Minnesota Pollution Control Agency 

520 Lafayette Road North I St. Paul, MN 55155-4194 1 651-296-6300 1 800-657-3864 1 651-282-5332 TTY I www.pca.state.rnn.us 

December 30,2009 

Mr. Bharat Mathur 

Acting Regional Administrator (AR-19J) 

U. S . Environmental Protection Agency 

Region V 

77 West Jackson Boulevard 

Chicago, Illinois 60604 

RE: State Implementation Plan for Regional Haze 

Dear Mr. Mathur: 

The Minnesota Pollution Control Agency (MPCA) hereby submits to the U.S. Environmental 

Protection Agency (EPA) a revision to Minnesota's State Implementation Plan (SIP), pursuant to 

the federal Regional Haze Rule (40 CFR 5 1.300 - 5 1.309). 

This revision describes how Minnesota intends to implement the Regional Haze Rule in order to 

reduce regional haze in the Boundary Waters Canoe Area Wilderness and Voyageurs National 

Park, as well as in Class I areas outside of Minnesota where visibility is impacted by emissions 

from Minnesota. 

In addition to fulfilling the SIP requirement under the regional haze rule, this revision meets 

Minnesota's requirements under Clean Air Act Section 1 lO(a)(2)(D)(i) for a SIP that contains 

adequate provisions demonstrating that emissions from Minnesota will not interfere with 

measures required for any other state to meet the implementation requirements related to 

regional haze and visibility. 

Please contact Catherine Neuschler, of my staff, at 651-757-2607, if you have any questions 

regarding this submittal. 

Sincerely, 

3 

Paul Eger 

Commissioner 

Enclosures 

cc: Kathleen D 'Agostino, EPA Region V (w/enclosures) 

St.Paul ( Brainerd I Detroit Lakes I Duluth 1 Mankato / Marshall I Rochester I Willmar 1 Printed on 100%post-consumer recycled paper 

b 
 

Regional Haze

State Implementation 

Plan

December 2009
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Executive Summary

The state of Minnesota is home to two federal Class I areas, the Boundary Waters Canoe Area Wilderness 

(BWCAW) and Voyageurs National Park (VNP), located along the state’s border with Canada. In 

compliance with the Regional Haze Rule promulgated in 1999, the Minnesota Pollution Control Agency 

(MPCA) is submitting to the U.S. Environmental Protection Agency (EPA) this State Implementation 

Plan (SIP) to reduce haze and meet the goal of no man-made visibility impairment in the Class I areas by 

2064. 

Current visibility conditions, in deciviews, are: 

Baseline Conditions Natural Conditions 

Class I area 20% Worst Days 20% Best Days 20% Worst Days 20% Best Days 

BWCAW 19.9 6.4 11.6 3.4 

VNP 19.5 7.1 12.2 4.3 

The main pollutants contributing to visibility impairment in Minnesota’s Class I areas are ammonium 

sulfate, ammonium nitrate, and organic carbon. Modeling indicates that the organic carbon is biogenic, 

so the MPCA chose to focus control measures on the anthropogenic emissions of nitrogen oxides (NOX) 

and sulfur dioxide (SO2) that lead to formation of nitrate and sulfate. The main contributors of SO2 are 

electric generating units (EGUs), while the main contributors of NOX are motor vehicles, both on and off 

road. The main states whose emissions contribute to visibility impairment in BWCAW and VNP are: 

Minnesota, Wisconsin, Illinois, Iowa, Missouri, and North Dakota. 

Minnesota has several sources subject to Best Available Retrofit Technology (BART) requirements, 

namely EGUs and taconite pellet furnaces. Many of Minnesota’s EGUs are planning or have begun 

emission reduction projects. The MPCA made BART determinations for each subject-to-BART EGU, 

though in many cases already planned controls were deemed equivalent to BART. For the taconite 

furnaces, BART for NOX is an operating standard of good combustion practices in combination with 

some proposed process changes, while BART for PM is equivalent to the taconite Maximum Available 

Control Technology (MACT) standard, and BART for SO2 is generally existing particulate scrubbers 

optimized for SO2 removal. The MPCA is also requiring application of better emission measurement 

systems to set a NOX BART emission limit, SO2 limits at lines that burn high sulfur fuels, and determine 

compliance. Final BART emission limits, where not already available, will be submitted prior to the Five 

Year SIP Assessment. 

Minnesota’s long-term strategy includes the implementation of several federal programs, including BART 

and the Clean Air Interstate Rule (CAIR), over the next several years in Minnesota and the surrounding 

states. It also includes a target for a 30% reduction in combined NOX and SO2 emissions by 2018 from 

point sources in Northeastern Minnesota that emit over 100 tons per year of either NOX or SO2. 

Based on the emission reductions currently known to be reasonable, Minnesota has established the 

following reasonable progress goals, in deciviews: 

Class I area 20% Worst Days 20% Best Days 

BWCAW 18.6 6.4 

VNP 18.9 7.1 

Minnesota will continue to evaluate control strategies that have shown the potential to result in reasonable 

emission reductions, and expects the contributing states to do the same. Due to this ongoing evaluation, 

Minnesota expects to submit additional control strategies and a revised reasonable progress goal in the 

Five Year SIP assessment.
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Executive Summary ....................................................................................................................................... i

Regional Haze Glossary of Terms ............................................................................................................. viii

Chapter 1. Background and Overview ........................................................................................................ 11

General Background / History of Federal Regional Haze Rule .............................................................. 11

Minnesota’s Class I areas ....................................................................................................................... 12

Chapter 2. General Planning Provisions .................................................................................................... 13

Table 2.1: Stakeholder and Public Meetings ...................................................................................... 13

Chapter 3. Regional Planning and State Consultation ............................................................................... 15

Regional Planning................................................................................................................................... 15

Figure 3.1: Geographical Areas of Regional Planning Organizations ............................................... 15

Consultation Across RPOs ..................................................................................................................... 16

Technical Consultation ....................................................................................................................... 16

Table 3.1: Technical Committee Structure for CENRAP and MRPO; Minnesota Participants ....... 16

State Consultation ................................................................................................................................... 17

Northern Class I Area Consultation ................................................................................................... 18

Participants ..................................................................................................................................... 18

Process ........................................................................................................................................... 18

Chapter 4. State and Federal Land Manager Coordination ........................................................................ 20

Consultation During SIP Development .................................................................................................. 20

Official Notice and Consultation ............................................................................................................ 21

Chapter 5. Assessment of Visibility Conditions in Class I areas ............................................................... 22

Baseline, Natural and Current Conditions .............................................................................................. 22

Figure 5.1: Uniform Rate of Progress (URP) to Achieve Natural Conditions in 60 Years ................ 22

Default and refined values for natural visibility conditions ............................................................... 23

Consultation regarding the visibility metrics ..................................................................................... 24

Baseline Visibility Conditions ................................................................................................................ 24

Table 5.1: Monthly fS(RH) and fL(RH) values ................................................................................. 25

Natural Visibility Conditions .................................................................................................................. 27

Table 5.2: Visibility Metrics for Minnesota’s Class I areas ............................................................... 27

Table 5.3: Adjusted Visibility Metrics in dv for Northern Class I areas ............................................ 28

Table 5.4: Northern Class I areas URP in dv; Adjusted Data ............................................................ 28

Figure 5.2: Uniform Rate of Progress for BWCAW .......................................................................... 29

Figure 5.3: Uniform Rate of Progress for VNP .................................................................................. 29

Updated Visibility Conditions ................................................................................................................ 30

Table 5.5: Visibility Conditions 2005 - 2007 ..................................................................................... 30

Chapter 6. Monitoring Strategy ................................................................................................................. 31

Current Monitoring Strategy .................................................................................................................. 31

Figure 6.1 CENRAP IMPROVE and IMPROVE Protocol Sites ....................................................... 32

Table 6.1: Active Minnesota PM2.5 Monitoring Sites ........................................................................ 32

Table 6.2: Active Minnesota PM10 Monitoring Sites ......................................................................... 33

Future Monitoring Strategy .................................................................................................................... 33

Special Monitoring Studies ................................................................................................................ 34

Chapter 7. Emission Inventory.................................................................................................................... 35

State Inventory – 2002 ............................................................................................................................ 35

Table 7.1: Minnesota 2002 Baseline Emissions Inventory Summary (tpy) ....................................... 35

Table 7.2: Minnesota 2005 Emissions Summary (tpy) ...................................................................... 36

Inventory Methodology ...................................................................................................................... 36

Modeling Inventory ................................................................................................................................ 36

Chapter 8. Modeling ................................................................................................................................... 37

The Modeling System ............................................................................................................................. 39

Model Year Chosen ................................................................................................................................ 39
iv 

Conceptual Description .......................................................................................................................... 40

Modeling/Analysis Protocol ................................................................................................................... 40

Emissions Preparations & Results .......................................................................................................... 41

The Base Year Inventory – 2002 ............................................................................................................ 41

The Future Year Inventory – 2018 ......................................................................................................... 41

Table 8.1: Minnesota Adjustments and Corrections to IPM Version 3.0 .......................................... 42

Table 8.2: IPM2.1.9 (VISTAS), and IPM3.0 “base” and “will do” Alterations ............................... 43

Minnesota Growth Changes in Minnesota(MRPO) 2018 Modeling Inventory ................................. 44

Controls on Future Year Inventory .................................................................................................... 44

Table 8.3: Annual Minnesota 2002 and 2018 Emissions Totals in Tons .......................................... 45

Alternative EGU Emission Projections without CAIR. ..................................................................... 45

Table 8.4: Future Year Control Assumptions with and without CAIR .............................................. 46

MRPO Quality Assurance for Emissions Inventories ........................................................................ 47

Air Quality/Meteorology Preparations and Results ................................................................................ 48

Figure 8.1: Modeling Domains ......................................................................................................... 49

Performance Evaluation for Air Quality Models .................................................................................... 49

Meteorological Model Performance for the Base Year (2002) Data ................................................. 49

Air Quality Model Performance for the Base Year (2002) Inventory ................................................ 49

Comparison of Model Performance Evaluation for Nitrate on Individual Days ................................ 50

Figure 8.2: Observations and Predictions by Minnesota(MRPO) and CENRAP ................................... 50

Implications of the Performance Evaluation ...................................................................................... 51

Exploration of Potential Strategies for Demonstrating Reasonable Progress ......................................... 52

Figure 8.3: Contributions to Extinction in 2018 at BWCAW by Region for W20% Days ............... 53

Figure 8.4: Contributions to Extinction in 2018 at VNP by Region for W20% Days ....................... 53

Figure 8.5: % Contribution of NE and Rest of MN to BWCAW and VNP for W20% Days ........... 54

Figure 8.6: % Contribution of NE and Rest of MN to Max and Min Receptors for W20% Days .... 55

Figure 8.7: MN Contributions at Receptors Placed Throughout Class I Areas in 2018 ................... 55

Table 8.5: 2018 Annual Potentially Reasonable Control Measures Emissions for Point Sources .... 57

Figure 8.8: BWCAW 36-km Potentially Reasonable Emissions Reduction Results ........................ 58

Figure 8.9: VNP 36-km Potentially Reasonable Emissions Reduction Results ................................ 58

Reasonable Progress Strategy and Goals ................................................................................................ 59

Table 8.6: Reasonable Progress Goals for BWCAW and VNP ........................................................ 59

Figure 8.10: BWCAW 36-km Minnesota(MRPO) Results .................................................................... 59

Figure 8.11: VNP 36-km Minnesota(MRPO) Results ........................................................................... 60

Supplemental Analysis/ Weight of Evidence Determination ................................................................. 60

Table 8.7: Visibility Projections to 2018 for the W20% Days ......................................................... 61

Table 8.8: Relative Response Factors to 2018 for the W20% Days ................................................. 61

Table 8.9: Visibility Projections to 2018 using 2002 and 2005 Meteorology for the W20% Days .. 63

Table 8.10: RRFs for 2018 using 2002 and 2005 Meteorology for the W20% ................................ 64

Data Access ............................................................................................................................................ 64

Chapter 9. Best Available Retrofit Technology .......................................................................................... 65

BART-Eligible Sources in Minnesota .................................................................................................... 65

Table 9.1: Minnesota Facilities with BART-eligible Units ................................................................ 65

Determination of Sources Subject to BART .......................................................................................... 67

Table 9.2: Facilities with Units Subject to BART in Minnesota ........................................................ 68

Determination of BART Requirements for Subject-to-BART Sources ................................................. 69

EGU BART Determinations .............................................................................................................. 69

Table 9.3: Planned Control Upgrades by EGUs and PM Contribution to Visibility Impairment ...... 70

Table 9.4: NOX and SO2 BART Determinations for EGUs ............................................................... 71

Visibility Improvement .................................................................................................................. 71

Taconite BART Determinations ......................................................................................................... 71
v 

Table 9.5: Characteristics of Minnesota Taconite Pellet Furnaces ................................................... 72

BART Alternative .............................................................................................................................. 74

BART Implementation ....................................................................................................................... 75

Table 9.6: SO2 BART Determinations for Units Where a Full BART Analysis Was Conducted ..... 77

Table 9.7: NOX BART Determinations for Units Where a Full BART Analysis Was Conducted .... 80

Chapter 10. Reasonable Progress Goals and Long-Term Strategy ............................................................. 83

Consultation ............................................................................................................................................ 83

Basis for emission reduction obligations ................................................................................................ 83

Baseline inventory .............................................................................................................................. 84

Minnesota’s Impact on Class I areas .................................................................................................. 84

Table 10.1: Class I areas Impacted by Minnesota .............................................................................. 84

States Impacting Minnesota’s Class I areas ....................................................................................... 85

Table 10.2: Percentage Contributions by State to Light Extinction ................................................... 85

Pollutants and Sources Impacting Minnesota’s Class I areas ............................................................ 86

Figure 10.3: 2002 Observations and 2018 Projections in Extinction by Species W20% Days.......... 86

Figure 10.4: NOX and SO2 Emissions in Minnesota by Source Category .......................................... 86

Figure 10.5: BWCAW 2018 Extinction by Sector for each Specie, W20% Days ............................. 87

Figure 10.6: VNP 2018 Extinction by Sector for each Specie, W20% Days ..................................... 87

Guidance in Determining RPG ............................................................................................................... 88

Approach to Determining RPG .............................................................................................................. 88

Share of Emission Reductions ................................................................................................................ 91

Minnesota’s Long-Term Strategy ........................................................................................................... 91

Emission reductions due to ongoing air pollution programs .............................................................. 91

Clean Air Interstate Rule (CAIR) .................................................................................................. 92

Table 10.3: IPM 3.0 Predictions for 2018 .......................................................................................... 92

Best Available Retrofit Technology (BART) ................................................................................ 93

Other Federal Programs ................................................................................................................. 94

PM2.5 and Ozone SIPs .................................................................................................................... 94

Additional Emission limitations and schedules of compliance .......................................................... 94

Plan for Emission Reductions in Northeast Minnesota ................................................................. 94

Table 10.4: NE Minnesota Emission Reduction Target ..................................................................... 96

Table 10.5: BART and Northeast Minnesota Plan Timeline ............................................................. 98

Measures to mitigate the impacts of construction activities ............................................................... 99

Source retirement and replacement schedules .................................................................................. 100

Agricultural and forestry smoke management ................................................................................. 100

Impact of Fires on Visibility ........................................................................................................ 100

Table 10.6: W20% Days with Highest OC and EC Light Extinction .............................................. 102

Agricultural Smoke Management ................................................................................................ 102

Forestry Smoke Management ...................................................................................................... 103

Future of SMP and Fires .............................................................................................................. 105

Enforceability of emission limitations and control measures ........................................................... 105

Anticipated net effect on visibility resulting from projected changes to emissions ......................... 106

Potential Future Projects and Impacts .............................................................................................. 106

Reasonable Progress Goals ................................................................................................................... 107

Table 10.7: Reasonable Progress Goals for Class I areas ................................................................ 107

Factors Impacting RPG .................................................................................................................... 107

International Emissions ................................................................................................................ 107

Emissions from Contributing States ............................................................................................ 107

Table 10.8: Alternate Goals for Class I areas ................................................................................... 109

Table 10.9: Visibility Conditions, URP and RPG for Minnesota’s Class I areas (dv) ..................... 110

Steps in Reviewing Control Strategies and Revising RPG .............................................................. 110
vi 

Timeline for Reviewing Control Strategies ...................................................................................... 111

Chapter 11. Periodic Plan Revisions and Determination of Adequacy.................................................... 112

2018 SIP Revision ................................................................................................................................ 112

Five Year Report .................................................................................................................................. 112

Actions to be Taken Prior to Five Year Report ................................................................................ 112

Table 11.1: Activities to be Completed Prior to Five Year SIP Assessment ................................... 112

Contents of Five Year Report ........................................................................................................... 113

BART Limits ............................................................................................................................... 113

Northeast Minnesota Plan Evaluation and Taconite Retrofit Requirements................................ 113

Reasonable Progress Update ........................................................................................................ 114

Adequacy Determination ............................................................................................................. 114

Appendix 1.1: Benefits of Improved Visibility ........................................................................................ 118

Appendix 1.2: EPA SIP Submittal Checklist ............................................................................................ 122

Appendix 2.1: Documentation of legal authority and compliance with State procedure.......................... 128

Appendix 2.2: Public Notices .................................................................................................................. 134

Appendix 2.3: Certification of Public Meeting ......................................................................................... 154

Appendix 2.4: Public Comments on Draft Haze SIP and MPCA Response ............................................. 165

Appendix 2.5: Interim Comments on Revised Regional Haze SIP and MPCA Response ....................... 328

Appendix 2.6: Public Comments on Revised Regional Haze SIP and MPCA Response ......................... 398

Appendix 3.1: Summary of Technical Information .................................................................................. 592

Appendix 3.2: Formal Consultation Letter ............................................................................................... 623

Appendix 4.1: Agency Contacts Provided to FLMs ................................................................................. 650

Appendix 5.1: Determination of Visibility Conditions ............................................................................. 651

Appendix 5.2: Impact of Missing Data on Worst Days at Midwest Northern Class I areas ..................... 653

Table 5.2.1: Northern Class I area Days Exceeding p80, Despite Missing Components ................ 654

Table 5.2.2: Comparison of Average of 20% Worst Days ............................................................... 654

Figure 5.2.1: BWCAW 2000 Light Extinction by Species (20% Worst Days) ............................... 655

Figure 5.2.2: BWCAW 2001 Light Extinction by Species (20% Worst Days) ............................... 655

Figure 5.2.3: BWCAW 2002 Light Extinction by Species (20% Worst Days) ............................... 656

Figure 5.2.4: BWCAW 2003 Light Extinction by Species (20% Worst Days) ............................... 656

Figure 5.2.5: BWCAW 2004 Light Extinction by Species (20% Worst Days) ............................... 657

Figure 5.2.6: BWCAW 2005 Light Extinction by Species (20% Worst Days) ............................... 657

Figure 5.2.7: VNP 2000 Light Extinction by Species (20% Worst Days) ....................................... 658

Figure 5.2.8: VNP 2001 Light Extinction by Species (20% Worst Days) ....................................... 658

Figure 5.2.9: VNP 2002 Light Extinction by Species (20% Worst Days) ....................................... 659

Figure 5.2.10: VNP 2003 Light Extinction by Species (20% Worst Days) ..................................... 659

Figure 5.2.11: VNP 2004 Light Extinction by Species (20% Worst Days) ..................................... 660

Figure 5.2.12: VNP 2005 Light Extinction by Species (20% Worst Days) ..................................... 660

Appendix 5.3: Additional Visibility Metrics ............................................................................................ 661

Table 5.3.1: Northern Class I areas Visibility Metrics in dv; Old IMPROVE Equation ................. 661

Table 5.3.2: Northern Class I areas URP in dv; Old IMPROVE Equation ...................................... 661

Table 5.3.3: Northern Class I areas Visibility Metrics in dv; New IMPROVE Equation ................ 661

Table 5.3.4: Northern Class I areas URP in dv; New IMPROVE Equation .................................... 662

Appendix 6.1: Monitoring and Data Analysis to Support the Regional Haze Rule ................................. 663

Appendix 7.1: Minnesota’s 2002 Emissions Inventory and Methodology .............................................. 682

Appendix 9.1: Identification of BART-Eligible Sources in Minnesota ................................................... 697

Table 9.1.1: Facilities Asked to Identify BART-Eligible Sources ................................................... 698

Appendix 9.2: BART Strategy, Modeling Protocols, Results, and Analyses .......................................... 705

Appendix 9.3: BART Determinations by MPCA – Taconite Facilities .................................................... 706

Table 9.3.1 U.S. Taconite Iron Ore Facility Location ..................................................................... 706

Figure 9.3.1: Diagram of Straight-Grate Induration Furnace ........................................................... 709
vii 

Figure 9.3.2: Diagram of a Grate-Kiln Induration Furnace .............................................................. 710

Table 9.3.2: Characteristics of Minnesota Taconite Pellet Furnaces ............................................... 711

Appendix 9.4: BART Determinations by MPCA – EGU ......................................................................... 836

Table 9.4.1: Subject-to-BART EGUs .............................................................................................. 837

Table 9.4.2: EGUs BART Proposals for PM ................................................................................... 837

Table 9.4.3: Visibility Impact of Direct PM Emissions ................................................................... 838

Appendix 9.5: BART Visibility Modeling ............................................................................................... 914

Appendix 9.6: Minnesota BART Rules ................................................................................................... 934

Appendix 9.7: Administrative Orders ...................................................................................................... 940

Appendix 10.1: Contribution Assessment Analysis................................................................................. 974

Table 10.1.1: MRPO Estimated Contributions to Light Extinction – Percentages .......................... 974

Figure 10.1.1: Back Trajectories for Light Extinction, 20% Worst Days ........................................ 975

Figure 10.1.2: AOIs for Minnesota’s Class I areas .......................................................................... 976

Figure 10.1.3: PSAT 2018 W20% Days Light Extinction from Minnesota..................................... 977

Figure 10.1.4: PSAT 2018 W20% Days Light Extinction at BWCAW by Source Region ............. 978

Figure 10.1.5: PSAT 2018 W20% Days Light Extinction at VNP by Source Region ..................... 979

Appendix 10.2: Minnesota Statute 216B.1692 ......................................................................................... 980

Appendix 10.3: EGU Air Emission Permits ............................................................................................. 983

Appendix 10.4: Concept Plan for Addressing Major Point Sources in Northeastern Minnesota ............. 985

Appendix 10.5: Factor Analysis of Control Strategies (EC/R Report) ..................................................... 993

Appendix 10.6: CENRAP Cost Curve Analysis of Control Strategies ..................................................... 994

Table 10.6.1: NOX Controls, Q/5D for BWCAW or VNP ............................................................... 995

Table 10.6.2: SO2 Controls, Q/5D for BWCAW or VNP ............................................................... 996

Appendix 10.7: Fire Emissions and Impact of Fire on Visibility ............................................................. 998

Figure 10.7.1: HYSPLIT and Fire Maps for 6/1/2002 ..................................................................... 999

Figure 10.7.2: HYSPLIT and Fire Map for 6/28/02 ......................................................................... 999

Figure 10.7.3: HYSPLIT Back Trajectories for 9/30/2000 .............................................................1000 

Figure 10.7.4: HYSPLIT Back Trajectories for 6/5/2003 ...............................................................1001

Figure 10.7.5: HYSPLIT Back Trajectories for 8/7/2003 .............................................................. 1002

Figure 10.7.6: Canadian Fire Hotspots for 8/5/2003 ...................................................................... 1002

Figure 10.7.7: HYSPLIT Back Trajectories for 8/25/2003 ............................................................ 1003

Figure 10.7.8: Canadian Fire Hotspots for 8/23/2003 .................................................................... 1003

Figure 10.7.9: HYSPLIT Back Trajectories for 7/26/2004 ............................................................ 1004

Figure 10.7.10: CWFIS Fire Hot Spots for 7/25/2004 ................................................................... 1005

Figure 10.7.11: CWFIS Fire Hot Spots for 7/27/2004 ................................................................... 1005

Appendix 10.8: EPA’s Certification of Smoke Management Plan ......................................................... 1007

References and Guidance Documents ..................................................................................................... 1009
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Regional Haze Glossary of Terms

• 20% Best Days – The days with the best visibility over the baseline or future period 

• 20% Worst Days – The days with the poorest visibility over the baseline or future period 

• BACT – Best Available Control Technology – Required for major sources or modifications under 

PSD. 

• BART – Best Available Retrofit Technology – Requires controls on certain types of sources built 

between 1962 – 1977 and generally grandfathered under most Clean Air Act programs 

• Baseline Conditions – Current visibility conditions, or visibility conditions over the baseline period 

• Baseline Period – As required by rule, the years 2000 - 2004 

• CAIR – Clean Air Interstate Rule – A cap and trade program covering 27 Eastern states to reduce 

emissions of NOX and SO2 from power plants. 

• CAMx – Comprehensive Air quality Model with eXtensions - A computer modeling system for the 

integrated assessment of gaseous and particulate air pollution. 

• CEMs – Continuous Emission Monitoring System 

• CENRAP – Central Regional Air Planning Association – Regional planning organization covering 

the central portion of the U.S, including states and tribal areas of Nebraska, Kansas, Oklahoma, 

Texas, Minnesota, Iowa, Missouri, Arkansas, and Louisiana 

• CIRA – Cooperative Institute for Research in the Atmosphere – Research institute contracted by the 

National Park Service to work on visibility information, including IMPROVE and VIEWS 

• CMAQ – Community Multi-Scale Air Quality model – Air Quality model used by many states and 

RPOs for estimating visibility conditions. 

• Deciview – Visibility unit used in the Regional Haze SIP; similar to a decibel, one deciview is the 

smallest change in visibility that is perceptive to the human eye. 

• EMS – Emissions Modeling System - Generates hourly speciated emissions on a gridded basis for 

input to an air quality model. 

• EGUs – Electric Generating Units – Utility power plants 

• HYSPLIT4 - HYbrid Single-Particle Lagrangian Integrated Trajectory – Model for computing simple 

air parcel trajectories to complex dispersion and deposition simulations. 

• IMPROVE – Interagency Monitoring of Protected Visual Environments – Cooperative program to 

monitor visibility in the Class I areas, http://vista.cira.colostate.edu/improve/ 

• LADCO – Lake Michigan Air Directors Consortium – Air quality planning organization for Illinois, 

Indiana, Michigan, Ohio, and Wisconsin; conducts air quality technical assessments 

• MM5 – Mesoscale Meteorological Model – A numerical model for weather prediction on scales from 

continental to one km. 

• Model Inventory – The emission inventory used in the atmospheric chemistry and transport modeling, 

usually different from the emission inventory submitted to the NEI. 

• MRPO – Midwest Regional Planning Organization – Regional planning organization for regional 

haze, covering the Midwest states (Illinois, Indiana, Michigan, Ohio, and Wisconsin) 

• Natural Conditions – Estimation of visibility without any man-made influence 

• NEI – National Emission Inventory – Compilation of emissions by pollutant, source category, and 

geographic for each state; required by the EPA on a three-year cycle 
x

• PiG – Plume in Grid – Tool within the modeling system to track individual plume segments from 

each point source, rather than immediately dispersing the individual point sources emissions into the 

grid cell. 

• PSAT – Particulate Matter Source Apportionment Technology – Part of CAMx that tracks the 

original source of particulate species by geographic region and source category 

• PSD – Prevention of Significant Deterioration – A program established by the Clean Air Act that 

limits the amount of additional air pollution that is allowed in Class I and Class II areas. 

• RPG – Reasonable Progress Goal – Visibility goal for 2018 set by the state in the SIP; usually used to 

refer to the visibility goal for the 20% worst days 

• SCC - Source Classification Code – Code used by EPA to classify different types of air quality 

inventory emission sources. 

• SMOKE – Sparse Matrix Object Kernel Emission – EPA processor for preparation of emission data. 

• SMP – Smoke Management Plan – Plan to reduce the impact of prescribed fire on air quality. 

• URP – Uniform Rate of Progress – The constant rate of visibility improvement needed to meet 

natural conditions on the 20% worst days in 2064 

• VIEWS – Visibility Information Exchange Web System – Web repository of visibility information, 

http://vista.cira.colostate.edu/views/ 

For a more detailed haze glossary, see: 

http://vista.cira.colostate.edu/improve/Education/Glossary/glossary.htm
11 

Chapter 1. Background and Overview

General Background / History of Federal Regional Haze Rule 

In amendments to the Clean Air Act (CAA) in 1977, Congress added Section 169 (42 U.S.C. § § 7491), 

setting forth a national visibility goal of restoring pristine conditions in national parks and wilderness 

areas. These areas were designated as Class I areas, because of their general nature as areas most free 

from air pollution and visibility problems. Section 169 states: 

“Congress hereby declares as a national goal the prevention of any future, and the 

remedying of any existing, impairment of visibility in mandatory Class I Federal areas 

which impairment results from man-made air pollution.” 

Over the following years modest steps were taken to address the visibility problems in Class I areas. The 

control measures taken mainly addressed “plume blight,” the visual impairment of air quality that 

manifests itself as a coherent plume from specific pollution sources, such as a power plant smoke stack, 

emitting pollutants into a stable atmosphere. These plume blight control measures did little to address 

regional haze issues in the Eastern United States. 

When the CAA was again amended in 1990, Congress added Section 169B (42 U.S.C. § § 7492), 

authorizing further research and regular assessments of the progress made towards visibility goals. In 

1993, the National Academy of Sciences concluded “current scientific knowledge is adequate and control 

technologies are available for taking regulatory action to improve and protect visibility.”1 

Section 169B(f) of the CAA authorized creation of visibility transport commissions and set forth their 

duties, and specifically mandated creation of the Grand Canyon Visibility Transport Commission 

(GCVTC) to make recommendations to the U.S. Environmental Protection Agency (EPA) for the region 

affecting visibility in Grand Canyon National Park. After four years of research and policy development, 

GCVTC submitted its report to EPA in June 1996.2

 This report, as well as other research reports prepared 

by GCVTC, contributed information to EPA’s development of the federal Regional Haze Rule (RHR). 

EPA’s Regional Haze Rule was adopted July 1, 1999, and went into effect on August 30, 1999. The RHR 

is intended to achieve national visibility goals by 2064. The rulemaking addressed the combined visibility 

effects of various pollution sources over a wide geographic region, meaning that many states – even those 

without Class I areas – are required to participate in haze reduction efforts. EPA designated five Regional 

Planning Organizations (RPOs) to assist with the coordination and cooperation needed to address 

visibility and haze issues. Those states and tribes that make up the midsection of the contiguous United 

States, including Minnesota, were designated as the Central Regional Air Planning Association 

(CENRAP). 

On May 24, 2002 the U. S. Court of Appeals, D. C. Circuit Court, ruled on a challenge to the RHR 

brought by the American Corn Growers Association. The Court denied industry’s challenge to the rule’s 

goals of natural visibility and no degradation, and remanded to EPA the Best Available Retrofit 

Technology (BART) provisions of the rule.3

 

EPA proposed rule revisions pursuant to the remand, and final amendments to the Regional Haze Rule 

and guidelines for BART were finalized on June 15, 2005. In the initial rule, EPA had required states to 

consider the collective impact of BART sources on visibility. The Court ruled that this unfairly 

 

1

National Research Council, Commission on Geosciences, Environment and Resources, 1993. 

2

 GCVTC, 1996. 

3

 American Corn Growers Association v. EPA. 
12 

constrained the states’ otherwise broad authority to make BART determinations, and so subsequent 

revisions give states more discretion and provide a process for states to consider BART determination on 

a facility-by-facility basis. 

Minnesota’s Class I areas 

Minnesota has two Federal Class I areas within its borders: the Boundary Waters Canoe Area Wilderness 

and Voyageurs National Park. 

The Boundary Waters Canoe Area Wilderness (BWCAW) is part of the Superior National Forest, which 

was established by Presidential proclamation in 1909. BWCAW is a 1-million acre federally designated 

wilderness; it is the only wilderness of substantial size east of the Rocky Mountains and north of the 

Everglades and is the most heavily used wilderness area in the United States with about 200,000 annual 

visitors. The Boundary Waters Canoe Area Wilderness Act, which banned logging and mining, phasedout snowmobiling, and limited motorboat use in BWCAW, was signed by President Jimmy Carter on 

October 21, 1978.4

 

Voyageurs National Park (VNP) is a water-based park named for the French-Canadian voyageurs that 

traveled through the area in canoes while trading fur and other goods. Designation as a National Park was 

first proposed in 1891, and Voyageurs was officially established as a National Park in 1975. VNP covers 

218,054 acres on the northern border of Minnesota, abutting BWCAW and sharing 55 miles of the 

Canadian border.5

 

Minnesota has not had an approved Visibility Plan for its Class I areas, and has b een under a federal 

implementation plan for visibility as designated in 40 CFR 52.26, 52.28 and 52.29. 

In accordance with the Regional Haze Rule, Minnesota has determined that emission sources within 

Minnesota have or may have impacts both on the Class I areas within Minnesota (BWCAW and VNP) 

and on the Isle Royale Class I area in the state of Michigan. Therefore, Minnesota submits this SIP to 

fulfill the requirements of the Regional Haze Rule and help reduce visibility impairment in the Northern 

Class I areas mentioned above. 

In addition, Minnesota believes that improved visibility and the removal of haze-causing particles from 

the atmosphere in order to promote increased visibility in Class I areas will result in environmental and 

economic benefits and improved health for Minnesota’s citizens and those in areas downwind of 

Minnesota. Benefits of improved visibility can be found in Appendix 1.1. 

To facilitate the review of this State Implementation Plan (SIP) by the EPA, Federal Land Managers 

(FLMs), stakeholders and the public, Appendix 1.2 provides a modified version of EPA’s SIP submittal 

checklist, which serves as a guide to locating 40 CFR 51.308 requirements. 

 

4

 BWCAW and U.S.D.A., Forest Service. Boundary Waters Canoe Area Wilderness and Superior National Forest

(web pages) 

5

 U.S. National Park Service, Voyageurs National Park (webpage) 
13 

Chapter 2. General Planning Provisions

Pursuant to the requirements of 40 CFR 51.308(a) and (b), Minnesota submits this SIP to comply with the 

Regional Haze Rule, adopted to meet the requirements set forth in the Clean Air Act. Elements of this 

plan address the core requirements pursuant to 40 CFR 51.308(d) and the Best Available Retrofit 

Technology (BART) components of 40 CFR 51.308(e). In addition, this SIP addresses Regional 

Planning, state and FLM coordination, and contains a commitment to provide ongoing plan revisions and 

adequacy determinations. 

The Minnesota Pollution Control Agency (MPCA) has the legal authority to adopt this SIP revision and 

has done so in accordance with state laws and rules. MPCA’s legal authority and compliance with state 

procedures is documented through a letter from the Minnesota Attorney General’s office, attached as 

Appendix 2.1. 

Minnesota provided multiple opportunities for stakeholders to comment on the technical background and 

other issues regarding the development of this SIP, both informally and through the formal public notice 

and comment period. The following table lists non-mandatory stakeholder meetings held by the MPCA, 

along with the public meeting. Stakeholders were encouraged to comment informally throughout the SIP 

development process, and updates were posted on the MPCA’s Minnesota Regional Haze Plan webpage.6

Table 2.1: Stakeholder and Public Meetings 

Date Subject and Content 

January 31, 2007 Review of Technical Information 

April 12 – April 27, 2007 Meetings with individual stakeholder groups concerning long-term 

strategy (Northeast Minnesota Plan) 

May 15, 2007 Update of technical information 

Control Strategy Analysis 

Long-term Strategy 

October 23, 2007 Draft Regional Haze SIP is Information Item at MPCA Citizens’ 

Board 

April 10, 2008 Official public meeting on Draft Regional Haze SIP. 

May 7, 2008 Stakeholder conference call on Draft Regional Haze SIP 

June 24, 2008 Final Initial Regional Haze SIP Information Item at MPCA 

Citizens’ Board 

September 22, 2009 Revised Draft Regional Haze SIP Information Item at MPCA 

Citizens’ Board 

October 27, 2009 Revised Draft Regional Haze SIP Decision Item at MPCA 

Citizens’ Board 

December 15, 2009 Continuation of Revised Draft Regional Haze SIP Decision Item 

at MPCA Citizens’ Board 

A public notice of the opportunity to comment on the SIP was published on February 25, 2008 in the 

Minnesota State Register and contained notice of a public meeting to be held on April 10, 2008, with the 

comment period to close on April 16, 2008. The comment period was later extended to May 16, 2008. 

 

6

 Addresses for all web pages referenced in this document can be found the in “References and Guidance 

Documents” section. 
14 

During the initial public notice period, the draft SIP document was made available on the MPCA’s 

Regional Haze webpage. In addition, a copy was made available at MPCA’s Headquarters, 520 Lafayette 

Road N., Saint Paul, Minnesota and at MPCA’s regional office in Duluth. 

Copies of the initial public notice and the notice of extension are attached in Appendix 2.2. A notice of 

the SIP revision and public comment period was also emailed to the MPCA’s list of stakeholders 

interested in regional haze and placed on MPCA’s public notice and Regional Haze web pages. 

Minnesota held an official public meeting regarding the SIP revision on April 10, 2008; the meeting was 

based in St. Paul with videoconferencing to Duluth. Documentation of the public meeting is included in 

Appendix 2.3. 

Public comments made during the notice period and at the public meeting are included in Appendix 2.4. 

MPCA’s response to the comments is also provided, which describes how MPCA considered and 

incorporated public comments into this final SIP document. 

The MPCA’s response to comments, along with Minnesota’s proposed removal from the Clean Air 

Interstate Rule, necessitated several changes to the SIP. The MPCA communicated with the stakeholders, 

including the Federal Land Managers, who had made the most extensive comments on the initial draft 

SIP. These stakeholders made some interim comments, and requested that the MPCA place the SIP back 

on public notice. The interim comments are included in Appendix 2.5, along with the MPCA’s response, 

and were included in the public notice of the revised SIP. The second public notice is included in 

Appendix 2.2. Comments received on the revised SIP and the MPCA’s response are included in 

Appendix 2.6. 
15 

Chapter 3. Regional Planning and State Consultation

Because regional haze is caused by a wide variety of pollution sources dispersed over a large geographic 

area, the Regional Haze Rule places specific emphasis on having states work collaboratively through 

regional planning and consultation processes. 

Regional Planning 

In 1999, EPA and affected states/tribes agreed to create five RPOs to facilitate interagency coordination 

on Regional Haze implementation plans. Minnesota is a member of the Central Regional Air Planning 

Association (CENRAP). MPCA has also worked extensively with the Lake Michigan Air Directors 

Consortium/Midwest Regional Planning Organization (LADCO/MRPO),7

 because several states in 

MRPO have emissions that impact Minnesota’s Class I areas and Minnesota has emissions that impact a 

Class I area located in Michigan. 

Members of CENRAP include the states of Arkansas, Iowa, Kansas, Louisiana, Minnesota, Missouri, 

Nebraska, Oklahoma, and Texas; Tribes whose lands are within the geographical borders of these states 

are also members. Figure 3.1 shows a map of all five regional planning organizations. 

Figure 3.1: Geographical Areas of Regional Planning Organizations 

The governing body of CENRAP is the Policy Oversight Group (POG). The POG is made up of 18 

voting members representing the states and tribes within the CENRAP region and non-voting members 

representing local agencies, EPA, the Fish and Wildlife Service, Forest Service, and National Park 

Service. The POG facilitates communication with Federal Land Managers (FLMs), stakeholders, the 

public, and with CENRAP staff. 

Since its inception, CENRAP has established an active committee structure to address both technical and 

non-technical issues related to regional haze. This includes five standing workgroups: Data Analysis and 

 

7

 LADCO was formed to provide air quality technical assessments and assistance for Illinois, Indiana, Michigan, 

Ohio and Wisconsin; MRPO was formed to coordinate Regional Haze planning for those same states. LADCO was 

designated to receive federal funds on behalf of MRPO. 
16 

Monitoring; Emission Inventory; Modeling; Communications; and Implementation and Control 

Strategies. Participation in workgroups is open to all interested parties. Ad hoc workgroups may be 

formed by the POG to address specific issues. Ultimately, policy decisions are made by the POG. 

Consultation Across RPOs 

CENRAP has adopted the approach that the RHR requires the “states to establish goals and emission 

reduction strategies for improving visibility in all 156 mandatory Class I parks and wilderness areas,” and 

has provided a forum and structure for states to work together to achieve these goals. 

Minnesota also believes that the RHR encourages states and tribes to work together in regional 

partnerships beyond the RPOs when necessary, to ensure that each Class I host state consults with all 

those states whose emissions impact its Class I areas. 

Technical Consultation 

Minnesota participated in extensive consultation on technical work, both with CENRAP and MRPO. 

Like CENRAP, MRPO decisions and directions are established by the Air Directors from each state and 

are carried out by the technical workgroups. Although Minnesota does not actively participate in MRPO 

decision-making or communication processes, Minnesota staff members have actively participated in 

MRPO technical committees. 

CENRAP has an administrative director and a technical director. The technical committees are run by cochairs, which are staff volunteers from CENRAP affiliated states and Tribes, or representatives from 

industry with interests within the geographic area. Nearly all CENRAP technical work is conducted 

through contracts; mainly by ENVIRON and University of California-Riverside. 

MRPO has an administrative/technical director. The technical committees are run by MRPO staff. All 

technical work is coordinated by MRPO staff, and much of the technical work is conducted by MRPO 

staff with assistance from both member state staff and contractors. Table 3.1 lists the technical committee 

structure and Minnesota staff that actively participated in each technical committee. Technical 

committees in both organizations include representatives from states, EPA, FLMs, tribes and industry. 

Table 3.1: Technical Committee Structure for CENRAP and MRPO, and Minnesota Participants 

CENRAP: Administrative Director- Annette Sharp, Technical Director – Jeff Peltola* 

Committee Leader (co-chair) Minnesota Participant 

Data Analysis and Monitoring Brandon Krogh* (Minnesota Power) 

Scott Weir (Kansas) 

Gordon Andersson 

gordon.andersson@pca.state.mn.us 

Emission Inventory Wendy Vit (Missouri) Michael Smith 

michael.smith@pca.state.mn.us 

Modeling Lee Warden (Oklahoma)* 

Calvin Ku (Missouri) 

Margaret McCourtney 

margaret.mccourtney@pca.state.mn.us 

Implementation and Control 

Strategies 

Mark McCorkle (Arkansas) 

John Seltz (Minnesota) 

John Seltz 

john.seltz@pca.state.mn.us 

MRPO: Administrative/Technical Director- Mike Koerber

Committee Leader Minnesota Participant 

Data Analysis and Monitoring Donna Kenski N/A 

Emission Inventory Mark Janssen Chun Yi Wu 

chunyi.wu@pca.state.mn.us 

Margaret McCourtney 

margaret.mccourtney@pca.state.mn.us 

Modeling Kirk Baker* Margaret McCourtney 

margaret.mccourtney@pca.state.mn.us 

*These leaders no longer hold the position, but had either significant or sole contribution to the work. 
17 

Communication among technical committee members to develop consensus on various issues was 

conducted through conference calls and meetings during SIP development as follows: 

CENRAP calls and meetings: 

• Data Analysis and Monitoring – Monthly conference calls; 

• Emission Inventory – Calls on an as needed basis; no calls from May 2005 through May 2007. 

Met in joint conference call with modeling from June – September 2007; 

• Modeling – Bi-weekly conference call. 

Meetings are scheduled for all CENRAP participants and the POG two to four times per year as funding 

allows. 

MRPO calls and meetings:

• Data Analysis and Monitoring – Not applicable. Minnesota is not an active participant; 

• Emission Inventory – Monthly and/or as needed depending on needs for project input; 

• Modeling – Monthly and/or as needed depending on needs for project input. 

Meetings are scheduled separately for each technical committee, as new technical information is made 

available where sharing information is best done in person. The emissions inventory technical committee 

has exclusively shared information by conference call and e-mail. The modeling technical committee 

meets up to two times per year. Because of its centrally located staff, MRPO also communicates and 

provides data, tools and information individually to states based on specific needs. 

This SIP mainly utilizes modeling inputs and results developed by MRPO, along with some MRPO data 

analysis and technical support work. It also includes modeling and data analysis generated by the MPCA. 

The SIP also includes data analysis and other technical support documents prepared for CENRAP, and 

CENRAP modeling work primarily as supporting information. 

CENRAP data analyses, modeling results and other technical support documents were provided to 

CENRAP members through either CENRAP’s website or through a file transfer protocol (ftp). Similar 

information sharing was done using the LADCO website and LADCO agreed to house documents related 

to the Northern Class I area consultation process on its website. 

State Consultation 

A chief purpose of the RPO is to provide a means for states to confer on all aspects of regional haze, 

including consulting on reasonable progress goals and long-term strategies based on determinations of 

baseline and natural visibility conditions. CENRAP has provided a forum for the member states and 

Tribes to consult on the determination of visibility conditions in each of the Class I areas. 

Minnesota has worked with states that are members of CENRAP, MRPO, and the Western Regional Air 

Partnership (WRAP) to convene meetings of representatives from the states and Tribes that impact 

visibility in the four Northern Class I areas – BWCAW and VNP in Minnesota along with Isle Royale 

National Park and Seney Wilderness in Michigan – along with FLMs and EPA representatives involved 

with the Northern Class I areas. This group engaged in extensive consultation about visibility conditions 

and control strategies needed to improve visibility at these four Class I areas. 

By coordinating with CENRAP, MRPO and the other states whose emissions impact visibility in our 

Class I areas, Minnesota has worked to ensure that our BART determinations and the control strategies 

that comprise our long-term strategy provide sufficient reductions to mitigate the impact of emissions 

from sources inside Minnesota on affected Class I areas, as well as to encourage other states to take 

necessary measures to help improve visibility in the Class I areas located within Minnesota. 
18 

Northern Class I Area Consultation 

As described above, consultation among states is a requirement of the Regional Haze Rule. As part of the 

long-term strategy for regional haze, a state whose emissions are “reasonably anticipated” to contribute to 

impairment in other states’ Class I area(s) must consult with those states; likewise, a Class I host state 

must consult with those states whose emissions affect its Class I area(s) (40 CFR 51.308(d)(3)). Because 

many states that impact visibility in BWCAW and VNP are located outside of CENRAP, the MPCA 

helped convene the Northern Class I area Consultation process to ensure that Minnesota met the 

requirement of consulting with all states whose emissions may impact visibility in our Class I areas. 

Participants

The Northern Class I areas consultation process concerned visibility in BWCAW and VNP along with 

Isle Royale National Park and Seney Wilderness in Michigan, and included the states of Minnesota, 

Michigan, North Dakota, Wisconsin, Iowa, Illinois, Indiana, and Missouri. The consultation process also 

included representatives from other governments, such as the Ontario Ministry of the Environment and 

Tribes including the Leech Lake Band of Ojibwe, Mille Lacs Band of Ojibwe, Fond du Lac Band of Lake 

Superior Chippewa, Grand Portage Band of Chippewa, Upper/Lower Sioux, and Huron Potawatomi. 

The Northern Class I consultation process included representatives from federal agencies, including 

Federal Land Managers from the U.S. Department of the Interior National Park Service and U.S.D.A 

Forest Service, as well as representatives from EPA. Along with participation in CENRAP, this partially 

fulfills Minnesota’s requirement under 40 CFR 51.308(i) to coordinate and consult with FLMs on areas 

such as implementation, assessment of visibility impairment, and recommendations regarding the 

reasonable progress goal and strategies for improvement. More specifics on Minnesota’s consultation 

with FLMs are treated in Chapter 4. 

Process 

In 2004 and 2005, a number of discussions were held between state and tribal representatives in the upper 

Midwest concerning air quality planning to address regional haze in the four Class I areas in Michigan 

and Minnesota. This process included several conference calls and a meeting in Madison, Wisconsin held 

on May 24, 2005. 

Formal discussions geared toward specific SIP requirements began in July 2006, when Minnesota met in 

conference call with representatives from North Dakota, Iowa, Wisconsin, Michigan, the Mille Lacs and 

Leech Lake bands of Ojibwe, and FLMs, RPO and EPA representatives. This group determined that 

additional parties should be added to the process and that this group should continue to meet through 

conference calls approximately every three weeks during the development of the regional haze SIPs. 

The first several months of calls focused on developing an agreed-upon technical base of information 

about the visibility conditions in the four Class I areas. This included documenting baseline and natural 

visibility conditions, and determining the chemical constituents of haze and key contributors of visibilityimpairing emissions (geographical and sources and source categories). The shared technical work is 

documented in a technical memo “Regional Haze in the Upper Midwest: Summary of Technical 

Information,” which is attached as Appendix 3.1. 

The consultation group also shared modeling results, discussed visibility improvement expected to result 

from on-the-books controls, and discussed BART and other control strategies. As part of the consultation 

process, LADCO managed a contract where various control strategies were evaluated based on the 

designated four factors; the consultation group provided input to LADCO on each part of the project. The 

control strategies that were evaluated included: on-the-books controls (as a reference point for 
19 

reasonableness under the four factors), various sector level controls, and some facility specific control 

measures. (See Chapter 10 and Appendix 10.5). 

The states involved in the consultation group also collaborated to ensure that a consistent future year 

scenario was used by all states. For example, the states agreed to use version 3.0 of EPA’s Integrated 

Planning Model (IPM) as the basic prediction for EGU emissions in 2018. Further information is 

provided in Chapters 8 and 10. 

In September 2007 the MPCA sent a letter to the states involved in the Northern Class I areas 

consultation process. This letter contained formal notification of the states that Minnesota is listing in this 

SIP as causing or contributing to visibility impairment in VNP and BWCAW. It also contained 

information on Minnesota’s proposed process for setting the Reasonable Progress Goals (RPG) for its 

Class I areas, and asked states and tribes to formally respond with an acknowledgement of their 

participation in the consultation process and their belief that the consultation process could be 

successfully concluded or an indication of what other issues should be discussed. 

Although Minnesota had not yet set the RPGs for VNP and BWCAW when the consultation letter was 

sent out, the MPCA’s letter indicated that additional control measures (beyond on-the-books controls, 

BART, CAIR, and the Northeastern Minnesota plan) were likely to be reasonable for both Minnesota and 

the contributing states. Minnesota committed to evaluating additional control measures and including a 

plan for implementing reasonable controls in the Five Year SIP Assessment. The MPCA requested that 

the five contributing states (Illinois, Iowa, Missouri, North Dakota, and Wisconsin) make the same 

commitment. In particular, Minnesota asked Iowa, Missouri, North Dakota and Wisconsin to evaluate the 

reasonableness of reductions of SO2 from EGUs to reach a statewide rate of 0.25 lbs/MMBtu, and asked 

North Dakota to evaluate NOX emission reductions from EGUs. 

In response, the Missouri DNR indicated that they do not believe they are significant contributors to 

visibility impairment in Minnesota’s Class I areas, and that evaluation of additional controls would not be 

reasonable. Iowa indicated that they cannot commit to controls beyond CAIR, and that the cost in $/ton 

of additional reductions is greater than the cost of complying with CAIR and therefore not cost-effective 

for visibility improvement. North Dakota provided only an informal response, but indicated that a 

lb/MMBtu comparison for EGUs is not reasonable, and that Minnesota should demonstrate that its EGUs 

have spent an equivalent amount (on a $/dv basis) as is being requested from out of state sources. 

A copy of Minnesota’s letter (and the responses received) can be found in Appendix 3.2. More 

information on the RPG and the state responses is in Chapter 10. The MPCA continues to believe that 

our request that the contributing states at least evaluate control measures beyond CAIR, BART and onthe-book controls, report on that evaluation in the Five Year SIP Assessment, and undertake reasonable 

additional controls, is a reasonable request. The MPCA requests that EPA take this into consideration 

when reviewing the SIPs of contributing states. 

All documentation of the Northern Class I areas consultation process can be found on the LADCO/ 

MRPO website.8

 This webpage includes documentation of the minutes from each group conference call, 

including a list of participants, as well as various other documents related to the Northern Class I 

consultation process. These minutes and documents will show the major decisions that the members of 

the Northern Class I consultation process felt were important to discuss and document at the group level. 

 

8

 MRPO, Regional Haze Consultation – Northern Class I areas. 
20 

Chapter 4. State and Federal Land Manager Coordination

Coordination between states and the Federal Land Managers (FLMs) is required by 40 CFR 51.308(i). 

Minnesota’s Class I areas are managed by the National Park Service (VNP) and the U.S. Forest Service 

(BWCAW). FLMs are an integral part of CENRAP’s POG and have membership on standing 

committees, and have therefore contributed to both the technical and non-technical work used in the 

development of this SIP. In addition, opportunities have been provided by CENRAP for FLMs to review 

and comment on each of the technical documents developed by CENRAP and included in this SIP. 

FLMs were also key participants in the Northern Class I consultation calls. Minnesota provided agency 

contacts to the FLMs as required by 40 CFR 51.308(i)(1). 

Consultation During SIP Development 

In development of the SIP, the FLMs were consulted in accordance with the provisions of 40 CFR 

51.308(i)(2). The MPCA provided FLMs an opportunity for consultation, in person and at least 60 days 

prior to holding any public hearing on the implementation plan. 

The MPCA consulted with the FLMs to discuss the land managers’: 

• Assessment of the impairment of visibility in any Class I areas; 

• Recommendations on the development of reasonable progress goals; and 

• Recommendations on the development and implementation of strategies to address visibility 

impairment. 

In addition to discussions on the SIP through the RPO framework, Minnesota and the other states 

involved in consultation about visibility in the four Northern Class I areas included FLMs in the ongoing 

discussions. FLMs were therefore able to give their comments about the technical work and control 

strategies under discussion by the states throughout the period of regional haze SIP development, as well 

as the determination of the reasonable progress goals. The decisions made and documented in the 

Northern Class I calls (see Chapter 3) included FLM input, as can be seen in the minutes and 

documentation of call participants. 

The MPCA also extended invitations to several FLMs to participate in informal stakeholder meetings in 

January and May 2007, and several did take the opportunity to attend those meetings and hear about the 

MPCA’s haze SIP development. 

The MPCA also consulted with the FLMs on BART and the BART strategy for Minnesota as published 

in the State Register (see Appendix 9.2). Consultation between the MPCA and the FLMs continued as 

BART analyses prepared by facilities were made available online and the MPCA began the process of 

BART determinations. 

The MPCA also had direct and extensive consultation with FLMs from the National Park Service and 

Forest Service in developing a strategy to address visibility impairment resulting from emissions from 

new and existing sources in the geographic area of Minnesota in closest proximity to the Class I areas. 

MPCA staff members met in conference calls over the course of several months beginning in the spring 

of 2007 with a small group of FLMs involved with Minnesota’s Class I areas. The FLMs involved 

included: Bruce Polkowsky, Don Shepherd, John Bunyak, David Pohlman, and Chris Holbeck of the 

National Park Service and Trent Wickman of the Forest Service. 

This consultation process resulted in the plan for Northeast Minnesota that is part of Minnesota’s longterm strategy for reducing regional haze (Chapter 10, Appendix 10.4), which will be implemented 

through this SIP and a Memorandum of Understanding between Minnesota and the federal land 
21 

management agencies. The MPCA and the FLMs also worked together to share the plan with 

stakeholders through the early summer of 2007. 

MPCA provided the FLMs with early drafts of portions of this SIP submittal, particularly the portions 

concerning the RPG and long-term strategy. An informal draft of much of the SIP was provided to 

several of the FLMs mentioned previously during a face-to-face meeting between MPCA staff members 

and the FLMs at VNP on September 20 and 21, 2007, and emailed at that time to the Regional Haze 

Coordinators for the Forest Service and Fish and Wildlife Service. The MPCA invited comments on the 

early draft SIP. 

Official Notice and Consultation 

MPCA sent the full draft SIP to the FLMs on February 4, 2008. Minnesota notified the FLMs of all 

stakeholder meetings, and the official public meeting held on April 10, 2008. 

Comments received from the FLMs are included in with the public comments in Appendix 2.4. 

Minnesota considered and incorporated the FLMs comments on the SIP draft as described in the 

Response to Comments documents, also in Appendix 2.4. All FLM comments received prior to the public 

meeting were discussed, along with MPCA’s initial response, at the public meeting. 

As the MPCA worked to respond to FLM comments, such as a request that BART determinations be 

made for EGUs, the MPCA continued to share information with the FLMs. This included draft and 

revised BART determinations for Minnesota’s subject-to-BART EGUs. FLM comments on these BART 

determinations are included in Appendix 2.5, under the heading “Response to Interim Comments on 

Revised Regional Haze SIP.” These comments and the MPCA’s response were included in the public 

notice period of the revised SIP. 

Minnesota will continue to coordinate and consult with the FLMs during the development of future 

progress reports and plan revisions, as well as during the implementation of programs having the potential 

to contribute to visibility impairment in the mandatory Class I areas. 

The plan for Northeast Minnesota and the MPCA’s agreement with the FLMs specifically require 

consultation in order to ensure that the long-term strategy goals are being met. 

The FLMs must continue to be consulted in the following instances: 

• Development and review of implementation plan revisions; 

• Review of 5-year progress reports; and 

• Development and implementation of other programs that may contribute to impairment of 

visibility in Class I areas. 

Coordination and consultation will continue to occur, as needed, through CENRAP and the Northern 

Class I consultation process, and the MPCA will continue to consult with the FLMs directly. 
22 

Chapter 5. Assessment of Visibility Conditions in Class I areas 

Baseline, Natural and Current Conditions 

The goal of the RHR is to restore natural visibility conditions to the 156 Class I areas identified in the 

1977 Clean Air Act Amendments by mitigating all human-caused impairment of visibility. As stated in 

the rule, “natural conditions includes naturally occurring phenomena that reduce visibility as measured in 

terms of light extinction, visual range, contrast, or coloration” (40 CFR 51.301(q)). Regional Haze SIPs 

must contain measures that make “reasonable progress” toward the natural visibility goal by reducing 

anthropogenic emissions that cause haze. For each Class I area, there are three visibility metrics that are 

part of determining reasonable progress: 

• Baseline conditions 

• Natural conditions 

• Current conditions 

Each of the three metrics includes the concentration data of the visibility pollutants as individual terms in 

the light extinction algorithm, with respective extinction coefficients and relative humidity factors. Total 

light extinction when converted to deciviews (dv) is calculated for the average of the 20 percent best and 

20 percent worst visibility days. Most information on visibility data, including calculations of conditions, 

is housed on the web through the Visibility Information Exchange Web System (VIEWS). 

“Baseline” visibility is the starting point for the improvement of visibility conditions. It is the average of 

the Interagency Monitoring of Protected Visual Environments (IMPROVE) monitoring data for 2000 

through 2004 and can be thought of as “current” visibility conditions for this initial period. The 

comparison of initial baseline conditions to natural visibility conditions indicates the amount of 

improvement necessary to attain natural visibility by 2064. If states achieve visibility improvement at a 

constant rate over 60 years, visibility conditions will improve along the glide slope shown in Figure 5.1. 

Figure 5.1: Uniform Rate of Progress (URP) to Achieve Natural Conditions in 60 Years 

Natural visibility is determined by estimating the natural concentrations of visibility impacting pollutants 

and then calculating total light extinction with the light extinction algorithm. Each state must estimate 

natural visibility levels for Class I areas within its borders in consultation with FLMs and other states (40 

CFR 51.308(d)(2)). After the initial baseline (2000 – 2004) period, “current conditions” are to be 

assessed every five years as part of the SIP review where actual progress in reducing visibility impairment 

is compared to the goals set in the SIP. 
23 

Default and refined values for natural visibility conditions 

EPA guidance provides states with a “default” estimate of natural visibility.9

 The default values of 

concentrations of visibility impairing pollutants are based on a 1990 National Acid Precipitation 

Assessment Program report.10 In the guidance, the United States is divided into “East” and “West” along 

the western boundary of the states one tier west of the Mississippi River. This divides the CENRAP 

states between the two areas: “East” which includes Arkansas (AR), Iowa (IA), Louisiana (LA), 

Minnesota (MN), and Missouri (MO) with seven Class I areas, and “West” which includes Kansas (KS), 

Nebraska (NE), Oklahoma (OK), and Texas (TX) with three Class I areas. 

In the guidance, EPA also provides that states may use a “refined approach” to estimate the values that 

characterize the natural visibility conditions of the Class I areas. The purpose of refinement would be to 

provide more accurate estimates with changes to the extinction algorithm that may include concentration 

values; factors to calculate extinction from a measured particular species and particle size; extinction 

coefficients for certain compounds; geographical variation (by altitude) of a fixed value; and/or the 

addition of visibility pollutants. States can choose between the default and refined equations. 

One equation is used to calculate baseline and current conditions of visibility due to haze-causing 

pollutants; using natural concentrations of the same pollutants, the same equation is used to calculate 

natural visibility. 

The original (default) algorithm: 

The new (refined) algorithm: 

 

9 U.S. EPA, 2003a. 

10 Trijonis, 1990. 

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]Carbon Elemental[

]Carbon Organic[

]Nitrate[f(RH)

bext ]Sulfate[f(RH)

)]ppb(NO[.

Rayleigh )specificsite(Scattering

Coarse[. ]Mass

]SaltSea[(RH)f.

]SoilFine[

Elemental[ ]Carbon

Small[. Organic OrganiceargL[.]Carbon ]Carbon

Small[RH)(f. ]NitrateeargL[(RH)f.]Nitrate

Small[RH)(f.b ]SulfateeargL[(RH)f.]Sulfate

ss

s L

ext s L

330 2

60

71

1

10

82 16

42 15

22 84

×+

+

×+

××+

×+

×+

×+ ×+

××+ ××+

××≈ ××+
24 

The New (or refined) IMPROVE equation is nonlinear in sulfate (SO4), nitrate (NO3) and organic mass 

carbon (OMC) concentrations, accounting for the different light scattering efficiency characteristics as a 

function of concentrations for these three species. The total sulfate, nitrate and organic mass are each 

split into two fractions, representing small and large size distributions of those components. New terms 

have been added for Sea Salt (important for coastal areas) and for light absorption by NO2, where NO2

observations are available. (These observations are not available for Minnesota, so this component was 

not used; it is also not included in the original IMPROVE equation.) Site-specific Rayleigh scattering for 

each IMPROVE monitoring site is used in the new equation, as compared to a constant value assumed in 

the original equation. 

The choice between use of the default or the refined equation for calculating the visibility metrics for each 

Class I area is made by the state in which the Class I area is located. According to 40 CFR 51.308(d)(2), 

the state will make the determinations of baseline and natural visibility conditions. It is with these 

calculations and in consultation with other states whose emissions affect visibility in that Class I area (40 

CFR 51.308(d)(1)(iv)) that the state develops a reasonable progress goal for each Class I area. 

 

Because the refined equation better fits the observed light extinction values, Minnesota has used the 

refined IMPROVE equation to calculate visibility metrics and develop its reasonable progress goals. This 

is consistent with the approach taken by surrounding states; the CENRAP states and those participating in 

the Northern Class I area consultation process have also elected to perform their primary visibility 

projections using the new IMPROVE equation. For comparison, calculations based on the old 

IMPROVE equation are shown in Appendix 5.3. 

Using the refined equation, the MPCA has determined that natural visibility conditions for BWCAW are 

best represented by an average of 11.6 deciviews for most impaired days and 3.4 deciviews for the least 

impaired days. Natural visibility conditions for VNP are best represented by 12.2 deciviews for most 

impaired days and 4.3 deciviews for the least impaired days. 

Consultation regarding the visibility metrics 

As mentioned previously, Minnesota consulted with the states that impact BWCAW and VNP on the 

visibility metrics in those Class I areas. The states discussed which equation to use to calculate the 

visibility conditions as well as which values to use for baseline and natural conditions, particularly due to 

some data substitution done on the monitored data, described later. This consultation process is 

documented in Chapter 3. 

Baseline Visibility Conditions 

Baseline conditions represent visibility for the 20% best (B20%) and 20% worst (W20%) visibility days 

for the initial five-year baseline period of the regional haze program. Baseline conditions are calculated 

using IMPROVE monitor data collected during 2000-2004 and are the starting point in 2004 for the 2018 

uniform rate of progress (URP) goal and 2018 visibility projections. 

Baseline conditions were calculated as follows:11

A. Using monitored data, rank baseline visibility for each day with PM10, PM2.5 and speciated PM2.5

measurements within a Class I area.

1. Obtained PM2.5 speciated monitored data from VIEWs with inclusion of missing data from 

MRPO; 

 

11 U.S. EPA, OAQPS. 2007a. 
25 

2. Estimate extinction coefficient for each day using the new IMPROVE equation12 adopted by the 

IMPROVE Steering Committee in December 2005:13

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] 

 + 1.7 * fSS(RH) * [sea salt] 

 + 0.6 * [coarse mass] 

 + Rayleigh scattering (site specific—BOWA1= 11, VOYA2 = 12) 

 + 0.33 * [NO2 (ppb)] 

where: 

bext is calculated total light extinction in inverse megameters 

fS(RH) is the relative humidity adjustment factor for small particles; 

fL(RH) is the relative humidity adjustment factor for large particles; 

fSS(RH) is the relative humidity adjustment factor for sea salt; and 

The apportionment of the total concentration of sulfate compounds into the concentrations of the 

small and large size fractions is accomplished using the following equations: 

[large sulfate] = ([total sulfate]/20μg/m3) * [total sulfate], for [total sulfate] < 20 μg/m3; 

[large sulfate] = [total sulfate], for [total sulfate] ≥ 20 μg/m3; and 

[small sulfate] = [total sulfate] – [large sulfate] 

The same equations above for large sulfate, are also used to apportion total nitrate and total organic 

mass concentrations into the large and small size fractions. 

NO2 is not currently measured at the IMPROVE monitors in Minnesota, so this factor is not included. 

It also is not part of the “old” IMPROVE equation. 

Table 5.1: Monthly fS(RH) and fL(RH) values 14,15

Class I f(RH) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 

BOWA1 

fS(RH) 3.24 2.84 2.99 2.64 2.93 3.21 3.44 3.67 3.80 3.07 3.50 3.49 

fL(RH) 2.50 2.26 2.32 2.09 2.22 2.42 2.57 2.69 2.76 2.37 2.65 2.65 

fSS(RH) 3.74 3.37 3.34 2.92 3.03 3.43 3.68 3.85 3.95 3.44 3.89 3.92 

VOYA2 

fS(RH) 3.16 2.77 2.82 2.59 2.65 3.28 3.25 3.48 3.66 3.02 3.37 3.32 

fL(RH) 2.46 2.22 2.22 2.07 2.09 2.46 2.46 2.59 2.70 2.35 2.58 2.55 

fSS(RH) 3.69 3.31 3.20 2.90 2.89 3.46 3.55 3.71 3.87 3.42 3.83 3.80 

 

12 IMPROVE Steering Committee, January 2006. 13 VIEWS Website, Regional Haze Rule Planning Documents. 

14 VIEWS Website. 

15 Hand and Malm, March 2006. 
26 

3. Convert bext to decivews (dv) using the following equation: 

Haze Index (dv) = 10 ln(bext /10) 

Where: bext and light scattering due to Rayleigh scattering (i.e. the “10” in the denominator) 

are both expressed in inverse megameters (Mm-1). In order to be consistent across all 

Class I areas, the U.S. EPA prescribed that the Rayleigh Scattering in the 

denominator of the conversion of the extinction value to deciviews should always be 

10 instead of using site-specific Rayleigh Scattering values.16

4. Order the deciview values for all days at each Class I area for each of the 5-years of the baseline 

period from worst (highest deciview value) to best (lowest deciview value). 

B. Calculate the average baseline deciview for the 20 percent worst (highest deciview values) and for the 

best (lowest deciview value).

1. Calculate the arithmetic mean deciview value for the 20 percent worst and best visibility values 

for each year; 

2. Average the resulting 5-year mean deciview values reflecting worst visibility for each of the 

years; and 

3. Average the 5-year mean deciview values reflecting best visibility for each of the years. 

BWCAW has a baseline visibility of 6.4 deciviews for the cleanest 20 percent of the sample days and 

19.9 deciviews for the 20 percent worst visibility days. The average visibility for all days across the 

baseline period is 12.3 deciviews. This is based on sampling data collected at the BWCAW IMPROVE 

monitoring site (BOWA1). A five year average (2000 to 2004) was calculated for each value (both best 

and worst) in accordance with 40 CFR 51.308(d)(2). 

Note that the air monitors at BOWA1 had a long-term malfunction from 2002 through 2004, which 

resulted in missing monitoring data for certain chemical species. Data for sulfate and nitrate, the main 

contributors to visibility impairment, were valid for these days, but data for other species was missing. 

Data for BWCAW has therefore been “patched” for the invalid chemical species by using data from the 

VNP IMPROVE monitor (VOYA2) adjusted based on the usual relationship between the concentrations 

of those chemical species between the two monitors when both captured valid data (determined through a 

regression analysis). 

VNP area has baseline visibility of 7.1 deciviews for the cleanest 20 percent of the sample days and 19.5 

deciviews for the 20 percent worst visibility days. The average visibility for all days across the baseline 

period is 12.6 deciviews. This is based on sampling data collected at the VOYA2 IMPROVE monitoring 

site. A five year average (2000 to 2004) was calculated for each value (both best and worst) in 

accordance with 40 CFR 51.308(d)(2). 

For all four Northern Class I areas, and others around the country, several cases arise where days were 

excluded from the calculation of light extinction because some measured components were missing17 and 

therefore the data did not meet EPA’s guidelines for visibility monitoring data.18 The most frequently 

missing components were coarse mass and soil; however, these two species account for a very small 

fraction of light extinction in the Northern Class I areas and, despite the missing components on these 

 

16 U.S. EPA, OAQPS, 2007a. 

17 Donna Kenski of the Midwest RPO brought this issue to the attention of the Northern Class I consultation group 

and did extensive data analysis on this issue. 

18 U.S. EPA, 2003b. 
27 

days, the light extinction from the sum of the measured species exceeds the 80th percentile. Additional 

information on this issue is included in Appendix 5.2. 

Including these days in the baseline calculations has a small but measurable effect on the average 

deciviews for the 20% worst days. Minnesota has decided to include these days in our baseline 

calculations, even though the guidance calls for them to be excluded, because they appear to be largely 

dominated by anthropogenic sulfate and nitrate sources. Because these are the types of poor visibility 

days that need to be targeted by regional haze control strategies they were retained in order to assure that 

they receive adequate scrutiny. 

Natural Visibility Conditions 

Minnesota relied on natural visibility conditions calculated with the new IMPROVE algorithm by the 

VIEWS staff. Errors in the original calculations of natural conditions, impacting sites at high altitude and 

sites with substituted data (such as BWCAW) were found, and Minnesota used corrected natural 

conditions distributed by email from the Cooperative Institute for Research in the Atmosphere (CIRA) in 

August 2007.19 MPCA understands that these data will be posted on the VIEWS website, but they are not 

yet available. Nonetheless, Minnesota has relied on these data as we believe they offer the best picture of 

the natural conditions. The calculation method for natural conditions is provided in “Calculation Method 

for Natural Conditions with the New IMPROVE algorithm,” presented to the Air and Waste Management 

Association specialty conference “Aerosol and Atmospheric Optics: Visual Air Quality and Radiation” in 

Moab, Utah, April 28, 2008 through May 2, 2008. 

Table 5.2, below, gives a summary of the visibility metrics for Minnesota’s Class I areas; these metrics 

include all substituted data and the re-inclusion of the dropped days as described above. The baseline and 

natural condition values in Table 5.2 are those used by the MPCA in developing this SIP and the RPG for 

Minnesota’s Class I areas. 

Table 5.2: Visibility Metrics for Minnesota’s Class I areas20

Natural Background Conditions21

Class I area Average for 20% 

Worst Days (dv) 

Natural Conditions for 

20% Best Days (dv) 

Average for 20% Worst 

Days Bext (Mm-1) 

Average for 20% Best 

Days Bext (Mm-1) 

BWCAW 11.6 3.4 33 14 

VNP 12.1 4.3 35 15 

Baseline Visibility Conditions 2000-2004 

Class I area Average for 20% 

Worst Days (dv) 

Average for 20% Best 

Days (dv) 

Average for 20% Worst 

Days Bext (Mm-1) 

Average for 20% Best 

Days Bext (Mm-1) 

BWCAW 19.9 6.4 76.0 19.2 

VNP 19.5 7.1 72.5 20.5 

 

19 Copeland, 2007. (Email) 

20 This table shows the official visibility conditions used by the MPCA in developing this SIP. It includes all 

substituted data for BWCAW and the re-inclusion of all sample days that were previously dropped. Note that some 

days that were previously dropped did not include measurements for all components, therefore Bext cannot be 

calculated for those days. The Bext values in the table, then, are an average of only those in the 20% best or worst 

where light extinction can be calculated. 

21 Natural background conditions were not recalculated with the inclusion of the previously dropped days, due to the 

time necessary to do these calculations and the belief that the resulting change would be very small. 
28 

Table 5.3 shows the yearly visibility metrics for all four Northern Class I areas, with the same algorithm 

and data adjustments as made for Table 5.2. Table 5.3 calculates the URP for all four Northern Class I 

areas with the adjusted data. 

Table 5.3: Adjusted Visibility Metrics in dv for Northern Class I areas

 2000 2001 2002 2003 2004 Baseline 

(Average) 

Natural 

Conditions 

BWCAW 

20% Worst 20.2 20.2 20.8 20.1 18.2 19.9 11.6 

20% Best 6.0 6.9 6.9 6.5 5.8 6.4 3.4 

VNP 

20% Worst 19.6 18.6 20.1 20.3 18.9 19.5 12.1 

20% Best 7.0 7.0 7.5 7.6 6.3 7.1 4.3 

Isle 

Royale 

20% Worst 20.5 23.1 22.0 22.3 20.0 21.6 12.5 

20% Best 6.5 7.1 7.0 7.1 6.1 6.8 3.7 

Seney 

20% Worst 22.9 25.9 25.4 24.5 23.2 24.4 12.8 

20% Best 6.6 6.8 7.8 8.0 6.6 7.2 3.7 

As this table shows, visibility conditions in Minnesota’s Class I areas have been relatively consistent over 

the baseline period. Preliminary indications are that this trend has continued. Although not used in 

calculating the baseline, in 2005 the average conditions at BWCAW for the 20% worst days was 21.3 dv 

and for the 20% best days was 6.3 dv. For VNP, it appears that the average condition for 20% worst days 

in 2005 was 20.3 dv and for the 20% best days the average conditions were 6.8 dv. 

Table 5.4 lays out the URP that would result in Minnesota’s Class I areas meeting natural conditions by 

2064 and shows the deciview improvement needed to meet natural conditions for both best and worst 

20% days and to meet the URP glide path for 20% worst days in 2018. 

Table 5.4: Northern Class I areas URP in dv; Adjusted Data 

Annual 

URP 

(W20%) 

2018 URP 

Goal 

(W20%) 

Improvement from 

Baseline URP 

Requires by 2018 

(W20%) 

Improvement from 

Baseline to Meet Natural 

Conditions 

(W20%) 

Improvement from 

Baseline to Meet 

Natural Conditions 

(B20%) 

BWCAW 0.14 17.9 2.0 8.3 3.0 

VNP 0.12 17.8 1.7 7.3 2.8 

Isle Royale 0.15 19.5 2.1 9.1 3.1 

Seney 0.19 21.7 2.7 11.6 3.5 

Figures 5.2 and 5.3 graphically show the URP for VNP and BWCAW, respectively. Baseline conditions 

shown include the visibility conditions for each individual year of the baseline period, designated with the 

smaller points; the URP line is drawn from the average over the baseline period for both best and worst 

days. The graphs also visually show both the improvement that would be needed to meet natural 

conditions on the 20% best days as well as the requirement for no degradation on the 20% best days. 
29 

Figure 5.2: Uniform Rate of Progress for BWCAW 

Figure 5.3: Uniform Rate of Progress for VNP

0.0

5.0

10.0

15.0

20.0

25.0

1990 2000 2010 2020 2030 2040 2050 2060 2070

Year

Deciviews

Baseline Conditions

20% Worst Days

Baseline Conditions

20% Best Days

Natural Conditions 

20% Worst Days

No Degradation on 

20% Best Days

Natural Conditions 

20% Best Days

2018 URP: 17.9 

0

5

10

15

20

25

1990 2000 2010 2020 2030 2040 2050 2060 2070

Year

Deciviews

Baseline Conditions

20% Worst Days

Baseline Conditions

20% Best Days

2018 URP: 17.8 

Natural Conditions 

20% Best Days

No Degradation on 

20% Best Days

Natural Conditions 

20% Worst Days 
30 

Updated Visibility Conditions 

Since 2004, additional data on visibility conditions in the Class I areas has become available. Table 5.5, 

below, shows visibility conditions from 2005 through 2007 at the Class I areas impacted by Minnesota 

(BWCAW, VNP, and Isle Royale). Data from 2005 through 2007 was taken from the VIEWS Regional 

Haze Rule dataset, posted on the VIEWS webpage. The baseline conditions from 2000 through 2004, an 

average since 2000, and natural conditions are included for reference.22

Table 5.5: Visibility Conditions 2005 - 2007 

 

22 Note that the 2005 through 2007 data has not been adjusted. The data has not been checked for days were 

excluded from the calculation of light extinction because some measured components were missing but where the 

light extinction from measured species exceeds the 80th percentile. Therefore, data may not be directly comparable 

to the 2000 – 2004 average, but should still provide a snapshot of visibility trends in the Class I areas impacted by 

Minnesota. 

Site Days 2005 2006 2007 

Baseline 

(Average 

2000 - 2004) 

2000 - 2007 

Average 

Most Recent Five 

Year Average 

(2003 - 2007) 

Natural 

Conditions 

BWCAW 20% Worst 21.3 19.6 19.8 19.9 20.0 19.8 11.6 

20% Best 6.3 5.8. 5.8 6.4 6.3 6.1 3.4 

VNP 20% Worst 19.9 20.5 19.2 19.5 19.6 19.8 12.1 

20% Best 6.8 6.5 6.7 7.1 6.9 6.8 4.3 

Isle 

Royale 20% Worst 23.8 21.9 21.7 21.6 21.9 21.9 12.5 

20% Best 7.1 6.4 6.4 6.8 6.7 6.6 3.7 
31 

Chapter 6. Monitoring Strategy 

Part 40 CFR 51.308(d)(4) of the federal Regional Haze Rule requires a monitoring strategy for 

measuring, characterizing, and reporting regional haze visibility impairment that is representative of all 

mandatory Class I areas within Minnesota. The monitoring strategy relies upon participation in the 

IMPROVE network. 

Minnesota’s participation in the IMPROVE monitoring network largely meets the requirements of 

subsections (i) and (iv). The IMPROVE network began in 1988 with 42 sites at or near Class I areas. At 

the time of promulgation of the Regional Haze Rule in 1999, there were 80 monitors. In 2000 and 2001, 

an additional 30 sites were added to Class I areas, and 34 to non-Class I areas. (IMPROVE monitors 

operated outside of Class I areas are “Protocol” monitors, operated for FLMs, states, and tribes). Another 

18 IMPROVE Protocol monitors were added in 2002, 13 of which went into CENRAP state and Tribal 

lands. Today there are 110 Class I area IMPROVE monitors and 52 non-Class I area (IMPROVE 

Protocol) monitors in the country. 

In the language of subsection (i), these additional monitors were established in order to measure visibility 

pollutants in areas outside of national parks and wilderness areas, to understand the concentrations, 

sources and transport of regional haze that affects the Class I areas. Subject to continued EPA funding, 

these same monitors will be used to assess progress in attaining the reasonable progress goals in 

subsequent SIP reviews and revisions. 

Current Monitoring Strategy 

Upon the creation of CENRAP, the Monitoring Workgroup identified large visibility data voids for 

Southern Arkansas, Iowa, Kansas, Southern Minnesota, Nebraska, and Oklahoma. Only five IMPROVE 

sites were located in the CENRAP region. Between 2000 and 2003, five more IMPROVE sites and 15 

IMPROVE Protocol Sites were installed. 

In Minnesota, IMPROVE sites are located in the two Class I areas, at BWCAW (monitor BOWA1) and 

VNP (monitor VOYA2). IMPROVE Protocol sites are located in the southern areas of the state, in Blue 

Mounds and Great River Bluffs. Minnesota commits to meeting the requirements under 40 CFR 

51.308(d)(4)(iv) to report to EPA visibility data for each of Minnesota’s Class I areas annually. 

The filter samples from the IMPROVE modules are sent for analysis to the Crocker Nuclear Laboratory 

of the University of California in Davis and the analysis data is posted to the IMPROVE website and the 

VIEWS website. This fulfills Minnesota’s requirement for electronic reporting of visibility data under 

subsection (iv). 
32 

Figure 6.1 CENRAP IMPROVE and IMPROVE Protocol Sites 

In addition to the four IMPROVE sites, Minnesota also has several monitoring stations for fine and coarse 

particulate matter located across the state, which can be used to gather additional information about the 

concentrations, sources, and transport of particulate matter. For fine particulate matter, the MPCA has 

three monitoring networks: Federal Reference Method (FRM), continuous, and speciation networks. 

There are currently 29 PM2.5 sites in Minnesota operating as part of one of these networks. The speciation 

network, used to gather data on the species composition of fine particulate matter, includes the four 

IMPROVE monitors and two additional Speciation Trends Network (STN) sites operated by the MPCA, 

in Minneapolis and Rochester.23

The location of these monitors, for those active as of January 2008, is shown in the tables below: 

Table 6.1: Active Minnesota PM2.5 Monitoring Sites 

Site Name City County

Dlth Lincoln Park Sch Duluth St. Louis 

WDSE Duluth St. Louis 

37W/I35 Duluth St. Louis 

Virginia Virginia St. Louis 

Ely Fall Lake Lake 

Detroit Lakes Detroit Becker 

Brainerd Airport Oak Lawn Crow Wing

Fond Du Lac Cloquet Carlton 

Mille Lacs Kathio Mille Lacs

St. Cloud Talahi Sch St. Cloud Stearns 

St. Michael School St. Michael Wright 

Anoka Airport Blaine Anoka 

 

23 MPCA, 2008. 
33 

Site Name City County

Wenonah School Minneapolis Hennepin 

MSP Airport Fort Snelling Hennepin 

Putnam School Minneapolis Hennepin 

Phillips Minneapolis Hennepin 

Richfield Richfield Hennepin 

NE Fire Station Minneapolis Hennepin 

Humboldt Minneapolis Hennepin 

St. Louis Park St. Louis Park Hennepin 

Harding HS St. Paul Ramsey 

St. Paul Hlth Dept St. Paul Ramsey 

Red Rock Road St. Paul Ramsey 

Apple Valley Apple Valley Dakota 

Shakopee Shakopee Scott 

Marshall Airport Fairview Lyon 

ROCHESTER Rochester Olmsted 

Table 6.2: Active Minnesota PM10 Monitoring Sites 

Site Name City County

Dlth Lincoln Park Sch Duluth St. Louis 

WDSE Duluth St. Louis 

37W/I35 Duluth St. Louis 

Virginia Virginia St. Louis 

DM&IR Cemetery Two Harbors Lake 

Mille Lacs Kathio Mille Lacs 

St. Cloud Talahi Sch St. Cloud Stearns 

St. Michael School St. Michael Wright 

St. Paul Park 3 St. Paul Park Washington 

Mpls downtown Minneapolis Hennepin 

Humboldt Minneapolis Hennepin 

St. Louis Park St. Louis Park Hennepin 

Harding HS St. Paul Ramsey 

St. Paul Hlth Dept St. Paul Ramsey 

Red Rock Road St. Paul Ramsey 

Ross Av/St Paul Fire St. Paul Ramsey 

Vandalia St. Paul Ramsey 

Apple Valley Apple Valley Dakota 

Wicker Rosemount Dakota 

MPCA Rosemount Dakota 

ROCHESTER Rochester Olmsted 

Future Monitoring Strategy 

In order to assess progress in reducing visibility impairment in Class I areas, the existing IMPROVE and 

IMPROVE Protocol sites should be maintained. Operation is contingent upon continued federal funding 

to measure, characterize and report regional haze visibility impairment. 

The MPCA believes that maintenance of the IMPROVE monitoring network is critical to the long-term 

success of the Regional Haze program. In the event of a complete loss of federal funding, the MPCA will 

attempt to provide support for the operation of at least one of the two IMPROVE sites. 
34 

Should the IMPROVE monitoring network be disbanded, Minnesota could use information from other 

PM2.5 monitoring sites to make some estimates of PM2.5 concentrations, and thus visibility impairment, in 

the Class I areas. Minnesota evaluates the monitoring network periodically, including evaluation of 

technology changes and the need for new monitors. More information about the monitoring networks in 

place in Minnesota, and any future planned changes, can be found in the Annual Air Monitoring Network 

Plan for the State of Minnesota.24 Further details regarding Minnesota’s ambient air monitors (location, 

date of installation etc.) and monitoring data can also be found online through the MPCA’s 

Environmental Data Access System.25

Special Monitoring Studies 

As funding permits, CENRAP, in cooperation with states and tribes, intends to study the impact of 

ammonia and carbon on visibility impairment in the CENRAP region. Preliminary monitoring studies 

and monitoring data analysis suggests that these two air constituents contribute to a large portion of 

visibility impairment in the CENRAP geographical area. 

 

24 MPCA, 2008. 

25 MPCA, Environmental Data Access System - Air Quality Data. (webpage) 
35 

Chapter 7. Emission Inventory

40 CFR 51.308(d)(4)(v) requires a statewide emission inventory of pollutants that are reasonably 

anticipated to cause or contribute to visibility impairment in any mandatory Class I area. As specified in 

the applicable EPA guidance, the pollutants inventoried by Minnesota include volatile organic 

compounds (VOC), nitrogen oxides (NOX), fine particulate (PM2.5), coarse particulate (PM10), ammonia 

(NH3), and sulfur dioxide (SO2). 

Minnesota rules require point sources to submit reports of their emissions to the MPCA each year, and an 

annual point source emission inventory is produced. Minnesota compiles a full statewide emission 

inventory every three years, and submits this data to the National Emission Inventory (NEI). Minnesota 

will continue to update the full emission inventory on this three-year cycle.

State Inventory – 2002 

The MPCA’s most recent complete statewide emission inventory is from 2002. A summary of the 

inventory results is shown below in Table 7.1. 

Table 7.1: Minnesota 2002 Baseline Emissions Inventory Summary (tpy)26

VOC NOX SO2 PM10 PM2.5 NH3

Point Sources 29,000 150,000 130,000 31,000 13,000 1,300 

Area Sources 160,000 57,000 17,000 730,000 150,000 170,000 

Mobile Sources 

On-Road 91,000 170,000 3,000 3,800 2,800 5,400 

Non-Road 84,000 100,000 9,100 9,700 8,900 97 

TOTAL 366,000 485,000 160,000 779,000 169,000 179,000 

Because the 2002 emission inventory is critical as a baseline for comparing future emissions and 

application of control strategies, MPCA felt it was important to understand if 2002 was a representative 

year, or if the emissions tended to be high or low when compared to other recent years. If 2002 emissions 

were high, for example, future year emissions might show decreases that might be wrongly attributed to 

the implementation of control strategies. 

 In order to gain a more complete understanding of the 2002 inventory, MPCA staff compared point 

source emissions in the 2002 inventory to point source emissions from surrounding years. In general, 

although there is certainly some variation, the 2002 inventory was found to be largely representative of 

annual emissions from large point sources, particularly for the key haze causing pollutants of SO2 and 

NOX.

27 

MPCA’s emission inventory staff has recently completed compiling the 2005 emission inventory. 

 

26 The emission inventory is presented to two significant digits. Totals might not add due to rounding. 

27 Information on Minnesota’s emission inventory is available in the air quality section of the MPCA’s 

Environmental Data Access system. 
36 

The 2005 inventory figures are shown in the table below. 

Table 7.2: Minnesota 2005 Emissions Summary (tpy) 

VOC NOX SO2 PM10 PM2.5 NH3

Point Sources 26,000 150,000 130,000 30,000 13,000 2,000 

Area Sources 130,000 34,000 17,000 740,000 140,000 170,000 

Mobile Sources 

On-Road 93,000 140,000 2,600 3,500 2,400 5,700 

Non-Road 96,000 100,000 9,600 8,400 8,000 64 

TOTAL 349,000 422,000 159,000 778,000 166,000 180,000 

Inventory Methodology 

The MPCA EI staff compiled the 2002 Minnesota Point Source Inventory using acceptable, established 

methodologies, which are ranked by preference. This hierarchy of methodologies and use are required by 

Minnesota’s Air Emission Inventory Rule, Minn. R. 7019.3000, for facilities submitting an air emission 

inventory. All air permit holders are required to submit an annual air emission inventory. 

The following are the accepted methodologies in order of preference: 

1) Continuous Emission Monitor (CEM) Data 

2) Performance Test Data 

3) Volatile Organic Compound (VOC) or Sulfur Dioxide (SO2) Mass Balance 

4) Emission Factors – EPA published generic factors from documents such as AP-42 or FIRE 

database. 

Methodologies that can reflect site and process specific data are always preferable to a default, generic 

emission factor. AP-42 emission factors represent averaged emission factors for the entire industry or 

type of equipment. Appendix 7.1 contains additional information on how Minnesota compiles its 

emissions inventory. 

Modeling Inventory 

Although the statewide inventory forms the basis of the emissions that are input into the atmospheric 

chemistry and transport models that ultimately predict visibility conditions, substantial work is needed to 

process the emissions for modeling purposes. Therefore, the specifics of the emissions used in the 

modeling work, known as the modeling inventory, are detailed in Chapter 8. 
37 

Chapter 8. Modeling

The Regional Haze rule requires states to “establish goals (expressed in deciviews) that provide for 

reasonable progress toward achieving natural visibility conditions for each Class I area within a state,” 

improving visibility on the most impaired days and not degrading visibility on the least impaired days.28 

The core of the visibility assessment – the baseline and natural conditions based on observed data – is 

fully described in Chapter 5. 

The baseline conditions are developed from five years of monitoring data, and represent the starting point 

from which reasonable progress is measured. The Regional Haze Rule prescribes the baseline period as 

the years 2000-2004, and defines baseline visibility conditions as the average of the most visibility 

impaired days (the 20 percent worst days), and the average of the least visibility impaired days (the 20 

percent best days) calculated from the monitoring data for each year of the baseline, and then averaged 

over the 5-year baseline period.29 The ultimate goal is to reach natural visibility conditions in 2064, and 

reasonable progress goals are interim goals representing progress toward that end. The year 2018 is the 

initial year for developing a reasonable progress goal. 

Models are used to establish a reasonable progress goal (RPG) by simulating the future visibility 

conditions that will result from future emission estimates. A set of EPA developed guidelines30 outline 

the methodology for modeling future conditions and applying modeled results to develop reasonable 

progress goals. 

Emissions from a “base,” or known, year (i.e. 2002) representing the baseline period and from a year in 

the future (i.e. 2018) are each modeled. The model results are used to estimate the air concentration 

change from base year to future year. These air concentration changes are in the form of ratios of the 

future year air concentrations to the base year concentrations predicted near a monitor location and 

averaged over the same 20 percent worst and 20 percent best days in the base year that were used to 

establish baseline visibility conditions. A ratio is developed for each specie comprising PM2.5 (sulfate, 

nitrate, organic carbon, elemental carbon, fine soil [≤2.5 μm diameter], and coarse particulate matter 

[>2.5 μm, but ≤10 μm diameter]). The ratio is called a Relative Response Factor (RRF), calculated as 

follows: 

RRF[SO4] = Modeled Future Mean [SO4] /Modeled Base Year Mean [SO4]

Where: RRF is the relative response factor (unitless); 

 Future Mean and Base Year Mean are the modeled base year (2002) and the future year 

(2018) concentrations at the Class I area monitor location averaged for the 20 percent 

worst days (and 20 percent best days) as determined by the base year (2002) monitor 

data; and 

The same equation above for sulfate is also used for nitrate, organic carbon, elemental 

carbon, fine soil and coarse particulate matter. 

 

28 40 CFR 51.308(d)(1). 

29 40 CFR 51.308(d)(2). 

30 U.S.EPA, OAQPS, 2007a 
38 

Applying the RRFs to baseline monitoring conditions, for each species comprising PM2.5, provides the 

estimate of future visibility conditions (described below): 

• Multiply each species specific RRF, developed from the 2002 and 2018 modeling data, by the 

corresponding measured species concentration for all of the 20 percent worst (and 20 percent 

best) days over the 5-year baseline period. (example for sulfate below); 

[SO4]future = RRF(SO4) * [SO4]baseline (daily value) 

• Estimate extinction coefficient for each of the 20 percent worst (and 20 percent best) days 

using the IMPROVE equation (detailed in Chapter 5, Baseline Visibility Conditions, 

calculations, Section A.2.), and convert to deciviews (detailed in Chapter 5, Baseline 

Visibility Conditions, calculations, section A.3); and 

• Calculate the average future year deciview for the 20 percent worst (and 20 percent best) 

days. 

1. Calculate the arithmetic mean deciview value for the 20 percent worst and best 

visibility values for each year in the baseline period; and 

2. Average the resulting 5-year mean deciview values (for the 20 percent worst, and for 

the 20 percent best). 

Recognizing the intense resources required to conduct modeling analyses of this nature, EPA guidelines 

for regional haze do not suggest modeling the multiple years comprising the 5-year baseline period, but 

discuss modeling one full year as a “logical goal”. The methodology in the EPA guidelines attempts to 

take into account the year-to-year variability of the meteorology in the monitored baseline. The middle 

year (2002) will have more weight due to the fact that the 2002 emissions and meteorology are used in the 

modeling to develop the RRF applied to the baseline conditions. This application of the model results is 

intended to balance the resource limitations of conducting multiple years of modeling, and to “help reduce 

the impact of possible over-or under-estimations by the dispersion model due to emissions, meteorology, 

or general selection of other model input parameters”. 

The resource requirements for conducting regional scale modeling make it necessary to consolidate 

resources and develop the modeling analyses through the RPO process. Regional haze modeling at 

BWCAW and VNP was performed by CENRAP, MRPO and by Minnesota; MRPO conducted modeling 

using both a 2002 base year and 2005 base year. Minnesota supplemented the RPO modeling by focusing 

on the two Minnesota Class I areas and the visibility impacts of nearby point sources located within 

Minnesota. Minnesota’s modeling uses MRPO-developed emissions and meteorological data inputs from 

the 2002 base year and 2018 future year, with some modifications, and is referred to throughout this 

chapter as the Minnesota(MRPO) case. 

The reasonable progress goals for BWCAW and VNP are set using the Minnesota(MRPO) case; however, 

the other analyses are valuable for assessing uncertainty in the modeling analysis and helping to 

determine whether the model likely overpredicts, underpredicts, or accurately predicts the reasonable 

progress goal associated with the long-term strategy. As part of the weight-of-evidence supporting the 

Minnesota RPG, the end of this chapter contains a summary of differences in the modeling results by 

CENRAP, MRPO (2002) and MRPO (2005) as compared to the Minnesota(MRPO) case. 

The modeling described herein supports the policy decisions made in this Regional Haze SIP. Details on 

the modeling analyses conducted are in a separate document titled “Minnesota Technical Support 

Document for the Regional Haze State Implementation Plan” (TSD). This document is available at 
39 

http://www.pca.state.mn.us/publications/rhsip-tsd.pdf. The sections below summarize the methods and 

inputs used for the regional modeling. 

The Modeling System 

The modeling system is composed of an atmospheric transport and chemistry model, also known as the 

“air quality model,” an emissions model and a meteorological model. The emissions and meteorology 

models create inputs for use by the air quality model. 

One of the criteria considered when choosing a system was its ability to allow Minnesota to conduct 

modeling to assess visibility impacts from Minnesota sources near the Class I area, as this type of 

modeling falls outside the scope of RPO modeling work, which focuses on the larger, more regional 

visibility impacts. The MRPO supports contributing states in conducting modeling and uses an air quality 

model whose resource requirements are reasonable for Minnesota. For this reason, Minnesota chose to 

use the modeling system chosen by MRPO. The modeling system31,

32 is made up of the following: 

• Air Quality Model: Comprehensive Air Quality Model (CAMx). CAMx simulates atmospheric 

and surface processes affecting the transport, chemical transformation and deposition of air 

pollutants and their precursors. Some advantages of CAMx are two-way nesting, which “allows 

CAMx to be run with coarse grid spacing over a wide regional domain in which high spatial 

resolution is not particularly needed, while within the same run, applying fine grid nests in 

specific areas where high resolution is needed”,33 a subgrid scale plume-in-grid module to treat 

the early dispersion and chemistry of point source plumes, a fast chemistry solver increasing 

processing speed allowing overall timely model results, and Particulate Source Apportionment 

Technology (PSAT) that tracks the original source of particulate species by geographic region 

and source category. CAMx is an Eulerian model that computes a numerical solution on a fixed 

grid. Minnesota used CAMx version 4.42. 

• Meteorological Model: The Pennsylvania State University/National Center for Atmospheric 

Research (PSU/NCAR) Mesoscale Meteorological Model (MM5). The MM5 model simulates 

mesoscale and regional scale atmospheric circulation.34 MM5 output data is used in the 

emissions model and in the air quality model. 

• Emissions Model: Emissions Modeling System (EMS-2003). EMS-2003 generates hourly 

speciated emissions on a gridded basis for mobile, nonroad, area, point, natural (biogenic) and 

fires. The emissions are input to an air quality model. 

Model Year Chosen 

Regional haze issues appear throughout the year in the Minnesota Class I areas, which made it necessary 

to model a full year rather than a shorter episode period. A model year must coincide with a year 

scheduled for emissions inventory development. As noted in Chapter 7, states develop full emissions 

inventories every three years, the most recent being the fully completed 2002 inventory. The 2005 

inventory was still in development during the SIP modeling process. EPA guidance suggests choosing a 

model year that has monitoring data available that straddles the model year. Minnesota has selected 2002 

as the base year for modeling. 

 

31 The MRPO conducted modeling for a 2005 base year analysis using CAMx version 4.50, a combination of EMS2003 and Concept (for mobile source), and MM5 run by Alpine Geophysics. 

32 CENRAP chose the Community Multiscale Air Quality Model (CMAQ) as its air quality model, the Sparse 

Matrix Operator Kernel Emissions (SMOKE) model as its emissions model, and MM5 as its meteorological model. 

33 ENVIRON, 2006. 

34 MM5 Community Model Homepage. 
40 

During the iterative process of regional scale modeling, MRPO decided to switch to a 2005 base year. 

Although Minnesota still uses MRPO inputs in its Minnesota(MRPO) model analyses, they remain the 2002 

base year, with some adjustments. The 2002 base year allows Minnesota to better correlate results with 

CENRAP, which also uses 2002 as its base year, and allows for using monitoring data that straddles the 

inventory year (2000-2004) to establish baseline conditions. The state of Iowa developed the 

meteorological data inputs for the 2002 base year.35

Conceptual Description 

As described above, visibility is a year-round issue in the upper Midwest Class I areas. Observed values 

indicate that the 20 percent worst days are spread across all months of the year except February in 2002 

(see Appendix 5.2). During the warmer months several days are influenced by wildfires,36 which can 

contribute large amounts of organic carbon that significantly affect extinction. Wildfire emissions are 

uncontrollable. Natural (biogenic) emissions are another uncontrollable source that impact visibility, i.e. 

volatile organic compounds (VOC) from trees that form secondary organic aerosols. 

Throughout the year, but especially in the warmer months, the controllable emissions of sulfur dioxide 

(SO2) and nitrogen oxides (NOX ) have the most impact on visibility at BWCAW and VNP. These 

emissions are controllable because their release results from human activities. SO2 emissions impact 

visibility year-round, while NOX emissions contribute the most impact on visibility in the colder months. 

This happens because nitrate formation occurs in the colder months, as in the warmer months NOX will 

remain in the gas phase as nitric acid. Ammonia preferentially reacts with SO2, so nitrate forms only 

when there is enough ammonia left over after forming ammonium sulfate by reacting with SO2. While 

particulate sulfate can form whether there is ammonia present or not, particulate nitrate needs ammonia 

to form. 

 

Ammonia is released primarily from animal farms throughout the year, peaking in the warmer months, 

and additionally from agricultural practices in the Spring and Fall. Ammonia is critical to formation of 

ammonium sulfate and ammonium nitrate, the main controllable species contributing to visibility issues 

in the Class I areas. Ammonium nitrate and ammonium sulfate need time to form in the atmosphere and 

are understood to travel large distances 

Modeling/Analysis Protocol 

A protocol details and formalizes the procedures for conducting all phases of the modeling study, 

including the methodology (grid projections, domains, meteorological inputs, emissions inputs, the 

configuration of the model), the evaluation of model performance against observed data, and how the 

visibility analysis will be conducted. Minnesota did not prepare its own regional modeling protocol, 

relying instead on the meteorological and air quality modeling protocols prepared by the MRPO. 

Minnesota explored answers to questions specific to Minnesota beyond the scope covered by the air 

quality modeling protocol prepared by the MRPO. For example, Minnesota is interested in the visibility 

impact of sources located near BWCAW and VNP. This resulted in a modeling analysis using a 12km 

nested grid and a plume-in-grid tool for individual elevated point sources located within a certain distance 

of the Class I areas. Plume-in-grid tracks individual plume segments from each point source, rather than 

immediately dispersing the individual point sources emissions into the grid cell. Therefore, it can treat 

the early dispersion and chemistry of point source plumes. In order to use the plume-in-grid module 

properly, some modifications to the air quality modeling input files were required. For example, stack 

parameter and location information has greater importance when plume-in-grid is employed. The TSD 

provides the protocol for implementing features not covered in the MRPO protocol. 

 

35 Both Minnesota (MRPO) and CENRAP used the same meteorological data inputs developed by the state of Iowa for 

2002. 

36 MRPO, 2007b. 
41 

Emissions Preparations & Results 

Emissions were combined into sectors based on the similarity of the techniques used to process the 

emissions. Sectors are: 

• Point or industrial sources that are identified by locational coordinate and stack parameters (i.e. 

facilities with state permits); 

• Mobile Onroad or automobile and truck traffic on paved roadways; 

• Nonroad or mobile equipment not traveling on roadways (i.e. recreational vehicles, construction 

and agricultural equipment); 

• Marine vessels, airplanes and locomotives (also considered “nonroad” sources although 

techniques vary); 

• Area or stationary sources that are not identified by locational coordinate and stack parameters 

(e.g. agricultural processes like fertilizer use and livestock operations, residential heating); and 

• Biogenic or natural emissions (i.e. trees are an important biological emissions source). 

 

Emissions modeled for regional haze are sulfur dioxide (SO2), nitrogen oxides (NOx), Volatile Organic 

Compounds (VOC), ammonia (NH3), fine particulate (PM2.5) and coarse particulate mass. 

The Base Year Inventory – 2002 

For the most part, base year inventories are developed by each individual state. These are essentially the 

same inventories states submit to the EPA for the National Emissions Inventory (NEI). For some sectors, 

methods initially available to states for inventory development were inadequate for air quality modeling. 

For these sectors, the RPOs have independently, and in some cases cooperatively, hired contractors to 

develop emissions data to support improvement of state-developed inventories where the other 

methodology, insufficient for modeling purposes, was used. For example, it is important to have accurate 

ammonia emissions because ammonia combines with sulfuric and nitric acid to form aerosol sulfate and 

nitrate, significant components of PM2.5 and of visibility impairment. Also, states do not create 

inventories for biogenic sources, so these inventories had to be created for modeling purposes. 

Although an inter-RPO technical consultation mechanism was in place, the timing of individual RPO 

inventory improvements results in some variation in the emissions characterization of a state among the 

RPO in which it is a member, and other RPOs. Minnesota worked closely with both CENRAP and 

MRPO to ensure Minnesota’s sources were characterized as accurately and with as much scrutiny as 

possible; the two RPOs independently developed a modeling inventory for Minnesota. In the TSD, 

Minnesota summarizes overall differences between the CENRAP and MRPO inventories and how these 

differences might impact the model results. 

The Future Year Inventory – 2018 

The Economic Growth Analysis System (EGAS) model was used to estimate the growth of emissions 

from 2002 to 2018 for all source categories, except on-road mobile sources and EGUs. EGAS is a 

forecast model based on the premise that growth in emissions largely depends on the growth in economic 

activity, particularly changes in sales forecasts, in an area. On-road mobile sources were grown with 

MOBILE6. EGU emissions were grown using the Integrated Planning Model (IPM). IPM predicts future 

EGU emissions assuming an energy balance throughout electricity supply grids. 

The RPOs agreed to use IPM to predict future EGU emissions during the technical consultation process. 

The consulting firm ICF International developed the IPM model, which EPA uses to evaluate the future 

impact of policies and regulations, in combination with projected energy needs, on EGUs. For example, 

EPA used IPM to develop the Clean Air Interstate Rule (CAIR). The IPM model output presumes CAIR 

is implemented. The modeling that supports Minnesota’s reasonable progress goals incorporated IPM 

version 3.0. 
42 

The MPCA believes IPM 3.0 predictions for Minnesota in 2018 are much improved over previous 

versions of IPM simulations. Other RPOs, such as CENRAP, use an earlier IPM version 

2.1.9(VISTAS).37 Upon review of the IPM 3.0 predictions, MPCA staff found some adjustments to the 

output were necessary to reflect staff knowledge of Minnesota EGUs and future projections, but many 

more adjustments would be needed to IPM 2.1.9(VISTAS). Both versions of IPM presume CAIR is 

implemented, but they make different assumptions in other areas, such as fuel cost estimates. 

The MRPO modified the IPM 3.0 future year estimates with information submitted by its member states 

plus Minnesota, North Dakota, Iowa and Missouri. For example, Minnesota made a correction to the 

emissions for Minnesota Power-Boswell to account for an underestimation of the facility’s capacity in 

IPM. Further adjustments were limited to committed control projects that occurred after the deadline for 

submission of such projects to EPA for inclusion in IPM 3.0. All corrections and adjustments made to 

Minnesota EGUs were done in consultation with industry representatives. Table 8.1 summarizes 

Minnesota’s adjustments and corrections to IPM 3.0. 

Table 8.1: Minnesota Adjustments and Corrections to IPM Version 3.0 

Facility Name Basis for Correction/Adjustment Unit # IPM base

Total Emissions 

(Mton) 

IPM “will do”

Total Emissions 

(Mton) 

NOx SO2 NOx SO2

Minnesota 

Power-Boswell 

Unit 3 adjusted to reflect NOX permit 

limit, SO2 decreased with addition of 

Fabric Filter/Flue Gas Desulfurization 

Unit 4 capacity increased from 425 

MW to 535 MW 

3 

4 

0.79 

3.75 

6.11 

4.00 

0.93 

4.72 

1.19 

3.22 

Xcel - A.S. King Adjusted based on permit limit. 1 1.43 1.87 2.08 2.49 

Xcel - Black 

Dog 

Adjusted upward based on current 

performance in response to Xcel 

Energy comments. 

3 

4 

1.17 

1.63 

 3.92 

5.47 

Minnesota 

Power-Taconite 

Harbor 

Furnace Sorbent Injection on Units 1 

through 3. 

1 

2 

3 

 1.56 

1.39 

1.37 

 0.67 

0.68 

0.67 

The combination of IPM 3.0 with these modifications results in a scenario called IPM 3.0 “will do.” 

Table 8.2, prepared by MRPO, shows the overall difference in emissions among IPM 2.1.9(VISTAS), 

IPM 3.0, and IPM 3.0“will do” scenarios for each state in the upper Midwest. 

Concerns have been raised as to whether adjusting IPM output compromises the integrity of the 

predictions. IPM assumes an energy balance throughout the EGU sector, and the concern is that 

modifications at a handful of facilities can throw the system off-balance. However, Minnesota views IPM 

as one method for predicting future EGU emissions and if states and affected industry believe that the 

predicted emissions are incorrect, they should change them in order to get the most accurate estimate of 

future emissions in the state. The corrections and adjustments made by Minnesota should not throw the 

system off-balance, as they generally address only changes in the performance of equipment, resulting in 

emission changes, and not overall energy balance. 

VISTAS states have also made post-IPM model adjustments for their states to the IPM 2.1.9(VISTAS) 

output. CENRAP has not made adjustments to the IPM 2.1.9(VISTAS) output used in their modeling. 

 

37 This IPM version is called IPM2.1.9(VISTAS) because the VISTAS RPO coordinated an IPM run based on 

EPA’s IPM version 2.1.9; but with CENRAP, MRPO and VISTAS member state modifications to the IPM input 

parameters related to committed (i.e. permitted) control projects at various EGUs that were not covered by the initial 

IPM version 2.1.9 run by EPA. 
43 

CENRAP intended to switch to IPM 3.0, but did not due to timing and financial reasons. The 

Minnesota(MRPO) modeling was able to easily include the revised IPM 3.0 EGU emissions in the future 

year inventory because, unlike other sectors, EGU emission projections with IPM are calculated 

independent of the base year inventory. 

Table 8.2: IPM2.1.9 (VISTAS), and IPM3.0 “base” and “will do” Alterations 

State Heat Input 

(MMBtu/year) Scenario SO2

(tons/year)

SO2

(lb/MMBtu) 

NOX

(tons/year) 

NOX 

(lb/MMBtu)

IL 

980,197,198 2001 - 03 (average) 362,417 0.74 173,296 0.35 

IPM 2.1.9 (VISTAS) 241,000 73,000 

1,310,188,544 IPM3.0 (base) 277,337 0.423 70,378 0.107 

IPM3.0 - will do 140,296 0.214 62,990 0.096 

IN 

1,266,957,401 2001 - 03 (average) 793,067 1.25 285,848 0.45 

IPM 2.1.9 (VISTAS) 377,000 95,000 

1,509,616,931 IPM3.0 (base) 361,835 0.479 90,913 0.120 

IPM3.0 - will do 628,286 0.832 128,625 0.170 

IA 

390,791,671 2001 - 03 (average) 131,080 0.67 77,935 0.40 

IPM 2.1.9 (VISTAS) 147,000 51,000 

534,824,314 IPM3.0 (base) 115,938 0.434 59,994 0.224 

IPM3.0 - will do 115,938 0.434 59,994 0.224 

MI 

756,148,700 2001 - 03 (average) 346,959 0.92 132,995 0.35 

IPM 2.1.9 (VISTAS) 399,000 100,000 

1,009,140,047 IPM3.0 (base) 244,151 0.484 79,962 0.158 

IPM3.0 - will do 244,151 0.484 79,962 0.158 

MN 

401,344,495 2001 - 03 (average) 101,605 0.50 85,955 0.42 

IPM 2.1.9 (VISTAS) 86,000 42,000 

447,645,758 IPM3.0 (base) 61,739 0.276 41,550 0.186 

IPM3.0 - will do 54,315 0.243 49,488 0.221 

MO 

759,902,542 2001 - 03 (average) 241,375 0.63 143,116 0.37 

IPM 2.1.9 (VISTAS) 281,000 78,000 

893,454,905 IPM3.0 (base) 243,684 0.545 72,950 0.163 

IPM3.0 - will do 237,600 0.532 72,950 0.163 

ND 

339,952,821 2001 - 03 (average) 145,096 0.85 76,788 0.45 

IPM 2.1.9 (VISTAS) 109,000 72,000 

342,685,501 IPM3.0 (base) 41,149 0.240 44,164 0.258 

IPM3.0 - will do 56,175 0.328 58,850 0.343 

SD 

39,768,357 2001 - 03 (average) 12,545 0.63 15,852 0.80 

IPM 2.1.9 (VISTAS) 12,000 15,000 

44,856,223 IPM3.0 (base) 4,464 0.199 2,548 0.114 

IPM3.0 - will do 4,464 0.199 2,548 0.114 

WI 

495,475,007 2001 - 03 (average) 191,137 0.77 90,703 0.36 

IPM 2.1.9 (VISTAS) 155,000 46,000 

675,863,447 IPM3.0 (base) 127,930 0.379 56,526 0.167 

IPM3.0 - will do 150,340 0.445 55,019 0.163 
44 

Minnesota Growth Changes in Minnesota(MRPO) 2018 Modeling Inventory 

Minnesota removed the EGAS estimated growth from taconite facilities in Northeast Minnesota and 

replaced it with MPCA generated growth estimates. The Minnesota(MRPO) 2018 inventory growth consists 

of three new taconite facilities in Northeast Minnesota; Mesabi Nugget, and a proposed “east mine” and 

“west mine” that reflect emissions projections for Polymet Mining and Minnesota Steel Industries. 

Emission units that did not operate in 2002 (and so were not in the 2018 inventory) were also added at 

two existing plants: United Taconite (Line 1), and Northshore Mining Silver Bay (Furnace 5). These 

emissions are present only in the Minnesota(MRPO) modeling. 

Controls on Future Year Inventory 

Control factors that reduce emissions are applied after growth and may be due to the addition of physical 

controls to a process. These controls may be voluntary or due to regulatory requirements. Controls also 

reflect federal and state regulations, legislation and permit actions. MRPO contracted with E.H. Pechan 

and Associates to identify controls to be implemented – termed “on-the-books” controls – between 2002 

and 2018 in source sectors except EGUs. In the MRPO inventory, the controls on all sectors (including 

EGUs) are: 

On-Highway Mobile Sources 

• Tier II/Low sulfur fuel; 

• Inspection/Maintenance programs in nonattainment areas (does not apply in Minnesota); and 

• Reformulated gasoline in nonattainment areas (does not apply in Minnesota). 

Off-Highway Mobile 

• Federal control programs incorporated into NONROAD model (e.g. nonroad diesel rule), and the 

evaporative Large Spark Ignition and Recreational Vehicle standards; 

• Heavy-duty diesel (2007) engine standard/Low sulfur fuel; 

• Federal railroad/locomotive standards; and 

• Federal commercial marine vessel engine standards. 

Electric Generating Units38

• Title IV Acid Rain Program (Phases I and II); 

• NOX SIP Call (does not apply in Minnesota); 

• Clean Air Interstate Rule. 

Other Point Sources 

• VOC 2-, 4-, 7-, and 10-year Maximum Achievable Control Technology (MACT) standards; 

• Combustion turbine MACT; and 

• Industrial boiler/process heater/RICE MACT. 

• The MRPO also included control factors to reflect settlement agreements for petroleum refineries 

and other non-EGU sources in MRPO states plus Minnesota.39

The Minnesota(MRPO) 2018 inventory includes the MRPO listed controls on the future year inventory. 

Minnesota emissions totals for 2002 and 2018 from the Minnesota(MRPO) inventory are shown in Table 8.3. 

Emissions totals for states surrounding Minnesota are provided in the TSD. 

 

38 These controls are included in the IPM3.0 projections. 39 MACTEC, 2006. 
45 

Table 8.3: Annual Minnesota 2002 and 2018 Emissions Totals in Tons40

2002 

Source Group SO2 NOX NH3 PM25 PM10 VOC 

Point 131,000 155,000 2,310 12,500 31,100 33,700 

Area 22,800 58,100 175,000 19,500 72,200 133,000 

Mobile On-road 29 172,000 7,200 2,200 2,200 97,600 

Non-road 9,210 102,000 98 5,600 6,380 96,800 

Biogenics 0 28,700 0 0 0 698,000 

Minnesota TOTAL: 163,000 516,000 185,000 39,900 112,000 1,060,000 

2018 

Source Group SO2 NOX NH3 PM25 PM10 VOC 

Point 83,500 117,000 3,420 25,100 47,900 42,800

Area 22,700 62,100 239,000 19,500 72,400 129,000

Mobile On-road 2 31,400 10,100 514 514 20,000

Non-road 2,170 76,900 125 4,410 5,030 86,700

Biogenics 0 28,700 0 0 0 698,000

Minnesota TOTAL: 108,000 317,000 253,000 49,600 126,000 977,000

Alternative EGU Emission Projections without CAIR. 

As described above, the on-the-books controls for EGUs presume CAIR is in effect. In July 2008, after 

the end of the initial public notice period for this SIP, the D.C Circuit Court of Appeals issued an opinion 

pointing out several “fatal flaws” with CAIR, and vacated the rule. The EPA petitioned for rehearing 

which included changing the remedy from vacatur to a remand. On December 23, 2008, the Court 

remanded CAIR to the EPA to be rewritten to address the flaws identified in the July ruling. This action 

means that CAIR is in effect while the flaws are addressed. 

One issue the EPA must address on remand is whether Minnesota should continue to be included in 

CAIR. The Court ruled in July that the EPA did not adequately respond to claims made by Minnesota 

Power that data on Minnesota emissions were inaccurate, and that by using better data Minnesota would 

fall below the threshold impact on a nonattainment area that was used for inclusion. 

In a letter dated October 31, 2008, from the EPA to Minnesota Power counsel, the EPA indicated its 

intent “to publish in the Federal Register a rule amending CAIR to stay the effectiveness of the rule with 

respect to sources located in the State of Minnesota. That administrative stay will remain in effect until 

such time as EPA determines through a rulemaking under the Clean Air Act whether Minnesota should be 

included in the CAIR region for fine particulate matter. EPA believes that in light of the Court’s decision, 

sources in Minnesota should not be required to make any additional expenditures to comply with CAIR 

prior to the expiration of the administrative stay of the rule.”41 A proposed rule to stay application of 

CAIR in Minnesota was published on May 12, 2009.42

At the time CAIR was vacated by the courts, the MRPO developed future year EGU emissions without 

CAIR in place. Rather than use the IPM model, which was used to model CAIR, the emissions withoutCAIR were developed using electricity generation forecasts from the Department of Energy’s Electricity 

Market Module Supply Regions by fuel type, and then applying known controls. Details on how the 

future year projections were estimated are in the TSD. 

 

40 To three significant digits. Totals may not add due to rounding. 

41 Meyers and Nakayama, 2008. 

42 74 FR 22147 
46 

Minnesota has determined that the known controls in 2018 with CAIR in place – as modeled in the IPM 

3.0 “will do” scenario and used to establish the RPG – and without CAIR in place – as shown in the 

MRPO Case B 2018 – are nearly identical for Minnesota. The resulting emissions projections are also 

very similar. Dissimilarities in emissions projections are attributed to differences in emission projection 

methods. The control assumptions in the IPM 3.0 “will do” scenario (with CAIR in place) and the 

controls without CAIR are shown in Table 8.4. 

Because of the similarities in EGU emissions projected in Minnesota, both with and without CAIR, the 

MPCA has continued to use the modeling including the IPM 3.0 “will do” projections for EGUs. 

Table 8.4: Future Year Control Assumptions with and without CAIR 

Facility Name Facility ID Stack 

ID 

Emission 

Unit ID 

Pollu

-tant 

Controls Without CAIR Controls With CAIR

Case B: Legally 

Enforceable 

Modeled in SIP 

(IPM v3.0"will do") 

2018 

Control 

EF 

Control Type 

2018 

Control 

EF 

Control Type* 

Xcel Energy - 

Riverside 

Generating 

Plant 

2705300015 

SV001 

EU001 NOX 100% removed 100% removed 

SO2 100% removed 100% removed 

EU002 NOX 100% removed 100% removed 

SO2 100% removed 100% removed 

SV003 

EU003 NOX 100% removed 100% removed 

SO2 100% removed 100% removed 

EU009 

NOX * new unit 

natural gas * new unit natural gas 

SO2 * new unit 

natural gas * new unit 

natural gas 

SV008 EU010 

NOX * new unit 

natural gas * new unit 

natural gas 

SO2 * new unit 

natural gas * new unit natural gas 

SV009 EU011 NOX 100% removed 100% removed 

SO2 100% removed 100% removed 

Minnesota 

Power Inc - 

Boswell 

Energy Ctr 

2706100004 SV003 EU003 

NOX 80% SCR 80% SCR 

SO2 85% FGD 85% FGD 

Rochester 

Public Utilities 

- Silver Lake 

2710900011 SV003 EU004 

NOX 40% SNCR ** ** 

SO2 85% SCRUBBER 95% SCRUBBER 

Xcel Energy - 

High Bridge 

Generating 

2712300012 

SV001 

EU001 NOX 100% removed 100% removed 

SO2 100% removed 100% removed 

EU002 NOX 100% removed 100% removed 

SO2 100% removed 100% removed 

EU003 NOX 100% removed 100% removed 

SO2 100% removed 100% removed 

EU004 NOX 100% removed 100% removed 

SO2 100% removed 100% removed 

SV008 EU010 

NOX * new unit 

natural gas * new unit 

natural gas 

SO2 * new unit 

natural gas * new unit natural gas 

SV009 EU011 

NOX * new unit 

natural gas * new unit natural gas 

SO2 * new unit 

natural gas * new unit 

natural gas 
47 

Facility Name Facility ID Stack 

ID 

Emission 

Unit ID 

Pollu

-tant 

Controls Without CAIR Controls With CAIR

Case B: Legally 

Enforceable 

Modeled in SIP 

(IPM v3.0"will do") 

2018 

Control 

EF 

Control Type 

2018 

Control 

EF 

Control Type* 

Xcel Energy - 

Sherburne 

Generating 

Plant 

2714100004 SV001 

EU001 NOX 50% LNB ** ** 

SO2 85% SCRUBBER   

EU002 NOX 50% LNB **  ** 

SO2 85% SCRUBBER   

SV002 EU003 NOX 50% LNB **  ** 

Xcel Energy - 

Allen S King 

Generating 

2716300005 SV001 EU001 

NOX 80% SCR 90% SCR 

SO2 82% SCRUBBER 82% SCRUBBER 

Minnesota 

Power Inc - 

Taconite 

Harbor Ctr 

2703100001 

SV001 EU001 NOX 50% ROFA/SNCR 50% ROFA/SNCR 

SO2 40% FSI 40% FSI 

SV002 EU002 NOX 50% ROFA/SNCR 50% ROFA/SNCR 

SO2 40% FSI 40% FSI 

SV003 EU003 NOX 50% ROFA/SNCR 50% ROFA/SNCR 

SO2 40% FSI 40% FSI 

Northshore 

Mining Silver 

Bay 

2707500003 

SV001 EU001 NOX 40% LNB 

SO2 20%*** Biomass 

SV002 EU002 NOX 40% LNB 

SO2 20%*** Biomass 

* Additional emissions for new units in the without-CAIR case were projected to be comparable to the IPM 3.0 

projections 

** These projects became legally enforceable after the IPM 3.0 “will do” case was developed. 

***This control, which is part of the BART determination for the unit, was not included in the final “Controls 

without CAIR” because the BART determination was incomplete at that time. 

Biomass: Co-firing biomass with existing fuel 

FGD: Fabric Filter/Flue Gas Desulfurization 

FSI: Furnace Sorbent Injection 

LNB: Low NOx Burner 

ROFA: Rotating Opposed Fire Air System 

SCR: Selective Catalytic Reduction 

SNCR: Selective Non-Catalytic Reduction 

MRPO Quality Assurance for Emissions Inventories 

While developing the emissions inventory and conducting emissions modeling, Minnesota participated in 

the MRPO quality assurance for emissions inventories. The MRPO assured the quality of the data 

through the review of emissions reports and spatial analysis.43 

• Emission Reports: EMS performs a number of checks and generates several reports, as documented 

in the EMS User’s Guide.44 The quality assurance checks for point sources, for example, include 

checks for missing or mislocated location data, missing or invalid state and county designation codes, 

missing facility name, missing or invalid Standard Industry Classification codes, and missing or outof-range stack parameters. The reports include tabular summaries of the state- and county-level 

emissions for point, area, and mobile sources; and various spatial plots of emissions. 

• Spatial Analysis: A second level of quality assurance is performed by the air quality modelers. The 

additional checks include evaluating spatial tile plots of total daily SO2, NOX, VOC, ammonia, PM2.5, 

 

43 Baker, 2004. 44 LADCO, 1999a. 
48 

and coarse mass emissions, and evaluating plots that show the variation in emissions from month to 

month, and from hour to hour. 

Canada Emissions Inventory 

In addition to including emissions from the individual states within the United States, CENRAP and 

MRPO included emissions from Canada in an attempt to accurately characterize the 2002 base year. 

Canada’s provinces report an emissions inventory to Environment Canada, similar to the states reporting 

the NEI to the EPA. The Criteria Air Contaminants Emission Inventory, a subset of Canada’s overall 

Pollutant Release and Transfer Register (PRTR), includes the relevant pollutants. 

However, Canada does not report emissions on the same schedule as the U.S., and a 2002 inventory was 

not available for use by the RPOs. The Canadian inventory is confidential and specifics are not shared 

freely outside the country. This makes it difficult to quality assure the data and understand whether the 

estimation methods are comparable. The MRPO has been collaborating with environmental staff in 

Ontario to better understand and implement improvements to the emissions estimates in that province. 

For their base year 2002 inventories, CENRAP and MRPO used the Canadian 2000 inventory. During 

the iterative modeling process, it was determined that much of the emissions in the 2000 Canada 

inventory were assigned no stack height and as a result were modeled with the emissions released in the 

surface layer of the atmosphere. These included some very large sources, whose emissions are, in reality, 

released at much higher elevations. Because of meteorological (i.e. wind direction and speed) differences 

throughout the various layers, revisions to the release height were required. CENRAP made these 

changes to the Canadian 2000 inventory based on 2005 data. MRPO, which was in the process of 

switching to a 2005 base year, chose to use the Canadian 2005 inventory, and with the help of Ontario 

environmental staff fixed the problems there. The Minnesota(MRPO) case replaces the 2000 Canada 

inventory with the Canada 2005 inventory. Because of the large uncertainties in the Canada inventory, 

Minnesota elected to use the Canada 2005 inventory for both the base year and future year. 

CENRAP used stack information from the Canada 2005 inventory to modify the Canada 2000 inventory, 

and used a Canada projected inventory from 2000 to 2018. The 2018 Canada inventory was distributed 

by the EPA and it is not clear whether EPA corrected the stack parameter problems with the 2018 Canada 

inventory. 

Air Quality/Meteorology Preparations and Results 

Emissions and meteorology were generated for every hour and allocated to 36km grids over the National 

Inter-RPO Domain. This domain was agreed upon by all the RPOs as the basic domain from which to 

model. The MRPO uses a subset of the national RPO domain, called the 4rpos domain, to focus on an 

area that includes the United States and Canada east of a line dissecting the United States at the westernmost tip of Texas. 

Both the National Inter-RPO Domain and the MRPO 4rpos domain are shown in Figure 8.1. CENRAP 

generated modeling emissions in a similar fashion, but encompassing the entire National Inter-RPO 36km 

domain. In addition to using the MRPO domain, Minnesota created a 12km flexi-nested domain and 

used the CAMx plume-in-grid tool to evaluate visibility impacts of individual elevated point sources 

located near the Class I areas. 
49 

Figure 8.1: Modeling Domains 

Performance Evaluation for Air Quality Models 

Meteorological Model Performance for the Base Year (2002) Data 

The meteorological data was prepared by Matthew Johnson of the state of Iowa. There are two model 

performance documents: Meteorological Modeling Performance Summary for Application to 

PM2.5/Haze/Ozone Modeling Projects45and Meteorological Model Performance Evaluation of an Annual 

2002 MM5 (version 3.6.3) Simulation v2.0.3.

46 Model performance was deemed good. 

Air Quality Model Performance for the Base Year (2002) Inventory 

Both CENRAP and MRPO have evaluated model performance over the entire domains they modeled. 

Because Minnesota is using MRPO inputs with emissions modifications, the state focused its own model 

performance on BWCAW and VNP. Particular attention was placed on the 20 percent best and worst 

days in the two Class I areas. 

Model performance evaluation is conducted on the base year, 2002, using the 2002 emission inventory 

(except for Canada) and meteorology. Several iterations of the 2002 base inventory were completed by 

MRPO, culminating in the final 2002 inventory that serves as the basis for the Minnesota(MRPO) modeling. 

Model performance evaluations of these iterations allowed for improving the emissions, meteorology and 

the CAMx model, resulting in improved model performance. The base year period used to evaluate 

model performance is the same as the base year used in the modeled attainment test. 

Minnesota evaluated performance of the model specifically at BWCAW and VNP; and for the 20 percent 

worst days. The speciated components used in the Minnesota(MRPO) evaluation are collected at IMPROVE 

monitor network sites. This network collects individual PM2.5 components at BWCAW and VNP. 

 

45 Baker et al., 2005. 

46 Johnson, 2004 – 2007. 

National Inter-RPO 36km Domain

MRPO "4rpos" 36km Domain

Minnesota 12km Nested Domain
50 

EPA guidance recommends considering various statistical assessments and other techniques of model 

versus observed pairs when conducting a performance evaluation for regional haze. The other techniques 

include spatial plots, time series plots and qualitative descriptions. Focus for the statistical assessment is 

on mean fractional bias and error. 

The statistical evaluation of the Minnesota(MRPO) modeling performance was done for 24-hour averaging 

times. Fractional bias and error are evaluated for 36km and 12km (with plume-in-grid) grid scale 

modeling. There are a total of 32 twenty percent worst days. Eight days are BWCAW only, 10 days are 

VNP only, and 14 days are shared between the two Class I areas. 

The conclusion of the performance evaluation specifically at BWCAW and VNP indicates model 

performance for sulfate is good throughout the year for all organizations. Nitrate performance is best in 

the colder months (quarter 1 and 4), but has some issues; organic carbon performance is good, except for 

five days associated with wildfires (wildfire emissions were not included in the modeling). Fine soil 

(crustal), and elemental carbon performance is good. Coarse particulate mass performs poorly, which is 

expected because coarser primary particles (largely composed of wind borne dust) do not travel far and 

are influenced by very nearby sources. The grid scale of the modeling cannot account for these local 

influences. Also, wind borne dust was excluded from the emissions inventory because of concerns about 

the transportable fraction of fugitive dust. 

Comparison of Minnesota(MRPO) and CENRAP Model Performance Evaluation for Nitrate on 

Individual Days 

The Minnesota(MRPO) and CENRAP performance evaluations show some conflicting performance results 

for nitrate. Figure 8.2 depicts the difference between Minnesota(MRPO) modeling and CENRAP averaged 

over the 20 percent worst days at VNP and BWCAW. The differences appear on some individual of the 

20 percent worst days. All these days occur in the winter and with winds traveling toward the Class I 

areas from the West and Northwest. The TSD contains the individual day model comparisons to 

observed – along with evidence of the direction of wind origination – for various individual days where 

the Minnesota(MRPO) modeling and CENRAP modeling perform very differently from one another. These 

are days where CENRAP overpredicts nitrate and the Minnesota(MRPO) model underpredicts nitrate. 

Figure 8.2: Observations and Predictions by Minnesota(MRPO) and CENRAP 

Extinction by Species at Averaged Over 20 Percent Worst Days 

VNP BWCAW 

0

10

20

30

40

50

60

70

80

obs MN(mrpo) CenRAP

Avg

Julian Date

Extinction (Mm-1)

SO4 NO3 OC EC CRUSTAL CM

0

10

20

30

40

50

60

70

80

obs MN(mrpo) CENRAP

Avg

Julian date

Extinction (Mm-1)

SO4 NO3 OC EC CRUSTAL CM
51 

Implications of the Performance Evaluation 

1. Reasonable Progress Goal Development. The model performance, especially for sulfate, fits within 

performance goals for developing regional haze policy.47 The underprediction of nitrate in the 

Minnesota(MRPO) modeling appears to be caused by a lack of ammonia available on the high nitrate 

days in the winter, which is discussed in more detail in the TSD supporting this SIP. This could make 

the model under-responsive to future NOX reductions. The CENRAP modeling, which appears to 

have too much ammonia, may have the opposite response. The reality is likely somewhere in 

between. The “Supplemental Analysis/Weight of Evidence Determination” section at the end of this 

Chapter 8 highlights how these model performance discrepancies for nitrate affect the results of the 

future year visibility conditions used to set reasonable progress goals. 

Poor performance of coarse mass is not a concern as coarse particulate mass is not a prominent 

component in the extinction calculation, nor is it significant in the extinction calculated at BWCAW 

and VNP on the 20 percent worst days (see Appendix 5.2), so changes in this component will not 

affect the resulting future year projection. 

2. Grid Scale Needs. The performance evaluation at the monitor locations is slightly better at 36km 

than for the Minnesota(MRPO) 12km(with plume-in-grid) grid for nitrate. Thus, the 36km modeling 

results are used for establishing the reasonable progress goal in deciviews at the monitor locations in 

BWCAW and VNP. The 12km (with plume-in-grid) results are used to address local contributions to 

regional haze impacts throughout each Class I area, but not for setting the RPG.48 When using 12km 

(with plume-in-grid) results, the performance evaluation results prompted Minnesota to assess 

visibility at multiple receptors located throughout VNP, BWCAW, and the western tip of Isle Royale. 

3. Horizontal Extent of Domain. Minnesota(MRPO) modeling performance for nitrate suggests it could 

benefit from extending the domain further west to encompass additional sources in Canada. 

However, because of the uncertainty of Canadian emissions development, Minnesota kept Canadian 

emissions constant between the base and future year. Thus, extending the domain would have no 

affect on the reasonable progress goals established in this SIP. Further discussion of Canadian 

contributions to regional haze is found in the TSD. 

4. Improvements to Emissions Inventory. Continued emissions/modeling and corresponding 

performance evaluations conducted by the RPOs have resulted in the best emissions inventory 

possible to date. Ammonia emissions estimates and response to changes in ammonia levels as it 

affects NOX emissions reductions (see #1), and better understanding of Canada’s inventory are areas 

to continue to explore. Based on the fit to model performance goals, and how the model results are 

applied in the establishment of reasonable progress goals, the MPCA believes that the base year and 

future year emission estimates used are sufficient to support this SIP. 

5. Modifications of Models. Model performance evaluations over entire domains have resulted in 

changes to models, made for some reason other than achieving regional haze goals. An example 

would be the secondary organic aerosol (SOA) module improvements in CMAQ, and more recently 

in CAMx. Although overall model performance for organic carbon may improve, model results 

without those improvements are acceptable in BWCAW and VNP. Also, improved SOA will not 

affect reasonable progress in BWCAW and VNP because natural biogenic emissions – which are the 

main source of SOA formation at the Class I areas– remain constant in the baseline and future year. 

As no controls are proposed for trees, thus they are not accounted for in development of the RRFs. 

 

47 U.S. EPA, OAQPS, 2007a. 

48 Minnesota evaluated reasonable progress using the 12km (with plume-in-grid) results for several receptors 

throughout the Class I areas. The 2018 projected values ranged from 18.3 – 19.0 deciviews, with an average value 

of 18.7 deciviews in the BWCAW – the largest Class I area – for the 20 percent worst days. The average value is 

the same as the 36km result at the monitor location. The same is true for the 20 percent best days. 
52 

Exploration of Potential Strategies for Demonstrating Reasonable Progress 

In addition to the “on-the-books” controls culminating in the 2018 emissions inventory described above, 

the MPCA explored other control measures, based on initial cost estimates by CENRAP, initial fourfactor analyses results from MRPO, and other measures under consideration in Minnesota. The MPCA 

looked at reductions in emissions resulting in a 0.25 lb/MMBtu limit on EGUs in Iowa, Missouri, North 

Dakota, and Wisconsin; reductions in SO2 and NOX emissions from point sources in Northeast Minnesota 

equaling a 30 percent reduction from 2002 emissions; and additional controls on a Minnesota utility 

located in central Minnesota. 

The source categories and regions approached while looking for additional reasonable control measures 

are based on an analysis of the source sectors and pollutant species in various geographic regions 

contributing to visibility impairment in 2018. The PSAT tool in CAMx was used in this assessment, and 

the focus was on the 20 percent worst days. 

The 2018 projections indicate that Minnesota is by far the largest individual state contributing to light 

extinction due to nitrate, sulfate and ammonium in the BWCAW and VNP. The next largest individual 

state contributors at BWCAW are Wisconsin, Iowa, Illinois, Missouri, and North Dakota. The next 

largest individual state contributors at VNP are North Dakota, Iowa, Wisconsin, and Canada.49 Figures 

8.3 and 8.4 show the percent contributions of these individual states, the remaining states, and Canada to 

total light extinction in 2018 presuming implementation of “on-the-books” controls. 

In the Figures, Boundary Conditions (BC) account for 11% at BWCAW and 15% at VNP of the visibility 

impairment. Boundary conditions are source contributions outside of the modeling domain. In the case 

of the regional haze SIP (and ozone and PM2.5 attainment modeling), they are the conditions derived from 

monthly averaged species output from the global scale chemical transport model (GEOS-CHEM) for the 

year 2002. Essentially, the GEOS-CHEM model is run at a much coarser grid resolution to allow for 

modeling global emissions. The GEOS-CHEM model output is processed to remove discrepancies 

between the grid scales, etc., and the GEOS-CHEM and CAMx model are linked at the CAMx domain 

boundary. 

Boundary conditions can transfer into and out of the CAMx modeling domain from the North, South, East 

and West. Ozone can also enter in from the top of the domain due to stratospheric infusion. Source 

apportionment techniques can only account for the total contribution of boundary conditions to the overall 

visibility conditions, which accounts for the conservation of mass in the apportionment modeling. 

 

49 Canada contributions based on 2005 emissions. 
53 

Figure 8.3: Nitrate, Sulfate, Ammonium Contributions to Extinction (Mm-1) in 2018 at BWCAW 

by Region for W20% Days 

Figure 8.4: Nitrate, Sulfate, Ammonium Contributions to Extinction (Mm-1) in 2018 at VNP by 

Region for W20% Days 

 

From the base year (2002) to the future year (2018), the regions specified above show less contribution to 

nitrate, sulfate and ammonium by somewhere between zero and about five percent. For example, Illinois 

contributes nearly five percent less at BWCAW in 2018 compared to 2002, resulting in a six percent 

contribution in 2018. 

In 2018, Minnesota contributes mainly sulfate, with lesser amounts of nitrate and ammonium; sulfate 

formation appears to result nearly equally from EGUs and non-EGU point sources. Ammonium is almost 

exclusively from agricultural ammonia sources. Contributions from other states have a similar makeup, 

but with less impacts from the non-EGU sector. 

The CENRAP case shows a higher contribution from nitrate sources than the Minnesota(MRPO) case and 

shows much less contribution to nitrate at BWCAW from onroad and nonroad sources in Minnesota, 

Illinois

6%

Iowa

8%

Wisconsin

10%

Canada

3%

AllOthers

22%

BC

11%

Minnesota

28%

NorthDakota

6%

Missouri

6%

Boundary 

Waters

Total 

Extinction 

of Nitrate, 

Sulfate & 

Ammonium: 

32 Mm-1

Illinois

3%

Minnesota

31%

Canada

5%

AllOthers

16%

BC

15% Iowa

7%

Wisconsin

6% NorthDakota

13%

Missouri

4%

Voyageurs

Total 

Extinction 

of Nitrate, 

Sulfate & 

Ammonium: 

32 Mm-1
54 

Canada, North Dakota and the western United states in 2018 than 2002. The CENRAP case shows 

significantly less contribution of point source sulfate from other states, but for Minnesota, there is more 

contribution from non-EGU point source sulfate from the base year to the future year. 

Over the 20 percent worst days, the Minnesota(MRPO) 12km PSAT results for 2018 indicate that Northeast 

Minnesota contributes 14 percent and the rest of Minnesota contributes 12 percent of total extinction at 

the BWCAW monitor location. Northeast Minnesota contributes 15 percent and the rest of Minnesota 

contributes 17 percent of total extinction at the VNP monitor location. Figures 8.5 and 8.6 illustrate the 

extinction contribution between Northeast Minnesota and the rest of Minnesota relative to contributions 

from all other geographic areas. 

As noted above, the 12km results suggest that contribution assessments should be conducted at several 

receptor locations throughout the Class I areas, rather than only at the monitor locations. Contributions 

from local (Northeast Minnesota), mostly point, sources assessed across the Class I areas (VNP, 

BWCAW, and the tip of Western Isle Royale) range from 4 – 19 percent of total extinction. The four 

percent appears at the western tip of Isle Royale, while the 19 percent contribution is in BWCAW. 

Contributions from the rest of Minnesota range from 9 – 17 percent; nine percent at the western tip of Isle 

Royale and the 17 percent at VNP. Figure 8.6 shows results at the receptor with the maximum 

(BWCAW, receptor 13) and the minimum (Western tip of Isle Royale) impact from Northeast Minnesota. 

Figure 8.5: Percentage Contribution of Northeast and Rest of Minnesota to BWCAW (BOWA1) 

and VNP (VOYA2) for W20% Days 

Boundary Waters: Total Extinction 30 Mm-1

AllOther

62%

BC

12%

NE 

Minnesota

14%

Rest of 

Minnesota

12%

MN 

Total:

26%

Voyageurs: Total Extinction 30 Mm-1

AllOther

53%

BC

15% Rest of 

Minnesota

17%

NE 

Minnesota

15%

MN 

Total:

32%
55 

Figure 8.6: Percentage Contribution of Northeast and Rest of Minnesota to Maximum (BOWA_13) 

and Minimum (ISLE) Receptors in the Class I areas for W20% Days 

Minnesota(MRPO) results for the 12km (with plume-in-grid) analysis indicate sulfate is the major 

component contributed by point sources in Northeast Minnesota, while the rest of the state is more evenly 

divided between sulfate from point sources and ammonium from agricultural sources. Figure 8.7 

illustrates the species contributions across the Class I areas. The Figure shows significantly less visibility 

impact due to Northeast Minnesota contributions to nitrate. This may seem counterintuitive because 

emissions of NOX in Northeast Minnesota are much higher than SO2. Point source emissions of NOX are 

about 37,500 tons per year, while SO2 emissions are just over 8,000 tons per year. 

Figure 8.7: Minnesota Contributions at Receptors Placed Throughout Boundary Waters, 

Voyageurs and the tip of Isle Royale in 2018 by Species and Geographic Region 

An explanation for this discrepancy in contribution of NOX and SO2 to the 20 percent worst days is that 

particulate nitrate is an issue on fewer days and is formed in the colder months. Viewing animated spatial 

plots of the source apportionment results on days with high nitrate show that winds on several of the days 

winds appear to be coming from the west and northwest of Minnesota. Thus, the NOX emissions are not 

AllOther

57%

BC

11%

Rest of 

Minnesota

13%

NE 

Minnesota

19%

MN 

Total:

32%

Boundary Waters: Total Extinction 34 Mm-1 

 (BOWA_13)

Isle Royale: Total Extinction 47 Mm-1

 (ISLE_1)

AllOther

78%

BC

10%

Rest of 

Minnesota

9%

NE 

Minnesota

3%

MN 

Total:

12%

0

1

2

3

4

5

6

SO4 NO3 NH4 SO4 NO3 NH4

NE Minnesota Rest of Minnesota

Extinction (Mm-1) lowerquartile minimum median maximum upperquartile

Rest MN Ext:

2.7 - 5.1 Mm-1

NE MN Ext:

1.6 - 6.5 Mm-1
56 

moving north toward the Class I areas to form ammonium nitrate, but are moving to the East, Southeast 

and South. 

Any actions taken based on these results should be done so with some caution. There are several 

remaining questions about ammonia emissions and nitrate. First, as mentioned previously, model 

performance for nitrate is worse than model performance for sulfate, and the model generally 

underpredicts the formation of nitrate, likely due to an underestimation of wintertime ammonia. Without 

ammonia monitors located in Northeast Minnesota, it is not possible to measure actual ammonia 

concentrations. Also, as noted in Chapter 9 (related to BART), emissions estimates for NOX from nonEGU point sources in Northeastern Minnesota may be less accurate than those for other point sources. 

Current future emissions estimates show significant SO2 emission reductions in the area. If there is 

considerably more ammonia in the system than represented in the Minnesota(MRPO) case , more ammonia 

may be available to form ammonium nitrate and a greater model response may be seen from reductions in 

NOX emissions. 

The uncertainties surrounding the impact of ammonia in the formation of ammonium nitrate and the 

resulting effect on visibility provide enough incentive not to discount the ability of NOX emission 

reductions to improve visibility. Therefore, potentially reasonable 2018 control measures for visibility 

should continue to include measures to reduce NOX emissions. 

The potentially reasonable measures explored in 2018 include: 

1. Estimated emission levels applied to the Xcel Energy – Sherburne County plant (located in 

central Minnesota) based on a January 2007 announcement of a potential project. This involves 

retrofit SCRs, fabric filters and dry scrubbers on Units 1 and 2 and SCR on Unit 3;50

2. A 0.25 lb/MMBtu emission rate from Iowa, Missouri, North Dakota and Wisconsin. These rates 

were applied to EGUs in those states that did not already have additional controls in place; and 

3. Additional emissions reductions associated with the Northeast Minnesota Plan, under which the 

six counties in northeast Minnesota would maintain a 30% reduction in NOx and SO2 from 2002 

emissions levels. About 21 percent of that reduction is already associated with Northeast 

Minnesota utility emission projections in the IPM version 3.0 “will do” scenario. The remaining 

approximately 10 percent was applied to taconite industry sources. The emission reductions were 

based on permit limits, furnace modifications in 2006 and 2007, fuel switching, a new scrubber, 

newer rate information, and some reductions due to BART. The details of these future year 

emissions estimations are specified in the TSD. 

 

Table 8.5 summarizes the 2018 point source emissions projections of SO2 and NOX associated with the 

potentially reasonable control measures and the emissions change from the 2018 Minnesota(MRPO)

emissions projections modeled. 

 

50 In a December 2007 filing, Xcel Energy dropped the proposal for SCR from all three units due to cost concerns. 

Instead they propose low NOX burners for NOX controls. The new proposal projects less SO2 emissions, but quite a 

bit more NOX emissions than the proposal reflected in the potentially reasonable control measures modeling. 
57 

Table 8.5: 2018 Annual Potentially Reasonable Control Measures Emissions for Point Sources 

Region SrcGroup Potentially 

Reasonable Control 

Measure Emission 

(ton/year) 

Emission Reduction 

from 2018 

(ton/year) 

Percent Reduction 

from 2018 

 SO2 NOX SO2 NOX SO2 NOX 

Iowa EGU 66,700 58,500 -47,200 0 -41% 

 non-utility 49,000 32,500 0 0 

Minnesota EGU 51,000 38,200 -2,980 -10,700 -6% -22%

 non-utility 26,000 57,700 -1,900 -6,550 -7% -10%

Missouri EGU 127,000 72,700 -111,000 0 -47% 

 non-utility 125,000 31,300 0 0 

North Dakota EGU 46,000 39,900 -12,300 -18,900 -21% -32%

 non-utility 19,000 11,600 0 0 

Wisconsin EGU 96,300 51,900 -48,200 0 -33% 

 non-utility 57,200 30,600 0 0 

The visibility analysis methodology, described at the beginning of this Chapter 8, was used to consider a 

reasonable progress goal were the potentially reasonable control measures in place. The resulting goals at 

BWCAW and VNP, due to the emissions reductions summarized above, are shown in Figures 8.8 and 8.9. 

The results show a potential reasonable progress goal at BWCAW of 18.3 deciviews and a potential 

reasonable progress goal at VNP of 18.7 deciviews. 

A straight line connecting the baseline visibility average (2000-2004) and natural conditions (2064) form 

the uniform rate of progress or “glidepath.” Placement relative to the line determines whether estimated 

future visibility (i.e. 2018) moves in a downward direction at such a rate that natural conditions are likely 

reached by 2064. A reasonable progress goal at VNP would be on the glidepath in 2018 if visibility 

impairment on the 20 percent worst visibility days were reduced from the baseline by a total of 1.7 

deciviews. [ −÷−×− ))20042064()20042018(()1.125.19( ]. BWCAW would be on the glidepath in 2018 if 

visibility impairment on the 20 percent worst days were reduced from the baseline by 2 deciviews. 

The reasonable progress assessment based on the potentially reasonable controls described above indicate 

that the goal for the 20 percent worst days would be a reduction from the baseline of 0.8 deciviews at 

VNP and 1.6 deciviews at BWCAW. Although the values show progress toward natural visibility 

conditions, obviously the 2018 goal would be positioned above the uniform rate of progress toward 

natural visibility conditions at both Class I Areas. 
58 

Figure 8.8: BWCAW 36-km Minnesota(MRPO) Potentially Reasonable Emissions Reduction Results 

Figure 8.9: VNP 36-km Minnesota(MRPO) Potentially Reasonable Emissions Reduction Results 

Uniform Rate of Progress - Boundary Waters, MN

3.4

18.3

19.9

11.6

6.4 6.5

0.0

5.0

10.0

15.0

20.0

25.0

1990 2000 2010 2020 2030 2040 2050 2060 2070

Year

Deciviews

Uniform Rate of Progress, Voyageurs MN

4.3

18.7

7.1

19.5

12.1

7.1

0.0

5.0

10.0

15.0

20.0

25.0

1990 2000 2010 2020 2030 2040 2050 2060 2070

Year

Deciviews
59 

Reasonable Progress Strategy and Goals 

Rather than set a reasonable progress goal based on potentialities, without determinations of 

reasonableness, the MPCA set the reasonable progress goal only considering the “on-the-books” controls 

(those controls expected due to programs other than the Regional Haze Rule) and the emissions strategy 

outlined in the Northeast Minnesota Plan. Based on these measures, the goal for the 20 percent worst 

days is a reduction from the baseline of 0.6 deciviews at VNP and 1.3 deciviews at BWCAW, as 

presented in Table 8.6 and illustrated in Figures 8.10 and 8.11. Further information on the reasonable 

progress goals, and why they are set at this level, is presented in Chapter 10. 

Table 8.6: Reasonable Progress Goals for BWCAW and VNP 

Class I Area Days 

Represented 

Reasonable 

Progress Goal for 

2018 in deciviews 

Difference Between 

RPG and URP in 

deciviews 

BWCAW 20% Worst 18.6 0.7 

20% Best 6.4 0.0 

VNP 20% Worst 18.9 1.1 

20% Best 7.0 0.0 

Figure 8.10: BWCAW 36-km Minnesota(MRPO) Results 

Uniform Rate of Progress - Boundary Waters, MN

3.4

18.6

11.6

19.9

6.4 6.5

0.0

5.0

10.0

15.0

20.0

25.0

1990 2000 2010 2020 2030 2040 2050 2060 2070

Year

Deciviews
60 

Figure 8.11: VNP 36-km Minnesota(MRPO) Results 

Supplemental Analysis/ Weight of Evidence Determination 

As mentioned above, there are differences among the future year projections modeled by CENRAP, 

MRPO and Minnesota(MRPO) available to derive reasonable progress goals for BWCAW and VNP. The 

resulting future year projections with on-the-books controls and some reasons for the differences are 

summarized here. Because the MRPO conducted modeling for both a 2002 and a 2005 base year, the 

MRPO 2002 base year modeling will be discussed first in relation to CENRAP and Minnesota(MRPO)

modeling, which also both use a 2002 base year. Discussion of the use of the 2005 base year follows. 

In order to do an equitable comparison, the visibility conditions and future year values for each 

organization were calculated using the same monitoring data establishing the baseline. The only 

difference lies in the modeled base year and future year concentrations, which are used to calculate RRFs 

applied to the baseline monitoring data. 

Table 8.7 contains the Minnesota(MRPO) projections51 for the 20 percent worst days at BWCAW and VNP 

along with the results of other modeling work conducted by CENRAP, and by MRPO for the 2002 base 

year. For the 20 percent worst days, the CENRAP results show future year projections that are the same 

at BWCAW, and 0.4 deciviews closer to the glidepath at VNP, than Minnesota(MRPO). The 

Minnesota(MRPO) projections are 0.3 deciviews closer to the glidepath at both BWCAW and VNP than 

MRPO. 

 

51 Minnesota(MRPO) values for the 12km grid assessed for several receptors throughout the Class I areas, indicated a 

range of 2018 projected values from 18.3 – 19.0 deciviews, with an average value of 18.7 deciviews in Boundary 

Waters for the 20 percent worst days. The average value is the same as the 36km result at the monitor location. The 

same is true for the 20 percent best days. It does not appear necessary to set separate goals for various locations 

across the Class I area based on the 12km results. 

Uniform Rate of Progress - Voyageurs, MN

4.3

18.9

12.1

19.5

7.1 7.1

0.0

5.0

10.0

15.0

20.0

25.0

1990 2000 2010 2020 2030 2040 2050 2060 2070

Year

Deciviews
61 

Table 8.7: Visibility Projections to 2018 using CENRAP, Minnesota(MRPO), and MRPO Modeling 

from a 2002 Base Year for the 20% Worst Days 

Reviewing the RRFs for the individual species can help gain a better understanding of why there are 

differences in the position relative to the URP. Table 8.8 contains the RRFs by visibility component, or 

species, for each organization. A factor above 1.000 means the modeled concentration increases from 

2002 to 2018. A factor below 1.000 means the modeled concentration decreases from 2002 to 2018. 

Table 8.8: Relative Response Factors to 2018 using CENRAP, Minnesota(MRPO), and MRPO 

Modeling from a 2002 Base Year for the 20% Worst Days 

Evaluation of the RRFs for BWCAW and VNP focuses on sulfate and nitrate. Both of these components 

figure prominently in the extinction calculation (see Chapter 5). Crustal/soil and coarse mass are not 

prominent components in the extinction calculation, nor are they significant in the extinction calculated at 

BWCAW and VNP on the 20 percent worst days (see Appendix 5.2), so changes in these components 

will not affect the resulting future year projection. Elemental carbon has low measured values at the two 

Class I areas; even though the extinction calculation multiplies the observed concentration of elemental 

carbon by a factor of 10, it still does not feature prominently in the future year projections at BWCAW 

and VNP. The RRFs for organic carbon are similar between the various analyses, so no further 

discussion is warranted for that component. 

Because the 2002 MRPO modeling is the basis for the Minnesota(MRPO) analysis, it is easier to compare 

these two analyses. According to the RRFs, the most noticeable differences between MRPO and 

Minnesota(MRPO) cases are in the response to sulfate reductions. As expected, the Minnesota(MRPO) 

modeling shows greater reductions due to the EGU emission projections associated with IPM version 3.0 

“will do”. The MRPO modeling for the 2002 base year used IPM version 2.1.9(VISTAS). 

The noticeable differences in RRFs for sulfate between CENRAP and Minnesota(MRPO) are also mainly 

due to the differences in future year EGU emission estimates. This conclusion is drawn from the 

similarity in the MRPO and CENRAP sulfate RRFs; both organizations used IPM version 

2.1.9(VISTAS). 

Baseline 2018 URP

(dv) (dv) (dv)

difference 

(dv)

Boundary Waters CenRAP 36 2002 19.9 17.9 18.6 0.7

Boundary Waters Minnesota 36 2002 19.9 17.9 18.6 0.7

Boundary Waters MRPO 36 2002 19.9 17.9 18.9 1.0

Voyageurs CenRAP 36 2002 19.5 17.8 18.6 0.8

Voyageurs Minnesota 36 2002 19.5 17.8 18.9 1.1

Voyageurs MRPO 36 2002 19.5 17.8 19.2 1.4

2018 Projected 

Class I Area Name

OrganizationGrid 

Resolution Base Year

sulfate nitrate

organic

carbon

elemental

carbon

crustal/

soil

coarse

mass

Boundary Waters CenRAP 36 2002 0.870 0.790 0.947 0.756 1.102 1.062

Boundary Waters Minnesota 36 2002 0.791 0.921 0.943 0.786 1.402 1.127

Boundary Waters MRPO 36 2002 0.877 0.929 0.949 0.788 1.265 1.112

Voyageurs CenRAP 36 2002 0.932 0.817 0.954 0.796 1.101 1.091

Voyageurs Minnesota 36 2002 0.848 1.031 0.954 0.834 1.275 1.069

Voyageurs MRPO 36 2002 0.949 1.054 0.956 0.830 1.200 1.064

Relative Response Factors

Class I Area Name

Organization GridBase

 Year
62 

Even more noticeable than the differences in sulfate RRFs, are the differences in RRFs for nitrate 

between the CENRAP and the MRPO and Minnesota(MRPO).cases. CENRAP RRFs show significantly 

more reductions in nitrate. These differences in nitrate RRFs overcome the sulfate decreases in the 

Minnesota(MRPO) modeling attributable to the change from IPM2.1.9 to IPM3.0, so that overall, the 

CENRAP position in relation to the URP is the same as the Minnesota(MRPO) results at BWCAW and is 

closer to the URP than the Minnesota(MRPO) results at VNP. The reasons for these differences are more 

complicated to discern because there are more underlying differences in the emissions inventories. The 

MPCA suspects that the greater reductions in nitrate in the CENRAP modeling are associated with the 

following: 

• While the Minnesota(MRPO) case keeps Canada emissions constant between the base year and the 

future year, the CENRAP case uses a 2000 and a projected 2018 Canadian inventory. Projected 

emissions in the CENRAP case contain lower Canadian NOX emissions in 2018 than in 2002. 

Thus, these emissions reductions could be reflected in the CENRAP RRF; and 

• The CENRAP case has significantly more ammonia than the Minnesota(MRPO) case. Model 

performance evaluation of the CENRAP modeling indicates overprediction of ammonium nitrate 

formation at BWCAW and VNP compared to observed values collected at monitoring stations. 

This is likely caused by additional NOX and a significant amount of available ammonia with 

which to react. These conditions allow the model to respond well to future projected reductions 

in NOX emissions, possibly even over-stating them. 

On the other hand, the Minnesota(MRPO) case underpredicts ammonium nitrate formation on the 

same days. The Minnesota(MRPO) case does not appear to have much available ammonia in the 

winter to form the same level of ammonium nitrate from NOX emissions as observed. In the 

future emissions estimates, NOX in the Minnesota(MRPO) case are reduced while ammonia 

significantly increases; the increased ammonia allows the model to form ammonium nitrate. 

Even though NOX emissions decrease, the corresponding increase in ammonia emissions and 

ammonium nitrate formation may prevent model response to the reduction in NOX emissions. 

Thus, the CENRAP case would reflect greater nitrate reductions in the RRF than the 

Minnesota(MRPO) case. In fact, the Minnesota(MRPO) RRFs show a slight increase in nitrate at VNP 

from 2002 to 2018. 

Based on the above premise regarding model response in nitrate RRF development above, the MPCA 

would anticipate the nitrate RRF would likely be somewhere between the CENRAP case (nitrate RRF of 

0.790 at BWCAW and 0.817 at VNP) and the Minnesota(MRPO) case (nitrate RRF of 0.921 at BWCAW 

and 1.031 at VNP). Should that prove true, visibility conditions would be closer to the URP in 2018 than 

projected in this SIP. 

As mentioned above, the MRPO switched from a 2002 base year to a 2005 base year for developing 

relative response factors. These factors are applied to the same 2000-2004 baseline. Applying 

substantially the same control measures52 to the 2005 base year as the 2002 base year resulted in future 

year projections at, or below, the URP at BWCAW and VNP. The resulting future year projections are 

0.7 deciviews lower at BWCAW and 1.2 deciviews lower at VNP than the Minnesota(MRPO) results. 

 

52 There are also emissions inventory differences. For example, the MRPO 2005 case was conducted using the 

2005 state emissions inventory for Illinois, Indiana, Iowa, Michigan, Minnesota (point sources), Ohio and 

Wisconsin, and more updated 2002 emissions inventory with growth factors to 2005 applied for other states (and 

Minnesota sources other than point sources). The MRPO 2005 case does not include the revised growth estimates 

for taconite facilities in Northeast Minnesota or the Northeast Minnesota Plan in the future year emissions estimates. 
63 

Inspection of the source apportionment results from the MRPO 2005 and the Minnesota(MRPO) 2002 cases 

suggests that much of the difference is due to the use of different meteorology, and a different set of 20 

percent worst days. The modeled RRFs for 2005 are established using the 20 percent worst days 

determined from 2005 monitoring data. Apportioning the 2005 model results to geographic regions of 

visibility impact on the 20 percent worst days and comparing that to similar apportionment results for the 

Minnesota(MRPO) 2002 case shows less contribution from Minnesota sources, much less contribution from 

the Western United States and Canada, and more contribution from states to the East and Southeast of 

BWCAW and VNP. The source apportionment results are available in the TSD. 

In order to verify the impact of the different meteorological year on the resulting RRFs, Minnesota 

modeled the 2002 emissions inventory (minus 2002 biogenic emissions) from the Minnesota(MRPO) case 

with the 2005 meteorology and 2005 biogenic emissions used in the MRPO 2005 case. The 2005 

biogenic emissions replace the 2002 biogenic emissions because these emissions are highly dependent on 

meteorology. Because biogenic emissions remain the same from the base year to the future year, use of 

2005 biogenics does not influence the resulting RRFs. 

Table 8.9 shows the future year projections resulting from this exercise. Table 8.10 shows the RRFs. 

The results of the Minnesota 2002 emissions\2005 meteorology future year projections are shown in 

relation to the Minnesota(MRPO) 200253 case and the MRPO 2005 case. The use of 2005 meteorology 

coupled with 2002 anthropogenic emissions results in future year projections 0.4 deciviews closer to the 

URP at BWCAW and 0.8 deciviews closer to the URP at VNP than the Minnesota(MRPO) 2002 case. The 

results demonstrate that the RRF, and hence, future year projections, are sensitive to meteorology and 

where the emission reductions occur geographically. In this case, it appears that the RRFs developed 

using 2005 meteorology are more sensitive to emission reductions that occur in states located to the East 

and Southeast of BWCAW and VNP. 

Table 8.9: Visibility Projections to 2018 using 2002 and 2005 Meteorology for the W20% Days 

 

53 The 2002 emissions/2005 meteorology modeling exercise was conducted using a future year that did not include 

the Northeast Minnesota Plan. Thus, the Minnesota(MRPO) case used for comparison in Table 8.10 has a future year 

projection 0.1 deciviews greater both BWCAW and VNP than Minnesota’s reasonable progress goal. 

Baseline 2018 URP

(dv) (dv) (dv)

difference 

(dv)

Boundary Waters Minnesota 36 2002* 19.9 17.9 18.7 0.8

Boundary Waters Minnesota 36 2002/05 met 19.9 17.9 18.3 0.4

Boundary Waters MRPO 36 2005 19.9 17.9 17.9 0.0

Voyageurs Minnesota 36 2002* 19.5 17.8 19.0 1.2

Voyageurs Minnesota 36 2002/05 met 19.5 17.8 18.2 0.4

Voyageurs MRPO 36 2005 19.5 17.8 17.7 -0.1

* The base year (2002) modeling used in the 2002-2005 comparison does not contain the NE Minnesota Plan

Class I Area Name

OrganizationGrid 

Resolution Base Year

2018 Projected 
64 

Table 8.10: RRFs for 2018 using 2002 and 2005 Meteorology for the W20% 

 

The supplemental analysis shows that the three modeling analyses produce RRFs that lead to varying 

approximations of future visibility conditions presuming the same “on-the-books” controls. In addition 

to the “on-the-books” controls, the Minnesota(MRPO) case also includes the Northeast Minnesota Plan; yet 

the reasonable progress goals established in this SIP are conservative in relation to those that would be 

established using the other modeling analyses. Nevertheless, all the estimated future visibility conditions 

are moving in the desired downward direction toward natural conditions. 

Continued emission inventory improvement projects are active, and a new base year emissions and 

meteorology, likely a 2007/2008 base year, are expected to be available for the five-year SIP assessment. 

The continuing analyses will provide additional evidence supporting future year projections, and 

establishment of reasonable progress goals toward natural visibility conditions. 

Data Access 

All data files used to support this SIP and the accompanying TSD are archived at the MPCA offices and 

provision has been made to maintain them. The MRPO and CENRAP maintain their own files for their 

work. The Minnesota(MRPO) files are generated and read on a Linux operating platform. Model outputs 

are processed with a series of Fortran programs invoked by C-shell scripts. To obtain files used in the 

analyses contact Margaret McCourtney at 651-757-2558 or margaret.mccourtney@state.mn.us. 

sulfate nitrate

organic

carbon

elemental

carbon

crustal/

soil

coarse

mass

Boundary Waters Minnesota 36 2002* 0.798 0.936 0.945 0.786 1.402 1.127

Boundary Waters Minnesota 36 2002/05 met 0.755 0.886 0.925 0.750 1.375 1.108

Boundary Waters MRPO 36 2005 0.746 0.849 0.990 0.800 1.269 0.596

Voyageurs Minnesota 36 2002* 0.855 1.035 0.956 0.834 1.275 1.069

Voyageurs Minnesota 36 2002/05 met 0.768 0.898 0.937 0.780 1.342 1.065

Voyageurs MRPO 36 2005 0.761 0.822 0.976 0.772 1.239 0.637

* The base year (2002) modeling used in the 2002-2005 comparison does not contain the NE Minnesota Plan

Relative Response Factors

Class I Area Name

Organization GridBase

 Year
65 

Chapter 9. Best Available Retrofit Technology 

The EPA’s 1999 Regional Haze Rule singles out certain older emission sources that have not been 

regulated under other provisions of the Clean Air Act for additional controls. The state of Minnesota is 

requiring these older sources that contribute to visibility impairment in Class I areas to install Best 

Available Retrofit Technology (BART). On July 6, 2005, EPA published a revised final rule, including 

40 CFR 51, Appendix Y, Guidelines for BART Determinations Under the Regional Haze Rule, which 

provides direction for determining which older sources may need to install BART and for determining 

BART. 

BART-Eligible Sources in Minnesota 

The facilities with BART-eligible units in Minnesota are shown in Table 9.1. A detailed description of 

each BART-eligible emission unit is included in Appendix 9.1. 

The BART-eligible sources were identified using the methodology in the Guidelines for BART 

Determinations under the Regional Haze Rules or Guidelines, referenced above. 

To identify the BART-eligible emission units in Table 9.1, MPCA used the following criteria: 

• One, or more, emission(s) units at the facility fit within one of the twenty-six (26) categories 

listed in the Guidelines; 

• The emission unit(s) were in existence on August 7, 1977 and began operation at some point on 

or after August 7, 1962; and 

• The sum of the potential emissions from all emission unit(s) identified in the previous two bullets 

was greater than 250 tons per year of the visibility-impairing pollutants: sulfur dioxide (SO2), 

nitrogen oxide (NOx), and PM10. 

Table 9.1: Minnesota Facilities with BART-eligible Units 

BART Source 

Category Name 

SIC 

Code Facility ID Facility Name BART Emission Units (Emission Unit No.) 

Fossil Fuel-fired 

Steam Electric 

Plants > 250 

MMBtu/hour -- 

Electric Generating 

Units (EGU) 

4931 2709900001 Austin Utilities NE Power Station *Boiler No. 1 (EU001) 

4931 2713700027 Hibbing Public Utilities North boiler (EU003) 

4911 2703100001 MN Power, Taconite Harbor *Boiler no. 3 (EU003) 

4911 2706100004 MN Power, Boswell Energy Center *Boiler no. 3 (EU003) 

4931 2701500010 New Ulm Public Utilities No. 4 boiler (EU003) 

4911 2711100002 Otter Tail Power Hoot Lake *Unit 3 boiler (EU003) 

4911 2710900011 Rochester Public Utilities, Silver Lake Unit #3 boiler, *Unit #4 boiler 

(EU003, EU004) 

4911 2713700028 Virginia Public Utilities Boiler no. 9 (EU003) 

4911 2714100004 Xcel Energy, Sherco *Boilers 1 and 2 (EU001,EU002) 

4911 2716300005 Xcel Energy, Allen S King *Boiler 1 (EU001) 

4911 2705300015 Xcel Energy, Riverside *Boiler 8 (EU003) 

Petroleum 

Refineries 

2911 2703700011 Flint Hills Resources LP – Pine Bend 15 emission units 

2911 2716300003 Marathon Ashland Petroleum LLC 24 emission units 

Taconite Ore 

Processing Plants 

1011 2713700063 US Steel, Keewatin Taconite 32 emission units 

1011 2713700061 Hibbing Taconite Co 29 emission units 

1011 2713700005 US Steel, Minntac 375 emission units 

1011 2713700113 United Taconite LLC 

(formerly EVTAC) 54 emission units 

1011 2713700062 ArcelorMittal 

(formerly Ispat Inland Mining) 32 emission units 
66 

BART Source 

Category Name 

SIC 

Code Facility ID Facility Name BART Emission Units 

(Emission Unit No.) 

1011 2707500003 Northshore Mining Company, Silver 

Bay 

43 emission units 

(*EU002 was a CAIR EGU) 

Fossil fuel fired 

boilers of more 

than 250 

MMBTU/hr 

2063 2711900002 American Crystal Sugar, E. Gr. Forks Boilers 1 and 2 (EU001, EU002) 

2063 2712900014 Southern MN Beet Sugar Boiler no. 1 (EU001) 

Kraft Pulp Mills 

2621 2707100002 Boise White Paper LLC, Intl Falls 

#2 boiler, recovery furnace, 

smelt dissolving tank (EU340, 

EU320, EU322) 

2611 2701700002 Sappi Cloquet, LLC #7, #8 power boilers (EU002, 

EU037) 

Iron and Steel Mill 

Plants 3312 2712300055 Gerdau Ameristeel Reheat furnace (EU004) 

 Secondary Metal 

Production 

Facilities 

3341 2703700016 Gopher Resources 

3 emission units in reverberatory 

furnace area (EU003, EU007, 

EU008) 

 * These Electric Generating Units were initially covered under the Clean Air Interstate Rule (CAIR). 

The Guidelines recommend addressing the visibility-impairing pollutants SO2, NOX, and Particulate 

Matter. The MPCA addressed these three pollutants and used particulate matter less than ten (10) 

microns in diameter (PM10) as an indicator for particulate matter to identify BART-eligible units. 

Consistent with the Guidelines, MPCA did not evaluate emissions of Volatile Organic Compounds 

(VOCs) and ammonia in BART determinations for these reasons: 

Ammonia: In the Guidelines, EPA suggests that states consider ammonia as a precursor to PM2.5

formation on a case-by-case basis. They make the point that “states are required to make BART 

determinations only for stationary sources that fall within certain industrial categories.” A perusal of the 

specific industrial categories in Minnesota indicates that these sources do not emit ammonia in a 

“significant” (potential to emit 250 tons per year or more) amount. Thus, the inclusion of ammonia – 

while a potential contributor to visibility impairment – would not impact the MPCA’s BART-eligibility 

determination. Ammonia from sources that may contribute to visibility impairment is included in the 

regional scale modeling used in this SIP. 

VOCs: In the Guidelines, EPA suggests that states consider VOCs as a precursor to PM2.5 formation on a 

case-by-case basis. Only specific VOC compounds form secondary organic aerosols that affect visibility, 

and these compounds are a fraction of the total VOCs reported in the emissions inventory. For the BART 

analysis, MPCA does not have the breakdown of VOC emissions necessary to model those that only 

impair visibility. Although not included in BART, VOCs – both anthropogenic and biogenic – are 

included in the regional scale modeling used in this SIP 

The MPCA identified BART-eligible sources in the state by sending a Request for Information by 

certified mail to all facilities in the state that are major sources for New Source Review. The Request for 

Information asked the facility to identify its industrial category, any units constructed between 1962 and 

1977, and the potential emissions from these units. If the facility identified BART-eligible units, 

additional information about those units was requested so that the MPCA could model the visibility 

impacts of those units. The MPCA also reviewed its databases to ensure that no BART-eligible units may 

have been overlooked in the survey process. Additional information about the identification process is 

contained in Appendix 9.1. 
67 

Determination of Sources Subject to BART 

Under the Guidelines, the state has the following options regarding its BART-eligible sources: a) make 

BART determinations for all sources; or b) consider exempting some sources from BART because they 

do not cause or contribute to visibility impairment in a Class I area. The MPCA chose option b. The 

Guidelines then suggest the following three modeling options for determining which sources may be 

exempt: 

• Individual source attribution approach (dispersion modeling). 

• Use of model plants to exempt sources with common characteristics. 

• Cumulative modeling to show that no sources in a state are subject to BART. 

The state of Minnesota chose to use the individual source attribution approach to determine which sources 

are subject to BART. 

The MPCA performed source-specific analyses using the CALPUFF model to determine which sources 

cause or contribute to visibility impairment; the CALPUFF modeling protocol used for determining 

which facilities are subject to BART is included in Appendix 9.2. 

In accordance with the recommendation of the Guidelines, a contribution threshold of 0.5 deciviews was 

used in determining those sources that are subject to BART. The MPCA chose to use the 98th percentile 

0.5 deciview threshold because EPA states in its Guidelines, “As a general matter, any threshold that you 

use for determining whether a source ‘contributes’ to visibility impairment should not be higher than 0.5 

deciviews.”54 The MPCA is not aware of any special circumstances in Minnesota that would merit the use 

of a higher threshold. The Guidelines provide states the discretion to set a threshold below 0.5 deciviews 

if “the location of a large number of BART-eligible sources within the state and in proximity to a Class I 

area justifies this approach.” 

The MPCA took into account four factors in analyzing the use of the 0.5 deciview threshold for subjectto-BART: 

• How close the BART-eligible source contributions are to the 0.5 threshold; 

• Total facility control measures/emission reductions gained by federal regulations and during 

the establishment of reasonable progress goals in the RH SIP; 

• Visibility improvement gains from BART; and 

• The tool (CALPUFF) used to determine subject-to-BART status and its applicability to 

regional haze analyses. 

Although the MPCA could set the contribution threshold lower than 0.5 deciviews and is cognizant of a 

number of existing sources in close proximity to Class I areas, the modeling showed no sources causing 

impacts at levels just slightly below 0.5 deciviews. The 98th percentile deciview values for those subjectto-BART range from 0.6 – 4.4 deciviews, while the 98th percentile deciview values for those not subjectto-BART range from 0.0 – 0.4 deciviews. 

A total of 15 facilities with BART-eligible sources were determined not subject-to-BART based on the 

0.5 deciview threshold. Of those 15 facilities, three are subject to the Northeast Minnesota Plan and three 

are EGUs that were initially subject to CAIR. Minnesota was initially included in CAIR, leading many 

utilities to install controls in anticipation of CAIR compliance. EPA has recently published a proposed 

stay of CAIR in Minnesota until there is a repromulgated CAIR rule. Should Minnesota not be included 

 

54 Regional Haze Regulations and Guidelines for Best Available Retrofit Technology (BART) Determinations, Final 

Rule, (2005). p. 39161 
68 

in a repromulgated rule, two of the three EGUs that showed modeling results closest to the BART 

threshold (Austin Public Utilities and Otter Tail Power Hoot Lake) will be re-evaluated for reasonable 

progress controls at the time of the Five Year SIP Assessment. 

Based on these facts, the application of BART would likely have little impact on the emission reductions 

expected from these facilities. Of the remaining nine facilities not subject to the Northeast Minnesota 

Plan or initially subject to CAIR, all have 98th percentile deciview values of 0.2 deciviews or less. 

Therefore, MPCA did not readjust the contribution threshold chosen for exempting sources from BART. 

The MPCA published the proposed BART implementation strategy in the State Register on September 6, 

2005; comments were requested and received, and the MPCA responded to the comments. Appendix 9.2 

details where to find information on the strategy and the MPCA’s response to comments. 

The facilities found by the MPCA to be subject to BART are shown in Table 9.2. Again, Appendix 9.2 

contains information on how to find the detailed results of the modeling analyses for each BART-eligible 

source. Facilities found to be subject to BART must complete a BART analysis, unless the MPCA 

exempted them from that requirement. 

Table 9.2: Facilities with Units Subject to BART in Minnesota 

BART Source 

Category Name 

Facility ID Facility Name Emission Units Subject 

to BART 

(Primary Contributor) 

Max. Modeled # 

days > 0.50 dv 

from 2002-2004a

Taconite ore 

processing 

facilities 

2713700063 US Steel, Keewatin 

Taconite 

32 emission units 

(Line 1) 247 

2713700061 Hibbing Taconite Co 29 emission units 

(Lines 1,2,3) 247 

2713700005 US Steel, Minntac 375 emission units 

(Lines 3,4,5,6,7) 530 

2713700113 United Taconite 54 emission units 

(Lines 1,2) 442 

2713700062 ArcelorMittal 32 emission units (Line 1) 228 

2707500003 Northshore Mining, 

Silver Bay 

42 taconite processing 

emission units 

(Lines 11,12) 

169 

Fossil Fuel-fired 

Steam Electric 

Plants > 250 

MMBtu/hour – 

Electric 

Generating Units 

(EGU) 

2703100001 MN Power, Taconite 

Harbor Boiler No. 3 (EU003) 226 

2706100004 MN Power, Boswell 

Energy Center Boiler No. 3 (EU003) 205 

2707500003 Northshore Mining, 

Silver Bay 

Boiler No. 2 only 

(EU002) 316 

2710900011 Rochester Public 

Utilities, Silver Lake 

Unit #3 boiler, Unit #4 

boiler (EU003, EU004) 17 

2714100004 Xcel Energy, Sherco Boilers 1 and 2 (EU001, 

EU002) 230 

a

Complete modeling results are available at http://www.pca.state.mn.us/publications/aq-sip2-07.pdf. Results are 

pre-control upgrades. 
69 

Determination of BART Requirements for Subject-to-BART Sources

BART is the emission limit for each pollutant based on the degree of reduction achievable through the 

application of the best system of continuous emission reduction, taking into consideration: the costs of 

compliance, the energy and the non-air quality environmental impacts of compliance, any pollution 

control equipment in use at the source, the remaining useful life of the source, and the degree of 

improvement in visibility which may reasonably be anticipated to result. However, a state is not required 

to make a determination of BART for SO2, NOX, or PM10 if a BART-eligible source has the potential to 

emit (PTE) less than 40 tons per year of SO2 or NOX or less than 15 tons per year for PM10. 

EPA’s BART Guidelines set forth a process for making BART determinations that may be used by states; 

this process is mandatory for 750 MW power plant sources, but advisory for other sources. The MPCA’s 

BART determinations are influenced largely by two factors: the technology available and the costs of 

compliance. The technology available particularly influenced the determination of BART for the taconite 

facilities. In some other cases, technically feasible and cost effective controls were not determined to be 

BART due to concern over other environmental impacts, namely water discharge. Existing air pollution 

control equipment at the source is taken into account in the cost effectiveness of controls, and where it 

impacts the determination of feasible additional controls. In no instance did the MPCA or an affected 

facility identify units where the emitting unit’s remaining useful life mitigated the selected control option. 

All units are presumed to continue operating for at least 20 years for the cost estimating procedures. 

Finally, the MPCA largely did not rely on evaluations of resulting visibility improvement in choosing 

controls, except in a case where a facility was only marginally subject-to-BART, and therefore BART 

controls were not required on one of two BART units. In cases where full BART determinations were 

requested, the facilities estimated visibility improvement from various BART options, and these are 

included in the memos documenting the MPCA’s BART determinations. However, the MPCA’s position 

is that cost-effective controls should be installed, even if they result in limited improvement in visibility, 

and technically infeasible or not cost-effective controls are not required under BART, even if they result 

in significant visibility improvement. Controls approximating MPCA’s BART determinations for EGUs 

were included in the visibility modeling used to set the RPGs, thereby demonstrating “the degree of 

visibility improvement which may reasonably be anticipated from the use of BART.” 

EGU BART Determinations 

The MPCA initially did not perform a BART determination for subject-to-BART EGUs to evaluate NOX

and SO2 because of Minnesota’s inclusion in the Clean Air Interstate Rule (CAIR). EPA found that, as a 

whole, the CAIR cap-and-trade program improves visibility more than implementing BART in states 

affected by CAIR. A state that opts to participate in the CAIR program need not require affected BARTeligible EGUs to install, operate, and maintain BART. BART-eligible EGUs in both CAIR states and 

non-CAIR states must submit a BART determination if the state finds they are subject to BART. If a state 

accepts EPA’s overall finding that CAIR “substitutes” for BART, then the BART determination need 

only be done for PM emissions, as NOX and SO2 emissions are addressed by CAIR. 

In addition, as the MPCA began the process of looking at BART controls, it appeared that all but one 

EGU otherwise subject-to-BART would be adding controls with implementation expected by 2010. This 

is shown in Table 9.3. 

However, subsequent legal uncertainty concerning CAIR, as well as several comments received on the 

draft SIP, led to reconsideration of the decision to allow CAIR to substitute for BART. Although CAIR 

went into effect, as written, on January 1, 2009, EPA issued a proposed rule on May 12, 2009 to stay the 
70 

effectiveness of CAIR in Minnesota.55 The MPCA therefore has made BART determinations for the six 

EGUs found to be subject to BART. In most of these cases, planned controls for SO2 and NOX have been 

determined to represent BART levels of control. 

The MPCA modeled the PM visibility impacts from each subject-to-BART EGU and found that impacts 

were less than 0.20 deciview for all units, also shown in Table 9.3. Because of the small impact from the 

PM emissions, the MPCA determined that any additional control would not be cost effective, particularly 

when weighed against the small amount of visibility improvement and other environmental impacts. In 

addition, all of the subject-to-BART EGUs already have PM controls installed and some are planning PM 

control upgrades.56 Therefore, each facility’s existing controls and emission limits for PM were 

considered to be BART. 

Table 9.3: Planned Control Upgrades by Subject-to-BART EGUs and Projected PM Contribution 

to Visibility Impairment 

Facility ID Facility Name 

Emission 

Units Subject 

to BART 

Estimated % 

Reduction 

Over Average 

‘01-‘03 lb/ 

MMBTU 

Emission Rate 

Estimated 

Year Control 

Upgrade 

Project 

Completed 

Maximum Modeled 

Contribution to 

Visibility 

Impairment from 

PMa 

(Δ dv) 

2703100001 MN Power, Taconite 

Harbor 

Boiler no. 3 

(EU003) 

NOX- 66% 

SO2- 63% 2009 0.078 

2706100004 MN Power, Boswell Boiler no. 3 

(EU003) 

NOX- 81% 

SO2- 90% 

PM10- 65% 

2009 0.048 

2710900011 Rochester Public 

Utilities, Silver Lakeb Unit #4 boiler 

(EU004) 

NOX- 63% 

SO2- 85% 

2009 – NOX 

2010 – SO2 0.005 

2714100004 Xcel Energy, Sherco 

Boilers 1 and 2 

(EU001, 

EU002) 

NOX-43-45% 2006-2008 0.047 

2707500003 Northshore Mining, 

Silver Bay 

Boiler 2 

(EU002) 

No upgrades 

announced 

No upgrades 

announced 0.16 

a Results shown are from CAMx modeling performed by MPCA staff using 2002 emissions input. More 

information can be found in the TSD. 

b The MPCA has determined that BART for Unit 3 is no additional control because Units 3 and 4 combined were 

found to be only “marginally” subject-to-BART and significant control upgrades are planned for Unit 4, the larger 

BART unit. Unit 4 impacted visibility more than Unit 3 as its 2002 SO2 emissions were about four times those of 

Unit 3. In addition, the Title V permit issued in September 2007 requires additional emission reduction strategies 

(to be determined) for SO2 attainment. 

 

55 74 FR 22147 

56 Minnesota Power is installing BACT-like PM controls on Boswell 3 as part of its voluntary emission reduction 

project. 
71 

Table 9.4 documents the NOX and SO2 BART determinations made by the MPCA for the subject-to 

BART EGUs. 

Table 9.4: NOX and SO2 BART Determinations for EGUs 

Facility Name Emission Unit 

NOX Bart 

Technology 

NOX BART 

Limit 

(lbs/MMBtu) 

SO2 BART 

Technology 

SO2 BART 

Limit 

(lbs/MMBtu) 

MN Power, Taconite 

Harbor 

Boiler no. 3 

(EU003) 

ROFA 0.20 FSI and FF 0.40 

MN Power, Boswell Boiler no. 3 

(EU003) 

LNB + OFA, 

SCR 0.07 Wet scrubber 0.09 

Rochester Public 

Utilities, Silver Lake 

Unit #3 boiler 

(EU003) No additional No Limit No additional 2.30 

Unit #4 boiler 

(EU004) 

ROFA/Rotamix 0.25 Spray dryer 

absorber 0.60 

Xcel Energy, Sherco 

Boiler 1 

(EU001) 

LNB +SOFA+ 

Combustion 

Optimization 0.15 Retrofit FGD with 

sparger tubes 0.12 

Boiler 2 

(EU002) 

Combustion 

optimization 

Northshore Mining, 

Silver Bay 

Boiler 1 

(EU001) LNB + OFA 0.41 Biomass co-fire 0.41 

Boiler 2 

(EU002) 

LNB + OFA 0.40 Biomass co-fire 0.48 

Appendix 9.4 contains the MPCA’s full BART analysis and determinations, including appropriate 

emission limits, for NOX, SO2, and PM10 at each subject-to-BART EGU. 

As shown in Appendix 9.7, the MPCA promulgated a rule that makes the requirements of BART 

“Applicable Requirements” for facilities. The MPCA will therefore add BART requirements to affected 

facility’s Title V permits as a basis for permit limits. Due to the length of time that is necessary to reopen a permit and amend requirements, the MPCA is not likely to have these requirements fully 

incorporated into Title V permits until the Five Year SIP Assessment. Since Minnesota rules mandate 

that permits include all applicable requirements, the BART requirements must be included. 

Visibility Improvement

The MPCA modeled the visibility improvement expected from the installation of the BART controls 

shown in Table 9.4. The modeling compared actual emissions as modeled for the 2002 base year 

modeling to the emissions expected with the installation of BART, using two years of meteorology (2002 

and 2005). The overall results are documented in each BART determination memo in Appendix 9.4, with 

more explanation of the methodology and more detailed results in Appendix 9.5. 

Taconite BART Determinations 

Table 9.5, below, describes the characteristics of Minnesota’s taconite pellet furnaces, which are the other 

main source category subject-to-BART. BART requirements for the taconite sources are shown in Tables 

9.6 and 9.7 for each visibility impairing pollutant. 

The BART analysis conducted by the facilities for each subject-to-BART source is listed in Appendix 

9.2. BART for each subject-to-BART source was determined by the state taking into account the required 
72 

factors. However, determining BART for the pellet furnaces at Minnesota’s taconite plants is more difficult 

than for EGUs or other, more common, types of equipment. 

Eight taconite plants exist nationally: six in Minnesota and two in Michigan. The first new taconite plant to 

be built in over 30 years is not scheduled to begin operation until 2010. The lack of new taconite plants and 

retrofit projects at existing plants as well as the uniqueness of the industry and the individual facilities (see 

Table 9.5) means that very few add-on control strategies are known to be feasible for taconite pellet 

furnaces. Even fewer control strategies are known to be cost-effective or otherwise reasonable. 

Table 9.5: Characteristics of Minnesota Taconite Pellet Furnaces57 

Plant (line) Pelletizer type Pellet type Pellets fired, 

Long ton/hr 

Fuel Existing 

Control 

Keetac Grate Kiln Standard 600-660 PRB58 coal-NG Wet scrubbera

Hibbing Taconite 

1 Straight Grate Standard 250-380 NG Wet scrubber 

2 Straight Grate Standard 250-380 NG Wet scrubber 

3 Straight Grate Standard 250-380 NG Wet scrubber 

Minntac b 

3 Grate Kiln Standard 200-250 NG Wet scrubbera 

4 Grate Kiln Flux/standard 400-450 60%wood-40% NG Wet scrubber 

5 Grate Kiln Flux/standard 400-450 60%wood-40% NG Wet scrubber 

6 Grate Kiln Flux 400-450 PRB coal-NG Wet scrubber 

7 Grate Kiln Flux 400-450 PRB coal-NG Wet scrubber 

United Taconite c 

1 Grate Kiln Standard 170-270 NG Wet scrubber 

2 Grate Kiln Standard 480-550 Pet coke-coal Wet scrubber 

ArcelorMittal d Straight Grate Flux 310-440 NG Wet scrubber 

Northshoree 

11 Straight Grate Standard 235-255 NG Wet-Wall ESP 

12 Straight Grate Standard 235-255 NG Wet-Wall ESP a

 Scrubber adds lime to enhance SO2 removal 

b

 Minntac can fire wood + NG in L3 through L7 but typically uses the fuels as shown above. 

Minntac can make standard or flux pellets in L3 through L7 but typically schedules production as shown above. 

c

 United Taconite’s Line 2 is permitted to burn coal and petroleum coke with no coal type specified. 

d

 ArcelorMittal can make standard pellets but typically does not; data comes from stack test results during flux pellet 

production. 

e

 Northshore can make flux pellets in its furnaces without adding auxiliary burners in the preheat zone; pellet type is 

not seen in the stack test reports. 

The MPCA has determined that BART for NOX for all taconite pellet furnaces is an operating standard of 

good combustion practices in combination with process changes proposed as BART by the facilities, such 

as low-NOX burners in pre-heat zones, ported kilns, and modified furnace design for improved fuel 

efficiency. 

BART for most direct PM emissions was determined to be equivalent to the taconite MACT, which 

requires control of PM emissions to control hazardous air pollutants. (Some PM emission sources are not 

covered by the taconite MACT.) Due to the MACT, the taconite facilities already have particulate 

control, with five facilities operating wet scrubbers and one wet-wall electrostatic precipitators (ESPs). 

The taconite MACT establishes a PM10 limit of 0.01 grains per dry standard cubic foot for the pellet 

furnaces at each of the six taconite plants. 

 

57 Table 9.3.2 in Appendix 9.3 contains additional information. 

58 PRB coal is Powder River Basin coal, which is generally low sulfur. 
73 

BART for SO2 for these units was generally determined to be the existing particulate scrubber optimized 

for SO2 removal, as in most cases, add-on scrubbers were not cost-effective. The one exception is United 

Taconite’s Line 2. This line burns a combination of high sulfur fuels: petroleum coke and coal in varying 

blends with natural gas. MPCA has determined that the SO2 BART limit for this line is 1.7 lbs/MMBtu, 

and believes that this limit can be met either through fuel blending, installation of an additional polishing 

scrubber, or a combination. 

 

Due to the lack of emissions data representing the range of operating conditions that influence emissions 

and the inability to predict emissions using operating parameters, the MPCA is unable at this time to set 

an emission limit that corresponds to BART for SO2 and NOX at most facilities, and it would be difficult 

to determine continuous compliance with a limit for most taconite pellet furnaces. In particular, the 

seeming variance of NOX emissions at all furnaces (similar to NOX variability at cement kilns) and SO2

emissions at facilities that burn fuels other than natural gas prevents the MPCA from setting a meaningful 

BART emission limit at this time for those situations. 

Therefore, the only specific BART limits that the MPCA has been able to include at this point are SO2

emission limits for those taconite lines that burn low-sulfur fuels, such as natural gas or biomass, as their 

primary fuel, and the SO2 limit at United Taconite Line 2. The SO2 limits will apply only when the lines 

are burning those primary fuels, not during the use of back up fuels, such as fuel oil. These backup fuels 

are subject to a general state limit and are not significant fuel sources for the facilities. 

The MPCA believes that the scrubbers for lines burning low-sulfur fuels are already optimized for SO2

removal. In general, the SO2 limits are set using existing data and a 95% predictive interval. For lines that 

burn solid fuels, more data is needed to determine if the PM scrubbers can be further optimized to 

improve SO2 removal. 

SO2 BART emission limits, for these lines where sufficient information exists to establish a limit, are 

summarized in Table 9.6 and will be included in the Title V operating permit for each source during the 

next re-opening of the permit, after EPA SIP approval. 

The MPCA has issued Administrative Orders to each of the subject-to-BART taconite sources requiring 

the source to install Continuous Emissions Monitoring Systems (CEMs) or to demonstrate a comparable 

method of emission estimation, and to provide the MPCA with data from these new emission estimation 

methods. The MPCA anticipates that a year of data will be necessary in order to determine the remaining 

BART emission limits for the taconite facilities.59

The comparable alternative method requires a minimum of 150 one-hour data points collected under 

varying furnace conditions. Should emissions be of low variability, the facility is to develop an emission 

factor based on the process parameters. Frequent (annual or bi-annual) stack testing will be required, 

along with submission of quarterly parameters showing continued operation of the furnace under the 

conditions tested. Should emissions be highly variable, facilities must develop a predictive equation to 

correlate emissions with other process parameters. The requirement for more accurate data collection 

through CEMs or a comparable alternative applies to NOX emissions at all the facilities and to SO2

emissions at facilities burning high sulfur fuels. The MPCA will use the emissions and operating data 

gathered to establish BART limits and will include those limits in each facility’s Title V operating permit. 

 

59 Due to economic conditions, many of the taconite lines have not been operating over the past several months. 

This will impact when the MPCA is able to obtain of year of operation data. At this time, we believe many of the 

lines will be starting up during Fall 2009; thus, a full year of data should be obtained by the end of 2010 or early 

2011. 
74 

Administrative Orders by Consent were developed and signed between September 2007 and April 2009. 

US Steel signed Administrative Orders requiring CEMs for its two facilities, Minntac and Keetac. United 

Taconite has also signed an Order to install NOX CEMs and provide NOX data to the MPCA.60 Hibbing 

Taconite, Northshore Mining, and Arcelor Mittal have agreed to and signed Administrative Orders 

requiring the use of a comparable emission estimation method for their facilities. These Orders are 

included in Appendix 9.7. 

In weighing the five factors, MPCA has determined that BART does not result in the installation of any 

new controls or other additional work practice standards or limits for the non-pellet furnace emission 

units primarily because the units are low emitters and thus have negligible impact on visibility. 

The MPCA is unable at this time to quantify the degree of emission reductions resulting from BART, but 

will do so in the Five Year SIP Assessment and revision. 

BART Alternative 

In discussing BART with various facilities, it has come to the MPCA’s attention that some facilities with 

subject-to-BART sources may be considering projects that could result in greater overall emissions 

reductions than would be obtained through installation of BART. 

In October 2006, EPA finalized a rule called Revisions to Provisions Governing Alternative to SourceSpecific Best Available Retrofit Technology (BART) Determinations.

61 The preamble to this rule says, 

“The Regional Haze Rule provides States with the authority to implement...alternative 

measures in lieu of meeting the requirements for source-by-source BART. Under this 

provision of the Regional Haze Rule, States have the flexibility to design programs to 

reduce emissions from stationary sources in a more cost-effective manner so long as they 

can demonstrate that the alternative approach will achieve greater reasonable progress 

towards improving visibility than would have been achieved by implementation of the 

BART requirements...[T]he emissions reductions that could be achieved through 

implementation of the BART provisions at section 51.308(e)(1) serve as the benchmark 

against which States can compare an alternative...”62

The MPCA believes that certain voluntary projects at individual facilities could satisfy this BART 

alternative requirement, with the MPCA’s BART determination serving as the benchmark that must be 

met or exceeded. Should emission reductions of SO2 or NOX result from the proposed projects, the 

MPCA would evaluate these projects in comparison to the BART determinations to see if they result in 

greater control of visibility impairing pollutants than would be expected under BART. 

Due to questions raised during discussion of MPCA’s BART determinations and the opportunity to 

propose an alternative, this section elaborates what the MPCA would consider as acceptable BART 

alternatives, subject to EPA approval of Minnesota’s Regional Haze SIP and BART determinations. 

 

60 Through a stipulation agreement, United Taconite has agreed to install NOX and SO2 CEMS on both Line 1 and 

Line 2. CEMS at Line 2 were installed in January 2009 and must be certified by October 1, 2009; Line 1 has been 

shut down since November 2008, so the CEMS must be installed and certified by 60 days after the line is restarted. 61 71 FR 60612 

62 71 FR 60614. 
75 

A facility may choose to propose a BART alternative project. The BART alternative must result in 

equivalent or greater emissions reductions and visibility benefits from the facility when compared to the 

MPCA’s BART determination. 

Should a facility choose to propose a BART alternative, the proposal must include: 

• A demonstration of equivalent or greater combined annual emission reductions of NOX and SO2

(in tpy) than that established in this BART determination; 

• Appropriate visibility modeling demonstrating equivalent or greater visibility protection than the 

MPCA’s BART determination; and 

• A proposal for enforceable emission limitations, with appropriate and justified averaging periods 

and methods for evaluating compliance. 

Since the facility would be proposing an alternative to MPCA’s BART determination, visibility modeling 

should follow the MPCA’s Guidance for Facilities Conducting a BART Analysis63 and Best Available 

Retrofit Technology (BART) Modeling Protocol to Determine Sources Subject-to-BART in the State of 

Minnesota,64 using the most recent versions of any model or EPA guidance referenced in those 

documents. The modeling should compare the baseline, pre-control scenario to post-control scenarios 

representing the MPCA’s BART determination and the BART alternative being proposed by the facility. 

Facilities may propose a BART alternative that covers multiple BART units or both BART and nonBART units at the facility in the same source category. A proposal covering BART and non-BART units 

must demonstrate greater emission reductions and more visibility improvement from the facility than 

MPCA’s BART determination. 

The MPCA would evaluate the BART alternative proposal, consult with the Federal Land Managers and 

Tribes, and determine if it is an acceptable BART alternative. If the project is deemed to result in 

equivalent or greater pollution control than BART, the MPCA may determine that the proposed project is 

equivalent to BART. The resulting emission limits would then substitute for the BART emission limits. 

Ultimately, EPA approval of an enforceable document (such as a Title V permit) containing BART 

emission limits will be necessary. 

BART Implementation 

Minnesota is requiring that each subject-to-BART source, whether EGU or taconite facility, to install and 

operate BART as expeditiously as practicable but in no event later than five years after approval of the 

SIP or plan revision by EPA. Although at this time the exact BART emission limits for all the taconite 

furnaces have yet to be determined, BART implementation and compliance will still occur within the 

required five-year time frame. 

The MPCA has an established procedure, approved by EPA Region 5, for including SIP conditions in 

Title V permits. The permits then become joint Title I/Title V documents, and any conditions imposed on 

the individual facilities to meet SIP requirements are cited as “Title I Condition: SIP for <pollutant>.” 

Title I conditions in Minnesota permits never expire. 

Whether the final BART is good combustion practices measured by CEMs or more accurate emission 

measurements, or if another project that provides greater emission reductions is chosen to substitute for 

BART, any resulting emissions limits will be placed in the facility’s Title V permit. The MPCA is likely 

to include BART limits in Title V permits with the citation “Title I Condition: SIP for Regional Haze.” 

 

63 http://www.pca.state.mn.us/publications/aq-sip2-09.pdf 

64 http://www.pca.state.mn.us/publications/aq-sip2-05.pdf 
76 

The Title V operating permits also will include a requirement that each source maintain any necessary 

control equipment and establish procedures to ensure such equipment is properly operated and 

maintained. Minnesota intends to include these Title V operating permits in the Five Year SIP 

Assessment and revision. 
Table 9.6: SO2 BART Determinations for Units Where a Full BART Analysis Was Conducted 

Facility Name ID Title V Permit # 

Emission 

Unit # 

Emission 

Unit 

Description 

SO2 Baseline

Emissions 

Used in Cost 

Analysis 

(tpy) 

Capacity65 Baseline 

Controls 

SO2 Max. 24-

Hr Actual 

Emissions 

Reported 

(lb/day) 

BART BART

Emission 

Limit 

(30-day rolling 

average)

Keetac 2713700063 # 13700063-003 

EU030 Pellet Furnace 950.5 93% 

Recirculating lime scrubber for PM/SO2

control 

9600 

Existing (2005) recirculating lime scrubber 

TBD after gathering emissions/ scrubber parameter data 

Ain3

Hibbing Taconite 2713700061 #13700061-002

EU020 

Pellet Furnace Line 1 

202.2 93% Wet scrubber for PM control 720 Existing PM wet scrubber 0.207 lb SO2/long ton pellet fired 

Loof re

EU021 

Pellet Furnace Line 2 

179.5 93% Wet scrubber for PM control 912 Existing PM wet scrubber 0.207 lb SO2/long ton pellet fired 

Loof re

EU022 

Pellet Furnace Line 3 

188.1 93% Wet scrubber for PM control 1,032 Existing PM wet scrubber 0.207 lb SO2/long ton pellet fired 

Loof re

Minntac 2713700005 #13700005-002 

EU223 Line 3 329.3 93% Recirculating scrubber 2366 

Existing recirculating scrubber (installed 2006)

116 lbs SO2/hour 

Loof re

EU259 Line 4 447.5 93% Wet scrubber for PM control 3511 Existing wet scrubber 180 lbs SO2/hour 

Loof re

EU280 Line 5 447.5 93% Wet scrubber for PM control 3511 Existing wet scrubber 180 lbs SO2/hour 

Loof re

EU313 Line 6 544.8 93% Wet scrubber for PM control 4435 Existing wet scrubber TBD after gathering emissions/ scrubber parameter data A

in

2

65 Capacity figures comes from expected capacity utilization described in the facilities’ BART analyses. 
Facility Name ID Title V Permit # 

Emission 

Unit # 

Emission 

Unit 

Description 

SO2 Baseline

Emissions 

Used in Cost 

Analysis 

(tpy) 

Capacity65 Baseline 

Controls 

SO2 Max. 24-

Hr Actual 

Emissions 

Reported 

(lb/day) 

BART BART

Emission 

Limit 

(30-day rolling 

average)

EU332 Line 7 544.8 93% Wet scrubber for PM control 4435 Existing wet scrubber TBD after gathering emissions/ scrubber parameter data A

in

2

United Taconite 2713700113 #13700113-004 

EU040 Line 1 13.9 93% Wet scrubber for PM control 100.8 Existing wet scrubber 0.121 lb SO2/long ton pellet fired 

C

afto o

e

EU042 Line 2 2749.7 93% Wet scrubber for PM control 15,173 Fuel blending 1.7 lbs/MMBtu 

C

1Tap

ArcelorMittal 2713700062 #13700062-002 

EU026 

Pellet furnace SV014 

44.8 93% Wet scrubber for PM control 3000 Existing wet scrubber 0.165 lb SO2/long ton 

pellet fired Facility has one furnace with four stacks; the emission limit is based on the sum of emissions from all four stacks. 

Loof re

EU026 

Pellet furnace SV015 

44.8 93% Wet scrubber for PM control 3000 Existing wet scrubber 

EU026 

Pellet furnace SV016 

44.8 93% Wet scrubber for PM control 3000 Existing wet scrubber 

EU026 

Pellet furnace SV017 

44.8 93% Wet scrubber for PM control 3000 Existing wet scrubber 

Northshore Mining 2707500003 #07500003-004 

EU003 Process Boiler #1 73.4 100% (0% in past practice) Permit allows only NG/ distillate fuel burned 403.8 No additional control None needed NEU004 Process Boiler #2 73.4 100% (0% in past practice) Permit allows only NG/ distillate fuel burned 403.8 No additional control None needed N
Facility Name ID Title V Permit # 

Emission 

Unit # 

Emission 

Unit 

Description 

SO2 Baseline

Emissions 

Used in Cost 

Analysis 

(tpy) 

Capacity65 Baseline 

Controls 

SO2 Max. 24-

Hr Actual 

Emissions 

Reported 

(lb/day) 

BART BART

Emission 

Limit 

(30-day rolling 

average)

Northshore Mining 2707500003 # 07500003-004 

EU100 

Furnace 11 Hood Exhaust 

28.6 93% Wet-Wall ESP for PM control 852 Existing wet- wall ESP 

0.0651 lb SO2/long ton 

pellet fired for EU100/EU104 combined 

Loof re

EU104 Furnace 11 Waste Gas 9.6 93% Wet-Wall ESP for PM control 283.2 Existing wet- wall ESP 

0.0651 lb SO2/long ton 

pellet fired for EU100/EU104 combined 

Loof p

EU110 

Furnace 12 Hood Exhaust 

26.3 93% Wet-Wall ESP for PM control 852 Existing wet- wall ESP 0.0651 lb SO2/long ton pellet fired for EU110/ EU114 combined L

oof p

EU114 Furnace 12 Waste Gas 8.8 93% Wet-Wall ESP for PM control 283.2 Existing wet- wall ESP 0.0651 lb SO2/long ton pellet fired for EU110/ EU114 combined L

oof p
Table 9.7: NOX BART Determinations for Units Where a Full BART Analysis Was Conducted 

Facility Name ID Title V Permit # 

Emission 

Unit 

Number 

Emission 

Unit 

Description 

NOx Baseline

Emissions 

Used in Cost 

Analysis 

(tpy) 

Capacity66 Baseline 

Controls 

NOx Max. 24-

hr Actual 

Emissions 

Reported 

(lb/day) 

BART BART

Emission 

Limit 

(30-day rolling 

average) 

Keetac 2713700063 #13700063-003 

EU030 Pellet Furnace 4154 93% None 33,520 Good combustion practices, fuel blending TBD after gathering sufficient emissions data 

Hibbing Taconite 2713700061 #13700061- 002

EU020 

Pellet Furnace Line 1 

2497.7 93% None 13,392 

Good combustion practices, furnace energy efficiency project made in 2006 

TBD after gathering sufficient emissions data 

EU021 

Pellet Furnace Line 2 

2143.5 93% None 11,112 

Good combustion practices, furnace energy efficiency project made in 2006 

TBD after gathering sufficient emissions data 

EU022 

Pellet Furnace Line 3 

2247.1 93% None 12,624 

Good combustion practices, furnace energy efficiency project made in 2007 

TBD after gathering sufficient emissions data 

Minntac 2713700005 # 13700005-002 

EU223 Line 3 1345 93% None 21,046 

Good combustion practices, fuel blending 

TBD after gathering sufficient emissions data 

EU259 Line 4 1812 93% None 32,472 

Good combustion practices, fuel blending, low NOX

burners in pre-heat zone 

TBD after gathering sufficient emissions data 

EU280 Line 5 1820 93% None 32,472 

Good combustion practices, fuel blending, low NOX

burners in pre-heat zone 

TBD after gathering sufficient emissions data 

66 Capacity figures comes from expected capacity utilization described in the facilities’ BART analyses. 
Facility Name ID Title V Permit # 

Emission 

Unit 

Number 

Emission 

Unit 

Description 

NOx Baseline

Emissions 

Used in Cost 

Analysis 

(tpy) 

Capacity66 Baseline 

Controls 

NOx Max. 24-

hr Actual 

Emissions 

Reported 

(lb/day) 

BART BART

Emission 

Limit 

(30-day rolling 

average) 

EU313 Line 6 1776 93% None 28,855 

Good combustion practices, fuel blending, low NOX

burners in pre-heat zone 

TBD after gathering sufficient emissions data 

EU332 Line 7 1928 93% None 28,855 

Good combustion practices, fuel blending, low NOX

burners in pre-heat zone 

TBD after gathering sufficient emissions data 

United Taconite 2713700113 #13700113-004 

EU040 Line 1 2151 93% None 15,631 

Good combustion practices, past heat recuperation project 

TBD after gathering sufficient emissions data 

EU042 Line 2 1633 93% None 9,005 

Good combustion practices, fuel blending; further evaluation of Ported Kilns needed. 

TBD after gathering sufficient emissions data 

ArcelorMittal 2713700062 #13700062-002 

EU026 

Pellet furnace SV014 

369.6 93% 

None 

3730 

Good combustion practices and furnace energy efficiency project completed in fall ’07, low NOX

burner in furnace pre-heat zone. 

TBD after gathering sufficient emissions data. 

EU026 

Pellet furnace SV015 

669 93% 4800 

EU026 

Pellet furnace SV016 

1031 93% 7399 

EU026 

Pellet furnace SV017 1419 93% 10,183 

Northshore Mining EU003 

Process Boiler #1 (back-up) 

50.9 

100% (0% in past practice) 

None 278.4 No additional control None needed 
Facility Name ID Title V Permit # 

Emission 

Unit 

Number 

Emission 

Unit 

Description 

NOx Baseline

Emissions 

Used in Cost 

Analysis 

(tpy) 

Capacity66 Baseline 

Controls 

NOx Max. 24-

hr Actual 

Emissions 

Reported 

(lb/day) 

BART BART

Emission 

Limit 

(30-day rolling 

average) 

2707500003 # 07500003-004 

EU004 

Process Boiler #2 (back-up) 

50.9 

100% (0% in past practice) 

None 278.4 No additional control None needed 

EU100 

Furnace 11 Hood Exhaust 

112.4 93% None 1231.2 Good combustion practices TBD after gathering sufficient emissions data 

EU104 Furnace 11 Waste Gas 273.7 93% None 2995.2 Good combustion practices TBD after gathering sufficient emissions data EU110 

Furnace 12 Hood Exhaust 

109.9 93% None 1231.2 Good combustion practices TBD after gathering sufficient emissions data 

EU114 Furnace 12 Waste Gas 267.7 93% None 2995.2 Good combustion practices 

TBD after gathering sufficient emissions data 
83 

Chapter 10. Reasonable Progress Goals and Long-Term Strategy

The requirements of 40 CFR 51.308(d)(1) call for Minnesota to establish a Reasonable Progress Goal 

(RPG) for each Class I area within the state. The RPG, expressed in deciviews, ensures the state is 

making progress towards achieving natural visibility. Over the SIP period, the goals must provide for 

improvement in visibility over the most impaired days, and ensure no degradation in visibility over the 

least impaired days. The state must also provide an assessment of when the Class I areas would attain 

natural visibility conditions if improvement continues at the rate represented by the RPG. 

In addition, 40 CFR 51.308(d)(3) requires states to submit a long-term strategy (LTS) addressing regional 

haze for each mandatory Class I area which may be affected by emissions from within the state. The LTS 

must include enforceable emissions limitations, compliance schedules and other measures necessary to 

achieve the RPG established by the state in which the Class I area is located for both best and worst 

visibility days. 

This chapter contains Minnesota’s long-term strategy for implementing all known reasonable control 

measures in order to ensure the RPG is met at all Class I areas to which Minnesota’s emissions are a 

significant contributor to visibility impairment. It also includes the reasonable progress goals established 

by Minnesota for BWCAW and VNP. 

Consultation 

Minnesota must consult with other states and tribes to set the RPG and develop coordinated emission 

strategies for meeting the established RPG. This requirement applies both where emissions from 

Minnesota are reasonably anticipated to contribute to visibility impairment in Class I areas outside the 

state and where emissions from other states and tribes are reasonably anticipated to contribute to visibility 

impairment in Minnesota’s Class I areas. 

Minnesota consulted with other states and tribes in several ways, including participation in CENRAP and 

the Northern Class I consultation processes, in order to develop the technical information necessary for 

determining where each state’s emissions are reasonably anticipated to contribute to visibility 

impairment, as well as information about the URP, implementation of coordinated emission strategies, 

and the RPG. These consultation processes are documented in Chapter 3. The state’s coordination with 

FLMs is described in Chapter 4. 

Basis for emission reduction obligations 

Minnesota is required to demonstrate that its implementation plan includes all measures necessary to 

obtain its fair share of emission reductions needed to meet reasonable progress goals at all Class I areas 

where visibility is impacted by emissions from Minnesota sources (40 CFR 51.308(d)(3)(ii)). 

Determining that fair share of emission reduction requires knowledge of which Class I areas are most 

impacted by emissions from Minnesota, and which states’ emissions most impact visibility in 

Minnesota’s Class I areas. This section documents the technical basis for Minnesota’s apportionment of 

emission reductions, both to meet the RPG in Minnesota’s Class I areas and to meet the RPG in any Class 

I area impacted by Minnesota emissions. 

Minnesota relied in part on technical analyses developed by MRPO and CENRAP to demonstrate that the 

state’s emission reductions, when coordinated with those of other states, are sufficient to achieve all 

reasonable progress goals. In cooperation with the Northern Class I consultation group and using the 

aforementioned technical analyses, as well as analyses and modeling done in-house, the MPCA went 

through the following steps to determine Minnesota’s contribution to visibility impairment at various 
84 

Class I areas, which forms the basis for Minnesota’s emission reduction obligations. (Documentation of 

the various steps is in the listed appendices.) 

Baseline inventory 

Minnesota assessed the RPG and developed its long-term strategy using emission inventories developed 

by MRPO, with some Minnesota specific changes.67 See Chapter 8 for further information. 

Minnesota’s Impact on Class I areas 

Minnesota is reasonably anticipated to significantly contribute to visibility impairment at three of the four 

Northern Class I areas: BWCAW, VNP, and Isle Royale. Initial modeling and data analysis studies done 

by MRPO showed that Minnesota was expected to contribute 30 – 35% of the visibility impairment 

affecting its own Class I areas in 2018, and about 14% of the visibility impairment affecting Isle Royale. 

Using the MPCA’s determination that a significant contribution to visibility impairment is a contribution 

over five percent on the worst days, Minnesota is not expected to significantly contribute to visibility 

impairment at any other Class I areas. Although Minnesota contributes five percent to overall visibility 

impairment at the fourth Northern Class I area, Seney Wilderness, Minnesota’s contribution on the worst 

visibility days is below the five percent threshold and therefore is not further discussed. 

Minnesota’s own modeling analysis, described in Chapter 8, supports the conclusions drawn in the initial 

modeling and data analysis done by MRPO. Based on the MPCA’s modeling, Minnesota has the 

following contributions to light extinction in 2018 at BWCAW, VNP, and Isle Royale: 

Table 10.1: Class I areas Impacted by Minnesota 

Class I area Minnesota Contribution to Light 

Extinction68 in 2018 

BWCAW 28% 

VNP 31% 

Isle Royale 13% 

CENRAP constructed Areas of Influence (AOIs) for each of its Class I areas, showing the important 

upwind source areas for emissions of precursors to visibility impairing pollutants. The AOIs show that 

Minnesota is in the Level 1 AOI (the AOI with the most impact) for the two Minnesota Class I areas, with 

small areas of the state in the Level 1 AOI for nitrate for the Class I areas in Missouri and Arkansas and in 

the sulfate and nitrate AOIs for the Class I areas in North and South Dakota.69 However, CENRAP’s 

PSAT analysis indicates Minnesota is not a significant contributor to these Class I areas, based on 

MPCA’s chosen five percent threshold. (See Appendix 10.1) 

Oklahoma identified Minnesota as a state that contributes to visibility impairment in the Wichita 

Mountains Class I area, using CENRAP’s PSAT analysis and a threshold of one inverse megameter 

contribution in 2018. However, Oklahoma did not identify any particular control measures that 

Minnesota was expected to undertake, due to the fact that Minnesota’s contribution was equivalent to the 

threshold level. 

The contribution assessment performed by Northeast States for Coordinated Air Use Management 

(NESCAUM) for the Mid-Atlantic/Northeast Visibility Union (MANE-VU) shows Minnesota 

contributing less than one percent of the sulfate impact at the Mid-Atlantic and Northeast Class I areas.70 

 

67 MRPO, 2006. 

68 This shows only light extinction resulting from nitrate, sulfate, and ammonium. 

69 Stella, G.M et al., 2006. 

70 NESCAUM, 2006. 
85 

CENRAP’s PSAT analysis shows that Minnesota contributes less than 3.5% of modeled light extinction 

to the MANE-VU Class I areas on the 20% worst days in 2018. Minnesota was not identified by MANEVU as a state impacting its Class I areas.71

Back trajectory analysis by the Visibility Improvement State and Tribal Association of the Southeast 

(VISTAS) shows that some air masses impacting various Class I areas in Virginia, North Carolina, and 

Florida may have had some residence time over Minnesota, but it does not appear substantial enough to 

make Minnesota a significant contributor to those Class I areas.72 CENRAP’s PSAT analysis shows that 

Minnesota contributes less than two percent of modeled light extinction to the VISTAS Class I areas on 

the 20% worst days in 2018. (See Appendix 10.1). 

No states other than Michigan and Oklahoma have, at this time, formally asked Minnesota to consult with 

them as a significant contributor to visibility impairment at their Class I areas. Neither state has asked 

Minnesota to undertake specific emission reductions. 

Because Minnesota is the major contributor to its own Class I areas, the MPCA believes that the measures 

undertaken to reach the RPG set for BWCAW and VNP will be sufficient to account for its share of 

emission reductions needed to meet the RPG at any other Class I areas that Minnesota may impact, 

particularly Isle Royale. 

States Impacting Minnesota’s Class I areas 

Minnesota identified the states expected to contribute significantly to visibility degradation, defined as 

more than five percent of visibility impairment on the worst days, in both VNP and BWCAW using the 

MRPO’s initial 2018 PSAT analysis, without later modifications (i.e., inclusion of IPM version 3.0 for 

EGUs.). Based on this information, the states identified as contributing to visibility impairment in 

Minnesota’s Class I areas are: Minnesota, Wisconsin, Illinois, Iowa, Missouri, and North Dakota. 

Appendix 3.2, containing Minnesota’s consultation letter, gives further information and shows that other 

analyses by MRPO and CENRAP support the determination of the contributing states. 

Subsequent analyses by Minnesota, using in-house modeling, show that the impacts of the contributing 

states on BWCAW, VNP, and Isle Royale are as follows: 

Table 10.2: Percentage Contributions by State to Light Extinction73

 BWCAW VNP Isle Royale74

Minnesota 28% 31% 13% 

Wisconsin 10% 6% 16% 

Illinois 6% 3% 8% 

Iowa 8% 7% 8% 

Missouri 6% 4% 5% 

North Dakota 6% 13% 4% 

Further information can be found in Appendices 3.1, 3.2 and 10.1, Chapter 8, and the Technical Support 

Document. 

 

71 MANE-VU, Inter-RPO Consultation Briefing Book. (webpage) 72 VISTAS. Summary Materials: Summary Presentations for each Class I area. (webpage) 73 Again, this shown only light extinction resulting from sulfate, nitrate, and ammonium. 

74 This indicates contributions shown at the western tip of the island of Isle Royale, which is closest to Minnesota, 

not the IMPROVE monitor location, which is on the mainland. 
86 

Pollutants and Sources Impacting Minnesota’s Class I areas 

The pollutants predicted to contribute most to visibility impairment in each Class I area on the 20% worst 

days, both in the baseline period and in 2018, are sulfate, nitrate, and primary organic carbon. (See 

Figure 10.3.) MPCA chose to focus on sulfate and nitrate, as primary organic carbon appears to be at 

levels close to those estimated as natural condition levels and is a smaller contributor to light extinction. 

Also, the main sources of organic carbon seen in the Northern Class I areas are primarily biogenic in 

origin. Organic carbon is treated further in the section on fires and smoke emissions. More information 

on visibility impairing pollutants can be found in Appendices 3.1, 10.1, Chapter 8 and the TSD. 

Figure 10.3: 2002 Observations and 2018 Projections in Extinction by Species W20% Days 

BWCAW VNP 

 

MPCA also identified the major sources of the pollutants likely to contribute to visibility degradation in 

each Class I area in 2018. Figure 10.4 documents the major sources of NOX and SO2 emissions (in tons 

per year) in 2002 and 2018. Point sources are clearly a key source of emissions. 

Figure 10.4: NOX and SO2 Emissions in Minnesota by Source Category 

0

10

20

30

40

50

60

70

80

Observed Projected 2018

Average

Extinction (Mm-1)

CM

CRUSTAL

EC

OC

NO3

SO4

0

100000

200000

300000

400000

500000

600000

2002 2018 2002 2018

Year

Emissions (tpy)

Point

Biogenics

Area

Non-Road

Mobile

NOX SO2

0

10

20

30

40

50

60

70

80

Observed Projected 2018

Average

Extinction (Mm-1)

CM

CRUSTAL

EC

OC

NO3

SO4
87 

Figures 10.5 and 10.6 show the main source categories contributing to light extinction from sulfate, 

nitrate, and ammonium in BWCAW and VNP. The major contributing sources in 2018 are projected to 

be EGUs. EGUs remain a large percentage contributor in 2018, as they were in 2002, partially due to 

major projected reductions in nonroad and onroad emissions. More information can be found in 

Appendices 3.1 and 10.1, along with Chapter 8 and the TSD. 

Figure 10.5: BWCAW 2018 Extinction by Sector for each Specie, W20% Days 

Figure 10.6: VNP 2018 Extinction by Sector for each Specie, W20% Days 

These figures, along with Chapter 8 and the modeling TSD, document the anthropogenic sources of 

visibility impairment considered by the state in developing its long-term strategy, as required by 40 CFR 

51.308(d)(3)(iv). More detailed discussion of the pollutants and source categories considered can be 

found in Chapter 8. 

0

2

4

6

8

10

12

14

16

18

20

22

PSO4 PNO3 PNH4 ASOA BSOA

Extinction (Mm-1)

EGU nonEGU Onroad Nonroad otherArea Ammonia BC ASOA BSOA

Total Extinction:

 35 Mm-1 

0

2

4

6

8

10

12

14

16

18

20

22

PSO4 PNO3 PNH4 BSOA ASOA

Extinction (Mm-1)

EGU nonEGU Onroad Nonroad otherArea Ammonia BC ASOA BSOA

Total Extinction:

 34 Mm-1 
88 

Guidance in Determining RPG 

EPA released final guidance on June 1, 2007 to use in setting RPGs.75 The EPA guidance states: 

“RPGs are interim goals that represent incremental visibility improvement over time toward 

the goal of natural background conditions and are developed in consultation with other 

affected states and Federal Land Managers (FLMs). In determining what would constitute 

reasonable progress, section 169A(g) of the CAA requires states to consider the following 

four factors: 

• The costs of compliance; 

• The time necessary for compliance; 

• The energy and non-air quality environmental impacts of compliance; and 

• The remaining useful life of existing sources that contribute to visibility 

impairment. 

States must demonstrate in their SIPs how these factors are taken into consideration in 

selecting the RPG for each Class I area in the state...As noted above, the RHR establishes 

an additional analytical requirement for states in the process of establishing the RPG. This 

analytical requirement requires states to determine the rate of improvement in visibility 

needed to reach natural conditions by 2064, and to set each RPG taking this ‘glidepath’ into 

account...EPA adopted this approach, in part, to ensure that states use a common analytical 

framework that accounts for the regional difference affecting visibility and, in part, to 

ensure an informed and equitable decision making process. The glidepath is not a 

presumptive target, and states may establish a RPG that provides for greater, lesser, or 

equivalent visibility improvement as that described by the glidepath.” 

The glidepath named in the EPA guidance, also called the “Uniform Rate of Progress” (URP) is 

essentially a line between current or baseline conditions on the worst days and natural background in 

2064. (See Chapter 5) The URP requires 0.12 deciviews of improvement annually at VNP and 0.14 

deciviews annually at BWCAW to meet natural conditions by 2064. The tables in Chapter 5 give 

additional information about the observed visibility conditions. 

Approach to Determining RPG76

The following approach was used to determine the RPG for the four Northern Class I areas. It was 

developed by MRPO based on EPA’s draft guidance for setting reasonable progress goals, and agreed to 

by the states involved in the Northern Class I consultation process. By the time of the publication of 

EPA’s final reasonable progress guidance, the states in the Northern Class I consultation process were 

already acting based on the draft guidance, and Minnesota did not feel that the changes to the guidance 

were substantive enough to warrant changes to the RPG approach. 

The states involved in the Northern Class I consultation process worked together to identify and prioritize 

sources, assess the impact of existing control programs on priority sources, and to direct a contract to 

investigate and evaluate control options for those priority sources. MPCA then followed this basic 

approach in setting the RPGs for Minnesota. The basic steps for determining the RPG were as follows: 

Identify and Prioritize Sources: The first step was to determine existing visibility conditions, examine 

which sources and geographic regions are contributing to worst and best visibility days, and, with the help 

of air quality models and monitoring receptor analyses, identify the major anthropogenic sources/sectors 

contributing to worst visibility days (priority sources) and their relative impacts on visibility impairment. 

 

75 U.S. EPA, OAQPS, 2007b. 

76 MRPO, 2005c. 
89 

Overall, the states comprising the Northern Class I areas consultation group agreed that the priority 

emissions and sources were: 

• SO2 from point sources (EGUs and non-EGUs) 

• NOX from point sources (EGUs and non-EGUs) and mobile sources 

• NH3 from agricultural operations 

MPCA determined that the major pollutant and source impacting Minnesota’s Class I areas appears to be 

SO2 from EGU, which forms ammonium sulfate. Modeling shows that sulfate is one of the main 

components of haze at VNP, BWCAW, and Isle Royale on the 20% worst days. (See Appendix 3.1 and 

Chapter 8). EGU SO2 emissions from Minnesota, Wisconsin, Iowa, North Dakota, Missouri and Illinois 

appear to be the key contributors. Ammonium nitrate is also an important anthropogenic contributor to 

visibility impairment. 

MPCA also identified the Northeastern corner of the state, the six counties closest to the Class I areas, as 

an important source area of SO2 and NOX emissions. MPCA reviewed control strategy analyses done by 

CENRAP, which identified natural gas compressor stations and industrial, commercial and institutional 

(ICI) boilers as priority sources that should be evaluated for potential control, and also identified 

potentially low cost control measures for multiple sources. 

Identify Control Options for Priority Sources: The second step was to develop control options for 

reducing the emissions from the priority sources, including existing and expected control programs (e.g., 

CAIR, BART, and nonattainment area controls) and other possible control programs. Minnesota worked 

in conjunction with MRPO to fund a contract to examine various control strategies. (See Appendix 10.5.) 

On the books control measures examined were: 

• Clean Air Interstate Rule 

• BART 

• MACT 

o Reciprocal Internal Combustion Engines 

o Industrial Boilers and Process Heaters 

• On-Road Mobile Source Programs 

o 2007 Highway Diesel Rule 

o Tier II/Low Sulfur Gasoline 

• Non-road mobile source programs 

o Non-road Diesel Rule 

o Control of Emissions from Unregulated Non-road Engines 

• Locomotive/Marine 

The other control options or scenarios examined, developed by MRPO, were the following: 

• EGU control scenarios setting regional emission limits based on 

o EGU1: SO2 limits of 0.15 lbs/MMBtu 

NOX limits of 0.10 lbs/MMBtu 

o EGU2: SO2 limits of 0.10 lbs/MMBtu 

NOX limits of 0.07 lbs/MMBtu 

• ICI Boilers 

o ICI1: SO2 reduction of 40% from 2018 baseline 

 NOX reduction of 60% from 2018 baseline 

o MRPO Workgroup Proposal resulting in approximately a 77% reduction in SO2 and 70% 

in NOX. 
90 

In Minnesota, the majority of the EGUs whose emissions significantly impact BWCAW and VNP are 

already undertaking controls and/or will be subject to BART limits. MPCA also identified the indurating 

furnaces used in taconite pellet production in Northeastern Minnesota as priority sources. These furnaces 

are subject to BART, but few emission reduction options for SO2 or NOX have been investigated and are 

known to be reasonable. 

Control options for various other sources were investigated in the EC/R report for MRPO and MPCA, 

shown in Appendix 10.5, and by Alpine Geophysics for CENRAP, shown in Appendix 10.6. This 

includes control measures and projected costs of control for natural gas compressor stations and ICI 

boilers and other sources identified by CENRAP. Rather than identifying specific emission limits for 

these sources, incremental control options (above and beyond the 2018 base case) were identified and 

grouped by cost and emission reductions achieved.77 See Appendix 10.6 for further information. 

Finally, Minnesota identified control options for its priority sources in Northeastern Minnesota, as 

described later in this Chapter. 

Assess Effect of Existing Programs for Priority Sources: The third step was to assess the expected 

emission reduction from existing control programs for the priority sources, especially for the important 

visibility impairing pollutants (e.g., SO2 and NOX). Minnesota will obtain emission reductions from some 

of these priority sources under existing and on the books programs. The impact of existing programs is 

described below, in the long-term strategy section on “Emission reductions due to ongoing air pollution 

programs.” In addition, the EC/R report describes the expected emission reductions that will occur 

regionally from on the books controls for priority sources. 

Evaluate Control Options for Priority Sources: Using the four statutory factors, the next step was to 

evaluate the control options for all priority sources and determine which measures may be reasonable. 

Many control options for priority sources were evaluated in the report in Appendix 10.5. Particular 

attention was paid in the Northern Class I consultation group to the “EGU1” control strategy proposed by 

MRPO, which is a 0.15 lb/MMBtu SO2 limit and a 0.10 lb/MMBtu NOX limit assumed to take effect in 

2013. Many in the Northern Class I consultation group also believe it is important to take a look at ICI 

boilers, and the control strategies proposed by MRPO for those sources, including a 40% reduction in 

SO2 limit and a 60% reduction NOX by 2013. 

CENRAP evaluated control options for all sources that met the so-called Q/5D criteria, i.e. that their level 

of emissions (in tons) when divided by their distance (in kilometers) from an affected Class I area was 

less than or equal to five, and focused on control options that were available for less than $5000/ton. 

CENRAP’s analysis indicates that, from sources meeting the Q/5D and less than $5000/ton criteria, 

Minnesota could reduce 8192 tons of NOX emissions from the 2002 baseline at an average cost per ton 

between $2000 and $2500. This analysis did not find any SO2 emission reductions available matching the 

specified criteria. Many of the NOX reductions were found at facilities that are already undertaking 

emission controls. 

Because of the lack of known control options for taconite indurating furnaces, MPCA chose to include 

these sources in a regional approach to emission reductions, which is described as part of the long-term 

strategy. See “Plan for Emission Reductions in Northeast Minnesota.” Part of the goal of this plan is to 

spur the development of new control options. 

 

77 Stella, February and March 2007. 
91 

The states in the Northern Class I consultation process have largely agreed on the priority pollutants (SO2

and NOX) and sources (EGU, and to a lesser extent ICI boilers), with each state adding some specific 

priority sources or source categories. 

Compare Control Strategies with Uniform Rate of Progress: The final step was to compute the 

appropriate visibility metrics for the existing/expected controls and the “reasonable” controls for the Class 

I areas. Compare the expected improvement in visibility with the 60-year glidepath to natural conditions, 

and determine when areas would meet natural conditions if the annual progress under the RPG is less than 

the URP. 

MPCA included in its long-term strategy all control measures currently believed to be reasonable, and 

modeled these control strategies to determine if the resulting visibility improvement was equivalent to, 

better, or worse than the URP. This is documented in the modeling chapter and will be described in more 

detail later, in the discussion of the RPG. 

Share of Emission Reductions 

Each state must obtain its share of emission reductions needed to attain the RPG. Between now and 

2018, there will be reductions in emissions of SO2 and NOX in Minnesota and the region impacting 

Minnesota’s Class I areas due to on the books control strategies, voluntary projects, and additional 

emission control measures. Many of these additional control strategies have been discussed by the 

Northern Class I consultation group. However, because of the differences in attainment status for criteria 

pollutants and contribution towards haze, each state must ultimately make its own decision as to which 

control measures are reasonable, thereby impacting the reasonable progress goal. 

Many of the states that contribute to visibility impairment in Minnesota’s Class I areas are tackling 

multiple SIP issues at once (haze, PM2.5 and ozone) and will submit their haze SIPs at a future date. 

Therefore, at this time Minnesota is establishing a RPG that might be exceeded due to the controls these 

states develop as they continue to work on their SIPs. 

All of the control measures that Minnesota currently plans to undertake are included in the long-term 

strategy and described in the following section. The MPCA believes this contains all control measures 

currently known to be reasonable. Therefore, the RPG is set at the visibility level shown to result from 

the application of all the elements of Minnesota’s long-term strategy, along with all currently known 

controls being applied by other states. 

The RPG is documented towards the end of this chapter, after discussion of the long-term strategy. 

Minnesota believes that the state’s long-term strategy when coordinated with other state and Tribes’ 

strategies will be sufficient to meet the reasonable progress goals set out below. 

Minnesota’s Long-Term Strategy 

All of the control strategies that will contribute to meeting the RPG are documented in Minnesota’s longterm strategy. MPCA is required by 40 CFR 51.308(d)(3)(v) to consider several factors in developing its 

long-term regional haze strategy. These are discussed below. 

Emission reductions due to ongoing air pollution programs 

40 CFR 51.308(d)(3)(v)(A) requires Minnesota to consider emission reductions from ongoing pollution 

control programs. These emission reductions are reflected in the 2018 modeling inventory. 

Minnesota considered the following ongoing or expected programs in developing its long-term strategy: 
92 

Clean Air Interstate Rule (CAIR)

Minnesota’s electric generating utilities (EGU) were initially covered under the federal Clean Air 

Interstate Rule (CAIR), designed to reduce emissions of nitrogen oxides and sulfur dioxide. However, on 

May 12, 2009, EPA published a proposed rule to stay the effectiveness of CAIR in Minnesota, until EPA 

can determine if Minnesota meets the threshold for inclusion in the CAIR region. If finalized, Minnesota 

EGUs will not have to comply with CAIR until EPA’s repromulgated CAIR rule makes a final ruling on 

Minnesota’s inclusion. CAIR will continue to have an impact on visibility in Minnesota by reducing 

emissions in surrounding states. 

The following table shows predictions of emissions from Midwest EGUs in 2018 using version 3.0 of 

EPA’s IPM modeling, which assumes that CAIR is implemented. 

Table 10.3: IPM 3.0 Predictions for 2018 

State Heat Input 

(MMBtu/year) 

SO2

(tons/year) SO2 (lb/MMBtu) NOx 

(tons/year) NOx (lb/MMBtu) 

IL 1,310,188,544 277,337 0.423 70,378 0.107 

IN 1,509,616,931 361,835 0.479 90,913 0.120 

IA 534,824,314 115,938 0.434 59,994 0.224 

MI 1,009,140,047 244,151 0.484 79,962 0.158 

MN 447,645,758 61,739 0.276 41,550 0.186 

MO 893,454,905 243,684 0.545 72,950 0.163 

ND 342,685,501 41,149 0.240 44,164 0.258 

SD 44,856,223 4,464 0.199 2,548 0.114 

WI 675,863,447 127,930 0.379 56,526 0.167 

Although Minnesota is likely to be removed from the current CAIR program, the MPCA is aware of 

several facility-specific pollution control projects that were being undertaken to ease compliance under 

CAIR; some of these projects will be required to fulfill BART for specific units, others will go forward 

voluntarily. 

Minnesota has also seen a number of voluntary projects being undertaken by EGUs to reduce emissions 

due to Minnesota statute 216B.1692, which makes the cost of environmental projects at existing large 

EGUs eligible for rate recovery. Projects completed or going forward under this statute are underlined in 

the following bulleted list. The statutory language is shown in Appendix 10.2. We believe that IPM 3.0 

remains a relatively accurate portrayal of future EGU emissions in Minnesota, despite the potential 

change in CAIR status. See Chapter 8 for more information. 

The MPCA has considered the following emission reductions in developing Minnesota’s long-term 

strategy; these projects have regulatory certainty as they are either already operating or have submitted 

applications to the Minnesota Public Utilities Commission for rate recovery or permit applications to the 

MPCA.78 Appendix 10.3 contains details on how to access relevant Air Emission Permits for these 

projects. 

The projects being undertaken to reduce NOX and/or SO2 include: 

• Minnesota Power, Boswell – Unit 3 – BACT-like NOX and SO2 controls by 2009

• Minnesota Power, Laskin – Units 1,2 – NOX controls by 2009

 

78 For example, documents relating to Minnesota Power’s application for a emission reduction rider for pollution 

control projects at Laskin and Taconite Harbor can be found at https://www.edockets.state.mn.us/EFiling/search.jsp 

by searching for docket number 05-1678. 
93 

• Minnesota Power, Taconite Harbor – Units 1,2,3 – NOX and SO2 controls by 2009

• Ottertail Power, Hoot Lake – Units 2,3 – NOX controls by 2008 

• Rochester Public Utilities, Silver Lake Plant – Unit 4 – NOX and SO2 controls by 2009 

• Xcel Energy, Allen S. King Plant – Unit 1 – NOX and SO2 controls in 2007

• Xcel Energy, High Bridge – Units 3,4,5,6 – Switch from coal to natural gas by 2008

• Xcel Energy, Riverside – Units 6,7,8 – Switch from coal to natural gas by 2009

• Xcel Energy, Sherburne County – Units 1,2,3 – NOX and SO2 reductions 

Minnesota and the other states participating in the Northern Class I consultation calls believe that in some 

areas their future EGU emissions were not correctly represented by IPM 3.0, because certain planned 

reductions were not included. Therefore, these states constructed an IPM 3.0 “will do” scenario, 

representing EGU emissions with known projects included. In general, known projects are those that 

have already gone through some kind of regulatory process, such as a permit application or notice to a 

state utility commission. However, the projects in the IPM “will do” scenario were not known in time to 

be submitted to EPA in order to be included in the base IPM3.0 projection. 

In addition, a few mistakes were noticed in the IPM3.0 predictions; examples of such errors affecting 

Minnesota facilities include the size of an EGU boiler being understated by 100MW and NOX emission 

rates being considerably lower than permit limits. Minnesota included these corrections in the “will do” 

scenario, resulting in a slight increase in predicted NOX emissions. Other states also included higher 

emissions where they felt IPM had inaccurately predicted the 2018 scenario, such as where facilities were 

shown with controls although utilities had indicated to the state that they would not be installing controls. 

Overall, these corrections resulted in higher regional emissions. 

Table 8.5 shows the base and adjusted emissions, and Chapter 8 also discusses the adjustments made by 

the states participating in the Northern Class I consultation process. In some cases, states also provided a 

“may do” scenario, which includes EGU reductions that are possible but have not yet gone through 

enough procedures within the state to be sure that they will be undertaken. However, Minnesota did not 

rely on the “may do” scenario in any modeling or determination of the RPG. Therefore, the emissions 

from the “may do” scenario are not shown here, though they can be seen for the contributing states on 

page 12 of the consultation letter that is Appendix 3.2. 

Best Available Retrofit Technology (BART)

As documented in Chapter 9, Minnesota has several emission sources that are subject to BART. 

Minnesota has incorporated language into its rules making any standard or other requirement established 

under section 169A (Visibility Protection for Federal Class I areas) or 169B, including emission limits 

established in the determination of best available retrofit technology, “an applicable requirement for 

stationary sources.” (See Appendix 9.7) 

As mentioned previously, MPCA has made BART determinations for Minnesota’s subject to BART 

EGUs. However, as described in Chapter 9, determining BART for the pellet furnaces at Minnesota’s 

taconite facilities is difficult. MPCA has made BART determinations, but is unable at this time to set a 

corresponding BART emission limit for most of the pellet furnaces. Therefore, at this time, we cannot 

predict the full extent of the emission reductions that will result from BART in Minnesota. 

The MPCA is requiring the taconite facilities to continuously monitor or use a comparable alternative 

method to obtain more accurate estimations of their emissions, and report their emission data to MPCA. 

It has been shown in the past that installation of continuous monitors allows facilities to more efficiently 

monitor and manage their combustion processes, resulting in less fuel usage and fewer emissions. The 
94 

MPCA expects this could result in emission reductions of 5 –30%, depending on the facility, simply due 

to combustion management. 

After a year of emission data is obtained, MPCA will review the data and set necessary BART emission 

limits; these emission limits will be incorporated into facility Title V permits. In the Five Year SIP 

review, the MPCA will document those emission limits and the level of reductions they represent from 

the 2002 base year emission inventory. For more information on BART, see Chapter 9. 

The states surrounding Minnesota and the contributing states have made varying decisions about BART, 

resulting in a wide range of potential emission reductions due to BART. Chapter 8 and the TSD describe 

the emission reductions from BART in other states that were incorporated into Minnesota’s modeling.

Other Federal Programs

Minnesota also anticipates some significant emission reductions resulting from several federal rules that 

will be implemented in the next several years. These reductions were included in the modeling of 

predicted 2018 emissions. 

• Tier II for on-highway mobile sources 

• Heavy-duty diesel (2007) engine standards 

• Low sulfur fuel standards 

• Federal control programs for nonroad mobile sources 

PM2.5 and Ozone SIPs

Minnesota is currently in attainment with the NAAQS for PM2.5 and ozone, and therefore was not 

required to submit SIPs showing decreases in these pollutants. However, several of the states that impact 

BWCAW and VNP are or will be submitting SIPs that include plans to reduce these pollutants and their 

precursors. These reductions will also reduce precursors to regional haze. Emission reductions included 

in SIPs from contributing states were not available in time to be included in this SIP. Minnesota has 

asked contributing states to provide information on emission reductions as they complete their SIPs, so 

that Minnesota may include this information in future modeling and the Five Year SIP Assessment. 

Additional Emission limitations and schedules of compliance 

40 CFR 51.308(d)(3)(v)(C) requires Minnesota to identify additional measures to meet visibility goals 

when ongoing programs alone are not sufficient. It appears that ongoing air pollution control programs 

are not sufficient to meet the URP at Minnesota’s Class I areas, or at Isle Royale, to which Minnesota is a 

significant contributor, through 2018. Even if they were sufficient to meet the URP, the state is required 

to investigate other reasonable control strategies. 

Certain voluntary emission reductions, not mentioned previously, appear likely to occur among 

Minnesota’s taconite industry. Based on this information, and knowledge of reductions occurring at 

EGUs, Minnesota adopted the following strategy as a “backstop,” ensuring that these planned reductions 

take place and providing incentives for other emission reductions. The strategy also ensures that 

Minnesota’s sources obtain their fair share of emission reductions and addresses concerns about industrial 

expansion near the BWCAW and VNP. 

Plan for Emission Reductions in Northeast Minnesota

Minnesota’s Class I areas are located in the Northeastern region of the state. This area, sometimes known 

as the Arrowhead or Iron Range, contains some major industrial sources that are high emitters of the two 

main haze causing emissions – SO2 and NOX. These high emitters (as of 2002) include EGUs and the 
95 

taconite industry, a unique iron ore mining and processing industry with only eight operating facilities in 

the nation, six of which are located in Northeast Minnesota. 

In addition, several new sources are likely to open on the Iron Range in the next few years, adding to the 

emissions in the region. The combination of geographic proximity, high existing emissions, and potential 

new sources has led to a high level of concern over the impact of this area on visibility. Therefore, in 

cooperation with the Federal Land Managers, Minnesota has developed a plan that sets emission 

reduction targets in the six counties closest to VNP and the BWCAW. The concept plan for Northeastern 

Minnesota, developed by MPCA and the FLMs and with extensive stakeholder input, is attached as 

Appendix 10.4. This section of the SIP focuses on implementation of the plan. 

Large point sources located in St. Louis, Lake, Cook, Carlton, Itasca and Koochiching counties that 

emitted over 100 tons per year of either SO2 or NOX in 2002, or have the potential to emit over 100 tons 

per year of either pollutant (if not in existence in 2002), will be subject to a region-wide target for 

emission reductions compared to the 2002 emission inventory. 

The emission reduction target was derived from the URP line for Voyageurs National Park. Many RPOs 

and states have determined from technical analyses that much of their visibility impairment is caused by 

sources beyond the state’s control – sources like organic carbon from wildfires, windblown dust, or 

international transport of emissions. In order to try to determine reasonable progress without the impact 

of non-controllable sources, “species-specific” glide slopes are created. This involves changing the 

deciview glide path to a glide path for light extinction, and then separating out the different types of 

particles based on how they contribute to the overall light extinction. Although Minnesota did not use 

this approach in calculating the RPG, it was used in developing the emission reduction target. 

In order to focus solely on controllable impacts, the effects of emissions from outside Minnesota, 

emissions that are biogenic or otherwise difficult to control, and emissions that are at predicted natural 

conditions were removed. This resulted in 75% of all visibility impacts assumed to be uncontrollable by 

the MPCA. This left ammonium sulfate and ammonium nitrate from in-state sources; these particles are 

caused by SO2 and NOX, pollutants with established methods of control. Calculations were done to 

determine the percent decrease in light extinction due to these particles needed to achieve the 2018 

visibility goal, and the assumption made that the extinction coefficient changed in direct proportion to the 

change in emissions from the region. Since light extinction from these particles needs to decrease by 

about 28% to reach the glide path, the ultimate target was set as a 30% reduction in emissions.79 

In short, the emission reduction target is intended to reflect the level of reductions needed in ambient 

concentrations of sulfate and nitrate in order to meet the URP for those pollutants, adjusted for the level 

of emissions that are uncontrollable or outside the domain.80 

Based on this technical analysis, Minnesota is establishing an emission reduction target or goal of a 

reduction in combined SO2 and NOX emissions from the subject sources of 20% by 2012 and 30% by 

2018. 

 

79 The MPCA would like to thank Scott Copeland of the CIRA/VIEWS Staff for his invaluable assistance in the 

technical work, such as deriving the species-specific glide path, needed to set the emission reduction target. 

80 Note that changing the percentage of impacts found to be uncontrollable did not make a major difference in the 

percent reductions needed to meet the glide path. It should also be noted that the approach does not consider 

modeling of individual sources, but treats all emissions as though they have equal potential to cause impacts. It also 

does not explicitly account for differing mass extinction efficiencies of NO, NO2 and SO2.
96 

Although most of the largest sources in this region are subject to BART and many are undertaking 

voluntary emission reduction projects, this target aims for overall larger emission reductions than are 

otherwise likely. 

Table 10.4: NE Minnesota Emission Reduction Target 

Year Total Emitted (tpy) 

2002 – Combined SO2 and NOX emissions 95,562 

2012 Goal – 20% Reduction 76,450 

2018 Goal – 30% Reduction 66,894 

This area was targeted for controls under the long-term strategy for several reasons. First, the MPCA’s 

analysis of 2002 emissions from the top 18 emitting point sources within Minnesota show that sources 

from this region make up just 1/3 of the total emissions but provide 2/3 of the total visibility impact. (See 

Chapter 8, on modeling.) Therefore, they have a much larger impact on the Class I areas than emissions 

from farther away. In addition, the taconite facilities may be currently uncontrolled or under-controlled 

for SO2 or NOX, and on the books control strategies are projected to cause fewer emission decreases in 

this region than in the remainder of the state. 

The MPCA will track annual SO2 and NOX emissions from all covered sources in the region, both actual 

emissions (as submitted to the emission inventory) from existing sources and potential emissions from 

new or modifying sources that have submitted complete permit applications. 

Minor sources (<100 tpy) are not included in the Northeast Minnesota plan, and their emissions will not 

be tracked annually. However, in 2012 and 2018, the MPCA will evaluate the emissions from minor 

sources that hold individual or registration permits in order to determine how those emissions have 

changed from the 2002 baseline. 

This tracking process will allow the MPCA to take a holistic look at the emission changes in the region, 

rather than simply addressing the largest sources that individually contribute to visibility impairment. 

The existing individual sources whose emissions will be tracked are: 

• Minnesota Power Inc - Boswell 

• US Steel Corp - Minntac 

• Hibbing Taconite Co 

• US Steel - Keewatin Taconite 

• Northshore Mining Co - Silver Bay 

• Minnesota Power - Taconite Harbor 

• United Taconite LLC - Fairlane Plant 

• Minnesota Power Inc - Laskin 

• Arcelor Mittal Mining Co 

• Sappi Cloquet LLC 

• Boise White Paper LLC - Intl Falls 

• Virginia Dept of Public Utilities 

• Duluth Steam Cooperative Assoc. 

• Minnesota Power Inc - ML Hibbard 

• Hibbing Public Utilities 

• Blandin Paper/Rapids Energy Center 

• Georgia-Pacific - Duluth Hardboard 

• Ainsworth Engineered LLC-Cook 

• Ainsworth Engineered LLC - GR 
97 

The MPCA will make publicly available, most likely electronically, an annual update of actual and 

forecasted emissions from the tracked sources in the region, along with the most recent monitored 

visibility conditions available.81 In addition, the MPCA will do a calculation of emissions in the region 

and progress towards the reduction target when any new major source applies for a permit to locate in this 

six-county region, or an existing source requests a major modification that would require a PSD permit. 

This information will be shared with the FLMs for their review prior to permit issuance, and will be 

available as part of the public notice process prior to permit issuance. 

MPCA is requiring CEMs or a comparable emission estimation method to be applied by the taconite 

facilities as part of BART. This will allow facilities to closely monitor future emissions. It may also 

provide information about the accuracy of the 2002 baseline emission levels; there is the potential for 

adjusting the baseline level from which emissions must be reduced in light of additional information. 

However, changes in fuel types and physical modifications to the taconite furnaces undertaken since 2002 

make accurate emission comparisons challenging. These changes are expected to result in decreased SO2

and NOX emissions from the taconite industry as a whole. Because emissions from taconite facilities are 

believed to have made up 47% of the 2002 emissions from stationary sources in the six-county area, the 

MPCA will attempt to take the uncertainty about the 2002 emissions into account when determining if 

additional emission reductions to meet the target are needed. 

Based on the BART analyses, MPCA has determined that the six taconite facilities may be 

undercontrolled, and that very few emission control technologies are known to be effective for the 

industrial processes involved in taconite production. Minnesota will therefore require these facilities to 

investigate control technologies and pollution prevention practices for their indurating furnaces through 

pilot tests or other mechanisms conducted on-site at the facilities, and report to MPCA on the feasibility 

and cost effectiveness of said technologies and practices. 

These reports will likely be structured very much like the facilities’ BART analyses, evaluating the 

feasibility of implementing piloted technology at a large scale, the costs of installing controls, and other 

impacts. The MPCA will conduct a review of the taconite facilities’ reports on the piloted control 

strategies and pollution prevention options investigated by the taconite facilities. We anticipate that the 

facility reports and MPCA’s subsequent analysis will be made available for public review, through a 

similar process as used for the BART analyses. 

The MPCA will evaluate the piloted potential control strategies using the statutory factors (cost of 

compliance, time necessary for compliance, energy and non-air environmental impacts, the source’s 

remaining useful life, and visibility impact) and considering the progress towards the overall emission 

target. That progress will become a sixth factor considered in determining what control strategies or level 

of emission reductions are reasonable. Also, the degree to which 2002 emissions were over or underestimated will be considered, at least qualitatively. 

The MPCA believes that the pilot tests at existing facilities and installation of emission control equipment 

at new taconite facilities will demonstrate that feasible, reasonable controls exist for the taconite facilities. 

Regardless of the status of the overall Northeast Minnesota emission target, such reasonable emission 

reduction measures will be required to be implemented as part of the state’s long-term strategy. The 

status of the emission target will be used primarily to inform the consideration of cost-effectiveness – if 

the overall regional emission reduction target is being met, the maximum $/ton cost-effectiveness level 

considered to be reasonable would likely be lower. Should more reductions be needed to meet the 

emission target, then a higher $/ton figure may be considered reasonable. 

 

81 The first annual tracking spreadsheet was posted in January 2009 and is available at: 

http://www.pca.state.mn.us/publications/aq-sip2-11.pdf 
98 

If it appears that other facilities will need to implement control strategies in order for the emission 

reduction target to be met, even after all voluntary EGU reductions have occurred and the determination 

of additional reasonable controls on the taconite facilities has been made, the MPCA will do a preliminary 

cost analysis of feasible pollution prevention and control options to evaluate whether further analysis by 

the facilities is warranted. If needed, such analysis will be requested by the MPCA. This further analysis 

would be used to determine reasonable control strategies that should be implemented by those sources. 

Reasonableness will be evaluated based on the same factors listed above. 

Although the regulatory or enforceable mechanism that will be used to require these reasonable emission 

reductions is not yet known, the MPCA anticipates that the determination of reasonable controls will be 

included in the Five Year SIP Assessment. Minnesota would likely implement the requirement for 

additional emission reduction measures, for both the taconite facilities and any other facilities where 

additional controls are found to be reasonable, through a “reasonable progress” requirement that would 

ultimately apply an emission limit to each facility where additional controls have been found to be 

reasonable. This limit could be set through a state rule or through amendments to each facility’s Title V 

air emission permit. 

In cooperation with the FLMs, the MPCA has developed a strategy for reporting progress towards the 

emission reduction goals and for consulting with the FLMs to determine necessary additional actions. 

The reporting is designed to mesh with the requirements of the Five Year SIP assessment. In that 

assessment, the MPCA will compare actual emissions to the emission target and determine 1) if the 2012 

target has been met and 2) if the 2018 target is likely to be met. Throughout the implementation period 

for this SIP, if it is projected that either target will not be met, the MPCA will consult with the FLMs, 

tribes and other stakeholders to determine what actions are needed to meet the 2018 target, taking into 

account the factors such as the difference between actual emissions and the target, plans for emission 

reductions between 2013 and 2018, the trends in nitrate and sulfate concentration and visibility in 

BWCAW and VNP, modeled visibility for 2018, and the availability of cost-effective emission reduction 

strategies. Actions could range from simply continued tracking to further assessment and potential 

implementation of additional emission reduction measures by facilities. 

The following table lays out the relevant timelines for the interlinked components of BART and the LTS 

in Northeast Minnesota. 

Table 10.5: BART and Northeast Minnesota Plan Timeline 

Process Dates

Begin data collection and reporting for taconite facilities with new 

CEMs/PEMS, as required by Administrative Orders 

November 2008 

Begin annual tracking of NE Minnesota Plan emissions December 2008 

MPCA determines remaining BART limits for each taconite facility By August 31, 2011 

MPCA determines if 2012 target will be met, and projects status of 

2018 emission reduction target. 

January – December 2012 

Taconite facilities conduct pilot testing of potential control strategies 

and pollution prevention 

July 2011 – December 2012 

Taconite facilities report to MPCA on results of pilot testing By March 1, 2013 

MPCA reviews pilot testing reports and determines if any additional 

controls are reasonable 

March – June 2013 

MPCA does preliminary analysis of potentially reasonable reductions 

from non-taconite facilities in NE Minnesota. 

January – June 2013 

MPCA develops enforceable mechanism to require any additional 

control found to be feasible, for both taconite and (if necessary) nonJuly 2013 – June 2014 
99 

taconite facilities 

MPCA submits 5 year assessment which includes BART limits, 

determination of additional reasonable controls. 

July 2014 

Facilities install any additional controls found to be reasonable 2015 and forward 

It should be noted that the economic downturn has impacted operations at the taconite facilities. Although 

some data collection began in November 2008, the majority of the facilities have subsequently idled their 

operations. The deadlines in Table 10.5 have been revised from the initial draft SIP to recognize that data 

collection is not likely to begin until lines resume operation, likely in fall of 2009 or early 2010, thereby 

impacting when the MPCA will be able to set BART limits and when facilities will be able to begin 

investigating potential controls. 

Emissions from the six-county region covered by the Northeast Minnesota plan will continue to be held to 

a level 30% below 2002 levels beyond 2018. In future SIP revisions, the MPCA will consult with the 

FLMs and evaluate the necessity of maintaining emissions from Northeast Minnesota at this level and the 

possibility of continuing reductions from the area in order to reach the long-term visibility goals. 

Measures to mitigate the impacts of construction activities 

40 CFR 51.308(d)(3)(v)(B) requires Minnesota to consider measures to mitigate the impacts of 

construction activities. Some of the main impacts of construction activities include the impacts of 

emissions from nonroad mobile and diesel engines and fugitive emissions resulting from land clearing 

and construction. Emissions from nonroad mobile sources and diesel engines will be decreased between 

now and 2018 due to federal on the books control strategies. 

The impact of construction activities will continue to be mitigated through the federal general and 

transportation conformity rules, which are included into Minnesota’s SIP. In addition, Minnesota has a 

state rule, Minnesota Rule 7011.0150, which requires all reasonable measures to be undertaken to prevent 

particulate matter from becoming airborne. This rule is already included in Minnesota’s SIP. 

7011.0150 PREVENTING PARTICULATE MATTER FROM BECOMING AIRBORNE. 

No person shall cause or permit the handling, use, transporting, or storage 

of any material in a manner which may allow avoidable amounts of 

particulate matter to become airborne. 

No person shall cause or permit a building or its appurtenances or a road, 

or a driveway, or an open area to be constructed, used, repaired, or 

demolished without applying all such reasonable measures as may be required 

to prevent particulate matter from becoming airborne. All persons shall 

take reasonable precautions to prevent the discharge of visible fugitive 

dust emissions beyond the lot line of the property on which the emissions 

originate. The commissioner may require such reasonable measures as may be 

necessary to prevent particulate matter from becoming airborne including, 

but not limited to, paving or frequent clearing of roads, driveways, and 

parking lots; application of dust-free surfaces; application of water; and 

the planting and maintenance of vegetative ground cover. 
100 

Measures to mitigate the impacts of new sources 

In terms of the construction of new major sources, the visibility impacts of such sources will continue to 

be managed in conformance with existing requirements pertaining to New Source Review and Prevention 

of Significant Deterioration, for which Minnesota operates a delegated PSD program. The PSD program 

requires the installation of BACT and modeling of the project’s impacts on local air quality. New sources 

or major modifications outside the Northeast Minnesota Plan also need to screen their emissions. If they 

are judged to have a potential adverse impact on visibility, those projects will need to perform more 

sophisticated modeling and analysis of their proposed impacts on Class I areas, including their effects on 

visibility.82

Sources covered by the Northeast Minnesota Plan that propose PSD modifications for haze pollutants will 

have to install BACT and ensure that their emissions fit into the budget for the Plan. The PSD regulations 

also require the consideration of other impacts to the environment. The proximity of new and modified 

facilities to Minnesota’s Class I areas, even those covered by the Plan, necessitates consideration of 

visibility in this step. (Historically, the MPCA has incorporated similar environmental factors into the 

BACT determination by adjusting the cost-effectiveness threshold.) This can lead to the application of 

more effective control strategies and thus lower emission rates. In addition, the MPCA could cite the 

visibility section of the PSD rule in order to ask for controls. Through the PSD process, which includes 

review by and input from the Federal Land Managers, particularly on appropriate BACT determinations 

and determinations of adverse visibility impact, the MPCA will be able to minimize the impact of new 

sources on visibility. 

The Northeast Minnesota plan attempts to move from the incremental approach of the traditional PSD 

visibility program towards a more holistic approach. If emissions are declining under the Northeast 

Minnesota Plan, visibility should be improving; this is a better approach than determining if simply the 

addition of pollutants will not have too great an impact on the Class I area. 

For sources subject to the Northeast Minnesota plan described previously, the intent is for the MPCA to 

sign a Memorandum of Agreement with the FLMs that would not require new or modifying facilities in 

that Northeast Region to conduct a detailed visibility analysis under PSD, as long as the region as a whole 

is meeting the stated emission reduction goals. Should the Northeast region fail to meet the reduction 

goals, full visibility analysis would be required under the PSD program. Until the memorandum is signed, 

the MPCA will continue to require new or modifying facilities to undertake a visibility analysis as 

needed. 

Source retirement and replacement schedules 

Source retirement and replacement schedules, which must be considered under 40 CFR 51.308 

(d)(3)(v)(D) in developing reasonable progress goals, will be managed in conformance with existing 

requirements under the PSD program, much as described above. 

Agricultural and forestry smoke management 

Under the requirements of 40 CFR 51.308(d)(3)(v)(E) Minnesota must consider smoke management 

techniques for the purposes of agricultural and forestry management in developing the long-term strategy 

to achieve the reasonable progress goal. 

Impact of Fires on Visibility

Vegetative burning produces NOX, organic compounds, carbon monoxide, carbon dioxide, and particulate 

matter. Approximately 90% of smoke particles from wildland and prescribed fires are PM10, while about 

 

82 This determination is generally made by the Federal Land Managers. 
101 

70% are PM2.5.

83 Of the pollutants that derive from vegetative burning, those that mainly impact visibility 

are nitrates, ozone, organic carbon (OC), and elemental carbon (EC). Ozone, while not directly produced 

by fires, may form downwind of fires due to photochemical reactions of combustion products (NOX and 

VOCs). Ozone can also participate in nitrate and sulfate particle formation. 

Of the main visibility impairing pollutants, OC and EC are formed from fire; however, neither are unique 

products of fire. EC, for example, is a primary product of the combustion of any carbon fuels, and 

therefore can come from diesel emissions as well as vegetative burning. Organic aerosols can be the 

outcome of either primary emissions or secondary formation from gas phase emissions. OC can be 

attributed to human sources of VOCs or to biogenic emissions from both conifer and broad-leaved trees in 

the summer growing season. 

At both VNP and BWCAW, OC is the largest component of PM2.5 mass measured in summer by the 

IMPROVE monitors. When light extinction is calculated from the filter measurements, OC is 

proportionally less significant but still an important pollutant – roughly equal to sulfate in its effect on 

summertime visibility (Figure 10.3, Appendix 3.1.) 

Both OC and EC are products of fire and monitoring data on days affected by fire will show increases in 

these pollutants. In general, biogenic emissions of OC are not easily distinguished from emissions from 

fire,84 but several studies have been done to determine the causes of high OC in the Class I areas. It 

appears that most OC seen in the Northern Class I areas is biogenic, coming from plants as opposed to 

fire. 

Sheesley and Schauer conducted a study at Seney Wilderness that examined the sources of organic carbon 

affecting the area.85 Using a marker species associated with vegetative burning, they found the highest 

levels of this marker in the winter months, likely indicating burning due to use of wood stoves and 

fireplaces. There was a lesser peak from June through September; the summertime levels of the marker 

species indicate high secondary organic aerosols, not primary emissions of wood smoke or other sources. 

These findings were reviewed in a 2005 MRPO issue paper, which concluded “the contribution of fires to 

annual average PM2.5 concentrations and visibility impairment in the Upper Midwest is relatively small. 

Nevertheless, fires may cause problems on an episodic basis.”86 

To further investigate the impact of fire, a MRPO contractor developed an inventory of fire emissions 

from agricultural, prescribed, and wildfire burning in 2001 – 2003 for the Midwest states; the report 

shows that Minnesota has the greatest emissions of the eight states due to burning.87 In addition, total 

acres burned by both wildfire and prescribed fire increased in each successive year, and total acres burned 

in Minnesota were usually more than twice the next highest state.88

Because of the relatively high levels of burning and the fact that prescribed burning is likely to continue 

to increase, it is important to assess the effects of fires in Minnesota on the visibility data, especially for 

the 20% worst days. 

The following table identifies days among the worst 20% visibility days of the baseline period that have 

the highest levels of organic and elemental carbon. 

 

83 EPA, 1998 84 Debell, et al., 2006. 

85 Sheesley & Schauer, 2004. 

86 MRPO, 2005a, p 9. 

87 Boyer, et al, 2004. Table 8-2, p 67. 

88 Boyer, et al, 2004. Table 8-3, p 70. 
102 

Table 10.6: W20% Days with Highest OC and EC Light Extinction 

(Baseline Years)* 

Class I 

area 

Species 2000 2001 2002 2003 2004

Sept 30 

NA 

June 1 June 28 July 19 June 5 Aug 7 Aug 25 July 17 July 26 

BWCAW OC 26.64 NA 66.50 125.56 27.87 28.52** 55.67 71.68 34.36 

EC 9.24 5.74 7.13 3.58 2.02 4.68 3.40 3.50 

VNP OC 30.58 89.38 71.23 169.82 25.56 32.05 57.51 80.58 44.83 

EC 10.68 8.29 5.93 8.58 4.86 3.44 6.71 4.53 4.05 

* Threshold value= light extinction (Bext) for OC + EC > 50% of total daily Bext AND total Bext > 50 Mm-1

** For this date, total Bext was < 50 Mm-1, but the day was investigated due to high OC + EC impact. 

MRPO examined five of the days shown above to assess whether OC from fire may cause or contribute to 

these elevated values.89 Using back trajectories and satellite maps of fires, it appears that monitoring data 

for four of the five days was highly influenced by wildfires in Manitoba and Saskatchewan. 

The MPCA analyzed those days not analyzed by MRPO. Overall, most of the nine days shown above 

with the highest light extinction due to OC and EC appear to be influenced by fires in Canada. There are 

only two days, June 5, 2003 and July 26, 2004, where it is reasonable to conclude that fires within 

Minnesota contributed to the elevated concentrations of OC and EC. On these days, a small prescribed 

burn and a wildfire upwind of the monitor, respectively, appear to affect the IMPROVE data. 

In Minnesota, federal and state land managers generally conduct prescribed burning during a spring 

season (March 15 - May 31) and a fall season (Sept 15 - Oct 31). None of the 20% worst days shown in 

Table 10.5 occur in these intervals. Elevated concentrations of OC in the summer can be due in part to 

wildfires, but can also be due to high biogenic emissions. Because of the extensive forests to the north of 

Minnesota, it is likely that some of the high OC measured in summer at the IMPROVE monitors is 

biogenic secondary organic aerosol that originates in Canada. Further details on the visibility impact of 

fires can be found in Appendix 10.7. 

MRPO determined that subtracting the five days of high OC concentration from the 20% worst days, in 

general, had a relatively small effect on visibility impairment for the baseline average – a range 0.3 dv at 

Minnesota’s Class I areas to less than 0.2 dv at Michigan’s Class I areas.90 

Although the data show that fires do have some impact on visibility in Minnesota’s Class I areas, the 

impacts on the 20% worst days tend to be only a few poor visibility days in the summer caused by 

wildfires. Often these wildfires occur in Canada. For this reason, Minnesota determined that OC 

particles are not good candidates for additional controls as part of the long-term strategy. Emissions from 

wildfires should be included in natural condition estimates, and any transboundary fire impacts must be 

addressed by EPA. Emissions from prescribed and managed fires within Minnesota are managed in 

conformance with Minnesota’s Smoke Management Plan, described below. 

Agricultural Smoke Management

Agricultural burning requires an open burning permit from the Minnesota Department of Natural 

Resources. In general, agricultural burning in Minnesota is limited to grass and stubble burning, 

particularly of bluegrass and timothy grass. This light fuel type produces short-term smoke events 

 

89 MRPO, 2007b; LADCO, 2008. 

90 MRPO, 2007b; LADCO, 2008, pg 45. 
103 

without a lot of combustion of biomass and smoldering. In addition, most agricultural burning occurs in 

the northwest area of the state, away from the Class I areas. 

 Agricultural burning is not covered by Minnesota’s Smoke Management Plan, and EPA’s Interim Air 

Quality Policy on Wildland and Prescribed Fires specifies that it does not apply to agricultural burning.91 

Minnesota is not addressing agricultural burning in this SIP, as an analysis of the days during the baseline 

visibility period with the highest concentrations of organic and elemental carbon shows that none of these 

days were attributed to agricultural burning within Minnesota. 

EPA is due to issue new final guidance for wildland and prescribed fire, and separate guidance is likely to 

be issued to address agricultural burning. Should agricultural fires become an important contributor to 

poor visibility, Minnesota will address agricultural fires in future SIP revisions. 

Forestry Smoke Management

Minnesota’s various ecosystems are dependent on and adapted to fire disturbance, and prescribed burning 

has become a common management tool for these ecosystems. Prescribed burning is also used to reduce 

the frequency, size, and intensity of wildfires and consequently reduce total emissions from vegetative 

burning. This benefit to air quality is promoted by the application of the Smoke Management Plan 

(SMP), whereby practices to reduce the impact of burning on air quality are added to the “prescription” 

that determines the conditions for igniting and managing the fire. 

Most open burning in Minnesota is required to have a burn permit, and a process is in place for 

authorizing those permits and granting approval to manage fires. The Commissioner of the Minnesota 

Department of Natural Resources (DNR) is granted authority in Minnesota Statutes 88.01 to 88.22 to 

control open burning; the DNR reviews burn applications and issues burn permits for all open burning in 

Minnesota, except on federal and tribal lands.92 

More importantly for management of fire emissions, Minnesota has a Smoke Management Plan that has 

been in effect since 2002; although briefly described here the MPCA is not proposing that it be formally 

incorporated into Minnesota’s SIP. The SMP is subject to occasional updating and revision, and was 

updated in December 2007. 

The MPCA works with state and federal land managers as part of the Minnesota Incident Command 

System (MNICS) Prescribed Fire Working Team93 to develop the SMP. The SMP is implemented 

through a Memorandum of Agreement between the U.S. Department of Agriculture, Forest Service; U.S. 

Department of the Interior, National Park Service; U.S. Department of the Interior, Fish and Wildlife 

Service; The Nature Conservancy; Minnesota Department of Natural Resources; and the MPCA. The 

signatory agencies agree to apply the provisions of the SMP to all prescribed fires that they ignite and all 

naturally occurring fires that they manage. 

Minnesota believes this program addresses visibility impairment due to fires. Minnesota certified in a 

letter to the EPA on September 2, 2004 that a basic program has been adopted and implemented. EPA’s 

reply is included in Appendix 10.8. The key provisions of the 2002 SMP are described below, and a 

complete copy of the SMP can be found on the web. 

According to EPA’s guidance, “The purposes of SMPs are to mitigate the nuisance and public safety 

hazards...posed by smoke intrusions into populated areas, to prevent deterioration of air quality and 

 

91 U.S. EPA, 1998. 

92 For more information, see Minnesota DNR, Burning Questions (webpage). 93 Now Prescribed Fire/Fuels Working Team 
104 

NAAQS violations, and to address visibility impacts in mandatory Class I Federal areas.”94 Similarly, 

Minnesota’s SMP sets out “regional haze rules to improve visibility in the mandatory Class I areas” as a 

primary reason for implementing a smoke management plan in the state. Minnesota considers the SMP to 

be an important tool to achieve the purposes of the Regional Haze Rule. In addition to addressing 

NAAQS and regional haze issues, Minnesota’s SMP was developed due to predicted significant increases 

in the use of prescribed burning. 

Minnesota’s SMP is based on EPA’s Interim Air Quality Policy.95 It includes the following requirements 

as laid out in that guidance: 

• Authorization to burn 

• Minimizing air pollutant emissions 

• Smoke management components of burn plans 

• Actions to minimize emissions 

• Evaluation of smoke dispersion 

• Air quality monitoring 

• Public education and awareness 

• Surveillance and enforcement 

• Program evaluation 

Under the SMP, all prescribed fires must have burn plans that include the following elements: 

• Location and description of the area to be burned 

• Personnel responsible for managing the fire 

• Type of vegetation to be burned 

• Area (acres) to be burned 

• Amount of fuel to be consumed (tons/acre) 

• Fire prescription including smoke management components and dispersion index 

• Criteria the fire manager will use for making burn/no burn decisions 

• Safety and contingency plans 

The SMP requires calculation of a dispersion (or ventilation) index based on mixing height and transport 

winds to mitigate smoke impacts. Dispersion index category is used with fuel type and daily size of fire to 

determine minimum proximity to nearest downwind receptors. Prescribed burns cannot be ignited 

outside these conditions. 

Minnesota’s SMP gives the MPCA responsibility for an annual assessment of the effect of prescribed 

burning on air quality within Minnesota. This annual review includes an examination of both PM2.5 and 

ozone (O3) monitoring data in Minnesota, including data from the IMPROVE monitors, for correlations 

between air quality and wildland and prescribed fires. This report is provided to the Prescribed Fire/Fuels 

Working Team of MNICS as part of the annual evaluation of the SMP. 

The four step process generally used is as follows: 

1) Examine the air sample data from monitors at geographically appropriate sites for high values of 

PM2.5 and ozone during the prescribed fire season; 

 

94 U.S. EPA, 1998. 

95 U.S. EPA, 1998. 
105 

2) Determine the wind speed and direction during the day and the hours of elevated PM2.5 and ozone 

concentrations; 

3) Determine the time, location, and size of prescribed burns conducted by SMP-participating 

agencies with respect to the time and location of the recorded air concentrations (includes 

evaluation of wildfires); and 

4) Use back-trajectory mapping to determine the movement of higher-elevation air parcels with 

respect to the location of potential fire sources. 

The Working Team also looks at the acres of prescribed burns planned for the next five years, the need to 

expand the scope of the program to include authorization of other open burning, and the need for changes 

in the SMP. 

Future of SMP and Fires

The Prescribed Fire/Fuels Working Team of MNICS completed a review and revision of Minnesota’s 

SMP in December 2007. 

Following is a summary of the major changes made to the SMP: 

• Additional participating agencies (Minnesota Department of Military Affairs and Minnesota 

Department of Transportation) 

• Update of acres burned by prescribed fire 

• Update of PM10, PM2.5, and O3 NAAQS description 

• Revision of “climate of smoke dispersion in Minnesota” section 

• Addition of references to EPA’s Exceptional Events Rule (March 2007) and effects on prescribed 

burning (including record keeping in burn plans to demonstrate exceptional events) 

• Revision of table in 4.2.3 “Smoke Management & Dispersion” and combination of dispersion 

index categories, fuel type/burn acres, and distance to receptors charts 

• Addition of the EPA’s Air Quality Index (AQI) information to Appendix 

• Update of PM10, PM2.5, and O3 monitors and locations table and maps in Appendix 

As necessary, the SMP will continue to be updated periodically by the participating agencies. 

Enforceability of emission limitations and control measures 

40 CFR 51.308(d)(3)(v)(F) requires Minnesota to ensure that emission limitations and control measures 

used to meet RPG are enforceable. 

Appendix 9.7 contains the state rulemaking that made both BART and CAIR applicable requirements for 

stationary sources. The Administrative Orders requiring CEMs or a comparable method of emissions 

measurement from the taconite facilities are included in Appendix 9.7. Minnesota requests EPA approval 

of these measures. 

Minnesota will submit additional enforceable documents in the Five Year SIP Assessment. Once 

established, BART emission limits will be included in each taconite facility’s Title V permit and 

submitted to EPA. In addition, the MPCA will develop enforceable documents such as permits, 

Administrative Orders, or a state rule that will require the taconite facilities to conduct the research into 

additional emission reduction measures (if such is not already being undertaken voluntarily and reported 

to the MPCA) and implement control strategies found to be reasonable. 
106 

Anticipated net effect on visibility resulting from projected changes to emissions 

40 CFR 51.308(d)(3)(v)(G) requires Minnesota to address the net effect on visibility resulting from 

changes projected in point, area and mobile source emissions by 2018. 

The emission inventory for Minnesota projects changes to point, area and mobile source inventories by 

the end of the first implementation period resulting from population growth; industrial, energy and natural 

resources development; land management; and air pollution control. These changes, and their net effect 

on visibility, are described in Chapter 8. 

Potential Future Projects and Impacts 

Other actions are likely to take place over the next 10 years that will impact visibility in the Class I areas 

in 2018, but which are not included in the RPG. 

For example, Minnesota expects several surrounding states to submit additional control measures in order 

to meet their responsibilities under the Regional Haze Rule and for attainment of the PM2.5 and ozone 

NAAQS. As these control measures are not yet proposed or implemented, they were not included in the 

RPG. The MPCA also intends to further investigate control measures that were shown by the EC/R 

report to be potentially reasonable under the four factors. This is discussed further below. 

In addition, there are the potential impacts of both climate change and regulations to reduce greenhouse 

gases. Climate change may well impact the meteorology of the area, affecting the transport of precursor 

pollutants. However, these impacts are extremely difficult to predict and are more likely to be seen over 

the long-term of the Regional Haze program (to 2064) rather than over the next ten years. In addition, 

research suggests that the “sensitivities of ozone and PM2.5 formation to precursor emissions are found to 

change only slightly in response to climate change.”96 This indicates that control strategies put in place to 

reduce precursor emissions (NOX and SO2), such as those in this SIP, will continue to be effective in 

reducing PM2.5, and haze, even if the climate has changed. 

Minnesota has implemented some rules and laws in order to reduce greenhouse gas emissions, and more 

such policies are likely to be forthcoming. For example, there is now a new Renewable Energy Standard, 

Minnesota Statute 216B.1691, requiring 25% of the state’s energy to come from renewable sources by 

2025. This is likely to lead to more non-fossil fuel based energy generation, perhaps leading to lower 

future emissions from electricity generation than currently predicted. (See Appendix 10.2). 

In addition, Minnesota has been engaged in a statewide process of determining what actions the state 

should take in response to global climate change. Although any measures undertaken as a result of this 

process will be intended to reduce emissions of carbon dioxide and other greenhouse gases, it is likely 

that some of them may have the added benefit of reducing emissions of fine particulate matter and its 

precursors, thereby helping to reduce regional haze. 

 

96 Liao, et al., 2007. p 8355. 
107 

Reasonable Progress Goals 

At this time, based on the aforementioned information, Minnesota is setting the reasonable progress goals 

at the deciview levels shown in the following table. 

Table 10.7: Reasonable Progress Goals for Class I areas 

Class I area 2018 Visibility 

20% Worst Days 

(dv) 

2018 Visibility 

20% Best Days 

(dv) 

Projected Annual 

Improvement 

2004-2018 

(W20%, dv) 

Projected 

Improvement by 

2064 

(W20%, dv) 

Year Reaching 

Natural 

Conditions 

(W20%) 

BWCAW 18.6 6.4 0.09 5.6 2093 

VNP 18.9 7.1 0.04 2.6 2177 

The RPG provides for less annual progress towards the ultimate visibility goals than the URP. 

The RPG set in this SIP is the minimum visibility improvement Minnesota considers to be reasonable, 

and contains emission reductions resulting from all controls currently known to be reasonable – namely 

BART, CAIR, other on the books and national strategies, and emission reductions due to the Northeast 

Minnesota Plan, all of which are described above in the long-term strategy. The MPCA anticipates that 

the levels indicated in this table represent an interim decision on the reasonable level of visibility 

improvement. 

Factors Impacting RPG 

International Emissions

There is some indication, particularly from the modeling performed by CENRAP, that Minnesota’s two 

Class I areas may have significant visibility impacts resulting from Canadian emissions.97 However, 

estimates of this international impact vary due to difficulties quantifying Canadian emissions and 

discrepancies between models. (For more information, see Chapter 8 and the TSD.) The MPCA requests 

that EPA work with Canada in order that future SIP revisions for regional haze will be able to include 

more accurate emission estimates and modeling in order to better quantify any international impact on 

visibility. Where necessary, EPA should then work with Canada and support reductions in haze-causing 

emissions. 

Emissions from Contributing States

At this time, Minnesota believes that the RPG in Table 10.6 is an appropriate goal because of uncertainty 

surrounding future levels of emission reductions. Some impacting states are working on a multi-SIP 

approach and have yet to determine what reductions are reasonable in their states for both haze and 

NAAQS attainment purposes. Although we cannot compel other states to undertake reductions, 

Minnesota believes that some additional emission reductions from other states have been shown to likely 

be reasonable, and that further emissions reductions will occur due to attainment SIPs, resulting in larger 

visibility improvement. 

Minnesota has used the EC/R five factor analysis report (see Appendix 10.5) the control cost analysis 

carried out by Alpine Geophysics for CENRAP and the CENRAP Control Sensitivity Model run 

(Appendix 10.6) to identify potentially reasonable region-wide emission reduction strategies that could be 

adopted in future years to strengthen Regional Haze SIPs. Minnesota has therefore asked the contributing 

states to evaluate whether these control strategies are reasonable, under the four factors, and to report the 

results of this analysis in their SIPs or Five-Year Assessments. (See Appendix 3.2) 

 

97 ENVIRON/UCR, 2007. pp 1-23 to 1-24 and p 5-2. 
108 

Preliminary indications from the contributing states are that those states are, at this time, unlikely to 

undertake additional emission reductions for regional haze purposes. Of the contributing states, Missouri 

has indicated in its SIP that it does not believe that it is a significant contributor to visibility in either of 

Minnesota’s Class I areas. Iowa has indicated that it does not feel that additional controls are costeffective due to their cost in $/deciview, and that further review of some controls is unwarranted due to 

the uncertain status of federal regulation. (See Appendix 3.2.) Although Minnesota has continued to 

consult with these states, we have been unable to resolve these disagreements. Therefore, Minnesota asks 

EPA to make a determination as to whether controls from these states to address visibility impairment in 

Minnesota’s Class I areas are appropriate. 

It should be noted that although modeling was done to evaluate the visibility conditions if the contributing 

states commit to certain control strategies that Minnesota has deemed to be potentially reasonable, 

Minnesota is not yet asking the contributing states to make such commitments. Instead, Minnesota has 

simply asked the contributing states to look at the reasonableness of those control strategies that could 

improve visibility in Minnesota’s Class I areas. 

In addition, the MPCA intends to continue to research control strategies and other means to strengthen the 

Regional Haze SIP. Should such strengthening measures be found, or should other states commit to 

control measures, Minnesota intends to revise the RPG for 2018 in the Five Year SIP Assessment, in 

order to reflect the additional control strategies found to be reasonable. 

Specific Control Strategies to Be Reviewed 

The specific strategies that at this time appear potentially reasonable, despite a lack of information to fully 

evaluate them at this time, and Minnesota’s expectation for each of these strategies for both Minnesota 

and the contributing states, are outlined below. 

EGU SO2 Reductions 

Minnesota has asked the contributing states to continue to look at their EGU emissions of SO2, with a 

particular focus on possible reductions in states with emission rates that appear to be higher than average 

among the Midwestern states. Although the MPCA recognizes that contributing states face a variety of 

regulatory demands and fuel types, making it perhaps difficult to attain uniform emission performance, it 

appears that an emission rate of about 0.25 lb/MMBtu should be achievable in a cost-effective manner. 

This is the level being achieved in Minnesota and Illinois, and the EC/R report shows that the “EGU1” 

scenario, a 0.15 lb/MMBtu emission rate, is generally achievable in the Midwest at a reasonable $/ton 

figure, estimated to range from $560 - $2,900/ton.98 

Minnesota would expect the identified states to demonstrate that reductions are occurring or being 

undertaken that will allow the state to reach the above-mentioned emission rates, or to evaluate strategies 

for reaching the emission rates and state in their SIPs or Five-Year SIP Assessments why further 

reductions of SO2 from EGUs are not reasonable. Further reductions may not be reasonable due to the 

cost of implementation or lack of impact on visibility impairment, but they should be evaluated for each 

state’s specific circumstances. 

At present, it appears as though Illinois has planned or proposed reductions that appear reasonable. It 

appears that more cost effective reductions are possible in Iowa, Missouri, North Dakota, and Wisconsin. 

Since Wisconsin is the largest non-Minnesota contributor to visibility impairment in Minnesota’s Class I 

areas, their efforts to reduce EGU SO2 emissions are particularly important. 

 

98 Battye, et al, 2007, pp 27 – 28. 
109 

EGU NOX Reductions 

In general, dispersion models have been less reliable in predicting the nitrate component of particulate 

matter (as compared to the sulfate component). Wisconsin, Missouri, and Illinois have already reduced 

NOX emissions to alleviate ozone standard violations, and Iowa appears to already have relatively low 

EGU NOX emissions. Minnesota has asked these states to share information on any NOX controls being 

undertaken as part of their ozone SIPs, in order for Minnesota to fully include any information on the 

resulting emission reductions. 

Minnesota has asked North Dakota to evaluate their EGU emissions of NOX and to describe in their SIP 

or Five-Year SIP Assessment why further reductions of NOX from EGUs are not reasonable. Again, an 

emission rate of approximately 0.25 lb/MMBtu appears to be a reasonable benchmark. Further reductions 

may not be reasonable due to the cost of implementation in $/ton or $/deciview or lack of impact on 

visibility impairment, but they should be evaluated for North Dakota’s specific circumstances. The EC/R 

report indicates that control strategies to reach a NOX level of 0.10 lb/MMBtu may be available in North 

Dakota in a range of $760 – $3,300/ton.99

Again, Minnesota acknowledges that each state is in a unique situation in terms of regulatory background 

and a general EGU fuel mix. The use of emission rates to identify areas where additional emission 

control strategies should be investigated does not mean that Minnesota expects all contributing states to 

achieve the same emission rates. 

However, Minnesota believes contributing states with higher emission rates need to evaluate potential 

control measures, and should, in their initial SIPs or Five Year SIP Assessments, show either enforceable 

plans to reduce emissions or a rationale for why such emission reductions are not reasonable. 

Should the five contributing states reach the 0.25 lbs/MMBtu EGU emission levels, and if: 

• States in the MRPO commit to the reductions asked of them by MANE-VU; and 

• Controls are installed at Xcel Energy, Sherburne plant;100 

then modeling shows the future visibility conditions are likely to be better than described in the RPG. 

These conditions are shown below, in Table 10.7. 

Table 10.8: Alternate Goals for Class I areas 

Class I area 2018 Visibility 

20% Worst Days 

(dv) 

2018 Visibility 

20% Best Days 

(dv) 

Projected Annual 

Improvement 2004-

2018 

(W20%, dv) 

Projected 

Improvement by 

2064 

(W20%, dv) 

Year Reaching 

Natural 

Conditions 

(W20%) 

BWCAW 18.3 6.4 0.11 6.9 2079 

VNP 18.7 7.1 0.06 3.4 2127 

Several other control strategies were shown to be potentially reasonable, though no modeling was 

performed on the resulting visibility improvement. 

ICI Boiler Emission Reductions 

Minnesota will commit to a more detailed review of potential NOX and SO2 reductions from large ICI 

boilers in order to determine if reasonable measures exist that could further strengthen this Regional Haze 

SIP. For ICI Boilers, the EC/R report indicated that cost-effectiveness ranges from $1,149 to $3,021/ton 

 

99 Battye, et al, 2007, pp 27 – 28. 

100 If emissions are controlled to the levels used in the modeling. See the TSD for more details. 
110 

of SO2 and $699 - $5,478/ton of NOX reductions in the Midwest.101 If significant cost effective 

reductions prove feasible from this sector, regulations or permit limits will be developed by 2013. 

Minnesota expects the five contributing states to also commit to this future evaluation. 

Other Point Source Emission Reductions 

Reciprocating engines and turbines appears to be a sector with potential cost effective NOX controls; the 

EC/R report estimates the cost of NOX controls to be between $240 - $8,200/ton.102 Minnesota commits to 

reviewing this sector in more detail and if, after consideration of planned federal control programs, cost 

effective reductions appear feasible, Minnesota commits to develop regulations or permit limits for major 

sources by 2012 in order to strengthen the SIP. Minnesota will expect the five other contributing states to 

make a similar commitment. 

Mobile Source Emission Reductions 

There appear to be relatively few additional cost effective NOX controls on mobile sources available to 

states, partially due to the large reductions resulting from federal requirements. Minnesota commits to 

work with MRPO states to implement appropriate cost effective NOX controls to improve visibility and 

lower ozone levels in non-attainment areas. 

NOx Modeling, Ammonia, Agricultural Sources 

It is not appropriate to commit to control of ammonia sources at this time. However, there is a clear need 

to improve 1) our understanding of the role of ammonia in haze formation, 2) our understanding of 

potential ammonia controls, and 3) the accuracy of particulate nitrate predictions. Minnesota does not 

believe that conducting such research solely on a state-based level would be appropriate at this time, as 

information on ammonia’s role particulate formation and potential controls is needed throughout the U.S., 

and regional similarities are likely. Minnesota therefore strongly encourages EPA and the regional 

planning organizations to continue work in these areas and commits to work with EPA and the RPOs to 

these ends. The MPCA hopes also to re-evaluate the growth factors used in predicting agricultural 

ammonia emissions and include that information in the Five Year SIP Assessment. 

To summarize, Table 10.8, below, contains all the relevant visibility conditions given throughout this SIP. 

Table 10.9: Visibility Conditions, URP and RPG for Minnesota’s Class I areas (dv) 

 Baseline 

W20% 

Baseline 

B20% 

2018 URP

W20% 

2018 RPG

W20% 

2018 Alt Goal 

W20% 

Natural 

W20% 

Natural 

B20% 

BWCAW 19.9 6.4 18.0 18.7 18.3 11.6 3.4 

VNP 19.5 7.1 17.8 19.0 18.7 12.1 4.3 

Steps in Reviewing Control Strategies and Revising RPG 

In reviewing additional control strategies to determine additional strengthening measures that are 

reasonable under the Regional Haze rule, the MPCA commits to further evaluation of reasonable control 

strategies that are possible within Minnesota. In addition, Minnesota will focus on strategies that will 

result in emission reductions in those other states that contribute more than 5% to visibility impairment in 

BWCAW and VNP: Wisconsin, Iowa, N. Dakota, Missouri and Illinois. The MPCA will work with these 

contributing states through their submittals of the first haze SIP and through 2013 to develop additional 

reasonable control strategies. 

 

101 Battye, et al, 2007, pp 45. 102 Battye, et al, 2007, pp 57. 
111 

In the Five Year SIP Assessment, the MPCA would submit enforceable documents for any additional 

control measures found to be reasonable within Minnesota. In addition, that report would contain a 

listing of the additional control measures to be implemented by the other contributing states. Minnesota 

would then submit modeling that includes all these enforceable measures and would revise the 2018 RPG 

if the modeling shows, as expected, a larger degree of visibility improvement resulting from the chosen 

control strategies. 

Timeline for Reviewing Control Strategies 

Minnesota commits to reviewing these control strategies on such a timeline that the Five Year SIP 

Assessment will include the four factor analysis for these additional control strategies and that any control 

strategies deemed to be reasonable by Minnesota or any contributing states will be in place to strengthen 

the SIP with an enforceable document (state rule, Order, or permit conditions). Although any control 

measures ultimately deemed to be reasonable may not be fully implemented by 2013, they will clearly be 

“on the way” and the SIP Report will include estimates of emission reductions and projected 2018 

visibility conditions. 

Acknowledging the different timelines among states, especially the fact that some states are far along in 

the process of writing their Regional Haze SIPs, Minnesota expects that all other contributing states 

would commit to a similar timeline of reviewing potential emission reductions for the Five Year SIP 

report, allowing for predictions of the emission reductions and visibility improvement resulting from the 

implementation of reasonable control measures by 2018 to be contained in that report. 

Minnesota has determined, based on the reasons delineated above, that the rate of visibility improvement 

by 2018 shown in Table 10.6 is reasonable and hereby adopts it as the reasonable progress goal (RPG) for 

the listed Class I areas. The RPG provides for an improvement in visibility for the most impaired days 

and ensures no degradation in visibility for the least impaired days. 
112 

Chapter 11. Periodic Plan Revisions and Determination of Adequacy 

2018 SIP Revision 

Each state is required by 40 CFR 51.308(f) to revise its regional haze implementation plan and submit a 

plan revision to EPA by July 31, 2018, and every 10 years thereafter. In accordance with the 

requirements listed in 40 CFR 51.308(f) of the federal rule for regional haze, Minnesota commits to 

revising and submitting this regional haze implementation plan by July 31, 2018, and every 10 years 

thereafter. 

Five Year Report 

In addition, 40 CFR 51.308(g) requires periodic reports evaluating progress towards the RPG established 

for each mandatory Class I area. In accordance with these requirements, Minnesota commits to 

submitting a report to EPA every five years following the initial submittal of the SIP, with the first report 

due December 15, 2014; this report will evaluate the progress made towards the RPG for each mandatory 

Class I area located within Minnesota and in each mandatory Class I area located outside Minnesota 

which may be affected by emissions from within Minnesota. The report will be in the form of a SIP 

revision, with the first report to be submitted within five years after submittal of this SIP revision. All 

requirements listed in 40 CFR 51.308(g) shall be addressed in the SIP revision for reasonable progress, 

including consultation with Federal Land Managers during the preparation of that SIP revision. 

Actions to be Taken Prior to Five Year Report 

In order to meet our commitments laid out in Chapter 10 of this SIP and to ensure the most accurate 

estimation of 2018 visibility is made in the Five Year Assessment, the actions laid out in the following 

table need to occur. The table begins with those activities where MPCA is the responsible party (and to 

which MPCA is committing in this SIP), and moves on to recommended actions for other parties, such as 

EPA and the RPOs. These actions are described in detail elsewhere in the SIP. 

Table 11.1: Activities to be Completed Prior to Five Year SIP Assessment 

Description Responsible Party 

Ongoing tracking of emissions for Northeast Minnesota Plan MPCA 

Analysis of NOX and SO2 emissions from taconite facilities obtained through 

Administrative Orders 

MPCA 

Remaining BART emission limit determinations for taconite facilities MPCA 

Estimation of NOX and SO2 emission limits to be obtained from 

implementation of BART for taconite facilities (compared to 2002 baseline) 

MPCA 

Incorporation of BART emission limits into facility permits MPCA 

Development of enforceable mechanism to require pilot testing of emission 

reductions/control strategies at taconite facilities 

MPCA 

Research and pilot testing into control strategies and methods to reduce 

taconite emissions 

Taconite facilities 

Reporting on outcomes of pilot testing into emission reduction methods for 

the taconite facilities 

Taconite facilities 

Evaluation of pilot test reports and determination of additional reasonable 

controls or emission reductions from taconite facilities. 

MPCA 

Determination if 2012 Northeast Minnesota Plan target is being met and 

projection if 2018 target will be met; evaluation of minor source emissions 

MPCA 

If necessary, evaluation of control strategies for sources in the Northeast 

Minnesota plan that have not otherwise investigated control strategies. 

MPCA and facilities 

Evaluation of control strategies for ICI Boilers, other point sources (such as MPCA 
113 

reciprocating engines) and mobile sources to determine if reasonable control 

strategies are available 

Contributing states 

RPOs 

Research to improve understanding of overall ammonia emissions, growth 

and control, and role of ammonia in haze formation 

EPA 

RPOs 

Evaluation of reasonable control strategies to reach an emission rate of 0.25 

lbs/MMBtu for NOX and SO2 from EGUs 

Contributing states 

Better quantification of international emissions EPA 

RPOs 

Contents of Five Year Report 

In the five year report, Minnesota will undertake an emission review in order to determine if the emission 

reductions projected to occur through the application of BART, CAIR (or a revised CAIR rule), voluntary 

control measures, and the other components of Minnesota’s long-term strategy have occurred. The 

review will also look at what new emission sources have begun operation. 

The MPCA, perhaps in conjunction with the RPOs, also hopes to assess the accuracy of the emission 

growth factors for certain SCCs, such as agricultural operations. 

Minnesota’s five year SIP report will contain the following items: 

BART Limits

As discussed in the section on the application of BART in Minnesota, although Minnesota has determined 

that BART for the taconite facilities is good combustion practices, along with some facility-specific 

measures as described, at this time the necessary information is not available to set emission limits 

associated with existing controls. Because facilities will be required to operate CEMs or undertake a 

testing method of comparable accuracy in the next few years, MPCA commits to establishing BART 

emission limits by September 2011, prior to the five year SIP report. 

More accurate emission measurements will help provide knowledge of emission formation to understand 

how modifications to operation and furnace design could result in lower NOX and SO2 emissions. The 

BART limits in conjunction with more accurate measurement of emissions will allow the MPCA to 

estimate the emission reductions that will result from BART implementation. This information will be 

provided in the five year report. 

Northeast Minnesota Plan Evaluation and Taconite Retrofit Requirements

A major portion of the five-year SIP adequacy and determination report will be an evaluation of progress 

towards meeting the Northeast Minnesota emission reduction target, described previously. The Northeast 

plan contains a target of 20% emission reductions by 2012; Minnesota will include emission inventory 

numbers to determine if this target is being met, along with future emission projections for the area to 

determine if the 30% reduction goal for 2018 will be met. 

In addition to the emission reduction target, Minnesota commits in its current long-term strategy to 

potentially require controls on taconite facilities regardless of whether the emission reduction goal is 

being met. As described previously in Chapter 10, the taconite facilities will be required to investigate 

control technologies and pollution prevention practices through pilot tests and other mechanisms, and to 

report to MPCA on feasible emission reduction strategies. MPCA will then undertake a BART-like 

review of these reports and control strategies and evaluate them based on the statutory factors and the 

status of progress towards the emission target. The five year SIP report will likely include the results of 

the analysis, a determination of any control strategies or pollution prevention projects that are reasonable 

at each of the taconite facilities, and enforceable mechanisms for requiring application of these measures. 
114 

In addition to the emission reduction measures that will be required from the taconite facilities, Minnesota 

will review emission projections for the area. If the 2012 emission target is not met, the MPCA will 

consult with FLMs, tribes, and stakeholders to consider the following information: 

• The degree to which emissions are over the 2012 target.

• Plans for emissions reductions from control upgrades or emission increases from newly 

permitted sources (in 2013-2018) that will determine if the 2018 target will be met

• The trend in ammonium nitrate and sulfate concentrations measured by monitors for 

BWCAW, VNP, and Isle Royale.

• Predicted visibility improvement in 2018 at Class I receptors as determined by modeling 

performed for the 2012 SIP Report.

• The availability of cost-effective control measures.

Based on this information and consultation, the MPCA would determine what actions need to be 

undertaken and described by the five-year SIP report. There could be many possible actions, including: 

• Assessing availability of additional cost-effective emission reductions 

• Requiring individual facilities to propose and implement some kind of available retrofit 

technology 

• Encouraging voluntary implementation of control measures

• Continued tracking of emissions and emission reduction projects and establish a year for next 

check-in, e.g. 2015 or 2018.

If the review of emissions shows that the 2012 target is met, the SIP report will assess permit applications 

approved and under review and project whether 2018 targets will be met. If it appears that the 2018 

emission target will not be met, the state will follow the same procedures as described above. If the 2012 

target is met in 2012 the 2018 is projected to be met, the state will continue to track emissions through 

2018. 

Reasonable Progress Update

It is likely that Minnesota’s Class I areas will show visibility improvement beyond the RPG set in Chapter 

10 of this SIP revision. As stated in Chapter 10, is it not clear at this time which control measures those 

states that impact Minnesota’s Class I areas are likely to find to be reasonable. The MPCA has worked 

with those states to express our opinion as to what is reasonable. 

However, the 2018 RPG set in Chapter 10 is the minimum visibility improvement that Minnesota 

considers to be reasonable. If additional control strategies are undertaken in Minnesota, the Five Year 

SIP Assessment will include enforceable measures for these strategies. In addition, between the 

submission of this SIP and the Five Year SIP assessment, Minnesota will have implemented BART 

emission limits for the taconite facilities, and will have a better sense of additional controls that will be 

taken at the taconite facilities, under the Northeast Minnesota plan, or to meet other regulatory 

requirements, such as a repromulgated CAIR rule. 

Therefore, in the Five Year SIP assessment, the MPCA will revise the RPG to reflect the further visibility 

improvement expected by 2018. This will include any additional controls strategies being implemented 

in Minnesota or surrounding states. 

Adequacy Determination

Depending on the findings of the five-year report on progress towards the goals established for each Class 

I area, Minnesota commits to determining the adequacy of this existing SIP and undertaking one of the 

actions listed in 40 CFR 51.308(h). The findings of the five-year progress report will determine which 
115 

action is appropriate and necessary, and could result in several different actions, depending on the 

progress towards the visibility goals and the location of the emissions impacting that progress. 

Should it be determined that the controls and strategies within the existing SIP are improving visibility in 

BWCAW, VNP and Isle Royale so that they are on track to meet the reasonable progress goal set in this 

SIP for 2018, Minnesota will determine that the existing SIP requires no further substantive revision in 

order to achieve established goals. Should it be determined that the controls and strategies within the 

existing SIP are improving visibility in the Class I areas so that they will exceed the RPG for 2018 set in 

this SIP, Minnesota will likely revise the RPG to show more visibility improvement expected by 2018, 

and determine that the existing SIP requires no further substantive revision. Minnesota will then provide 

to the Administrator a negative declaration, stating that further revision of the SIP (beyond the Five Year 

SIP Assessment) is not needed at this time. 

Should the MPCA determine that the strategies implemented in the existing SIP appear to be inadequate 

to ensure reasonable progress due to emissions from other states which participated in the regional 

planning process or the Northern Class I consultation process, Minnesota will provide notification of that 

fact to the Administrator and the relevant states. Minnesota will then collaborate with those states 

through the regional planning process to address the deficiencies in the SIP. 

Similarly, should Minnesota determine that the current SIP may be inadequate to ensure reasonable 

progress due to emissions from another country, the MPCA will provide such notification, along with 

available information, to the Administrator. 

If Minnesota determines that the existing SIP is inadequate to ensure reasonable progress due to 

emissions within Minnesota, the MPCA will revise its SIP within one year in order to address the plan’s 

deficiencies.