Air Quality Modeling Protocol: Wyoming Regional Haze Federal 

Implementation Plan

January 2014

U.S. Environmental Protection Agency

Region 8

Denver, CO 80202
i

Table of Contents

1.0 INTRODUCTION................................................................................................. 1

2.0 BACKGROUND................................................................................................... 1

3.0 MODELING APPROACH............................................................... 2

3.1 Emission Sources.................................................................. 3

3.2 Class I Areas........................................................................ 3

3.3 Pollutants to Consider.............................................................. 4

3.4 Natural Background............................................................... 4

3.5 Visibility Calculation............................................................... 5

4.0 EMISSIONS DATA FOR MODELING................................................................ 6

4.1 Baseline Modeling....................................................................................... 6

4.2 Post-Control Modeling................................................................................ 7

4.3 Emission Model Scenarios........................................................ 7

5.0 MODELING SYSTEM....................................................................................... 8

5.1 CALMET.................................................................................................... 9

5.2 CALPUFF............................................................................ 12

5.2.1 Background Ozone Concentrations..................................... 12

5.2.2 Background Ammonia Concentrations................................. 13

5.2.3 Receptor Locations........................................................ 13

5.3 POST-PROCESSING............................................................. 14

5.3.1 POSTUTIL................................................................. 14

5.3.2 CALPOST.................................................................. 15

6.0 PRESENTATION OF RESULTS AND REPORTING........................... 15

APPENDIX A – BACKGROUND CONDITIONS ASSUMED FOR MODELING...... 17

APPENDIX B – EMISSION ASSUMPTIONS FOR MODELING.......................... 19

APPENDIX C – CALMET CONTROL FILE INPUTS........................................ 25

APPENDIX D – CALPUFF CONTROL FILE INPUTS....................................... 26

APPENDIX E – CLASS I RECEPTOR DOMAINS............................................ 27

APPENDIX F – CALPOST CONTROL FILE INPUTS....................................... 33

APPENDIX G – POSTUTIL CONTROL FILE INPUTS....................................... 34

APPENDIX H – VISIBILITY IMPACT RESULTS............................................ 35
1

1.0 INTRODUCTION 

In 2005, the U.S. EPA issued final amendments to the Regional Haze Regulations and 

Guidelines and published the Guidelines for Best Available Retrofit Technology (BART) 

Determinations.1 Along with other requirements, the Guidelines address the methodology for 

determining which sources must apply BART and the evaluation of control options. In particular, 

the Guidelines state that the CALPUFF modeling system (or another appropriate dispersion 

models approved by EPA) should be used to predict the visibility improvement expected at a 

Class I area from potential BART control technologies applied to a single source. The Guidelines 

also recommend developing a modeling protocol that outlines the model approach.

In accordance with EPA Guidelines, EPA Region 8 used the CALPUFF model to predict the 

visibility impacts from several Wyoming electric generating units (EGUs) that are subject-toBART and reasonable progress and to evaluate various control options. This air quality modeling 

protocol documents the methodology used to conduct the air quality dispersion modeling and the 

approach to determine the improvement in visibility to be achieved by BART and reasonable 

progress controls. This protocol does not explain how the visibility results are factored into the 

BART and reasonable progress determination process. Information related to the BART and 

reasonable progress determination process appears in the Federal Register notice and elsewhere 

in the Docket. All EPA Region 8 modeling files used for this effort are available upon request. 

Contact Rebecca Matichuk at matichuk.rebecca@epa.gov. 

This document is organized as follows:

 Section 2.0 – Background 

 Section 3.0 – Modeling Approach

 Section 4.0 – Emissions Data for Modeling

 Section 5.0 – Modeling System

 Section 6.0 – Presentation of Results and Reporting

2.0 BACKGROUND

In January 2011, the State of Wyoming submitted a regional haze State Implementation Plan 

(SIP)2to the EPA Region 8. As part of the regional haze SIP, the State of Wyoming and BART 

sources used a modeling protocol that was developed and adopted by the State of Wyoming in 

September 2006.

3

The State of Wyoming modeling protocol specified an approach for using the 

CALPUFF modeling system to evaluate BART visibility impacts and determine the 

improvement in visibility to be achieved by BART controls. The emission rates used in the 

CALPUFF modeling were also determined by Wyoming. These emission rates were based on

existing permits, allowable rates, and emissions reporting data. For the subject-to-BART 

PacifiCorp sources, the analyses completed by the State of Wyoming provided modeling results 

 

1

70 FR 39104 (July 6, 2005). BART Guidelines, 40 CFR Part 51, Appendix Y.

2

309(g) Wyoming State Implementation Plan, Regional Haze, Addressing Regional Haze Requirements for 

Wyoming Mandatory Federal Class I Areas Under 40 CFR 51.309(g), Wyoming Department of Environmental 

Quality, Air Quality Division, EPA-R08-OAR-2012-0026, January 7, 2011.

3 BART Air Modeling Protocol Individual Source Visibility Impairment Analysis, State of Wyoming, Department of 

Environmental Quality, Air Quality Division, September 2006.
2

that combine the visibility improvement from Nitrogen Oxides (NOx), Particulate Matter (PM), 

and Sulfur Dioxide (SO2) control options.

In June 2012, EPA Region 8 published a proposed rule on Wyoming’s regional haze 309(g) SIP 

submittal.

4

For reasons explained in the EPA Region 8 proposed action, EPA Region 8 

performed additional modeling for this proposed rule to determine visibility improvements from 

individual NOx controls that the State of Wyoming and BART sources had not evaluated 

individually in the original SIP.5,6 EPA Region 8 followed the State’s modeling protocol for 

using the CALPUFF modeling system to evaluate visibility impacts of the individual NOx

controls that were not analyzed by the State of Wyoming and BART sources.

In June 2013, EPA Region 8 published a revised proposed rule partially approving and partially 

disapproving Wyoming’s 40 CFR 51.309(g) regional haze SIP.7 As explained in the June 2012 

proposed notice, EPA Region 8 had performed additional modeling of NOx control scenarios for 

both BART and reasonable progress sources that were not analyzed by the State of Wyoming 

and BART sources. However, for reasons explained in the June 2013 notice, EPA Region 8 

revised the emissions data for the baseline period and all emissions control technologies, and 

then updated the modeling analyses for the revised proposed rule published in June 2013.8,9,10,11 

EPA Region 8 also continued to follow the State’s modeling protocol for the other aspects of the 

modeling performed for the revised proposal.

For reasons explained in the final notice for this action, EPA Region 8 developed a new 

modeling protocol. This modeling protocol documents the EPA Region 8 updated approach for 

remodeling the individual NOx baseline and control technology scenarios for several Wyoming 

BART and reasonable progress EGUs with the most current EPA-approved modeling system and 

guidance and more representative background ammonia concentrations. As presented in this 

protocol and in the final Federal Register notice for this action, several input parameters were 

evaluated and selected based on procedures and recommendations outlined in EPA-accepted 

modeling guidance and available data. EPA Region 8 also conferred with other EPA modeling 

experts to ensure that the modeling would be done in accordance with applicable guidance for 

visibility impairment analysis.

Additional details of the EPA Region 8 decisions related to the modeling are discussed below 

and in the final Federal Register notice for this action. 

3.0 MODELING APPROACH

This section describes the components and information required for the CALPUFF modeling.

Each source that causes or contributes to visibility impairment in one or more Class I area must 

conduct a BART analysis to define the best available retrofit technology applicable to that 

 

4

77 FR 33022 (June 4, 2012).

5 Revised Summary of EPA’s Modeling, EPA-R08-OAR-2012-0026-0037, 07/10/2012.

6 EPA BART and RP Modeling for Wyoming Sources, EPA-R08-OAR-2012-0026-0021, 06/04/2012.

7

78 FR 34738 (June 10, 2013).

8

Summary of EPA’s Revised Modeling, EPA-R08-OAR-2012-0026-0082, 01/08/2013.

9 EPA’s Revised Modeling Results for Wyoming, EPA-R08-OAR-2012-0026-0083, 01/08/2013.

10 Summary of EPA’s Revised Modeling – Including Revisions from Previous Version Posted on 1/18/2013 and 

Results for Jim Bridger Units 1-4, EPA-R08-OAR-2012-0026-0088, 02/11/2013.

11

 EPA’s Revised Modeling Result for Wyoming, EPA-R08-OAR-2012-0026-0089, 02/11/2013.
3

source, and quantify the visibility improvement at the Class I areas associated with BART 

controls. This section covers the following elements: emission sources; Class I area 

identification; pollutants considered; natural background conditions; visibility impairment 

determination; and the analysis process.

3.1 Emission Sources

The sources that EPA Region 8 remodeled are listed in Table 1. EPA Region 8 also performed 

additional modeling for units 1 and 2 of the PacifiCorp - Dave Johnston Power Plant. These are 

considered reasonable progress sources.

Table 1. Wyoming BART and Reasonable Progress Sources Modeled by EPA

Company Name Plant Name Units

Basin Electric Laramie River Power Plant Boilers #1,2,3 

PacifiCorp Dave Johnson Power Plant Boilers #1,2,3,4 

PacifiCorp Jim Bridger Power Plant Boilers #1,2,3,4

PacifiCorp Naughton Power Plant Boilers #1,2,3 

PacifiCorp Wyodak Power Plant Boiler 

3.2 Class I Areas

EPA Region 8 determined the Class I areas to be included in the modeling based Class I areas 

included in prior modeling by the State of Wyoming and by the distance of each source to Class I 

area. The federal Class I areas that were modeled previously and are located within 300 km of 

the Wyoming sources are listed in Table 2. Figure 1 is a map that presents the location of the 

modeled Class I areas in relation to the Wyoming sources. Visibility improvement at these Class 

I areas will provide the best measure of the effectiveness of BART and reasonable progress 

controls. This approach is consistent with the BART Guidelines.

Table 2. Source-Specific Federal Class I Areas Selected for Modeling

Source Class I Areas to be Evaluated 

Basin Electric 

Laramie River Power Plant

Badlands National Park, Rawah Wilderness Area, Rocky 

Mountain National Park, Wind Cave National Park

PacifiCorp 

Dave Johnston Power Plant

Badlands National Park, Mt. Zirkel Wilderness Area, Rawah 

Wilderness Area, Rocky Mountain National Park, Wind Cave 

National Park 

PacifiCorp

Jim Bridger Power Plant

Bridger Wilderness Area, Fitzpatrick Wilderness Area, Grand 

Teton National Park, Mt. Zirkel Wilderness Area, Rawah 

Wilderness Area, Rocky Mountain National Park, Teton 

Wilderness Area, Washakie Wilderness Area, Yellowstone 

National Park

PacifiCorp 

Naughton Power Plant 

Bridger Wilderness Area, Fitzpatrick Wilderness Area, Grand 

Teton National Park, North Absaroka Wilderness Area, Teton 

Wilderness Area, Washakie Wilderness Area, Yellowstone 

National Park

PacifiCorp 

Wyodak Power Plant Badlands National Park, Wind Cave National Park
4

Figure 1. Source Locations in Proximity to Class I Areas

3.3 Pollutants to Consider

The BART Guidelines state that modeling should be conducted for sulfur dioxide (SO2), nitrogen 

oxides (NOx) and direct particulate matter (PM) emissions, including both PM10 and PM2.5. All 

of the pollutants were included in the modeling; however, as mentioned above, the modeling will 

only evaluate the baseline and NOx control scenarios for BART and Reasonable Progress 

sources. The emissions data and emissions assumptions are discussed in more detail in Section 

4.0 below.

3.4 Natural Background

The FLAG 2010 guideline lists two sets of Natural Conditions corresponding to Annual Average

and 20 percent best natural days. To represent natural visibility background in the Class I areas, 

the values associated to the 20 percent best natural days were used, in lieu of the values 

associated to the annual average natural days. This approach is consistent with the previous 

BART modeling conducted for the sources. This definition of natural background is also

consistent with the BART Guideline.

12 The specific natural background values used in this 

protocol were drawn from the FLAG 2010 guideline. Class I area specific natural background

assumptions are presented in Appendix A.

 

12 70 FR 39124.
5

3.5 Visibility Calculation

The methodology for performing visibility calculations with the CALPUFF modeling system is 

described in several documents, including: 

 Interagency Workgroup on Air Quality Modeling (IWAQM) Phase 2 Summary Report 

and Recommendations for Modeling Long Range Transport Impacts,

13

 Federal Land Manager’s Air Quality Related Values Workgroup (FLAG): Phase I 

Report,

14 and

 A User's Guide for the CALPUFF Dispersion Model.

15

The CALPUFF modeling techniques presented in this protocol provide ground level

concentrations of visibility impairing pollutants. The concentration estimates from CALPUFF

were used with the FLAG 2010 referenced IMPROVE equation16 to calculate the extinction 

coefficient (bext), as shown below.

bext = 2.2 × fS(RH) × [Small Sulfate] + 4.8 × fL(RH) × [Large Sulfate]

• 2.4 × fS(RH) × [Small Nitrate] + 5.1 × fL(RH) × [Large Nitrate]

• 2.8 × [Small Organic Mass] + 6.1 × [Large Organic Mass]

• 10 × [Elemental Carbon]

• 1 × [Fine Soil]

• 0.6 × [Coarse Mass]

• 1.7 × fSS(RH) × [Sea Salt]

• Rayleigh Scattering (Site Specific)

• 0.33 × [NO2 (ppb)] {or as: 0.1755 × [NO2 (μg/m3)]}

Where:

[ ] indicates concentrations in μg/m3

fS(RH) = Relative humidity adjustment factor for small sulfate and nitrate

fL(RH) = Relative humidity adjustment factor for large sulfate and nitrate

fSS(RH) = Relative humidity adjustment factor for sea salt

For Total Sulfate < 20 μg/m3:

[Large Sulfate] = ([Total Sulfate] / 20 μg/m3) × [Total Sulfate]

For Total Sulfate ≥ 20 μg/m3:

[Large Sulfate] = [Total Sulfate]

And:

[Small Sulfate] = [Total Sulfate] – [Large Sulfate]

To calculate large and small nitrate and organic mass, substitute ({Large, Small, Total}

{Nitrate, Organic Mass}) for Sulfate.

The change in visibility for the BART analyses is the 98th percentile deciview change relative to 

the 20 percent best days natural background conditions.17,18 The delta-deciview (Δdv) value is

 

13 Interagency Workgroup on Air Quality Modeling (IWAQM) Phase 2 Summary Report and Recommendations for 

Modeling Long Range Transport Impacts, Office of Air Quality Standards, EPA-454/R-98-019, December 1998.

14 Federal Land Managers’ Air Quality Related Values Workgroup (FLAG) 2008. Phase I Report—Revised (2010).

15 Scire J.S., D.G. Strimaitis, R.J. Yamartino. “A User's Guide for the CALPUFF Dispersion Model.” Earth Tech, 

Concord, MA, January 2000.

16 Federal Land Managers’ Air Quality Related Values Workgroup (FLAG) 2008. Phase I Report—Revised (2010).

17 70 FR 39119, 39121, 39170.
6

calculated from the source’s contribution to extinction, bext (source), and background extinction,

bext(bkg), as follows:

Δdv = 10 ln ( bext(bkg) + bext (source) ) / bext(bkg) )

19

The monthly relative humidity adjustment factors from the above equation and all background 

assumptions used in the modeling are included in Appendix A.

4.0 EMISSIONS DATA FOR MODELING

CALPUFF model inputs require source parameters, including pollutant emission rates and stack 

data (location, height, diameter, exit gas temperature, and exit gas velocity). In accordance with 

BART Guidelines, the baseline (pre-control) emission rates represented the 24-hour average 

actual emission rate from the highest emitting day of the meteorological period modeled.

20 The 

post-control emission rates were calculated as a percentage of pre-control emission rates. This 

approach is also in accordance with the BART Guidelines. For this modeling, the emissions data 

are the same as the modeling performed for the revised proposal published in June 2013, which 

includes the maximum 24-hour average actual emission rate for the meteorological period 

modeled. The details of the emissions data used in the modeling are discussed below.

4.1 Baseline Modeling 

The emission rates and stack data for the sources listed in Table 1 were determined in the 

previous modeling for the proposed rule published in June 2013.

21 Briefly, the baseline NOx

emission rates were derived from the highest daily rates for 2001-2003, as found in the EPA 

Clean Air Markets Division (CAMD) emissions system.

22 For other pollutants, such as SO2 and 

PM, the baseline emission inputs were derived from the State of Wyoming BART Application 

Analyses.

23,24,25,26,27

 

 

18 Guidance for Estimating Natural Visibility Conditions Under the Regional Haze Rule, Office of Air Quality 

Planning and Standards, Emissions, Monitoring and Analysis Division, Air Quality Trends Analysis Group, EPA454/B-03-005, September 2003.

19 Federal Land Managers’ Air Quality Related Values Workgroup (FLAG) 2008. Phase I Report—Revised (2010).

20 70 FR 39170.

21 Summary of EPA’s Revised Additional Visibility Improvement Modeling for Wyoming’s 309(g) SIP, EPA-R08-

OAR-2012-0026-0082, December 13, 2012.

22 WY Daily Emission Rates 2001 to Mid 2003, EPA-R08-OAR-2012-0026-0091, May 23, 2012.

23 Attachment A: BART Applications and AQD Analyses: PacifiCorp – Naughton, EPA-R08-OAR-2012-0026-

0009, 06/04/2012.

24 Attachment A: BART Applications and AQD Analyses: Basin Electric – Laramie River Station, EPA-R08-OAR2012-0026-0003, 06/04/2012.

25 Attachment A: BART Applications and AQD Analyses: PacifiCorp – Wyodak, EPA-R08-OAR-2012-0026-0010, 

06/04/2012.

26 Attachment A: BART Applications and AQD Analyses: PacifiCorp – Dave Johnston, EPA-R08-OAR-2012-0026-

0007, 06/04/2012.

27 Attachment A: BART Applications and AQD Analyses: PacifiCorp – Jim Bridger, EPA-R08-OAR-2012-0026-

0008, 06/04/2012.
7

EPA Region 8 also performed additional modeling for units 1 and 2 of the PacifiCorp - Dave 

Johnston Power Plant.

28 These are considered Reasonable Progress sources. For these sources, 

baseline NOx emission rates were established in the same manner as for the BART sources. 

Baseline emission rates for other pollutants were based on the source’s Title V operating permit, 

which are in the docket for this final action.

 Stack parameter data for these units were obtained 

from the Western Region Air Partnership’s (WRAP) 2002 Sparse Matrix Operator Kernel 

Emissions (SMOKE) modeling system input files.29

4.2 Post-Control Modeling

As explained further in the notice for the final action, post-control emissions for NOx were 

determined by multiplying the baseline emissions by the percent reduction associated with the

BART control. For this modeling, EPA Region 8 modeled the NOx emissions scenarios that 

were not evaluated by the State of Wyoming in order to isolate the impact of different NOx

control technologies. As with the baseline modeling, the inputs for other pollutants, such as SO2

and PM, were derived from the State of Wyoming BART Application Analyses, which are in the 

docket for this final action. The modeling for the EPA Region 8 control scenarios utilized the

emission and stack parameter assumptions from the “Post-Control Scenario A” case of the 

Wyoming BART Application Analyses.

4.3 Emission Model Scenarios

EPA Region 8 developed one baseline scenario (referenced as Baseline) and three control 

scenarios (referenced as Scenario 1, Scenario 2, and Scenario 3) to model for each BART and 

Reasonable Progress source listed in Table 1. The Baseline scenario reflects the baseline 

emission rates. Scenario 1 reflects the visibility improvement from Low-NOxBurners (LNB) 

with Over-fire Air (OFA) controls. Scenario 2 reflects the visibility improvement from 

LNB/OFA and Selective Non-Catalytic Reduction (SNCR) controls. Scenario 3 reflects the 

visibility improvement from LNB/OFA and Selective Catalytic Reduction (SCR) controls. The 

only differences in the control scenarios are the emission rates for NOx and the total sulfate 

emission rates in the SCR scenario (Scenario 3). For the SCR scenario, or Scenario 3, total 

sulfate rates were increased to account for the additional production that results from the SCR 

controls. As seen in the tables presented in Appendix B, the NOx emission rates were varied 

across the different control scenarios, while the other input parameters were held constant. 

Table 3 below summarizes the descriptions of the EPA Region 8 baseline and control scenarios. 

The baseline and control scenario emission assumptions used in the updated modeling for the 

Wyoming sources listed in Table 1 are presented in Appendix B.

 

28 Attachment A: BART Applications and AQD Analyses: PacifiCorp – Dave Johnston, EPA-R08-OAR-2012-0026-

0007, 06/04/2012.

29 February 28, 2011 TSD for Technical Products Prepared by the WRAP in Support of the Western Regional Haze 

Plans, EPA-R08-OAR-2012-0026-0020, 06/04/2012.
8

Table 3. Description of EPA Control Scenarios for Wyoming BART Sources

EPA Scenario Description

BART Sources

Baseline Post-Control Scenario A from State‘s BART Application Analysis but with NOx 

emission rate that reflects the highest daily rate

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

emission rate that reflects LNB/OFA controls

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

emission rate that reflects LBN/OFA and SNCR controls

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

emission rate that reflects LNB/OFA and SCR controls

Reasonable Progress Sources 

Baseline Inputs obtained from facility’s Title V Operating Permit limits but with NOx

emission rate that reflects the highest daily rate

Scenario 1 Same inputs as Baseline but with a NOx emission rate that reflects LNB/OFA 

controls

Scenario 2 Same inputs as Baseline but with a NOx emission rate that reflects LNB/OFA and 

SNCR controls

Scenario 3 Same inputs as Baseline but with a NOx emission rate that reflect LNB/OFA and 

SCR controls

5.0 MODELING SYSTEM

The visibility impact modeling used the CALPUFF suite of programs, and followed the 

procedures and recommendations outlined in applicable documents. For the most part, the 

regulatory default options were utilized for the CALPUFF modeling. Details are provided below 

for the non-default options selected for this modeling. The requirements and recommendations 

outlined in the documents listed below were also followed:

 EPA’s Guidance for Estimating Natural Visibility Conditions under the Regional Haze 

Rule, 30

 Appendix W of 40 CFR Part 51, Guideline on Air Quality Models,

31

 Interagency Workgroup on Air Quality Modeling Phase 2 report,32

 Federal Land Managers’ Air Quality Related Values Workgroup – Phase I Report,

33

 User's Guide for the CALPUFF Dispersion Model,

34 and

 State of Wyoming BART Modeling Protocol.

35

 

30 Guidance for Estimating Natural Visibility Conditions Under the Regional Haze Rule, Office of Air Quality 

Planning and Standards, Emissions, Monitoring and Analysis Division, Air Quality Trends Analysis Group, EPA454/B-03-005, September 2003.

31 Appendix W, 40 CFR Part 51: Revision to the Guideline on Air Quality Models: Adoption of a Preferred General 

Purpose (Flat and Complex Terrain) Dispersion Model and Other Revisions; Final Rule, Vol. 70, No. 216, 68218-

68261, November 9, 2005.

32 Interagency Workgroup on Air Quality Modeling (IWAQM) Phase 2 Summary Report and Recommendations for 

Modeling Long Range Transport Impacts, Office of Air Quality Standards, EPA-454/R-98-019, December 1998.

33 Federal Land Managers’ Air Quality Related Values Workgroup (FLAG) 2008. Phase I Report—Revised (2010).

34 Scire J.S., D.G. Strimaitis, R.J. Yamartino. “A User's Guide for the CALPUFF Dispersion Model.” Earth Tech, 

Concord, MA, January 2000.

35 BART Air Modeling Protocol Individual Source Visibility Impairment Analysis, State of Wyoming, Department 

of Environmental Quality, Air Quality Division, September 2006.
9

Tables listing the specific modeling parameters for each CALPUFF module are located in the 

Appendices.

The individual CALPUFF modules of the CALPUFF modeling system and the version numbers

used in the updated modeling are presented in Table 4. With the exception of the CALMET 

processor, the regulatory versions approved at the time of the modeling and default options of the 

CALPUFF modeling system were used for the updated modeling. The meteorological data 

provided by the State of Wyoming were still used in the updated modeling.

36 Compared to the 

previous modeling performed by EPA Region 8 for the 2012 proposal, the main differences in 

the updated modeling include the model versions and associated model default options for 

CALPUFF, CALPOST, and POSTUTIL. The updated modeling also changed the treatment of 

background ammonia concentrations. These differences are explained in more detail below.

Table 4. CALPUFF Modeling System

Program Version Level

CALMET 5.53a 040716

CALPUFF 5.837 070623

CALPOST 6.221 080724

POSTUTIL 1.56 070627

5.1 CALMET

CALMET is a diagnostic wind model that develops hourly wind and temperature fields in a 

three-dimensional, gridded modeling domain. Meteorological inputs to CALMET can include 

surface and upper-air observations from multiple meteorological monitoring stations. The 

CALMET model can also utilize gridded analysis fields from various mesoscale models, such as

the Fifth-Generation Penn State/NCAR Mesoscale Model (MM5), to better represent regional 

wind flows and complex terrain circulations. 

The MM5/CALMET meteorological fields were provided by the State of Wyoming for 2001, 

2002, and 2003.38 At the time these meteorological fields were generated, the EPA-Approved or 

regulatory version of the CALMET model was version 5.53a (040716), which was released in 

2005. Figure 2 and Figure 3 show the CALMET model domain and the locations of the 

meteorological observations that were input to CALMET, including surface, upper-air, and 

precipitation stations. The model domain covered by the State of Wyoming meteorological data

is centered in southwest Wyoming, and extends roughly from Twin Falls, Idaho in the west to 

the Missouri River in the east, and from Denver in the south to Helena, Montana in the north.

The MM5 data used by the State of Wyoming had a resolution of 12-km. For most of the 

 

36 EPA Region 8 did not update the CALMET modeling platform due to the level of resources needed to regenerate 

the meteorological data, and the updates incorporated into the most recent CALMET module were not expected to 

significantly impact the model results. The impacts of the updates incorporated into the most recent CALMET are 

discussed in “Assessment of the “VISTAS” Version of the CALPUFF Modeling System” (EPA, August 2008). 

37 In accordance with the Guideline on Air Quality Models (“GAQM”, 40 CFR 51, Appendix W, section 6.2.1.e), 

EPA Region 8 used the most recent EPA-approved version of CALPUFF. When the modeling was being completed 

in August 2013, the most recent version of CALPUFF was version 5.8 (level 070623) [Model Change Bulletin D, 

June 23, 2007]. CALPUFF version 5.8 (070623) was released on June 29, 2007 and considered the “EPAApproved” or regulatory version. 

38 Tonnesen et al., CALMET/CALPUFF Protocol for BART Exemption Screening Analysis for Class I Areas in the 

Western United States, Western Regional Air Partnership, Western Governors’ Association; August 15, 2006. The 

CALMET input data are in the docket available upon request. 
10

technical options, default settings were used in the CALMET input files. Table 5 lists the key 

user-defined CALMET settings that were selected, and Appendix C presents the CALMET 

Control File inputs.

EPA Region 8 did not regenerate the meteorological data using the most recent CALMET 

module (version 5.8). Instead, EPA Region 8 continued to use the meteorological data provided 

by the State of Wyoming for years 2001 to 2003. EPA Region 8 relied on the meteorological 

data generated from the CALMET model released in 2005 (version 5.53a) because of the level of 

resources needed to regenerate the data and there is no evidence that the updates incorporated 

into the current, approved regulatory version of CALMET (version 5.8) would have substantially 

affected the model results.39

Figure 2. Surface and Upper Air Stations – Observations Input to CALMET

 

39 Assessment of the “VISTAS” Version of the CALPUFF Modeling System, EPA, August 2008.

LEGEND

 CALMET Domain UA Upper Air Stations

ASOS Surface Stations Domain Dimensions: 1060 x 780 KM
11

Figure 3. Observations Input for CALMET Modeling

Table 5. Key User-Defined CALMET Settings

Variable Description Value

PMAP Map Projection LCC (Lambert Conformal Conic)

DGRIDKM Grid Spacing (km) 4

NZ Number of Layers 10

ZFACE Cell Face Heights (m) 0, 20, 40, 100, 140, 320,

580, 1020, 1480, 2220, 3500

RMIN2 Minimum Distance for Extrapolation -1

IPROG Use Gridded Prognostic Model Output 14 (MM5 Data)

RMAX 1 Maximum Radius of Influence (surface layer, km) 30

RMAX 2 Maximum Radius of Influence (layers aloft, km) 50

TERRAD Radius of Influence for Terrain (km) 15

R1 Relative Weighting of First Guess Wind Field and 

Observations (km) 5

R2 Relative Weighting Aloft (km) 25
12

5.2 CALPUFF

The CALPUFF model was used with each of the three years of meteorological data to calculate 

pollutant concentrations at receptors in multiple Class I areas for all units and control scenarios.

In general, the application of CALPUFF uses the regulatory default options and follows the 

procedures and recommendations outlined in applicable documents. Details of the parameter 

settings in CALPUFF are provided in Appendix D. However, the major features are outlined

below.

 Building downwash effects were not included because of the transport distances involved

did not generally include buildings and the fact that most sources have tall stacks.40 Thus, 

building downwash is unlikely to have a significant effect on model-predicted 

concentrations. 

 Puff splitting was not used, following the recommendations outlined in the IWAQM 

Phase 2 report.

41

 Hourly ozone files were used to define background ozone concentration.42 Data were 

available from the following sites within the model domain. 

o Rocky Mountain NP, CO 

o Craters of the Moon NP, ID 

o AIRS – Highland UT 

o Mountain Thunder, WY 

o Yellowstone NP, WY 

o Centennial, WY 

o Pinedale, WY 

 The background ozone concentration shown in Appendix D (BCKO3 = 44 ppb) was used 

only when hourly data were missing. 

 The background ammonia concentrations were based on monitoring data and the

IWAQM guidance. A discussion of the background ammonia concentration is included 

below and in the final Federal Register notice section on Modeling.

 MESOPUFF II chemical transformation rates were used. 

 The species modeled were the seven identified in CALPUFF: SO2, SO4, NOx, HNO3, 

NO3, PM2.5, and PM10. 

 Pasquill-Gifford Dispersion Coefficients for rural areas were used because the area in the 

modeling domains is rural.

 All units of each source were modeled separately for each model scenario or control 

scenario and meteorological year.

5.2.1 Background Ozone Concentrations

As specified in the State of Wyoming modeling protocol, the background ozone was only 

assumed at an annual constant level of 44.0 ppb when hourly data were missing.

 

40 Stack height data are presented in Appendix B of this Protocol.

41 Interagency Workgroup on Air Quality Modeling (IWAQM) Phase 2 Summary Report and Recommendations for 

Modeling Long Range Transport Impacts, Office of Air Quality Standards, EPA-454/R-98-019, December 1998.

42 Data were provided by the State of Wyoming. This data is in the docket and can be made available upon request.
13

5.2.2 Background Ammonia Concentrations

The CALPUFF model requires input data to specify representative monthly background 

ammonia concentrations for use in the transformation of gaseous nitric acid to particulate 

ammonium nitrate and also for the formation of particulate ammonium sulfate. For the reasons 

explained in the notice of the final action, EPA Region 8 evaluated background ammonia 

concentrations in the updated CALPUFF modeling as a result of comments received on the EPA 

Region 8 revised proposal published in June 2013.

EPA Region 8 developed three sets of background ammonia concentrations for the updated 

modeling. One set of the background ammonia concentrations used in the CALPUFF modeling

relied on data collected from a monitoring site located in Boulder, Wyoming (referenced as Set 

#1 Scenario). Another set of background concentrations relied on the IWAQM default ammonia 

value for forested areas (referenced as Set #2 Scenario). The third set of background 

concentrations relied on the IWAQM default ammonia value for arid areas (referenced as Set #3 

Scenario). Each set of background ammonia assumptions used in the updated modeling is 

discussed below and presented in Table 7.

For the updated modeling, EPA Region 8 performed two model simulations for each BART 

source located in western Wyoming (i.e., PacifiCorp’s Naughton and Jim Bridger power plants), 

and one model simulation for each BART and reasonable progress source in eastern Wyoming 

(i.e., Basin Electric Laramie River Power Plant and PacifiCorp’s Dave Johnston and Wyodak 

power plants). For the sources located in western Wyoming, EPA Region 8 performed one 

simulation that used the monitoring data (Set #1 Scenario) and another simulation that used the

IWAQM default value for forested areas (Set #2 Scenario). For the sources in eastern Wyoming, 

EPA Region 8 performed one simulation that used the IWAQM default value for arid areas (Set 

#3 Scenario). 

Table 7. Background Ammonia Concentrations [ppb] Assumed for Each Source43

Scenario Source Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Set #1

Boulder 

Monitor

PacifiCorp 

Naughton 0.36 0.36 0.48 0.54 0.59 0.73 1.18 1.12 0.84 0.55 0.41 0.38

PacifiCorp 

Jim Bridger 0.36 0.36 0.48 0.54 0.59 0.73 1.18 1.12 0.84 0.55 0.41 0.38

Set #2

IWAQM

[forests]

PacifiCorp 

Naughton 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5

PacifiCorp 

Jim Bridger 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5

Set #3

IWAQM

[arid]

PacifiCorp 

Dave Johnston 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0

Basin Electric 

Laramie River 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0

PacifiCorp 

Wyodak 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0

5.2.3 Receptor Locations

Predicted visibility impacts were computed at a set of gridded receptor locations for the Class I

 

43 Monthly average NH3 concentrations estimated by EPA were based on data from Molenar et al.,“NH3 Monitoring 

in the Upper Green River Basin”.
14

areas within the area considered for this modeling. These data are in Appendix E, and were

downloaded from the National Park Service website.

44

5.3 POST-PROCESSING

Visibility impacts were calculated from the CALPUFF concentration results using POSTUTIL 

and CALPOST. POSTUTIL was used to repartition total nitrate by accounting for ammonialimiting conditions. The output from CALPOST provides the highest deciview impacts on each 

day from all receptors within each Class I area modeled. Details of the parameter settings in 

CALPOST and POSTUTIL are provided in Appendix F and G, respectively, with some of the 

major features summarized below:

 For the visibility calculation, Method 8, Mode 5 (MVISBK=8, M8_MODE=5) was 

employed. This method uses monthly average relative humidity and f(RH) values for 

each Class I area, which are based on data from FLAG 2010.

 Particulate species for the visibility analysis included SO4, NO3, EC, OC, PM2.5, and

PM10.

 Natural background extinction calculations used the 20 percent best natural days for each

Class I area considered for this modeling. The values assumed for the 20 percent best 

natural days are included in Appendix A.

 Tables providing the monthly relative humidity adjustment factors [f(RH)] and 20

percent best days coefficients are provided in Appendix A, and are based on data from 

FLAG 2010.

 POSTUTIL was used to combine units from sources with multiple units and to perform 

HNO3/NO3 repartitioning. However, each source was processed separately by 

POSTUTIL for each model scenario and meteorological year. 

 Each source was processed separately by CALPOST for each model scenario and 

meteorological year.

 The 98th percentile value was reported to three decimal places because of the level of 

precision reported by CALPOST.

5.3.1 POSTUTIL

As explained further in the final notice for this action, the ammonia-limiting correction in the 

POSTUTIL postprocessor was used in all the model simulations to repartition the CALPUFFpredicted nitrate concentrations. This correction in POSTUTIL repartitions the particulate nitrate 

and gaseous nitric acid concentrations based on nitrate and sulfate concentrations from all of the 

units modeled at a given receptor, the available background ammonia, and gridded temperature 

and humidity data. The CALPUFF model simulates individual units (or sources) that may have 

multiple parcels of air originating at each of the units. CALPUFF also assumes that the 

background ammonia concentration is fully available to react with emissions from each unit, 

regardless of the number of units or overlapping air parcels. However, in reality, the total 

emissions from the combined units compete for the available ammonia and there is a possibility 

that different air parcels can overlap at a Class I area. The ammonia-limiting correction in 

POSTUTIL is designed to repartition the available ammonia to react with emissions from all of 

 

44 National Park Service website with Class I area receptor information. 

http://www2.nature.nps.gov/air/Maps/Receptors/index.cfm. This data is in the docket and can be made available 

upon request.
15

the units and overlapping air parcels, thereby avoiding double counting of the background 

ammonia. EPA Region 8 used the same approach in the modeling for Montana BART sources.45

This approach is a standard configuration in the CALPUFF modeling system.

To apply the ammonia-limiting correction in POSTUTIL, the MNITRATE=1 setting was used, 

the CALPUFF data were not scaled to alter the emission rate of all units modeled, and the 

associated background ammonia concentrations outlined in Table 7 were applied to each source.

To correct for ammonia-limiting conditions in the baseline scenarios, all units from a single 

source were combined with the use of POSTUTIL and the MNITRATE setting. For example, the 

baseline CALPUFF data files for the three units of the Laramie River Power Plant were 

combined in POSTUTIL, and used the MNITRATE=1 setting and the constant 1.0 ppb 

background ammonia concentration. For the control scenarios, the CALPUFF data file from the 

unit of interest was combined with the baseline CALPUFF data files of the remaining units by 

POSTUTIL, along with the MNITRATE=1 setting and the associated background ammonia 

concentration. For example, the control CALPUFF data file for unit 1 of the Laramie River 

Power Plant was combined with the baseline CALPUFF data file for unit 2 and unit 3. This 

approach was used to correct for ammonia-limiting conditions and isolate the degree of visibility 

improvement from the control technology. Details of the parameter settings in POSTUTIL are 

provided in Appendix G.

5.3.2 CALPOST

The CALPOST postprocessor was used to calculate the visibility impacts from the individual 

sources at a given receptor for each meteorological year modeled. The visibility impacts were

determined by comparing the impacts of sulfate, nitrate, nitrogen dioxide, course particulate 

matter (PM10), and fine particulate matter (PM2.5) from the sources to the 20 percent best days 

natural background conditions at each Class I area (i.e., delta-deciview [Δdv]). The Δdv

calculations followed the FLAG 2010 guidance. In particular, Method 8 was used to assess the 

visibility impacts of the individual BART sources. Method 8 uses an improved algorithm to 

estimate the light scattering and visibility impairment caused by air pollutants. To ensure 

compliance with the FLAG 2010 guidance, the CALPOST setting MVISCHECK was set to 1. 

All settings that comply with MVISCHECK, include:

 MVISBK = 8 to invoke the latest FLAG guidance (latest IMPROVE equation); and

 M8_MODE = 5 to use species specific relative humidity factors.

The species concentrations of the 20 percent best days natural background conditions at each 

Class I area are defined in Appendix A, Table A-1. The species-specific relative humidity

adjustment factors for each Class I area are defined in Appendix A, Table A-2 to Table A-5.

6.0 PRESENTATION OF RESULTS AND REPORTING

The change in visibility impairment (i.e., delta-deciview [Δdv]) for the visibility modeling is 

based on the increase in the haze index from a source relative to natural background, defined as 

the 20 percent best natural visibility days for each Class I area.

 

45 Modeling Protocol: Montana Regional Haze Federal Implementation Plan (FIP) Support, prepared for EPA 

Region 8 by Alpine Geophysics, LLC, November 21, 2011.
16

EPA has recognized that the CALPUFF model can be conservative in estimating visibility 

impairment, and therefore, consistent with the BART Guidelines, used the 98th percentile model 

results instead of the maximum modeled visibility impairment to address the possibility of model 

over predictions.46 The FLAG 2010 guidance also recognizes that the visibility impairment is 

based on the 98th Δdv percentile value (or 8th highest value).

Output from CALPOST was configured to provide a ranked list of the Δdv values in each Class I 

area. The 98th percentile Δdv value was then determined directly from the CALPOST output.

The impacts (or 98th percentile Δdv value) were calculated separately for each meteorological 

year for each source impact on the Class I areas.

If the simulation is a control simulation for a specific source, the 98th percentile Δdv

improvement (or visibility improvement) was also determined separately for each meteorological 

year and Class I area. The 98th percentile Δdv improvement is defined as the difference in 98th

Δdv of the baseline and the 98th percentile Δdv of the control case.

The visibility impacts for all modeled scenarios are reported in Appendix H. This includes the 

impacts for each unit of individual sources at all modeled Class I areas and meteorological years. 

 

46 40 CFR 51 Appendix Y.IV.D. and 70 FR 39121.
17

APPENDIX A – BACKGROUND CONDITIONS ASSUMED FOR MODELING

Table A-1. 20 Percent Best Natural Background Conditions by Aerosol Component and 

Class I Area [μg/m3]

Class I Area Ammonium 

Sulfate

Ammonium 

Nitrate

Organic 

Carbon

Elemental 

Carbon SOIL Coarse Matter Sea Salt

Badlands 0.05 0.05 0.23 0.01 0.22 0.99 0.00

Bridger 0.05 0.04 0.14 0.01 0.07 0.33 0.00

Fitzpatrick 0.05 0.04 0.14 0.01 0.07 0.33 0.00

Grand Teton 0.06 0.05 0.17 0.01 0.08 0.33 0.00

Mt. Zirkel 0.06 0.04 0.16 0.01 0.09 0.60 0.00

North Absaroka 0.05 0.04 0.16 0.00 0.11 0.82 0.00

Rawah 0.06 0.04 0.16 0.01 0.09 0.60 0.00

Rocky Mountain 0.04 0.02 0.15 0.01 0.09 0.68 0.00

Teton 0.06 0.05 0.17 0.01 0.08 0.33 0.00

Washakie 0.05 0.04 0.16 0.00 0.11 0.82 0.00

Wind Cave 0.05 0.04 0.20 0.01 0.19 1.05 0.00

Yellowstone 0.06 0.05 0.17 0.01 0.08 0.33 0.00

Values gathered from Table 5 of the Federal Land Managers’ Air Quality Related Values Workgroup 

(FLAG) 2008. Phase I Report—Revised (2010).

Table A-2. Monthly fL(RH) – Large (NH4)2SO4 and NH4NO3 Relative Humidity 

Adjustment Factors by Month and Class I Area

Class I Area Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Badlands 2.31 2.31 2.31 2.21 2.34 2.25 2.08 2.05 2.02 2.05 2.38 2.33

Bridger 2.22 2.10 2.04 1.95 1.95 1.67 1.46 1.44 1.68 1.83 2.19 2.16

Fitzpatrick 2.22 2.10 2.04 1.95 1.94 1.68 1.47 1.44 1.68 1.83 2.18 2.16

Grand Teton 2.27 2.14 2.01 1.91 1.90 1.68 1.48 1.44 1.64 1.84 2.16 2.24

Mt. Zirkel 2.00 1.99 1.89 1.92 1.98 1.72 1.63 1.70 1.81 1.75 1.97 1.95

North Absaroka 2.16 2.05 2.01 1.95 1.94 1.77 1.58 1.50 1.67 1.87 2.12 2.14

Rawah 1.91 1.96 1.89 1.96 2.04 1.79 1.71 1.78 1.86 1.75 1.94 1.90

Rocky Mountain 1.77 1.85 1.84 1.95 2.04 1.80 1.73 1.77 1.84 1.70 1.84 1.76

Teton 2.22 2.09 2.01 1.92 1.91 1.72 1.52 1.47 1.65 1.86 2.15 2.19

Washakie 2.16 2.05 2.01 1.94 1.93 1.74 1.54 1.48 1.66 1.86 2.12 2.14

Wind Cave 2.23 2.22 2.22 2.18 2.32 2.18 2.00 1.97 1.95 2.00 2.30 2.24

Yellowstone 2.24 2.11 2.03 1.95 1.94 1.78 1.59 1.53 1.69 1.91 2.19 2.22

Values gathered from Table 7 of the Federal Land Managers’ Air Quality Related Values Workgroup 

(FLAG) 2008. Phase I Report—Revised (2010).

Table A-3. Monthly fS(RH) – Small (NH4)2SO4 and NH4NO3 Relative Humidity Adjustment 

Factors by Month and Class I Area

Class I Area Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Badlands 2.94 2.96 3.01 2.87 3.10 2.91 2.64 2.59 2.56 2.58 3.11 2.98

Bridger 2.78 2.60 2.55 2.43 2.45 1.99 1.65 1.63 2.03 2.25 2.78 2.68

Fitzpatrick 2.78 2.60 2.54 2.43 2.44 1.99 1.66 1.63 2.02 2.25 2.77 2.68

Grand Teton 2.88 2.66 2.48 2.35 2.34 2.00 1.68 1.62 1.94 2.25 2.73 2.82

Mt. Zirkel 2.43 2.44 2.31 2.37 2.51 2.07 1.92 2.02 2.23 2.12 2.41 2.37

North Absaroka 2.68 2.51 2.50 2.42 2.40 2.13 1.83 1.72 1.98 2.31 2.65 2.65

Rawah 2.31 2.39 2.32 2.44 2.61 2.19 2.05 2.16 2.31 2.12 2.37 2.29

Rocky Mountain 2.09 2.24 2.24 2.45 2.62 2.22 2.09 2.15 2.29 2.04 2.23 2.08

Teton 2.78 2.59 2.49 2.37 2.36 2.06 1.75 1.67 1.96 2.28 2.70 2.73

Washakie 2.68 2.52 2.49 2.40 2.40 2.09 1.77 1.68 1.98 2.29 2.66 2.65

Wind Cave 2.81 2.81 2.86 2.82 3.06 2.81 2.50 2.46 2.44 2.52 2.97 2.83

Yellowstone 2.82 2.61 2.53 2.42 2.41 2.16 1.86 1.76 2.02 2.36 2.78 2.80
18

Values gathered from Table 8 of the Federal Land Managers’ Air Quality Related Values Workgroup 

(FLAG) 2008. Phase I Report—Revised (2010).

Table A-4. Monthly fSS(RH) – Sea Salt Relative Humidity Adjustment Factors by Month 

and Class I Area

Class I Area Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Badlands 3.37 3.33 3.27 3.05 3.25 3.15 2.89 2.81 2.74 2.82 3.41 3.38

Bridger 3.25 3.05 2.90 2.67 2.62 2.17 1.81 1.79 2.17 2.43 3.15 3.17

Fitzpatrick 3.25 3.05 2.88 2.66 2.62 2.18 1.82 1.79 2.16 2.43 3.13 3.18

Grand Teton 3.34 3.10 2.82 2.59 2.56 2.21 1.85 1.78 2.12 2.48 3.10 3.29

Mt. Zirkel 2.85 2.83 2.61 2.61 2.67 2.24 2.10 2.23 2.38 2.31 2.75 2.78

North Absaroka 3.18 2.97 2.83 2.66 2.64 2.35 2.02 1.89 2.16 2.53 3.03 3.13

Rawah 2.70 2.74 2.58 2.65 2.76 2.36 2.23 2.37 2.45 2.31 2.69 2.66

Rocky Mountain 2.44 2.56 2.47 2.64 2.75 2.37 2.26 2.36 2.41 2.20 2.51 2.41

Teton 3.26 3.04 2.83 2.61 2.59 2.27 1.93 1.83 2.14 2.50 3.07 3.21

Washakie 3.18 2.98 2.83 2.64 2.62 2.31 1.96 1.85 2.15 2.50 3.04 3.14

Wind Cave 3.25 3.20 3.13 3.01 3.22 3.06 2.75 2.68 2.63 2.75 3.28 3.24

Yellowstone 3.29 3.05 2.87 2.66 2.65 2.39 2.05 1.93 2.21 2.59 3.14 3.25

Values gathered from Table 9 of the Federal Land Managers’ Air Quality Related Values Workgroup 

(FLAG) 2008. Phase I Report—Revised (2010).

Table A-5. Monthly Site-Specific f(RH) Values for Class I Areas Based on IMPROVE Site 

Location

Class I Area Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Badlands 2.8 2.8 2.8 2.6 2.8 2.7 2.4 2.4 2.3 2.3 2.9 2.8

Bridger 2.5 2.3 2.3 2.1 2.1 1.8 1.5 1.5 1.8 2.0 2.5 2.4

Fitzpatrick 2.5 2.3 2.3 2.1 2.1 1.8 1.5 1.5 1.8 2.0 2.5 2.4

Grand Teton 2.5 2.3 2.2 2.1 2.1 1.9 1.7 1.6 1.8 2.1 2.4 2.5

Mt. Zirkel 2.2 2.2 2.0 2.1 2.2 1.8 1.7 1.8 2.0 1.9 2.1 2.1

North Absaroka 2.4 2.2 2.2 2.1 2.1 1.9 1.6 1.5 1.8 2.0 2.3 2.4

Rawah 2.2 2.2 2.0 2.1 2.2 1.8 1.7 1.8 2.0 1.9 2.1 2.1

Rocky Mountain 1.9 2.0 2.0 2.1 2.3 2.0 1.9 1.9 2.0 1.8 2.0 1.9

Teton 2.5 2.3 2.2 2.1 2.1 1.9 1.7 1.6 1.8 2.1 2.4 2.5

Washakie 2.4 2.2 2.2 2.1 2.1 1.9 1.6 1.5 1.8 2.0 2.3 2.4

Wind Cave 2.5 2.5 2.5 2.5 2.6 2.5 2.2 2.2 2.1 2.2 2.6 2.5

Yellowstone 2.5 2.3 2.2 2.1 2.1 1.9 1.7 1.6 1.8 2.1 2.4 2.5

Values gathered from Table A-2 of the Guidance for Estimating Natural Visibility Conditions Under the 

Regional Haze Rule, Office of Air Quality Planning and Standards, Emissions, Monitoring and Analysis 

Division, Air Quality Trends Analysis Group, EPA-454/B-03-005, September 2003.
19

APPENDIX B – EMISSION ASSUMPTIONS FOR MODELING

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

CALPUFF Inputs 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

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 B.2 – Modeling Assumptions for Basin Electric – Laramie River Station Unit 2

CALPUFF Inputs 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 B.3 – Modeling Assumptions for Basin Electric – Laramie River Station Unit 3

CALPUFF Inputs 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
20

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 

(meters/second) 22.25 22.25 22.25 22.25

Exit Temperature 

(Kelvin) 352.0 352.0 352.0 352.0

Table B.4 – Modeling Assumptions for PacifiCorp - Dave Johnston Unit 1

CALPUFF Inputs 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 B.5 – Modeling Assumptions for PacifiCorp - Dave Johnston Unit 2

CALPUFF Inputs 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 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) 28.69 28.69 28.69 28.69

Exit Temperature 

(Kelvin) 425.93 425.93 425.93 425.93

Table B.6 – Modeling Assumptions for PacifiCorp - Dave Johnston Unit 3

CALPUFF Inputs Baseline Scenario 1 Scenario 2 Scenario 3
21

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 B.7 – Modeling Assumptions for PacifiCorp - Dave Johnston Unit 4

CALPUFF Inputs 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

Table B.8 – Modeling Assumptions for PacifiCorp – Jim Bridger Unit 1

CALPUFF Inputs Baseline Scenario 1 Scenario 2 Scenario 3

SO2 (lb/hr) 900 900 900 900

Total Sulfate (SO4)(lb/hr) 54.1 54.1 54.1 54.1

NOx (lb/hr) 2788.1 1279.8 1023.9 355.5

HNO3 0 0 0 0

NO3 0 0 0 0

PM10-2.5

(coarse PM)(lb/hr) 77.4 77.4 77.4 77.4

PM2.5 (lb/hr) 102.6 102.6 102.6 102.6

Stack Height (meters) 152 152 152 152

Base Elevation (meters) 2036 2036 2036 2036
22

Stack Diameter (meters) 7.32 7.32 7.32 7.32

Exit Velocity 

(meters/second) 24.7 24.7 24.7 24.7

Exit Temperature 

(Kelvin) 328 328 328 328

Table B.9 – Modeling Assumptions for PacifiCorp - Jim Bridger Unit 2

CALPUFF Inputs Baseline Scenario 1 Scenario 2 Scenario 3

SO2 (lb/hr) 900 900 900 900

Total Sulfate (SO4)(lb/hr) 54.1 54.1 54.1 54.1

NOx (lb/hr) 2772.3 1386.5 1109.2 374.1

HNO3 0 0 0 0

NO3 0 0 0 0

PM10-2.5

(coarse PM)(lb/hr) 77.4 77.4 77.4 77.4

PM2.5 (lb/hr) 102.6 102.6 102.6 102.6

Stack Height (meters) 152 152 152 152

Base Elevation (meters) 2036 2036 2036 2036

Stack Diameter (meters) 7.32 7.32 7.32 7.32

Exit Velocity 

(meters/second) 24.7 24.7 24.7 24.7

Exit Temperature 

(Kelvin) 328 328 328 328

Table B.10 – Modeling Assumptions for PacifiCorp - Jim Bridger Unit 3

CALPUFF Inputs Baseline Scenario 1 Scenario 2 Scenario 3

SO2 (lb/hr) 900 900 900 900

Total Sulfate (SO4)(lb/hr) 54.1 54.1 54.1 54.1

NOx (lb/hr) 2670.0 1408.5 1126.8 358.4

HNO3 0 0 0 0

NO3 0 0 0 0

PM10-2.5

(coarse PM)(lb/hr) 77.4 77.4 77.4 77.4

PM2.5 (lb/hr) 102.6 102.6 102.6 102.6

Stack Height (meters) 152 152 152 152

Base Elevation (meters) 2036 2036 2036 2036

Stack Diameter (meters) 7.32 7.32 7.32 7.32

Exit Velocity 

(meters/second) 24.7 24.7 24.7 24.7

Exit Temperature 

(Kelvin) 328 328 328 328

Table B.11 – Modeling Assumptions for PacifiCorp - Jim Bridger Unit 4

CALPUFF Inputs Baseline Scenario 1 Scenario 2 Scenario 3

SO2 (lb/hr) 900 900 900 900

Total Sulfate (SO4)(lb/hr) 54.1 54.1 54.1 54.1

NOx (lb/hr) 2968.9 1449.9 1159.9 374.5
23

HNO3 0 0 0 0

NO3 0 0 0 0

PM10-2.5

(coarse PM)(lb/hr) 77.4 77.4 77.4 77.4

PM2.5 (lb/hr) 102.6 102.6 102.6 102.6

Stack Height (meters) 152 152 152 152

Base Elevation (meters) 2036 2036 2036 2036

Stack Diameter (meters) 7.32 7.32 7.32 7.32

Exit Velocity 

(meters/second) 24.7 24.7 24.7 24.7

Exit Temperature 

(Kelvin) 328 328 328 328

Table B.12 – Modeling Assumptions for PacifiCorp - Naughton Unit 1

CALPUFF Inputs 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 B.13 – Modeling Assumptions for PacifiCorp - Naughton Unit 2

CALPUFF Inputs 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
24

Exit Temperature 

(Kelvin) 323 323 323 323

Table B.14 – Modeling Assumptions for PacifiCorp - Naughton Unit 3

CALPUFF Inputs 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

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 B.15 – Modeling Assumptions for PacifiCorp – Wyodak

CALPUFF Inputs 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
25

APPENDIX C – CALMET CONTROL FILE INPUTS

Variable Description Value

INPUT GROUP 1

IBYR Year 2001, 2002, 2003

IBTZ Base Time Zone 7

IRTYPE Run Type 1

LCALGRD Compute Data Fields for CALGRD T

INPUT GROUP 2

PMAP Map Projection LCC (Lambert Conformal Conic)

DGRIDKM Grid Spacing (km) 4

NZ Number of Layers 10

ZFACE Cell Face Heights (m) 0, 20, 40, 100, 140, 320, 580, 

1020, 1480, 2220, 3500

INPUT GROUP 4

NOOBS No Observation Mode 0

INPUT GROUP 5

IWFCOD Model selection variable 1

IFRADJ Froude number adjustment 1

IKINE Kinematic effects 0

IOBR Use O’Brien procedure 0

ISLOPE Slope flow effects 1

IEXTRP Extrapolate surface wind observations -4

ICALM Extrapolate calm surface winds 0

BIAS Biases for weights of surface and upper air stations All 0

RMIN2 Minimum Distance for Extrapolation -1

IPROG Use Gridded Prognostic Model Output 14 (MM5 Data)

ISTEPPG Time Step (hours) 1

LVARY Use varying radius of influence F

RMAX 1 Maximum Radius of Influence (surface layer, km) 30

RMAX 2 Maximum Radius of Influence (layers aloft, km) 50

RMIN Minimum radius of influence (km) 0.1

TERRAD Radius of Influence for Terrain (km) 15

R1 Relative Weighting of First Guess Wind Field and 

Observations (km) 5

R2 Relative Weighting Aloft (km) 25

IDIOPT 1 Surface temperature 0

IDIOPT 2 Upper air lapse rate 0

ZUPT Lapse rate depth (m) 200

IDIOPT 3 Average wind components 0

IUPWND Upper air station -1

ZUPWND (1)

ZUPWND (2) Bottom and top of layer for domain scale winds (m) 1, 1000 1, 1000

IDIOPT4 Surface wind components 0

IDIOPT5 Upper air wind components 0

INPUT GROUP 6

IAVEZI Spatial averaging 1

MNMDAV Max search radius 1

HAFANG Half angle for averaging (deg) 30

ILEVZI Layer of winds in averaging 1

ZIMAX Maximum overland mixing height (m) 3500

ITPROG 3D temperature source 1

IRAD Interpolation type 1

TRADKM Radius of influence – temperature (km) 500

NUMTS Maximum number of Stations 5

IAVET Spatial averaging of temperatures 1

NFLAGP Precipitation interpolation 2
26

APPENDIX D – CALPUFF CONTROL FILE INPUTS

Variable Description Value 

INPUT GROUP 1

METRUN Control parameter for running all 

periods in met file 0

IBYR Starting year 2001, 2002, 2003 

XBTZ Base time zone 7 

NSPEC Number of chemical species modeled 7 

NSE Number of species emitted 5 (or 4) 

METFM Meteorological data format 1 

INPUT GROUP 2

MGAUSS Vertical distribution in near field 1 

MCTADJ Terrain adjustment method 3 

MCTSG Subgrid scale complex terrain 0 

MSLUG Elongated puffs 0 

MTRANS Transitional plume rise 1 

MTIP Stack tip downwash 1 

MSHEAR Vertical wind shear 0 

MSPLIT Puff splitting allowed? 0 

MCHEM Chemical mechanism 1 

MAQCHEM Aqueous phase transformation 0 

MWET Wet removal 1 

MDRY Dry deposition 1 

MTILT Gravitational Settling 0

MDISP Dispersion Coefficients 3 

MROUGH Adjust sigma for roughness 0 

MPARTL Partial plume penetration of inversions 1 

MTINV Strength of Temperature Inversion 0

MPDF PDF for convective conditions 0 

MSGTIBL Sub-Grid module used for shore line 0

MBCON Boundary Conditions Modeled 0

INPUT GROUP 4

PMAP Map projection LCC 

DGRIDKM Grid spacing 4 

ZFACE Cell face heights (m) 0, 20, 40, 100, 140, 320, 580, 1020, 1480, 

2220, 3500

INPUT GROUP 6

NHILL Number of terrain features 0 

INPUT GROUP 7

Dry Gas Deposition Chemical parameters for dry gas 

deposition Defaults 

INPUT GROUP 8

Dry Particle Deposition Size parameters for dry particle 

deposition SO4, NO3, PM2.5, PM10

Geometric Mass Mean Diameter [μm]

0.48 [PM10 = 6.50]

Geometric Standard Deviation [μm]

2.00 [PM10=1.00]

INPUT GROUP 11

MOZ Ozone Input option 1 

BCK03 Background ozone – all months (ppb) 44.0 

BCKNH3 Background ammonia (ppb) See Table 7

INPUT GROUP 12

XMAXZI Maximum mixing height (m) 3500 

XMINZI Minimum mixing height (m) 50 
27

APPENDIX E – CLASS I RECEPTOR DOMAINS

Table E.1 – Badlands National Park Receptors for Modeling

Table E.2 – Bridger Wilderness Area Receptors for Modeling
28

Table E.3 – Fitzpatrick Wilderness Area Receptors for Modeling

Table E.4 – Grand Teton National Park Receptors for Modeling
29

Table E.5 – Mt. Zirkel Wilderness Area Receptors for Modeling

Table E.6 – North Absaroka Wilderness Area Receptors for Modeling
30

Table E.7 – Rawah Wilderness Area Receptors for Modeling

Table E.8 – Rocky Mountain National Park Receptors for Modeling
31

Table E.9 – Teton Wilderness Area Receptors for Modeling

Table E.10 – Washakie Wilderness Area Receptors for Modeling
32

Table E.11 – Wind Cave National Park Receptors for Modeling

Table E.12 – Yellowstone National Park Receptors for Modeling
33

APPENDIX F – CALPOST CONTROL FILE INPUTS

Variable Description Value 

INPUT GROUP 1

ASPEC Species to Process VISIB 

ILAYER Layer/deposition code 1 

A,B Scaling factors 0,0 

LBACK Add background concentrations? F 

BTZONE Base time zone 7 

INPUT GROUP 2

MVISCHECK Test Visibility Options for Conformity to FLAG 2008 T

RHMAX Maximum Relative Humidity 95

LVSO4 Sulfate included in extinction T 

LVNO3 Nitrate included in extinction T 

LVOC Organic Carbon included in extinction F 

LVPMC Coarse Particles included in extinction T 

LVPMF Fine Particles included in extinction T 

LVEC Elemental Carbon included in extinction F 

LVNO2 NO2 Absorption T

LVBK Include background? T 

EEPMC Extinction efficiencies for Coarse PM 0.6 

EEPMF Extinction efficiencies for Fine PM 1.0 

EEPMCBK Extinction efficiencies for Background Coarse PM 0.6 

EESO4 Extinction efficiencies for Ammonium Sulfate 3.0 

EENO3 Extinction efficiencies for Ammonium Nitrate 3.0 

EEOC Extinction efficiencies for Organic Carbon 4.0 

EESOIL Extinction efficiencies for Soil 1.0 

EEEC Extinction efficiencies for Elemental Carbon 10.0 

EENO2 Extinction efficiencies for NO2 Gas 0.1755

MVISBK Visibility calculation method 8

RHFAC Monthly RH adjustment factors Table A-5

BKSO4 Background concentrations for SO4 Table A-1

BKNO3 Background concentrations for NO3 Table A-1

BKPMC Background concentrations for Coarse PM Table A-1

BK OC Background concentrations for Organic Carbon Table A-1

BKSOIL Background concentrations for Soil Table A-1

BKEC Background concentrations for Elemental Carbon Table A-1

M8_Mode Relative Humidity Adjustment Factors 5

BKSALT Background concentrations for Sea Salt Table A-1

RHFSML Relative Humidity Adjustment Factors for Small Table A-3

RHFLG Relative Humidity Adjustment Factors for Large Table A-2

RHFSEA Relative Humidity Adjustment Factors for Sea Salt Table A-4

BEXTRAY Extinction due to Rayleigh scattering 10.0 
34

APPENDIX G – POSTUTIL CONTROL FILE INPUTS

Variable Description Value 

INPUT GROUP 1 

NSPECINP Number of species to process from CALPUFF runs 7

NSPECOUT Number of species to write to output file 7

NSCALED Number of CALPUFF data files that will be scaled 0

MNITRATE Recompute the HNO3/NO3 partition for concentrations? 1

NH3TYP What is the input source of Ammonia? 3

BCKNH3 Background ammonia concentration (ppb) used for HNO3/NO3 partition See Table 7
35

APPENDIX H – VISIBILITY IMPACT RESULTS

To address the comments on the modeling performed for the June 2013 revised proposal, EPA 

Region 8 adopted a new modeling protocol that made several improvements to the CALPUFF 

visibility modeling. With the exception of CALMET, EPA Region 8 used the approved,

regulatory version of the CALPUFF modeling system that was available at the time the updated 

modeling was being completed. EPA Region 8 continued to use the meteorological data for the 

years 2001 to 2003 that had been provided by the State of Wyoming using the 2005 approved, 

regulatory version of the CALMET model. EPA Region 8 continued to rely on the CALMET 

data provided by the State because there is no evidence that the updates incorporated into the 

current, approved regulatory version of CALMET (version 5.8) would have substantially 

affected the model results. Using the meteorological data generated by the 2005 version of the 

CALMET model is also consistent with the previous modeling performed by WRAP and several 

states and EPA regions.

The updated modeling also used the latest visibility calculations and assumptions specified in the 

FLAG 2010 guidance47 (Method 8) to assess the visibility impacts of individual BART sources.

Method 8 uses an improved algorithm to estimate the light scattering and visibility impairment 

caused by air pollutants. EPA Region 8 also decided to assume lower background ammonia 

concentrations and use the ammonia-limiting correction (using the MNITRATE=1 option in 

POSTUTIL) for BART power plant sources with multiple units. Additional details of the EPA 

Region 8 decisions related to the modeling are discussed in the main report above and in the final 

Federal Register notice for this action. 

This appendix includes the visibility results from the updated modeling based on the new

modeling approach discussed in the main body of this report. A separate table for each BART 

source is included below. For the PacifiCorp Naughton and Jim Bridger power plants, two tables 

are included to present the model results using background ammonia concentrations based on 

guidance and using background ammonia concentrations based on monitoring data. Each table 

includes the 98th percentile and visibility improvement for each model scenario by unit, Class I 

area, and model year.

 

47 Federal Land Managers’ Air Quality Related Values Workgroup (FLAG) 2008. Phase I Report—Revised (2010).
36

Table H.1 – Model Results for Basin Electric – Laramie River Station Units

Unit Class I Area by Year

Baseline

Scenario 1 Scenario 2 Scenario 3

LNB/OFA LNB/OFA/SNCR LNB/OFA/SCR

98th Percentile 

[Δdv]

98th

Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

Unit 1

Badlands 2001 2.774 2.614 0.160 2.521 0.253 2.266 0.508

Badlands 2002 1.770 1.662 0.108 1.589 0.181 1.391 0.379

Badlands 2003 2.510 2.333 0.177 2.228 0.282 1.941 0.569

Wind Cave 2001 2.300 2.157 0.143 2.078 0.222 1.860 0.440

Wind Cave 2002 2.497 2.347 0.150 2.260 0.237 2.030 0.467

Wind Cave 2003 1.833 1.721 0.112 1.657 0.176 1.465 0.368

Rawah 2001 0.886 0.836 0.050 0.808 0.078 0.732 0.154

Rawah 2002 1.344 1.265 0.079 1.220 0.124 1.097 0.247

Rawah 2003 0.991 0.927 0.064 0.889 0.102 0.790 0.201

RMNP 2001 1.282 1.194 0.088 1.142 0.140 1.003 0.279

RMNP 2002 1.653 1.543 0.110 1.480 0.173 1.315 0.338

RMNP 2003 1.394 1.309 0.085 1.260 0.134 1.128 0.266

Unit 2

Badlands 2001 2.774 2.606 0.168 2.523 0.251 2.298 0.476

Badlands 2002 1.770 1.656 0.114 1.592 0.178 1.419 0.351

Badlands 2003 2.510 2.328 0.182 2.236 0.274 1.985 0.525

Wind Cave 2001 2.300 2.153 0.147 2.084 0.216 1.896 0.404

Wind Cave 2002 2.497 2.342 0.155 2.267 0.230 2.066 0.431

Wind Cave 2003 1.833 1.718 0.115 1.663 0.170 1.505 0.328

Rawah 2001 0.886 0.834 0.052 0.808 0.078 0.741 0.145

Rawah 2002 1.344 1.263 0.081 1.223 0.121 1.116 0.228

Rawah 2003 0.991 0.924 0.067 0.892 0.099 0.805 0.186

RMNP 2001 1.282 1.191 0.091 1.147 0.135 1.025 0.257

RMNP 2002 1.653 1.540 0.113 1.486 0.167 1.342 0.311

RMNP 2003 1.394 1.307 0.087 1.264 0.130 1.149 0.245
37

Unit Class I Area by Year

Baseline

Scenario 1 Scenario 2 Scenario 3

LNB/OFA LNB/OFA/SNCR LNB/OFA/SCR

98th Percentile 

[Δdv]

98th

Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

Unit 3

Badlands 2001 2.774 2.630 0.144 2.555 0.219 2.323 0.451

Badlands 2002 1.770 1.656 0.114 1.591 0.179 1.413 0.357

Badlands 2003 2.510 2.335 0.175 2.243 0.267 1.991 0.519

Wind Cave 2001 2.300 2.160 0.140 2.093 0.207 1.916 0.384

Wind Cave 2002 2.497 2.343 0.154 2.264 0.233 2.056 0.441

Wind Cave 2003 1.833 1.721 0.112 1.664 0.169 1.513 0.320

Rawah 2001 0.886 0.837 0.049 0.812 0.074 0.745 0.141

Rawah 2002 1.344 1.265 0.079 1.225 0.119 1.116 0.228

Rawah 2003 0.991 0.929 0.062 0.896 0.095 0.811 0.180

RMNP 2001 1.282 1.186 0.096 1.137 0.145 1.003 0.279

RMNP 2002 1.653 1.557 0.096 1.509 0.144 1.381 0.272

RMNP 2003 1.394 1.310 0.084 1.267 0.127 1.153 0.241

Table H.2 – Model Results for PacifiCorp – Dave Johnston Units

Unit Class I Area by Year

Baseline

Scenario 1 Scenario 2 Scenario 3

LNB/OFA LNB/OFA/SNCR LNB/OFA/SCR

98th Percentile 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

Unit 1

Badlands 2001 2.634 2.527 0.107 2.507 0.127 2.467 0.167

Badlands 2002 2.193 2.100 0.093 2.082 0.111 2.048 0.145

Badlands 2003 2.477 2.361 0.116 2.338 0.139 2.293 0.184

Wind Cave 2001 2.384 2.328 0.056 2.317 0.067 2.297 0.087

Wind Cave 2002 2.470 2.371 0.099 2.352 0.118 2.317 0.153

Wind Cave 2003 3.562 3.444 0.118 3.422 0.140 3.378 0.184

Mt Zirkel 2001 0.545 0.530 0.015 0.527 0.018 0.522 0.023
38

Unit Class I Area by Year

Baseline

Scenario 1 Scenario 2 Scenario 3

LNB/OFA LNB/OFA/SNCR LNB/OFA/SCR

98th Percentile 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

Mt Zirkel 2002 0.919 0.886 0.033 0.879 0.040 0.867 0.052

Mt Zirkel 2003 1.002 0.939 0.063 0.927 0.075 0.910 0.092

Rawah 2001 1.063 1.022 0.041 1.014 0.049 0.999 0.064

Rawah 2002 1.733 1.634 0.099 1.614 0.119 1.578 0.155

Rawah 2003 1.213 1.176 0.037 1.164 0.049 1.141 0.072

RMNP 2001 1.006 0.976 0.030 0.971 0.035 0.960 0.046

RMNP 2002 1.616 1.558 0.058 1.547 0.069 1.522 0.094

RMNP 2003 1.420 1.361 0.059 1.349 0.071 1.327 0.093

Unit 2

Badlands 2001 2.634 2.534 0.100 2.514 0.120 2.474 0.160

Badlands 2002 2.193 2.105 0.088 2.089 0.104 2.054 0.139

Badlands 2003 2.477 2.369 0.108 2.347 0.130 2.303 0.174

Wind Cave 2001 2.384 2.332 0.052 2.321 0.063 2.301 0.083

Wind Cave 2002 2.470 2.372 0.098 2.354 0.116 2.316 0.154

Wind Cave 2003 3.562 3.449 0.113 3.427 0.135 3.381 0.181

Mt Zirkel 2001 0.545 0.531 0.014 0.529 0.016 0.523 0.022

Mt Zirkel 2002 0.919 0.887 0.032 0.881 0.038 0.867 0.052

Mt Zirkel 2003 1.002 0.943 0.059 0.931 0.071 0.913 0.089

Rawah 2001 1.063 1.024 0.039 1.016 0.047 1.001 0.062

Rawah 2002 1.733 1.648 0.085 1.631 0.102 1.598 0.135

Rawah 2003 1.213 1.180 0.033 1.170 0.043 1.146 0.067

RMNP 2001 1.006 0.978 0.028 0.972 0.034 0.961 0.045

RMNP 2002 1.616 1.562 0.054 1.552 0.064 1.528 0.088

RMNP 2003 1.420 1.364 0.056 1.352 0.068 1.330 0.090

Unit 3

Badlands 2001 2.634 2.351 0.283 2.300 0.334 2.187 0.447

Badlands 2002 2.193 1.952 0.241 1.901 0.292 1.801 0.392

Badlands 2003 2.477 2.175 0.302 2.118 0.359 2.004 0.473
39

Unit Class I Area by Year

Baseline

Scenario 1 Scenario 2 Scenario 3

LNB/OFA LNB/OFA/SNCR LNB/OFA/SCR

98th Percentile 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

Wind Cave 2001 2.384 2.232 0.152 2.204 0.180 2.151 0.233

Wind Cave 2002 2.470 2.189 0.281 2.138 0.332 2.051 0.419

Wind Cave 2003 3.562 3.234 0.328 3.174 0.388 3.054 0.508

Mt Zirkel 2001 0.545 0.506 0.039 0.499 0.046 0.486 0.059

Mt Zirkel 2002 0.919 0.827 0.092 0.807 0.112 0.780 0.139

Mt Zirkel 2003 1.002 0.865 0.137 0.845 0.157 0.804 0.198

Rawah 2001 1.063 0.954 0.109 0.934 0.129 0.896 0.167

Rawah 2002 1.733 1.476 0.257 1.429 0.304 1.337 0.396

Rawah 2003 1.213 1.082 0.131 1.054 0.159 0.997 0.216

RMNP 2001 1.006 0.929 0.077 0.915 0.091 0.888 0.118

RMNP 2002 1.616 1.439 0.177 1.403 0.213 1.333 0.283

RMNP 2003 1.420 1.262 0.158 1.233 0.187 1.176 0.244

Unit 4

Badlands 2001 2.634 2.279 0.355 2.235 0.399 2.140 0.494

Badlands 2002 2.193 1.799 0.394 1.750 0.443 1.696 0.497

Badlands 2003 2.477 2.083 0.394 2.033 0.444 1.929 0.548

Wind Cave 2001 2.384 2.199 0.185 2.176 0.208 2.128 0.256

Wind Cave 2002 2.470 2.125 0.345 2.097 0.373 2.037 0.433

Wind Cave 2003 3.562 3.154 0.408 3.103 0.459 2.994 0.568

Mt Zirkel 2001 0.545 0.496 0.049 0.490 0.055 0.478 0.067

Mt Zirkel 2002 0.919 0.803 0.116 0.793 0.126 0.770 0.149

Mt Zirkel 2003 1.002 0.838 0.164 0.813 0.189 0.760 0.242

Rawah 2001 1.063 0.909 0.154 0.890 0.173 0.850 0.213

Rawah 2002 1.733 1.485 0.248 1.454 0.279 1.390 0.343

Rawah 2003 1.213 1.045 0.168 1.021 0.192 0.970 0.243

RMNP 2001 1.006 0.906 0.100 0.894 0.112 0.868 0.138

RMNP 2002 1.616 1.384 0.232 1.353 0.263 1.286 0.330
40

Unit Class I Area by Year

Baseline

Scenario 1 Scenario 2 Scenario 3

LNB/OFA LNB/OFA/SNCR LNB/OFA/SCR

98th Percentile 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

RMNP 2003 1.420 1.207 0.213 1.181 0.239 1.125 0.295

Table H.3 – Model Results for PacifiCorp – Jim Bridger Units with Background Ammonia Levels based on Boulder Monitor Data

Unit Class I Area by Year

Baseline

Scenario 1 Scenario 2 Scenario 3

LNB/OFA LNB/OFA/SNCR LNB/OFA/SCR

98th Percentile 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

Unit 1

Bridger 2001 1.854 1.750 0.104 1.719 0.135 1.634 0.220

Bridger 2002 2.570 2.438 0.132 2.424 0.146 2.387 0.183

Bridger 2003 1.759 1.590 0.169 1.562 0.197 1.490 0.269

Fitzpatrick 2001 1.179 1.072 0.107 1.053 0.126 1.005 0.174

Fitzpatrick 2002 1.581 1.420 0.161 1.393 0.188 1.326 0.255

Fitzpatrick 2003 0.943 0.861 0.082 0.847 0.096 0.813 0.130

Mt Zirkel 2001 2.246 2.069 0.177 2.053 0.193 1.987 0.259

Mt Zirkel 2002 2.544 2.394 0.150 2.366 0.178 2.289 0.255

Mt Zirkel 2003 2.005 1.860 0.145 1.831 0.174 1.781 0.224

Rawah 2001 1.585 1.487 0.098 1.480 0.105 1.459 0.126

Rawah 2002 2.396 2.168 0.228 2.127 0.269 2.016 0.380

Rawah 2003 1.869 1.724 0.145 1.698 0.171 1.626 0.243

RMNP 2001 1.442 1.318 0.124 1.296 0.146 1.240 0.202

RMNP 2002 2.255 2.096 0.159 2.068 0.187 1.983 0.272

RMNP 2003 1.963 1.849 0.114 1.827 0.136 1.767 0.196

Grand Teton 2001 0.840 0.767 0.073 0.755 0.085 0.722 0.118

Grand Teton 2002 1.165 1.066 0.099 1.049 0.116 1.006 0.159

Grand Teton 2003 0.786 0.736 0.050 0.730 0.056 0.712 0.074
41

Unit Class I Area by Year

Baseline

Scenario 1 Scenario 2 Scenario 3

LNB/OFA LNB/OFA/SNCR LNB/OFA/SCR

98th Percentile 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

Teton 2001 0.765 0.699 0.066 0.688 0.077 0.661 0.104

Teton 2002 0.911 0.822 0.089 0.807 0.104 0.768 0.143

Teton 2003 0.759 0.723 0.036 0.715 0.044 0.691 0.068

Washakie 2001 1.372 1.250 0.122 1.229 0.143 1.177 0.195

Washakie 2002 1.205 1.100 0.105 1.082 0.123 1.037 0.168

Washakie 2003 0.783 0.705 0.078 0.692 0.091 0.659 0.124

Yellowstone 2001 0.660 0.603 0.057 0.593 0.067 0.570 0.090

Yellowstone 2002 0.995 0.916 0.079 0.903 0.092 0.869 0.126

Yellowstone 2003 0.929 0.855 0.074 0.842 0.087 0.806 0.123

Unit 2

Bridger 2001 1.854 1.752 0.102 1.732 0.122 1.638 0.216

Bridger 2002 2.570 2.444 0.126 2.429 0.141 2.389 0.181

Bridger 2003 1.759 1.603 0.156 1.573 0.186 1.494 0.265

Fitzpatrick 2001 1.179 1.080 0.099 1.060 0.119 1.008 0.171

Fitzpatrick 2002 1.581 1.433 0.148 1.404 0.177 1.330 0.251

Fitzpatrick 2003 0.943 0.867 0.076 0.853 0.090 0.814 0.129

Mt Zirkel 2001 2.246 2.076 0.170 2.059 0.187 1.991 0.255

Mt Zirkel 2002 2.544 2.407 0.137 2.377 0.167 2.294 0.250

Mt Zirkel 2003 2.005 1.874 0.131 1.842 0.163 1.783 0.222

Rawah 2001 1.585 1.491 0.094 1.483 0.102 1.461 0.124

Rawah 2002 2.396 2.188 0.208 2.143 0.253 2.022 0.374

Rawah 2003 1.869 1.736 0.133 1.708 0.161 1.630 0.239

RMNP 2001 1.442 1.328 0.114 1.305 0.137 1.243 0.199

RMNP 2002 2.255 2.110 0.145 2.079 0.176 1.987 0.268

RMNP 2003 1.963 1.859 0.104 1.836 0.127 1.770 0.193

Grand Teton 2001 0.840 0.773 0.067 0.760 0.080 0.724 0.116

Grand Teton 2002 1.165 1.074 0.091 1.056 0.109 1.008 0.157
42

Unit Class I Area by Year

Baseline

Scenario 1 Scenario 2 Scenario 3

LNB/OFA LNB/OFA/SNCR LNB/OFA/SCR

98th Percentile 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

Grand Teton 2003 0.786 0.739 0.047 0.732 0.054 0.713 0.073

Teton 2001 0.765 0.704 0.061 0.692 0.073 0.662 0.103

Teton 2002 0.911 0.829 0.082 0.813 0.098 0.770 0.141

Teton 2003 0.759 0.727 0.032 0.718 0.041 0.692 0.067

Washakie 2001 1.372 1.260 0.112 1.238 0.134 1.180 0.192

Washakie 2002 1.205 1.108 0.097 1.089 0.116 1.040 0.165

Washakie 2003 0.783 0.712 0.071 0.697 0.086 0.661 0.122

Yellowstone 2001 0.660 0.607 0.053 0.597 0.063 0.571 0.089

Yellowstone 2002 0.995 0.922 0.073 0.908 0.087 0.870 0.125

Yellowstone 2003 0.929 0.862 0.067 0.847 0.082 0.808 0.121

Unit 3

Bridger 2001 1.854 1.754 0.100 1.747 0.107 1.650 0.204

Bridger 2002 2.570 2.451 0.119 2.436 0.134 2.394 0.176

Bridger 2003 1.759 1.618 0.141 1.587 0.172 1.504 0.255

Fitzpatrick 2001 1.179 1.089 0.090 1.069 0.110 1.014 0.165

Fitzpatrick 2002 1.581 1.446 0.135 1.417 0.164 1.339 0.242

Fitzpatrick 2003 0.943 0.874 0.069 0.859 0.084 0.819 0.124

Mt Zirkel 2001 2.246 2.089 0.157 2.067 0.179 2.002 0.244

Mt Zirkel 2002 2.544 2.420 0.124 2.390 0.154 2.304 0.240

Mt Zirkel 2003 2.005 1.889 0.116 1.857 0.148 1.791 0.214

Rawah 2001 1.585 1.494 0.091 1.486 0.099 1.464 0.121

Rawah 2002 2.396 2.208 0.188 2.163 0.233 2.036 0.360

Rawah 2003 1.869 1.749 0.120 1.720 0.149 1.640 0.229

RMNP 2001 1.442 1.338 0.104 1.315 0.127 1.251 0.191

RMNP 2002 2.255 2.124 0.131 2.093 0.162 2.000 0.255

RMNP 2003 1.963 1.869 0.094 1.846 0.117 1.778 0.185

Grand Teton 2001 0.840 0.779 0.061 0.766 0.074 0.730 0.110
43

Unit Class I Area by Year

Baseline

Scenario 1 Scenario 2 Scenario 3

LNB/OFA LNB/OFA/SNCR LNB/OFA/SCR

98th Percentile 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

Grand Teton 2002 1.165 1.082 0.083 1.064 0.101 1.014 0.151

Grand Teton 2003 0.786 0.741 0.045 0.735 0.051 0.715 0.071

Teton 2001 0.765 0.709 0.056 0.697 0.068 0.666 0.099

Teton 2002 0.911 0.837 0.074 0.820 0.091 0.775 0.136

Teton 2003 0.759 0.730 0.029 0.722 0.037 0.696 0.063

Washakie 2001 1.372 1.270 0.102 1.248 0.124 1.187 0.185

Washakie 2002 1.205 1.117 0.088 1.098 0.107 1.046 0.159

Washakie 2003 0.783 0.718 0.065 0.704 0.079 0.666 0.117

Yellowstone 2001 0.660 0.612 0.048 0.602 0.058 0.575 0.085

Yellowstone 2002 0.995 0.929 0.066 0.914 0.081 0.875 0.120

Yellowstone 2003 0.929 0.868 0.061 0.854 0.075 0.813 0.116

Unit 4

Bridger 2001 1.854 1.748 0.106 1.712 0.142 1.612 0.242

Bridger 2002 2.570 2.443 0.127 2.429 0.141 2.390 0.180

Bridger 2003 1.759 1.597 0.162 1.566 0.193 1.486 0.273

Fitzpatrick 2001 1.179 1.061 0.118 1.039 0.140 0.977 0.202

Fitzpatrick 2002 1.581 1.429 0.152 1.403 0.178 1.335 0.246

Fitzpatrick 2003 0.943 0.873 0.070 0.862 0.081 0.833 0.110

Mt Zirkel 2001 2.246 2.058 0.188 2.020 0.226 1.916 0.330

Mt Zirkel 2002 2.544 2.389 0.155 2.356 0.188 2.263 0.281

Mt Zirkel 2003 2.005 1.868 0.137 1.836 0.169 1.752 0.253

Rawah 2001 1.585 1.474 0.111 1.455 0.130 1.413 0.172

Rawah 2002 2.396 2.143 0.253 2.090 0.306 1.948 0.448

Rawah 2003 1.869 1.725 0.144 1.696 0.173 1.613 0.256

RMNP 2001 1.442 1.314 0.128 1.289 0.153 1.221 0.221

RMNP 2002 2.255 2.085 0.170 2.051 0.204 1.954 0.301

RMNP 2003 1.963 1.843 0.120 1.817 0.146 1.740 0.223
44

Unit Class I Area by Year

Baseline

Scenario 1 Scenario 2 Scenario 3

LNB/OFA LNB/OFA/SNCR LNB/OFA/SCR

98th Percentile 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

Grand Teton 2001 0.840 0.768 0.072 0.755 0.085 0.714 0.126

Grand Teton 2002 1.165 0.983 0.182 0.949 0.216 0.857 0.308

Grand Teton 2003 0.786 0.738 0.048 0.732 0.054 0.713 0.073

Teton 2001 0.765 0.701 0.064 0.690 0.075 0.659 0.106

Teton 2002 0.911 0.825 0.086 0.809 0.102 0.765 0.146

Teton 2003 0.759 0.727 0.032 0.720 0.039 0.695 0.064

Washakie 2001 1.372 1.195 0.177 1.161 0.211 1.071 0.301

Washakie 2002 1.205 1.101 0.104 1.081 0.124 1.029 0.176

Washakie 2003 0.783 0.714 0.069 0.702 0.081 0.670 0.113

Yellowstone 2001 0.660 0.605 0.055 0.596 0.064 0.569 0.091

Yellowstone 2002 0.995 0.910 0.085 0.894 0.101 0.852 0.143

Yellowstone 2003 0.929 0.848 0.081 0.832 0.097 0.786 0.143

Table H.4 – Model Results for PacifiCorp – Jim Bridger Units with Background Ammonia Levels based on IWAQM Recommendations

Unit Class I Area by Year

Baseline

Scenario 1 Scenario 2 Scenario 3

LNB/OFA LNB/OFA/SNCR LNB/OFA/SCR

98th Percentile 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

Unit 1

Bridger 2001 1.903 1.805 0.098 1.771 0.132 1.680 0.223

Bridger 2002 2.631 2.405 0.226 2.366 0.265 2.265 0.366

Bridger 2003 1.823 1.642 0.181 1.612 0.211 1.535 0.288

Fitzpatrick 2001 1.186 1.078 0.108 1.059 0.127 1.011 0.175

Fitzpatrick 2002 1.597 1.434 0.163 1.407 0.190 1.338 0.259

Fitzpatrick 2003 0.938 0.827 0.111 0.809 0.129 0.765 0.173

Mt Zirkel 2001 2.404 2.203 0.201 2.170 0.234 2.117 0.287
45

Unit Class I Area by Year

Baseline

Scenario 1 Scenario 2 Scenario 3

LNB/OFA LNB/OFA/SNCR LNB/OFA/SCR

98th Percentile 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

Mt Zirkel 2002 2.552 2.401 0.151 2.385 0.167 2.342 0.210

Mt Zirkel 2003 2.112 2.028 0.084 2.014 0.098 1.974 0.138

Rawah 2001 1.756 1.575 0.181 1.544 0.212 1.461 0.295

Rawah 2002 2.358 2.153 0.205 2.115 0.243 2.008 0.350

Rawah 2003 1.971 1.834 0.137 1.810 0.161 1.743 0.228

RMNP 2001 1.513 1.376 0.137 1.352 0.161 1.291 0.222

RMNP 2002 2.428 2.202 0.226 2.164 0.264 2.066 0.362

RMNP 2003 2.038 1.849 0.189 1.816 0.222 1.730 0.308

Grand Teton 2001 0.867 0.790 0.077 0.776 0.091 0.736 0.131

Grand Teton 2002 1.198 1.095 0.103 1.077 0.121 1.033 0.165

Grand Teton 2003 0.758 0.697 0.061 0.692 0.066 0.679 0.079

Teton 2001 0.752 0.688 0.064 0.677 0.075 0.649 0.103

Teton 2002 0.913 0.824 0.089 0.809 0.104 0.769 0.144

Teton 2003 0.737 0.691 0.046 0.685 0.052 0.667 0.070

Washakie 2001 1.399 1.279 0.120 1.260 0.139 1.212 0.187

Washakie 2002 1.211 1.105 0.106 1.087 0.124 1.042 0.169

Washakie 2003 0.795 0.715 0.080 0.702 0.093 0.669 0.126

Yellowstone 2001 0.662 0.605 0.057 0.595 0.067 0.572 0.090

Yellowstone 2002 0.976 0.900 0.076 0.887 0.089 0.854 0.122

Yellowstone 2003 1.000 0.913 0.087 0.898 0.102 0.855 0.145

Unit 2

Bridger 2001 1.903 1.822 0.081 1.785 0.118 1.685 0.218

Bridger 2002 2.631 2.423 0.208 2.381 0.250 2.270 0.361

Bridger 2003 1.823 1.656 0.167 1.623 0.200 1.539 0.284

Fitzpatrick 2001 1.186 1.086 0.100 1.066 0.120 1.013 0.173

Fitzpatrick 2002 1.597 1.447 0.150 1.417 0.180 1.342 0.255
46

Unit Class I Area by Year

Baseline

Scenario 1 Scenario 2 Scenario 3

LNB/OFA LNB/OFA/SNCR LNB/OFA/SCR

98th Percentile 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

Fitzpatrick 2003 0.938 0.836 0.102 0.816 0.122 0.767 0.171

Mt Zirkel 2001 2.404 2.221 0.183 2.181 0.223 2.120 0.284

Mt Zirkel 2002 2.552 2.409 0.143 2.391 0.161 2.344 0.208

Mt Zirkel 2003 2.112 2.035 0.077 2.019 0.093 1.976 0.136

Rawah 2001 1.756 1.591 0.165 1.556 0.200 1.465 0.291

Rawah 2002 2.358 2.171 0.187 2.131 0.227 2.013 0.345

Rawah 2003 1.971 1.846 0.125 1.819 0.152 1.747 0.224

RMNP 2001 1.513 1.387 0.126 1.362 0.151 1.294 0.219

RMNP 2002 2.428 2.220 0.208 2.179 0.249 2.071 0.357

RMNP 2003 2.038 1.865 0.173 1.829 0.209 1.734 0.304

Grand Teton 2001 0.867 0.796 0.071 0.782 0.085 0.738 0.129

Grand Teton 2002 1.198 1.103 0.095 1.084 0.114 1.035 0.163

Grand Teton 2003 0.758 0.702 0.056 0.694 0.064 0.680 0.078

Teton 2001 0.752 0.693 0.059 0.681 0.071 0.651 0.101

Teton 2002 0.913 0.831 0.082 0.815 0.098 0.771 0.142

Teton 2003 0.737 0.694 0.043 0.688 0.049 0.668 0.069

Washakie 2001 1.399 1.288 0.111 1.267 0.132 1.214 0.185

Washakie 2002 1.211 1.113 0.098 1.094 0.117 1.044 0.167

Washakie 2003 0.795 0.722 0.073 0.707 0.088 0.670 0.125

Yellowstone 2001 0.662 0.609 0.053 0.599 0.063 0.573 0.089

Yellowstone 2002 0.976 0.906 0.070 0.892 0.084 0.856 0.120

Yellowstone 2003 1.000 0.920 0.080 0.904 0.096 0.858 0.142

Unit 3

Bridger 2001 1.903 1.837 0.066 1.801 0.102 1.697 0.206

Bridger 2002 2.631 2.442 0.189 2.399 0.232 2.284 0.347

Bridger 2003 1.823 1.671 0.152 1.638 0.185 1.550 0.273
47

Unit Class I Area by Year

Baseline

Scenario 1 Scenario 2 Scenario 3

LNB/OFA LNB/OFA/SNCR LNB/OFA/SCR

98th Percentile 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

Fitzpatrick 2001 1.186 1.095 0.091 1.075 0.111 1.019 0.167

Fitzpatrick 2002 1.597 1.460 0.137 1.430 0.167 1.352 0.245

Fitzpatrick 2003 0.938 0.845 0.093 0.825 0.113 0.774 0.164

Mt Zirkel 2001 2.404 2.240 0.164 2.198 0.206 2.128 0.276

Mt Zirkel 2002 2.552 2.418 0.134 2.399 0.153 2.351 0.201

Mt Zirkel 2003 2.112 2.043 0.069 2.027 0.085 1.983 0.129

Rawah 2001 1.756 1.606 0.150 1.572 0.184 1.477 0.279

Rawah 2002 2.358 2.189 0.169 2.148 0.210 2.027 0.331

Rawah 2003 1.971 1.858 0.113 1.832 0.139 1.756 0.215

RMNP 2001 1.513 1.399 0.114 1.373 0.140 1.303 0.210

RMNP 2002 2.428 2.239 0.189 2.198 0.230 2.085 0.343

RMNP 2003 2.038 1.881 0.157 1.845 0.193 1.746 0.292

Grand Teton 2001 0.867 0.802 0.065 0.788 0.079 0.744 0.123

Grand Teton 2002 1.198 1.112 0.086 1.093 0.105 1.041 0.157

Grand Teton 2003 0.758 0.707 0.051 0.696 0.062 0.682 0.076

Teton 2001 0.752 0.698 0.054 0.686 0.066 0.655 0.097

Teton 2002 0.913 0.838 0.075 0.822 0.091 0.776 0.137

Teton 2003 0.737 0.696 0.041 0.690 0.047 0.671 0.066

Washakie 2001 1.399 1.299 0.100 1.277 0.122 1.222 0.177

Washakie 2002 1.211 1.122 0.089 1.103 0.108 1.050 0.161

Washakie 2003 0.795 0.729 0.066 0.714 0.081 0.675 0.120

Yellowstone 2001 0.662 0.614 0.048 0.604 0.058 0.577 0.085

Yellowstone 2002 0.976 0.912 0.064 0.898 0.078 0.860 0.116

Yellowstone 2003 1.000 0.928 0.072 0.911 0.089 0.864 0.136

Unit 4 Bridger 2001 1.903 1.804 0.099 1.765 0.138 1.658 0.245
48

Unit Class I Area by Year

Baseline

Scenario 1 Scenario 2 Scenario 3

LNB/OFA LNB/OFA/SNCR LNB/OFA/SCR

98th Percentile 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

Bridger 2002 2.631 2.411 0.220 2.368 0.263 2.254 0.377

Bridger 2003 1.823 1.649 0.174 1.616 0.207 1.530 0.293

Fitzpatrick 2001 1.186 1.067 0.119 1.045 0.141 0.992 0.194

Fitzpatrick 2002 1.597 1.406 0.191 1.382 0.215 1.316 0.281

Fitzpatrick 2003 0.938 0.877 0.061 0.866 0.072 0.837 0.101

Mt Zirkel 2001 2.404 2.210 0.194 2.192 0.212 2.134 0.270

Mt Zirkel 2002 2.552 2.419 0.133 2.404 0.148 2.365 0.187

Mt Zirkel 2003 2.112 2.019 0.093 2.001 0.111 1.934 0.178

Rawah 2001 1.756 1.599 0.157 1.568 0.188 1.483 0.273

Rawah 2002 2.358 2.130 0.228 2.080 0.278 1.940 0.418

Rawah 2003 1.971 1.826 0.145 1.797 0.174 1.708 0.263

RMNP 2001 1.513 1.371 0.142 1.344 0.169 1.270 0.243

RMNP 2002 2.428 2.204 0.224 2.162 0.266 2.049 0.379

RMNP 2003 2.038 1.852 0.186 1.816 0.222 1.717 0.321

Grand Teton 2001 0.867 0.791 0.076 0.771 0.096 0.712 0.155

Grand Teton 2002 1.198 1.008 0.190 0.972 0.226 0.877 0.321

Grand Teton 2003 0.758 0.698 0.060 0.694 0.064 0.679 0.079

Teton 2001 0.752 0.690 0.062 0.679 0.073 0.648 0.104

Teton 2002 0.913 0.827 0.086 0.810 0.103 0.766 0.147

Teton 2003 0.737 0.693 0.044 0.688 0.049 0.670 0.067

Washakie 2001 1.399 1.233 0.166 1.197 0.202 1.102 0.297

Washakie 2002 1.211 1.106 0.105 1.086 0.125 1.033 0.178

Washakie 2003 0.795 0.725 0.070 0.712 0.083 0.679 0.116

Yellowstone 2001 0.662 0.608 0.054 0.597 0.065 0.571 0.091

Yellowstone 2002 0.976 0.894 0.082 0.879 0.097 0.838 0.138
49

Unit Class I Area by Year

Baseline

Scenario 1 Scenario 2 Scenario 3

LNB/OFA LNB/OFA/SNCR LNB/OFA/SCR

98th Percentile 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

Yellowstone 2003 1.000 0.914 0.086 0.893 0.107 0.836 0.164

Table H.5 – Model Results for PacifiCorp – Naughton Units with Background Ammonia Levels based on Boulder Monitor Data

Unit Class I Area by Year

Baseline

Scenario 1 Scenario 2 Scenario 3

LNB/OFA LNB/OFA/SNCR LNB/OFA/SCR

98th Percentile 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

Unit 1

Bridger 2001 2.488 2.338 0.150 2.311 0.177 2.276 0.212

Bridger 2002 2.077 1.854 0.223 1.815 0.262 1.747 0.330

Bridger 2003 2.475 2.343 0.132 2.320 0.155 2.278 0.197

Fitzpatrick 2001 1.698 1.505 0.193 1.470 0.228 1.409 0.289

Fitzpatrick 2002 1.205 1.015 0.190 0.997 0.208 0.967 0.238

Fitzpatrick 2003 1.374 1.214 0.160 1.192 0.182 1.156 0.218

N. Absaroka 2001 0.779 0.683 0.096 0.667 0.112 0.640 0.139

N. Absaroka 2002 0.770 0.690 0.080 0.677 0.093 0.653 0.117

N. Absaroka 2003 0.490 0.439 0.051 0.430 0.060 0.421 0.069

Washakie 2001 1.216 1.113 0.103 1.095 0.121 1.067 0.149

Washakie 2002 1.062 0.960 0.102 0.942 0.120 0.912 0.150

Washakie 2003 0.656 0.599 0.057 0.590 0.066 0.573 0.083

Teton 2001 1.198 1.094 0.104 1.074 0.124 1.039 0.159

Teton 2002 1.021 0.917 0.104 0.902 0.119 0.882 0.139

Teton 2003 0.859 0.761 0.098 0.745 0.114 0.718 0.141

Grand Teton 2001 1.520 1.419 0.101 1.400 0.120 1.366 0.154

Grand Teton 2002 1.867 1.720 0.147 1.690 0.177 1.635 0.232

Grand Teton 2003 1.158 1.025 0.133 1.002 0.156 0.963 0.195
50

Unit Class I Area by Year

Baseline

Scenario 1 Scenario 2 Scenario 3

LNB/OFA LNB/OFA/SNCR LNB/OFA/SCR

98th Percentile 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

Yellowstone 2001 1.195 1.094 0.101 1.075 0.120 1.044 0.151

Yellowstone 2002 1.225 1.102 0.123 1.081 0.144 1.050 0.175

Yellowstone 2003 0.820 0.721 0.099 0.704 0.116 0.680 0.140

Unit 2

Bridger 2001 2.488 2.286 0.202 2.250 0.238 2.200 0.288

Bridger 2002 2.077 1.795 0.282 1.742 0.335 1.654 0.423

Bridger 2003 2.475 2.280 0.195 2.246 0.229 2.186 0.289

Fitzpatrick 2001 1.698 1.453 0.245 1.411 0.287 1.335 0.363

Fitzpatrick 2002 1.205 0.985 0.220 0.963 0.242 0.925 0.280

Fitzpatrick 2003 1.374 1.176 0.198 1.147 0.227 1.103 0.271

N. Absaroka 2001 0.779 0.660 0.119 0.640 0.139 0.607 0.172

N. Absaroka 2002 0.770 0.671 0.099 0.654 0.116 0.626 0.144

N. Absaroka 2003 0.490 0.426 0.064 0.418 0.072 0.408 0.082

Washakie 2001 1.216 1.065 0.151 1.041 0.175 1.000 0.216

Washakie 2002 1.062 0.931 0.131 0.908 0.154 0.870 0.192

Washakie 2003 0.656 0.561 0.095 0.550 0.106 0.532 0.124

Teton 2001 1.198 1.059 0.139 1.033 0.165 0.987 0.211

Teton 2002 1.021 0.894 0.127 0.875 0.146 0.851 0.170

Teton 2003 0.859 0.741 0.118 0.721 0.138 0.691 0.168

Grand Teton 2001 1.520 1.387 0.133 1.366 0.154 1.330 0.190

Grand Teton 2002 1.867 1.684 0.183 1.649 0.218 1.583 0.284

Grand Teton 2003 1.158 0.974 0.184 0.948 0.210 0.911 0.247

Yellowstone 2001 1.195 1.050 0.145 1.022 0.173 0.976 0.219

Yellowstone 2002 1.225 1.069 0.156 1.043 0.182 1.004 0.221

Yellowstone 2003 0.820 0.695 0.125 0.674 0.146 0.651 0.169

Unit 3

Bridger 2001 2.488 2.434 0.054 2.287 0.201 2.000 0.488

Bridger 2002 2.077 2.025 0.052 1.877 0.200 1.619 0.458
51

Unit Class I Area by Year

Baseline

Scenario 1 Scenario 2 Scenario 3

LNB/OFA LNB/OFA/SNCR LNB/OFA/SCR

98th Percentile 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

Bridger 2003 2.475 2.437 0.038 2.325 0.150 2.117 0.358

Fitzpatrick 2001 1.698 1.651 0.047 1.517 0.181 1.281 0.417

Fitzpatrick 2002 1.205 1.184 0.021 1.128 0.077 0.951 0.254

Fitzpatrick 2003 1.374 1.338 0.036 1.227 0.147 1.027 0.347

N. Absaroka 2001 0.779 0.750 0.029 0.670 0.109 0.537 0.242

N. Absaroka 2002 0.770 0.746 0.024 0.680 0.090 0.568 0.202

N. Absaroka 2003 0.490 0.474 0.016 0.430 0.060 0.356 0.134

Washakie 2001 1.216 1.171 0.045 1.048 0.168 0.843 0.373

Washakie 2002 1.062 1.033 0.029 0.947 0.115 0.800 0.262

Washakie 2003 0.656 0.629 0.027 0.553 0.103 0.426 0.230

Teton 2001 1.198 1.170 0.028 1.045 0.153 0.820 0.378

Teton 2002 1.021 0.985 0.036 0.909 0.112 0.793 0.228

Teton 2003 0.859 0.826 0.033 0.737 0.122 0.595 0.264

Grand Teton 2001 1.520 1.481 0.039 1.359 0.161 1.143 0.377

Grand Teton 2002 1.867 1.839 0.028 1.748 0.119 1.552 0.315

Grand Teton 2003 1.158 1.120 0.038 1.017 0.141 0.828 0.330

Yellowstone 2001 1.195 1.167 0.028 1.026 0.169 0.809 0.386

Yellowstone 2002 1.225 1.190 0.035 1.098 0.127 0.932 0.293

Yellowstone 2003 0.820 0.794 0.026 0.720 0.100 0.595 0.225
52

Table H.6 – Model Results for PacifiCorp – Naughton Units with Background Ammonia Levels based on IWAQM Recommendations

Unit Class I Area by Year

Baseline

Scenario 1 Scenario 2 Scenario 3

LNB/OFA LNB/OFA/SNCR LNB/OFA/SCR

98th Percentile 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

Unit 1

Bridger 2001 2.780 2.532 0.248 2.479 0.301 2.393 0.387

Bridger 2002 2.188 1.929 0.259 1.892 0.296 1.828 0.360

Bridger 2003 2.827 2.682 0.145 2.655 0.172 2.612 0.215

Fitzpatrick 2001 1.741 1.537 0.204 1.501 0.240 1.437 0.304

Fitzpatrick 2002 1.269 1.046 0.223 1.021 0.248 0.982 0.287

Fitzpatrick 2003 1.397 1.189 0.208 1.168 0.229 1.134 0.263

N. Absaroka 2001 0.773 0.678 0.095 0.662 0.111 0.636 0.137

N. Absaroka 2002 0.763 0.676 0.087 0.663 0.100 0.640 0.123

N. Absaroka 2003 0.481 0.431 0.050 0.422 0.059 0.409 0.072

Washakie 2001 1.240 1.134 0.106 1.115 0.125 1.086 0.154

Washakie 2002 1.145 1.030 0.115 1.009 0.136 0.976 0.169

Washakie 2003 0.666 0.608 0.058 0.598 0.068 0.580 0.086

Teton 2001 1.287 1.157 0.130 1.135 0.152 1.097 0.190

Teton 2002 0.998 0.898 0.100 0.881 0.117 0.857 0.141

Teton 2003 0.863 0.765 0.098 0.748 0.115 0.722 0.141

Grand Teton 2001 1.657 1.528 0.129 1.504 0.153 1.457 0.200

Grand Teton 2002 2.042 1.856 0.186 1.818 0.224 1.751 0.291

Grand Teton 2003 1.192 1.052 0.140 1.028 0.164 0.987 0.205

Yellowstone 2001 1.243 1.137 0.106 1.112 0.131 1.067 0.176

Yellowstone 2002 1.287 1.154 0.133 1.132 0.155 1.096 0.191

Yellowstone 2003 0.860 0.754 0.106 0.736 0.124 0.705 0.155

Unit 2

Bridger 2001 2.780 2.460 0.320 2.396 0.384 2.319 0.461

Bridger 2002 2.188 1.891 0.297 1.848 0.340 1.775 0.413

Bridger 2003 2.827 2.623 0.204 2.579 0.248 2.504 0.323

Fitzpatrick 2001 1.741 1.483 0.258 1.439 0.302 1.360 0.381

Fitzpatrick 2002 1.269 1.020 0.249 0.978 0.291 0.930 0.339
53

Unit Class I Area by Year

Baseline

Scenario 1 Scenario 2 Scenario 3

LNB/OFA LNB/OFA/SNCR LNB/OFA/SCR

98th Percentile 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

Fitzpatrick 2003 1.397 1.181 0.216 1.140 0.257 1.082 0.315

N. Absaroka 2001 0.773 0.655 0.118 0.636 0.137 0.603 0.170

N. Absaroka 2002 0.763 0.657 0.106 0.641 0.122 0.614 0.149

N. Absaroka 2003 0.481 0.417 0.064 0.406 0.075 0.391 0.090

Washakie 2001 1.240 1.084 0.156 1.059 0.181 1.016 0.224

Washakie 2002 1.145 0.997 0.148 0.971 0.174 0.928 0.217

Washakie 2003 0.666 0.569 0.097 0.558 0.108 0.540 0.126

Teton 2001 1.287 1.122 0.165 1.090 0.197 1.035 0.252

Teton 2002 0.998 0.870 0.128 0.848 0.150 0.819 0.179

Teton 2003 0.863 0.744 0.119 0.725 0.138 0.694 0.169

Grand Teton 2001 1.657 1.495 0.162 1.455 0.202 1.386 0.271

Grand Teton 2002 2.042 1.794 0.248 1.746 0.296 1.661 0.381

Grand Teton 2003 1.192 0.986 0.206 0.951 0.241 0.895 0.297

Yellowstone 2001 1.243 1.085 0.158 1.056 0.187 1.000 0.243

Yellowstone 2002 1.287 1.119 0.168 1.091 0.196 1.047 0.240

Yellowstone 2003 0.860 0.726 0.134 0.703 0.157 0.665 0.195

Unit 3

Bridger 2001 2.780 2.713 0.067 2.493 0.287 2.183 0.597

Bridger 2002 2.188 2.131 0.057 1.968 0.220 1.729 0.459

Bridger 2003 2.827 2.783 0.044 2.649 0.178 2.383 0.444

Fitzpatrick 2001 1.741 1.691 0.050 1.550 0.191 1.304 0.437

Fitzpatrick 2002 1.269 1.247 0.022 1.147 0.122 0.948 0.321

Fitzpatrick 2003 1.397 1.359 0.038 1.241 0.156 1.036 0.361

N. Absaroka 2001 0.773 0.744 0.029 0.665 0.108 0.534 0.239

N. Absaroka 2002 0.763 0.739 0.024 0.674 0.089 0.566 0.197

N. Absaroka 2003 0.481 0.465 0.016 0.419 0.062 0.347 0.134

Washakie 2001 1.240 1.193 0.047 1.067 0.173 0.855 0.385

Washakie 2002 1.145 1.112 0.033 1.017 0.128 0.852 0.293
54

Unit Class I Area by Year

Baseline

Scenario 1 Scenario 2 Scenario 3

LNB/OFA LNB/OFA/SNCR LNB/OFA/SCR

98th Percentile 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

Washakie 2003 0.666 0.638 0.028 0.560 0.106 0.430 0.236

Teton 2001 1.287 1.231 0.056 1.077 0.210 0.882 0.405

Teton 2002 0.998 0.966 0.032 0.885 0.113 0.763 0.235

Teton 2003 0.863 0.829 0.034 0.740 0.123 0.597 0.266

Grand Teton 2001 1.657 1.591 0.066 1.414 0.243 1.188 0.469

Grand Teton 2002 2.042 2.008 0.034 1.840 0.202 1.533 0.509

Grand Teton 2003 1.192 1.155 0.037 1.045 0.147 0.847 0.345

Yellowstone 2001 1.243 1.190 0.053 1.045 0.198 0.846 0.397

Yellowstone 2002 1.287 1.251 0.036 1.128 0.159 0.969 0.318

Yellowstone 2003 0.860 0.831 0.029 0.752 0.108 0.618 0.242

Table H.7 – Model Results for PacifiCorp – Wyodak Unit

Unit Class I Area by Year

Baseline Scenario 1 Scenario 2 Scenario 3

98th Percentile 

[Δdv]

LNB/OFA LNB/OFA/SNCR LNB/OFA/SCR

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

98th Percentile 

[Δdv]

Visibility 

Improvement 

[Δdv]

Unit 1

Badlands 2001 0.506 0.399 0.107 0.341 0.165 0.192 0.314

Badlands 2002 0.630 0.497 0.133 0.425 0.205 0.258 0.372

Badlands 2003 0.614 0.481 0.133 0.410 0.204 0.238 0.376

Wind Cave 2001 0.655 0.516 0.139 0.444 0.211 0.241 0.414

Wind Cave 2002 0.773 0.602 0.171 0.522 0.251 0.259 0.514

Wind Cave 2003 0.948 0.743 0.205 0.631 0.317 0.338 0.610