## Memorandum

To: Docket

From: Kristin Hall, Air Planning Team, EPA Region 10

Re: Technical Support Document

- Idaho State Implementation Plan and Interstate Transport Requirements for the 2006 24

- hour Fine Particulate Matter National Ambient Air Quality

Standards

Date: January 22

, 201 5

Recommendation

Based on the weight of the evidence evaluated in this Technical Support Document (TSD)

, it is recommend ed the EPA propose approval of the Idaho State Implementation Plan (SIP) as adequately addressing the interstate transport requirements of CAA section

1 10(a)(2)(D)(i)(I) for the 2006 24

- hour PM 2.5 N ational Ambient Air Quality Standards (NAAQS ). This section of the CAA requires that the Idaho SIP contain adequate provisions prohibiting emissions which will contribute significantly to nonattainment in, or interfere with maintenance by, any other state with respect to the 2006 24

- hour PM 2.5 NAAQS

. T he Idaho S IP meets these CAA requirements as detailed below.

This TSD is organized as follows:

Table of Contents

I. Interstate Transport and Idaho

A. Summary of Proposed Action

B

. Summary of Idaho Submittal

C. Summary of EPA Evaluation and Conclusion

II. Transport Assessment Methodology

A. Discussion of Nona ttainment and Maintenance Receptor Selection Methodology

B . Factors Considered in Transport Analysis for Nonattainment and Maintenance
Receptor s

I II . Transport Assessment for Nona ttainment Receptors

A. Introduction
B. Transport to Western States

1

. California

2

. Montana3

. Oregon

4. Utah

C . Transport to Eastern States

I V. Transport Assessment for Maintenance R eceptors

A. Introduction

B

. Transport to Western States

1

. California

2

. Montana

3

. Utah

C . Transport to Eastern States

V. Appendix

– PM 2.5 IMPROVE Data

1. Overview of IMPROVE Monitoring Network Sites

2. Idaho and Idaho/Oregon Border

- IMPROVE Data for the Years 2009

- 2013

3. Montana

- IMPROVE Data for the Years 2009

- 2013

4 . Nevada

- IMPROVE Data for the Years 2009

- 2013

5

. Utah

- IMPROVE Data for the Years 2009

- 2013
6. Wyoming

- IMPROVE Data for the Years 2009

- 2013

7 . California/Oregon Border

- IMPROVE Data for the Years 2009

- 2013

8. Oregon/Washington Border

- IMPR OVE Data for the Years 2009

- 2013

I . Interstate Transport and Idaho

I. A. Summary of Proposed Action

Background:

Section 110(a) (1) of the Clean Air Act ( CAA ) requires each state to submit to the Environmental Protection Agency (EPA), within three years (or such shorter period as the Administrator may prescribe) after the promulgation of a primary or secondary National Ambient Air Quality Standard (NAAQS) or any revision ther eof, a State Implementation Plan (SIP) that provides for the “implementation, maintenance, and enforcement” of such NAAQS. The EPA refers to these specific submittals as “infrastructure” SIPs because they are intended to address basic structural SIP requir ements for new or revised NAAQS. For the 2006 24

- hour PM 2.5 NAAQS, these infrastructure SIPs were due on September 21, 2009

.

2CAA s ection 110(a)(2) includes a list of specific elements that “[ e ] ach such plan submission”

must meet. The interstate transport provisions in CAA section 110(a)(2)(D)(i) (also called “good neighbor” provisions) require each state to submit a SIP that contains adequate provisions prohibiting air emissions that will have certain adverse air quality effects in other states. CAA section 110(a)(2)(D)(i) identifies four distinct elements related to the impacts of air pollutants transported across state lines. In this action, the EPA is addressing the first two elements of this section, spe cified at CAA section 110(a)(2)(D)(i)(I)

– the requirement that a state SIP :

“ contain adequate provisions

—

(i) prohibiting, consistent with the provisions of this subchapter, any source or other type of emissions activity within the State from emitting any air pollutant in amounts which

will

—

(I) contribute significantly to nonattainment in, or interfere with maintenance by,
any other State with respect to any such national primary or secondary
ambient air quality standard ”

On June 2 8

, 2010, the State of I daho submitted a SIP revision to address the interstate transport

SIP requirements of CAA section 110(a)(2)(D)(i) (Idaho 2010 Interstate Transport submittal)

. 1

The submittal included documentation of a public comment period from May 11, 2010

, through

June 10, 2010 and opportunity for public hearing. We find that the process followed by the State in adopting the SIP submittal complies with the procedural requirements for SIP revisions under

CAA section 110 and the EPA’s implementing regulations.

Proposed A ction:

In this action, we are proposing to approve the Idaho SIP as adequately addressing the requirements of CAA section 110(a)(2)(D)(i)(I) for the 2006 24

- hour PM 2.5 NAAQS. We

believe that it is reasonable to conclude that, based on the weight of the evidence, emissions from

sources in Idaho do not significantly contribute to nonattainment or interfere with maintenance

of the 2006 24

- hour PM 2.5 NAAQS in any other state, with the foll owing possible and limited exception. We are unable to determine at t his time, based on the weight of the evidence , whether

emissions from Idaho significantly contribute to nonattainment of the 2006 24

- hour PM 2.5 NAAQS in Utah for purposes of the interstate transport requirements of CAA section 110(a)(2)(D)(i)(I) . This is because the Cache Valley, a relatively isolated and geographically

1 The Idaho 2010 Interstate Transport submittal addresses the interstate transport requirements of the 1997 and 2008 ozone NAAQS and the 1997 and 2006 PM 2.5 NAAQS. In this action, the EPA is only taking action with respect to CAA section 110(a)(2)(D)(i)(I) for the 2006 PM 2.5 NAAQS. The EPA has addressed CAA section 110(a)(2)(D)(i)(II) for the 2006 PM 2.5 and 2008 ozone NAAQS in a se parate action (July 14, 2014, 79 FR 40662 ). In addition, we previously approved the Idaho SIP for 110(a)(2)(D)(i) with respect to the 1997 PM 2.5 and 1997 ozone NAAQS on November 26, 2010 (75 FR 72705). Finally, we will address the requirements of CAA section 110(a)(2)(D)(i)(I) with respect to the 2008 ozone NAAQS in a future action.

3discrete mountain valley that straddles the Utah

- Idaho border, experiences elevated 24

- hour

PM 2.5 levels in the airshed as a whole

. 2

In the event th at emissions from Idaho sources do significantly contribute to nonattainment in

Utah with respect to the Cache Valley, we have evaluated available technical information and recently

- approved controls that address PM 2.5 emissions on the Idaho side of the Cache Valley

. We are proposing t o find th at th e current Idaho SIP adequately addresses the requirements of CAA section 110(a)(2)(D)(i)(I) for the 2006 24

- hour PM 2.5 NAAQS . Any cost

- effective controls reasonably available to Idaho to address any potential contribution to nonattainment or interference with maintenance with respect to the requirements of CAA section 110(a)(2)(D)(i)(I) for the 2006 24

- hour PM 2.5 standard in the Utah portion of Cache Valley are being implemented . This proposed approval neither constitutes a determination tha t Idaho is significantly contributing to nonattainment in Utah, nor quantifies Idaho’s obligations pursuant to CAA section 110(a)(2)(D)(i)(I).

We note that

, in this action

, we do not propose to make any determination with respect to the requirements of pa rt D

, title I of the CAA, and state obligations for attainment planning being conducted by Idaho and Utah for the cross

- state Logan UT

- ID nonattainment area ( comprised of portions of Cache County, Utah and Franklin County, Idaho, also known as the Cache Va lley nonattainment area). 3 The requirements of part D

, title I of the CAA

, for the Logan UT

- ID

nonattainment area will be addressed by the EPA in a separate action.

I. B

. Summary of Idaho Submittal

On June 2 8

, 2010, the State of Idaho submitted a SIP revision to address the interstate transport

SIP requirements of CAA section 110(a)(2)(D)(i) (Idaho 2010 Interstate Transport submittal)

. 4
Here we summarize the information provided in t he Idaho 2010 Interstate Transport submittal specifically addressi ng the requirements of CAA section 110(a)(2)(D)(i)(I) for the 2006 24

- hour

PM 2.5 NAAQS. 5

In the submittal, Idaho cited the Rules for the Control of Air Pollution in Idaho, and stated that these rules contain provisions prohibiting any sources or type of emission activity within the State from emitting any air pollutant in any amounts that will contribute significantly to nonattainment in any other state with respect to the 2006 24

- hour PM 2.5 NAAQS. The submittal specifically cited Idaho regulations at IDAPA 58.01.01.203.02 which require any owner or

2 On November 13, 2009, p ortions of Cache Count y, Utah and Franklin County, Idaho were designated by the EPA

as nonattainment for the 2006 24

- hour PM 2.5 NAAQS ( Logan UT

- ID nonattainment area or Cach e Valley) (74 FR

58688 ).

3 Ibid.

4 2010 Idaho Interstate Transport Submittal, Idaho Department of Environmental Quality. June 28, 2010.

5 The submittal addresses the interstate transport requirements of the 1997 and 2008 ozone NAAQS and the 1997

and 2006 PM 2.5 NAAQS. In this action, the E PA is only taking action with respect to CAA section 110(a)(2)(D)(i)(I) for the 2006 PM 2.5 NAAQS. The EPA has addressed CAA section 110(a)(2)(D)(i)(II) for the

2006 PM 2.5 and 2008 ozone NAAQS in a separate action (proposal March 26, 2014, 79 FR 16711). I n addition, we previously approved the Idaho SIP for 110(a)(2)(D)(i) with respect to the 1997 PM 2.5 and 1997 ozone NAAQS on November 26, 2010 (75 FR 72705). Finally, we will address the requirements of CAA section 110(a)(2)(D)(i)(I) with respect to the 200 8 ozone NAAQS in a future action.

4operator of a proposed new source, whether major or minor, to demonstrate to the satisfaction of the Idaho Department of Environmental Quality (DEQ) that the proposed source’s projected

emissions will not c ause or significantly contribute to a violation of any NAAQS. The submittal stated that this demonstration is not constrained to impacts solely in Idaho. For example, Idaho specified in the submittal that all estimates of ambient concentrations must be b ased on the requirements of 40 CFR part 51, Appendix W which look to the point of maximum concentration, not a jurisdictional boundary. The submittal pointed to the incorporation by

reference of the Federal 2006 24

- hour PM 2.5 NAAQS in the Idaho SIP , and t he implementation

of the 2006 24

- hour PM 2.5 standard and New Source Review (NSR) requirements for this

standard.

In addition, at IDAPA 58.01.01.401.03, the submittal described Idaho DEQ authority to require a Tier II operating permit if (a) emission ra te reductions are necessary to attain or maintain any NAAQS or applicable prevention of significant deterioration increment; or (b) specific emission standards, or requirements on operation or maintenance are necessary to ensure compliance with any applica ble emission standard or rule. As part of the Tier II permitting process, the facility operator (or responsible official) must demonstrate the source does not cause or significantly contribute to a violation of any NAAQS. Idaho’s submittal noted that the State has used this authority in the past as part of a suite of control measures implemented to address nonattainment and other air quality issues in the past. The submittal also cited the Crop Residue Burning Program development as an example of how Idah o has worked with other states and with tribes to ensure that an Idaho activity would not contribute significantly to nonattainment in, or interfere with maintenance by, any other state with respect to any NAAQS.

The Idaho 2010 Interstate Transport subm ittal also analyzed Technical Support Documents ( TSDs ) from areas in surrounding states thought to be experiencing problems attaining and maintaining the 2006 24

- hour PM 2.5 NAAQS, including: Tacoma, Washington; Klamath Falls, Oregon; Oakridge, Oregon; Salt Lake City, Utah; Provo, Utah; Clark County, Nevada; Wasatch Front, Utah; Upper Green River Basin, Wyoming; and Libby, Montana. 6 These TSDs were developed durin g the designations process for the 2006 24

- hour PM 2.5 NAAQS under part D, title

I of the CAA

. 7 I daho asserted that this information also helps to evaluate potential interstate transport impacts.

The submittal also included technical information from the Western Regional Air Partnership (WRAP) Technical Support System, including the source apportio nment feature of this tool which provides information regarding expected PM 2.5 impacts due to sources in Idaho. The submittal asserted that combining this with measured impacts at monitors in National Parks and wilderness areas ( c lass I areas ) which provid es information on backgr ound levels , helps to evaluate whether transported emissions from Idaho sources interfere with 2006 24

- hour PM 2.5 NAAQS maintenance efforts in other states.

6 These TSDs were submitted as supporting documentation to the 2010 Idaho Interstate Transport Submittal, Idaho Department of Environmental Quality. June 28, 2010.

7 The EPA designated areas nonattainment for the 2006 24

- h our PM 2.5 NAAQS on November 13, 2009 (74 FR 58688).

5Specifically, the submittal asserted that winter

- time high pressure system s with weak transport

and near calm surface winds are characteristic of 2006 24

- hour PM 2.5 NAAQS exceedances in

the west

– as evidenced in the TSDs of surrounding areas submitted as part of the Idaho

submittal. 8 The submittal stated that for these winter

- time inversion events that lead to exceedances, transported PM 2.5 and precursors from outside the local cold pool is small to

nonexistent and is not generally a contributing factor to PM 2.5 concentrations in these western
exceedances areas. Idaho assert ed that l ow winter transport of PM 2.5 and its precursors is supported by the monitoring data at National Parks and wilderness areas ( IMPROVE monitoring

network )

. 9 Specifically, Idaho stated that m ost of the IMPROVE monitors in the areas surrounding Idaho sh ow distinct seasonal variation with the lowest concentrations in the

winter. 10 In addition, the WRAP monitoring and apportionment data provides insight into how Idaho sources may influence PM 2.5 concentrations in surrounding states. Most of the IMPROVE

mo nitoring sites evaluated in the submittal have annual averages below 5 μ g/m 3 . For most of the Class I areas downwind of Idaho that were evaluated, the highest fractional contribution from Idaho sources occurs on the 20% Best Visibility Days (i.e. days cha racterized by the least amount of light

- scattering particulate matter in the air). The submittal asserted that this illustrates the need for sufficient wind to transport pollutants from the populated lowlands in Idaho up and over significant elevations to the monitors in these c lass I areas.

The submittal highlighted the specific facts and circumstances of the Cache Valley, a mountain valley which straddles the Utah

- Idaho border. The Cache Valley is a bowl

- shaped valley measuring approximately 60 kilometers north to south and 20 kilometers east to west. The Idaho

submittal stated that while the Cache Va lley is a shared airshed between Utah and Idaho and sources on both sides of the valley contribute to elevated PM 2.5 levels in the valley as a whole, transport of emissions from surrounding areas of Idaho, Utah and Wyoming do not contribute significantly t o nonattainment in the Cache Valley because of the unique topograph y and meteorology of the v all ey. Idaho’s submittal indicated that the State wa s working directly with Utah and EPA Regions 8 and 10 under a two

- state, one airshed approach to address the 2 006 24

- hour PM 2.5 nonattainment problems in the Logan UT

- ID nonattainment area

. 11

The Idaho submittal concluded that

, based on the weight of the evidence, specifically:

• the low concentrations of daily PM 2.5 measured at IMPROVE monitors surrounding Idaho during

times that exceedances occur

,

• the small contributions to IMPROVE monitored values from Idaho emission sources, and

8 These TSDs were submitted as supporting documentation to the 2010 Idaho Interstate Transport Submittal, Idaho Department of Environmental Quality. June 28, 2010.

9 The Interagency Monitoring of Protecte d Visual Environments (IMPROVE) program is a cooperative measurement effort governed by a steering committee composed of representatives from Federal and regional

- state organizations. The IMPROVE monitoring program was established in 1985 to aid the creation of Federal and State implementation p lans for the protection of visibility in c lass I areas. The objectives of IMPROVE include establishing current aerosol conditions in mandatory class I areas; and identifying chemical species and emission sources responsible for existing man

- made visibi lity impairment.

10 2010 Idaho Interstate Transport Submittal, Idaho Department of Environmental Quality. June 28, 2010.

11 The EPA designated areas nonattainment for the 2006 24

- hour PM 2.5 NAAQS on November 13, 2009, including the Logan UT

- ID nonattainment area, commonly referred to as the Cache Valley nonattainment area (74 FR 58688).

6• the significant role meteorology and topography play in the conditions that lead to 24

- hour PM 2.5 NAAQS v iolations in Idaho and surrounding states

,

the Idaho SIP adequately addresses the interstate transport requirements of the CAA for the 2006

24

- hour PM 2.5 NAAQS, while treating the Cache Valley as a separate , cross

- border valley with

distinct topography and meteorology that impacts the air quality of the area during specific

weather events.

I. C

. Summary of EPA Evaluation and Conclusion

T o determine whether the CAA section 110(a)(2)(D)(i)(I) requirement is satisfied , the EPA must

determine whether a s tat e’s emissions contribute significantly to nonattainment or interfere with

maintenance in other states

. If this factual finding is in the negative, then CAA section 110(a)(2)(D)(i)(I) does not require any substantive changes to a state’s SIP to impose addi tional emissions controls to alleviate interstate transport

. Consistent with the EPA ’ s approach in the

eastern United States ( 1998 NOx SIP c all , the 2005 CAIR

, and the 2011 Transport Rule ), we are evaluating potential interstate transport from Idaho to other states with respect to specific

monitors identified as having nonattainment and/or maintenance problems, which we refer to as “receptors.” 12

It is important to note that on August 21, 2012, the U.S. Court of Appeals for the DC Circuit

issued a deci sion to vacate the Transport Rule. See EME Homer City Generation, L.P. v. E.P.A.,

696 F.3d (DC Cir. 2012) cert. granted , 2013 U.S. Lexis 4801 (2013). The DC Circuit also

ordered the EPA to continue implementing CAIR in the interim. However, on April 29, 2014, the U.S. Supreme Court reversed and remanded the D.C. Circuit’s ruling and upheld the EPA’s approach in the Transport Rule. EPA v. EME Homer City Generation, L.P ., 134 S.Ct. 1584 (2014). The Supreme Court generally upheld the EPA’s approach in the Transport Rule for the issues in front of the Supreme Court for review

, and on October 2 3 , 2014, the DC Circuit lifted the stay on the Transport Rule. 13

While our evaluation is consistent with the Transport Rule approach, t he State of Idaho was n ot covered by either CAIR or the Transport Rule, and the EPA made no determinations in either rule regarding whether emissions from sources in Idaho significantly contribute to nonattainment

or interfere with maintenance of the 2006 24

- hour PM 2.5 NAAQS in another state , nor did it attempt to quantify Idaho’s obligation

. 14

Evaluation :

In this action, w e have evaluated the information available and have determined that no single piece of information is by itself dispositive of the issue. As region

- wide modeling such as exists for the Transport Rule of the 2006 24

- hour PM 2.5 NAAQS for the western portion of the United States, including Idaho, is not available for this particular NAAQS , we believe that it is

12 See NO

x SIP Call, 63 FR 57371 (October 27, 1998); CAIR, 70 FR 25172 (May 12, 2005); and Transport Rule or
Cross

- State Air Pollution Rule, 76 FR 48208 (August 8, 2011).

13 USCA Case #11

- 1302, Document # 1518738, Filed 10/23/2014.

14 Ibid.

7appropriate to evaluate the total weight of all the evidence which, taken together can be used to

evaluate whether Idaho emissions significant ly contribut e to nonattainment or interfere with

maintenance of the 2006 24

- hour PM 2.5 NAAQS in any other state

. See, Guidance on the U se of Models and Other Analyses for Demonstrating Attainment of Air Quality Goals for Ozone, PM2.5, and Regional Haze, EPA

- 454/B

- 07

- 002, April 2007

.

We believe that the Idaho 2010 Interstate Transport submittal and other supplemental evidence explained h erein provides important information on the meteorology (including temperature inversions, mixing zones, and the like, for example) , topography, geography, background levels, and technical analysis of violating areas in surrounding states and that this inf ormation generally

supports a conclusion that emissions from sources in Idaho do not significantly contribute to
nonattainment or interfere with maintenance of the 2006 24

- hour PM 2.5 NAAQS in any other

state , with the exception of Utah with respect to the Cache Valley. In order to reach a proposed conclusion, we believe it is necessary to supplement the information provided in the Idaho 2010 Interstate Transport submittal with a review of the monitors in other states that are appropriate

nonattainmen t and maintenance receptors.

We also have reviewed monitor ing data collected at National Parks and wilderness areas (class I areas) in the west which we believe may be considered representative of background ( data provided in s ection V. Appendix to this TSD). In addition, we have review ed technical

documentation produced by the EPA and states during the designations and attainment planning

processes for the 2006 24

- hour PM 2.5 NAAQS under part D , title I of the CAA . This technical

documentation addresses atmos pheric science, meteorology, topography and sources of PM 2.5 in Idaho and surrounding states in the west . While this information was developed for SIPs under part D, title I of the CAA, we believe the information help s inform our evaluation of interstate transport requirements at CAA section 110(a)(2)(D)(i)(I) for the 2006 24

- hour PM 2.5 NAAQS

.

Finally, we have evaluate d revisions to the Idaho SIP that have been made since the Idaho 2010 Interstate Transport submittal. These revisions were submitted to control emissions of PM 2.5 on the Idaho side of the Cache Valley

– a mountain valley that straddles the Utah

- Idaho border , a portion of which has been designated nonattainment for the 2006 24

- hour PM 2.5 NAAQS

. 15 Our supplemental analysis is provided in s ec tions II and III below.

Conclusion:

Based on the following weight of the evidence , we propose to conclude that the Idaho SIP meets the requirements of CAA section 110(a)(2)(D)(i)(I) for the 2006 24

- hour PM 2.5 NAAQS:

• The evidence in the 2010 Idaho Interstate Transport submittal that shows the low concentrations

of PM 2.5 m easured at National Parks and wilderness areas surrounding Idaho, the small

contributions at those monitors from Idaho emission sources, and the significant role meteorol ogy and topography play in the conditions that lead to violations of the 24

- hour PM 2.5 standard in
Idaho and surrounding western states

.

15 The EPA designated the Logan UT

- ID area as nonattainment for the 2006 24

- hour PM 2.5 NAAQS on November
13, 2009 (74 FR 58 688). This area is commonly referred to as the Cache Valley nonattainment area.

8• The evidence from monitor ing data collected at National Parks and wilderness areas (class I

areas) in the west that indicates there are low background levels of PM 2.5 in class I areas located
between Idaho and identified receptors , and in the west in general, at the times when violations in
the west typically occur (winter months )

.

• The evidence from technical support documents produced by the states and the EPA through the
designations and attainment planning process for the 2006 24

- hour PM 2.5 NAAQS that indicates

violations of the 24

- hour PM 2.5 standard in the western states are generally driven by wintertime
inversion meteorology in areas impacted by major mountain ranges including the Cascade Range

, the W asatch Front, the Sierra Nevada Range , and other significant topography.

• The evidence in the current Idaho SIP that shows Idaho has adopted and i mplemented measures

to specifically control PM 2.5 emissions from sources on the Idaho side of the Cache Valley that
may be significantly contributing to nonattainment on the Utah side of the Cache Valley

– a mountain valley straddling the Utah

- Idaho border that is influenced by distinct meteorology and
topography

.

II. Transport Assessment Methodology

II. A. Discussion of Nona ttainment and Maintenance Receptor Selection Methodology

On September 25, 2009

, the EPA issued a guidance memorandum that provides recommendations to states for making submissions to meet the requirements of CAA section 110(a)(2)(D)(i) for the 2006 24

- hour PM 2.5 standards. See Memorandum from William T. Harnett, Director, Air Quali ty Policy Division, to Regional Air Division Directors, Regions I

- X, “Guidance on SIP Elements Required Under Sections 110(a)(1) and (2) for the 2006 24

- Hour Fine Particle ( PM 2.5 ) National Ambient Air Quality Standards (NAAQS)

, ” September 25, 2009 ( “ 2006 24

- hour PM 2.5 NAAQS Infrastructure Guidance” or “Guidance” ). 16 The Guidance

recommends that each state explain in its SIP submission for section 110(a)(2)(D)(i)(I) SIP

whether or not emissions from sources in the state contribute significantly to nonattai nment or interfere with maintenance of the NAAQS in any other state, and to address any such impacts if they exist

. See Guidance at 3 , 4. The Guidance states as follows:

The state ’ s conclusion must be supported by an adequate technical analysis. Information

to support the state's determination with respect to significant contribution to nonattainment might include, but is not limited to, information concerning emissions in the state, meteorological conditions in the state and the potentially impac ted states, monitored ambient concentrations in the state and the potentially impacted states, the distance to the nearest area that is not attaining the NAAQS in another state, and air quality modeling. The EPA believes that it would be appropriate for st ates to make this assessment by considering the impact of current or future emissions on nearby nonattainment areas, and evaluating the air quality impact and potential mitigation strategies. 17

16 Available at: http://www.epa.gov/ttn/caaa/t1/memoranda/20090925_harnett_pm25_sip _110a12.pdf

17 Guidance at 3.

9T o determine whether the CAA section 110(a)(2)(D)(i)(I) requir ement is satisfied

, the EPA must

determine whether a s tate’s emissions contribute significantly to nonattainment or interfere with

maintenance in downwind areas. If this factual finding is in the negative, then section 110(a)(2)(D)(i)(I) does not require any changes to a state’s SIP. If, however, the evaluation reveals that emissions from sources within the state do contribute significantly to nonattainment or interfere with maintenance in other states, then the state must adopt substantive provisions to mitigate those emissions. The state could a chieve any required reductions through traditional command and control programs, or at its own election, through participation in a cap and trade

program. Consistent with the EPA’ s approach in the 1998 NOx SIP c all , the 2005 CAIR

, and the

2011 Transport Rule, 18 the EPA is evaluating these impacts with respect to specific monitors identified as having nonattainment and/or maintenance problems, which we refer to as “receptors.” 19 The EPA notes that no single piece o f information is by itself dispositive of the issue. Instead, the total weight of all the evidence taken together is used to evaluate significant

contributions to nonattainment in, or interference with maintenance of

, the 2006 24

- hour PM 2.5 NAAQS in anothe r state.

A receptor may be a downwind location that is currently violating the 2006 24

- hour PM 2.5 NAAQS, has violated in the past, is projected to violate in the future, or may have trouble maintaining the NAAQS in the future. Nonattainment and maintenance receptors can be identified using future year modeling, recent ambient data, or both.

If appr opriate future year modeling is not available

, 20 nonattainment and maintenance receptors can be identified using recent ambient air quality monitoring data. For this action, we evaluated

the three most recent consecutive three

- year periods for which comple te, quality

- assured and certified air quality data were available (covering a five

- year period) to calculate “design

values” 21 for those period. We evaluated the design values for monitors located in the following

western states

, which were not included in the modeling domain for the Transport Rule: Arizona, California, Colorado, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington and Wyoming. 22

Because the EPA uses the most recent three

- year design value period for purposes of promulgating air quality designations and redesignations, it is logical to use the most recent 3

- year period to identify “nonattainment” receptors. However, previous violations of the NAAQS

are indicative of an ai r quality problem that may return in the future. The year to year variability of emissions and/or meteorology may cause an area to have trouble maintaining the NAAQS in the future. Therefore, we have identified “maintenance” receptors by examining previo us years

18 See NO

x SIP Call, 63 FR 57371 (October 27, 1998); CAIR, 70 FR 25172 (May 12, 2005); and Transport Rule or

Cross

- State Air Pollution Rule, 76 FR 48208 (August 8, 2011).

19 Air quality designations are not relevant to the methodology for identifying these “receptors.”

20 Available modeling data should be evaluated for the intended purpose. If modeling data is used to establish nonattainment and/or maintenance receptors, it s hould be for an appropriate future year (within the time frame of downwind attainment dates) and model performance should be shown to be acceptable for the upwind and downwind areas being considered.

21 “Design value” means the “calculated concentration ac cording to the applicable appendix of [40 CFR part 50] for the highest site in an attainment or nonattainment area.” 40 CFR 58.1 (definitions).

22 We did not evaluate design values for Alaska or Hawaii.

10of data. This methodology is conceptually similar (although not identical) to the methodology

that the EPA used in the Transport Rule to identify “nonattainment” and “maintenance”

receptors.

In this action w e have applied the following methodology:

Similar to the Transport Rule analysis, we examined ambient data which spanned a five

- year period. This allows examination of year to year variability. T he three most recent consecutive

three

- year design value periods at the time of our ana lysis a re 200 9

- 20 11

, 2010

- 20 12 , and 20 11

- 201 3

. 23

1) N onattainment receptors are those sites that are violating the NAAQS in the most recent

three

- year period (2011

- 2013)

. 24

2) Maintenance receptors are those receptors that show attainment in the most recent three

year design value period ( 2011

- 2013 ) but violated the NAAQS in at least one of the previous two periods ( 2009

- 2011 and/or 2010

- 2012 )

.

Ambient data included the three most recent official design value periods available at the time of the analysis. The official design values are posted by the Office of Air Quality Planning and Standards ( OAQPS ) on the Air Trends website and are available at : http://www.epa.gov/airtrends/values.html

. Also informing this list was the EPA’s AirData

website: http://www.epa.gov/airquality/airdata/

.

The western receptors identified using this methodology and analy zed in this action are shown in

T

able 1 be low. Receptors with 24

- hour PM 2.5 design values above the 24

- hour PM 2.5 standard of 35μg/m 3 for the most recent three

- year period ( 20 11

- 201 3 ) are listed as nonattainment receptors. Receptors with 24

- hour PM 2.5 design values at or below the 24

- hour PM 2.5 standard of 35μg/m 3

for the most recent three

- year period ( 2011

- 2013 )

, but above the standard for at least one of the previous three

- year periods ( 2009

- 2011 or 2010

- 20 12 )

, are listed as maintenance receptors.

To evaluate the potential for significant contribution to nonattainment in other states

, the EPA

first evaluated potential transport to the western states with identified nonattainment receptors : California, Montana, Oregon, and Utah

. 25 To evaluate the potential for interference with

maintenance in other states

, the EPA evaluated potential transport to the western states with

identified maintenance receptors : California

, Montana, and Utah

. 26

23 As noted above, the EPA can consider data from these years for states in the western United States as such data is not impacted by the remanded CAIR.

24 When evaluating recent design values, it is not necessary to average the design values together to create a five

year weighted average. Weighted average da ta is only necessary when projecting modeling data to the future, since modeled projections are generally based on only a single year (or less) of modeled meteorology.

25 As this analysis focuses on interstate transport, EPA did not evaluate the impact of I daho emissions on receptors

within Idaho

. 26 Using the methodology described, no receptors were identified in Arizona, Colorado, Nevada, New Mexico, Washington, and Wyoming.

11Table 1: List of Western Counties with Daily PM 2.5 Nonattainment or Maintenance Receptors

State County 2006 NAAQS 24

- hr

PM 2.5 NAAQS

designated

nonattainment area Site 24

- hr standard ( μg/m 3 )

2009

- 2011 2010

- 2012 2011

- 2013 Receptor Type

California Fresno San Joaquin Valley 060190011 58 NA 59 NA 62 NA Nonattainment

California Fresno San Joaquin Valley 060195001 54 NA 54 NA 58 NA Nonattainment

California Fresno San Joaquin Valley 060195025 48 NA 53 NA 63 NA Nonattainment

California Imperial 060250005 38 NA 32 A 42 NA Nonattainment

California Inyo 060271003 36 NA 33 A 38 NA Nonattainment

California Kern San Joaquin Valley 060290014 62 NA 58 NA 65 NA Nonattainment

California Kern San Joaquin Valley 060290016 55 NA 47 NA 60 NA Nonattainment

California Kings San Joaquin Valley 060310004 46 NA 43 NA 49 NA Nonattainment

California Kings San Joaquin Valley 060311004 57 NV 54 NA 60 NA Nonattainment

California Los Angeles Los Angeles

- South

Coast Air Basin 060370002 36 NA 31 NV 28 A Maintenance

California Madera San Joaquin Valley 060392010 55 NV 51 NA 52 NA Nonattainment

California Merced San Joaquin Valley 060470003 43 NA 41 NA 42 NA Nonattainment

California Merced San Joaquin Valley 060472510 39 NA 40 NA 49 NA Nonattainment

California Riverside Los Angeles

- South

Coast Air Basin 060658005 39 NA 37 NA 38 NA Nonattainment

California Sacramento Sacramento 060670006 35 A 31 A 36 NA Nonattainment

California San Joaquin San Joaquin Valley 060771002 38 NA 36 NA 45 NA Nonattainment

California San Joaquin San Joaquin Valley 060772010 41 NV 38 NA 37 NA Nonattainment

California Stanislaus San Joaquin Valley 060990005 50 NA 44 NA 51 NA Nonattainment

California Stanislaus San Joaquin Valley 060990006 51 NA 49 NA 53 NA Nonattainment

California Tulare San Joaquin Valley 061072002 47 NA 47 NA 56 NA Nonattainment

Idaho Ada 160010010 19 A 27 A 53 NA Nonattainment

Idaho Franklin Logan 160410001 50 NA 47 NA 42 NA Nonattainment

Idaho Lemhi 160590004 38 NA 38 NA 38 NA Nonattainment

Idaho Shoshone 160790017 38 NA 38 NA 40 NA Nonattainment

Montana Lewis and

Clark 300490026 37 NA 33 A 29 A Maintenance

Montana Silver Bow 300930005 39 NA 34 A 39 NA Nonattainment

Oregon Crook 410130100 31 A 31 A 39 NA Nonattainment

Oregon Klamath Klamath Falls 410350004 39 NA 35 A 40 NA Nonattainment

Oregon Lake 410370001 36 NA 34 A 56 NA Nonattainment

Oregon Lane Oakridge 410392013 39 NA 38 NA 40 NA Nonattainment

Utah Box Elder Salt Lake City 490030003 40 NA 37 NA 37 NA Nonattainment

Utah Cache Logan 490050004 42 NA 37 NA 46 NA Nonattainment

Utah Davis Salt Lake City 490110004 40 NA 34 A 35 A Maintenance

Utah Salt Lake Salt Lake City 490350003 50 NA Nonattainment

Utah Salt Lake Salt Lake City 490353006 45 NA 38 NA 41 NA Nonattainment

Utah Salt Lake Salt Lake City 490353010 41 NA 35 A 39 NA Nonattainment

Utah Utah Provo 490490002 35 A 29 A 45 NA Nonattainment

Utah Utah Provo 490494001 41 NA 32 NV 44 NA Nonattainment

Utah Utah Provo 490495008 38 NA 41 NV 42 NV Nonattainment

Utah Utah Provo 490495010 42 NA 35 A 46 NA Nonattainment

12State County 2006 NAAQS 24

- hr

PM 2.5 NAAQS

designated

nonattainment area Site 24

- hr standard ( μg/m 3 )

2009

- 2011 2010

- 2012 2011

- 2013 Receptor Type

Utah Weber Salt Lake City 490570002 41 NA 37 NA 40 NA Nonattainment

Utah Weber Salt Lake City 490571003 37 NA 33 A 35 A Maintenance NA = Not attaining; A = attaining; NV = incomplete data; Blank = monitor not operating

Data sources: AirTrends http://www.epa.gov/airtrends/values.html and AirData http://www.epa.gov/airquality/airdata/

Note: receptors with design values (DV) that would otherwise attain the 24

- hour PM 2.5 standard from 2011 to 2013 but for flagged wildfire exceptional events are excluded from this list (i.e. Ravalli, Montana DV = 27 μg/m 3 ; Missoula, Montana DV = 24 μg/m 3 ; and Jackson, Oregon DV = 34 μg/m 3 ).

II. B

. Factors Considered in Transport Analysis for Nona ttainment and M aintenance

R eceptors

Consistent with the recommendations in the Guidance, the EPA reviewed multiple factors to evaluate the weight of the evidence. The EPA evaluated emission inventory data

, ambient

monitorin g data , and meteorological condi tions within the S tate of Idaho

. Emission inventories used in the Transport Rule modeling analysis provide the following amounts of NOx and SO 2 emissions for Idaho in 2012: 105,888 tons of NOx and 24,326 tons of SO 2

. 27 The monitored

ambient PM 2.5 concentrations for receptors in the State of Idaho are shown in Table 1 above.

In addition, the EPA reviewed PM 2.5 m onitoring data at National Parks and wilderness areas in the west that the EPA believes may be considered representative of western regio nal background

levels of PM 2.5

. As explained in Guidance on the Use of Models and Other Analyses for Demonstrating Attainment of Air Quality Goals for Ozone, PM 2.5 , and Regional Haze , EPA

- 454/B

- 07

- 002, at 98, April 2007, a weight of evidence analysis app ropriately considers such additional models and supplemental analyses. Specifically, w e reviewed five years of data

collected at the IMPROVE 28 monitoring network at specific National Parks and wilderness areas ( c lass I areas ) in Idaho and on the Idaho/Oregon border ( Craters of the Moon National

Monument , Sawtooth Wilderness , Hells Canyon Wilderness , and Starkey ), in Utah (Bryce Canyon National Park

, Canyonlands , Capitol Reef National Park , and Zion )

, in Nevada ( Jarbidge

Wilderness and Great Ba sin National Park )

, at the California

- Oregon border (Crater Lake

National Park , Lava Beds National Monument, and Lassen Volcanic National Park )

, and at the Oregon

- Washington border ( Mount Hood Wilderness and the Columbia River Gorge). 29

27 See “Emissions Inventory Final Rule TSD,” Technical Support Document (TSD) for the final Transport Rule,

Docket ID No. EPA

- HQ

- OAR

- 2009

- 0491, June 28, 2011, at Tables 7

- 1 and 7

- 2.

28 The Interagency Monitoring of Protected Visual Environments (IMPROVE) program is a cooperative measurement effort governed by a steering committee composed of representatives from Federal and regional

- state organizations. The IMPROVE monitoring program was established in 1985 to aid the creation of Federal and State implementation p lans for the protection of visibility in c lass I areas. The objectives of IMPROVE include establishing current aerosol conditions in mandatory class I areas; and identifying chemical species and emission sources responsible for existing man

- made visibi lity impairment. http://vista.cira.colostate.edu/TSS/Results/HazePlanning.aspx

29 See section V. Appendix to this TSD.

13Ambient PM 2.5 monitoring data, as well as c hemical species data ( ammonium nitrate, ammonium sulfate, elemental carbon, organic carbon, sea salt, and soil) is available for each of these monitoring site s

. We provide monitored PM 2.5 d ata from each of the se monitoring sites in

section V. Appendix to this TSD. The data provided is for the 2009

- 2013 period for each day

when measurements occurred at these c lass I monitors

. This provides information about region al background level s of PM 2.5 in the states surrounding Idaho , and as discussed below, provides

information about levels of PM 2.5 at areas located between Idaho and specific ally identified nonattainment and maintenance receptors

. We note that t he chemical composition of the PM 2.5 in these areas is also available on the IMPROVE website

. 30

Most of the elevated levels of PM 2.5 in the western states are measured during the winter months. For example, in 2011 and 2012, each exc e e dance of the 2006 24

- hour PM 2.5 NAAQS in Salt Lake City occurred in either December or January of those years. 31 Monitor values are

accessible on the EPA’s AirData website

. IMPROVE monitoring sites evaluated indicate low background PM 2.5 levels during the winter months for each of the years from 2009 through 2013

. For example, the PM 2.5 values for January and December of 2010 at Bryce Canyon National

Park , Utah are below 3μg/m 3

. See F igure 1 below. While there are variations in the data,

i ncluding peaks during non

- winter months

, we believe the data provided in section V. Appendix

to this TSD generally indicates that PM 2.5 levels in c lass I areas, as monitored by the IMPROVE network, are generally low at the times when areas in the west are typically experiencing

elevated 24

- hour PM 2.5 levels (winter months ).

Figure 1: IMPROVE PM 2.5 Data for Bryce Canyon National Park for the Year 201 0

In addition, the EPA reviewed technical information

, such as meteorological conditions

, topography, distance, and monitored ambient data related to each of the areas with nonattainment

30 http://vista.cira.colostate.edu/TSS/Results/HazePlanning.aspx

31 Monitoring data is accessible on the EPA’s AirData website at http://www.epa.gov/airtrends/values.html 2013 Design Value Report for PM 2.5

.

14and maintenanc e receptors in the potentially impacted western states to evaluate the factors that

cause or contribute to the elevated PM 2.5 levels at these locations

. With respect to the Utah

Idaho, cross

- border Cache Valley airshed, we reviewed controls in the current Idaho SIP to evaluate whether the SIP adequately addresses potential transport from Idaho to Utah f or purposes of CAA section 110(a)(2)(D)(i)(I) for the 2006 24

- hour PM 2.5 NAAQS.

We discuss our evaluation of the factors with respect to each identified nonattainment and

maintenance receptor in the following sections. Please note that some states contain both identified nonattainment receptors and main tenance receptors, specifically: California, Montana,

and Utah. Therefore an evaluation for receptors in these states appear s in both section s III and IV

below.

I II . Transport Assessment for Non a ttainment Receptors

I II

. A. Introduction

Based on the methodology for selecting nonattainment receptors described in section II.A above

, we evaluated nona ttainment receptors in the following western states: California, Montana, Oregon , and Utah

. 32 We have also addressed the nearest eastern receptor evaluated in the Transport Rule modeling domain. 33

I II

. B

. Transport to Western States

III.B.1. California

Eastern California / Inyo County Nonattainment Receptor (Site 060271003)

County Site Name Description

Inyo Keeler This s ite is affected primarily is by crustal sources.

M assive erosion from Owens dry lake; in Owens Valley

.

The EPA identified a single nonattainment receptor in Inyo County, specifically the Keeler monitor, which is located adjacent to the Owen s Lake Bed. (See Figures 2 through 4 below).

The Owens Lake Bed is surrounded by steep terrain.

32 As this analysis focuses on interstate transport, we did not evaluate the impact of Idaho emissions on nonattainment receptors within Idaho.

33 Madison County, Illinois. See “ Technical Support Document (TSD) for the final Transport Rule, Docket ID No.

EPA

- HQ

- O AR

- 2009

- 0491, June 28, 2011

.

15Figure 2 : Keeler D unes 34

T he Owens Valley Planning Area (OVPA) is located in Inyo County in eastern

- central California. It is situated at the south end of the deep, long, narrow Owens Valley with the Sierra Nevada to the west (max imum elev ation 14,495 feet), the Inyo Mountains to the east (max imum

elev ation 14,246 feet ), and the Cos o Range to the south ( max imum elev ation 8,160 f eet). The predominantly dry, alkaline Owens Lake bed is approximately eight miles south of the community of Lone Pine o n U.S. Highway 395, 60 miles north of the city of Ridgecrest, and 35 miles west of Death Valley. The bed of Owens Lake is defined as the area below 3,600 feet above mean sea level (all elevations will be given in feet above mean sea level). The lake bed

e xtends about seventeen miles north and south and ten miles east and west and covers an area of approximately 110 square miles (70,000 acres).

Owens Lake is th e largest single source of PM 10 in the United States. 35 Water was first diverted

from the Owens R iver to the City of Los Angeles in 1913, and by 1926 Owens Lake was dry. Today, the Owens lakebed produces enormous amou nts of windblown dust in exceeda nce of federal air pollution standards for particulate matter. Monitoring and research conducted for

mo re than 20 years, as well as three previous State Implementation Plans (SIPs), has determined

that wind

- blown dust from the dry bed of Owens Lake is the dominant cause of NAAQS

34 http://www.gbuapcd.org/owenslake.htm

35 Ibid.

16violations for PM 10 in the area. 36 Based on the above

- described information abo ut the proximity of this receptor to the large, eroding dry bed of Owens Lake, the distance from Idaho to this receptor (> 300 miles), and the significant intervening terrain, as described above, we believe it

is reasonable to conclude that emissions from Idaho sources do not significantly contribute to

nonattainment of the 2006 24

- hour PM 2.5 NAAQS at this receptor.

Figure 3 : Owens Lake Dust ID Network Map

36 Final 2008 Owens Valley PM 10 P lanning Area Demonstration of Attainment State Implementation Plan, January
28, 2008. http://www.gbuapcd.org/ovpm10sip.htm

17Figure 4 : Owens Lake Contour Map

18Southern California /Riverside County Nonattainment Receptor (Riverside) (Site 060658005)

The high 24

- hour PM 2.5 concentrations in the South Coast Air Basin and at the Riverside nonattainment receptor are mainly due to the secondary formation of smaller particulates

resultin g from mobile, stationary and area source emissions of precursor gases (i.e., NOx, SOx, ammonia ( NH 4 ), and VOC s ) that are converted to PM in the atmosphere. Speciated PM 2.5 data at the Central Los Angeles Site (C E LA) and the Rubi doux site (RIVR) indicate that o rganic c arbon,

a mmonium n itrate, and a mmonium s ulfate constitute the major components at each site . See Figures 5 and 6 below. 24

- hour PM 2.5 design value trends show strong downward trend s at all

sites in the Sou th Coast Basin. 37 See Figur e 7 below.

Figure 5 : Speciated data for the Central Los Angeles Site 38

37 Joe Cassmassi, Scientific, Technical & Modeling Peer Review ( STMPR ) Advisory G roup Meeting, September 22,

2011

. 38 STMPR Item # 5

- 2008 PM 2.5 Air Quality Characterization, January 19, 2012. Bong

- Mann Kim

.

19Figure 6 : Speciated data for Roubidoux site at Riverside 39

39 Ibid.

20Figure 7 : 24

- hour PM 2.5 Design Value Trends

PM 2.5 is essentially a combustion generated pollutant due to the volume of traffic flow and numbers of sources (both point and area) in the region. It is important to note that the areas with the highest concentrations are directly downwind of a n area with major ammonia source s associated with dairies and poultry farming. 40

The South Coast Air Quality 2012 Air Quality Management Plan 41 air quality projections show that the emission control strategy outlined in the plan will result in air quality improvement at each of the nonattainment receptors in the plan , and that each of these sites will attain the

standard in 2014 or sooner

. See Figure 8 below.

40 Final 2012 Air Quality Management Plan (AQMP), Appendix V

– Modeling and Attainment Demonstrations February, 2013.

41 http://www.aqmd.gov/home/library/clean

- air

- plans

21Figure 8 : Maximum 24

- Hour Avera ge PM 2.5 Design Concentrations: 2008 Baseline, 2014

, and 2014 Controlled 42

Based on the air quality trends and projections that indicate that th e above

- referenced emission

strategy will be effective in reducing 24

- hour PM 2.5 levels at this receptor, the distance from

Idaho to this receptor (>500 miles), and the significant intervening terrain including the Sierra Nevada and Cascade Ranges ( see Figu re 9 below)

, we believe it is reasonable to conclude that

emissions from Idaho do not significantly contribute to nonattainment of the 2006 24

- hour PM 2.5 NAAQS at the Riverside receptor.

Central California / Fresno, Kern, Kings, Madera, Merced, San Joaquin , Stanislaus and Tulare

Counties Nonattainment Receptors (Sites: see table 2 below)

Table 2: Central California

– San Joaquin Valley Nonattainment Receptor Sites

County Nonattainment Receptor Sites

Fresno 060190011, 060195001, 060195025

Kern 060290014, 060290016 Kings 060310004, 060311004

Madera 060392010

Merced 060470003, 060472510 San Joaquin 060771002, 060772010

Stanislaus 060990005, 060990006

Tulare 061072002

42 Source: South Coast Air Quality Management District. http://www.aqmd.gov/home /library/clean

- air

- plans

22PM 2.5 levels in the San Joaquin Valley are generally highest in the months of January, Februa ry, November and December. PM 2.5 builds up in episodes of several days or weeks. See Figure 1 0

below. These episodes generally occur during periods with stagnation, cool temperatures, high humidity, and low mixing depths. 43 The peak day co mposition of PM 2.5 at Baker s field is

p rimarily ammonia nitrate (67%) and organic carbon (16%). See Figure 1 1 below.

Figure 9 : Map of California 44

43 Nature of PM 2.5 in the San Joaquin Valley , Karen Magliano, California Air Resources Board, Technical Symposium

. April 27, 2012

. 44 Source: University of Texas. http://www.lib.utexas.edu

23Figure 1 0 : Monthly Average PM 2.5 Concentration in Bakersfield California 45

Figure 1 1 : 2008

– 2010 Peak Day Composition in Bakersfield 46

45 Source: South Coast Air Quality Management District. http://www.aqmd.gov/home/library/clean

- air

- plans

46 Ibid.

24The primary sources of PM 2.5 in the region are diesel engines (nitrate), gasoline engines (nitrate), and agricultural activities (ammonium) which contr ibute regionally. Wood smoke (o rganic

c arbon) and diesel engines ( e lemental c arbon) contribute to the elevated 24

- hour levels of PM 2.5 in urban areas.

Based on the evidence discussed above, that PM 2.5 builds up in episodes of several days or weeks, during periods with stagnation and low mixing depths, the distance fr om Idaho to these receptors (> 300 miles), and the significant intervening terrain, including the Sierra Nevada Range ( see Figure 9 above), we believe it is reasonable to conclude that emissions from Idaho do not significantly contribute to nonattainment o f the 2006 24

- hour PM 2.5 NAAQS at these

receptors.

California/Mexico Border

– Imperial County Nonattainment Receptor (Site 060250005)

L evels of PM 2.5 in Imperial County that exceed the 2006 24

- hour PM 2.5 NAAQS are recorded at
the Calexico

– Ethel Street monitoring site, which is located near the Mexican Border ( see Figure 1 3 below). The elevated levels of PM 2.5 occur primarily in the wintertime, and seven of

the nine values above the level of 35 μg/m 3 in the years 200 8

- 2010 occur in December or January ( See Table 3 below).

Table 3: Calexico

- Ethel Street: Dates of PM 2.5 Values Above 35 μg/m 3 (2006

- 2010)

Year Date s 2008 January 4, and December 22, 25

2009 September 4, and December 12, 21, 24

2010 June 28, and December 4

T he levels of PM 2.5 measured at the Brawley and El Centro monitoring sites are always lower

– usually much lower

– than those measured at the Calexico Ethel Street monitor on days when the

PM 2.5 levels at the Calexico Ethel Street monitor exceed 35 μg/m 3 . S ee Figure s 1 3 and 1 4 b elow. Because these nearby monitors do not show similar increases in monitored values, it appears that

t he elevated PM 2.5 is being significantly influenced by a source near the California/Mexico

Border.

Based on the above

- descr ibed information, distance from Idaho to this California receptor (> 600 miles), and significant intervening topography , including the Sierra Nevada Range (see Figure 9 above) , we believe it is reasonable to conclude that emissions from Idaho do not significantly

contribute to nonattainment of the 24

- hour PM 2.5 standard at this receptor.

25Figure 13 : PM 2.5 Monitoring Sites in Imperial County California

26Figure 14 : PM 2.5 levels (μg/m 3 ) at Imperial PM 2.5 Monitoring Sites

, 2006

- 2010, for days of

elevated 24

- hour PM 2.5

Northern California

– Plumas County Nonattainment Receptor (Site 0600631006)

County Site Description

Plumas Quincy This receptor violated the 2006 24

- hour PM 2.5 NAAQS in the most recent design value period (2011

- 2013) but was in attainment of the

24

- hour PM 2.5 NAAQS in the three previous design value periods.

The EPA identified a single nonattainment receptor in Northern California

– the Plumas County receptor located in Quincy. While this receptor is located in an area that is designated attainment

for the 2006 24

- hour PM 2.5 NAAQS, portions of Plumas County are being considered in the designations process for the 2012 annual PM 2.5 NAAQS. 47 We note that we are not evaluating

47 EPA Technical Support Document for California for the 2012 Primary Annual PM 2 .5 NAAQS. http://www.epa.gov/pmdesignations/2012standards/eparesp/09_CA_120TSD_20140818.pdf 0 10 20 30 40 50 60 70 Calexico -Ethel

El Centro

Brawley

27interstate transport requirements for the 2012 annual PM 2.5 NAAQS in this action, however, we believe that the information developed as part of the designations process for the 2012 annual

PM 2.5 NAAQS is informative for our evaluation of this receptor for purposes of interstate transport requirements for the 2006 24

- hour PM 2.5 NAAQS. 48

A letter from the Northern Sierra Air Quality Management District, dated June 18, 2014, cites wood burning for residential heating in wood stoves and fireplaces, open burn piles for yar d waste disposal, and prescribed burning in nearby federal lands performed by the U.S. Forest Service and a railroad switching yard as the sources affecting PM 2.5 concentrations in Portola,

located in Plumas County, 32 miles from Quincy

. 49 El evated PM 2.5 in the winter months in

Portola is generally considered related to emissions from residential wood burning. The letter

cite d the diurnal pattern of PM 2.5 concentrations that peak around the two times people use their

wood stoves most: from 5:00 pm to 12:00 am, and from 5:00 am to 8:00 am. With respect to the Quincy receptor, the Northern Sierra Air Quality Management District indicated that similar diurnal patterns are found in Quincy, but not to the same degree. The letter stated that “emissions in Quincy are also mainly from wood burning appliances (as supported by diurnal PM 2.5 concentration patterns), although Sierra Pacific Industries maintains a biomass

- fired cogeneration facility in Quincy that emitted an 2010

- 2012 average of 44 tons per year of tota l particulate matter.” 50

The population of Plumas County is 19,940. 51 The county lies in the northern Sierra Nevada Mountains near the southern border of the Cascade Range

. The topography of Plumas County is highly variable, including mountain peaks (> 7,00 0 ft

. ) and valleys with extreme slop es and

differences in altitude. 52 This topography affects and directs airflow, causing shallow vertical mixing, and creating areas of high pollutant concentrations by hindering dispersion. 53 Quincy is located in a small and isolated mountain valley at approximately 5000 feet elevation. 54
Prevailing winds in Quincy are from the west, and much of the time there is no measureable wind in Quincy, as indicated by wind roses developed by Northern Si erra Air Quality Management District. 55

Based on the nature of the PM 2.5 probl em in general at this receptor as described above, the distance from Idaho to this receptor (approximately 250 miles), low background levels of PM 2.5 at the time when these excee dances generally occur, 56 and s ignificant intervening terrain as

48 EPA Technical Support Document for California for the 2012 Pri mary Annual PM 2.5 NAAQS. http://www.epa.gov/pmdesignations/2012standards/eparesp/09_CA_120TSD_20140818.pdf

49 2012 Northern Sierra Air Quality Management Dist rict letter dated June 18, 2014

. http://www.epa.gov/pmdesignations/2012standards/rec/r9carec2.pdf

50 Ibid at page 4.

51 2010 Census.

52 EPA Technical Support Document for Califor nia for the 2012 Primary Annual PM 2.5 NAAQS. http://www.epa.gov/pmdesignations/2012standards/eparesp/09_CA_120TSD_20140818.pdf

53 2012 Northern Sierra Air Quality Management District letter dated June 18, 2014

. http://www.epa.gov/pmdesignations/2012standards/rec/r9carec2.pdf

54 Ibid. at page 2.

55 Ibid. at Attachment 6, page 13.

56 IMPROVE monitoring data at Jarbidge Wilderness Area, NV, and Lassen Volcanic National Park , CA

. See

section V. Appendix to this TSD.

28described above , we believe it is reasonable to conclude that emissions from Idaho do not contribute significantly to nonattainment of the 24

- hour PM 2.5 standard at this receptor.

Figure 15 : Topographical Map of Plumas County 57

III.B.2 . Montana

Silver Bow County Nonattainment Receptor (Butte) (Site 300930005)

Elevated levels of PM 2.5 in the Butte area also occur primarily in the winter months. 58 The Butte area is topographically prone to wintertime temperature inversions, as it is situated in a mountain valley. The mountains of the Lewis Range and the Bitteroot Range , part of the Rocky Mountains, are situated to the west of Butte, between Idaho and this receptor. See Figure 1 6

57 EPA Technical Support Document for California for the 2012 Primary Annual PM 2.5 NAAQS. http://www.epa.gov/pmdesignations/2012standards/eparesp/09_CA_120TSD_20140818.pdf

58 In 2009 and 2010, the only recent years in which the Butte maintenance recep tor violated the 2006 PM 2.5 NAAQS, each exceedance of the NAAQS occurred in either December or January. Monitor values are accessible on EPA’s AirData website, http://www.epa.gov/airquality/airdata/

.

29below. The tallest peaks in the Bitteroot Range reach 7,000 to 11,000 feet. Speciation data indicates that emissions from wood smoke are the primary contributor to exceedances of the

PM 2.5 standard in Butte. 59 These factors indicate that high levels of PM 2.5 in Butte build as emissions become trapped in the mountain valley du ring wintertime inversions. 60

Given the characteristics of the elevated PM 2.5 levels at this receptor, air quality data indicating that regional background levels of PM 2.5 are generally low d uring the time periods of elevated

PM 2.5 at this receptor

, 61 and the intervening topography be tween Idaho and this receptor, as described above

, we believe it is reasonable to conclude that emissions from Idaho sources do not contribute significantly to non attainment of the 2006 24

- hour PM 2.5 NAAQS at this receptor.

Figure 1 6 : Map of Montana 62

I II .B.3 . Oregon

Crook County Nonattainment Receptor (Site 410130100)

59 Ward, T., Lange, T

. , “The impact of wood smoke on ambient PM 2.5 in northern Rocky Mountain valley communities.” Environmental Pollution 158 (2010) 723

– 729

. 60 Ibid.

61 Craters of the Moon, ID, Sawtooth National Forest, ID, Sula Peak Wilderness Area, MT, G ate of the Mountains Wilderness Area, MT. See section V. Appendix to this TSD and http://vista.cira.colostate.edu/TSS/Results/HazePlanning.aspx

62 Source: University of Texas. http://www.lib.utexas.edu

30Crook County is located in central Oregon and the city of Prineville is the county seat

- population 9,253. 63 The Cascade Range borders on the west of the region, with high desert to the

east and the Ochoco Mountains to the northeast. Prineville is marked with a blue triangle near the center of the state as depicted in Figure 1 7 below.

Fig ure 1 7 : Map of Oregon

– Prineville, Klamath Falls, Lakeview 64

Within Central Oregon, Crook County has a high rate of residential wood burning. 65 PM 2.5 speciation data is not available for the Prineville receptor, but daily mean PM 2.5 concentration
time series between 2009 and 2013 show that the highest values have typically occurred in the
winter months of December and January, indicating an association with residential wood burning
and wintertime inversion meteorology. See Figure 18 below.

63 2010 Census.

64 Source: www.lib.utexas.edu

65 See Oregon 2005 Residential Wood Combustion Emission Inventory , Oregon Department of Environmental Quality.

31Figur e 18 : Prineville, Oregon Daily Mean PM 2.5 Concentrations

In addition, PM 2.5 levels at IMPROVE monitors in between Idaho and this receptor are general ly low during the winter months ( < 5 μg/m 3 ) when exceedances at the Prineville receptor have typically occurred. 66 The significant topography between Idaho and this receptor includes the

Ochoco Mountains and other parts of the Blue Mountains, the Wallowa Mountains and the Steen

Mountains.

Based on the nature of the PM 2.5 problems at this receptor as described above , the distance of this receptor from Idaho (approximately 200 miles), low background levels at IMPROVE monitors in the class I areas between this receptor and Idaho when wintertime inversion

- related exceedances of the NAAQS gener ally occur, 67 and the significant terrain between Idaho and this receptor as

described above , we believe it is reasonable to conclude that emissions from Idaho do not contribute significantly to nonattainment of the 2006 24

- hour PM 2.5 NAAQS at this recepto r.

66 IMPROVE monitoring network at Hells Canyon, ID and Starkey, OR. See section V. Appendix to this TSD and http://vista.cira.colostate.edu/TSS/Results/HazePlanning.aspx

67 Ibid.

32Klamath County Nonattainment Receptor (Klamath Falls) (Site 410350004)

A portion of Klamath County is designated nonattainment for the 2006 PM 2.5 NAAQS. 68
Klamath Falls is a relatively small urban community located in and supporting a vast rura l area

in south

- central Oregon, near the California border. See Figure 1 7 above

. The community lies in a valley at the northern end of the Klamath basin, a broad valley surrounded by mountains. Klamath Falls is at an elevation of approximately 4500 ft. ab ove mean sea level (MSL). Surrounding mountains rise to 5000

- 6000 ft. MSL. A 2005 emission inventory conducted by Oregon shows that wood stove emissions are the most significant source of emissions. 69

Additional air quality monitoring data provide suppo rting evidence that residential wood

combu stion emissions are a primary contributor to exceedance days. 70 Data shows exceedances occur during winter months, at a time when woodstoves are contributing to smoke in the area.

Exceedances occurred from Decembe r through January, corresponding directly with the winter wood heating season and indicate the exceed ances are a seasonal occurrence, except flagged

wildfire events. 71

Speciation data analysis indicates most of the PM 2.5 comes from elemental and organic carbon, typical indicators of combustion activities such as wood burning. 72 Meteorological data from Klamath Falls show that low wind speeds dominate during violating days, and the Klamath Falls area experiences frequent winter

- time nocturnal inversions, w hen PM pollution can build up over

time. Diurnal concentrations of PM 2.5 are observed by hourly light scatter data that correspond closely with night

- time use of woodstoves. Night

- time inversions coupled with low wind speeds strongly suggest that polluti on in the Klamath Falls area builds when trapped by winter, night

time inversions. EPA R10 factor analysis modeling identified the following 5 categories of

aerosol contributing to PM 2.5 : Nitrate Rich, Organic Pyrolysis Rich, Soil, Sulfate Rich, Wood

Smo ke. EPA R10’s analysis of average factor contributions on winter season days with elevated

PM 2.5 shows Wood Smoke dominating at 72%.

Based on the above

- described information, distance from Idaho to this receptor (> 200 miles), low background levels at IM PROVE monitors in class I areas near this receptor at the time of

elevated PM 2.5 , 73 and significant intervening terrain (as discussed above), we believe it is reasonable to conclude that Idaho emissions do not significantly contribute to nonattainment of

th e 2006 24

- hour PM 2.5 NAAQS at this receptor.

Lake County Nonattainment Receptor (Lakeview) (Site 410370001)

68 Technical Support Document, Oregon Area Designations for the 24

- Hour Fine Particle National Ambient Air Quality Standards http://www.epa.gov/pmdesignations/2006standards/final/TSD/tsd_4.0_4.10_4.10.3_r10_OR.pdf

69 Ibid.

70 Ibid.

71 Ibid.

72 Ibid.

73 Crater Lake, OR, Lava Beds National Monument, CA, Starkey, ID, Jarbidge Wilderness Area, NV. See V. Appendix to this TSD and http://vista.cira.colostate.edu/TSS/Results/HazePlan ning.aspx

33As seen in Figure 1 7 above, Lakeview, Oregon is located to the east of Klamath Falls, and is the county seat of Lake County

, population 2,294. 74 Lakeview is located in the Goose Lake Valley at the foot of the Warner Mountains to the east. Lakeview is on the edge of the high desert country of southeastern Oregon. At an elevation of 4,800 feet (1,500 m), Lakeview is one of the highest cities in Oreg on

. 75 The significant topography between Idaho and this receptor includes

the Warner Mountains, Blue Mountains, Wallowa Mountains and Steen Mountains.

EPA R10 factor analysis modeling identified the following 7 categories of aerosol contributing

to PM 2. 5 : Nitrate Rich, Organic Pyrolysis Rich, Potassium Rich, Soil, Sulfate Rich, Urban Unidentified, and Wood Smoke. EPA R10’s analysis of average factor contributions on winter season days with elevated PM 2.5 shows Wood Smoke dominating at 67%.

Based on the nature of the PM 2.5 problem in Lakeview described above, low background levels at IMPROVE monitors in class I areas near this receptor during the winter months when exceedances typically occur

, 76 distance from Idaho to this receptor (approximately 170 m iles),

and s ignificant intervening terrain as described above , we believe it is reasonable to conclude that Idaho emissions do not significantly contribute to nonattainment of the 2006 24

- hour PM 2.5 NAAQS at this receptor.

Lane County Nonattainment Recept or ( Oakridge) ( Site 410392013)

A portion of Lane County is designated nonattainment for the 2006 PM 2.5 NAAQS (Oakridge

NAA )

. 77 Elevated levels at the Oakridge nonattainment receptor generally occur during winter stagnation events and t he technical analysis developed during the designations process by the State of Oregon and the EPA points to residential home heating using wood burning appliances

, as being the main contributor to fine particle pollution in the area. 78 The EPA R egion 10 fact or analysis modeling identified the following seven categories of aerosol contributing to PM 2.5 : Gasoline Vehicles, Organic Pyrolysis Rich, Sea Salt, Soil, Sulfate Rich, Urban Unidentif i ed, and

Wood Smoke. EPA R egion 10’s analysis of average factor contributions on winter season days

with elevated PM 2.5 shows Wood Smoke dominating at 72%.

Oakridge, Oregon is a small, isolated mountain community 35

- 40 miles east of Eugene

, Oregon, surrounded by national forest. It is located in Lane County, which st retches from the Pacific

Ocean to the mountains of the Cascade R ange. Vast areas of Lane County are forested mountains of the Coast Range and Cascade Range. 79 Oakridge lies in an alluvial plain in the foothills at the

southern end of the Willamette River va lley and is 28 miles west of Willamette Pass, the summit of the Cascade Mountain Range (approximately 5000 feet in elevation )

. Elevation in the area ranges fro m 1100 feet at the lower (west) end to 1600 feet with areas of densest population

74 2010 Census.

75 Oregon topographic map , United States Geological Survey, United States Department of Interior, Reston,

V irginia; displayed via ACME mapper, www.acme.com , 19 July 2014.

76 Crater Lake, OR, Lava Beds National Monument, CA, Starkey, ID, Jarbidge Wilderness Area, NV. See V. Appendix to this TSD and http://vista.cira.colostate.edu/TSS/Results/HazePlanning.aspx

77 2006 24

- Hour PM 2.5 NAAQS Designations (November 13, 2009 ; 74 FR 58688 )

. 78 Technical Support Document, Oregon Area Designations for the 24

- Hour Fine Particle National Ambient Air Quality Standards http://www.epa.gov/pmdesignations/2006standards/final/TSD /tsd_4.0_4.10_4.10.3_r10_OR.pdf

79 Ibid.

34situated b etwe en 1100 feet and 1200 feet. 80 Mountains rise on the north and south sides to 1700 feet and 1600 feet, respectively. 81 T here is significant topography between Idaho and Oakridge, Oregon including the Cascade Range , Wallow a Mountains and Steen Mountains as d epicted in Figure 17 above. This terrain reaches up to 5000 feet at the summit of Willamette Pass

.

Based on th e above information, the distance of this receptor from Idaho (> 250 miles), low background levels at IMPROVE monitors in the c lass I areas between this receptor and Idaho 82

when wintertime inversion

- related exceedances of the NAAQS generally occur, and the significant terrain between Idaho and this receptor as described above

, we believe it is reasonable

to conclude that emissions from Idaho d o not contribute significantly to nonattainment of the

2006 24

- hour PM 2.5 NAAQS at this receptor.

I II

. B

. 4

. Utah

Utah County Nonattainment Receptor s (Provo ) (Site s 490490002, 490494001, 490495008

, 490495008 )

A large portion of Utah County is designated as the Provo 2006 24

- hour PM 2.5 nonattainment

area ( Provo NAA)

. 83 The Provo nonattainment receptor s identified are situated in the Utah Valley. Like the other low

- lying valleys just west of the Wasatch Front, the topography of the Utah Valley makes it prone to temperature inversions. See Figure 18 below. The Wasatch Mountain Range rises from the valley floor to approximately 7,000 to over 9,000 ft. MSL and

defines the eastern boundaries of both the Salt Lake Valle y to the north and the Utah Valley to the south. These valleys are bound on their respective western sides by the Oquirrh Mountains which also have heights of 7,000 ft. MSL to well over 9,000 ft. MSL. North of Salt Lake County, the Wasatch Mountain Range c ontinues to act as a barrier to the east, while the Great Salt Lake serves as the western boundary. 84

Elevated levels of PM 2.5 at these receptor s occur primarily in the winter months. 85 The levels of

elevated PM 2.5 at these receptor s are driven by inversio n meteorology which traps pollutants and leads to exceedances, as noted in the discussion of these receptors below. 86 During the winter months, levels of PM 2.5 at background monitoring sites located north and west of this receptor 87

80 Ibid.

81 Ibid.

82 IMPROVE monitoring network at Hells Canyon, ID and Starkey, OR. See section V. Appendix to this TSD and http://vista.cira.colostate.edu/TSS/Results/HazePlanning.aspx

83 2006 24

- Hour PM 2.5 NAAQS Designations (74 FR 58688, November 13, 2009), Technical Support Document,

December 2008. http://www.epa.gov/pmdesignations/2006standards/final/TSD/tsd_4.0_4.8_4.8.2_r08_UT.pdf

. 84 Ibid. at page 48.

85 For example, in 2011 and 2012, each exceedanc e of the 2006 PM 2.5 NAAQS in Salt Lake City occurred in either December or January of those years. Monitor values are accessible on EPA’s AirData website, http://www.epa.gov/airquality/airdata/

. 86 2006 24

- Hour PM 2.5 NAAQS Designations (74 FR 58688, November 13, 2009), Technical Support Document,

December 2008. http://www.epa.gov/pmdesignations/2006standards/final/TSD/tsd_4.0_4.8_4.8.2_r08_UT.pdf . At page 48.

87 IMPROVE monitoring network at Craters of the Moon, ID, Sawtooth National Forest , ID and Jarbidge

Wilderness Area , NV. See section V. Appendix to this TSD and http://vista.cira.colostate.edu/TSS/Results/HazePlanning.aspx

35are very low, generally below 3μg/m 3

, and the vast majority of the PM 2.5 in the urban area is generated within the area and trapped during winter inversion meteorology

.

Figure 18 : Monitoring Network with Counties and Topography 88

88 Source: Utah Department of Environmental Quality. 2006 24

- Hour PM 2.5 NAAQS Designations (74 FR 58688,

Novemb er 13, 2009), Technical Support Document, December 2008. http://www.epa.gov/pmdesignations/2006standards/final/TSD/tsd_4.0_4.8_4.8.2_r08_UT.pdf . at page 19.

36During inversions, the Provo NAA features stagnant air masses and calm to light winds. As the

airshed is essentially capped, PM 2.5 is formed in

- situ (and trapped) via fresh emission sources and secondary chemistry. Transport of air masses between Salt Lake City and Provo receptors can occur during inversions, as there is a 4.75

- mile gap in the mountains separating these airsheds

which is below the approximate average inversion height for these areas. 89

Speciation data from wintertime PM 2.5 exceedance days from 2004

- 2006 showed the average composit ion of PM 2.5 in Provo is 71% ammonium nitrate, with 21% carbon and organic compounds, 8% ammonium sulfate, and 2% crustal. Several factors, including significant

amounts of emissions from mobile, point and area sources

, contribute to primary and secondari ly

formed PM 2.5 that violate the 2006 24

- hour PM 2.5 NAAQS during stable weather events associated with strong inversions. 90

B ased on the meteorology, topography and characteristics of the PM 2.5 levels during time periods

when the 24

- hour PM 2.5 standard is exceeded as described above, as well as the low levels of background PM 2.5 during these time periods at IMPROVE monitors in the class I areas near these

receptor s and Idaho 91 it is reasonable to conclude that emissions from Idaho do not significantly

contribute to nonattainment of the 2006 24

- hour PM 2.5 NAAQS at t hese receptor s

.

Box Elder, Salt Lake and Weber Counties Nonattainment Receptors (Greater Salt Lake City ) (Sites 490030003, 490350003, 490353006, 490353010, 490570002)

All of Salt Lake c ounty an d portions of Box Elder and Weber c ounties are designated as part of the Salt Lake City (SLC) 2006 24

- hour PM 2.5 nonattainment area (NAA)

. 92 The EPA identified nonattainment receptors in each of the three counties. The SLC NAA and these nonattainment

receptors are situated in a valley bordered on the w est by the Stansbury Mountains, 93
Promontory Mountains and Great Salt Lake, and on the e ast by the Wasatch Front. Like the

other low

- lying valleys just west of the Wasatch Front, the topography of the Sal t Lake valley makes it prone to temperature inversions. See Figure 18 above.

A western topographic airshed barrier for eastern Box Elder County involves the Promontory Mountains and North Promontory Mountains. 94 The Promontory Mountains are located

approx imately 24 miles west of both Brigham City and Ogden and show approximate altitudes of

89 Ibid. at page 41.

90 Ibid. at page 34.

91 IMPROVE monitoring network at Craters of the Moon, ID, Sawtooth Wilderness , ID and Jarbidge Wilderness

Area , NV. See section V. Appendix to this TSD and http://vista.cira.colostate.edu/TSS/Results/HazePlanning.aspx

92 2006 24

- Hour PM 2.5 NAAQS Designations (74 FR 58688, November 13, 2009), Technical Support Document,

December 2008. http://www.epa.gov/pmdesignations/2006standards/final/TSD/tsd_4.0_4.8_4.8.2_r08_UT.pdf . At page 25.

93 The Quqirrh Mountains lie between the Wasatch Front and the Stansbury Mountains. However, EPA determined that some area located west of the Quqirrh Mountains should still be considered part of the SLC nonattainment area.

94 2006 24

- Hour PM 2.5 NAAQS Design ations (74 FR 58688, November 13, 2009), Technical Support Document,

December 2008. http://www.epa.gov/pmdesignations/2006standards/final/TSD/tsd_4.0_4.8 _4.8.2_r08_UT.pdf . At page 48.

375,600 ft. (MSL) in the south (extending into the Great Salt Lake), areas of over 6,000 ft. (MSL) in the middle, and 5,000 ft. to the North where they meet the southern e nd of the North Promontory Mountains. The southern end of the North Promontory Mountains are approximately 5,000 ft. (MSL) and are also approximately 5,000 ft. (MSL) to the north (northwest of Howell, UT.) 95

The Stansbury Mountains are located approximatel y 17 miles west of Tooele City (approximately 43 miles southwest of Salt Lake City) and show approximate altitudes of 8,300 ft. (MSL) in the south, areas 7,000 ft. (MSL) to over 9,500 ft. (MSL) in the middle, and 5,000 ft. (MSL) to the North where they mee t the Great Salt Lake. Also, an impediment to airflow in this

area includes the South Mountain ridge located at the southern end of the Tooele Valley. This ridge essentially connects the Stansbury Mountains to the Oquirrh Mountains and has a maximum height of approximately 6,500 ft. (MSL). Therefor e, it is likely that Salt Lake County is contributing to Utah C ounty’s high concentration PM 2.5 violations and that U tah C ount y is contributing to Salt Lake C ounty’s high concentration PM 2.5 violations. 96

During i nversions, the SLC NAA becomes a closed airshed (save for potential transport between the Salt Lake City and Provo NAAs) featuring stagnant air masses and light winds which typically oscillate back and forth within the airshed. As the airshed is essentiall y capped during inversions, PM 2.5 is formed in

- situ (and trapped) via fresh emission sources and secondary chemistry. 97 Speciation data from wintertime PM 2.5 exceedance days from 2004

- 2006 showed the average composition of PM 2.5 in Salt Lake City is 58% amm onium nitrate, 31% carbon and organic compounds, 8% ammonium sulfate, and 2% crustal. Several factors, including significant amounts of emissions from mobile, point and area sources

, contribute to primary and secondarily formed PM 2.5 that violate the 2006 24

- hour PM 2.5 standard during stable weather events associated with strong inversions. 98

B ased on the meteorology, topography and characteristics of the PM 2.5 levels during time periods

when the 24

- hour PM 2.5 standard is exceeded, as described above, as well as the low levels of background PM 2.5 during these time periods at IMPROVE monito rs at class I areas near this receptor and Idaho 99 it is reasonable to conclude that emissions from Idaho do not significantly

contribute to nonattainment of the 2006 24

- h our PM 2.5 NAAQS at t hese receptor s

.

Cache County / Franklin County Nonattainment Receptor (Logan) (Site 490050004 )

Portions of Cache County, Utah and Franklin County , Idaho make up the Cache Valley, a mountain valley straddling the Utah

- Idaho border. Portions of these two counties are also

95 Ibid. at page 48.

96 Ibid. at page 49.

97 Ibid. at page 34.

98 Ibid. at page 53.

99 IMPROVE monitoring network at Craters of the Moon, ID, Sawtooth Wilderness Area , ID and Jarbidge

Wilderness Area , NV. See section V. Appendix to this TSD and http://vista.cira.colostate.edu/TSS/Results/HazePlanning.aspx

38designated as part of the Logan UT

- ID 2006 24

- hour PM 2.5 , cross

- state nonattainment area ( Cache Valley NAA)

. 100 See Figure 19 below.

Figure 19 : Location map showing the Cache Valley and the boundaries for Franklin County, Idaho, and Cache County, Utah. 101

100 2006 24

- Hour PM 2.5 NAAQS Designations (74 FR 58688, November 13, 2009), Technical Support Document

, December 2008. http://www.epa.gov/pmdesignations/2006standards/final/TSD/tsd_4.0_4.8_4.8.2_r08_UT.pdf . At page 2.

101 Source Utah Department of Environme ntal Quality.

39Limited chemical speciation data indicates the 24

- hour PM 2.5 problem is dominated by

ammonium nitrate aerosol similar to nonattainment areas along the Wasatch F ront in and near

Salt L ake City. 102 The chemical speciation monitor in Bountiful is closest to the Cache Valley and is considered broadly representative of conditions in the Cache Valley. 103 The ridge dominated synoptic meteorology during PM 2.5 cold pool episodes features weak transport winds and near calm surface winds. As a result, transport of PM 2.5 and precursors from the rural regions at the domain periphery is limited . In addition, most of the observed Wasatch Front and Cache Valley PM 2.5 is formed in

- situ (and trapped) via fresh emission sources and secondary chemistry. 104

Residential heating emissions from woodstoves, emissions from agricultural activities, and

mobile source emissions contribute to primary and secondarily formed PM 2. 5 that violate the 24

- hour standard during stable weather events associated wi th extremely strong inversions. These emissions and the related effects are limited to the Cache Valley, as they are trapped there due to temperature inversions, low wind, and si gnificant topography. 105

The most prominent topographical features impacting the Cache Valley as a whole include : (1) the eastern boundary of the v alley which is composed of the Wasatch

- Cache National Forest, the Bear River Mountain Range, and Monte Cristo Mountain Range, and (2) the western boundary which is composed of the northern section of the Wasatch Mountain Range and the Wellsville Mountain Range. The mountains to the east rise to approximately 8,300 feet MSL and to the

west the mountains rise to approximately 9,900 feet MSL. However, the valley floor only ranges in altitude from approximately 4,500 feet MSL to 5,200 feet MSL from south to north respectively. 106

The Wellsville Mountains, Bear River Mountains, and northern Wasatch mountains converge in southern Cache County , Utah to form a topographical barrier between the Cache Valley and other adjacent Utah counties such as Box Elder and Weber. As with the southern area of the Cache Valley, the mountain ranges of the northern area of the Cache Vall ey, bordering the eastern and western portions of Franklin County, effectively meteorologically isolate Franklin County from Bannock, Bear Lake, Caribou, and Oneida Counties in Idaho. 107

EPA Region 10 factor analysis modeling identified 11 categories of aer osol contributing to

elevated wintertime 24

- hour PM 2.5 levels at the Bountiful monitoring site including nitrate rich (56%), ammonium chloride (15%), wood smoke (10%), organic pyrolysis rich (6%), sulfate rich (5%) and smaller contributions by other identi fi ed factors (gasoline vehicles, two soil factors, fireworks, iron rich, and urban unidentified).

102 2006 24

- Hour PM 2.5 NAAQS Designations (74 FR 58688, November 13, 2009), Technical Support Document,

December 2008. http://www.epa.gov/pmd esignations/2006standards/final/TSD/tsd_4.0_4.8_4.8.2_r08_UT.pdf . At page 9.

103 Ibid. at page 14

- 15.

104 Ibid. at page 14

- 15.

105 Ibid. at page 17

- 18.

106 Ibid. at page 17

- 18.

107 Ibid. at page 7.

40Based on the Idaho 2010 Interstate Transport submittal and our analysis of TSDs developed for designations purposes as described above

, we believe it is reasonable to conclude that Idaho sources do not significantly contribute to nonattainment in Utah , with the possible exception of within the Cache Valley

. However, b ased on the information available at this time, we are unable to conclude whether e missions from sources o n the Idaho side of the Cache Valley

contribute significantly to nonattainment on the Utah side of the Cache Valley for purposes of CAA section 110(a)(2)(D)(i)(I)

. Therefore, we are supplementing our evaluation with a review

of cont rol measures approved into Idaho SIP that address PM 2.5 emissions from sources in the Cache Valley, in addition to technical data on the composition of sources of PM 2.5 in the Cache Valley

.

In December of 2012, Idaho submitt ed its attainment SIP for the Franklin County side of the Logan U T

- I D 2006 24

- hour PM 2.5 NAA under subpart 1

, part D , title I of the CAA. 108 This

submittal contained technical data on sources of PM 2.5 in the Cache Valley, and included controls

for residential wood smoke emissions and road sanding agreements to address direct PM 2.5 emissions in Franklin County

. We note that we are not evaluating the December 2012 submittal with respect to CAA, title I part D requirements. The requirements of part D will be addressed in a separate acti on. We are providing this technical analysis in order to evaluate whether Idaho has met its obligation to address CAA section 110(a)(2)(D)(i)(I) requirements with respect to the

2006 24

- hour PM 2.5 NAAQS in all of Idaho, including within the Cache Valley. Below we

describe the relevant information from the December 2012 submittal.

The December 2012 submittal stated that t he Idaho side of the Cache Valley (portion of Franklin County) is sparsely populated and the majority of the population live in small tow ns. The two largest Idaho towns in the Franklin County portion of the Cache Valley are Preston, with a 2006 population of 5,089, and Franklin, with 672 residents. Franklin County contains no major point

sources of PM 2.5 or PM 2.5 precursors, defined in the submittal as a facility with the potential to

emit annual emissions of 100 tons or more. Sources of direct PM 2.5 and precursors (SO 2 , NO X , VOCs, ammonia) on the Idaho side of the Cache Valley include emissions from mobile vehicles, agriculture and livestock, re

- entrained road dust, and residential wood combustion

. F igures 2 0

– 2 4 below show PM 2.5 and precursor emissions sorted by source type and county (Franklin County, Idaho; Cache County, Utah) within the Cache Valley. 109

108 Cache Valley Idaho PM 2.5 Nonattainment Area State Implementation Plan, State of Idaho Department of Environmental Quality, December 2012.

109 Ibid. at page 24

- 26.

41Figure 2 0 : Nitrogen ox ide emission totals sorted by source type and county. 110

110 Source: Idaho Department of Environmental Quality.

42Figure 2 1 : Volatile organic compound emission totals sorted by source type and county. 111

111 Source: Idaho Department of Environmental Quality.

43Figure 2 2 : Ammonia emission totals sorted by source type and county. 112

112 Source: Ida ho Department of Environmental Quality.

44Figure 2 3 : Sulfur dioxide emission totals sorted by source type and county. 113

113 Source: Idaho Department of Environmental Quality.

45Figure 2 4 : PM 2.5 emission totals sorted by source type and county. 114

Because secondary chemistry is an important driver of elevated PM 2.5 in the Cache Valley, Idaho evaluated potential controls on precursor emissions that lead to the formation of PM 2.5 in the atmosphere

. 115 The submittal provided technical support indicating that ammonium nitrate formation is the predominant process that leads to high PM 2.5 concentrations in the Cache Valley during winter inversions. 116 The Cache Valley has been determined to be amm onia rich by a factor of 2 to 1, and it may be considered more efficient to seek to control the limiting reagent (NOx) with respect to the secondary formation of ammonium nitrate. 117 Modeling s ensitivity runs conducted by Utah and Idaho indicate that significant reductions in the ammonia emissions inventories have little to no effect on predicted PM 2.5 concentrations in the Cache Valley airshed

. 118

NO x emissions, generally from combustion f rom heating and mobile sources, contribute to the

PM 2.5 problem in the Cache Valley through the formation of ammonium nitrate secondary

aerosol. See Figure 2 0 above. The Idaho side of the Cache Valley is sparsely populated, as described above, and Idaho asse rted in their December 2012, submittal that additional controls

114 Source: Idaho Department of Environmental Quality.

115 Cache Valley Idaho PM 2.5 Nonattainment Area State Implementation Plan, State of Idaho Department of

Environm ental Quality, December 2012. At page 38

- 39.

116 C ache Valley Air Quality Studies

- A Summary of Research Conducted through 2006, Dr. Randy Martin Department of Civil & Environmental Engineer ing, Utah State University. August 2006.

117 Ibid.

118 Cache Valley Ida ho PM 2.5 Nonattainment Area State Implementation Plan, State of Idaho Department of Environmental Quality, December 2012. At page 39.

46targeted at reducing NOx emissions from home heating combustion would be considered

small. 119 However, Idaho evaluated the effectiveness of establishing additional controls on NOx

emissions from mobile sources in order to impact the secondary chemistry of ammonium nitrate

formation. 120 Idaho determined that a n Inspection and Maintenance ( I & M ) program for motor vehicles in Franklin County would be e x pected to reduce NOx emissions by 4.6%

, based on modeling conducted by Utah and Idaho for the airshed

. 121 Idaho calculated that Franklin County

NOx emissions from mobile sources in 2008 were 0

. 88 tons/day and that a 4

. 6 % reduction in

emissions would equate to an estimated 0

. 04 tons/day or 15 t ons /year

. Idaho estimated the cost per ton of NOx reduced would be at least $20

, 000/ton. 122 In reviewing the cost per ton
reductions in NOx expected from implementing an I & M program in Franklin County , the EPA

has determined that the cost is double any cost thresh olds considered for NOx in the Transport

Rule. 123

VOCs play a n important role in secondary PM 2.5 formation in the Cache Valley as a whole

. In

the December 2012 submittal, Idaho provided an inventory of VOC emissions

. See Figure 2 1

above. Idaho stated that there are no major stationary sources of VOCs on the Idaho side of the Cache Valley

, defined as large industrial sources with the potential to emit annually over 100

tons or more. 124 Idaho’s December 2012 submittal notes that reductions in VOCs are expect ed from Federal motor vehicle emissions regulations that went into effect on April 10, 2000 and

were phased in between 2004 and 2008

. 125 The Tier 2 regulations introduced more stringent numerical emission limits compared to the previous program (Tier 1 ) and also required refiners to reduce ga soline sulfur levels nationwide. 126 The EPA estimated that the Tier 2 regulations will reduce nitrogen oxide emissions by at least 2,220,000 tons per year nationwide in 2020. 127 Tier 2 also impacts VOC s and direct particulate matter emissions from light

- duty vehicles. In addition to the reductions expected from the Tier 2 rules, Idaho asserts that reductions in both VOC s and

NOx will be realized as older v ehicles are replaced with Tier 2 vehicles

– thro ugh fleet

turnover

. 128

Idaho’s December 2012 submittal also asserted that a dditional on

‐ road mobile source emis sions improvements will stem from F ederal regulations for heavy

- duty diesel vehicles. EPA’s Clean Air Highway Diesel Rule, which aimed at reducing pollution from heavy

‐ duty diesel highway vehicles, was published January 18, 2001 ( 66 FR 5002 )

. Under the rule, beginning in 2007 (with a phase

‐ in through 2010) heavy

‐ duty diesel highway vehicle emissions were required to be

119 Cache Valley Idaho PM 2.5 Nonattainment Area State Implementation Plan, State of Idaho Department of Environmental Qualit y, December 2012. At page 39.

120 C ache Valley Air Quality Studies

- A Summary of Research Conducted through 2006, Dr. Randy Martin Department of Civil & Environmental Engineer ing, Utah State University. August 2006.

121 Cache Valley Idaho PM 2.5 Nonattainment Area State Implementation Plan, State of Idaho Department of Environmental Quality, December 2012. Appendix C.

122 Ibid. at Appendix C.

123 The Transport Rule did not quantify the costs per ton of reduced VOCs.

124 Ibid. at page 39.

125 Ibid. at page 43

- 44.

126 Ibid. at page 43

- 44.

127 Control of Air Pollution From New Motor Vehicles: Tier 2 Motor Vehicle Emissions Standards and Gasoline Sulfur Control Requirements

, published February 10, 2000 (65 FR 6698) (Tier 2)

. 128 Ibid.

47reduced by as much 90% with a goal of complete fleet replacement by 2030

. To enable the updated emission reduction technologies necessitated by the rule, beginning in 2006 (with a phase

‐ in through 2009) refiners were required to begin producing cleaner

‐ burning ultra

‐ low

sulfur diesel f uel. Specifically, the rule required a 97% reduction in sulfur content from 500 parts per million (ppm) to 15 ppm. The overall nationwide effect of the rule is estimated to be equivalent to removing the pollution from over 90% of trucks and buses when the fleet turnover is completed in 2030 ( 66 FR 5002).

With respect to precursor emission from agricultural sources, Idaho provide d information on existing

Federal efforts to address agricultural sources under the Food Security Act of 1985, reauthorized in

19 96, 2002, 2008, and 2012, including best management practices and land conservation practices. 129

In addition, the submittal asserted that Idaho’s crop residue burning program controls impacts from agricultural burning so that air quality standards are attained and maintained. While crop residue burning does not generally occur in the winter months, Idaho stated that the rules restrict when burning is allowed. Specifically, burning cannot occur if concentrations are forecasted to reach 75%

of the N AAQS or when dispersion characteristics are unfavorable. 130

With respect to potential impacts of additional SO 2 controls, the State’s December 2012,

submittal asserted that SO 2 emissions make up a very small portion of the overall inventory on the Idaho sid e of the Cache Valley, less than 0.15 tons per episode day. Fuel combustion sources including mobile sources generate SO 2 and is impacted by Federal mobile source rules including the requirements to reduce the sulfur content of fuels. See Figure 2 3 above.

Direct PM 2.5 emissions also play a role in Cache Valley 24

- hour PM 2.5 exceedances. Figure 2 4 above shows that major sources of direct PM 2.5 inclu de residential fuel combustion and road dust

from mobile sources

. 131

In the attainment planning pr ocess and submitted as part of the December 2012 submittal, Idaho

established controls on direct PM 2.5 emissions from residential home heating and road sanding to

reduce PM 2.5 emissions on the Idaho side of the Cache Valley. Idaho began implementing the

c ontrols in 2012, and the EPA approved them into the Idaho SIP as a SIP strengthening measure on March 25, 2014 (79 FR 16201). It is important to clarify that this March 2014 action approved the controls in a limited fashion

– adding them to the SIP to str engthen overall control

of PM 2.5 emissions, but not making a determination whether the controls met the requirements of part D, title I of the CAA.

129 Ibid. at page 40 and Appendix C.

130 Ibid. at page 40.

131 Ibid. at page 40.

48Figure 2 5 : Franklin County PM 2.5 Emissions 132

Idaho focused on direct PM 2.5 emissions for control efforts and, in particular, targeted the two sources that make up 84% of those emissions (mobile source road dust and woodstoves)

. 133 See Figure 2 5 above. On the Idaho side of the Cache Valley, Idaho asserted that approximately 70% of the directly emitted PM 2.5 is due to mobile dust, which is primarily from re

- entrained dust on paved roads. Franklin County Road and Bridge and I daho Transportation Department have entered into road sanding agreements and these agreements were submitte d and approved into

the SIP as a strengthening measure on March 25, 2014 (79 FR 16201). The Franklin Road and Bridge agreement reduces the amount of sand used on paved roads by applying brine, when conditions are appropriate, and by using a salt/sand mixt ure where antiskid treatment is required.

I daho Transportation Department has moved to applying a straight solution of sodium chloride, thereby eliminating the amount of sanding material. Franklin County Road and Bridge has used a

10

- to

- 1 ratio of sand to salt in past years; however, they have now agreed to use a 4

- to

- 1 sand

- to

salt ratio mix when antiskid treatment is required. In addition, brine will be applied when

132 Source: Idaho Department of Environmental Quality.

133 Cache Valley Idaho PM 2.5 Nonattainment Area State Implementation Plan, State of Idaho Department of Environmental Quality, December 2012. At page 30

.

49temperatures are above 22 degrees Fahrenheit, a measure which further reduces the amount o f sand required by approximately 50%. 134

Idaho established residential wood combustion ordinances in the six Idaho cities that lie within the Idaho side of the Cache Valley (Franklin, Preston, Weston, Dayton, Clifton, and Oxford). 135 Key elements in the ordinances include issuing a mandatory burn ban when PM 2.5 is at, or is forecasted to reach 75 on the Air Quality Index. This corresponds directly to a PM 2.5 concentration of 25.4 μg/m 3

. All of the cities and the unincorporated Frankli n County have existing ordinances prohibiting both open burning and the use of a device when an air quality alert is issued. The ordinances also prohibit installing non EPA

- certified devices. 136

We propose to determine that the controls established by Idaho in Franklin County and approved

into the Idaho SIP are those that are reasonably cost

- effective for purposes of CAA section 110(a)(2)(D)(i)(I). The Supreme Court recently upheld the EPA’s use of cost in determining state obligations with respect to CAA s ection 110(a)(2)(D)(i)(I) in the Transport Rule

. 137 EPA v. EME Homer City Generation, L.P.

, 134 S.Ct. 1584,1607 (2014). “Using costs in the Transport Rule calculus, we agree with EPA, also makes good sense. Eliminating those amounts that can

cost

- effectively be reduced i s an efficient and equitable solution to the allocation problem the Good Neighbor Provision requires the Agency to address. Efficient because EPA can achieve the levels of attainment, i.e., of emission reductions, the proporti onal approach aims to achieve, but at a much lower overall cost. Equitable because, by imposing uniform cost thresholds on regulated States, EPA’s rule subjects to stricter regulation those States that have done relatively less in the past to control thei r p ollution. ” Id.

In the Transport Rule, “EPA identified what emission reductions were available at various cost thresholds, quantifying emission reductions that would occur within each state at ascending costs per ton of emission reductions. In other w ords, EPA determined for specific cost per ton thresholds, the emission reductions that would be achieved in a state if all EGUs greater than 25

MW in that state used all emission controls and emission reduction measures available at that

cost threshold.” 75 FR 48208, 48248 (August 8, 2011). EPA then used an air quality assessment tool “to estimate the impact that the combined reductions available from upwind contributing states and the downwind receptor state at different cost

- per

- ton levels would have o n air quality at downwind” receptors.” Id. at 48249. Finally, the EPA examined cost and air quality information to identify “significant cost thresholds . . . where a noticeable change occurred in downwind air quality.” Id. This information was then us ed to determine each state’s “budget.”

Id. For upwind states linked to downwind sites for PM 2.5 transport, the EPA examined cost levels ranging from $500 to $2,500 per ton for NOx, 75 FR at 48249

- 50, and between $500 and $10,000 per ton for SO 2 , id. at 48251. For annual NOx, the EPA determined that $500/ton was the appropriate cost threshold for the rule. Id. at 48257. For SO 2 , the EPA assessed reductions available first at $500/ton, and where downwind nonattainment and maintenance problems were

134 Ibid

. at page 39.

135 Ibid. Appendix E.

136 Ibid. at page 40.

137 The State of Idaho was not covered by either CAIR or the Transport Rule, and the EPA made no determinations in either rule regarding whether emissions from sources in Idaho significantly contr ibute to nonattainment or

interfere with maintenance of the 2006 24

- hour PM 2.5 NAAQS in another state.

50n ot resolved at that threshold, examined outcomes at increasing thresholds, ultimately resolving that significant air quality outcomes were achieved at a cost threshold of $2,300/ton. Reductions in excess of $2,300/ton were not as cost

- effective under the circumstances

. The EPA concluded

that it was reasonable to seek reductions for SO 2 up to a cost of $2,300/ton. Id., at 48259. Although the EPA acknowledged in the Transport Rule that specific cost thresholds do not necessarily establish any precedent for the cost per ton stringency of reduction it might require in the future, 75 FR at 48249 n.42, the analysis is instructive to an evaluation of controls available to Idaho to address emissions which might contribute to nonattainment or interfere with

mainten ance on the Utah side of Cache Valley.

We are thus proposing to determine that Idaho has met the requirements of CAA section 110(a)(2)(D)(i)(I) for the 2006 24

- hour PM 2.5 NAAQS with respect to Utah, including the Cache Valley. However, we note that we are not making a determination whether Idaho has met the requirements for purposes of attainment planning under part D, title I of the CAA. We will address the requirement of par t D in a separate action.

I II

. C . Transport to Eastern States

The EPA has also considered potential PM 2.5 transport from Idaho emission sources to the nearest potential receptor located in the eastern , midwestern, and southern states within the domain of the modeling analysis for the Transport Rule (76 FR 48208)

. The receptor nearest to
Idaho evaluated in the Transport Rule modeling analysis is Madison County

, Illinois

. We note,

t he Transport Rule modeling did not analyze the contribution of Idaho sources to Madison County, Illinois. Thus, we have analyzed the magnitude of Idaho’s SO 2 and NOx emissions relative to states found to have emissions that significantly contribute to nonattainment at tha t
receptor. The EPA also considered the distance from Idaho to Madison County, Illinois relative to states found to significantly contribute there.

We believe that the following factors support a finding that emissions from Idaho sources do not significantly contribute to nonattainment of the 2006 24

- hour PM 2.5 NAAQS at the Madison County, Illinois receptor: (1) the relatively small magnitude of the emission inventory of PM 2.5 precursors (SO 2 and NOx) in Idaho as detailed below , combined with (2) the relatively long

distance between the s tate of Idaho and th is receptor (> 1000 miles)

. The EPA believes that these factors also support a finding that emissions from Idaho sources do not significantly

contr ibute to nonattainment of the 2006 24

- hour PM 2.5 NAAQS at any of the other Transport

Rule receptors f a rther east.

In the Transport Rule analysis

, the EPA did not quantify the PM 2.5 contributions from Idaho to Illinois or any of the other Eastern nonattainment and maintenance receptors modeled as par t of the Transport Rule . However, we can make a qualitative conclusion about the likely contribution

from Idaho to Illinois and point s f a rther east by comparing the Idaho emissions to a state that

was modeled in the Transport Rule

. Minnesota was modeled for the Transport Rule , and was found below the threshold of significant contribution to downwind nonattainment and

interference with maintenance of the 24

- hour PM 2.5 NAAQS for all receptors modeled for the Transport Rule

. We ha ve ev aluated the relative amounts of PM 2.5 precursor (SO 2 and NOx)

emissions in Idaho compared to the amounts of PM 2.5 precursor emission in Minnesota, as

modeled in the “2012 Transport Rule Base Case.”

51The emission inventories used in the Transport Rule mode ling analysis indicate that SO 2 emissions in Idaho are about 22 % of SO 2 emissions in Minnesota and NOx emissions in Idaho

are about 29 % of NOx emissions in Minnesota. Specifically, t he Transport Rule 2012 Base C ase inventories 138 provide the following state wide emissions inventory data for these two states : 24,326 tons of SO 2 and 105,888 tons of NOx from Idaho emission sources , compared to 109,940

tons of SO 2 and 364,052 tons of NOx from Minnesota emission sources

. Even though the relationship between upwind emissions and downwind secondary PM 2.5 formation is not linear, we would expect the Idaho PM 2.5 contribution to Illinois to be much less than that of Minnesota

and well below the 1% threshold applied in the initi al screening stage of the T ransport R ule

. In addition, Idaho is a much greater distance away from Madison County, Illinois than Minnesota ( > 1000 miles vs approximately 300 miles)

. The distance from Idaho to the other eastern receptors is even greater, and therefore, the expected impact somewhat smaller.

Given all of these factors, the EPA believes it is reasonable to conclude that emissions from

Idaho sources do not contribute significantly to nonattainment of the 2006 24

- hour PM 2.5 NAAQS at identifie d receptors in any eastern state

.

I V. Transport Assessment for Maintenance Receptors

I V. A. Introduction

Based on our methodology for selecting ma intenance receptors described in s ection II.A above,

we have evaluated maintenance receptors in the following w estern states: California , Montana,

and Utah. We also evaluated the nearest eastern receptor evaluated in the Transport Rule modeling domain. 139

I V. B. Transport to Western State s

IV.B.1. California

Southern California

– Los Angeles County Maintenance Receptor (Site 060370002)

The high 24

- hour PM 2.5 concentrations in the South Coast Air Basin and at this maintenance

receptor are mainly due to the secondary formation of smaller particulates resulting from mobile,

stationar y and area source emissions of precursor gases (i.e., NOx, SOx, ammonia ( NH 4 ), and

VOC s ) that are converted to PM in the atmosphere. Speciated PM 2.5 data at the Central Los Angeles Site (C E LA) and the Rubi doux site (RIVR) indicate that o rganic c arbon, a mm onium

n itrate, and a mmonium s ulfate constitute the major components at each site . See Figures 2 6 and

27 below. 24

- hour PM 2.5 design value trends show strong downward trend s at all sites in the

Sou th Coast Basin. 140 See Figur e 28 below.

138 See “Emissions Inventory Final Rule TSD,” Technical Support Document (TSD) for the final Transport Rule,

Docket ID No. EPA

- HQ

- OAR

- 2009

- 0491, June 28, 2011, at Tables 7

- 1 and 7

- 2.

139 Madison County, Illinois. See “ Technical Support Document (TSD) for the final Transport Rule, Docket ID No.

EPA

- HQ

- O AR

- 2009

- 0491, June 28, 2011

. 140 Joe Cassmassi, Scientific, Technical & Modeling Peer Review ( STMPR ) Adviso ry Group Meeting, September
22, 2011

.

52Figure 2 6 : Speciated data for the Central Los Angeles Site 141

141 STMPR Item # 5

- 2008 PM2.5 Air Quality Characterization, January 19, 2012. Bong

- Mann Kim

.

53Figure 27 : Speciated data for Roubidoux site at Riverside 142

142 Ibid.

54Figure 28 : 24

- hour PM 2.5 Design Value Trends

PM 2.5 is essentially a combustion generated pollutant due to the volume of traffic flow and numbers of sources (both point and area) in the region. It is important to note that the areas with the highest concentrations are directly downwind of a n area with major ammonia source s associated with dairies and poultry farming. 143

The South Coast Air Quality 2012 Air Quality Management Plan 144 air quality projections show that the emission control strategy outlined in the plan will result in air quality improvement at each of the nonattainment receptors in the plan , and that each of these sites will attain the

standard in 2014 or sooner

. See Figure 29 : Maximum 24

- Hour Average PM 2.5 Design Concentrations: 2008 Baseline, 2014 and 2014 Controlled

.

143 Final 2012 Air Quality Management Plan (AQMP), Appendix V

– Modeling and Attainment Demonstrations February, 2013.

144 http://www.aqmd.gov/home/library/clean

- air

- plans

55Figure 29 : Maximum 24

- Hour Avera ge PM 2.5 Design Concentrations: 2008 Baseline, 2014

, and 2014 Co ntrolled 145

Based on the air quality trends and projections that indicate that th e above

- referenced emission

strategy will be effective in reducing 24

- hour PM 2.5 levels at these receptors, the distance from

Idaho to these receptor (> 500 miles), and the significant intervening terrain including the Sierra Nevada and Cascade Ranges ( See Figure 9 above) we believe it is reasonable to conclude that

emissions from Idaho do not interfere with maintenance of the 2006 24

- hour PM 2.5 NAAQS at

t hese receptors.

I V.B. 2

. Montana

Lewis and Clark County Maintenance Receptor (Helena) (Site 300490026)

Elevated levels of PM 2.5 in the Helena area occur primarily in the winter months. 146 The Helena Valley is topographically prone to cold pool inversion conditions during the winter months. 147
The mountains of the Lewis Range and the Bitteroot Range are situated to the west of Helena, between Idaho and this receptor. See Figure 3 0 below. Speciation data indicates that emissions from wood smoke are the prima ry contributor to exceedances of the PM 2.5 standard in Helena. 148
In the months when violations of the NAAQS occurred at the Helena receptor, the nearby Gate

145 Source: South Coast Air Quality Management District. http://www.aqmd.gov/home/library/clean

- air

- plans

146 The maintenance receptor in Helena, MT violated the 2006 PM 2.5 NAAQS only in 2010. Each of the exceedances

of the 2006 PM 2.5 standard at this receptor during 2010 occurred during the winter months, with all but one exceedance occurring in December or January. Monitor values are accessible on EPA’s AirData website, http://www.epa.gov/airquality/airdata/

. 147 Johnson, J. “Case Study of a Persistent Cold Pool in the Helena Valley.” NOAA. November 21, 2000.

148 Ward, T., Lange, T

. , “The impact of wood smoke on ambient PM 2.5 in northern Rocky Mountain valley communities.” Environmental Pollution 158 (2010) 723

– 729

.

56of the Mountains Wilderness Area monitor did not exceed 2 μg/m 3

. 149 All of these factors taken togethe r indicate that high levels of PM 2.5 in Helena build as emissions become trapped during

wintertime inversions.

Figure 3 0 : Map of Montana 150

Given the characteristics of the elevated PM 2.5 levels at this receptor, air quality data indicating that regional background levels of PM 2.5 are generally low at IMPROVE monitors in class I areas near this receptor 151 during the time periods of elevated PM 2.5 , and the intervening topography between Idaho and this receptor, as sh own in the map above , we believe it is

reasonable to conclude that emissions from Idaho sources do not interfere with maintenance of

the 2006 24

- hour PM 2.5 standard s at this receptor location.

IV.B. 3

. Utah

Davis and Weber Counties Maintenance Receptors (Greater Salt Lake City) (Sites 490110004

and 490571003)

We note that the EPA identified both nonattainment and maintenance receptors in Greater Salt Lake City. Therefore, we have included our evaluation in both sections.

149 The Gate of the Mountains IMRPOVE monitor is located roughly 17 miles from Helena, MT. The IMPROVE

monitor data can be found in section V. Appendix to this TSD and http://vista.cira.colostate.edu/TSS/Results/HazePlanning.aspx

150 Source: University of Texas. http://www.lib.utexas.edu

151 Craters of the Moon, ID, Sawtooth Nati onal Forest, ID, Sula Peak Wilderness Area, MT, Gate of the Mountains Wilderness Area, MT. See section V. Appendix to this TSD and http://vista.cira.colostate.edu/TSS/Results/Haz ePlanning.aspx

57Portions of Davis and Weber c ounties are designated as part of the Salt Lake City (SLC) 2006

24

- hour PM 2.5 nonattainment area (NAA)

. 152 The EPA identified maintenance receptors in these

two counties. The SLC NAA and these maintenance receptors are situated in a valley bordered

on the w est by the Stansbury Mountains, 153 Promontory Mountains and Great Salt Lake, and on

the e ast by the Wasatch Front. Like the other low

- lying valleys just west of the Wasatch Front, the topography of the Salt Lake valley makes it prone to temperature inversions. See Figure 3 1

below.

A western topographic airshed barrier for eastern Davis County involves the Promontory Mountains and North Promontory Mountains. 154 The Promontory Mountains are located approximately 24 miles west of both Brigham City and Ogden and show approximate altitudes of 5,600 ft. (MSL) in the south (extending into the Great Salt Lake), areas of over 6,000 ft. (MSL) in the middle, and 5,000 ft. to the North where they meet the southern end of the North

P romontory Mountains. The southern end of the North Promontory Mountains are approximately 5,000 ft. (MSL) and are also approximately 5,000 ft. (MSL) to the north (northwest of Howell, UT.) 155

The Stansbury Mountains are located approximately 17 miles west of Tooele City (approximately 43 miles southwest of Salt Lake City) and show approximate altitudes of 8,300 ft. (MSL) in the south, areas 7,000 ft. (MSL) to over 9,500 ft. (MSL) in the middle, and 5,000 ft. (MSL) to the North where they meet the Great Salt Lake. Also, an impediment to airflow in this area includes the South Mountain ridge located at the southern end of the Tooele Valley. This ridge essentially connects the Stansbury Mountains to the Oquirrh Mountains and has a maximum height of approximatel y 6,500 ft. (MSL). Therefore, it is likely that Salt Lake County is contributing to Utah County’s high concentration PM 2.5 violations and that Utah County is contributing to Salt Lake County’s high concentration PM 2.5 violations. 156

During inversions, the S LC NAA becomes a closed airshed (save for potential transport between the Salt Lake City and Provo NAAs) featuring stagnant air masses and light winds which typically oscillate back and forth within the airshed. As the airshed is essentially capped during inversions, PM 2.5 is formed in

- situ (and trapped) via fresh emission sources and secondary chemistry. 157 Speciation data from wintertime PM 2.5 exceedance days from 2004

- 2006 showed the average composition of PM 2.5 in Salt Lake City is 58% ammonium nitrate, 3 1% carbon and organic compounds, 8% ammonium sulfate, and 2% crustal. Several factors, including significant amounts of emissions from mobile, point and area sources

, contribute to primary and

152 2006 24

- Hour PM 2.5 NAAQS Designations (74 FR 58688, November 13, 2009), Technical Support Document,

December 2008. http://www.epa.gov/pmdesignations/2006standards/final/TSD/tsd_4.0_4.8_4.8.2_r08_UT.pdf

. 153 The Quqirrh Mountains lie between the Wasatch Front and the Stansbury Mountains. However, EPA determined that some area located west of the Quqirrh Mountains should s till be considered part of the SLC nonattainment area.

154 2006 24

- Hour PM 2.5 NAAQS Designations (74 FR 58688, November 13, 2009), Technical Support Document,

December 2008. http://www.epa.gov/pmdesignations/2006standards/final/TSD/tsd_4.0_4.8_4.8.2_r08_UT.pdf

. at page 48.

155 Ibid. at page 48.

156 Ibid. at page 49.

157 Ibid. at page 34.

58secondarily formed PM 2.5 that violate the 2006 24

- hour PM 2.5 st andard during stable weather events associated with strong inversions. 158

Figure 3 1 : Monitoring Network with Counties and Topography 159

158 Ibid. at page 53.

159 Source: Utah Department of Environmental Quality. 2006 24

- Hour PM 2.5 NAAQS Designations (74 FR 58688, November 13, 2009), Technical Support Document, December 2008. http://www.epa.gov/pmdesignations/2006standards/final/TSD/tsd_4.0_4.8_4.8.2_r08_UT.pdf . At page 19.

59Based on the meteorology, topography and characteristics of the PM 2.5 levels during time periods

when the 24

- hour PM 2.5 standard is exceeded, as described above, as well as the low levels of background PM 2.5 during these time periods at IMPROVE monito rs at class I areas near this receptor and Idaho 160 we believe it is reasonable to conclude that emissions from Idaho do no t
interfere with maintenance of the 2006 24

- hour PM 2.5 NAAQS at these receptors.

I V. C. Transport to Eastern States

The EPA has also considered potential PM 2.5 transport from Idaho emission sources to the nearest potential receptor located in the eastern

, midwestern, and southern states within the domain of the modeling analysis for the Transport Rule (76 FR 48208)

. The receptor nearest to
Idaho evaluated in the Transport Rule modeling analysis is Madison County, Illinois. We note, the Transport Rule mod eling did not analyze the contribution of Idaho sources to Madison County, Illinois. Thus, we have analyzed the magnitude of Idaho’s SO 2 and NOx emissions relative to states found to have emissions that significantly contribute to nonattainment at that

re ceptor. The EPA also considered the distance from Idaho to Madison County, Illinois relative to states found to significantly contribute there.

We believe that the following factors support a finding that emissions from Idaho sources do not

interfere wi th maintenance of the 2006 24

- hour PM 2.5 NAAQS at the Madison County, Illinois receptor: (1) the relatively small magnitude of the emission inventory of PM 2.5 precursors (SO 2 and NOx) in Idaho as detailed in the paragraph below, combined with (2) the relatively long distance between the state of Idaho and this receptor (> 1000 miles). The EPA believes that these factors also support a finding that emissions from Idaho sources do not interfere with

maintenance of the 2006 24

- hour PM 2.5 NAAQS at any of the other Transport Rule receptors

farther east.

In the Transport Rule analysis, the EPA did not quantify the PM 2.5 contributions from Idaho to Illinois or any of the other Easte rn receptors modeled as part of the Transport Rule. However, we can make a qualitative conclusion about the likely contribution from Idaho to Illinois and points farther east by comparing the Idaho emissions to a state that was modeled in the Transport

Ru le. Minnesota was modeled for the Transport Rule, and was found below the threshold of significant contribution to downwind nonattainment and interference with maintenance of the

24

- hour PM 2.5 NAAQS for all receptors modeled for the Transport Rule. We ha ve evaluated the

relative amounts of PM 2.5 precursor (SO 2 and NOx) emissions in Idaho compared to the amounts

of PM 2.5 precursor emission in Minnesota, as modeled in the “2012 Transport Rule Base Case.”

The emission inventories used in the Transport Rule modeling analysis indicate that SO 2 emissions in Idaho are about 22% of SO 2 emissions in Minnesota and NOx emissions in Idaho

are about 29% of NOx emissions in Minnesota. Specifically, the Transport Rule 2012 Base Case

160 IMPROVE monitoring network at Craters of the Moon, ID, Sawtooth National Forest , ID and Jarbidge

Wilderness Area , NV. See section V. Appendix to this TS D and http://vista.cira.colostate.edu/TSS/Results/HazePlanning.aspx

60inventories 161 provide the following statewide emissions inventory data for these two states: 24,326 tons of SO 2 and 105,888 tons of NOx from Idaho emission sources, compared to 109,940

tons of SO 2 and 364,052 tons of NOx from Minnesota emission sources. Even though the relationship between u pwind emissions and downwind secondary PM 2.5 formation is not linear, we would expect the Idaho PM 2.5 contribution to Illinois to be much less than that of Minnesota

and well below the 1% threshold applied in the initial screening stage of the Transport Ru le

. In addition, Idaho is a much greater distance away from Madison County, Illinois than Minnesota (> 1000 miles vs approximately 300 miles). The distance from Idaho to the other eastern receptors is even greater, and therefore, the expected impact somewhat smaller.

Given all of these factors, the EPA believes it is reasonable to conclude that emissions from

Idaho sources do not interfere with maintenance of the 2006 24

- hour PM 2.5 NAAQS at identified receptors in any eastern state.

V. Appendix

– PM 2.5 IMPROVE Data

1. Overview and Map of IMPROVE Monitoring Sites

IMPROVE Monitoring Program Overview

The Interagency Monitoring of Protected Visual Environments (IMPROVE) program is a cooperative measurement effort governed by a steering committee co mposed of representatives from Federal and regional

- state organizations. The IMPROVE monitoring program was established in 1985 to aid the creation of Federal and State implementation plans for the protection of visibility in class I areas ( 156 national parks and wilderness areas ) as stipulated in

the 1977 amendments to the Clean Air Act

. 162

The objectives of IMPROVE include: (1) establishing current visibility and aerosol conditions in mandatory class I areas; and (2) identifying chemical species and emission source s responsible for existing man

- made visibility impairment.

The particulate monitoring portion of the IMPROVE program measures the concentration of the fine (PM 2.5 ) particles for mass, optical absorption, major and trace elements, organic and

elemental car bon, and nitrate and of PM 10 particles for mass. Prior to 2000, IMPROVE sites collect two samples per week, on Wednesday and Saturday. With the implementation of the Regional Haze Rule the IMPROVE program changed to a 1

- in

- 3 day schedule.

IMPROVE Monitoring Data

161 See “Emissions Inventory Final Rule TSD,” Technical Support Document (TSD) for the final Transport Rule,

Doc ket ID No. EPA

- HQ

- OAR

- 2009

- 0491, June 28, 2011, at Tables 7

- 1 and 7

- 2.

162 http://vista.cira.colostate.edu/improve/Overview/IMPROVEProgram_files/frame.htm

61The data for this report was obtained from the website http://views.cira.colostate.edu/web/

. The graphs in this report show the PM 2.5 (fine) mass monitor values from 2009 to 2013 at selected IMPROVE monitoring locations.

Additional data, such as the chemical composition data in the graph shown below, is also

available as the http://views.cira.colostate.edu/web/ site, using the composition tool.

State National Parks, Monuments and Wilderness Areas (identifier on IMPROVE Network Map)

Idaho (and Idaho/Oregon Border) Craters of the Moon National Monument (69), Sawtooth

Wilderness (70), Hells Canyon Wilderness (77), Starkey (76)

Montana Sula Peak (71) , Cabinet Mountains W ilderness Area (75) , Gate

of the Mountains W ilderness Area (74)

Nevada Jarbidge Wilderness Area (68)

, Great Basin National Park (116)

Utah Bryce Canyon National Park (51), Canyonlands (50), Capitol

Reef National Park (52), Zion (49) Wyoming Bridger Wilderness (65) , North Absaroka W ilderness A rea (67) , Yellowstone N ational Park 2 (66)

California

- Oregon Border Crater Lake (86), Lava Beds National Monument (87), Lassen Volcanic National Park (90) Oregon/Washington Border Mount Hoo d (85)

, Columbia River Gorge (112)

Source: http://vista.cira.colostate.edu/improve/Overview/IMPROVENetworkExp.htm

6263

### 2. Idaho and Idaho/Oregon Border

– IMPROVE Data for the Years 200 9

- 2013

Craters of the Moon National Monument , ID

Sawtooth Wilderness , ID

64Hells Canyon Wilderness , ID

Starkey, OR

65

### 3. Montana

- IMPROVE Data for the Years 200 9

- 2013

Sula Peak, MT

Cabinets Mountains Wilderness , MT

66Gates of the Mountains Wilderness, MT



### 4. Nevada

- IMPROVE Data for the Years 200 9

- 2013

Jarbidge Wilderness , NV

67Great Basin National Park , NV



### 5. Utah

– IMPROVE Data for the Years 2009

- 2013

Bryce Canyon National Park , UT

68Canyonlands National Park, UT

Capitol Reef National Park , UT

69Zion Canyon, UT



### 6. Wyoming

- IMPROVE Data for the Years 200 9

- 201 3

Bridger Wilderness , WY

70North Absaroka Wilderness, WY



### Yellowstone National Park 2, WY

71

### 7. California/Oregon Border

– IMPROVE Data for the Years 200 9

- 201 3

Crater Lake National Park, OR

Lava Beds National Monument, CA

72Lassen Volcanic National Park, CA



### 8 . Oregon /Washington Border

– IMPROVE Data for the Years 200 9

- 201 3

Mount Hood Wilderness, OR

73Columbia River Gorge, OR

74