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Draft Technical Support Document

WISCONSIN

Area Designations for the 

2010 SO2 Primary National Ambient Air Quality Standard

Summary

Pursuant to section 107(d) of the Clean Air Act, EPA must initially designate areas as either 

“unclassifiable”, “attainment”, or “nonattainment” for the 2010 one-hour sulfur dioxide (SO2) 

primary national ambient air quality standard (NAAQS). The Clean Air Act defines a 

nonattainment area as one that does not meet the NAAQS or that contributes to a violation in a 

nearby area. 

Wisconsin submitted recommendations on May 26, 2011. Table 1 below lists Wisconsin’s 

recommendations and identifies the counties or portions of counties in Wisconsin that EPA 

intends to designate “nonattainment” based on monitored violations. 

Table 1. Nonattainment Area Designation for Wisconsin

Area 

Wisconsin’s Recommended 

Designation of 

Areas/Counties

EPA’s Intended Designated 

Nonattainment Areas/Counties

Rhinelander, WI

 Oneida County (partial)

 City of Rhinelander and 

 the Towns of Crescent, 

 Newbold, Pine Lake and 

 Pelican

Nonattainment Nonattainment

Background

On June 3, 2010, EPA revised the primary SO2 NAAQS (75 FR 35520, published on June 22, 

2010). EPA revised the primary SO2 standard by establishing a new one-hour standard at a level 

of 75 parts per billion (ppb) which is attained when the three-year average of the 99th percentile 

of one-hour daily maximum concentrations does not exceed 75 ppb. EPA has determined that 

this is the level necessary to provide protection of public health with an adequate margin of 

safety, especially for children, the elderly and those with asthma. These groups are particularly 

susceptible to the health effects associated with breathing SO2. EPA is revoking the two prior

primary standards of 140 ppb evaluated over 24 hours, and 30 ppb evaluated over an entire year 

because they will not add additional public health protection given a one-hour standard at 75 

ppb. Accordingly, EPA is not designating areas in this process on the basis of either of these two 

primary standards. Similarly, the secondary standard for SO2 has not been revised, so EPA is 

not designating areas in this process on the basis of the secondary standard. 
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EPA’s SO2 Designation Approach

Section 107(d) of the Clean Air Act requires that not later than one year after promulgation of a 

new or revised NAAQS, state Governors must submit their recommendations for designations 

and boundaries to EPA by June 2011. Section 107(d) also requires EPA to provide notification 

to states no less than 120-days prior to promulgating an initial area designation that is a 

modification of a state’s recommendation. EPA was to promulgate initial area designations 

within two years of promulgation of the revised primary standard, although EPA has extended 

this deadline for one additional year due to having insufficient information to promulgate the 

designations. If a state did not submit designation recommendations, EPA will promulgate the 

designations that it deems appropriate. If a state or tribe disagrees with EPA’s intended 

designations, they have an opportunity to demonstrate why any proposed modification is 

inappropriate.

Designations guidance was issued by EPA through a March 24, 2011, memorandum from 

Stephen D. Page, Director, U.S. EPA, Office of Air Quality Planning and Standards, to Air 

Division Directors, U.S. EPA Regions I-X. This memorandum identifies factors EPA intends to 

evaluate in determining boundaries for areas designated nonattainment. These five factors 

include: 1) air quality data; 2) emissions and emissions-related data (location of sources and 

potential contribution to ambient SO2 concentrations); 3) meteorology (weather/transport patterns); 

4) geography/topography (mountain ranges or other air basin boundaries); and 5) jurisdictional 

boundaries (e.g., counties, air districts, pre-existing nonattainment areas, reservations, metropolitan 

planning organization), among any other criteria deemed to be relevant to establishing appropriate 

area designations and boundaries for the one-hour SO2 NAAQS.

The March 24, 2011, memo recommended that area boundaries default to the county boundary unless 

information provided by the state or tribe justifies a larger or smaller boundary than that of the 

county. EPA believes it is appropriate to evaluate each potential area on a case-by-case basis, and to 

recognize that area-specific analyses conducted by states, tribes and/or EPA may support a differing 

boundary than a county boundary.

In this technical support document, EPA discusses its review and technical analysis of the 

recommendations regarding areas with monitored violations submitted by Wisconsin for designations 

for the one-hour SO2 standard and any modifications from these recommendations.

Definition of important terms used in this document:

1) Designated nonattainment area – an area which EPA has determined, based on a state 

recommendation and/or on the technical analysis included in this document, has violated the 

2010 SO2 NAAQS, based on the most recent three years of air quality monitoring data, or 

contributes to a violation in a nearby area. 

2) Recommended nonattainment area – an area a state or tribe has recommended that EPA 

designate as nonattainment.
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3) Violating monitor – an ambient air monitor meeting all methods, quality assurance and siting 

criteria and requirements whose valid design value exceeds 75 ppb, as described in Appendix T 

of 40 CFR part 50.

4) 2010 SO2 NAAQS – The NAAQS for SO2 promulgated in 2010. This NAAQS is 75 ppb, 

based on the three year average of the 99th percentile of the annual distribution of daily 

maximum one-hour average concentrations. See 40 CFR Part 50.17.

5) Design Value - a statistic computed according to the data handling procedures of the NAAQS 

(in 40 CFR 50 Appendix T) that, by comparison to the level of the NAAQS, indicates whether 

the area is violating the NAAQS.

Technical analysis for the Rhinelander, WI Area

Introduction 

This technical analysis for the Rhinelander Area identifies Oneida County with a monitor that 

violates the 2010 SO2 NAAQS, and evaluates nearby counties for contributions to SO2

concentrations in the area. EPA has evaluated this county and nearby counties based on the 

evidence for the factors recommended in the March 24, 2011 EPA guidance.

Figure 1 is a map of the area showing the locations and design values of air quality monitors in 

the area, and the counties surrounding any violating air quality monitors.
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Figure 1. Map of sources and monitors in the Rhinelander, WI area and the intended 

Rhinelander nonattainment area

For the Rhinelander, WI Area, Wisconsin recommended that part of Oneida County containing 

the City of Rhinelander and the Towns of Crescent, Newbold, Pine Lake, and Pelican be 

designated as nonattainment for the 2010 SO2 NAAQS. Based on EPA's technical analysis 

described below, EPA agrees with the State’s recommendation and intends to designate this area 

also listed in Table 1 as nonattainment for the 2010 SO2 NAAQS. 

Detailed Assessment

Air Quality Data 

Wisconsin’s recommendation was based on data indicating nonattainment at an SO2 monitor

located in Rhinelander, Oneida County. The SO2 NAAQS design value representative of the 

Rhinelander area is shown in Table 2. The Oneida County monitor shows a violation of the 2010 

SO2 NAAQS for 2009-2011. Therefore, at least a portion of this county must be designated 

nonattainment. 
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Table 2. Air Quality Data for Nonattainment Designations in Wisconsin

County

State

Recommended 

Nonattainment?

Monitor Air Quality 

System ID Monitor Location SO2 Design Value, 2009-2011 (ppb)

Oneida Yes 55-085-0996 Rhinelander 

Water Tower 151

Emissions and Emissions-Related Data

Evidence of SO2 emissions sources in the vicinity of a violating monitor is an important factor 

for determining whether a nearby area is contributing to a monitored violation. For this factor, 

EPA evaluated county level emission data for SO2. Table 3 shows total emissions of SO2 (given 

in tons per year) for violating and potentially contributing counties in and around the 

Rhinelander area and sources emitting (or anticipated to contribute) greater than 100 tons per 

year of SO2. The county that contains the Rhinelander nonattainment area for the 2010 SO2

NAAQS is shown in bold. Wisconsin believes Wausau Paper Mills, LLC (Wausau Paper), is 

likely to be the primary cause of this NAAQS violation. This facility is less than one kilometer 

from the air quality monitor. There are very few other SO2 sources in Oneida County. The 

nearest source over 100 tons per year is located 33 kilometers from the Rhinelander air quality 

monitor, in Lincoln County. It emits only slightly more SO2 than Wausau Paper does, and its 

distance from the monitor indicates that it is unlikely to have a significant impact on the 

monitored violation of the SO2 NAAQS. Therefore, EPA finds that this source may be judged 

not to contribute to the monitored violation.

Table 3. SO2 Emissions

County

Facility Located in 

StateRecommended 

Nonattainment Area?

Facility Name – Total SO2 Air

Emissions [NEI08V2]

(tons per year)

Facility 

Location/ 

Distance from 

Monitor (km)

Total County 

SO2 Emissions 

(tons per year)

Oneida County Yes Wausau Paper Mills, LLC –3071 Rhinelander/ 0.7 3128 Yes Red Arrow Foods –8 Rhinelander/ 4.5

Lincoln County No Packaging Corp. of America –4641 Tomahawk/ 33. 4690

Emission Controls

The emissions data provided in Table 3 represent emissions levels taking into account any 

control strategies implemented on stationary sources in the Rhinelander area up to and including 

2008. EPA does not have any additional information on actual emissions reductions resulting 

from controls put into place after 2008. Wisconsin is currently working with Wausau Paper to 

reduce its SO2 emissions. 

Geography/Topography (mountain ranges or other air basin boundaries)

Oneida County does not have any geographical or topographical barriers significantly limiting 

air pollution transport within its airshed. Therefore, this factor did not play a significant role in 

determining the nonattainment boundary.

Meteorology (weather/transport patterns)
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For this area, winds can be from any direction. Therefore, sources in all directions can have 

some potential contribution. Given that the dominant SO2 source is less than one kilometer from 

the air quality monitor, meteorology is not considered to be a significant factor in defining this 

nonattainment area.

Tribal Recommendations

On May 10, 2011, the Forest County Potawatomi Community (FCPC) submitted its SO2

designation recommendations to EPA. The FCPC has jurisdiction over parcels of land in several 

Wisconsin counties, including Oneida County. The Oneida County land parcel which belongs to 

the FCPC is located about 16 miles (26 kilometers) east of Wausau Paper. The FCPC 

recommended that its Oneida County land parcel be designated “unclassifiable” for the 2010 SO2

NAAQS, which is compatible with Wisconsin’s recommendation that that portion of the county 

be designated attainment. However, EPA at present is only designating the portion of Oneida 

County that is to be designated nonattainment and is not designating the portion of the county to 

which FCPC’s recommendations apply.

Conclusion

The air quality monitor in Oneida County shows a violation of the 2010 SO2 NAAQS, based on 

2009-2011 air quality data. Source proximity suggests that Wausau Paper in Rhinelander, 

Wisconsin is likely the dominant contributor to SO2 NAAQS violations at the Rhinelander SO2

monitor. After considering the factors described above, EPA intends to designate the portion of 

Oneida County containing the City of Rhinelander and the Towns of Crescent, Newbold, Pine 

Lake, and Pelican, as the Rhinelander, WI nonattainment area for the 2010 SO2 NAAQS, as 

recommended by Wisconsin.