1

December 13, 2012

Summary of EPA’s Revised Additional Visibility Improvement Modeling

for Wyoming’s 309(g) SIP

In response to comments on its proposal, EPA has performed new CALPUFF visibility 

modeling using revised baseline emissions rates. All Region 8 modeling files are available upon 

request. Contact Laurel Dygowski at dygowski.laurel@epa.gov.

As explained in our proposed notice, EPA had previously performed additional modeling 

of NOx control scenarios for both BART and reasonable progress sources. This modeling was 

performed to ascertain visibility improvements from individual NOx controls that the State and 

BART sources had not individually evaluated. For baseline emissions, the BART Guidelines 

recommend that states use the maximum 24-hour average actual emission rate for the 

meteorological period being modeled. The visibility modeling performed by PacifiCorp, and 

subsequently submitted by the State, deviates from this guidance by using the permit limit

emission rates and maximum rated heat input to derive the modeled emission rates instead of the

actual maximum 24-hour average. The visibility modeling performed by Basin Electric, and 

subsequently submitted by the State, also deviates from this guidance by using a baseline hourly 

emission rates derived from actual annual average heat input (MMBtu) and actual annual 

average emission rates (lb/MMBtu) from 2001-2003 continuous emissions monitoring (CEM) 

data. For consistency, EPA‟s previously completed additional modeling used the State‟s 

baseline emission rates for the PacifiCorp sites and Basin Electric‟s Laramie River Station. All 

other aspects of EPA‟s additional visibility modeling followed the recommendations made in the 

State of Wyoming Department of Environmental Quality (WY DEQ) BART Air Modeling 
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Protocol.

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In response to comments that EPA should have followed the WY DEQ BART Air 

Modeling Protocol for its additional modeling, EPA has now performed new modeling using the 

maximum 24-hour average actual emission rates. The results of this new modeling are 

summarized in this document.

 Tables 3 through 11 show the CALPUFF inputs used for each unit modeled. EPA‟s 

modeling modified the State of Wyoming‟s inputs in order to isolate the impact of different NOx 

control scenarios. As seen in the tables, the NOx emission rates were varied across the different 

scenarios with the other input parameters held constant. For the PacifiCorp and Basin Electric 

BART sources, the inputs were derived from the State of Wyoming‟s BART Application 

Analyses that can be downloaded from the following website: 

http://deq.state.wy.us/aqd/309(g)%20Attachment%20A_January%202011%20Submittal.asp

EPA‟s modeling utilized the emission and stack parameter CALPUFF inputs from “Post-Control 

Scenario A” in the State‟s? reports for its Scenarios 1-3 with the only difference between 

scenarios being the emission rate for NOx and, in the SCR scenarios, total sulfate rates were 

increased to account for the additional production of ??? that results from SCR controls. EPA‟s 

“New Baseline” is essentially the State‟s “Post-Control Scenario A” but with the NOx emission 

rate from their “Baseline” scenario. Table 1 summarizes the control scenarios from EPA‟s 

additional modeling for BART sources.

Table 1- Description of EPA control scenarios for Wyoming’s BART sources

EPA Scenario Description

New Baseline Post-Control Scenario A from State„s BART Application Analysis with NOx 

emission rate from state‟s “Baseline” scenario

Scenario 1 Post-Control Scenario A from State‟s BART Application Analysis with NOx 

 

1

State of Wyoming Department of Environmental Quality Air Quality Division BART Air Modeling Protocol – Individual 

Source Visibility Impairment Analysis, March 2006, 

http://deq.state.wy.us/aqd/308%20SIP/BART%20AIR%20MODELING%20PROTOCOL%20(March,%202006)_Chap.%206.pdf.
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emission rate that reflects the visibility improvement from LNB/OFA 

controls.

Scenario 2 Post-Control Scenario A from State‟s BART Application Analysis with NOx 

emission rate that reflects the visibility improvement from SNCR controls

Scenario 3 Post-Control Scenario A from State‟s BART Application Analysis with NOx 

emission rate that reflects the visibility improvement from SCR controls

EPA also performed additional modeling for Dave Johnston‟s Units 1 and 2 (see Table 12 

and Table 13). These are considered reasonable progress sources and were not part of the State‟s 

BART Application Analyses. For consistency, EPA followed a similar approach for modeling 

these sources as used for the BART sources. Permit limit emission rates with heat input were 

used to derive emission inputs in the “New Baseline” scenario. Similar to the BART sources, the 

only differences in the control scenarios are the emission rates for NOx and, in the SCR scenario 

(Scenario 3), total sulfate rates were increased to account for the additional production that

results from SCR controls. Stack parameter data for these sources was obtained from the 

Western Region Air Partnership‟s (WRAP) 2002 SMOKE input files. Table 2 summarizes the 

control scenarios for EPA‟s reasonable progress source modeling.

Table 14 through Table 17 present the results of the additional visibility modeling for all 

units at each subject facility. Using the updated CALPUFF output, the 98th percentile or 8th

maximum 24-hour visibility impact (deciview [Δdv]) was determined at all Class I areas within 

300 kilometers of the subject facility for each year between 2001 and 2003. These tables also 

present the visibility improvements for EPA Scenario 1, Scenario 2, and Scenario 3, which was 

determined by the difference between the New Baseline and EPA Scenario. 

Table 2 – Description of EPA control scenarios for Reasonable Progress sources (Dave 

Johnston Units 1 and 2)

EPA Scenario Description

New Baseline Inputs obtained from facility‟s Title V Operating Permit limits

Scenario 1 Same inputs as New Baseline with a NOx emission rate that reflect visibility 
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improvements from LNB/OFA controls

Scenario 2 Same inputs as New Baseline with a NOx emission rate that reflect visibility 

improvements from SNCR controls

Scenario 3 Same inputs as New Baseline with a NOx emission rate that reflect visibility 

improvements from SCR controls

Table 3 – Modeling Assumptions for PacifiCorp - Dave Johnston Unit 3

CALPUFF Inputs New Baseline Scenario 1 Scenario 2 Scenario 3

SO2 (lb/hr) 420 420 420 420

Total Sulfate (SO4)(lb/hr) 2.5 2.5 2.5 5.1

Nox (lb/hr) 1671.0 706.3 529.7 163.3

HNO3 0 0 0 0

NO3 0 0 0 0

PM10-2.5 

(coarse PM)(lb/hr) 23.9 23.9 23.9 23.9

PM2.5 (lb/hr) 18.1 18.1 18.1 18.1

Stack Height (meters) 152.4 152.4 152.4 152.4

Base Elevation (meters) 1509 1509 1509 1509

Stack Diameter (meters) 4.57 4.57 4.57 4.57

Exit Velocity 

(meters/second) 25.5 25.5 25.5 25.5

Exit Temperature (Kelvin) 348 348 348 348

Table 4 – Modeling Assumptions for PacifiCorp - Dave Johnston Unit 4

CALPUFF Inputs New Baseline Scenario 1 Scenario 2 Scenario 3

SO2 (lb/hr) 615 615 615 615

Total Sulfate (SO4)(lb/hr) 3.7 3.7 3.7 7.4

Nox (lb/hr) 1983.0 765.1 612.1 270.8

HNO3 0 0 0 0

NO3 0 0 0 0

PM10-2.5 

(coarse PM)(lb/hr) 35.1 35.1 35.1 35.1

PM2.5 (lb/hr) 26.4 26.4 26.4 26.4

Stack Height (meters) 152 152 152 152

Base Elevation (meters) 1509 1509 1509 1509

Stack Diameter (meters) 5.79 5.79 5.79 5.79

Exit Velocity 

(meters/second) 25.7 25.7 25.7 25.7

Exit Temperature (Kelvin) 350 350 350 350
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Table 5 – Modeling Assumptions for PacifiCorp - Naughton Unit 1

CALPUFF Inputs New Baseline Scenario 1 Scenario 2 Scenario 3

SO2 (lb/hr) 278 278 278 278

Total Sulfate (SO4)(lb/hr) 16.7 16.7 16.7 33.3

Nox (lb/hr) 1322.0 540.7 405.5 128.2

HNO3 0 0 0 0

NO3 0 0 0 0

PM10-2.5 

(coarse PM)(lb/hr) 33.4 33.4 33.4 33.4

PM2.5 (lb/hr) 44.3 44.3 44.3 44.3

Stack Height (meters) 145 145 145 145

Base Elevation (meters) 2115 2115 2115 2115

Stack Diameter (meters) 4.88 4.88 4.88 4.88

Exit Velocity 

(meters/second) 18.1 18.1 18.1 18.1

Exit Temperature (Kelvin) 323 323 323 323

Table 6 – Modeling Assumptions for PacifiCorp - Naughton Unit 2

CALPUFF Inputs New Baseline Scenario 1 Scenario 2 Scenario 3

SO2 (lb/hr) 360 360 360 360

Total Sulfate (SO4)(lb/hr) 21.6 21.6 21.6 43.2

Nox (lb/hr) 1636.0 660.7 495.5 156.7

HNO3 0 0 0 0

NO3 0 0 0 0

PM10-2.5 

(coarse PM)(lb/hr) 55.7 55.7 55.7 55.7

PM2.5 (lb/hr) 73.9 73.9 73.9 73.9

Stack Height (meters) 145 145 145 145

Base Elevation (meters) 2115 2115 2115 2115

Stack Diameter (meters) 5.49 5.49 5.49 5.49

Exit Velocity 

(meters/second) 18.5 18.5 18.5 18.5

Exit Temperature (Kelvin) 323 323 323 323

Table 7 – Modeling Assumptions for PacifiCorp - Naughton Unit 3

CALPUFF Inputs New Baseline Scenario 1 Scenario 2 Scenario 3

SO2 (lb/hr) 814 814 814 814

Total Sulfate (SO4)(lb/hr) 33.3 33.3 33.3 66.6

Nox (lb/hr) 2368.0 2137.4 1496.2 323.9
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HNO3 0 0 0 0

NO3 0 0 0 0

PM10-2.5 

(coarse PM)(lb/hr) 23.9 23.9 23.9 23.9

PM2.5 (lb/hr) 31.6 31.6 31.6 31.6

Stack Height (meters) 145 145 145 145

Base Elevation (meters) 2113 2113 2113 2113

Stack Diameter (meters) 8.08 8.08 8.08 8.08

Exit Velocity 

(meters/second) 20.2 20.2 20.2 20.2

Exit Temperature (Kelvin) 322 322 322 322

Table 8 – Modeling Assumptions for PacifiCorp – Wyodak

CALPUFF Inputs New Baseline Scenario 1 Scenario 2 Scenario 3

SO2 (lb/hr) 759 759 759 759

Total Sulfate (SO4)(lb/hr) 5.5 5.5 5.5 11.6

Nox (lb/hr) 1397.0 1022.0 817.6 266.4

HNO3 0 0 0 0

NO3 0 0 0 0

PM10-2.5 

(coarse PM)(lb/hr) 70.5 70.5 70.5 70.5

PM2.5 (lb/hr) 40.2 40.2 40.2 40.2

Stack Height (meters) 122 122 122 122

Base Elevation (meters) 1347 1347 1347 1347

Stack Diameter (meters) 6.1 6.1 6.1 6.1

Exit Velocity 

(meters/second) 23.5 23.5 23.5 23.5

Exit Temperature (Kelvin) 350 350 350 350

Table 9 – Modeling Assumptions for Basin Electric – Laramie River Station Unit 1

CALPUFF Inputs New Baseline Scenario 1 Scenario 2 Scenario 3

SO2 (tpy) 3745 3745 3745 3745

Total Sulfate (SO4)(tpy) 3.06 3.18 3.18 3.18

Nox (tpy) 9557.16 7099.1 5679.1 1848.8

HNO3 0 0 0 0

NO3 0 0 0 0

PM10-2.5 

(coarse PM)(tpy) 0 0 0 0

PM2.5 (tpy) 702 702 702 702

Stack Height (meters) 184.404 184.404 184.404 184.404
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Base Elevation (meters) 1348 1348 1348 1348

Stack Diameter (meters) 8.6868 8.6868 8.6868 8.6868

Exit Velocity 

(meters/second) 21.336 21.336 21.336 21.336

Exit Temperature 

(Kelvin) 338.7056 338.7056 338.7056 338.7056

Table 10 – Modeling Assumptions for Basin Electric – Laramie River Station Unit 2

CALPUFF Inputs New Baseline

Scenario 

1 Scenario 2 Scenario 3

SO2 (tpy) 3725 3725 3725 3725

Total Sulfate (SO4)(tpy) 2.8 3.25 3.25 3.25

Nox (tpy) 8786.3 6240.6 4992.8 1625.0

HNO3 0 0 0 0

NO3 0 0 0 0

PM10-2.5 

(coarse PM)(tpy) 0 0 0 0

PM2.5 (tpy) 698 698 698 698

Stack Height (meters) 184.404 184.404 184.404 184.404

Base Elevation (meters) 1348 1348 1348 1348

Stack Diameter 

(meters) 8.6868 8.6868 8.6868 8.6868

Exit Velocity 

(meters/second) 21.03 21.03 21.03 21.03

Exit Temperature 

(Kelvin) 338.7056 338.7056 338.7056 338.7056

Table 11 – Modeling Assumptions for Basin Electric – Laramie River Station Unit 3

CALPUFF Inputs New Baseline Scenario 1 Scenario 2 Scenario 3

SO2 (tpy) 4060 4060 4060 4060

Total Sulfate (SO4)(tpy) 0.22 0.22 0.22 0.22

Nox (tpy) 8834.5 6354.9 5083.9 1654.8

HNO3 0 0 0 0

NO3 0 0 0 0

PM10-2.5 (coarse 

PM)(tpy) 0 0 0 0

PM2.5 (tpy) 716 716 716 716

Stack Height (meters) 184.404 184.404 184.404 184.404

Base Elevation (meters) 1348 1348 1348 1348

Stack Diameter (meters) 8.6868 8.6868 8.6868 8.6868

Exit Velocity 22.25 22.25 22.25 22.25
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(meters/second)

Exit Temperature 

(Kelvin) 352.0 352.0 352.0 352.0
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Reasonable Progress Sources 

Table 12 – Modeling Assumptions for PacifiCorp - Dave Johnston Unit 1

CALPUFF Inputs New Baseline Scenario 1 Scenario 2 Scenario 3

SO2 (lb/hr) 1620 1620 1620 0

Total Sulfate (SO4)(lb/hr) 1 1 1 2

Nox (lb/hr) 679.6 298.8 224.1 74.7

HNO3 0 0 0 0

NO3 0 0 0 0

PM10-2.5 

(coarse PM)(lb/hr) 149.726 149.726 149.726 149.726

PM2.5 (lb/hr) 198.474 198.474 198.474 198.474

Stack Height (meters) 152.4 152.4 152.4 152.4

Base Elevation (meters) 1509 1509 1509 1509

Stack Diameter (meters) 3.35 3.35 3.35 3.35

Exit Velocity 

(meters/second) 28.35 28.35 28.35 28.35

Exit Temperature (Kelvin) 418.15 418.15 418.15 418.15

Table 13 – Modeling Assumptions for PacifiCorp - Dave Johnston Unit 2

CALPUFF Inputs New Baseline Scenario 1 Scenario 2 Scenario 3

SO2 (lb/hr) 1620 1620 1620 1620

Total Sulfate (SO4)(lb/hr) 1 1 1 2

Nox (lb/hr) 653.7 296.7 222.5 74.2

HNO3

NO3

PM10-2.5 

(coarse PM)(lb/hr) 149.726 149.726 149.726 149.726

PM2.5 (lb/hr) 198.474 198.474 198.474 198.474

Stack Height (meters) 152.4 152.4 152.4 152.4

Base Elevation (meters) 1509 1509 1509 1509

Stack Diameter (meters) 3.35 3.35 3.35 3.35

Exit Velocity 

(meters/second) 28.69 28.69 28.69 28.69

Exit Temperature (Kelvin) 425.93 425.93 425.93 425.93
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Table 14 – Model Results for PacifiCorp – Dave Johnston Units

Unit Class I Area

by Year

New Baseline Scenario 1 Scenario 2 Scenario 3

98th Percentile

Visibility Impact

(∆dv)

98th Percentile

Visibility Impact 

(∆dv)

Visibility Improvement 

(∆dv)

98th Percentile

Visibility Impact 

(∆dv)

Visibility Improvement 

(∆dv)

98th Percentile

Visibility Impact 

(∆dv)

Visibility Improvement 

(∆dv)

Unit 1

Badlands 2001 0.824 0.659 0.165 0.631 0.193 0.578 0.246

Badlands 2002 0.585 0.490 0.095 0.462 0.123 0.419 0.166

Badlands 2003 0.773 0.659 0.114 0.618 0.155 0.539 0.234

Wind Cave 2001 0.921 0.717 0.204 0.683 0.238 0.622 0.299

Wind Cave 2002 0.879 0.769 0.110 0.741 0.138 0.686 0.193

Wind Cave 2003 1.226 0.918 0.308 0.874 0.352 0.787 0.439

Unit 2

Badlands 2001 0.802 0.658 0.144 0.631 0.171 0.577 0.225

Badlands 2002 0.590 0.487 0.103 0.460 0.130 0.422 0.168

Badlands 2003 0.774 0.659 0.115 0.617 0.157 0.538 0.236

Wind Cave 2001 0.904 0.701 0.203 0.676 0.228 0.630 0.274

Wind Cave 2002 0.875 0.763 0.112 0.736 0.139 0.683 0.192

Wind Cave 2003 1.206 0.918 0.288 0.873 0.333 0.788 0.418

Unit 3

Badlands 2001 0.800 0.417 0.383 0.350 0.450 0.211 0.589

Badlands 2002 0.641 0.310 0.331 0.250 0.391 0.152 0.489

Badlands 2003 0.882 0.440 0.442 0.359 0.523 0.208 0.674

Wind Cave 2001 1.03 0.529 0.500 0.435 0.594 0.238 0.791

Wind Cave 2002 0.84 0.448 0.395 0.370 0.473 0.230 0.613

Wind Cave 2003 1.32 0.683 0.639 0.564 0.758 0.318 1.004

Mt Zirkel 2001 0.216 0.115 0.101 0.093 0.123 0.061 0.155

Mt Zirkel 2002 0.353 0.177 0.176 0.148 0.205 0.096 0.257

Mt Zirkel 2003 0.439 0.228 0.211 0.190 0.249 0.105 0.334

Rawah 2001 0.264 0.147 0.117 0.122 0.142 0.07 0.191

Rawah 2002 0.486 0.262 0.224 0.222 0.264 0.14 0.349

Rawah 2003 0.484 0.241 0.243 0.197 0.287 0.11 0.375

RMNP 2001 0.311 0.166 0.145 0.139 0.172 0.09 0.224

RMNP 2002 0.475 0.230 0.245 0.189 0.286 0.09 0.381

RMNP 2003 0.688 0.346 0.342 0.281 0.407 0.15 0.539

Unit 4 Badlands 2001 0.995 0.456 0.539 0.456 0.539 0.320 0.675
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Badlands 2002 0.762 0.365 0.397 0.332 0.430 0.222 0.540

Badlands 2003 1.049 0.556 0.493 0.479 0.570 0.322 0.727

Mt Zirkel 2001 0.242 0.124 0.118 0.123 0.119 0.122 0.120

Mt Zirkel 2002 0.424 0.216 0.208 0.189 0.235 0.165 0.259

Mt Zirkel 2003 0.557 0.279 0.278 0.238 0.319 0.192 0.365

Rawah 2001 0.332 0.163 0.169 0.139 0.193 0.100 0.232

Rawah 2002 0.586 0.316 0.270 0.282 0.304 0.208 0.378

Rawah 2003 0.557 0.270 0.287 0.235 0.322 0.169 0.388

RMNP 2001 0.373 0.186 0.187 0.166 0.207 0.122 0.251

RMNP 2002 0.515 0.264 0.251 0.236 0.279 0.149 0.366

RMNP 2003 0.869 0.421 0.448 0.364 0.505 0.239 0.630

Wind Cave 2001 1.164 0.469 0.695 0.468 0.696 0.349 0.815

Wind Cave 2002 1.079 0.533 0.546 0.465 0.614 0.342 0.737

Wind Cave 2003 1.691 0.853 0.838 0.745 0.946 0.478 1.213

Table 15 – Model Results for PacifiCorp – Naughton Units

Unit Class I Area

by Year

New Baseline Scenario 1 Scenario 2 Scenario 3

98th Percentile

Visibility Impact 

(∆dv)

98th Percentile

Visibility Impact 

(∆dv)

Visibility Improvement 

(∆dv)

98th Percentile

Visibility Impact 

(∆dv)

Visibility Improvement 

(∆dv)

98th Percentile

Visibility Impact 

(∆dv)

Visibility Improvement 

(∆dv)

Unit 1

Bridger 2001 1.634 0.799 0.835 0.649 0.985 0.404 1.230

Bridger 2002 1.350 0.675 0.675 0.557 0.793 0.368 0.982

Bridger 2003 1.490 0.756 0.734 0.624 0.866 0.411 1.079

Fitzpatrick 2001 0.732 0.349 0.383 0.283 0.449 0.174 0.558

Fitzpatrick 2002 0.481 0.239 0.242 0.198 0.283 0.131 0.350

Fitzpatrick 2003 0.609 0.304 0.305 0.248 0.361 0.155 0.454

N. Absaroka 2001 0.266 0.129 0.137 0.109 0.157 0.073 0.193

N. Absaroka 2002 0.279 0.141 0.138 0.120 0.159 0.083 0.196

N. Absaroka 2003 0.158 0.079 0.079 0.068 0.090 0.048 0.110

Washakie 2001 0.327 0.166 0.161 0.138 0.189 0.090 0.237

Washakie 2002 0.402 0.205 0.197 0.172 0.230 0.112 0.290

Washakie 2003 0.291 0.145 0.146 0.119 0.172 0.083 0.208

Teton 2001 0.408 0.208 0.200 0.168 0.240 0.113 0.295
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Teton 2002 0.477 0.229 0.248 0.186 0.291 0.121 0.356

Teton 2003 0.331 0.160 0.171 0.132 0.199 0.088 0.243

Grand Teton 2001 0.480 0.230 0.250 0.188 0.292 0.124 0.356

Grand Teton 2002 0.665 0.332 0.333 0.274 0.391 0.177 0.488

Grand Teton 2003 0.331 0.161 0.170 0.131 0.200 0.098 0.233

Yellowstone 2001 0.392 0.198 0.194 0.165 0.227 0.108 0.284

Yellowstone 2002 0.544 0.267 0.277 0.219 0.325 0.137 0.407

Yellowstone 2003 0.339 0.165 0.174 0.136 0.203 0.089 0.250

Unit 2

Bridger 2001 1.952 0.983 0.969 0.804 1.148 0.531 1.421

Bridger 2002 1.575 0.787 0.788 0.653 0.922 0.441 1.134

Bridger 2003 1.859 0.956 0.903 0.796 1.063 0.543 1.316

Fitzpatrick 2001 0.853 0.422 0.431 0.344 0.509 0.216 0.637

Fitzpatrick 2002 0.619 0.299 0.320 0.249 0.370 0.163 0.456

Fitzpatrick 2003 0.709 0.340 0.369 0.276 0.433 0.181 0.528

N. Absaroka 2001 0.347 0.167 0.180 0.137 0.210 0.092 0.255

N. Absaroka 2002 0.344 0.185 0.159 0.158 0.186 0.112 0.232

N. Absaroka 2003 0.193 0.097 0.096 0.082 0.111 0.062 0.131

Washakie 2001 0.427 0.217 0.210 0.175 0.252 0.124 0.303

Washakie 2002 0.484 0.247 0.237 0.208 0.276 0.141 0.343

Washakie 2003 0.350 0.174 0.176 0.145 0.205 0.101 0.249

Teton 2001 0.511 0.261 0.250 0.215 0.296 0.146 0.365

Teton 2002 0.609 0.294 0.315 0.241 0.368 0.161 0.448

Teton 2003 0.406 0.202 0.204 0.169 0.237 0.108 0.298

Grand Teton 2001 0.603 0.295 0.308 0.243 0.360 0.156 0.447

Grand Teton 2002 0.932 0.458 0.474 0.375 0.557 0.234 0.698

Grand Teton 2003 0.421 0.208 0.213 0.171 0.250 0.121 0.300

Yellowstone 2001 0.518 0.262 0.256 0.219 0.299 0.146 0.372

Yellowstone 2002 0.536 0.285 0.251 0.244 0.292 0.176 0.360

Yellowstone 2003 0.354 0.172 0.182 0.142 0.212 0.095 0.259

Unit 3

Bridger 2001 2.222 2.051 0.171 1.559 0.663 0.761 1.461

Bridger 2002 1.838 1.695 0.143 1.291 0.547 0.694 1.144

Bridger 2003 2.391 2.220 0.171 1.693 0.698 0.878 1.513

Fitzpatrick 2001 1.144 1.057 0.087 0.816 0.328 0.400 0.744
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Fitzpatrick 2002 0.896 0.822 0.074 0.623 0.273 0.305 0.591

Fitzpatrick 2003 0.881 0.810 0.071 0.612 0.269 0.279 0.602

N. Absaroka 2001 0.542 0.499 0.043 0.380 0.162 0.188 0.354

N. Absaroka 2002 0.583 0.541 0.042 0.423 0.160 0.221 0.362

N. Absaroka 2003 0.288 0.266 0.022 0.205 0.083 0.115 0.173

Washakie 2001 0.808 0.746 0.062 0.575 0.233 0.291 0.517

Washakie 2002 0.775 0.712 0.063 0.542 0.233 0.267 0.508

Washakie 2003 0.589 0.541 0.048 0.405 0.184 0.197 0.392

Teton 2001 0.858 0.789 0.069 0.603 0.255 0.304 0.554

Teton 2002 0.962 0.884 0.078 0.665 0.297 0.307 0.655

Teton 2003 0.609 0.560 0.049 0.426 0.183 0.206 0.403

Grand Teton 2001 1.009 0.932 0.077 0.723 0.286 0.362 0.647

Grand Teton 2002 1.090 1.003 0.087 0.757 0.333 0.360 0.730

Grand Teton 2003 0.800 0.734 0.066 0.547 0.253 0.266 0.534

Yellowstone 2001 0.834 0.768 0.066 0.583 0.251 0.282 0.552

Yellowstone 2002 0.860 0.791 0.069 0.600 0.260 0.292 0.568

Yellowstone 2003 0.451 0.416 0.035 0.319 0.132 0.154 0.297

Table 16 – Model Results for PacifiCorp – Wyodak Units

Unit Class I Area

by Year

New Baseline Scenario 1 Scenario 2 Scenario 3

98th Percentile

Visibility Impact 

(∆dv)

98th Percentile

Visibility Impact 

(∆dv)

Visibility Improvement 

(∆dv)

98th Percentile

Visibility Impact 

(∆dv)

Visibility Improvement 

(∆dv)

98th Percentile

Visibility Impact 

(∆dv)

Visibility Improvement 

(∆dv)

Unit 1

Badlands 2001 0.579 0.455 0.124 0.389 0.190 0.243 0.336

Badlands 2002 0.746 0.613 0.133 0.539 0.207 0.299 0.447

Badlands 2003 0.706 0.536 0.170 0.479 0.227 0.285 0.421

Wind Cave 2001 0.840 0.648 0.192 0.558 0.282 0.322 0.518

Wind Cave 2002 0.958 0.751 0.207 0.637 0.321 0.365 0.593

Wind Cave 2003 1.138 0.896 0.242 0.762 0.376 0.431 0.707
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Table 17 – Model Results for Basin Electric – Laramie River Station Units

Unit Class I Area

by Year

New Baseline Scenario 1 Scenario 2 Scenario 3

98th Percentile

Visibility Impact 

(∆dv)

98th Percentile

Visibility Impact 

(∆dv)

Visibility Improvement 

(∆dv)

98th Percentile

Visibility Impact 

(∆dv)

Visibility Improvement 

(∆dv)

98th Percentile

Visibility Impact 

(∆dv)

Visibility Improvement 

(∆dv)

Unit 1

Badlands 2001 1.278 0.993 0.285 0.840 0.438 0.489 0.789

Badlands 2002 0.738 0.582 0.156 0.504 0.234 0.297 0.441

Badlands 2003 1.051 0.820 0.231 0.684 0.367 0.327 0.724

Wind Cave 2001 1.038 0.838 0.200 0.721 0.317 0.399 0.639

Wind Cave 2002 1.077 0.888 0.189 0.778 0.299 0.486 0.591

Wind Cave 2003 0.788 0.618 0.170 0.531 0.257 0.331 0.457

Rawah 2001 0.322 0.269 0.053 0.231 0.091 0.125 0.197

Rawah 2002 0.555 0.454 0.101 0.395 0.160 0.239 0.316

Rawah 2003 0.351 0.300 0.051 0.270 0.081 0.163 0.188

RMNP 2001 0.408 0.318 0.090 0.267 0.141 0.154 0.254

RMNP 2002 0.603 0.481 0.122 0.416 0.187 0.262 0.341

RMNP 2003 0.590 0.472 0.118 0.404 0.186 0.219 0.371

Unit 2

Badlands 2001 1.194 0.895 0.299 0.776 0.418 0.461 0.733

Badlands 2002 0.685 0.532 0.153 0.464 0.221 0.284 0.401

Badlands 2003 0.974 0.734 0.240 0.614 0.360 0.312 0.662

Wind Cave 2001 0.978 0.769 0.209 0.666 0.312 0.377 0.601

Wind Cave 2002 1.031 0.831 0.200 0.734 0.297 0.475 0.556

Wind Cave 2003 0.739 0.562 0.177 0.498 0.241 0.321 0.418

Rawah 2001 0.307 0.248 0.059 0.213 0.094 0.119 0.188

Rawah 2002 0.521 0.417 0.104 0.366 0.155 0.229 0.292

Rawah 2003 0.327 0.275 0.052 0.250 0.077 0.154 0.173

RMNP 2001 0.379 0.287 0.092 0.242 0.137 0.147 0.232

RMNP 2002 0.580 0.450 0.130 0.386 0.194 0.251 0.329

RMNP 2003 0.551 0.429 0.122 0.370 0.181 0.203 0.348

Unit 3

Badlands 2001 1.141 0.923 0.218 0.810 0.331 0.472 0.669

Badlands 2002 0.733 0.577 0.156 0.493 0.240 0.299 0.434

Badlands 2003 0.896 0.696 0.200 0.593 0.303 0.309 0.587

Wind Cave 2001 0.988 0.787 0.201 0.683 0.305 0.389 0.599
15

Wind Cave 2002 0.993 0.800 0.193 0.702 0.291 0.461 0.532

Wind Cave 2003 0.728 0.583 0.145 0.496 0.232 0.336 0.392

Rawah 2001 0.314 0.258 0.056 0.227 0.087 0.144 0.170

Rawah 2002 0.533 0.432 0.101 0.380 0.153 0.241 0.292

Rawah 2003 0.348 0.296 0.052 0.269 0.079 0.166 0.182

RMNP 2001 0.392 0.301 0.091 0.255 0.137 0.162 0.230

RMNP 2002 0.584 0.473 0.111 0.417 0.167 0.276 0.308

RMNP 2003 0.555 0.438 0.117 0.379 0.176 0.220 0.335