Federal Register / Vol. 75, No. 227 / Friday, November 26, 2010 / Rules and Regulations 72705 

EPA-APPROVED OKLAHOMA REGULATIONS—Continued 

State citation Title/subject State effective 

date EPA approval date Explanation 

PART 9. MAJOR SOURCES AFFECTING NONATTAINMENT AREAS 

252:100–8–50 .. Applicability ......................................... 6/11/2001 11/26/2010 [Insert FR page number 

where document begins].

252:100–8–51 .. Definitions ........................................... 6/11/2001 11/26/2010 [Insert FR page number 

where document begins].

252:100–8–52 .. Source applicability determination ...... 6/11/2001 11/26/2010 [Insert FR page number 

where document begins].

NOT in SIP: paragraph 

(b)(2). 

252:100–8–53 .. Exemptions ......................................... 6/11/2001 11/26/2010 [Insert FR page number 

where document begins].

252:100–8–54 .. Requirements for sources located in 

nonattainment areas PSD or NNSR 

program submissions containing 

rule changes for PM2.5.

6/11/2001 11/26/2010 [Insert FR page number 

where document begins].

*******

1Submitted. 

* * * * * (e) * * * 

EPA-APPROVED NONREGULATORY PROVISIONS AND QUASI-REGULATORY MEASURES IN THE OKLAHOMA SIP 

Name of SIP provision 

Applicable geographic or nonattainment area State 

submittal 

date 

EPA approval date Explanation 

*******

Interstate transport for the 1997 

ozone and PM2.5 NAAQS.

Statewide ............ 5/1/2007 11/26/2010 

[Insert citation of 

publication]. 

Approval for revisions to prohibit 

interference with Prevention of 

Significant Deterioration in any 

other State. 

[FR Doc. 2010–29398 Filed 11–24–10; 8:45 am] 

BILLING CODE 6560–50–P 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Part 52 

[EPA–R10–OAR–2010–0669; FRL–9231–2] 

Approval and Promulgation of 

Implementation Plans; Idaho 

AGENCY: Environmental Protection 

Agency. 

ACTION: Final rule. 

SUMMARY: EPA is approving a State 

Implementation Plan (SIP) revision 

submitted by the State for Idaho for the 

purpose of addressing the ‘‘good 

neighbor’’ provisions of the Clean Air 

Act (the Act or CAA) section 

110(a)(2)(D)(i) for the 1997 8-hour ozone 

National Ambient Air Quality Standards 

(NAAQS or standards) and the 1997 

PM2.5 NAAQS. This SIP revision 

addresses the requirement that the State 

of Idaho’s SIP have adequate provisions 

to prohibit air emissions from adversely 

affecting another state’s air quality 

through interstate transport. In this 

action, EPA is approving the Idaho 

Interstate Transport SIP provisions that 

address the requirement of section 

110(a)(2)(D)(i) that emissions from Idaho 

sources do not significantly contribute 

to nonattainment of the 1997 8-hour 

ozone NAAQS and the 1997 PM2.5

NAAQS in any other state, interfere 

with maintenance of the 1997 8-hour 

ozone NAAQS and the 1997 PM2.5

NAAQS in any other state, and interfere 

with measures required in the SIP of 

any other state under part C of 

subchapter I of the CAA to prevent 

significant deterioration of air quality. 

This action is being taken under section 

110 and part C of subchapter I of the 

CAA. 

DATES: This action is effective on 

December 27, 2010. 

ADDRESSES: Copies of the State’s SIP 

revision and other information 

supporting this action are available for 

inspection at EPA Region 10, Office of 

Air, Waste, and Toxics (AWT–107), 

1200 Sixth Avenue, Suite 900, Seattle, 

Washington 98101. 

FOR FURTHER INFORMATION CONTACT: 

Donna Deneen, EPA Region 10, Office of 

Air, Waste, and Toxics (AWT–107), 

1200 Sixth Avenue, Seattle, Washington 

98101, or at (206) 553–6706. 

SUPPLEMENTARY INFORMATION: 

Throughout this document wherever 

‘‘we’’, ‘‘us’’ or ‘‘our’’ are used, we mean 

EPA. Information is organized as 

follows: 

Table of Contents 

I. What action is EPA taking? 

II. What is the background for this action? 

III. Response to Comments 

A. Comments Relating to the ‘‘Significant 

Contribution to Nonattainment’’ Element 

B. Comments Relating to the ‘‘Interfere 

With Maintenance’’ Element 

C. Comment Relating to Section 110(l) 

IV. Final Action 

V. Scope of Action 

I. What action is EPA taking? 

EPA is approving a portion of Idaho’s 

Interstate Transport State 

Implementation Plan (SIP) revision for 

the 1997 8-hour ozone and 1997 PM2.5

NAAQS submitted by the Idaho 

Department of Quality (IDEQ) on June 

28, 2010. Specifically, we are approving 

the portion of the plan that addresses 


srobinson on DSKHWCL6B1PROD with RULES
72706 Federal Register / Vol. 75, No. 227 / Friday, November 26, 2010 / Rules and Regulations 

1The PM2.5 standard was revised in 2006. See 

‘‘National Ambient Air Quality Standards for 

Particulate Matter,’’ at 71 FR 61144 (October 17, 

2006). 

the following elements of CAA section 

110(a)(2)(D)(i): (1) Significant 

contribution to nonattainment of these 

NAAQS in any other state, (2) 

interference with maintenance of these 

NAAQS by any other state, and (3) 

interference with any other state’s 

required measures to prevent significant 

deterioration (PSD) of its air quality 

with respect to these NAAQS. IDEQ 

addressed element (4), interference with 

any other state’s required measures to 

protect visibility, by referring to its 

Regional Haze SIP, which will be 

submitted separately. EPA will take 

action on the visibility element in a 

separate action. None of the findings 

and conclusions in this notice, 

accordingly, relate to EPA’s analysis of 

interference with another state’s 

required measures to protect visibility. 

EPA will also take action on the portion 

of Idaho’s SIP that addresses the 2006 

PM2.5 NAAQS 1 in a separate action. 

II. What is the background for this 

action? 

On July 18, 1997, EPA promulgated 

new standards for 8-hour ozone and fine 

particulate matter (PM2.5). This action is 

being taken in response to the 

promulgation of the 1997 8-hour ozone 

NAAQS and 1997 PM2.5 NAAQS. This 

action does not address the 

requirements of the 2006 24-hour PM2.5

NAAQS or the 2008 8-hour ozone 

NAAQS; those standards will be 

addressed in a future action. 

Section 110(a)(1) of the CAA requires 

states to submit SIPs to address a new 

or revised NAAQS within three years 

after promulgation of such standards, or 

within such shorter period as EPA may 

prescribe. Section 110(a)(2) lists the 

elements that such new SIPs must 

address, as applicable, including section 

110(a)(2)(D)(i) which pertains to 

interstate transport of certain emissions. 

On August 15, 2006, EPA issued its 

‘‘Guidance for State Implementation 

Plan (SIP) Submissions to Meet Current 

Outstanding Obligations Under Section 

110(a)(2)(D)(i) for the 8-hour ozone and 

PM2.5 National Ambient Air Quality 

Standards’’ (2006 Guidance) for SIP 

submissions that states should use to 

address the requirements of section 

110(a)(2)(D)(i). EPA developed this 

guidance to make recommendations to 

states for making submissions to meet 

the requirements of section 110(a)(2)(D) 

for the 1997 8-hour ozone standards and 

1997 PM2.5 standards. 

On June 28, 2010, we received a SIP 

revision from the State of Idaho to 

address the requirements of section 

110(a)(2)(D)(i) for both the 1997 8-hour 

ozone NAAQS and 1997 PM2.5 NAAQS. 

The state based its submittal on EPA’s 

2006 Guidance. As explained in the 

2006 Guidance, the ‘‘good neighbor’’ 

provisions in section 110(a)(2)(D)(i) 

require each state to submit a SIP that 

contains adequate provisions to prohibit 

emissions from sources within that state 

from adversely affecting another state in 

the ways contemplated in the statute. 

Section 110(a)(2)(D)(i) identifies four 

distinct elements related to the 

evaluation of impacts of interstate 

transport of air pollutants. In this 

rulemaking EPA is addressing the first 

three elements: (1) Significant 

contribution to nonattainment of these 

NAAQS in any other state, (2) 

interference with maintenance of these 

NAAQS by any other state, and (3) 

interference with any other state’s 

required measures to prevent significant 

deterioration (PSD) of its air quality 

with respect to these NAAQS. Idaho 

asserted in its SIP submission that its 

current SIP is adequate to prevent such 

contribution and interference, and thus 

no additional controls or revisions are 

needed with respect to the 1997 8-hour 

ozone NAAQS and 1997 PM2.5 NAAQS. 

On September 13, 2010, EPA 

published a proposal to approve the 

portion of Idaho’s SIP submission that 

addresses the three elements of CAA 

section 110(a)(2)(D) for both the 1997 8- 

hour ozone NAAQS and 1997 PM2.5

NAAQS: (1) Significant contribution to 

nonattainment of these NAAQS in any 

other state, (2) interference with 

maintenance of these NAAQS by any 

other state, and (3) interference with any 

other state’s required measures to 

prevent significant deterioration (PSD) 

of its air quality with respect to these 

NAAQS (75 FR 55494). EPA finds that 

Idaho’s Interstate Transport SIP 

provisions addressing elements (1), (2), 

and (3) of section 110(a)(2)(D)(i) are 

consistent with the requirements of the 

CAA. 

III. Response to Comments 

EPA received one letter from 

WildEarth Guardians (WG) commenting 

on several aspects of EPA’s proposed 

approval of the Idaho Interstate 

Transport SIP. These comments 

addressed the ‘‘significant contribution 

to nonattainment,’’ and ‘‘interfere with 

maintenance,’’ elements of the SIP for 

the 1997 8-hour ozone and 1997 PM2.5

NAAQS. WG also alleged in its 

comments that EPA failed to comply 

with the requirements of CAA Section 

110(l) with respect to the attainment 

and maintenance of the current NAAQS. 

No comments were received that 

specifically addressed EPA’s proposed 

approval of the ‘‘interfere with any other 

state’s required measures to prevent 

significant deterioration’’ elements of 

the SIP for the 1997 8-hour ozone and 

1997 PM2.5 NAAQS. In this section EPA 

summarizes and responds to the 

significant adverse comments submitted 

by the commenter. 

A. Comments Relating to the 

‘‘Significant Contribution to 

Nonattainment’’ Element 

Comment No. 1—WG argued that 

Idaho and EPA did not appropriately 

assess impacts to nonattainment in 

downwind states. According to WG, 

Idaho failed to assess significance of 

downwind impacts in accordance with 

EPA guidance and precedent. The 

commenter identified statements by 

EPA in the context of the 1998 NOX SIP 

Call as the applicable guidance for this 

purpose. WG asserts that, based on the 

precedent of the NOX SIP Call, the 

following issues need to be addressed in 

determining whether or not an area is 

significantly contributing to 

nonattainment in downwind states: (a) 

The overall nature of the ozone 

problem; (b) the extent of downwind 

nonattainment problems to which the 

upwind state’s emissions are linked; (c) 

the ambient impact of the emissions 

from the upwind state’s sources on the 

downwind nonattainment problems; 

and (d) the availability of highly costeffective control measures for upwind 

emissions. 63 FR 57356, 57376 (October 

27, 1998). 

EPA Response—EPA disagrees with 

the commenter’s conclusions regarding 

the relevant guidance and standards 

necessary to determine whether or not 

a state’s emissions contribute 

significantly to nonattainment in 

another state. Section 110(a)(2)(D) does 

not explicitly specify how states or EPA 

should evaluate the existence of, or 

extent of, interstate transport and 

whether such transport is of sufficient 

magnitude to constitute ‘‘significant 

contribution to nonattainment’’ as a 

regulatory matter. The statutory 

language is ambiguous on its face and 

EPA must reasonably interpret that 

language and its application to factual 

situations before the Agency. 

The NOX SIP Call is one rulemaking 

in which EPA evaluated the existence 

of, and extent of, interstate transport. In 

that action, EPA developed an approach 

that allowed the Agency to evaluate 

whether there was significant 

contribution to ozone nonattainment 

across an entire region that was 

comprised of many states. That 


srobinson on DSKHWCL6B1PROD with RULES
Federal Register / Vol. 75, No. 227 / Friday, November 26, 2010 / Rules and Regulations 72707 

2Memorandum from William T. Harnett entitled 

Guidance for State Implementation Plan (SIP) 

Submissions to Meet Current Outstanding 

Obligations Under Section 110(a)(2)(D)(i) for the 8- 

hour Ozone and PM2.5 National Ambient Air 

Quality Standards (Aug. 15, 2006) (‘‘2006 

Guidance’’), p. 3. An electronic copy is available for 

review at the regulations.gov Web site as Document 

ID No. EPA–R10–OAR–2010–0669–0005. 

3 2006 Guidance at 3. 

4 Id. 

5 In this action, ‘‘CAIR’’ refers to the final rule 

published in the May 12, 2005, Federal Register 

and entitled ‘‘Rule to Reduce Interstate Transport of 

Fine Particulate Matter and Ozone (Clean Air 

Interstate Rule); Revisions to Acid Rain Program; 

Revisions to NOX SIP Call; Final Rule.’’ 70 FR 

25162. 

6 2006 Guidance at 5. 

7 Id. 

approach included regional scale 

modeling and other technical analyses 

that EPA deemed useful to evaluate the 

issue of interstate transport on that 

geographic scale and for the facts and 

circumstances at issue in that 

rulemaking. EPA does not agree, 

however, that the approach used in the 

NOX SIP Call is necessarily the only 

way that states or EPA may evaluate the 

existence of, and extent of, interstate 

transport in all situations, and 

especially in situations where the state 

and EPA are evaluating the question on 

a state by state basis, and in situations 

where there is not evidence of 

widespread interstate transport. 

The commenter failed to acknowledge 

that EPA issued specific guidance 

making recommendations to states 

about how to address section 

110(a)(2)(D) in SIP submissions for the 

8-hour ozone and PM2.5 NAAQS. EPA 

issued this guidance document, entitled 

‘‘Guidance for State Implementation 

Plan (SIP) Submissions to Meet Current 

Outstanding Obligations Under Section 

110(a)(2)(D)(i) for the 8–Hour Ozone and 

PM2.5 National Ambient Air Quality 

Standards’’ on August 15, 2006 (‘‘2006 

Guidance’’).2 The 2006 Guidance 

postdated the NOX SIP Call, and was 

developed by EPA specifically to 

address SIP submissions for the 1997 8- 

hour ozone and PM2.5 NAAQS. In EPA’s 

proposal, this Guidance was identified 

by the Agency as applicable to the 

analysis before it. 

In the 2006 Guidance, EPA explicitly 

stated its view that the ‘‘precise nature 

and contents of such a submission [are] 

not stipulated in the statute’’ and that 

the contents of the SIP submission ‘‘may 

vary depending upon the facts and 

circumstances related to the specific 

NAAQS.’’ 3 Moreover, within that 

Guidance, EPA expressed its view that 

‘‘the data and analytical tools available’’ 

at the time of the SIP submission 

‘‘necessarily [affect] * * * the content of 

the required submission.’’ 4 To that end, 

EPA specifically recommended that 

states located within the geographic 

region covered by the ‘‘Clean Air 

Interstate Rule’’ (CAIR) 5 comply with 

section 110(a)(2)(D) for the 1997 8-hour 

ozone and PM2.5 NAAQS by complying 

with CAIR itself. For states outside the 

CAIR rule region, however, EPA 

recommended that states develop their 

SIP submissions for section 110(a)(2)(D) 

considering relevant information. 

EPA explicitly recommended that 

relevant information for section 

110(a)(2)(D) submissions addressing 

significant contribution to 

nonattainment ‘‘might include, but is 

not limited to, information concerning 

emissions in the state, meteorological 

conditions in the state, the distance to 

the nearest nonattainment area in 

another state, reliance on modeling 

conducted by EPA in determining that 

such state should not be included 

within the ambit of the CAIR, or such 

other information as the state considers 

probative on the issue of significant 

contribution.’’ 6 In addition, EPA 

recommended that states might elect to 

evaluate significant contribution to 

nonattainment using relevant 

considerations comparable to those used 

by EPA in CAIR, including evaluating 

impacts as of an appropriate year and in 

light of the cost of control to mitigate 

emissions that resulted in significant 

contribution.7

WG did not acknowledge or discuss 

EPA’s 2006 Guidance for section 

110(a)(2)(D) SIP submissions for the 

1997 8-hour ozone and PM2.5 NAAQS, 

even though it was specifically 

identified and applied in EPA’s 

proposal. EPA believes that the Idaho 

submission and EPA’s evaluation of it 

were consistent with EPA’s 2006 

Guidance for the 1997 8-hour ozone and 

PM2.5 NAAQS. For example, as 

discussed in the proposal notice, the 

state and EPA considered information 

such as monitoring data in Idaho and 

downwind states, geographical and 

meteorological information, and 

technical studies of the nature and 

sources of nonattainment problems in 

various downwind states. These are 

among the types of information that 

EPA recommended and that EPA 

considers relevant under the 

circumstances of this action. Thus, EPA 

has concluded that the state’s 

submission meets the requirements of 

section 110(a)(2)(D) and that EPA’s 

evaluation of the state’s SIP is consistent 

with the applicable 2006 Guidance and 

the Act. 

Finally, EPA notes that the 

considerations in the 2006 Guidance are 

consistent with the concepts that WG 

identified as applicable from the NOX

SIP Call: (a) The overall nature of the 

problem; (b) the extent of the downwind 

nonattainment problems to which the 

upwind state’s emissions are linked; (c) 

the ambient impact of the emissions 

from the upwind state’s sources on the 

downwind nonattainment problems; 

and (d) the availability of highly costeffective control measures for upwind 

emissions. These factors were taken into 

account in EPA’s analysis of the Idaho 

SIP with the exception of consideration 

of the costs of controls for sources. EPA 

did not evaluate those costs because the 

available evidence indicated that there 

is very little contribution from 

emissions from Idaho sources to 

nonattainment in other states. 

Comment No. 2 —WG objected to 

EPA’s proposed approval on the 

grounds that Idaho and EPA failed to 

adequately analyze and assess the 

contribution from Idaho’s emissions to 

downwind states, and did not conduct 

an actual assessment of the significance 

of any such contribution or impacts. 

EPA Response—EPA disagrees with 

WG’s characterization of Idaho’s and 

EPA’s demonstration and analysis. WG 

again assumes that section 110(a)(2)(D) 

explicitly demands the type of modeling 

analysis that the commenter advocates 

throughout its comments. WG contends 

that any analytical approach that is not 

identical to the approach used in the 

NOX SIP Call is impermissible. In 

addition, WG failed to acknowledge that 

in other actions under section 

110(a)(2)(D), EPA has used a variety of 

analytical approaches, short of 

modeling, to evaluate whether a specific 

state is significantly contributing to 

violations of the NAAQS in another 

state (e.g., the west coast states that EPA 

concluded should not be part of the 

geographic region of the CAIR rule 

based upon qualitative factors, and not 

by the zero out modeling EPA deemed 

necessary for some other states). 

EPA’s analysis took into account 

meteorological conditions, monitoring 

data, distance, topography and other 

quantitative and qualitative forms of 

available information to evaluate and 

identify a potentially significant 

contribution from Idaho’s emissions to 

nonattainment of the 1997 8-hour ozone 

and 1997 PM2.5 NAAQS in other states. 

As noted in EPA’s proposal, no single 

piece of information informing this 

analysis is, by itself, dispositive of the 

issue. Instead, the total weight of all the 

evidence taken together was used to 

evaluate significant contributions to 

violations of the 1997 8-hour ozone or 

1997 PM2.5 NAAQS in another state. 

Based on the available information, 


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72708 Federal Register / Vol. 75, No. 227 / Friday, November 26, 2010 / Rules and Regulations 

8 Michigan v. U.S. EPA, 213 F.3d 663, 674–681 

(DC Cir. 2000); North Carolina v. EPA, 531 F.3d 

896, 913–916 (D.C. Cir. 2008) (upholding EPA 

approach to determining threshold despite 

remanding other aspects of CAIR). 

9 2006 Guidance, p. 5. 

10 ‘‘Based on this approach, we predicted that in 

the absence of additional control measures, 47 

counties with air quality monitors [emphasis ours] 

would violate the 8-hour ozone NAAQS in 2010. 

***’’ From the CAIR proposed rule of January 30, 

2004 (69 FR 4566, 4581). The NOX SIP call 

proposed rule action reads: ‘‘* * * For current 

nonattainment areas, EPA used air quality data for 

the period 1993 through 1995 to determine which 

counties are violating the 1-hour and/or 8-hour 

NAAQS. These are the most recent 3 years of fully 

quality assured data which were available in time 

for this assessment,’’ 62 FR 60336. 

using a combination of quantitative data 

and qualitative analyses, we concluded 

emissions from Idaho do not contribute 

significantly to downwind ozone 

nonattainment. Thus, contrary to WG’s 

assertion, EPA did perform an analysis 

and assessment that formed a reasonable 

basis for the conclusion that emissions 

from Idaho do not contribute 

significantly to downwind ozone and 

PM2.5 nonattainment, using a 

combination of quantitative data and 

qualitative analyses. EPA does not agree 

that the type of analysis advocated by 

WG is required by the statute and is 

necessary to support a rational 

determination in this instance. 

Comment No. 3—WG objected to 

EPA’s proposed approval because EPA’s 

assessment of impacts on downwind 

states was based upon monitoring data 

in those states, and WG alleges that this 

is not an adequate means of evaluating 

significant contribution to 

nonattainment. WG is concerned that 

the impacts of Idaho’s emissions in 

areas without monitors were not 

assessed and that EPA only assessed 

‘‘impacts to areas that are designated as 

nonattainment or with monitors that 

have recorded violations of the ozone 

and PM2.5 NAAQS.’’ WG argued that this 

reliance on monitoring data is 

inconsistent with both section 

110(a)(2)(D) and with EPA’s guidance 

provided in the NOX SIP Call. In 

support of its objections, WG quoted 

statements from the NOX SIP Call 

proposal in which EPA discussed its 

proposed interpretation of the statutory 

phrase ‘‘contribute significantly to 

nonattainment’’: 

‘‘The EPA proposes to interpret this term to 

refer to air quality and not to be limited to 

currently-designated nonattainment areas. 

Section 110(a)(2)(D) does not refer to 

‘nonattainment areas,’ which is a phrase that 

EPA interprets to refer to areas that are 

designated nonattainment under section 107 

(section 107(d)(1)(A)(I)).’’ 

According to WG, this statement, and 

similar ones in the context of the final 

NOX SIP Call rulemaking, establish that 

states and EPA cannot utilize 

monitoring data to evaluate the 

existence of, and extent of, interstate 

transport. Furthermore, WG interprets 

the reference to ‘‘air quality’’ in these 

statements to support its contention, 

amplified in later comments, that EPA 

must evaluate significant contribution 

in areas in which there is no monitored 

nonattainment. 

EPA Response—EPA disagrees with 

WG’s arguments. First, WG 

misunderstands the point that EPA was 

making in quoted statement from the 

NOX SIP Call proposal (and that EPA 

has subsequently made in the context of 

CAIR). When EPA stated that it would 

evaluate impacts on air quality in 

downwind states, independent of the 

current formal ‘‘designation’’ of such 

downwind states, it was not referring to 

air quality in the absence of monitor 

data. EPA’s point was that it was 

inappropriate to wait for either initial 

designations of nonattainment for a new 

NAAQS under section 107(d)(1), or for 

a redesignation to nonattainment for an 

existing NAAQS under section 

107(d)(3), before EPA could assess 

whether there is significant contribution 

to nonattainment of a NAAQS in 

another state. 

For example, in the case of initial 

designations, section 107(d) 

contemplates a process and timeline for 

initial designations that could well 

extend for two or three years following 

the promulgation of a new or revised 

NAAQS. By contrast, section 110(a)(1) 

requires states to make SIP submissions 

that address section 110(a)(2)(D) and 

interstate transport ‘‘within 3 years or 

such shorter period as the Administrator 

may prescribe’’ of EPA’s promulgation of 

a new or revised NAAQS. This schedule 

does not support a reading of section 

110(a)(2)(D) that is dependent upon 

formal designations having occurred 

first. This is a key reason why EPA 

determined that it was appropriate to 

evaluate interstate transport based upon 

monitor data, not designation status, in 

the CAIR rulemaking and in the matter 

at hand. 

WG’s misunderstanding of EPA’s 

statement concerning designation status 

evidently caused WG to believe that 

EPA’s assessment of interstate transport 

in the NOX SIP Call was not limited to 

evaluation of downwind areas with 

monitors. This is simply incorrect. In 

both the NOX SIP Call and CAIR, EPA 

evaluated significant contribution to 

nonattainment as measured or predicted 

at monitors. For example, in the 

technical analysis for the NOX SIP Call, 

EPA specifically evaluated the impacts 

of emissions from upwind states on 

monitors located in downwind states. 

The NOX SIP Call did not evaluate 

impacts at points without monitors, nor 

did the CAIR rulemaking. EPA believes 

that this approach to evaluating 

significant contribution is correct under 

section 110(a)(2)(D), and EPA’s general 

approach to this threshold 

determination has not been disturbed by 

the courts.8

Finally, EPA disagrees with WG’s 

argument that the assessment of 

significant contribution to downwind 

nonattainment must include evaluation 

of impacts on non-monitored areas. 

First, neither section 110(a)(2)(D)(i)(I) 

provisions, nor the 2006 Guidance 

support WG’s position, as neither refers 

to any requirement or recommendation 

to assess air quality in non-monitored 

areas.9 The same focus on monitored 

data as a means of assessing interstate 

transport is found in the NOX SIP Call 

and in CAIR. An initial step in both the 

NOX SIP Call and CAIR was the 

identification of areas with current 

monitored violations of the ozone and/ 

or PM2.5 NAAQS.10 The subsequent 

modeling analyses for NAAQS 

violations in future years (2007 for the 

SIP Call and 2010 for CAIR) likewise 

evaluated future violations at monitors 

in areas identified in the initial step. 

Thus, WG is simply in error that EPA 

has not previously evaluated the 

presence and extent of interstate 

transport under section 110(a)(2)(D) by 

focusing on monitoring data. Indeed, 

such monitoring data was at the core of 

both of these efforts. In neither of these 

rulemakings did EPA evaluate 

significant contribution to 

nonattainment in areas in which there 

was no monitor. Reliance on monitoring 

data is reasonable and appropriate, 

because data from a properly placed 

federal reference method monitor is the 

way in which EPA ascertains that there 

is a violation of the 1997 8-hour ozone 

or PM2.5 NAAQS in a particular area. 

Put another way, in order for there to be 

significant contribution to 

nonattainment for the 1997 8-hour 

ozone or PM2.5 NAAQS, there must be 

a monitor with data showing a violation 

of that NAAQS. EPA concludes that by 

considering data from monitored areas, 

its assessment of whether emissions 

from Idaho contribute significantly to 

ozone or PM2.5 nonattainment in 

downwind states is consistent with the 

2006 Guidance, and with the approach 

used by both the CAIR rule and the NOX

SIP Call. 

Comment No. 4—In support of its 

comments that EPA should assess 

significant contribution to 

nonattainment in nonmonitored areas, 


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Federal Register / Vol. 75, No. 227 / Friday, November 26, 2010 / Rules and Regulations 72709 

11Stoeckenius, T.E., C.A. Emery, T.P. Shah, J.R. 

Johnson, L.K. Parker, A.K. Pollack, 2009. ‘‘Air 

Quality Modeling Study for the Four Corners 

Region.’’ Prepared for the New Mexico Environment 

Department, Air Quality Bureau, Santa Fe, NM, by 

ENVIRON International Corporation, Novato, CA. 

12The southwestern area referred to by the 

commenter includes portions of Washington, Iron, 

Kane, and Garfield Counties. 

13See ‘‘UBAQS,’’ pages 4–27 to 4–29. 

14EPA. 2007. Guidance on the Use of Models and 

other Analyses for Demonstrating Attainment of Air 

Quality Goals for Ozone, PM2.5 and Regional Haze. 

Office of Air Quality Planning and Standards, Air 

Modeling Group. Research Triangle Park, North 

Carolina (http://www.epa.gov/scram001/guidance/ 

guide/final-03-pm-rh-guidance.pdf). 

15 DVC × RRF = DVF. 

WG argued that existing modeling 

performed by another organization 

‘‘indicates that large areas of neighboring 

states will likely violate the ozone 

NAAQS.’’ According to WG, these likely 

‘‘violations’’ of the ozone NAAQS were 

predicted for the year 2018, as reflected 

in a slide from a July 30, 2008, 

presentation before the Western 

Regional Air Partnership (‘‘Review of 

Ozone Performance in WRAP Modeling 

and Relevant to Future Regional Ozone 

Planning’’). WG asserted that: ‘‘Slide 28 

of this presentation displays projected 

4th highest 8-hour ozone reading for 

2018 and indicates that air quality in 

areas throughout Utah, Wyoming, 

Colorado, and Nevada will exceed and/ 

or violate the 1997 ozone NAAQS. 

***’’ In short, WG argues that 

modeling performed by the WRAP 

establishes that there will be violations 

of the 1997 8-hour ozone NAAQS in 

2018 in non-monitored areas in these 

western states. 

EPA Response—EPA disagrees with 

this comment on several grounds. First, 

as explained in response to other 

comments, EPA does not agree that it is 

appropriate to evaluate significant 

contribution to nonattainment for the 

1997 8-hour ozone NAAQS by modeling 

ambient levels in areas where there is 

no monitor to provide data to establish 

a violation of the NAAQS in question. 

Section 110(a)(2)(D) does not require 

such an approach, EPA has not taken 

this approach in the NOX SIP Call or 

other rulemakings under section 

110(a)(2)(D), and EPA’s prior analytical 

approach has not been disturbed by the 

courts. 

Second, WG’s own description of the 

ozone concentrations predicted for the 

year 2018 as projecting ‘‘violations’’ of 

the ozone NAAQS is inaccurate. Within 

the same sentence, quoted above, slide 

28 is described as displaying the 

projected 4th max ozone reading for the 

year 2018, and as indicating that ‘‘* * * 

air quality * * * will exceed or violate 

[our emphasis] the 1997 ozone 

NAAQS.’’ By definition, a one year 

value of the 4th max above the NAAQS 

only constitutes an exceedance of the 

NAAQS; to constitute a violation of the 

1997 8-hour ozone NAAQS, the 

standard must be exceeded for three 

consecutive years at the same monitor. 

Thus, even if the WRAP presentation 

submitted by WG were technically 

sound, the conclusion drawn from it by 

WG is inaccurate and does not support 

its claim of projected violations of the 

NAAQS in surrounding states. 

EPA has also reviewed the WRAP 

presentation submitted by WG and 

believes that there was a substantial 

error in the WRAP modeling software 

that led to an overestimation of ground 

level ozone concentrations. A recent 

study conducted by Environ for the 

Four Corners Air Quality Task Force 

(FCAQTF; Stoeckenius et al., 2009) has 

demonstrated that excessive vertical 

transport in the CMAQ and CAMx 

models over high terrain was 

responsible for overestimated ground 

level ozone concentrations due to 

downward transport of stratospheric 

ozone.11 Environ has developed revised 

vertical velocity algorithms in a new 

version of CAMx that eliminated the 

excessive downward transport of ozone 

from the top layers of the model. This 

revised version of the model is now 

being used in a number of applications 

throughout high terrain areas in the 

West. In conclusion, EPA believes that 

this key inadequacy of the WRAP 

model, noted above, makes it 

inappropriate support for WG’s 

concerns about large expanses of 8-hour 

ozone nonattainment areas projected for 

2018 in areas without monitors. 

Comment No. 5—As additional 

support for its assertion that EPA should 

require modeling to assess ambient 

levels in unmonitored portions of other 

states, WG relied on an additional study 

entitled the ‘‘Uinta Basin Air Quality 

Study (UBAQS).’’ The commenter 

argued that the UBAQS study further 

supports its concern that limiting the 

evaluation of downwind impacts only to 

areas with monitors fails to assess ozone 

nonattainment in non-monitored areas. 

According to the commenter, UBAQS 

modeling results show that: (a) The 

Wasatch front region is currently 

exceeding and will exceed in 2012 the 

1997 8-hour ozone NAAQS, and (b) 

based on 2005 meteorological data, 

portions of the four counties in the 

southwest corner of Utah are also 

currently in nonattainment and will be 

in nonattainment in 2012.12

EPA Response—As noted above, EPA 

does not agree that it is appropriate to 

assess significant contribution to 

nonattainment for the 1997 8-hour 

ozone NAAQS in the way advocated by 

WG. Even taking the UBAQS modeling 

results at their face value, however, EPA 

does not agree that the 8-hour ozone 

nonattainment (current and projected) 

in the Wasatch Front Range area 

supports the commenter’s concerns 

about the need to evaluate the 

possibility of significant contribution to 

nonattainment in non-monitored areas. 

EPA sees several problems with the 

commenter’s interpretation of the 

UBAQS analysis results for counties in 

Utah’s southwestern corner: ‘‘based on 

2005 meteorological data, portions of 

Washington, Iron, Kane, and Garfield 

Counties are also in nonattainment and 

will be in nonattainment in 2012.’’ 

First, WG’s interpretation of the 

predicted ozone concentrations shown 

in Figures 4–3a and 4–3b (pages 5 and 

6 of the comment letter) is inaccurate. 

A close review of the legend in these 

figures indicates that the highest ozone 

concentrations predicted by the model 

for portions of the counties noted above 

are somewhere between 81.00 and 85.99 

ppb, but a specific concentration is not 

provided. If the ozone concentration is 

actually predicted to be smaller than or 

equal to 84.9 ppb, then the area is 

attaining; if it is predicted as greater 

than 84.9 ppb then it is not attaining. 

This means that current and predicted 

design values for the southwestern Utah 

area identified in Figures 4–3a and 4– 

3b could both be in attainment or both 

in nonattainment, or one of them in 

attainment and the other in 

nonattainment, for the 1997 8-hour 

ozone NAAQS. 

Second, even if the design values 

predicted for these unmonitored areas 

were at the top of the 81.00–85.99 ppb 

range, their reliability would remain 

questionable. The UBAQS itself 

identifies and illustrates major 

shortcomings of its modeling analysis, 

only to neglect assessing the impact of 

these shortcomings on the modeling 

results.13 The study deviates in at least 

two significant ways from EPA’s 2007 

guidance on SIP modeling.14 One issue 

is the UBAQS modeling reliance on 

fewer than the five years of data 

recommended by EPA to generate a 

current 8-hour ozone design value 

(DVC). UBAQS relaxed this requirement 

so that sites with as little as 1 year of 

data were included as DVCs in the 

analysis. The other issue is the 

computation of the relative responsive 

factor (RRF), which directly affects the 

modeling’s future design value (DVF).15

Again due to unavailability of data 

satisfying EPA’s recommendation that 

the RRF be based on a minimum of five 

days of ozone concentrations above 85 


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72710 Federal Register / Vol. 75, No. 227 / Friday, November 26, 2010 / Rules and Regulations 

16See UBAQS, p. 4–28. 

17EPA most recently reviewed the adequacy of 

the Idaho monitoring network on October 14, 2010. 

See letter dated October 14, 2010 from Debra 

Suzuki, EPA Region 10, to Dave Broker, IDEQ. 

18WG’s October 13, 2010, comment letter, pp. 9– 

10. The referenced letters have been included in the 

docket for this action. 

ppb, UBAQS modeling uses RRFs based 

on one or more days of ozone 

concentrations above 70 ppb.16 EPA 

concludes that the modeling analysis 

results used by the WG are unreliable 

for projecting non-attainment status and 

therefore do not support its comments. 

Comment No. 6—In support of its 

arguments that EPA should not limit 

assessment of significant contribution to 

nonattainment through evaluation of 

impacts at monitors, but include, 

through a modeling analysis, impacts 

where there are no such monitors, the 

commenter cited a past statement by 

EPA to the effect that the monitor 

network in the western United States 

needs to be expanded. The quoted 

statements included EPA’s observation 

that ‘‘[v]irtually all States east of the 

Mississippi River have at least two to 

four non-urban O3 monitors, while 

many large mid-western and western 

States have one or no non-urban 

monitors.’’ 74 FR 34,525 (July 16, 2009). 

From this statement, the commenter 

argues that it is not appropriate for EPA 

to limit the evaluation of significant 

contribution to nonattainment in other 

states to a consideration of monitor data 

instead of modeling ambient pollutant 

levels because there are states with few 

or no non-urban monitors surrounding 

Idaho. 

EPA Response—EPA acknowledges 

that WG’s observation that there are 

relatively few monitors in the western 

states, and that relatively few monitors 

are currently located in non-urban areas 

of western states, is factually correct. 

However, the commenter failed to note 

that the quoted statement from EPA 

concerning the adequacy of western 

monitors came from the Agency’s July 

16, 2009, proposed rulemaking entitled 

‘‘Ambient Ozone Monitoring 

Regulations: Revisions to Network 

Design Requirements.’’ This statement 

was taken out of context, because EPA 

was in that proposal referring to changes 

in state monitoring networks that it 

anticipates will be necessary in order to 

implement not the 1997 8-hour ozone 

NAAQS that is the subject of this 

rulemaking, but rather the 2008 ozone 

NAAQS for which there are concerns 

that there will be a need to evaluate 

ambient levels in previously 

unmonitored areas of the western 

United States. The fact that additional 

monitors may be necessary in the future 

for the newer ozone NAAQS does not 

automatically mean that the existing 

ozone monitoring networks are 

insufficient for the 1997 8-hour ozone 

NAAQS, as the commenter implies. 

Indeed, states submit annual monitoring 

network plans to EPA and EPA 

evaluates these to insure that they meet 

the applicable requirements. For 

example, Idaho itself submits just such 

a report on an annual basis, and EPA 

reviews it for adequacy.17 All other 

states submit comparable reports. 

Comment No. 7—WG objected to 

EPA’s proposed approval of the Idaho 

SIP submission because neither Idaho 

nor EPA performed a specific modeling 

analysis to assure that emissions from 

Idaho sources do not significantly 

contribute to nonattainment in 

downwind states. According to the 

commenter, EPA’s decision to use a 

qualitative approach to determine 

whether emissions from Idaho 

contribute significantly to downwind 

nonattainment is not consistent with its 

own preparation of a regional model to 

evaluate such impacts from other states 

as part of CAIR. 

EPA Response—EPA disagrees with 

WG’s proposition that only modeling 

can establish whether or not there is 

significant contribution from one state 

to the nonattainment of another. First, 

as noted above, EPA does not believe 

that section 110(a)(2)(D) requires a 

modeling analysis in all instances. 

While modeling can be useful, EPA 

believes that other forms of analysis can 

be sufficient to evaluate whether or not 

there is significant contribution to 

nonattainment. For this reason, EPA’s 

2006 Guidance recommended other 

forms of information that states may rely 

upon as part of their section 110(a)(2)(D) 

submissions for the 1997 8-hour ozone 

and 1997 PM2.5 NAAQS. EPA has 

concluded that its qualitative approach 

to the assessment of significant 

contribution to downwind ozone and 

PM2.5 nonattainment is consistent with 

EPA’s 2006 Guidance. 

Second, EPA notes that WG’s 

comment also reflects a 

misunderstanding of the approach EPA 

used in the remanded CAIR. In CAIR, 

EPA determined that several factors 

provided a reasonable basis to exclude 

certain western states from the ambit of 

that rulemaking: ‘‘[i]n analyzing 

significant contribution to 

nonattainment, we determined it was 

reasonable to exclude the Western U.S., 

including the states of Washington, 

Idaho, Oregon, California, Nevada, Utah, 

and Arizona from further analysis due 

to geography, meteorology, and 

topography. Based on these factors we 

concluded that the PM2.5 and 8-hour 

ozone nonattainment problems are not 

likely to be affected significantly by 

pollution transported across these 

States’ boundaries. * * *’’ 69 FR 4581 

(January 30, 2004). 

EPA has taken a similar approach to 

assess whether Idaho contributes 

significantly to violations of the 1997 8- 

hour ozone and PM2.5 NAAQS in 

downwind states. In the proposed 

action, EPA explained several forms of 

substantive and technically valid 

evidence that led to the conclusion that 

emissions from Idaho sources do not 

contribute significantly to 

nonattainment, in accordance with the 

requirement of Section 110(a)(2)(D). 

Comment No. 8—In further support of 

its argument that EPA must use 

modeling to evaluate whether there is 

significant contribution to 

nonattainment under section 

110(a)(2)(D), WG noted that EPA itself 

asks other agencies to perform such 

modeling in other contexts. As 

examples, the commenter cited four 

instances in which EPA commented on 

actions by other agencies and 

recommended the use of a modeling 

analysis to assess ozone impacts prior to 

authorizing oil and gas development 

projects. As supporting material, the 

comment includes quotations from and 

references to EPA letters to Federal 

Agencies on assessing impacts of oil and 

gas development projects.18 WG 

questioned why EPA’s recommendation 

for such an approach in its comments to 

other Federal Agencies did not result in 

its use of the same approach to evaluate 

the impacts from Idaho emissions and to 

insure compliance with Section 

110(a)(2)(D)(i)(I). The commenter 

reasoned that the emissions that would 

result from the actions at issue in the 

other agency decisions, such as selected 

oil and gas drilling projects, would be 

of less magnitude and importance than 

the statewide emissions at issue in an 

evaluation under section 110(a)(2)(D). 

EPA Response—As explained above, 

EPA disagrees with WG’s fundamental 

argument that modeling is required to 

evaluate significant contribution to 

nonattainment, whether by section 

110(a)(2)(D), by EPA guidance, or by 

past EPA precedent. EPA’s applicable 

guidance made recommendations as to 

different approaches that can satisfy the 

interstate transport requirements for 

significant contribution to 

nonattainment in other states. Even 

EPA’s own CAIR analysis relied on a 

combination of qualitative and 

quantitative analyses, as explained 

above. As indicated in our response to 


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Federal Register / Vol. 75, No. 227 / Friday, November 26, 2010 / Rules and Regulations 72711 

19 69 FR 4581, January 30, 2004. 

20See: 69 FR 4581, January 30, 2004. 

21 75 FR 55494, September 13, 2010. 

Comment No. 7, the CAIR analysis 

excluded the western states based on a 

qualitative assessment of the regions 

topography, geography and 

meteorology.19

EPA believes that the commenter’s 

references to EPA statements 

commenting on the actions of other 

agencies are inapposite. As WG is 

aware, those comments were made in 

the context of the evaluation of the 

impacts of various federal actions 

pursuant to the National Environmental 

Policy Act (NEPA), not the Clean Air 

Act. As explained above, section 

110(a)(2)(D) governs this particular 

decision-making process, and EPA does 

not agree that modeling is always 

required to support the evaluation. EPA 

itself has relied on qualitative evidence 

for this purpose when the relevant 

record provides evidence sufficient to 

reach a reasoned determination. 

Comment No. 9—In further support of 

its argument that EPA should always 

require modeling to evaluate significant 

contribution to nonattainment, WG 

referred to EPA regulations governing 

nonattainment SIPs. The commenter 

referenced 40 CFR 51.112(a)(1), which 

states that: ‘‘[t]he adequacy of a control 

strategy shall be demonstrated by means 

of applicable air quality models, data 

bases, and other requirements specified 

in appendix W of [Part 51] (Guideline 

on Air Quality Models).’’ The 

commenter argued that this regulation 

supports its position that modeling is 

required to satisfy the significant 

contribution element of 110(a)(2)(D). 

EPA Response—EPA disagrees with 

this comment. The cited language 

addresses the control strategy 

requirements when the necessity of 

controls has already been established. 

The cited provision requires a modeling 

analysis to demonstrate the adequacy of 

the control strategy developed to 

achieve the reductions necessary to 

prevent an area’s air quality from 

continuing to violate the NAAQS. EPA’s 

determination that emissions from 

Idaho do not contribute significantly to 

nonattainment for the 1997 8-hour 

ozone standard in any other states 

eliminates the need for a control 

strategy aimed at satisfying the section 

110(a)(2)(D) requirements. The 

provision cited by the commenter, 

therefore, is inapplicable in this context. 

Moreover, EPA interprets the language 

at 40 CFR 51.112(a): ‘‘[e]ach plan must 

demonstrate that the measures, rules, 

and regulations contained in it are 

adequate to provide for the timely 

attainment and maintenance of the 

national standard that it implements,’’ to 

refer to modeling for attainment 

demonstrations, an integral part of 

nonattainment area SIPs under 

subchapter I, part D of the CAA. This 

interpretation was upheld by the Sixth 

Circuit Court of Appeals. Wall v. U.S. 

EPA, 265 F.3d 426, 436 (6th Cir. 2001). 

Thus, the commenter’s cited regulation 

is not relevant to EPA’s technical 

analysis assessing whether emissions 

from Idaho contribute significantly to 

nonattainment in any other states under 

section 110(a)(2)(D). 

Comment No. 10—WG referenced 

several modeling analyses of emissions 

in the western United States which it 

contends renders EPA’s analysis 

inadequate. The commenter 

‘‘challenged’’ EPA to prove the modeling 

results it presented are insufficient by 

presenting a contrary modeling analysis, 

and argued that EPA has an obligation 

to do so. 

Response: EPA disagrees with WG’s 

contention that EPA is obligated to 

evaluate and disprove the modeling 

analyses it has submitted with a 

competing modeling analysis when 

other available information is available 

to dispute the modeling analysis. EPA’s 

interpretation of section 110(a)(2)(D) is 

that the statute does not explicitly 

require modeling, and while modeling 

can be useful in certain circumstances, 

there is no obligation to use it to 

evaluate whether or not there is 

significant contribution to 

nonattainment. Section 110(a)(2)(D)(i) 

does not specify the forms of evidence 

to be used for meeting the requirements, 

and the 2006 Guidance specifically 

recommends other forms of information 

that states might wish to evaluate as part 

of their section 110(a)(2)(D) 

submissions. We evaluated whether 

Idaho’s SIP met the requirement of 

section 110(a)(2)(D)(i) based on EPA’s 

2006 Guidance and have a reasonable 

basis, as discussed in the proposed 

approval, for concluding that Idaho has 

met the requirement of 110(a)(2)(D)(i) 

for the 1997 8-hour ozone and 1997 

PM2.5 NAAQS in the absence of a 

modeling analysis. 

Comment No. 11—WG also objected 

to EPA’s proposed approval of the Idaho 

submission on the grounds that it was 

based upon a ‘‘weight-of-evidence 

analysis,’’ and that no such weight of 

evidence test appears in the CAA 

generally, or in section 110(a)(2)(D) in 

particular. According to the commenter, 

there is no regulatory support for using 

a ‘‘weight-of-evidence’’ approach to 

assessing air quality impacts. The 

commenter asserted that EPA neither 

cited nor quoted regulations or policy 

that provides for this, and failed to lend 

any specific meaning to the phrase 

through its proposed approval. Finally, 

the commenter asserted, without 

explaining, its belief that EPA failed to 

address ‘‘several relevant factors related 

to the determination of whether Idaho 

contributes significantly to 

nonattainment undermines the agency’s 

reliance on any ‘weight-of-evidence’ 

approach.’’ 

EPA Response—EPA agrees with WG 

that neither the CAA generally, nor 

section 110(a)(2)(D) specifically, include 

the explicit phrase ‘‘weight of evidence.’’ 

It simply does not follow, however, that 

it is inappropriate for EPA to use such 

an approach in this context. As 

explained above, section 110(a)(2)(D) 

does not explicitly stipulate how EPA 

may assess whether there is a significant 

contribution to nonattainment in other 

states. Through past actions such as 

CAIR, EPA has used a weight of 

evidence approach to exclude some 

states from further consideration.20 As 

described above, in EPA’s 2006 

Guidance the Agency specifically 

recommended types of information that 

states might wish to rely upon to 

evaluate the presence of, and extent of, 

interstate transport for this purpose. 

EPA believes that a weight of evidence 

approach that properly considers 

appropriate evidence is sufficient to 

make a valid determination, as in this 

case. 

Specifically, EPA’s technical analysis 

in the September 13, 2010 proposed 

action underscores its reliance on 

implementation policies set in the EPA 

2006 Guidance: ‘‘EPA’s August 15, 2006, 

guidance to states concerning section 

110(a)(2)(D)(i) recommended various 

methods by which states might evaluate 

whether or not its emissions 

significantly contribute to violations of 

the 1997 ozone standards in another 

state. Among other methods, EPA 

recommended consideration of available 

EPA modeling conducted in 

conjunction with CAIR, or in the 

absence of such EPA modeling, 

consideration of other information such 

as the amount of emissions, the 

geographic location of violating areas, 

meteorological data, or various other 

forms of information that would be 

relevant to assessing the likelihood of 

significant contribution to violations of 

the NAAQS in another state [our 

emphasis].’’ 21 On the basis of this 

Guidance, Idaho and EPA chose to 

assess the impacts of emissions from 

Idaho sources on nonattainment areas 

for the 1997 ozone NAAQS and 1997 

PM2.5 NAAQS in surrounding states 

through a weight of evidence approach 


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22 ‘‘As discussed above, EPA applied a multifactor approach to identify the amounts of NOX

emissions that contribute significantly to 

nonattainment.* * *’’ 1998 SIP Call, 63 FR 57381, 

October 27, 1998. 

23EPA notes that WG appears to have incorrectly 

stated and conflated the two different standards 

presented in CAA section 110(a)(2)(D)(i)(I) in this 

comment. EPA assumes that, due to the placement 

of this comment in a section that WG entitled 

‘‘Measures in the SIP do not Appear to Ensure that 

Idaho will not Significantly Contribute to 

Nonattainment’’ and statements made later in the 

comment, that the comment applies only to EPA’s 

proposed approval of the nonattainment prong of 

110(a)(2)(D)(i)(I) and was not provided in reference 

to the maintenance prong. 

using quantitative and qualitative 

information such as monitoring data for 

those other states, Idaho’s distance from 

areas with monitors showing violation 

of the NAAQS, meteorological 

conditions, and other characteristics for 

those areas. EPA’s use of a weight of 

evidence analysis is by no means 

unusual for the assessment of ozone 

impacts through long range transport. 

The same analytical framework was 

used in the 1998 NOX SIP Call, as 

indicated under Section II.C., entitled 

‘‘Weight-of-Evidence Determination of 

Covered States.’’ 22 The differences 

between the specific types of evidence 

used in the NOX SIP Call and in our 

analysis do not invalidate the use of the 

weight of evidence approach. 

As for the commenter’s argument that 

EPA ‘‘fails to lend any specific meaning 

to the phrase through its proposed 

approval,’’ the Agency’s technical 

analysis described in the proposal did 

specify the characteristics, including 

limitations, of a weight of evidence 

analysis: ‘‘[f]urthermore * * * EPA 

notes that no single piece of 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 

violations of the 1997 8-hour ozone or 

1997 PM2.5 NAAQS in another state.’’ 

(75 FR 55496). 

Finally, as to the commenter’s 

assertion that EPA failed to consider 

‘‘several relevant factors’’ and thus failed 

to conduct an appropriate weight of 

evidence evaluation, EPA cannot weigh 

the validity of this comment in the 

absence of an explanation of what these 

factors might be. 

Comment No. 12—WG questioned 

whether a regulatory provision from 

Idaho’s SIP, IDAPA 58.01.013.203.02, 

that was identified in the proposed 

action constitutes a ‘‘prohibition on 

emissions that significantly interfere 

with nonattainment.’’ 23 WG argued that 

this provision does not appear to ensure 

compliance with section 

110(a)(2)(D)(i)(I) because, the 

commenter explains, the provision 

applies only to stationary sources 

(actually point sources) and not to 

mobile or field burning emissions, and 

that all sources must be considered in 

order to meet the requirements of the 

statute. The commenter alleged that 

110(a)(2)(D)(i)(II) applies to any source 

or other type of emission activity and, 

therefore, Idaho’s SIP provision is 

inadequate if it is limited in its 

application to stationary sources. WG 

went on to identify emission inventory 

information to support its argument that 

mobile source emissions and 

agricultural burning emissions are 

significant sources of emissions in 

Idaho. The commenter questioned the 

assertion that the abovementioned 

regulatory provision provides authority 

to limit a source’s emissions to ensure 

attainment in other states. WG also 

questioned how the provision would 

apply in attainment areas. Finally, the 

commenter concluded that the Idaho 

SIP does not appear to contain 

provisions that effectively prohibit 

emissions from any source from 

significantly contributing to 

nonattainment in any other state. 

EPA Response—EPA agrees with the 

commenter’s assertion that the 

requirements of section 110(a)(2)(D)(i)(I) 

are applicable to all source categories 

and not only to stationary sources. The 

commenter seems to have read EPA’s 

proposed action to imply that the 

provisions cited by Idaho are the only 

consideration in evaluating whether 

Idaho has met the requirement regarding 

whether or not a state’s emissions 

significantly contribute to violations of 

1997 ozone and 1997 PM2.5 standards in 

another state. In fact, these provisions, 

which provide IDEQ with the authority 

to require a permit if emission rate 

reductions are necessary to attain any 

ambient air quality standard, were 

identified by EPA in the proposed 

action as ‘‘additional support for [EPA’s] 

conclusion that emissions from Idaho 

sources do not significantly contribute 

to nonattainment in any other state 

* * *.’’ As noted in EPA’s proposed 

action, no single piece of information 

was by itself dispositive in evaluating 

Idaho’s potential contribution to 

nonattainment in another state. EPA has 

taken into account the Idaho SIP as a 

whole, which includes but is not 

limited to the cited permitting 

provisions, and the actual contribution 

of emissions from Idaho to 

nonattainment receptors in other states 

to evaluate whether the significant 

contribution element has been met. 

EPA disagrees with the commenter’s 

apparent view that under section 

110(a)(2)(D) SIPs must contain literal 

provisions prohibiting significant 

contribution to nonattainment in any 

other state, or, for that matter, to contain 

any particular words or generic 

prohibitions. Instead, EPA believes that 

the statute requires a state’s SIP to 

contain substantive emission limits or 

other provisions that in fact ensure that 

sources located within the state will not 

produce emissions that have such an 

effect in other states. In conducting its 

analysis of whether or not the state’s SIP 

is adequate, EPA evaluates the actual 

contribution of a state’s emissions to 

nonattainment in another state and does 

not base its analysis on the written 

provisions of the SIP alone. Therefore, 

EPA believes that satisfaction of the 

‘‘significant contribution’’ requirement is 

not to be demonstrated through a literal 

requirement for a prohibition of the type 

advocated by the commenter. 

EPA’s past application of section 

110(a)(2)(D) did not require the literal 

prohibition advocated by the 

commenter. For example, in 1998 NOX

SIP call (63 FR 57356, October 27, 1998) 

EPA indicated that ‘‘the term ‘prohibit’ 

means that SIPs must eliminate those 

amounts of emissions determined to 

contribute significantly to 

nonattainment * * *.’’ As a result, the 

first step of the process to determine 

whether this statutory requirement is 

satisfied is the factual determination of 

whether a state’s emissions contribute 

significantly to nonattainment in 

downwind areas. See 2005 CAIR Rule 

(70 FR 25162) and 1998 NOX SIP Call 

(63 FR 57356). If this factual finding is 

in the negative, as is the case for EPA’s 

assessment of the contribution from 

emissions from Idaho, then section 

110(a)(2)(D)(i)(I) does not require any 

changes to a state’s provisions. If, 

however, the evaluation reveals that 

there is such a significant contribution 

to nonattainment in other states, then 

EPA requires the state to adopt 

substantive provisions to eliminate 

those emissions. The state could achieve 

these reductions through traditional 

command and control programs, or at its 

own election, through participation in a 

cap and trade program. Thus, EPA’s 

approach in this action is consistent 

with the Agency’s interpretation of 

110(a)(2)(D)(i) in the 2006 guidance, the 

CAIR Rule, and the NOX SIP call, none 

of which required the pro forma literal 

‘‘prohibition’’ of the type advocated by 

the commenter. 

B. Comments Relating to the ‘‘Interfere 

With Maintenance’’ Element 

Comment No. 1—The commenter 

stated that EPA inappropriately defined 

the term ‘‘interfere with maintenance.’’ It 

argued that EPA’s definition appeared to 

be ‘‘inappropriately conflated with the 


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24As EPA noted in the proposal, the term 

‘‘interfere with maintenance’’ is not defined in the 

CAA. As such, the term is ambiguous and EPA’s 

interpretation of that term in this action is both 

reasonable and consistent with the overall goals of 

the CAA. By this approach, EPA is giving 

independent meaning to the term and supporting 

that interpretation with technical analysis to apply 

it to the facts of this action. 

definition of nonattainment.’’ It argued 

that the definition of maintenance 

appeared to be tied to nonattainment, 

asserting that ‘‘unless an area has 

violated or is in violation of the 

NAAQS, the agency will not consider 

whether Idaho is interfering with that 

area’s ability to maintain compliance 

with the NAAQS.’’ For this reason, it 

argued EPA did not give independent 

meaning to the ‘‘interfere with 

maintenance’’ prong of section 

110(a)(2)(D)(i)(I). 

The commenter also maintains that 

EPA’s analysis did not consider Idaho’s 

impacts on neighboring states that have 

not previously violated, but that ‘‘may 

be barely attaining the NAAQS.’’ To 

illustrate its contention that EPA has 

inappropriately defined ‘‘interference 

with maintenance,’’ the commenter 

pointed to information regarding Cache 

Valley, Utah, which it describes as an 

example of an area that has not violated 

the 1997 24-hour PM2.5 NAAQS, but 

that may be barely attaining the NAAQS 

and should, therefore, be classified as a 

maintenance receptor. The commenter 

did not provide any other concrete 

examples of areas that EPA should have 

identified as maintenance receptors. 

Response—The definition of 

maintenance used by EPA is consistent 

with the direction given to EPA by the 

Court of Appeals for the DC Circuit in 

North Carolina v. EPA, 531 F.3d 896 

(DC Cir. 2008).24 In that case, the court 

analyzed the definition of ‘‘interfere 

with maintenance’’ used in the CAIR 

rule. The court found that the definition 

EPA used ‘‘gave no independent 

significance to the ‘interfere with 

maintenance’ prong of section 

110(a)(2)(D)(i)(I) to separately identify 

upwind sources interfering with 

downwind maintenance.’’ North 

Carolina at 910. It further reasoned that 

‘‘[u]nder EPA’s reading of the statute, a 

state can never ‘‘interfere with 

maintenance’’ unless EPA determines 

that at one point it ‘‘contribute[d] 

significantly to nonattainment.’’ Id. 

Based on this analysis, the court found 

the definition unlawful holding that 

‘‘[b]ecause EPA describes CAIR as a 

complete remedy to a section 

110(a)(2)(D)(i)(I) violation and does not 

give independent significance to the 

’interfere with maintenance’ language to 

identify upwind states that interfere 

with downwind maintenance, EPA 

unlawfully nullifies that aspect of the 

statute and provides no protection for 

downwind areas that, despite EPA’s 

predictions, still find themselves 

struggling to meet NAAQS due to 

upwind interference in 2010.’’ Id. at 

910–911. 

The approach used by EPA to 

evaluate Idaho’s SIP submission and to 

determine whether emissions from 

sources in Idaho interfere with 

maintenance in any other state directly 

addresses these flaws. It gives 

significant independent meaning to the 

term ‘‘interfere with maintenance.’’ It 

establishes a process to identify any 

specific receptors in downwind states 

that, even though they are projected to 

be in attainment and thus would not be 

nonattainment receptors, may have 

difficulty maintaining the NAAQS in 

question. These receptors are referred to 

as maintenance receptors. 

The methodology EPA used to 

identify maintenance receptors gives 

independent meaning to the term 

‘‘interfere with maintenance’’ and 

establishes a process to identify 

projected attainment receptors that, 

based on the historic variability of air 

quality at that site (which may be due 

to variability in emissions and/or 

meteorology), may have difficulty 

maintaining the standard. As explained 

in greater detail below, the commenter’s 

objection to EPA’s approach appears to 

be based on the misconception that the 

methodology EPA used to identify 

maintenance sites was dependent on 

base year NAAQS violations. 

The commenter’s statement that 

EPA’s designation of maintenance 

receptors is ‘‘firmly hitched to a finding 

that the maximum design value based 

on a single three-year period between 

2003 and 2007 is in excess of the 

NAAQS’’ appears to be based on a 

misunderstanding of the methodology 

used by EPA to identify maintenance 

receptors. EPA’s methodology did not, 

as the commenter appears to assume, 

require a site to have a design value 

above the NAAQS for one of the three 

base periods (2003–2005, 2004–2006, 

2005–2007) to be considered a 

maintenance site. The methodology is 

based on an analysis of the future year 

average and future year maximum 

design values. It does not depend on 

whether the base year design values 

exceed the NAAQS. In the proposal, 

EPA explained that ‘‘EPA identified 

those sites that are projected to be 

attainment based on the 5-year weighted 

average design value, but that have a 

maximum design value (based on a 

single three-year period) that exceeds 

the NAAQS, as maintenance sites.’’ (75 

FR 52697). The maximum design value 

referenced in this sentence is the 

maximum future design value 

calculated using each of the three base 

design value periods separately. 

Whether or not one of the three base 

period design values exceeded the 

NAAQS was not a factor considered in 

determining whether a site was a 

maintenance receptor. 

To better understand this concept, it 

is useful to compare the methodologies 

used in the Transport Rule (TR) 

proposal (75 FR 45210, Aug. 2, 2010) to 

identify nonattainment and 

maintenance receptors. In the TR 

proposal, base period (2003–2007) 

ambient data were projected to the 

future (using model outputs), to identify 

both nonattainment and maintenance 

receptors. In both cases, receptors were 

identified by projected future design 

values; however, because more 

conservative data were used for the 

maintenance analysis, this analysis 

could identify receptors that were 

projected by the nonattainment analysis 

to be in attainment, yet might have 

difficulty attaining the standard due to 

historic variability of air quality at that 

site. To identify future nonattainment 

sites EPA calculated the future year 

design values by projecting the 5-year 

weighted average design value for each 

site. Only if this future year design 

value exceeded the NAAQS was the site 

considered to be a nonattainment 

receptor. However, to identify projected 

maintenance sites we used a different 

methodology that took into account 

historic variability in air quality at each 

receptor. For this approach EPA 

calculated the maximum future year 

design value by processing each of the 

three base design value periods (2003– 

2005, 2004–2006, and 2005–2007) 

separately. The highest of the three 

future values is the maximum design 

value, which is used to determine 

maintenance receptors. 

In this way, EPA’s analysis identifies 

those areas that are projected to be 

attainment, but may have difficulty 

maintaining attainment of the standard, 

for example in a year with particularly 

severe meteorology (weather that is 

conducive to ozone and/or particulate 

formation). In other words, this analysis 

does exactly what the DC Circuit 

directed EPA to do in North Carolina, 

531 F.3d 896. It gave independent 

meaning to the ‘‘interfere with 

maintenance’’ prong of 110(a)(2)(D)(i) 

and is providing protection to any areas 

that, although they are predicted to 

attain the standard (and thus upwind 

sources could not be found to 

significantly contribute to 

nonattainment in that area) may have 


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25Commenter referenced the Colorado 

Department of Public Health and Environment’s 

‘‘2010 Ozone Attainment Demonstration Modeling 

for the Denver 8-hour Ozone State Implementation 

Plan Control Strategy’’ and the Environ modeling 

report ‘‘Final 2010 Ozone Attainment 

Demonstration Modeling for the Denver 8-hour 

Ozone State Implementation Plan’’ 

difficulty maintaining the standard. 

North Carolina. at 911. 

EPA used this same approach to 

identify any potential maintenance 

receptors for purposes of evaluating 

Idaho’s SIP submission. For the reasons 

explained above, this approach is both 

reasonable and consistent with the 

direction given to EPA by the DC Circuit 

in North Carolina. 

As explained above, EPA established 

a methodology to identify sites that may 

have difficulty maintaining the 1997 8- 

hour ozone or 1997 PM2.5 NAAQS. This 

process identifies any specific receptors 

in downwind states that, even though 

they are projected to be in attainment 

and thus would not be nonattainment 

receptors, may have difficulty 

maintaining the NAAQS in question. 

Based on this methodology, EPA 

projected that the Cache Valley in Utah 

will not have difficulty meeting the 

1997 8-hour ozone NAAQS or the 1997 

PM2.5 NAAQS because none of the 

future year design values exceeded the 

NAAQS and Cache Valley is not a 

maintenance receptor. 

EPA notes that, except for Cache 

Valley, Utah, the commenter provides 

no specific examples or facts to support 

its arguments that there are areas in 

neighboring states which are ‘‘barely 

attaining the NAAQS.’’ In the absence of 

any specific comments regarding the 

location of monitoring receptors, 

monitoring concentrations, or time 

periods during which these areas were 

purportedly ‘‘barely attaining’’ the 

NAAQS, EPA cannot respond to the 

commenter’s generic concerns about 

interference with maintenance in the 

neighboring states of Montana, Nevada, 

Oregon, Montana, Wyoming, and other 

areas of Utah. EPA’s analysis shows that 

there are no sites in any states adjacent 

to Idaho with design values exceeding 

the 65 ug/m3 which should accordingly 

be identified as maintenance receptors. 

WG provided only the example of 

Cache Valley, Utah, as an area that EPA 

should have identified as a maintenance 

receptor. The commenter appears to 

implicitly argue that EPA has 

inappropriately established an 

interference with maintenance 

threshold, although it did not identify 

specific criteria that should warrant 

designating an area as a maintenance 

receptor. Even if EPA did not rely on the 

methodology discussed above to give 

meaning to the ‘‘interfere with 

maintenance’’ prong of section 

110(a)(2)(D), the commenter’s argument 

that Cache County is ‘‘barely attaining’’ 

the NAAQS is not persuasive. The data 

pointed to by the commenter is not 

sufficient to support a reasonable 

conclusion that the area warrants 

evaluation as a maintenance receptor. 

The commenter identified the four 

highest monitored values for PM2.5 at 

the Cache County monitor for each year 

from 2005 through 2010. However, 

EPA’s regulations establish that 

attainment of the PM2.5 NAAQS is 

determined when the three-year average 

of the 98th percentile value at each 

monitoring site is less than or equal to 

65 μg/m3. The 98th percentile value for 

Cache County cannot be evaluated by 

considering only the four highest 

monitored readings during each of the 

years cited by the commenter. In fact, all 

of the values cited by the commenter 

would be eliminated from consideration 

in an attainment analysis. EPA 

concludes that this data is not 

sufficiently persuasive to warrant 

identifying Cache County as a 

maintenance receptor. 

Although the commenter did not 

provide a full data set in its comments, 

EPA has analyzed a complete data set 

for the Cache County monitor and 

determined that the highest three yearaverage of the 98th percentile for the 

monitor is only 66% of the standard. 

EPA computed the highest 3-year 

average of the 98th percentile values for 

each of the three-year periods covered 

by the 2005–2010 period that the 

commenter references. The highest 

value for any complete three-year 

periods was 42 μg/m3, well below 65 μg/ 

m3. EPA disagrees with the commenter’s 

conclusion that there is a reasonable 

basis for characterizing this area as 

‘‘barely attaining’’ the NAAQS or one 

that warrants additional evaluation as a 

maintenance receptor. 

Comment No. 2—The commenter 

cited a variety of information suggesting 

that receptors in the Denver/North Front 

Range (Denver/NFR) area should also be 

considered for maintenance purposes 

under 110(a)(2)(D)(i) in this action. The 

commenter points out that as EPA itself 

has stated that ‘‘Data for 2005–2007 and 

2006–2008 reflect violations of the 8- 

hour ozone NAAQS at the Rocky Flats 

North monitor (values of {0.085} and 

0.086 ppm, respectively).’’ The 

commenter also argued that modeling 

prepared in conjunction with Colorado’s 

Denver/NFR attainment demonstration 

shows that by 2010, the three-year 

design value is only projected to be 

lowered to 0.084 parts per million, 

barely in compliance with the NAAQS, 

and that certain portions of the Denver/ 

NFR area of Colorado would violate the 

1997 ozone NAAQS in 2010 at grid cells 

west of Fort Collins. The commenter 

referenced several documents that are 

part of the Colorado’s Denver/NFR 8- 

hour Ozone Attainment Demonstration 

in support of its arguments. The 

commenter cited the report’s language 

that indicated that the modeling 

projection of a value above the 1997 8- 

hour standard to the west of Fort Collins 

is not ‘‘implausible’’ explaining, ‘‘[i]n the 

case of the Denver ozone modeling, 

higher ozone concentrations are 

estimated west of Fort Collins than at 

the locations of the two monitors in Fort 

Collins on some days and this does not 

appear to be an error in the modeling 

system’’.25

The commenter argued that EPA’s 

failure to consider the Denver/NFR area 

as a receptor for evaluating interference 

with maintenance in this action reflects 

the very problem that the DC Circuit 

warned could result without giving 

independent meaning to the term 

‘‘interfere with maintenance.’’ 

Response—EPA disagrees with the 

commenter’s argument that EPA has 

inappropriately identified the correct 

monitors for maintenance receptors. As 

discussed in greater detail in the 

previous response to comment, EPA has 

selected a method that identifies 

maintenance receptors separately from 

nonattainment receptors and gives an 

independent meaning to the interfere 

with maintenance prong of section 

110(a)(2)(D)(i). EPA has consistently 

applied this method to all potential 

receptors in states potentially impacted 

by Idaho’s emissions including those in 

the Denver/NFR area. 

The commenter’s argument that EPA 

did not consistently identify 

maintenance receptors is premised on 

the same fundamental 

misunderstanding (discussed in the 

previous response to comment 

addressing the ‘‘interfere with 

maintenance’’ prong) that EPA’s 

identification of nonattainment 

receptors was based on current or past 

NAAQS violations. As explained above, 

this is not correct. EPA did not base its 

identification of maintenance receptors 

on an analysis of whether air quality at 

those receptors exceeded the NAAQS in 

the base years. The methodology EPA 

used to identify maintenance areas takes 

into account historic variability of 

emissions at specific monitoring sites to 

analyze whether or not monitoring sites 

projected to be in attainment in 2012 

will nonetheless remain at risk of 

slipping into nonattainment in that year. 

The commenter provided a number of 

modeling or monitoring analyses for 


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26EPA’s ‘‘Guidance on the Use 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. 

27 75 Federal Register 40 CFR part 52 [EPA–R08– 

OAR–2010–0285; FRL–9177–2], Proposed Rule, 

‘‘Approval and Promulgation of Air Quality 

Implementation Plans; Colorado; Attainment 

Demonstration for the 1997 8-Hour Ozone Standard, 

and Approval of Related Revisions’’; pages 42346– 

42361. 

28 Id. 

29 Id., page 32. 

2010 or earlier. As we have addressed 

in responses elsewhere in this notice, 

EPA continues to believe 2012 is the 

appropriate year for this analysis. Thus, 

modeling or monitoring data for other 

years is not directly relevant to this 

rulemaking. Nonetheless, below we 

address the commenter’s specific 

assertions about the modeling. 

The commenter asserts that 

monitoring data for 2005–07 and 2006– 

08 for the Rocky Flats North monitor 

reflect violations of the 8-hour NAAQS 

and therefore EPA should consider this 

Rocky Flats North monitor as a 

‘‘maintenance receptor.’’ The commenter 

further cites to modeling prepared in 

conjunction with Colorado’s Denver/ 

NFR attainment demonstration to 

support its assertion that EPA has 

applied inconsistently its definition of 

interference with maintenance. The 

modeling data referenced by the 

commenter, however, only identifies 

monitors that, in the commenter’s view, 

are at risk of being in nonattainment or 

having maintenance problems in 2010. 

The monitoring data cited indicates 

high ozone levels in the past. The 

underlying issue raised is thus 

substantively the same as that raised in 

Comment No. 3 below which argues that 

EPA’s analysis is faulty because it 

identifies receptors likely to have 

difficulty maintaining the standard in 

2012 and not at the present or in the 

past. EPA’s response to Comment No. 3 

below, illustrates how its approach, 

based on modeling analyses that 

identify receptors at risk for 

maintenance in the year 2012, is 

appropriate and consistent with the D.C. 

Circuit decision in North Carolina v. 

EPA. 

EPA’s method is based on model 

projection values that take into account 

multi-year variability in ozone data at 

specific monitors. For identification of 

maintenance receptors, EPA utilized the 

monitoring data from the 2003–2007 

period to calculate 2012 future year 

modeling design value projections. The 

2003–07 period includes three Design 

Value (DV) periods (2003–2005, 2004– 

2006, and 2005–2007). The 2012 future 

year DVs were calculated by 

multiplying a 3-year DV (base year) by 

the ratio of the Future Year average of 

the daily 8-hour ozone maximums 

around a monitor over the Base Year 

average of the daily 8-hour ozone 

maximums around a monitor. This 

calculation was performed for each of 

the three 3-year DVs (2003–2005, 2004– 

2006, and 2005–2007). This approach 

yielded three different projected 2012 

design values and thus, tests for 

variability in meteorology. If any of the 

three 2012 projections was above the 

1997 ozone standard, then the receptor 

would be considered a maintenance 

receptor. None of the 2012 projections 

for the Denver/NFR area was above the 

standard so the area was not considered 

a maintenance area. This approach was 

the same as the approach used for every 

potential receptor evaluated. It is worth 

noting that EPA’s analysis included the 

2005–2007 data for the Rocky Flats 

monitor (which is one of the highest 

monitored DVs in recent years for this 

monitor) that the commenter raised as a 

concern and pursuant to its 

methodology as previously described 

EPA’s analysis determined that the 

Rocky Flats monitor would not be a 

maintenance receptor in 2012. 

Further, EPA disagrees with 

commenter’s conclusion that the 

modeling performed for the Denver/NFR 

attainment demonstration with the 2010 

model projections establishes that any 

of the areas identified will have 

maintenance problems for the 1997 8- 

hour ozone NAAQS. We disagree with 

the commenter’s conclusion that the 

Denver/NFR area monitors should be 

identified as ‘‘maintenance receptors’’ in 

large part because he bases his 

conclusion on projections for 2010 

instead of 2012. This modeling used 

projections for 2010 not 2012, which as 

explained above and in response to 

Comment No. 3 below is not the correct 

year for comparison, given the approach 

EPA has developed for determining 

maintenance receptors. EPA’s analysis 

of maintenance receptors, which is 

based on the approach developed in the 

Transport Rule Proposal to be consistent 

with the DC Circuit’s opinion in North 

Carolina v. EPA and uses projections for 

2012, did not identify any maintenance 

receptors in the Denver/NFR area. This 

conclusion is consistent with evidence 

suggesting emissions are likely to trend 

downward (for example, with two more 

years of fleet turnover, this modeling 

would likely have projected lower levels 

of ozone in 2012) and preliminary 

monitoring data for 2010, which 

indicates that the Denver/NFR area is 

meeting the 1997 ozone standard. 

Further, EPA has reviewed Colorado’s 

attainment demonstration for the 

Denver/NFR area and proposed that the 

combination of the modeling and weight 

of evidence analyses demonstrates that 

Denver will be in attainment in 

2010.26 27

In addition, the commenter’s concern 

that an area west of Fort Collins, might 

exceed 84 ppb in 2010 is based on 

exceedance values in the Colorado 

modeling analysis from a special 

analysis, called the Unmonitored Area 

Analysis (UAA), that is recommended 

for model grid cells that are not 

analyzed in the monitor based 

attainment demonstration because they 

are not located near a monitor. EPA 

does not believe that the UAA 

establishes that this area should be 

considered a maintenance receptor area 

for the purposes of 110(a)(2)(D)(i). 

First, the UAA analysis is for 2010, 

which as noted above is not the correct 

analysis year. Second, EPA guidance 

indicates that NAAQS violations in the 

UAA should be handled on a case by 

case basis.28 The guidance stresses that 

due to the lack of measured data, the 

examination of ozone concentrations as 

part of the unmonitored area analysis is 

more uncertain than the monitor based 

attainment test. This is true even in 

situations such as this where, as the 

commenter points out, no known errors 

were identified by the contractor in the 

modeling analysis. As a result, the UAA 

results are recommended to be treated 

as a separate test from the monitor based 

attainment test with less weight put on 

the conclusions of the UAA analysis. 

EPA’s attainment demonstration 

guidance indicates ‘‘[w]hile it is 

expected that States will implement 

additional emission controls to 

eliminate predicted violations of the 

monitor based test, the same 

requirements may not be appropriate in 

unmonitored areas.’’ 29 The guidance 

recommends that it may be appropriate 

to deploy additional monitors in an area 

where the unmonitored analysis 

indicates a potential future year 

violation. 

To address the concerns raised by the 

UAA, Colorado installed an additional 

ozone monitor in the area West of Fort 

Collins to determine whether the model 

predicted ozone concentrations are, in 

fact, valid. The special purpose monitor, 

located in Rist Canyon, began operation 

on May 14, 2009. The Rist Canyon 

monitoring station has collected data for 

two ozone seasons (approximately 16 

months) since it began operating and the 

fourth highest daily maximum 8-hour 

average ozone concentration reading is 

69 ppb for May through December of 


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30The Rist Canyon monitoring station uses a 

Federal Equivalent Method (FEM) and follows the 

quality assurance requirements of 40 CFR part 58 

appendix A. Ozone data collected at this 

monitoring station is eligible for comparison to the 

ozone NAAQS after the monitor has operated for 

more than 24 months per 40 CFR 58.30(c). Design 

values, however, are based on the 3-year average of 

the annual fourth highest daily maximum 8-hour 

average ozone concentration (see 40 CFR part 50, 

appendix D). 

2009 and 72 ppb for January through 

August 2010.30

Therefore, EPA does not believe the 

modeling performed for the State of 

Colorado’s Denver/NFR area SIP can 

support the conclusion that this area 

should be considered a maintenance 

receptor area for the purposes of 

110(a)(2)(D)(i). The methodology 

developed to identify maintenance 

receptors for the purpose of analyzing 

interference with maintenance with 

respect to the 1997 ozone and PM 2.5

NAAQS relies on base period 

monitoring data to identify monitor 

locations that are projected to have 

maintenance problems in 2012. The 

methodology does not identify receptors 

based on modeling data alone. While 

the monitor has not operated long 

enough to account for variability in 

ozone levels, the newly installed 

monitor in the relevant area is reading 

well below the standard and this fact 

further confirms that the modeling 

results and the UAA results do not 

support the conclusion that receptors in 

the Denver/NFR area should be 

considered maintenance receptors for 

the purpose of CAA section 110(2)(D)(i). 

In conclusion, EPA disagrees with the 

commenter. We have used a fully 

consistent approach in identifying areas 

that may have difficulty in maintaining 

attainment of the NAAQS. It is these 

areas that we have further evaluated to 

see if Idaho’s emissions would interfere 

with maintenance of the NAAQS. 

Comment No. 3—The commenter also 

argued that EPA’s analysis ignores 

whether emissions from Idaho sources 

are at present interfering with 

maintenance in other states. The 

commenter argued that EPA erred by 

considering only whether Idaho 

emissions will interfere with 

maintenance of the NAAQS in 2012 at 

monitors that would then be considered 

‘‘maintenance receptors.’’ It argues that 

this approach is inconsistent with the 

approach taken to determine whether 

Idaho significantly contributes to 

nonattainment in other states. The 

commenter agreed that ‘‘EPA should 

ensure that Idaho does not interfere 

with maintenance or contribute 

significantly to nonattainment in other 

states in the future,’’ but argued that ‘‘the 

agency’s duties under Section 

110(a)(2)(D)(i) apply both in the present 

and the future.’’ In short, the commenter 

argued that EPA’s approach is flawed 

simply because EPA evaluated whether 

or not there is significant contribution to 

nonattainment in other states looking at 

current data, whereas EPA evaluated 

whether there is interference with 

maintenance looking at future projected 

data. 

Response: EPA disagrees with the 

commenter concerning the evaluation of 

significant contribution versus 

interference with maintenance. Section 

110(a)(2)(D)(I)(i) of the Clean Air Act 

requires states to submit SIPs within 3 

years of promulgation or revision of a 

NAAQS that: 

(D) contain adequate provisions— 

(i) prohibiting * * * 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 or, interfere with maintenance 

by, any other State with respect to any such 

national primary or secondary ambient air 

quality standard, or 

(II) interfere with measures required to be 

included in the applicable implementation 

plan for any other State under part C of this 

subchapter to prevent significant 

deterioration of air quality or to protect 

visibility. 

In determining the appropriate year to 

analyze in determining whether 

emissions from Idaho will interfere with 

maintenance by any other State, EPA 

used an approach upheld by the DC 

Circuit in North Carolina v. EPA. In that 

case, the court examined EPA’s 

definition of ‘‘will’’ in ‘‘will contribute 

significantly.’’ The placement of the 

word ‘‘will’’ at the end of section 

110(a)(2)(D)(i) clarifies that it applies to 

all of the provisions that follow—both 

those in 110(a)(2)(D)(i)(I) and those in 

110(a)(2)(D)(i)(II). Thus the DC Circuit’s 

discussion of the meaning of the word 

‘‘will’’ in ‘‘will significantly contribute’’ 

also applies to the meaning of the word 

‘‘will’’ in ‘‘will * * * interfere with 

maintenance.’’ 

In North Carolina v. EPA, the DC 

Circuit rejected North Carolina’s 

argument that EPA erred in limiting its 

analysis of downwind areas by 

excluding areas that were currently 

monitored nonattainment but projected 

to be in attainment at a future date. Like 

the commenter argues here, North 

Carolina had argued that EPA was 

obligated to analyze the significant 

contribution of states that were 

contributing to areas of North Carolina 

that were in nonattainment at the time 

the rule was promulgated, even though 

those areas were projected to come into 

attainment by the year selected for the 

future base case analysis. In rejecting 

this argument, the DC Circuit explained 

that the approach used by EPA was 

identical to the one used previously in 

the NOX SIP Call and that ‘‘because 

‘will’ can mean either certainty or 

indicate the future tense,’’ EPA’s 

approach was reasonable. In other 

words, the court approved EPA’s 

approach that entailed the evaluation of 

interstate transport impacts at a future 

date in time. 

Contrary to the assertions of the 

commenter, EPA believes that 

evaluation of interference with 

maintenance using a future date is the 

most appropriate approach for that 

requirement. As explained in the 

proposed action, the court decision 

affecting the CAIR rule required EPA to 

reevaluate its approach to the interfere 

with maintenance requirement of 

section 110(a)(2)(D) and to develop a 

new approach to give that requirement 

separate meaning. In doing so, EPA has 

developed an approach that necessarily 

requires a number of years of data, and 

an analysis that evaluates where there 

may be difficulties with maintaining 

attainment at a specific point in time, in 

this instance 2012. It is reasonable and 

appropriate for EPA to use, in this 

rulemaking, the current approach to 

identifying maintenance receptors for 

purposes of section 110(a)(2)(D) that 

EPA developed to be consistent with the 

direction given to EPA in North 

Carolina v. EPA. 

Finally, EPA notes that the text of 

section 110(a)(2)(D)(i) does not 

explicitly specify how to evaluate the 

existence of, or extent of, interstate 

transport and whether that interstate 

transport is of sufficient magnitude to 

significantly contribute to 

nonattainment or interfere with 

maintenance as a regulatory matter. The 

statutory language is ambiguous on its 

face and EPA must reasonably interpret 

that language when it applies it to 

factual situations before the Agency. 

EPA’s 2006 Guidance explicitly stated 

our view that the ‘‘precise nature and 

contents of such a submission [are] not 

stipulated in the statute’’ and that the 

contents of the SIP submission ‘‘may 

vary depending upon the facts and 

circumstances related to the specific 

NAAQS.’’ Moreover, within that 

Guidance, EPA expressed its view that 

‘‘the data and analytical tools available’’ 

at the time of the SIP submission 

‘‘necessarily affect * * * the content of 

the required submission.’’ As discussed 

above in response to comments 

regarding the ‘‘significant contribution 

to nonattainment’’ element, the state’s 

submittal and EPA’s evaluation of that 

submittal were consistent with the 2006 


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Federal Register / Vol. 75, No. 227 / Friday, November 26, 2010 / Rules and Regulations 72717 

Guidance and considered the type of 

information (such as monitoring data in 

Idaho and downwind states, 

geographical and meteorological 

information, and technical studies of the 

nature and sources of nonattainment 

problems in various downwind states) 

that EPA recommended as relevant for 

evaluating that element. EPA’s approach 

to evaluating whether Idaho’s emissions 

significantly contribute to 

nonattainment in another state is 

consistent with the 2006 Guidance and 

is a reasonable interpretation of section 

110(a)(2)(D)(i). 

Just as EPA has used the best 

available information to make its 

determination regarding Idaho’s 

potential interference with maintenance 

in another state, it has developed and 

applied a methodology to evaluate 

whether Idaho’s emissions potentially 

contribute significantly to 

nonattainment of the NAAQS in another 

state that is based upon consideration of 

information that is consistent with the 

2006 Guidance, past EPA analyses of 

significant contribution, and reasonably 

appropriate for that purpose. As was 

explained in the proposed action and in 

this final action’s response to comments 

pertaining to the ‘‘significant 

contribution to nonattainment’’ analysis 

above, section 110(a)(2)(D) is ambiguous 

with regard to the methods and 

standards applicable to a significant 

contribution to nonattainment 

determination. Therefore, EPA must 

interpret those provisions, and the 

Agency’s interpretation is subject to 

judicial deference so long as it is a 

reasonable construction of the statute. 

Chevron, U.S.A., Inc. v. NRDC, Inc., 467 

U.S. 837. EPA does not agree with the 

commenter’s contention that EPA’s 

approach to the ‘‘interference with 

maintenance’’ and ‘‘significant 

contribution to nonattainment’’ prongs 

of section 110(a)(2)(D) are flawed. 

Rather, each analysis is based upon the 

best available information and is a 

reasonable interpretation and 

application of the statute’s 

requirements. 

C. Comment Relating to Section 110(l) 

Comment No. 1—The commenter 

argued that EPA cannot approve the 

section 110(a)(2)(D) submission from 

Idaho because the state and EPA did not 

comply with section 110(l). The 

commenter argues that a section 110(l) 

analysis must consider all NAAQS once 

they are promulgated, and that EPA’s 

analysis under section 110(l) was 

inadequate. 

EPA Response—EPA agrees that a 

required section 110(l) analysis must 

consider the potential impact of a 

proposed SIP revision on attainment 

and maintenance of all NAAQS that are 

in effect and impacted by a given SIP 

revision. However, EPA disagrees that it 

failed to comply with the requirements 

of section 110(l) or that section 110(l) 

requires disapproval of the SIP 

submission at issue here. 

Section 110(l) provides in part that: 

‘‘[t]he Administrator shall not approve a 

revision of a plan if the revision would 

interfere with any applicable 

requirement concerning attainment and 

reasonable further progress * * *, or 

any other applicable requirement of this 

chapter.’’ EPA has consistently 

interpreted Section 110(l) as not 

requiring a new attainment 

demonstration for every SIP submission. 

EPA has further concluded that 

preservation of the status quo air quality 

during the time new attainment 

demonstrations are being prepared will 

prevent interference with the states’ 

obligations to develop timely attainment 

demonstrations. 70 FR 58134, 58199 

(October 5, 2005); 70 FR 17029, 17033 

(April 4, 2005); 70 FR 53, 57 (January 3, 

2005); 70 FR 28429, 28431 (May 18, 

2005). 

Idaho’s submission is the initial 

submission by the state to address for 

the 1997 8-hour ozone and PM2.5

NAAQS the first three elements of 

section 110(a)(2)(D)(i): (1) Significant 

contribution to nonattainment in any 

other state, (2) interference with 

maintenance by any other state, and (3) 

interference with any other state’s 

required measures to prevent significant 

deterioration (PSD) of its air quality. 

This submission does not revise or 

remove any existing emissions limit for 

any NAAQS, or any other existing 

substantive SIP provisions relevant to 

the 1997 8-hour ozone and 1997 PM2.5

NAAQS. Simply put, it does not make 

any substantive revision that could 

result in any change in emissions. As a 

result, the submission does not relax 

any existing requirements or alter the 

status quo air quality. Therefore, 

approval of the Idaho interstate 

transport SIP will not interfere with 

attainment or maintenance of any 

NAAQS. 

The commenter did not provide any 

specific basis for concluding that 

approval of this SIP submission would 

interfere with attainment or 

maintenance of a NAAQS, or with any 

other applicable requirement of the 

Clean Air Act. EPA concludes that 

approval of the submission will not 

make the status quo air quality worse, 

and is in fact consistent with the 

development of an overall plan capable 

of meeting the Act’s attainment 

requirements. Accordingly, EPA finds 

that approval of the submission is 

consistent with the requirements of 

section 110(l). 

IV. Final Action 

EPA is approving revisions to the 

Idaho SIP, submitted on June 28, 2010, 

which adequately demonstrate that for 

the 1997 8-hour ozone and 1997 PM2.5

NAAQS, air pollutant emissions from 

sources within Idaho do not (1) 

significantly contribute to 

nonattainment of the NAAQS in any 

other state or (2) interfere with 

maintenance of the NAAQS by any 

other state. EPA is also approving the 

provisions in the Idaho SIP relating to 

interference with any other state’s 

required measures to prevent significant 

deterioration. In its September 13, 2010, 

proposal (75 FR 55494), EPA proposed 

to approve Idaho’s SIP as adequate for 

purposes of meeting the requirements of 

section 110(a)(2)(D)(i)(II) contingent 

upon EPA taking final action to approve 

revisions to Idaho’s PSD requirements 

that were consistent with our proposed 

action on these PSD requirements on 

March 18, 2010. 75 FR 13058. We 

received no comments on this proposed 

contingent approval. EPA’s Region 10 

Regional Administrator signed the final 

approval of the PSD program revisions 

on November 10, 2010. These approved 

provisions ensure that there will be no 

interference with any other state’s 

required PSD measures because Idaho’s 

SIP meets current CAA requirements for 

PSD. 

In conclusion, EPA is approving 

revisions to the Idaho SIP, submitted on 

June 28, 2010, because they adequately 

demonstrate that for the 1997 8-hour 

ozone and 1997 PM2.5 NAAQS, air 

pollutant emissions from sources within 

Idaho do not (1) significantly contribute 

to nonattainment of the NAAQS in any 

other state, (2) interfere with 

maintenance of the NAAQS by any 

other state, and (3) interfere with any 

other state’s required measures to 

prevent significant deterioration of its 

air quality, as required by section 

110(a)(2)(D)(i). 

As noted previously, EPA will 

address element (4), interference with 

any other state’s required measures to 

protect visibility, in a separate action. 

EPA will also take action on the portion 

of Idaho’s SIP that addresses the 2006 

PM2.5 NAAQS in a separate action. 

V. Scope of Action 

Idaho has not demonstrated authority 

to implement and enforce IDAPA 

Chapter 58 within ‘‘Indian Country’’ as 


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72718 Federal Register / Vol. 75, No. 227 / Friday, November 26, 2010 / Rules and Regulations 

31 ‘‘Indian country’’ is defined under 18 U.S.C. 

1151 as: (1) All land within the limits of any Indian 

reservation under the jurisdiction of the United 

States Government, notwithstanding the issuance of 

any patent, and including rights-of-way running 

through the reservation, (2) all dependent Indian 

communities within the borders of the United 

States, whether within the original or subsequently 

acquired territory thereof, and whether within or 

without the limits of a State, and (3) all Indian 

allotments, the Indian titles to which have not been 

extinguished, including rights-of-way running 

through the same. Under this definition, EPA treats 

as reservations trust lands validly set aside for the 

use of a Tribe even if the trust lands have not been 

formally designated as a reservation. In Idaho, 

Indian country includes, but is not limited to, the 

Coeur d’Alene Reservation, the Duck Valley 

Reservation, the Reservation of the Kootenai Tribe, 

the Fort Hall Indian Reservation, and the Nez Perce 

Reservation as described in the 1863 Nez Perce 

Treaty. 

defined in 18 U.S.C. 1151.31 Therefore, 

EPA proposes that this SIP approval not 

extend to ‘‘Indian Country’’ in Idaho. See 

CAA sections 110(a)(2)(A) (SIP shall 

include enforceable emission limits), 

110(a)(2)(E)(i) (State must have adequate 

authority under State law to carry out 

SIP), and 172(c)(6) (nonattainment SIPs 

shall include enforceable emission 

limits). This is consistent with EPA’s 

previous approval of Idaho’s PSD 

program, in which EPA specifically 

disapproved the program for sources 

within Indian Reservations in Idaho 

because the State had not shown it had 

authority to regulate such sources. See 

40 CFR 52.683(b). It is also consistent 

with EPA’s approval of Idaho’s title V 

air operating permits program. See 61 

FR 64622, 64623 (December 6, 1996) 

(interim approval does not extend to 

Indian Country); 66 FR 50574, 50575 

(October 4, 2001) (full approval does not 

extend to Indian Country). 

VI. Statutory and Executive Order 

Reviews 

Under the Clean Air Act, the 

Administrator is required to approve a 

SIP submission that complies with the 

provisions of the Act and applicable 

Federal regulations. 42 U.S.C. 7410(k); 

40 CFR 52.02(a). Thus, in reviewing SIP 

submissions, EPA’s role is to approve 

state choices, provided that they meet 

the criteria of the Clean Air Act. 

Accordingly, this action merely 

approves state law as meeting Federal 

requirements and does not impose 

additional requirements beyond those 

imposed by state law. For that reason, 

this action: 

• Is not a ‘‘significant regulatory 

action’’ subject to review by the Office 

of Management and Budget under 

Executive Order 12866 (58 FR 51735, 

October 4, 1993); 

• Does not impose an information 

collection burden under the provisions 

of the Paperwork Reduction Act (44 

U.S.C. 3501 et seq.); 

• Is certified as not having a 

significant economic impact on a 

substantial number of small entities 

under the Regulatory Flexibility Act (5 

U.S.C. 601 et seq.); 

• Does not contain any unfunded 

mandate or significantly or uniquely 

affect small governments, as described 

in the Unfunded Mandates Reform Act 

of 1995 (Pub. L. 104–4); 

• Does not have Federalism 

implications as specified in Executive 

Order 13132 (64 FR 43255, August 10, 

1999); 

• Is not an economically significant 

regulatory action based on health or 

safety risks subject to Executive Order 

13045 (62 FR 19885, April 23, 1997); 

• Is not a significant regulatory action 

subject to Executive Order 13211 (66 FR 

28355, May 22, 2001); 

• Is not subject to requirements of 

Section 12(d) of the National 

Technology Transfer and Advancement 

Act of 1995 (15 U.S.C. 272 note) because 

application of those requirements would 

be inconsistent with the Clean Air Act; 

and 

• Does not provide EPA with the 

discretionary authority to address, as 

appropriate, disproportionate human 

health or environmental effects, using 

practicable and legally permissible 

methods, under Executive Order 12898 

(59 FR 7629, February 16, 1994). 

In addition, this rule does not have 

tribal implications as specified by 

Executive Order 13175 (65 FR 67249, 

November 9, 2000), because the SIP is 

not approved to apply in Indian country 

located in the state, and EPA notes that 

it will not impose substantial direct 

costs on tribal governments or preempt 

tribal law. 

The Congressional Review Act, 5 

U.S.C. 801 et seq., as added by the Small 

Business Regulatory Enforcement 

Fairness Act of 1996, generally provides 

that before a rule may take effect, the 

agency promulgating the rule must 

submit a rule report, which includes a 

copy of the rule, to each House of the 

Congress and to the Comptroller General 

of the United States. EPA will submit a 

report containing this action and other 

required information to the U.S. Senate, 

the U.S. House of Representatives, and 

the Comptroller General of the United 

States prior to publication of the rule in 

the Federal Register. A major rule 

cannot take effect until 60 days after it 

is published in the Federal Register. 

This action is not a ‘‘major rule’’ as 

defined by 5 U.S.C. 804(2). 

Under section 307(b)(1) of the Clean 

Air Act, petitions for judicial review of 

this action must be filed in the United 

States Court of Appeals for the 

appropriate circuit by January 25, 2011. 

Filing a petition for reconsideration by 

the Administrator of this final rule does 

not affect the finality of this action for 

the purposes of judicial review nor does 

it extend the time within which a 

petition for judicial review may be filed, 

and shall not postpone the effectiveness 

of such rule or action. This action may 

not be challenged later in proceedings to 

enforce its requirements. (See section 

307(b)(2).) 

List of Subjects in 40 CFR Part 52 

Environmental protection, Air 

pollution control, Carbon monoxide, 

Incorporation by reference, 

Intergovernmental relations, Lead, 

Nitrogen dioxide, Ozone, Particulate 

matter, Reporting and recordkeeping 

requirements, Sulfur oxides, Volatile 

organic compounds. 

Dated: November 10, 2010. 

Dennis J. McLerran, 

Regional Administrator, Region 10. 

■ 40 CFR part 52 is amended as follows: 

PART 52—[AMENDED] 

■ 1. The authority citation for part 52 

continues to read as follows: 

Authority: 42 U.S.C. 7401 et seq. 

Subpart N—Idaho 

■ 2. The table in § 52.670(e) entitled 

‘‘EPA-Approved Nonregulatory 

Provisions and Quasi-Regulatory 

Measures’’ is amended by adding an 

entry to the end to read as follows: 

§ 52.670 Identification of plan. 

* * * * * 

(e) * * * 


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Federal Register / Vol. 75, No. 227 / Friday, November 26, 2010 / Rules and Regulations 72719 

EPA-APPROVED IDAHO NONREGULATORY PROVISIONS AND QUASI-REGULATORY MEASURES

Name of SIP provision 

Applicable geographic or nonattainment area State 

submittal 

date 

EPA 

approval 

date 

Comments 

*******

Interstate Transport State Implementation Plan, 

May 11, 2010 (see comments).

State-wide ........ 06/28/2010 11/26/2010 [Insert 

page number 

where the document begins] 

For the 1997 8-hour ozone NAAQS 

and the 1997 PM2.5 NAAQS. See 

docket EPA–R10–OAR–2010–0669. 

[FR Doc. 2010–29626 Filed 11–24–10; 8:45 am] 

BILLING CODE 6560–50–P 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Part 52 

[EPA–R10–OAR–2008–0482; FRL–9231–1] 

Approval and Promulgation of 

Implementation Plans; Idaho 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Final rule. 

SUMMARY: EPA is approving numerous 

revisions to the Idaho State 

Implementation Plan that were 

submitted to EPA by the State of Idaho 

on May 22, 2003, April 2, 2004, July 13, 

2005, May 5, 2006, April 16, 2007, May 

12, 2008, and June 8, 2009. The 

revisions were submitted in accordance 

with the requirements of section 110 

and part D of the Clean Air Act 

(hereinafter the Act or CAA). EPA is 

taking no action in this rulemaking on 

a number of submitted rule revisions 

that are unrelated to the purposes of the 

implementation plan. 

DATES: This action is effective on 

December 27, 2010. 

ADDRESSES: Copies of the State’s SIP 

revision and other information 

supporting this action are available for 

inspection at EPA Region 10, Office of 

Air, Waste, and Toxics (AWT–107), 

1200 Sixth Avenue, Suite 900, Seattle, 

Washington 98101. 

FOR FURTHER INFORMATION CONTACT: 

Donna Deneen, EPA Region 10, Office of 

Air, Waste, and Toxics (AWT–107), 

1200 Sixth Avenue, Seattle, Washington 

98101, or at (206) 553–6706. 

SUPPLEMENTARY INFORMATION: 

Throughout this document wherever 

‘‘we’’, ‘‘us’’ or ‘‘our’’ are used, we mean 

EPA. Information is organized as 

follows: 

Table of Contents 

I. Background for This Action 

A. What revisions to the Idaho SIP does 

this action address? 

B. What comments did we receive on our 

proposal for these revisions? 

1. Section 110(l) 

a. Summary of Comments Regarding 

Section 110(l) 

b. EPA Response to Section 110(l)-Related 

Comments 

2. Section 193 

a. Summary of Comments Regarding 

Section 193 

b. EPA Response to Section 193-Related 

Comments 

II. Final Action 

A. Rules To Approve Into the Idaho SIP 

B. Rules on Which No Action Is Taken 

C. Scope of Action 

III. Statutory and Executive Order Reviews 

I. Background for This Action 

Title I of the CAA, as amended by 

Congress in 1990, specifies the general 

requirements for states to submit State 

Implementation Plans (SIPs) to attain 

and/or maintain the National Ambient 

Air Quality Standards (NAAQS) and 

EPA’s actions regarding approval of 

those SIPs. On May 22, 2003, April 2, 

2004, July 13, 2005, May 5, 2006, April 

16, 2007, May 12, 2008, and June 8, 

2009, the Idaho Department of 

Environmental Quality (IDEQ) 

submitted numerous revisions to the SIP 

for the State of Idaho. On March 18, 

2010, EPA solicited public comment on 

a proposal to approve all of the 

revisions submitted by IDEQ, except the 

identified provisions on which EPA 

proposed to take no action. 75 FR 

13058. This final action will update the 

federally approved SIP to reflect 

changes to the Rules for the Control of 

Air Pollution in Idaho (IDAPA 58.01.01) 

that were made by IDEQ and reviewed 

and deemed approvable into the Idaho 

SIP (Code of Federal Regulations part 

52, subpart N). 

A. What revisions to the Idaho SIP does 

this action address? 

Table 1 below identifies each SIP 

submittal addressed in this action, 

including the submittal date, title and 

sections of IDAPA 58.01.01 that are 

revised. The submittals include Idaho’s 

annual incorporation by reference of 

various portions of the Code of Federal 

Regulations (CFR), revised new source 

review (NSR) requirements, revised 

permit to construct exemptions, updates 

and clarifications to the State’s 

permitting program, revisions related to 

the definition of ‘‘regulated air 

pollutant,’’ modified definitions for the 

State’s major and minor source 

permitting programs, procedures for 

transferring permits, clarifications to 

sulfur content of fuels provisions, and 

various editorial changes. The 

submittals also included provisions we 

are taking no action on, including an 

electric generating unit construction 

prohibition, demonstration of 

preconstruction compliance with toxic 

standards, permit fee provisions, appeal 

provisions, provisions relating to Tier 1 

operating permits, facility emissions 

cap, standards of performance of certain 

types of waste incinerators, and various 

definition revisions. More information 

about each SIP submittal, including a 

summary of the submittal and relevant 

background information and analysis 

supporting our action, can be found in 

our proposed approval. 75 FR 13058 

(March 18, 2010). 

TABLE 1—IDEQ SIP SUBMITTALS ADDRESSED IN THIS ACTION

Date of submittal Title (with IDEQ Docket No.) Sections of IDAPA 58.01.01 revised or amended 

05/22/2003 1 ......................... Soil Vapor Extraction (58–0101–0102) ........................... 58.01.01.210. 

2001 IBR of Federal Regulations (58–0101–0103) ........ 58.01.01.008 and 107. 

Hospital/Medical/Infectious Waste Incinerators (58– 

0101–0103).

58.01.01.861. 


srobinson on DSKHWCL6B1PROD with RULES