Appendix 1 - Class 1 Areas Located Within (or Impacted by) Midwest 

RPO States 
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Appendix 1 - 1 

Draft List of Class I Areas Located Within 

(or Impacted by) Midwest RPO States 

The purpose of this paper is to provide a draft list of Class I areas located within or impacted by 

a Midwest Regional Planning Organization (MRPO) State. A variety of technical analyses were 

considered in developing the draft list, including base year (2002) and future year (2018) 

modeling, back trajectories, and other data analyses. This information shows that every MRPO 

State impacts multiple Class I areas in the eastern U.S. 

Regulatory Requirements 

EPA’s regional haze rule requires a state to “address regional haze I each mandatory Class I 

Federal area located within the State and in each mandatory Class I Federal area located 

outside the State which may be affected by emissions from within the State.” (40 CFR Part 

51.308(d)) EPA has interpreted this provision as requiring a table identifying each mandatory 

Class I Federal area located within the State and each mandatory Class I Federal area located 

outside the State affected by emissions from within the State (see Draft EPA Checklist for 

Regional Haze SIPs Submitted Under 40 CFR 51.308 - 7/13/06 Staff Draft ).

Discussion 

Technical analyses conducted by the RPOs were consulted to obtain information on areas of 

influence and culpability for Class I areas in the eastern U.S.1

 A summary of this information is 

provided below and in Table 1. 

For the MRPO analyses, a state was assumed to affect visibility impairment in a Class I area if it 

contributes 2% (or more) to total light extinction. This criterion was selected based on a review 

of the back trajectory and modeling results which showed that states contributing 2% (or more) 

make-up about 90-95% of total light extinction, whereas states contributing 5% (or more) makeup only about 75-80% of total light extinction. For the other RPO analyses, deference was 

given to the criteria established by each group to identify contributing states. 

(1) MRPO Back Trajectory Analyses 

An initial trajectory analysis was conducted using data for 1997-2001 (all sampling days), a start 

height of 200 m, and a 72-hour (3-day) trajectory period (Cite: “Quantifying Transboundary 

Transport of PM2.5: A GIS Analysis”, May 2003, LADCO). By combining trajectory frequencies 

with concentration information, the average contribution to PM2.5 mass and individual PM2.5

species was estimated (which, in turn, was used to estimate the average contribution to light 

extinction). The results for 17 Class I areas in eastern U.S. were examined to identify those 

Class I areas where an MRPO state had at least a 2% contribution to total light extinction 

(based on all days). 

 

1

 Back trajectories and modeling conducted by the WRAP indicate that the Midwest RPO States are not important 

contributors to visibility impairment due to sulfates and nitrates in western Class I areas (Cite: “Attribution of Haze 

Phase I Report, Geographic Attribution for the Implementation of the Regional Haze Rule”, March 14, 2005). The 

analyses show only five groups of western Class I areas with at least 5% contribution from states outside the WRAP. 

The outside-WRAP contribution is generally small (on the order of 0-15%), and is likely due mostly to nearby 

CENRAP states.
Appendix 1 - 2 

A second trajectory analysis was conducted using data for 2000-2003 (20% highest and lowest 

days), a start height of 200m, and a 120-hour (5-day) trajectory period (Cite: “Sensitivity 

Analysis of Various Trajectory Parameters”, June 2005, LADCO). Back trajectory plots were 

prepared for each of the four northern Class I areas in Michigan and Minnesota for the high 

extinction days (see Figure 1 – note: areas in orange are mostly likely upwind and the areas in 

green are least likely upwind on poor visibility days). Although somewhat qualitative, these 

results provide additional information in identifying states impacting the northern Class I areas. 

 Voyageurs Boundary Waters 

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Figure 1. Contoured trajectory plots for poor visibility days for Class I areas in northern 

Minnesota and Michigan 

(2) MRPO PSAT Modeling 

A photochemical grid model (CAMx) was applied to provide source contribution information for 

2018 conditions. Specifically, the model estimated the impact of 18 geographic source regions 

and 6 source sectors (EGU point, non-EGU point, on-road, off-road, area, and ammonia 

sources) at Class I areas in the eastern U.S. Example results for four Class I areas (Seney, 

Mammoth Cave, Mingo, and Shenandoah) are presented in Figure 2. The results for 13 Class I 

areas in eastern U.S. were examined to identify those Class I areas where an MRPO state had 

at least a 2% contribution to total light extinction. 
Appendix 1 - 3 

Figure 2. Source region contributions to light extinction based on MRPO PSAT modeling for 

select Class I areas: Seney, Mammoth Cave, Mingo, and Shenandoah 

(3) MANE-VU Contribution Assessment 

A weight-of-evidence report was prepared by NESCAUM (on behalf of MANE-VU) to 

understand the causes of sulfate-driven visibility impairment at Class I areas in the northeastern 

and mid-Atlantic portions of the U.S. (cite: “Contributions to Regional Haze in the Northeast and 

Mid-Atlantic United States”, August 2006) The report provides information on the relative 

contribution of various emissions sources and geographic source regions. The analytical and 

assessment tools considered include Eulerian and Lagangian air quality models, and data 

analysis techniques, such as source apportionment analyses, back trajectories, and 

examination of emissions and monitoring data. Sulfate impacts were quantified using five 

analytical techniques based on 2002 conditions: REMSAD, Q/d, CALPUFF (w/ NWS data), 

CALPUFF (w/ MM5 data), and percent time upwind (based on trajectory analyses). Figure 3 

summarizes the five sets of results for three MANE-VU Class I areas. Although no specific 

criteria were identified in the report to determine a significant contribution, the States of 

Vermont, New Hampshire, Maine, and New Jersey assumed a 2% sulfate impact in recent 

letters to other states inviting them to consult on reasonable progress goals. The MRPO States 

identified as contributing to a MANE-VU Class I area were Illinois, Indiana, Michigan, and Ohio 
Appendix 1 - 4 

Figure 3. Percent contribution results using different techniques for ranking state contributions 

to sulfate levels at MANE-VU Class areas (cite: “Contributions to Regional Haze in the 

Northeastern and Mid-Atlantic Portions of the U.S.”, August 2006) 
Appendix 1 - 5 

(4) Missouri-Arkansas Contribution Assessment 

The draft Consultation Plan for the two Missouri and two Arkansas Class I areas provides 

information on source regions affecting these Class I areas (i.e., areas of influence) using a 

variety of data and analyses. (cite: “Central Class I Areas Consultation Plan”, States of Missouri 

and Arkansas, February 2007) A decision on whether a given state is a contributor to visibility 

impairment in these Class I areas was based on the combined results of three approaches: 

areas of influence (see Figure 4), PSAT modeling (based on 2018 conditions), and monitoring 

data analyses (PMF and back trajectories). According to the draft plan, if a state was a major 

contributor for at least two of the three approaches (for either sulfate or nitrate), then it was 

determined to be a significant contributor. The MRPO States identified as contributing to a 

central CENRAP Class I area were Illinois, Indiana, and Ohio. 

Figure 4. Areas of Influence for Central CENRAP Class I Areas (cite: “Central Class I Areas 

Consultation Plan”, States of Missouri and Arkansas, February 2007) 

(5) VISTAS Area of Influence Analysis 

Areas of influence (AOI) were identified for Class I areas in the southeastern U.S. using 

residence time plots based on wind trajectory direction and frequency, and weighted by visibility 

impact (light extinction by ammonium sulfate, ammonium nitrate, or elemental carbon). 

(Cite: “VISTAS Areas of Influence Analysis”, Draft, February 28, 2007). These extinctionweighted residence time analyses were overlaid on gridded emissions (for both 2002 and 2018) 

to define emission sources in the areas of greatest influence for each Class I area. Figure 5 

shows the plots for two VISTAS Class I areas. AOIs were defined on the basis of residence 

times greater than 10%. The MRPO States identified as contributing to a VISTAS Class I area 

were Illinois, Indiana, and Ohio. 
Appendix 1 - 6 

Figure 5. Areas of Influence for Shenandoah (left) and Mammoth Cave (right) for 2018 conditions 

(cite: “VISTAS Area of Influence Analyses” PowerPoint presentation, November 28, 2006) 

Note: green circles indicate 100- and 200-km radii from Class I area, red line perimeter indicate 

AOI with residence time > 10%, and orange line perimeter indicate AOI with residence time > 5% 
Appendix 1 - 7 

Table 1. Draft List of Class I Areas Impacted by MRPO States - References

AREA NAME IL IN MI OH WI 

81.401 Alabama. 

Sipsey Wilderness Area (1) (1) 

81.404 Arkansas. 

Caney Creek National Wilderness Area (2), (4) (2), (4) (2), (4) 

Upper Buffalo National Wilderness Area (1),(2),(4),(5) (2), (4) (2), (4) (2) 

 

81.408 Georgia. 

Cohotta Wilderness Area 

Okefenokee Wilderness Area 

Wolf Island Wilderness Area 

81.411 Kentucky. 

Mammoth Cave National Park (1), (2), (5) (1), (2), (5) (1), (2) (1), (2), (5) 

81.412 Louisiana. 

Breton Wilderness Area 

81.413 Maine. 

Acadia National Park (3) (3) (3) (3) 

Moosehorn Wilderness Area. (3) (3) (3) (3) 

 

81.414 Michigan. 

Isle Royale National Park (1), (2) (1), (2) (1), (2) (1), (2) 

Seney National Wilderness Area (1), (2) (1), (2) (1), (2) (1), (2) (1), (2) 

 

81.415 Minnesota. 

Boundary Waters Canoe Area National 

Wilderness Area (2) (2) (2) (1), (2) 

Voyageurs National Park (2) (2) (1), (2) 

 

81.416 Missouri. 

Hercules-Glades National Wilderness Area (2), (4), (5) (2), (4), (5) (2), (4) (2)

Mingo National Wilderness Area (2), (4), (5) (2), (4), (5) (2) (2), (4) (2)

 

81.419 New Hampshire. 

Great Gulf National Wilderness Area (3) (3) (3) (1), (3) 

Pres. Range-Dry River National 

Wilderness Area 
Appendix 1 - 8 

AREA NAME IL IN MI OH WI 

81.42 New Jersey. 

Brigantine National Wilderness Area (3) (3) (1), (3) (1), (3) 

81.422 North Carolina. 

Great Smoky Mountains NP{1} (1) (1) (1) 

Joyce Kilmer-Slickrock Wilderness Area{2} 

Linville Gorge Wilderness Area. 

Shining Rock Wilderness Area. 

Swanquarter Wilderness Area 

81.426 South Carolina. 

Cape Romain Wilderness 

81.428 Tennessee. 

Great Smoky Mountains NP{1}. (1) (1) (1) 

Joyce Kilmer-Slickrock Wilderness{2} 

81.431 Vermont. 

Lye Brook National Wilderness Area (2), (3) (2), (3) (2), (3) (1), (2), (3) 

81.433 Virginia. 

James River Face National Wilderness 

Area (2) (2) (2) (2), (5) 

Shenandoah National Park (2), (3) (1), (2), (3) (2), (3) (1),(2),(3),(5) 

 

81.435 West Virginia. 

Dolly Sods/Otter Creek National 

Wilderness Area (2), (3) (1), (2), (3) (1), (2), (3) (1),(2),(3),(5) 

Key 

(1) MRPO Back Trajectory Analyses 

(2) MRPO PSAT Modeling 

(3) MANE-VU Contribution Assessment 

(4) Missouri-Arkansas Contribution Assessment 

(5) VISTAS Areas of Influence 
Appendix 2 - Letters Requesting Participation by States with Class I Areas 
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Appendix 2 - 1 

Letters requesting Participation by States with Class I Areas

As a result of the various analyses performed by the MRPO and other RPOs, Indiana was invited 

to participate in a number of consultations regarding contributions to Class I areas. The states 

and organizations include Michigan, Minnesota, Arkansas and Missouri, Vermont, New 

Hampshire, New Jersey, and MANE-VU, also including Vermont, New Hampshire, and New 

Jersey. Copies of letters from Arkansas and Missouri, Vermont, New Hampshire, New Jersey, 

and MANE-VU follow. 

 

Indiana participated in these processes, attending meetings and calls as appropriate. 
Appendix 2 - 2 

Initial letter from Missouri and Arkansas requesting Indiana participation in their regional 

planning process for Mingo Wilderness, Hercules Glades Wilderness, Upper Buffalo 

Wilderness, and Caney Creek Wilderness areas.
Appendix 2 - 3 
Appendix 2 - 4 

Initial letter from Vermont requesting Indiana's participation in regional consultations.
Appendix 2 - 5 
Appendix 2 - 6 
Appendix 2 - 7 

Initial letter from New Hampshire requesting Indiana's participation in regional 

consultations.
Appendix 2 - 8 
Appendix 2 - 9 

Initial letter from New Jersey requesting Indiana's participation in regional consultations.
Appendix 2 - 10 
Appendix 2 - 11 
Appendix 2 - 12 

Letter from MANE VU Regional Planning Organization requesting Indiana's participation 

in regional consultations.
Appendix 2 - 13 
Appendix 2 - 14