1

---------------------------------------------------------------------------------------------------------------------

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 

“nonattainment,” “attainment,” or “unclassifiable” 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 designation recommendations on May 26, 2011. On February 6, 2013, 

EPA sent a letter to Wisconsin describing the intended nonattainment designations. Wisconsin

responded with further recommendations on April 8, 2013. Table 1 below lists Wisconsin’s

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

initially designating “nonattainment” based on monitored violations. EPA is not yet prepared to 

designate other areas in Wisconsin, and will address those areas in future final designation

actions.

Table 1. Nonattainment Area Designation for Wisconsin

Area Wisconsin’s Recommended 

Designation of Areas/ Counties

EPA’s Nonattainment 

Designation of Areas/Counties

Rhinelander, WI

 Oneida County (partial)

 City of Rhinelander and the 

 Towns of Crescent, Newbold,

 Pine Lake and Pelican

May 26, 2011: Nonattainment

April 8, 2013: Delay final 

nonattainment designation

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 met at an ambient air quality monitoring site when the 

three-year average of the 99th percentile of one-hour daily maximum concentrations does not 

exceed 75 ppb, as determined in accordance with Appendix T of 40 CFR part 50. (40 CFR 

50.17(a)-(b).) 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 
2

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.

EPA’s SO2 Designation Approach

Section 107(d) of the Clean Air Act provides 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. For the 2010 SO2 NAAQS, this deadline was June 3, 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. If a 

state did not submit designation recommendations, EPA is promulgating the designations that it 

deems appropriate. If a state or tribal government disagreed with EPA’s intended designations, it 

was given 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 information deemed to be 

relevant to establishing appropriate area designations and boundaries for the one-hour SO2

NAAQS.

The March 24, 2011, guidance 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 caseby-case basis, and to recognize that area-specific analyses conducted by states, tribes and/or EPA 

may support a different 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. 
3

2) Recommended nonattainment area – an area that a state or tribal government has 

recommended to EPA to be designated as nonattainment.

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 designations 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.
4

Figure 1. Map of sources and monitors in the Rhinelander, WI area and the Rhinelander

nonattainment area

On May 26, 2011, 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. On February 6, 2013, EPA stated its intention to 

designate this portion of Oneida County as the Rhinelander, WI nonattainment area. Wisconsin 

responded in an April 8, 2013 letter that the main SO2 source in Rhinelander had applied in 

January 2013 to install a natural gas boiler. Wisconsin’s letter requested that EPA delay 

finalizing the nonattainment designation, stating its view that emission reductions at this source 

would lead to attainment of the 2010 SO2 NAAQS. 

EPA must base this action on the current air quality status and may not base its action on future 

anticipated changes in air quality status. Current emissions and monitoring data indicate that a 

portion of Oneida County should be designated nonattainment. An application to install 

equipment to address SO2 emissions does not signify that Oneida County is currently attaining 

the 2010 SO2 NAAQS. Therefore, based on EPA's technical analysis described below, EPA is 

initially designating the originally recommended Rhinelander area as nonattainment for the 2010 

SO2 NAAQS. This area is described in Table 1. Areas and sources that we are not yet prepared 

to conclude are contributing to the monitored violations or to other possible violations are not 

included in this initial nonattainment area, and will be addressed in a future final designations 

action.
5

Detailed Assessment

Air Quality Data 

This factor considers the SO2 air quality monitoring data, including the design values (in ppb) 

calculated for all air quality monitors in Oneida County in the Rhinelander area based on data for 

the 2009-2011 period. Wisconsin’s May 26, 2011 designation 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. 

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 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 asserts that 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 suggests that it is less likely to be contributing to the monitored violation of the SO2

NAAQS. EPA is not yet prepared to conclude that the emissions from the source in Lincoln 

County contribute to the monitored violation or to other possible violations, and will further 

address this source in a future final designation action.

Table 3. SO2 Emissions

County Facility Located in 

StateRecommended 

Nonattainment Area?

Facility Name – Total SO2 Air

Emissions [NEI08V3]

(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 3131 Yes Red Arrow Foods –8 Rhinelander/ 4.5

Lincoln County No Packaging Corp. of America –4641 Tomahawk/ 33. 4689
6

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, as described in its April 8, 2013 letter.

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)

Evidence of source-receptor relationships between specific emissions sources and high SO2

values at violating monitors is another important factor in determining the appropriate 

contributing areas and the appropriate extent of the nonattainment boundary. Figure 2 shows the 

prevalent wind directions for the Rhinelander area.

Figure 2: Wind Rose for Rhinelander, WI

Source: WDNR Software: WRPLOT-Lakes Environmental Software
7

For this area, winds can come from any direction, but winds from the west and southwest are the 

most frequent. 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. 

Jurisdictional boundaries

Once the geographic area associated with the area violating the SO2 standard and the nearby 

areas contributing to the violations are determined, we considered existing jurisdictional

boundaries for the purpose of providing a clearly defined legal boundary for carrying out the air 

quality planning and enforcement functions of the area. Wisconsin did not have any 

nonattainment areas under the prior SO2 NAAQS. The nonattainment area boundary

recommended by Wisconsin is made up of a city and towns with contiguous boundaries, which 

contain the SO2 source contributing to the monitored violations and the SO2 ambient air quality 

monitor. EPA finds that city and town boundaries in Wisconsin provide a suitable administrative 

basis for formulating nonattainment area boundaries.

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 that belongs to 

the FCPC is located about 16 miles (26 kilometers) east of Wausau Paper and is outside of the 

geographic boundaries of the Rhinelander nonattainment area that is addressed in this technical 

support document. Currently, there are no violations of the 2010 SO2 NAAQS in FCPC land 

parcels. EPA is not yet prepared to designate these parcels and will address the FCPC lands in a 

future final designation action.

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. Although Wisconsin has stated that a recent permit application will lead to reduced 

SO2 emissions, EPA believes that Oneida County is presently violating the SO2 NAAQS. 

Therefore, EPA is designating 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 originally recommended by Wisconsin in its 

May 26, 2011 letter. Based on the above factor analysis, EPA is not yet prepared to conclude 

that the emissions from sources located outside of this boundary contribute to the monitored 

violation or to other possible violations. In a subsequent round of designations, we will make 

final designation decisions for areas in Wisconsin that are not included in the nonattainment area 

designation addressed in this technical support document.