 and 5, respectively (new Comanche Unit 3 is highlighted in orange). The shutdown of Arapahoe and Cameo areanticipated by 2018, so no emissions from these twosources are included in the total. The two futurepower plants were removed fromthe PRP 2018b emission inventory because of decreased projections of annual electricity demand, as well demand offset by therenewable energy portfolio standards in Colorado.Together these have diminished the need for an additional 1,000 MW of generatingcapacity in 2018.Based on a review of the current and future emission inventory information, it can be concluded that nearby States will not need to relyon the Colorado measures that are not yet federallyenforceable in order to meet their reasonable progress goals.Page 19Table 6: Significant Coal-Fired Boilers included in the Plan 2002c/Base 2018b/PRP 2018b Point SourceEmission Sulfur DioxideInventoriesPage 20Table 7: Significant Coal-Fired Boilers included in the Plan 2002c/Base 2018b/PRP 2018b Point SourceNitrogen Oxide EmissionInventories