### ENVIRONMENTAL PROTECTION AGENCY 40 CFRPart52 (EPA-R08-0AR-2009-0282); FRLApproval and Promulgation ofStateImplementation Plan Revisions; StateofNorth Dakota; Air Pollution Control Rules, and Interstate TransportofPollution for the 1997

PM2.5 

### and 8-hourOzone NAAQS: "Significant Contribution to Nonattainment" and "Interferencewith Prevention ofSignificant Deterioration" Requirements

AGENCY: Environmental Protection Agency (EPA). 

### ACTION: Final rule. 

### SUMMARY: The Environmental Protection Agency is approving State Implementation Plan (SIP) revisions submitted by the State ofNorth Dakota on April 6, 2009. Specifically, EPA is approving revisions to the North Dakota air pollution control rules regarding prevention of significant deterioration ofair quality, and partially approving the SIP revision "Interstate Transport ofAir Pollution" addressing the requirements ofClean Air Act section 11O(a)(2)(D)(i) for the 1997 PM2.5 and 8-hour ozoneNational Ambient Air Quality Standards (NAAQS). These revisions, referred to as the Interstate Transport ofAir Pollution SIP, address the requirements of Clean Air Act section 11O(a)(2)(D)(i) for the 1997 8-hour ozone and 1997 PM2.5National Ambient Air Quality Standards (NAAQS). In this action, EPA is approving the North Dakota Interstate Transport SIP provisions that address the requirement ofsection 110(a)(2)(D)(i)(I) that emissions from the state's sources do not "contribute significantly" to nonattainment ofthe 1997 8-hour ozone NAAQS and the 1997 PM2.5NAAQS in any other state. In addition, EPA is approving the provisions ofthis SIP that address the requirement ofsection 110(a)(2)(D)(i)(II) that emissions from the state's sources do not interfere with measures required in the SIP ofany other state under part C ofthe Clean Air Act (CAA) to prevent "significant deterioration ofairquality." EPA will act at a later date onthe North Dakota Interstate Transport SIP provisions that address the remaining two requirements ofsection 110(a)(2)(D)(i), that emissions from the state's sources do not "interfere with maintenance" ofthe 1997 8-hour ozone and 1997 PM2.5 NAAQS in any other state, and do not interfere withmeasures required in the SIP ofany other state to "protectvisibility." This action is being taken under section 110 ofthe Clean Air Act. 

### EFFECTIVE DATE: This final rule is effective [insert date 30 days after publication in the Federal Register]. 

### ADDRESSES: EPA has established a docket for this action under Docket ID No. EPA-R08­ OAR-2007-1032. All documents in the docket are listed onthe www.regulations.gov Web site. Although listed in the index, some information is not publicly available, e.g., Confidential Business Information (CBI) orother information whose disclosure is restricted by statute. Certain othermaterial, such as copyrighted material, is not placed on the Internet and will be publicly available only inhard copy form. Publicly available docket materials are available eitherelectronically through www.regulations.gov, or in hard copy atthe Air Program, Environmental Protection Agency (EPA), Region 8, 1595 Wynkoop Street, Denver, Colorado 80202-1129. EPA requests that ifat all possible, you contactthe individual listed in the 

### FOR FURTHERINFORMATION CONTACT section to view the hard copy ofthe docket. You may view the hard copy ofthe docket Monday through Friday, 8:00 a.m. to 4:00 p.m., excluding Federal holidays. 

### FORFURTHERINFORMATION CONTACT: Domenico Mastrangelo, Air Program, U.S. Environmental ProtectionAgency, Region 8, Mailcode 8P-AR, 1595 Wynkoop Street, Denver, Colorado 80202-1129, (303) 312-6416, mastrangelo.domenico@epa.gov. 

### SUPPLEMENTARY INFORMATION: 2

### Definitions Forthe purpose ofthis document, we are giving meaning to certain words or initials as follows: (i) The words or initials Act or CAAmeanorreferto the Clean Air Act, unless the context indicates otherwise. (ii) The words EPA, we, us or ourmean orreferto the United States Environmental Protection Agency. (iii) The initials SIP mean orrefer to State Implementation Plan. (iv) The words State orNorth Dakotameanthe State ofNorth Dakota, unless the context indicates otherwise. 

### Table ofContents I. Background II. Response to Comments III. Section 110(1) IV. Final Action V. Statutory and Executive Order Reviews 

### I. Background and Purpose In a proposed rule action published March 31, 2010 EPA proposed approval of revisions to the State provisions onthe prevention ofsignificant deterioration (PSD) ofair quality in subsection 33-15-15-01.2 ofthe North DakotaAdministrative Code (NDAC), I and partial approval ofthe North DakotaInterstate Transport ofAir Pollution SIP for the 1997 PM2,5 and 8-hour ozoneNational AmbientAir Quality Standards (NAAQS). The revisions to NDAC subsection 33-15-15-01.2, and the addition to the North Dakota SIP ofsection 7.8, "Interstate

3Transport ofAir Pollution," were adopted bythe State ofNorth Dakota onApril 1, 2009 and submitted to EPA on April 6, 2009. In chapter 33-15-15, NDAC, Prevention ofSignificant Deterioration ofAir Quality, revisions were made to subsection 33-15-15-01.2, Scope. The baseline date for incorporationby reference ofthe federal PSD program set out at 40 CFR 52.21 was updated to August 1,2007. In addition, various administrative corrections and clarifications were made. In ourproposal to approve these revisions, EPA stated that the revisions were made to make the North Dakota PSD program consistent with federal requirements. EPA did not receive comments that persuade the Agency that the revisions are less stringentthan or inconsistent with federal requirements, and thus EPA is approving them intoday's final action. Section 110(a)(2)(D)(i) ofthe CAA requires that a state's SIP must contain adequate provisions prohibiting any source or othertype ofemissions activity within the state from emitting any air pollutant in amounts which will: (l) contribute significantly to nonattainment of the NAAQS in any other state; (2) interfere with maintenance ofthe NAAQS by any other**state~** (3) interfere with any other state's required measures to prevent significant deterioration ofair quality; or (4) interfere with any other state's required measures to protect visibility. In our proposed rule EPA proposed partial approval ofthe North Dakota Interstate Transport ofAir Pollution SIP for the 1997 PM2.5 and 8-hour ozone NAAQS. Specifically, EPA proposed approval ofthe North Dakota SIP sections that addressed the first and third requirements, "significant contribution" and "interference with PSD" ofthe Interstate Transport CAA provisions. EPA will act at a later date on the North Dakota Interstate Transport SIP sections that address the remaining requirements: "interference with maintenance" and "interference with

1EPA notes that in the referenced proposedrule there were references to the revision of"NDAC subsection 33-15­ 4visibility." To assess whetheremissions from North Dakota contribute significantly to downwind nonattainment for the 1997 PM2 .5NAAQS, North Dakota and EPA's technical analysis relied on the results ofCAIRmodeling and onmonitoring data in neighboring downwind states. The CAIRmodeling results indicatedthat the State contribution to the closest nonattainment area was belowthe "significantcontribution" threshold. Monitoring data showedthat in downwind states there were no monitors violating the 1997 24-hour or annual PM2 .5NAAQS. To assess whether emissions from North Dakota contribute significantly to downwind nonattainment for the 1997 8-hour ozone NAAQS, EPA'stechnical analysis relied on EPA's 2006 Guidance, recommending consideration ofavailable EPA modeling conducted in conjunctionwith CAIR,2 or in the absence ofsuch EPA modeling, consideration ofother information such as the amount ofemissions, the geographic location ofviolating areas, meteorological data, orvarious other forms ofinformationthat would be relevant to assessing the likelihood ofsignificant contributionto violations ofthe NAAQS in another state. Consistent with theNOx SIP Call and CAIR, ourtechnical analysis assessed the extent ofozone transport from North Dakota notjustfor areas designated nonattainment, but also for areas in violations oftheNAAQS. Because EPA did not have detailed modeling for North Dakota and nearby downwind states, ourapproach did not rely on a quantitative determination ofNorth Dakota's contribution but on a weight-of-evidence approach using quantitative information such
as North Dakota's distance from areas with monitors showing violations ofthe NAAQS, modeling results outlining wind vectors for regional transport ofozone on high ozone days,
15-01.02"(75 FR 16027). As was clear from the context, the references were the results oftypographical errors. 2 In this action the expression "CAIR" refers to the final rule published in the May 12,2005 Federal Register and entitled "Rule to Reduce Interstate Transport ofFine Particulate Matter and Ozone (Clean Air Interstate Rule); 5CAIRmodeling results for other states, and results ofmodeling studies for the nonattainment
areas specifying the range ofwind directions along which contribution ofozone transport occurred. Given that the assessments for each ofthesepieces ofevidence are not individually definitive oroutcome determinative, EPAconcluded in its proposed action that the various factual andtechnical considerations supported a determination ofno significant contribution from North Dakotaemissions to the ozone nonattainment areas noted above. EPA did notreceive commentsthatpersuade the Agencythatthere is such significant contribution for the 1997 ozone orPM2.5 NAAQS and thus in today's final action EPA is making
a final regulatory determinationthatNorth Dakota's emissions sources do not contribute significantly to violations ofthe 1997 8-hour ozoneNAAQS in any other state. II. Response to Comments EPA received one letter from WildEarth Guardians (WG) and one letter from the Sierra Club commenting onEPA's federal register actionproposing approval ofthe portion ofthe North Dakota Interstate Transport SIP that addresses the "significantcontributionto nonattainment" and PSDrequirements ofCAA Section 11O(a)(2)(D)(i) for the 1997 8-hour
ozone and PM2 .5NAAQS, and specific revisions to the air quality control rules addressed within thatproposal. Inthis section EPAresponds to the significant adverse comments madebythe commenters. CommentNo.1

- WG opposed EPA's approval ofNorth Dakota's revision ofits PSD program, based on several alleged deficiencies in thatprogram. Although WG does not explicitly state it, inthe context ofthis action, which also approves the PSD portion ofthe interstate transport SIP noted above, WG's comments couldbetaken to argue thatthe alleged
Revisions to Acid Rain Program; Revisions to NOx SIP Call; Final Rule" (70 FR 25162). 6deficiencies adversely impact the measures required in other states to prevent significant deterioration ofair quality in such states. To the extent WG makes this argument, EPA responds below. As to the first deficiency, WG noted that the current federally-enforceable version ofthe North DakotaPSD program incorporates 40 CFR 52.21 as it stood on October 1, 2003. WG stated that the PSD program in North Dakota shouldbe amended to reflect the effects ofcourt opinions that vacatedportions ofthat version of52.21. EPA Response

- EPA disagrees with the commenter's argument that the North Dakota SIP does not reflect current requirements. North Dakota's submittal incorporated 40 CFR 52.21
as it stood on August 1, 2007. The August 1,2007 version of40 CFR 52.21 fully reflected the effects offederal court decisions vacating certainportions ofNSRrules promulgated in 2002 and 2003.3 Therefore, EPA believes that the North DakotaPSD program approved by EPA in this action also reflects the effects ofthose decisions and is therefore consistent with federal requirements. EPA agrees with the implicit argument (mentioned above) that certain deficiencies in a state's existing SIP, or in a section 110(a)(2)(D) SIP submission itself, could affect the approvabilityof the section 110(a)(2)(D) SIP submission with respect to the PSD requirement. As provided in EPA's guidance for such SIP submissions for the 1997 8-hour ozone and PM2.5 NAAQS, EPA made recommendations with respect to specific SIP revisions that it anticipated would be appropriate to address in the section 110(a)(2)(D) SIP submissions for these NAAQS, whetherbyreference to other submissions already made or within the same SIP submission. For example, for the requirements ofthe PSD element ofsection 110(a)(2)(D) for these NAAQS,

7EPA indicated that a state's SIP should reflect the current requirements for the implementation of the PSD and nonattainment NSRrequirements for these NAAQS, as a means ofestablishing that the state's SIP would not interfere with measures to prevent significant deterioration in other states. EPA believes that this assessment is fact specific, however, and that the question of whether a state's SIP could cause such interference in another state must be examined on a case by case basis. In this instance, because the North Dakotaprogranl nowtracks the requirements of40 CFR 52.21 as ofAugust 1,2007, WG's concern gives no reason to conclude that the revisions could interfere with the measures required in other states. CommentNo.2

- As anotherpotential defect in the North DakotaPSD program, WG noted that the North Dakota PSD program adds the sentence: "[t]his term does not include effects on integral vistas," to 40 CFR 52.21(b)(29), that is, the definition of"adverse impact on visibility." WG argued that this additional language renders the PSD programless stringentthan federal requirements. EPA Response

- EPA disagrees with WG's comment. Inthis comment, and others, WG appears to believe thatperse any deviation from the language of40 CFR 52.21 is invalid. However, the mininlum federal requirements for state PSD programs are specified in 40 CFR 51.166, not in 52.21.4 One way in which a state PSD program may meetthe requirements of

367 FR 80186 (Dec. 31,2002); 68 FR 61248 (Oct. 23, 2003); New York v. U.S. EPA, 413 F.3d 3 (D.C. Cir. 2005); New York v. EPA, 443 F.3d 880 (D.C. Cir. 2006). 4 "The EPA implements the statutory PSD requirements through two sets ofregulations. At 40 CFR 51.166, EPA has set minimum program requirements for States to follow in preparing, adopting, and submitting a PSD program for inclusion as part ofthe required SIP pursuant to Section 11O(c) ofthe Act. At40 CFR 52.21, EPA has promulgated a Federal PSD program requiring the Administrator's preconstruction review and approval ofmajor new or modified stationary sources in the absence ofan approved State PSD program, and for areas such as Indian Lands and Outer Continental Shelfareas that are outside ofthejurisdiction ofindividual States." 58 FR 31622, 31623 (June 3, 1993). For states that-unlikeNorth Dakota-lack a SIP-approved PSD program, EPA may delegate implementation of52.21 to the state. E.g., 73 FR 53401 (Sept. 16,2008) ("Prior to approval ofMichigan's 851.166 is to adoptby reference the federal PSD program at 52.21, as North Dakotahas here. To detemline whether deviations from 52.21 in the North Dakota PSD program meet federal requirements for a state program, the program isjudged against the minimum federal requirements for a state PSD program given in 51.166. As to the requirements of51.166, section 51.166(0)(1) creates a requirement for visibility impact analysis for new major stationary sources and major modifications. Federal requirements for protection ofvisibility in state SIPs are set out in subpart P ofpart 51. Procedures for the visibility impact analysis required by 51.166(0)(1) are given in 51.307, which, by its placement in subpart P, uses the definition ofthe term "adverse impact on visibility" at 51.301. North Dakota's definition is consistent with the federal definition; in fact, it matches it precisely. In addition, no integral vistas have been identified under section 51.304, so the addition ofthe sentence has no effect. Therefore, EPA disagrees withthe comnlentthat the North Dakota PSD program, by modifying 52.21(b)(29), does not meet federal requirements. CommentNo.3

- As another potential issue, WG noted that the North Dakota PSD program deletes references to NAAQS at 52.21(d), (k)(1), and (v)(2)(iv)(a). WG argued that the references mustbe restored to ensure that the NAAQS apply everywhere and that PSD increments are federal increments. EPA Response

- The cited references are replaced in the North Dakotarules by provisions that apply the state ambient air quality standards for areas withinNorth Dakota'sjurisdiction and that apply the NAAQS elsewhere. As discussed elsewhere in these responses, updates to the state ambient air quality standards, consistent withrevisions to the NAAQS, were submitted by

submitted PSD program, EPA delegated to Michigan (via delegation letter dated September 26, 1988) the authority to issue PSD permits through the Federal PSD rules at 40 CFR 52.21."). 9North Dakotato EPA on April 1,2009. EPA will be acting onthe revision in a separate action. Also, the North Dakota PSD program incorporates 40 CFR 52.21(c), which defines the PSD increments, by reference without modification; therefore, the North Dakota PSD increments are the federal increments. CommentNo.4

- As an additional concern, WG noted thatthe North DakotaPSD program replaces 40 CFR 52.21(h) with different state stack height requirements. WG argued that these requirements mustbe at least as stringent as federal requirements. Implicitly, WG argued that these different stack height requirements would interfere with other states's required PSD measures. EPA Response

- EPA disagrees with this comment. WG did not explain or identify any way in which the state requirements are less stringent than federal requirements. EPA has reviewed the North Dakota state stack height requirements and finds that the requirements are at least as stringent as those in 40 CFR 51.166(h), which specifies the minimum stack height requirements for a state PSD program. Therefore, EPA does not believe that the provision creates a deficiency in the North DakotaPSD program orthat the North Dakota SIP interferes with measures required for prevention ofsignificant deterioration in any other state for purposes ofthe 1997 8-hour ozone and PM2.5 NAAQS. CommentNo.5

- WG further argued that the North DakotaPSD program must include 40 CFR 52.21(1)(1) and mustupdate the reference to Appendix W to part 51 in order to be consistent with current federal law requirements. WG also asserted that the North Dakota guidelines for air quality modeling are unacceptable because they are less stringent than applicable federal requirements. EPA Response

- EPA disagrees with the commenter's assessment on this point. The 10federal requirements for modeling in a PSD program are set out at 40 CFR 51.166(1). The North DakotaPSD provisionthat replaces 52.21(1)(l) is consistent with these requirements. Furthermore, the provision does not specify a particular date for incorporation ofAppendix W; EPA therefore believes no update to the reference is necessary. Finally, 51.166(1) provides for modification or substitution ofmodels in Appendix W on a case-by-case or generic basis with written approval ofthe Administrator. The Administratorhas approved, in writing, use ofthe North Dakota guideline on a generic basis by approving previous submittals ofthe North Dakota PSD program that contained the same provision allowing for use ofthe guideline. Therefore, EPA believes that the North Dakotaprovision is consistent with federal requirements in 51.166(1). CommentNo.6

- WG also identified analyses for visibility as another alleged deficiency in the existing PSD program in North Dakota. WG noted that the state's PSD program requires visibility analysis for new source review to be prepared in accordance with state requirements. WG argued that these requirements are less stringentthan federal requirements, and thatthe provisionmusttherefore be deleted. EPA Response

- EPA disagrees with the commenter's assessment. In this instance, WG did not explain or identify any way in which the state requirements are less stringent than federal requirements. The federal requirements for visibility analysis procedures for new source review in state PSD programs are provided in 40 CFR 51.307. The procedures do not specify a particular method for visibility analysis. EPA has reviewed the North Dakotarequirements for visibility analysis and finds they are consistent with federal requirements. Therefore, this is not a basis for disapproval ofthe North Dakota PSD program revision or the section 110(a)(2)(D) submission. 11CommentNo.7

- WG expressed concern with certain public process provisions in the North Dakota SIP. In particular, WG identified state specific provisions for public participation replacing those at 52.21(q). WG argued that the state should not be allowed to provide "summaries" ofothermaterials it considered in making its permit decisions. 5 WG also argued that the state provisions shouldrequire the Department to respond to relevant comments. EPA Response

- EPA disagrees with the commenter'sview ofthese specific requirements. The minimum federal requirements for public participation in a state PSD program are set out in 51.166(q). The state provision cited by WG is consistent with the requirements at 51.166(q)(2)(ii); in fact, the provision matches 51.166(q)(2)(ii) precisely. Therefore, EPA believes that the North Dakota PSD program meets federal requirements for public participation. As such, this is not a basis for disapproval ofthe North Dakota PSD program revision orthe section 11O(a)(2)(D) submission. CommentNo.8

- WG identified otherprocedural requirements as potential defects in the North Dakota SIP. WG noted that the North Dakota PSD program adds to 52.21(r)(2) the sentence: "[i]n cases ofmajor construction projects involving long lead times and substantial financial commitments, the department may provide by a conditionto the permit to construct a time period greaterthan eighteen months when such time extension is supported by sufficient documentation by the applicant." WG argued that this provision should be removed because it allows major sources to be built with stale determinations ofambient air impacts and best available control technology. EPA Response

- Federal requirements for source obligations in a state PSD program are set out at 51.166(r). This federal regulatory provision does not impose any particular time period

5 The commenter refers to section (g) ofthe provision, but from the mention of"summaries" it appears the 12[orvalidityofa PSDpermit. In addition, 52.21(r)(2) currentlyprovides for extensions beyond the given eighteen-month period, ifan applicant makes a satisfactory showing that an extension lisjustified. Thus, EPAbelieves thatthe stateregulatoryprovision citedbythe commenteris Iconsistent withboth 51.166(r) and 52.21(r)(2). Giventhis conclusion, EPA does not consider this a basis for disapproval ofthe North Dakota PSD program revision orthe section 110(a)(2)(D) submission. CommentNo.9

- WG also opposed EPA's proposed approval ofthe North Dakota section 110(a)(2)(D) SIP submission with respect to PSD requirements for the 1997 8-hour
ozone and PM2.5 NAAQS because the submission did not address other, more recent NAAQS. WGnoted that the current EPA-approved version ofthe North Dakota SIP at NDAC 33-15-02 does not incorporate all current NAAQS, including the 2006 PM2 .5NAAQS, the 2008 ozone NAAQS, and the 2010N02NAAQS. WG stated its concern that the failure to incorporate the latestNAAQS implies that these NAAQS will not be addressed in permitting and planning determinations by the state. EPA Response

- EPA disagrees withthe commenteronthis point. First, in this action, EPA is approving theNorth Dakotainterstate transport SIP for the 1997 8-hour ozone and PM2 .5 NAAQS; EPA is also approving a revision to North Dakota's PSD program. WG does not explain howa failure to incorporate the current NAAQS in the state ambient air quality standards is relevant to EPA's action onthe North Dakotainterstate transport SIP for the 1997 8-hour
ozone and PM2 .5NAAQS. Thus, the comment does not give grounds for disapproval ofthe interstate transport SIP for theNAAQS at issue in this rulemaking.

commenter is referring to section (b). 13Furthermore, as noted in the proposal for this action, EPA has included the revision to North Dakota's PSD program in this action to address an issue specifically mentioned in the 2006 guidance. The guidance recommended that in orderto satisfy the PSD requirement of 110(a)(2)(D)(i), the state's interstate transport SIP, or existing SIP, should meetthe requirements ofthe Phase II implementationrule for the 1997 8-hour ozone NAAQS. In particular, this means the state's SIP should identify NOx as a precursor to ozone, and the SIP revision submitted by North Dakotahas done so. Thus, the current NAAQS are not relevant to this action. Finally, EPA disagrees that approval ofthis SIP submission implies thatNorth Dakota will not take appropriate required actions with respect to other, more recent, NAAQS. Consistent with the requirements ofthe CAA and applicable regulations, EPA expects North Dakotato consider other more recent NAAQS in permitting decisions. As additional SIP revisions are necessary, EPA anticipates that the state will comply, as indeed it has inthis very action with respect to necessary revisions for the 1997 8-hour ozone NAAQS. CommentNo. 10

- WG asserted that EPA's proposed approval was based on a "flawed legal standard." According to WG, EPA erred inthe proposal by explaining that various factual
ortechnical assessments indicate that it is "highly unlikely" that emissions from North Dakota
sources significantly contribute to violations ofthe 1997 8-hour ozone NAAQS, orto violations ofthe 1997 PM2.5NAAQS in other states. WG's position is that EPA cannot approve a SIP submission based upon "unlikelihood" because CAA Section 110(a)(2)(D)(i)(I) prohibits emissions that contribute significantly to nonattainment in other States and does not allow EPA to approve SIPs simplybecause a state's emissions are "unlikely"to contribute significantly to nonattainment.

14EPA Response

- EPA disagrees with WG's characterization ofEPA's analysis and WG's interpretation ofthe statutory requirements. First, EPAnotes thatthe discussion inthe proposal
was intended to presentthe various factual and technical considerations available to assess whetherthere is oris not significant contribution to nonattainment in other states as a result of emissions from North Dakota sources. Giventhat these assessments are not individually definitive oroutcome determinative, EPAbelieves that it is entirely appropriate to present and describe the relative probative value ofthe various considerations accurately. Second, EPA notes that all such technical evaluations are by theirnature subject to some degree ofuncertainty. Indeed, the modeling that WG elsewhere contends should be the sole method for evaluating interstate transport is itselfbut one means ofevaluating the real world impacts ofemissions in light ofmeteorological conditions, wind direction, and other such variables, and produces a result that is itselfsubjectto some degree ofuncertainty. Third, EPAbelieves that it was also appropriate to describe the various factual andtechnical considerations and whetherthey indicated a "likelihood" ofsignificant contribution to nonattainment in another state because the proposal was seeking comment from the public upon whetherthese considerations together supported a determination ofno such significant contribution. EPA did notreceive comments that persuade the Agency that there is such significant contribution, and thus intoday's final action EPA is making a final regulatory determination that North Dakotaemissions sources do not significantly contribute to violations ofthe 1997 8-hour ozone NAAQS, orto violations of the 1997 PM2.5NAAQS in any other state, for the reasons explained elsewhere inthis notice. In other words, EPAhas concluded that the existing SIP for North Dakota already contains adequate provisions to prevent emission from North Dakota sources from significantly

15contributing to violations ofthe 1997 8-hour ozoneNAAQS, or to violations ofthe 1997 PM2.5 NAAQS in other states and is therefore approving North Dakota's submission for this purpose. CommentNo. 11

- WG argued thatNorth Dakota and EPA did not appropriately assess impacts to nonattainment in downwind states. According to WG, North Dakotafailed to assess significance ofdownwind impacts in accordance with EPA guidance and precedent. Although this is unclear from the comment, WG evidently believes that EPA's applicable guidance for this purpose appears only in the 1998 NOx SIP call. WG asserts that, based onthe precedent ofthe NOx SIP Call, the following issues need to be addressed in determining whether ornot an area is significantly contributing to nonattainment in downwind States: (a) the overall nature ofthe
ozone problem; (b) the extent ofdownwind nonattainment problems to which upwind State's emissions are linked; (c) the ambient impact ofthe emissions from upwind States' sources onthe downwind nonattainment problen1s; and (d) the availability ofhigh cost-effective control
measures for upwind emissions. (63 FR 57356-57376, October 27, 1998). EPA Response

- EPA disagrees with WG onthis point. Section 110(a)(2)(D) does not explicitly specify how states orEPA should evaluate the existence of, or extent of, interstate transport and whetherthat interstate transport is ofsufficient magnitude to constitute "significant contributionto nonattainment" as a regulatory matter. The statutory language is ambiguous on its face and EPA must reasonably interpretthat language when it applies it to factual situations before the Agency. EPA agrees thatthe NOx SIP Call is one rulemaking in which EPA evaluated the existence of, and extent of, interstate transport. In that action, EPA developed an approachthat allowed the Agency to evaluate whetherthere was significant contribution to ozone nonattainment across an entire region that was comprised ofmany states. That approach 16included regional scale modeling and othertechnical analyses that EPA deemed useful to evaluate the issue ofinterstate transport onthat geographic scale and for the facts and circunlstances at issue in that rulemaking. EPA does not agree, however, that the approach of 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 evaluatingthe question on a state by state basis, and in situations where there is not evidence ofwidespread interstatetransport. Indeed, EPA issued specific guidance making recommendations to states about howto address section 110(a)(2)(D) in SIP submissions for the 8-hour ozone and PM2.5NAAQS. 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. 6 This guidance documentpostdatedthe NOx SIP Call, and was developed by EPA specifically to address SIP submissions for the 1997 8-hour ozone and PM2.5NAAQS. Within that 2006 guidance document, EPA notes that it explicitly stated its viewthat the "precise nature and contents ofsuch a submission [are] not stipulated in the statute" and that the contents ofthe SIP submission "may vary depending upon the facts and circumstances related to the specific NAAQS.,,7 Moreover, within that guidance, EPA expressed its view that "the data and analytical tools available" at the time ofthe SIP submission "necessarily affect[] the content

6 Memorandum 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-R08-0AR-2007-1032.0004.1. 7Id.at3. 17ofthe required submission."g To that end, EPA specifically recommended that states located within the geographic region covered by the "CleanAir Interstate Rule (CAIR)," comply with section 110(a)(2)(D) for the 1997 8-hour ozone and PM2.5NAAQS by complying with CAIR itself. For states outside the CAIRrule 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 contributionto nonattainment "might include, but is not limited to, information concerning emissions inthe 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 arnbit ofthe CAIR, or such other information as the State considers probative onthe issue ofsignificant contribution.,,9 In addition, EPA recommended that states might electto evaluate significant contributionto nonattainment using relevant considerations comparable to those used by EPA in CAIR, including evaluating impacts as ofan appropriate year (such as 2010) and in light ofthe cost of control to mitigate emissions that resulted in significant contribution. WG did not acknowledge or discuss EPA's actual guidance for section 110(a)(2)(D) SIP submissions for the 1997 8-hour ozone and PM2 .5NAAQS, and thus it is unclear whether WG
was aware ofit. In any event, EPA believes that the North Dakota submission and EPA's evaluation ofit was consistent with EPA's guidance for the 1997 8-hourozone and PM2 .5 NAAQS. For example, as discussed in the proposal notice, the State and EPAconsidered information such as monitoring data inNorth Dakota and downwind states, geographical and meteorological information, and technical studies ofthe nature and sources ofnonattainment

18rroblems in various downwind states. These are amongthe types ofinformationthat EPA recommended and that EPA considers relevant. Thus, EPA has concluded that the state's submission, and EPA's evaluation ofthat submission, meet the requirements ofsection 110(a)(2)(D) and are consistentwith applicable guidance. Finally, EPA notes that the considerations the Agency recommended to States in the 2006 Guidance document are consistent with the concepts that WG enumerated from the NOx SIP Call context: (a) the overall nature ofthe ozone problem; (b) the extent ofdownwind nonattainmentproblems to which upwind State's emissions are linked; (c) the ambient impact of the emissions from upwind States' sources onthe downwind nonattainment problems; and (d) the availability ofhigh cost-effective control measures for upwind emissions. The only distinction inthe case ofthe North Dakota submission at issue here would be that because the available evidence indicates that there is very little contribution from emissions from North Dakota sources to nonattainment in other states, it is not necessary to advance to the final step and evaluate whetherthe cost ofcontrols for those sources is above or below a certain cost of control as part ofdetermining whether the contribution constitutes "significant contributionto nonattainment" for regulatory purposes, as was necessary in the NOx SIP Call and in CAIR. CommentNo. 

### 12

- WG argued that EPA's assessment that North Dakota will not significantlycontribute to nonattainment ofthe ozone NAAQS in**do~wind** States is based primarily onmodeling prepared in conjunction with CAIR, and yet "EPA admits that CAIR only addressed PM2.5impacts." EPA Response

- EPA agrees with WG that CAIRevaluated only PM2.5 impacts for North Dakota. However, EPA disagrees that the CAIR ozone modeling results are irrelevantto this

9 ld. at 5. 19action: as the NPR made clear, it is actually the CAIR modeling analyses for ozone transport from Minnesota-notNorth Dakota-thatEPA considered as evidence in this action. 10 Furthermore, we do notthink that within the proposed rule ofMarch 31, 2010, EPA suggested that the assessment ofimpacts from NorthDakota's emissions to nonattainment ofthe ozone NAAQS in downwind States was based primarily onmodeling prepared in conjunction with CAIR. Instead, EPA made clearthat the CAIR modeling analysis results for Minnesota, considered in combination with emissions levels in Minnesota and North Dakota, and their respective distances from the Illinois/Wisconsin nonattainment counties, was only one piece of relevant evidence in EPA's weight-of-evidence determination. The comment seems to reflect a misreading ofour proposed nLle action, or a misinterpretation ofone ofthe pieces ofevidence in
ourtechnical analysis. Thus, EPA does not see in its proposedrule the contradiction alleged by this comment. CommentNo. 

### 13

- WG reiterated its concern that the North Dakota section 11O(a)(2)(D) submission was deficient because it did not strictly follow WG's summary ofthe structure ofthe analysis ofinterstate transport in the NOx SIP Call: (a) the overall nature ofthe ozone problem; (b) the extent ofdownwind nonattainment problems to which upwind State's emissions are

10 SpecificalJy, the relevant portion ofourproposed rule reads: "The CAIR modeling domain for 8-hourozone transport analysis included only the eastern halfofNorth Dakota, and the CAIRmodeling analysis did not determine whether NOx emissions from North Dakota sources contributed significantly to ozone nonattainment in any downwind states. However, the CAIR modeling analysis results for Minnesota provide us the opportunity to draw inferences about ozone contribution from North Dakota sourcesto nonattainment in the Illinois/Wisconsin area. It must be noted that Minnesota is nearly halfas distant from this nonattainment area as North Dakota (400 miles as compared with 700), and that to reach the Illinois/Wisconsin nonattainment area, ozone transport winds from Minnesotawould have to have a northwesterly orientation similarto that necessary for substantial ozone transport from North Dakota. In addition, the CAIRmodeling analysis estimated the Minnesota's NOx emissions for the 2010 base year to be approximately twice as large as the NOx emissions from North Dakota's sources (381,500 as compared with 182,800 tons.) FinalJy, the CAIR analysis determined that emissions from Minnesota were below the initial threshold for including states in CAIR. In light ofthis CAIR determination, and ofMinnesota's larger NOx emissions and shorter distance to the nonattainment area, it is plausible to conclude that NOx emissions from North Dakota sources are not likely to contribute significantly to nonattainment ofthe 1997 8-hour ozone standard in the Illinois and Wisconsin counties along the southwestern shores ofLake Michigan." 75 FR 16030. 20linked; (c) the ambient impact ofthe emissions from upwind States' sources on the downwind nonattainment problems; and (d) the availability ofhigh cost-effective control measures for upwind emissions. EPA Response

- EPA disagrees with WG's view that any analysis ofinterstate transport must follow a specific formulaic structure to be approvable. As noted above, EPA issued specific guidance to states making recommendations for section IIO(a)(2)(D) SIP submissions for the 1997 8-hour ozone and PM2.5NAAQS. Within that guidance, EPA recommended various types ofinformation that states might wish to consider in the process ofevaluating whether their
sources contributed significantly to nonattainment in other states. EPA has concluded that the submission from North Dakota, augmented by EPA's own analysis, sufficiently establishes that North Dakota sources do not significantly contribute to violations ofthe 1997 8-hour ozone and PM2.5NAAQS in other states. As noted above, EPA believes that the state's submission, and EPA's analysis ofit, address the same conceptual considerations that the commenter advocated. CommentNo. 

### 14

- WG asserted that North Dakota and EPA provided "no analysis" of the contribution from North Dakotato downwind states and no "actual assessment" ofthe significance ofany such contribution. EPA Response

- EPA disagrees with WG'sposition. WG again assumes that section 110(a)(2)(D) explicitly requires the type ofmodeling analysis thatthe commenter advocates throughout its comments. Because WG apparently views the NOx SIP Call as the applicable guidance, WG contends that any analytical approach that.is not identical to that approach is impermissible. Inaddition, WG overlooks the fact that in other actions based upon section IIO(a)(2)(D), EPA has also used a variety ofanalytical approaches, short ofmodeling, to evaluate whether specific states are significantly contributing to violations ofthe NAAQS in 21another state (e.g., the west coast states that EPA concluded should not be part ofthe geographic region ofthe CAIRrule based upon qualitative factors, and not by the zero out modeling EPA deemed necessary for some other states). In the proposed approval, EPA explainedthat otherfonns ofavailable information were sufficientto make the determination that there is no significant contribution from North Dakota
sources to downwind nonattainment ofthe 1997 8-hour ozone NAAQS. As stated in the proposal: "EPA'sevaluation ofwhether emissions from North Dakota contribute significantly to the ozone nonattainmentinthese areas is based on an examination ofhow geographical and meteorological factors affect transport from North Dakotato the two
areas noted above. Our approach does not rely on a quantitative detennination ofNorth Dakota's contribution, as EPA did for other states in its CAIRrulemaking, but on a weight-of-evidence analysis based onqualitative assessments and estimates ofthe relevant factors. While conclusions reached for each ofthe factors considered in the following analysis are not in and by themselves detenninative, consideration ofthe likely effect ofall factors provides a reliable qualitative conclusion on whetherNorth Dakota's emissions are likely to contribute significantly to nonattainment in the DMA/NFR area and the Illinois/Wisconsin Counties. 11 EPA acknowledged that the various fonns ofinformation considered in the proposal (such as distance, orientation ofsurface and regional transport winds, back trajectory analyses, monitoring data) were not individually outcome detenninative, but concludedthat when taken together served to establish that North Dakota sources do not significantly contribute to



### 22downwind nonattainment ofthe 1997 8-hour ozone NAAQS in other states. Thus, contrary to WG's assertion, EPA did perform an "analysis" and an "assessment" that was areasonable basis for its conclusion that emissions from North Dakota do not contribute significantly to downwind
ozone nonattainment, using a combination ofquantitative data and qualitative analyses. EPA does not agree that only the type ofanalysis advocated byWG could adequately evaluate the issue and support a rational determination in this instance. CommentNo. 

### 15

- WG objectedto EPA'sproposed approval because North Dakota assessed impacts in downwind states by considering monitoring data in those states as a means ofevaluating significant contribution to nonattainment. In other words, WG is concerned that North Dakota did not assess impacts in areas that have no monitor. WG likewise objected to EPA's "endorsement" ofthis approach. WG argued that this reliance on monitor data is inconsistent with both section 110(a)(2)(D) and with EPA's guidance, by which the commenter evidently means the NOx SIP Call. In support ofthis assertion, WG quoted from the NOx SIP Call proposal in which EPA addressed the proper interpretation ofthe statutory phrase "contribute significantly to nonattainment:" "The EPA proposes to interpretthis term to refer to air quality and notto be limited to currently-designated nonattainment areas. Section 11O(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 inthe context ofthe 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
1175 FR 16030. 23quality" inthese 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 pointthat EPA was making in quoted statement from the NOx SIP Call proposal (and that EPA has subsequently made in the context ofCAIR). When EPA stated that it would evaluate impacts on air quality in downwind states, independent ofthe current formal "designation" of such downwind states, it was not referring to air quality in the absence ofmonitor data. EPA's point was that it was inappropriate to wait for either initial designations ofnonattainment for a
newNAAQS under section 107(d)(1), or for a redesignation to nonattainment for an existing NAAQS under section 107(d)(3), before EPAcould assess whether there is significant contributionto nonattainment ofa NAAQS in another state. For example, in the case ofinitial designations, section 107(d) contemplates a process and timeline for initial designations that could well extend for two or three years following the promulgation ofa new or revised NAAQS. By contrast, section 11O(a)(1) requires states to make SIP submissions that address section 11O(a)(2)(D) and interstate transport "within 3 years
or such shorterperiod as the Administrator may prescribe" ofEPA'spromulgation ofanew or revised NAAQS. This schedule does not support a reading ofsection 11O(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 CAIRrulemaking. WG's misunderstanding ofEPA's statement concerning designation status evidently caused WGto believe that EPA's assessment ofinterstate transport in the NOx SIP Call was not limited to evaluation ofdownwind areas with monitors. This is simply incorrect. In both the 24NOx SIP Call and CAIR, EPA evaluated significant contributionto nonattainment as measured
or predicted at monitors. For example, in the technical analysis for the NOx SIP Call, EPA specifically evaluated the impacts ofemissions from upwind states on monitors located in downwind states. The NOx SIP Call did not evaluate impacts at points without monitors, nor did the CAIRrulemaking. EPA believes that this approach to evaluating significant contribution is correctunder section 110(a)(2)(D), and EPA's general approachto this threshold determination has not been disturbed by the courts. 12 Finally, EPA disagrees with WG's argument that the assessment ofsignificant contributionto downwind nonattainment must include evaluation ofimpacts on non-monitored
areas. First, neither section 11O(a)(2)(D)(i)(I) provisions, nor the EPA guidance issued for the 1997 8-hour ozone NAAQS on August 15, 2006 support WG's position, as neitherrefers to any requirement or recommendation to assess air quality in non-monitored areas. 13 The same focus
on monitored data as a means ofassessing interstate transport is found in the NOx SIP Call and in CAIR. An initial step in both theNOx SIP Call and CAIR was the identification ofareas with current monitored violations ofthe ozone and/or PM2.5NAAQS. 14 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 evaluatedthe presence and extent ofinterstate

12 Michigan v. U.S. EPA, 213 F.3d 663,674-681 (D.C. CiT. 2000); North Carolina v. EPA, 531 F.3d 896, 913-916 (D.C. Cir. 2008) (upholding EPA approach to detennining threshold despite remanding other aspects ofCAIR). 13 2006 Guidance, p. 5. 14 "Based on this approach, we predicted that in the absence ofadditional control measures, 47 counties with air qualitymonitors [emphasis ours] would violate the 8-hour ozone NAAQS in 2010
...." From the CAIR proposed rule ofJanuary 30, 2004 (69 FR4566,4581). The NOx SIP call proposed rule action reads: "
...For current nonattainment areas, EPA used air quality data for the period 1993 through 1995 to detennine which counties are violating the I-hour and/or 8-hourNAAQS. These are the most recent 3years offully quality assured data which were available in time for this assessment," 62 FR 60336. 25

# ~ransport under section 110(a)(2)(D) by focusing on monitoring data. Indeed, such monitoring 

### I datawas atthe core ofboth ofthese efforts. In neitherofthese rulemakings did EPA evaluate significantcontribution to nonattainment in areas in which there was no monitor. This is reasonable and appropriate, because data from a properly placed federal reference method monitor is the way in which EPA ascertains thatthere is a violation ofthe 1997 8-hour ozone or PM2.5 NAAQS in a particular area. Put another way, in orderfor 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 ofthatNAAQS. EPA has concluded that by considering data from monitored areas, its assessment ofwhether emissions from North Dakota contribute significantly to ozone or PM2 .5nonattainment in downwind States is consistent with the 2006 Guidance, and with the approach used by both the CAIRrule and the NOx SIP Call. CommentNo. 

### 16

- In support ofits comments that EPA should assess significant contributionto nonattainment in nonmonitored areas, WG argued that existing modeling performed by another organization "indicates that large areas ofneighboring states will likely violate the ozone NAAQS." According to WG, these likely "violations" ofthe 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 ofOzone Performance in WRAP Modeling and Relevant to Future Regional Ozone Planning"). WG asserted that: "Slide 28 ofthis presentation displays projected4th highest 8-hour ozone reading for 2018 and indicates that air quality throughout large portions ofthe West will exceed and/or violate the 1997 ozone NAAQS
....".15 In short, WG argues that modeling performed by the WRAP establishes that there will be violations ofthe 1997 8-hour ozone NAAQS in 2018 in non-monitored areas Western states.

26EPA Response

- EPA disagrees withthis comment on several grounds. First, as explained in response to other comments, EPA does not agree that it is appropriate to evaluate significantcontributionto 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 ofthe 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 otherrulemakings under section 110(a)(2)(D), and EPA'sprior analytical approach has notbeen disturbed by the courts. Second, WG's own description ofthe ozone concentrations predicted for the year 2018 as projecting "violations" ofthe 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 ofthe 4th max above the NAAQS only constitutes an exceedance oftheNAAQS; to constitute a violation ofthe 1997 8-hour ozone NAAQS, the standard mustbe exceeded for three consecutive years atthe same monitor. Thus, even ifthe WRAP presentation submitted by WG were technically sound, the conclusion drawn from it by WG is inaccurate and does not support its claim ofprojected violations ofthe NAAQS in western States south and west ofNorth Dakota. EPA has also reviewed the WRAP presentation submitted by WG, and believes thatthere
was a substantial error in the WRAP modeling software that led to overestimation ofground level ozone concentrations. A recent study conducted by Environ for the FourComers Air Quality Task Force (FCAQTF; Stoeckenius et aI., 2009) has demonstrated that excessive vertical transport in the CMAQ and CAMx models overhigh terrain was responsible for overestimated

15 The presentation is available for review as Document ID # EPA-R08-0AR-2007-1032-0007.8 at Regulations.gov, 27ground level ozone concentrations due to downward transport ofstratospheric ozone, 16 Environ has developed revised vertical velocity algorithms in a new version ofCAMxthat eliminatedthe excessive downward transport ofozone from the top layers ofthe model. This revised version of the model is nowbeing used in a number ofapplications throughout high terrain areas in the West. Inconclusion, EPAbelievesthat this key inadequacy ofthe WRAP model, noted above, makes it inappropriate support for WG's concerns about large expanses of8-hour ozone nonattainment areas projected for 2018 in areas without monitors. Finally, it must be noted that even ifthe ozone exceedances predicted for the year 2018
were based ona sound modeling analysis, even the closest areas showing exceedances are several hundred miles southwest ofNorth Dakota and, as indicated in ourproposed rule, the northeasterly winds required for ozone transport from North Dakotato these areas are a rarity (75 FR 16030). CommentNo. 

### 17

- As additional support for its assertion that EPA should require modeling to assess ambient levels inunmonitored portions ofother States, WG relied on an additional study entitledthe "Uinta Basin Air Quality Study (UBAQS)." The commenter argued that the UBAQS study further supports its concern that limiting the evaluation ofdownwind impacts only to areas withmonitors fails to assess ozone nonattainment in non-monitored areas. According to the commenter, UBAQS modeling results showthat: (a) the Wasatch front region is currently exceeding and will exceed in 2012 the 1997 8-hour ozone NAAQS; and (b) based on

Docket ID # EPA-R08-0AR-2009-0282. 16 Stoeckenius, 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. 282005 meteorological data, portions ofthe four counties in the southwest corner ofUtah are also currently in nonattainment and will be in nonattainment in 2012. 17 

### EP A 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 aboutthe need to evaluatethe possibility of significant contributionto nonattainment in non-monitored areas. EPA sees several problems withthe commenter's interpretation ofthe UBAQS analysis results for counties in Utah's southwestern corner: "based on 2005 meteorological data, portions ofWashington, Iron, Kane, and Garfield Counties are also in nonattainment and will be in nonattainment in 2012." First, WG's interpretation ofthe predicted ozone concentrations shown in Figures 4-3a and 4-3b (pages 5 and 6 ofthe comment letter) is inaccurate. A close review ofthe legend in these figures indicates that the highest ozone concentrations predicted bythe model for portions ofthe counties noted above are somewhere between 81.00 and 85.99 ppb, but a specific concentration is not provided. Ifthe ozone concentration is actually predicted to be smallerthan
orequal to 84.9 ppb, then the area is attaining; ifitis predicted as greaterthan 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 bothbe in attainment orboth in nonattainment, or
one ofthem in attainment and the other in nonattainment, for the 1997 8-hour ozone NAAQS. Second, even ifthe design values predicted for these unmonitored area were at the top of the 81.00-85.99 ppb range, their reliability would remain questionable. The UBAQS itself

17 The southwestern areareferred to by the commenter includes portions ofWashington, Iron, Kane, and Garfield 29identifies and illustrates major shortcomings ofits modeling analysis, only to neglect assessing the impact ofthese shortcomings onthe modeling results.I8 The study deviates in at leasttwo significantways from EPA's 2007 guidance on SIP modeling. 19 One issue is the UBAQS modeling reliance on fewer than the five years ofdatarecommended by EPA to generate a current 8-hour ozone design value (DVC). UBAQS relaxed this requirement so that sites with as little as 

### 1year ofdatawere included as DVCs in the analysis. The other issue is the computation ofthe relative responsive factor (RRF), which directly affects the modeling's future design value (DVF).20 Again due to unavailability ofdata satisfying EPA'srecommendation that the RRF be based on a minimum offive days ofozone concentrations above 85 ppb, UBAQS modeling uses RRFs based on one or more days ofozone concentrations above 70 ppb.21 EPA concludes that the modeling analysis results used bythe WG are umeliable for projecting non-attainment status and therefore do not support its comments. Finally, the predicted attainment status ofunmonitored areas in the southwestern corner ofUtah is notrelevant to our assessment ofwhetheremissions from North Dakotacontribute significantly to downwind ozone nonattainment. The counties identified that drawthe commenter's attention are almost a 1,000 miles from Bismarck, North Dakota, in a southwestern direction. As indicated in ourresponse to the previous comment, the northeasterly winds required for ozone transport from North Dakotato these areas are a rarity. CommentNo. 

### 18

- In support ofits arguments that EPA should not limit assessment of

Counties. 18 See "UBAQS," pages 4-27 to 4-29. 19 EPA. 2007. Guidance on the Use ofModels and otherAnalyses for Demonstrating Attainment ofAir Quality Goals for Ozone, PM2.5 and Regional Haze. Office ofAir Quality Planning and Standards, Air Modeling Group. Research Triangle Park, North Carolina (http://www.epa.gov/scramOOl/guidance/guide/final-03-pm-rh­ guidance.pdf). 20 DVC x RRF = DVF. 21 See UBAQS, p. 4-28 30Isignificant contribution to nonattainment through evaluation ofimpacts at monitors, but include, [through modeling analysis, impacts where there are no such monitors, the commentercited apast 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 03 monitors, while many large midwestern 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 evaluation ofsignificant contributionto nonattainment in other states relying on monitoring data instead of modeling ambient levels. The comment also indicates that States with few or no non-urban monitors include "Idaho, Nebraska, Nevada, Montana, and Oregon, which may be affected by North Dakota emissions." EPA Response

- EPA does not disagree that there are relatively few monitors in the western states, and that relatively few monitors are currently located innon-urban areas of western states. However, the commenter failed to note thatthe quoted statement from EPA concerning the adequacy ofwestern monitors came from the Agency'sJuly 16,2009proposed rulemaking entitled "Ambient Ozone Monitoring Regulations: Revisions to Network Design Requirements." This statement was thus taken out ofcontext, because EPA was in thatproposal referring to changes in state monitoring networks that it anticipates will be necessary inorderto implement not [emphasis added] the 1997 8-hour ozone NAAQS that are the subject ofthis rulemaking, butrather the next iteration ofthe ozoneNAAQS for which there are concerns that there will be a need to evaluate ambient levels in previously unmonitored areas ofthe western United States. The fact that additional monitors may be necessary in the future for newer ozone NAAQS does not automatically meanthat the existing ozone monitoring networks are 31insufficient for the 1997 8-hour ozoneNAAQS, as the commenter implies. Indeed, states submit annual monitor network reports to EPA and EPA evaluates these to insure thatthey meetthe applicable requirements. Forexample, North Dakota itselfsubmitsjust such a report on an annual basis, and EPAreviews it for adequacy.22 All other states submit comparable reports. Finally, EPA disagrees that monitored and unmonitored areas inthe western States identified above bythe commenter may be affected by emissions from NorthDakota. As noted in the proposed rule, the easterly ornortheasterly winds that would be needed to transport emissions from North Dakotato these States are rare?3 Similarly rare is the possibility of impacts onthese States from North Dakota's emissions. CommentNo. 

### 19

- WG objected to EPA'sproposed approval ofthe North Dakota SIP submissionbecause neitherNorth DakotanorEPAperformed a specific modeling analysis to
assure that emissions from North Dakota sources do not significantly contribute to nonattainment in downwind States. According to the commenter, EPA's decision to use a qualitative approach to determine whetheremissions from North Dakota contribute significantly to downwind nonattainment is not consistent with its ownpreparation ofa regional model to evaluate such impacts from other states as part ofCAIR. EPA Response

- EPA disagrees with WG's beliefthat only modeling can establish whether ornotthere is significant contribution from one state to another. First, as noted above, EPA does not believe that section 110(a)(2)(D) requires modeling. While modeling can be useful, EPA believes that otherforms ofanalysis canbe sufficient to evaluate whether ornot there is significant contributionto nonattainment. Forthis reason, EPA's 2006 Guidance

22 See, for example: "Annual Report. North Dakota Air Quality Monitoring, Data Summary, 2008." dated June 2009, North Dakota Department ofHealth. A is available for review atthe regulations.gov web site, under Docket ID No EPA-R08-0AR-2009-0282. 32recommended other forms ofinformation that states might wish to evaluate as part oftheir section 110(a)(2)(D) subnlissions for the 1997 8-hour ozone NAAQS. EPA has concluded that its qualitative approachto the assessment ofsignificant contribution to downwind ozone nonattainment is consistent with EPA's 2006 Guidance. Second, EPA notes that WG'sposition also reflects a misunderstanding ofthe approach EPA used inthe remanded CAIRdue to WG's exclusive focus onthose States that were selected for the modeling analysis. A wider understanding ofthe CAIRapproach would recognize that EPA decided, based on other criteria, that it was not necessary to conduct modeling for certain western states: "[i]n analyzing significant contribution to nonattainment, we determined it was reasonable to exclude the Western U.S., including the States ofWashington, Idaho, Oregon, California, Nevada, Utah, and Arizonafrom further analysis due to geography, meteorology, and topography. Based onthese factors we concluded that the PM2.5 and 8-hour ozone nonattainment problems are not likely to be affected significantly by pollutiontransported across these States' boundaries
...." (69 FR4581, January 30, 2004). EPA has taken a similar approach to assess whetherNorth Dakota contributes significantly to violations ofthe 1997 8-hour ozone and PM2 .5NAAQS in downwind states. In the proposed action, EPA explained several forms ofsubstantive and technically valid evidence that led to the conclusion that emissions from North Dakota sources do not contribute significantly to nonattainment, in accordance with the requirement ofSection 110(a)(2)(D). CommentNo. 20

- In further support ofits argumentthat EPA must use modeling to evaluate whetherthere is significant contribution to nonattainment under section 110(a)(2)(D), WG noted that EPA itselfasks other agencies to perform such modeling in other contexts. As

23 See our assessment ofozone transport from North Dakota emissions to Colorado, 75 FR 16030. 33examples, the commenter cited four examples in which EPA commented on action s by other agencies in which EPArecommended the use ofmodeling 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 ofoil and gas development projects.24 WG questioned why EPA's recommendation for such an approach in its comments to other Federal Agencies, did notresult in its use ofthe same approach to evaluate the impacts from North Dakotaemissions and to insure compliance with Section 11O(a)(2)(D)(i)(I). The commenterreasoned that the emissions that would result from the actions at issue inthe other agency decisions, such as selected oil and gas drilling projects, would be ofless magnitude and importance thanthe statewide emissions at issue in an evaluation under section 11O(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, whetherby section 110(a)(2)(D), by EPA guidance, orbypastEPAprecedent. EPA's applicable guidance made recommendations as to different approaches that can lead to the satisfaction ofthe interstate transportrequirements for significant contributionto nonattainment in other states. EvenEPA's own CAIR analysis relied on a combination ofqualitative and quantitative analyses,
as explained above. As indicated in ourresponse to CommentNo. 19, the CAIR analysis excluded the Western States onthe based on a qualitative assessment ofthe regions topography, geography and meteorology.25

24 WG's April 9, 2010 comment letter, pp. 9-10. Complete versions ofthe EPA comment letters referenced here were attached to the comment as Exhibits 3 through 6, and are viewable on the Regulations.gov web site as Documents ID No. EPA-R08-0AR-2007-1032-0007,4 through 1032-0007.7. 25 See: 69 FR4581 ,January 30, 2004. 34EPA believes that the commenter's references to EPA statements comnlenting onthe actions ofother agencies are inapposite. As WG is aware, those comments were made inthe context ofthe evaluation ofthe impacts ofvarious federal actions pursuant to NEPA, notthe CleanAir Act. As explained above, in the context ofsection 110(a)(2)(D), EPA does not agree that modeling is always required to make that different evaluation, and EPA itselfhas relied on other more qualitative evidence when it deemed that evidence sufficientto reach a reasoned determination. CommentNo. 21

- In further support ofits argument that EPA should always require modeling to evaluate significant contributionto nonattainment, WGreferred to EPA regulations governing nonattainment SIPs. The commenternoted 40 CFR 51.112(a)(l), which states that: "[t]he adequacy ofa control strategy shall be demonstrated by means ofapplicable air quality models, databases, and otherrequirements specified in appendix W of[Part 51] (Guideline on Air Quality Models)." The commenter argues that this regulation appears to support the commenter'sposition that modeling is required to satisfy the significant contribution element of 110(a)(2)(D). EPA Response

- EPA disagrees withthis comment. The cited language implies thatthe need for control strategy requirements has already been demonstrated, and sets a modeling analysis requirement to demonstrate the adequacy ofthe control strategy developed to achieve the reductions necessary to prevent an area's air quality from continuing to violate the NAAQS. EPA's determinationthat emissions from North Dakotado 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 satisfyingthe section 110(a)(2)(D) requirements. Moreover, EPA interprets the language at40 CFR 51.112(a): "[e]achplan must demonstrate that the measures, 35rules, and regulations contained in it are adequate to provide for the timely attainment and maintenance ofthe national standard that it implements," to refer to modeling for attainment demonstrations, an integral part ofnonattainment area SIPs under part D ofthe CAA. This interpretation was upheld by the Sixth Circuit Court ofAppeals. Wall 

### v. Us. EPA, 265 F.3d 426,436 (6th Cir. 2001). Thus, the comnlenter's cited regulation is not relevant to EPA's technical demonstration assessing whether emissions from North Dakotacontribute significantly to nonattainment in any other states under section 110(a)(2)(D). CommentNo. 22

- WG also objectedto EPA'sproposed approval ofthe North Dakota submission onthe grounds that it was based upon a "weight-of-evidence analysis," and that no such weight ofevidence 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-ofevidence" approach to assessing air quality impacts. The commenter asserted that EPA neither cited nor quoted regulations orpolicy that provides for this, and failed to lend any specific nleaning to the phrase through its proposed approval. Finally, the commenter asserted, without explaining, its beliefthat EPA failed to address "several relevant factors related to the determination ofwhetherNorth Dakotacontributes 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 ofevidence." 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 contributionto nonattainment in other states. Through past actions such as CAIR, EPA has used a weight-of-evidence approach to exclude some States from further 36consideration.26 As described above, EPA's guidance issued for the 1997 8-hour ozone NAAQS, the Agency specifically recommended types ofinformation 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 ofevidence approach that properly considers appropriate evidence is sufficient to make a valid determination, as in this case. Specifically, EPA's technical analysis in the March 31,2010proposed rule action underscores its reliance on implementationpolicies set inthe 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 ornot its emissions significantly contribute to violations ofthe 1997 ozone standards in another state. Among other methods, EPA recommended consideration ofavailable 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 violatingareas, meteorologicaldata, or various other forms of information thatwouldbe relevant to assessing the likelihoodof significant contribution to violations of the NAAQS in another state [our emphasisl,,27 Onthe basis ofthis guidance, North Dakota and EPA chose to assess the impacts ofemissions from North Dakota sources on the closest downwind nonattainment areas (Denver, Colorado, and Illinois/Wisconsin counties along the southwestern shore ofLake Michigan) through a weight ofevidence approach using quantitative information such as North Dakota's distance from areas with monitors showing violation ofthe NAAQS, modeling results outlining wind vectors for regional transport ofozone
on high ozone days, backtrajectory analyses for the downwind nonattainment areas closestto North Dakota, and results ofmodeling studies for the nonattainment areas specifying the range

26 See: 69 FR4581, January 30, 2004. 37ofwind directions along which contributing ozone transport occurred. EPA's use ofa weight of evidence analysis is by no means unusual for the assessment ofozone impacts through long range transport. The same analytical framework was used inthe 1998 NOx SIP Call, as indicated under Section II.C., entitled "Weight-of-Evidence Determination ofCovered States.,,28 The differences between the specific types ofevidence used in the NOx SIP Call and in our analysis do not invalidatethe use ofthe 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 specifythe characteristics, including limitations, ofa weight ofevidence analysis: "[f]urthermore
...EPA notes that no single piece ofinformation in the following discussion is by itselfdispositive ofthe issue. Instead, the total weight ofall the evidence takentogether supports the conclusionthat emissions from North Dakota sources are unlikely to contribute significantly to violations ofthe 1997 8-hour ozone standard in any other state," (75 FR 16034). Finally, as to the commenter's assertion that EPA failed to consider "several relevant factors" and thus failed to conduct an appropriate weight ofevidence evaluation, EPA cannot weigh the validity ofthis comment in the absence ofan explanation ofwhat these factors might be. CommentNo. 23 - The Sierra Club opposed the proposed approval on the grounds that the existing North Dakota SIP includes problematic provisions. Forexample, the Sierra Club pointedto provisions that it alleges will result in additional emissions that could significantly contribute to nonattainment ofthe NAAQS in other states. Forexample, Sierra Club argued that:

27 75 FR 16029, March 31, 2010. 28 "As discussed above, EPA applied a multi-factor approach to identify the amounts ofNOx emissions that contribute significantly to nonattainment
...." 1998 SIP Call, 63 FR 57381, October 27, 1998. 38"ifemissionviolations during startup, shutdown, ormalfunctions (SSM) escape enforcement, there is no way to determine that emissions from sources inNorth Dakota will not contribute significantlyto other States' nonattainment ofthe NAAQS orproblems with PSD compliance such as exceeding increments, short ofcumulative modeling exercise assuming that all source
are emitting at theirphysical limits without controls. See, e.g., CleanAirAct Sections 110(a)(2)(A) and (D), 42 U.S.C. Sections 7410(a)(2)(A) and (D).,,29 

### EPA Response

- EPAunderstands the concerns raised by the commenter, butdoes not believe that any such excess emissions would in and ofthemselves constitute significant contribution to nonattainment in another state. EPA notes that its technical analysis for the significant contribution element in ourproposal was not premised upon distinguishing between legal and illegal, orpermissible and impermissible, emissions from NorthDakota sources. EPA's technical analysis, and the conclusionbased onthe weight ofthe evidence, did not depend
onthe precise amount ofemissions from NorthDakota, and did nottumupon someportion of those emissions as being the result ofemissions during SSMevents. Instead, EPA's evaluation
was focused upon otherrelevant informationthat pertained to distance, wind direction, and the air quality status ofareas in downwind states. Thus, any additional emissions from SSMevents would not change the analysis or EPA's conclusionthat emissions from North Dakotado not significantly contributeto nonattainment in any other state.

29 "Ifemission violations are excused during startups, shutdowns, ormalfunctions, and thus essentially unregulated during those periods, there is no way to detennine that emissions from sources in North Dakota will not contribute significantly to other States' nonattainment ofthe NAAQS orproblems with PSD compliance such as exceeding increments, adversely impacting air quality related values in Class I areas, or adversely impacting vegetation and visibility in all areas, short ofcumulative modeling exercise assuming that all source are emitting at theirphysical limits without controls. See, e.g., CleanAirAct Sections 11O(a)(2)(A) and (D), 42 V.S.c. Sections 741O(a)(2)(A) and (D)." 39Furthermore, as noted below, the current version ofthe North Dakotaprovision relating to SSM, NDAC 33-15-01-13, does not create any exemption from emissions limits and does not
excuse violations. PSD permit applicants and PSD permittees in North Dakota are subjectto the current version ofthe state's regulation. Therefore, Sierra Club's concerns regarding excess emissions from sources subjectto PSD are moot and do not change EPA's conclusionthat the North Dakota SIP has adequate provisions to prohibit emissions from North Dakota from interfering with other states' required PSD programs. 

### CommentNo 24

- As potential SIP defects affecting approvability ofthe section 110(a)(2)(D) SIP submission, both WG and the Sierra Club pointed to the North Dakota Administrative Code rule NDAC 33-15-01-07 that allows the North Dakota Department of Health (NDDH) to grant variances to emission limits ifcompliance "would cause undue hardship, would be unreasonable, impractical, or not feasible underthe circumstances." WG adds that this variance provision is inappropriate and would allow additional emissions that may contribute significantly to nonattainment or interfere with PSD provisions in other States. 

### EP AResponse

- EPA agrees that this rule should be revised to provide that variances are only effective for federal lawpurposes when adopted as a SIP revision approved by EPA (or this provision should be removed from the SIP), and EPA plans to work with the State to clarify the SIP onthis point. EPA is aware that this process requires action by the North Dakota legislature before the NDDH will be able to remove the Variance provisions from the State SIP and submit an appropriate revision to EPA. However, EPA does not believe that this existing variance provision provides a basis for disapproval ofthe SIP under the facts and circumstances here. North Dakota has informed EPA thatthe variances granted by the NDDH under the provision during the last 15 years were only
40for open burning requests. In these cases, before granting a variance the NDDH requested input from the local fire department and health agency offices. North Dakotahas stated that the variance provision cannotbe used to avoid permitting requirements or to violate emissions limits. Furthermore, North Dakotahas confirmed that the provisionhas notbeen applied to PSD permits, minorNSRpermits, Title V permits, or minor operating permits, and EPA expects that such will be the case while it vigorously works withthe State for its removal from the North Dakota SIP. Moreover, EPA also disagrees with WG's additional comment that this variance provision specifically allows emissions that may contribute significantly to nonattainment or interfere with PSD provisions in other States. There is no language inrule NDAC 33-15-01-07 thatreflects the commenter's interpretation. Given the limited scope andusage ofthe variance provision, EPA concludes that it does not constitute interference with other states' required PSD programs. Furthermore, it does not affect EPA's factual determination that emissions from North Dakotado not significantly contributeto nonattainment in other states. CommentNo. 25

- WG also expressed concernthat NDAC 33-15-01-13(1) specifically allows a sourceto shut down air pollution control equipment for maintenance and to continue operations, so long as notification is provided to North Dakota. WG argued that such an exemption to pollution control equipment is not acceptable under the CAA. EPA Response

- EPAbelieves that the commenter is referring to provisions in the previous version ofthe provisionthat is no longer operative. The provision has been superseded by arevision adopted bythe State on April 1, 2009 and submitted to EPA on April 6, 2009. EPA is planning to take action onthe submission inthe near future. The revised
41NDAC 33-15-01-13.1 includes at 33-15-01-13(l)(f) language that addresses the commenter's
concern: "[n]othing in this subsection shall in any manner be construed as authorizing or legalizing the emissions ofair contaminants in excess ofthe rate allowed by this article [NDAC 33-15] ora permit issued pursuant to this article." As noted above, North Dakotahas revised the provision and it currently is in effect. Thus, even before EPAtakes action on the submittal ofthe revision, PSD permit applicants and PSD permittees must comply with the revised provision, which removes the exemption. North Dakotahas confirmed that the revised provision is used in PSD permitting. Therefore, EPA believes that the superseded provision does not constitute interference with other states' required PSD measures. Furthermore, the provision-regardless ofits status-doesnot affect EPA's factual determination that emissions from North Dakota do not significantly contribute to nonattainment in other states. CommentNo. 26

- WG also argued that Rule NDAC 33-15-01-13(2) implies an exemption to compliance with emission limits in the event ofa malfunction. According to the commenter, this rule not only implies an exemption for malfunction leading to a violation that lasts less than 24 hours, but gives the state unlimited discretion to allow a malfunction leading to
a violation to last as long as ten days. EPA Response

- EPA again disagrees, because the commenteris evidently objecting to a previous version ofthis provisionthat is no longer operative. The provision was superseded by a revision to this rule adopted by the State on April 1, 2009 and submitted to EPA on April 6, 2009. EPA plans to take action on the submission in the near future. Under the revised provision the ten-day grace period has been removed, and the provisions only address notification requirements without any references to orexemptions ofexcess emissions. 42North Dakota has revised the provision and it is no longer in effect. Thus, even before EPAtakes action onthe submittal ofthe revision, PSD permit applicants and PSD permittees must comply with the revised provision, whichremoves the ten-day grace period. Therefore, EPA believes that the superseded provision does not constitute interference with other states' required PSD measures. Furthermore, the provision-regardless ofits status--does not affect EPA's factual determination that emissions from North Dakota do not significantly contribute to nonattainment in other states. CommentNo. 27

- The Sierra Club expressed concernthat the revised version ofNDAC 33-15-01-13(2)(c) submitted by the state to EPA "does not make clearthat such enforcement discretion is limited to the imposition ofcivil penalties and does not potentially enable sources to avoid injunctive remedies regarding excess emissions." The Sierra Club also indicated that in the revised language ofrule NDAC 33-15-01-13(2)(c) "therequired elements ofproofin the source's report fall short ofthe rigorous proofrequirements specified in EPApolicy." EPA Response -Asnoted above, the State submitted the referenced revisions to EPA on April 6, 2009, and the public, including the Sierra Club, will have an opportunity to submit substantive comments aboutthis provision when EPA proposes action on it, as planned for the
near future. EPA invites the Sierra Club to resubmit the comment at thattime so that EPA may properly respond to it. EPA notes, however, that the Sierra Club appears to argue that certain portions ofthe 1999 EPA guidance for the affirmative defense approach to unavoidable malfunctions30 apply to the North Dakotarevision. As stated in that guidance, the enforcement

30 Memorandwn from Steven A. Herman, Assistant Administratorfor Enforcement and Compliance Assurance, and Robert Perciasepe, Assistant Administrator for Air and Radiation, "State Implementation Plans: Policy Regarding Excess Emissions During Malfunctions, Startup, and Shutdown" (Sept. 20, 1999). 43discretion approach endorsed by EPA in earlier guidance3! remains valid, and North Dakota selected the enforcement discretion approach. In any event, EPA is not acting uponthat April 6, 2009, submission at this time. CommentNo. 28 - WG and the Sierra Club also expressed concern about a provision in the North Dakota SIP related to failure ofa continuous emission monitoring system (CEMS). See NDAC § 33-15-01-13(3). WG and the Sierra Club both argued thatthe provision is contrary to Title IV ofthe CAA and the regulations at 40 CFR Part 75 implementing Title IV. WG apparently believed that EPA cannot approve the North Dakota SIP section 110(a)(2)(D) revision until the provision is removed or revised. EPA Response: EPA disagrees with WG's conclusions on this issue. As to the significant contribution element of 110(a)(2)(D)(i), as noted above, once EPA has determinedas it has here-thatemissions from North Dakota do not significantly contribute to nonattainment in any other state, no substantive modification ofNorth Dakota's SIP is required to eliminate any emissions. As to the PSD element of 110(a)(2)(D)(i), the requirements ofPart 75 relate to Title IV, the acid rain title ofthe Clean Air Act. These requirements are simply not relevant to the North Dakota PSD program orto the PSD element of 110(a)(2)(D)(i). CommentNo. 29: As part ofits objectionto the proposed action, the Sierra Club identified a North Dakota SIP provisionthat authorizes North Dakotato allowviolations of ambient air quality standards in certain circumstances. See NDAC 

### § 33-15-02-07(4). EPA Response

- EPA disagrees that this provisionprovides a basis for disapproval ofthe section 110(a)(2)(D) submission. The provision does allow for certain exceedances ofcertain

31 See Memorandum from Kathleen M. Bennett, Assistant Administrator for Air, Noise, and Radiation, "Policy on Excess Emissions During Startup, Shutdown, Maintenance, and Malfunctions" (Sept. 28, 1982); Memorandum from Kathleen M. Bennett, Assistant Administrator for Air, Noise, and Radiation, "Policy on Excess Emissions During 44state ambient air quality standards. However, it does not allowfor exceedances ofthe applicable federal NAAQS. Therefore, EPA concludes thatthe provision does not constitute interference with other states' required PSD programs. Furthennore, the provision does not affect EPA's factual detennination that emissions from North Dakotado not significantly contribute to nonattainment in other states CommentNo. 30

- WG also identified certain provisions in the North Dakota SIP creating exceptions to certain opacity limits as a concern in the context ofaction on the section 110(a)(2)(D) submission. See NDAC 

### § 33-15-03-04(4), (5). WG described the provisions as "blanketexemptions" and argued that because visible emissions are often used as an indicator for particulate matter, the exemptions "fail to prohibit emissions that could contribute significantly to nonattainment or interfere with PSD requirements." WG therefore argued that EPA cannot approve the proposed SIP revision unless the exemptions are removed or revised. EPA Response

- EPA does not endorse the exceptions cited by WG, and EPA's action here should not be construed as an approval ofthese exceptions, which are not the subject ofthis action. EPA disagrees, however, with WG's conclusions about the impact ofsuch exceptions on today's action. First, the exceptions are not "blanket exemptions" from all opacity limits: by the express tenns ofNDAC 33-15-03-04, the exceptions apply only to the numeric opacity limits specified inNDAC 33-15-03-01, -02, -03, and -04. They do not create an exception from any requirements PSD may impose related to opacity. Furthennore, the specific numeric opacity limits are unrelated to emissions limits imposedby PSD, under which BACT is detennined on a case-by-case basis. Thus, the provisions cited by WG do not create any exception from BACTemissions limits orany other Startup, Shutdown, Maintenance, and Malfunctions" (Feb. 15, 1983) (clarifying 1982 memorandum). 45PSD requirements. As a result, the exceptions are notrelevant to the requirements ofthe PSD element of 110(a)(2)(D)(i). As to the significant contribution element of 110(a)(2)(D)(i), as noted elsewhere, once EPAhas factually determined-as it has here-that emissions from North Dakotado not significantly contribute to nonattainment in any other state, no modification of North Dakota's SIP is required. 

### CommentNo. 31

- As additional problematic provisions in the North Dakota SIP, WG and Sierra Club identified provisions in the North Dakota SIP creating exceptions to certain particulate matter emissions limits. 

### See NDAC § 33-15-05-01(2)(a). WG argued thatthe provisions allowthe state discretion to exempt sources from compliance during temporary breakdowns or cleaning ofair pollution control equipment, and that therefore the North Dakota SIP fails to prohibit emissions that contribute significantlyto nonattainment in other states, or that interfere with other states' required PSD measures. Sierra Club argued thatthe provision violates EPApolicy and creates a broader exception than allowed by the enforcement discretion
or affirmative defense approaches to unavoidable malfunctions. 

### EP AResponse

- EPA does not endorse the exceptions cited bythe commenters, which EPA notes are notthe subject ofthis action. EPAdisagrees, however, with the commenters' conclusions. First, as to PSD requirements: the provision cited by the commenters creates an exception only to numeric, process-based emissions limits specified in Table 3 ofNDAC 33-15­ 05-01. Theprovision does not create an exception from any PSD requirements, including BACT emissions limits for particulate matter. Furthermore, these specific, numeric, process-based limits
are unrelated to PSD requirements, under which BACT is determined on a case-by-case basis. Thus, the exceptions in 33-15-05-01(2)(a) do not create any exception from BACT emissions limits orother PSD requirements. As a result, the exceptions are not relevantto the requirements 46ofthe PSD element of 110(a)(2)(D)(i). As to the significant contribution element of 110(a)(2)(D)(i), EPA disagrees with WG that EPA cannot approve the North Dakotainterstate transport SIP until the provision is removed
orrevised. As noted elsewhere, once EPA has determined-as ithas here-that emissions from North Dakotado not significantly contribute to nonattainment in any other state, no modification ofNorth Dakota's SIP is required. CommentNo. 32 - The Sierra Club commented on a provisioninthe North Dakota SIP related to reporting ofexcess emissions ofsulfur dioxide and other sulfurcompounds. See NDAC § 33-15-06-05. The Sierra Club asserted that the provision "contains unacceptable language" and argued the SIP should be revised to make clearthat the reporting requirement does not authorize orexempt excess emissions. Sierra Club also impliedthatthis issue makes it impossible to determine whether emissions from North Dakota significantly contribute to nonattainment in other states and whetherthe state's SIP would interfere with measures required in other states to prevent significant deterioration ofair quality withrepect to the 1997 8-hour
ozone and PM2.5NAAQS. EPA Response

- The Sierra Club did not identify any particularphrase inthe existing regulatory provision as unacceptable, so EPApresumes the reference to unacceptable language is to the absence ofadditional clarifying language. EPA disagrees that it is necessary to revise the provision in orderto approve the North**Dakot~** interstatetransport SIP. The provision does not create any explicit exemption, and EPAbelieves it creates no implicit exemption. As the Sierra Club agrees, the provision simply requires sources to report excess emissions ofsulfur dioxide and other sulfur compounds during periods ofstartup, shutdown, and malfunction. A reporting requirement is not an exemption from emissions limits. 47CommentNo. 33

- WG objectedto EPA's proposed approval because "NorthDakota's SIP, as written, simply does not contain any language that literally prohibits emissions that contribute significantly to nonattainment in any other state." The commenter also notes that EPA did not assess whetherthe SIP does or does not contain suchprovisions. The commenter appears to believe that 11O(a)(2)(D)(i) requires a state SIP to contain explicitprovisions literally prohibiting emissions that contribute significantly to nonattainment in any other state, and that, in orderto approve theNorth Dakota interstate transport SIP, EPA must examine the SIP to determine whether it does contain such specific words. EPA Response

- EPA disagrees withthe commenter's interpretation ofthe statutory requirements. Section 11O(a)(2)(D)(i) has no language that requires a SIP to contain literal provisions prohibiting significant contributionto nonattainment in any other state, or, for that matter, to contain any particular words or generic prohibitions. Instead, EPAbelieves thatthe statute requires a state's SIP to contain substantive emission limits orotherprovisions that in fact
ensure that sources located withinthe state will notproduce emissions that have such an effect in other states. Therefore, EPAbelieves that satisfaction ofthe "significantcontribution" requirement is notto be demonstratedthrough a literal requirement for a prohibition ofthe type advocated by the commenter. EPA's past application ofsection 11O(a)(2)(D) did notrequire the literal prohibition advocated bythe commenter. Forexample, in 1998 NOx SIP call (63 FR 57356, October 27, 1998) EPA indicatedthat "theterm 'prohibit' means that SIPs must eliminatethose amounts of emissions determinedto contribute significantly to nonattainment.
..." As a result, the first step ofthe process to determine whetherthis statutory requirement is satisfied is the factual determination ofwhether a state's emissions contribute significantlyto nonattainment in 48downwind areas. See 2005 CAIR Rule (70 FR 25162) and 1998 NOx SIP Call (63 FR 57356). Ifthis factual finding is in the negative, as is the case for EPA's assessment ofthe contribution from emissions from North Dakota, 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, orat its own election, throughparticipation in a cap and trade program. Thus, EPA's approach in this action is consistent with the Agency's interpretation of 1IO(a)(2)(D)(i) in the 2006 guidance, the CAIR Rule, and the NOx SIP call,
none ofwhich required thepro forma literal "prohibition" ofthe type advocated bythe commenter. CommentNo. 34

- WG argues that the requirements for stationary source permitting in the North Dakota SIP are "riddled with vagueness, discretion, uncertainty, and unenforceability," and are inadequate to ensure that sources inNorth Dakota will not significantly contribute to nonattainment in other states. EP A Response

- As discussed above, the first step ofthe process to determine whether the "significantcontribution" requirement is satisfied is the factual determination ofwhether a State's emissions contribute significantly to nonattainment in downwind areas. Ifthe factual finding is in the negative, as is the case for EPA's assessment ofthe contribution from emissions from North Dakota, then section 1IO(a)(2)(D)(i)(I) does not require any changes to a state's provisions. As discussed above, EPA's approach in this action is consistent with the Agency's interpretation of 110(a)(2)(D)(i) in the 2006 guidance, the CAIRRule and the NOx SIP Call. Therefore, EPA disagrees with the commentthat EPA cannot approve the North Dakota 

### 49interstate transport SIP unless EPA addresses specific provisions and state guidelines for permitting stationary sources. CommentNo. 

### 35

- The commenter argued that EPA cannot approve the section 110(a)(2)(D) submission from North Dakotabecause the state and EPA did not comply with 110(1). Evidently, the commenterbelieves that the section 110(a)(2)(D) submission is a revision to the SIP that will interfere with attainment ofthe 2006 PM2.5NAAQS and the 2008 ozone NAAQS. And, although it is not clear, the comment could be taken to make the same point for North Dakota's revision ofits PSD program. The commenter argues that a section 110(1) analysis must consider all NAAQS once they are promulgated, and argues that EPA took the
same position in proposing to disapprove a PM10 maintenance plan. EPA Response

- EPA agrees that a required section 110(1) analysis must considerthe potential impact ofaproposed SIP revision on attainment and maintenance ofall NAAQS that
are in effect and impacted by a given SIP revision. However, EPA disagrees that it failed to comply with the requirements ofsection 110(1) orthat section 110(1) requires disapproval ofthe SIP submission at issue here. Section 110(1) provides in part that: "[t]he Administrator shall not approve a revision ofa plan ifthe revision would interfere with any applicable requirement concerning attainment and reasonable further progress ..., or any other applicable requirement ofthis chapter." EPA has consistently interpreted Section 110(1) as not requiring a new attainment demonstration for every SIP submission. EPA has further concluded that preservation ofthe 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 58,199, 58,134 (Oct. 5. 2005); 70 FR 17.029, 17,033 (Apr. 4, 2005); 70 FR53, 57 (Jan. 3, 2005); 70 FR28,429, 28,431 50(May 18, 2005). North Dakota's submission is the initial submission by the state to address the significant contribution to nonattainment element of 110(a)(2)(D)(i) for the 1997 8-hour ozone and PM2.5 NAAQS. 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 PM2.5NAAQS. 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 ofthe North Dakota interstate transport SIP will not interfere with attainment ormaintenance ofany NAAQS. As to the PSD program, the North Dakota revision updates the incorporation date of40 CFR 52.21 from October 1,2003,to August 1,2007. The changes to 52.21 in that period do not relax any PSD requirements. In fact, the primary substantive change was the recognition ofNOx
as a precursorto ozone, a change that strengthens PSD requirements. Other changes included (as noted elsewhere in EPA's response to comments) recognition ofthe effects offederal cases vacating certain aspects ofNSRrules promulgated in 2002 and 2003.32 These changes do not relax any PSD requirements and in most instances strengthenthem. Therefore, approval ofthe revision ofthe North Dakota PSD program will not interfere with attainment ormaintenance of theNAAQS. EPA's discussion in the notice citedby the commenter is consistent with this interpretation. In the cited action, EPA noted that "Utah ha.[d] either removed or altered a number ofstationary source requirements," creating the possibility ofa relaxation ofSIP requirements interfering with attainment, a possibility that is not present here. See 74 FR62727

51(Dec. 1, 2009). Thus, the action cited bythe commenter is clearly distinguishable. The commenter did notprovide any specific basis for concludingthat approval ofthis SIP submission would interfere with attainment or maintenance ofa NAAQS, orwith any other applicable requirement ofthe Clean Air Act. EPA concludes that approval ofthe submission will not make the status quo air quality worse, and is in fact consistent withthe development of
an overall plan capable ofmeeting the Act's attainment requirements. Accordingly, even assuming that section 110(1) applies to this submission, EPA finds that approval ofthe submission is consistentwith the requirements ofsection 110(1). III. Section 110(1) Section 110(1) ofthe Clean AirAct states that a SIP revision cannotbe approved ifthe revision would interfere with any applicable requirement concerning attainment and reasonable further progress towards attainment ofthe NAAQS or any other applicable requirements ofthe Act. In this action, EPA is approving theportions ofthe North Dakotainterstate transport SIP that address the "significantcontribution" and PSD elements ofsection 110(a)(2)(D)(i) for the 1997 8-hour ozone and PM2 .5NAAQS; EPA is also approving a revision to the North Dakota PSD program. As discussed above in EPA'sresponse to comments, the portions ofthe interstate transport SIP that EPA is approving do notrevise orremove any existing emissions limit for any NAAQS, or any other existing substantive SIP provisions relevantto the 1997 8-hour ozone and PM2.5NAAQS. Furthermore, as also discussed above, the revision to the North DakotaPSD program does notrelax orremove any PSD requirement and in most cases strengthens those requirements. As a result, the SIP revision does notrelax any existing requirements or alterthe status quo air quality. Finally, EPA has determined thatthe revision is consistent with all

32 67 FR 80186 (Dec. 31, 2002); 68 FR 61248 (Oct. 23, 2003); New York v. U.S. EPA, 413 F.3d 3 (D.C. Cir. 2005); 52applicable federal requirements and will not interfere with requirements ofthe Act related to administrative orprocedural provisions. Therefore, the revision does not interfere with attainment or maintenance ofthe NAAQS orother applicable requirements ofthe Act. IV. Final Action The Environmental Protection Agency is approving portions ofthe Interstate Transport of Air Pollution SIP submitted by the State ofNorth DakotaonApril 6, 2009. Specifically, inthis action EPA is approving: (a) the introductory language in the State SIP Section 7.8; (b) the "Overview" language in subsectionA., Section 7.8.1; (c) the language in Section 7.8.1, subsection B., "Nonattainment and Maintenance Area Impact," that specifically addresses element (l) ofsection 110(a)(2)(D)(i), the requirementthatthe SIP contain adequate provisions prohibiting emissions from North Dakotafrom contributing significantly to nonattainment in any other state; and (d) Section 7.8.1, subsection C, "Impact on Prevention ofSignificant Deterioration (PSD)." As part ofthis action EPA is also approving revisions to the prevention of significant deteriorationprovisions in subsection 33-15-15 ofthe NDAC. EPA has concluded that the State's submission, and additional evidence evaluated by EPA, establish that emissions from North Dakota sources do not significantly contribute to nonattainment ofthe 1997 8-hour ozone orthe 1997 PM2.5NAAQS in any other state. Therefore, the State's SIP does not need to include additional substantive controls to reduce emissions for purposes ofsection 110(a)(2)(D)(i)(I) for these NAAQS. In addition, EPA has concludedthat with the specific revisions addressed in this action, the State's SIP now contains adequate provisions to prevent emissions from the State's sources from interfering with measures required in the SIP ofany other state underpart C ofthe CAAto prevent "significant

New York v. EPA, 443 F.3d 880 (D.C. Cir. 2006). 53deterioration ofair quality," in accordance with section 110(a)(2)(D)(i)(II). 

### V. Statutory and Executive OrderReview Underthe Clean Air Act, the Administrator is required to approve a SIP submission that complies withthe provisions ofthe Act and applicable Federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, inreviewing SIP submissions, EPA's role is to approve state choices, provided that they meet the criteria ofthe Clean AirAct. Accordingly, this action merely approves state law as meeting Federal requirements and does not impose additional requirements beyond those imposed by state law. Forthatreason, this action:
• Is not a "significantregulatory action" subject to review by the Office ofManagement and Budgetunder Executive Order 12866 (58 FR 51735, October 4, 1993);
• Does not impose an information collectionburden under the provisions ofthe Paperwork Reduction Act (44 U.S.C. 3501 

### etseq.);
• Is certified as not having a significant economic impact on a substantial number ofsmall entities under the Regulatory Flexibility Act (5 U.S.C. 601 

### etseq.);
• Does not contain any unfunded mandate or significantly oruniquely affect small governments, as described in the Unfunded Mandates Reform Act of 1995 (Public Law 104-4);
• Does not have Federalism implications as specified in Executive Order 13132 (64 FR 43255, August 10, 1999);
• Is not an economically significantregulatory action based on health or safety risks subject to Executive Order 13045 (62 FR 19885, April 23, 1997);
• Is not a significantregulatory action subjectto Executive Order 13211 (66 FR28355, May 22, 2001); 54• is not subject to requirements ofSection 12(d) ofthe National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 note) because application ofthose requirements would be inconsistent with the Clean AirAct; and
• Does not provide EPA with the discretionary authority to address, as appropriate, disproportionate human health orenvironmental effects, using practicable and legally permissible methods, under Executive Order 12898 (59 FR7629, 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 orpreempttribal law. The Congressional Review Act, 5 U.S.C. 801 

### etseq., 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 ofthe rule, to each House ofthe Congress and to the Comptroller General ofthe United States. EPA will submit a report containing this action and otherrequired information to the U.S. Senate, the U.S. House ofRepresentatives, and the Comptroller General ofthe United States priorto publication ofthe rule in the Federal Register. A major nL1e cannot take effect until 60 days after it is published in the Federal Register. This action is not a "majorrule" as defined by 5 U.S.C. 804(2). Under section 307(b)(1) ofthe Clean AirAct, petitions forjudicial review ofthis action must be filed in the United States Court ofAppeals for the appropriate circuit by [FEDERAL REGISTER OFFICE: insert date 60 days from date ofpublication ofthis document in the Federal Register]. Filing a petition for reconsideration by the Administrator ofthis final rule 55IDENTIFICATION OF DOCUMENT: Approval and Promulgation ofState Implementation Plan Revisions; State ofNorth Dakota; Air Pollution Control Rules, and Interstate Transport ofPollution for the 1997 

### PM2.5 and 8-hour Ozone NAAQS: "Significant Contribution to Nonattainment" and "Interference with Prevention of Significant Deterioration" Requirements. Final Rule. (EPA-R08-0AR-2007-0645) Page 56 of

# 54{)I( does not affect the finality ofthis action for the purposes of judicial review nor does it extend the time within which a petition forjudicial review may be filed, and shall not postpone the effectiveness ofsuch rule or action. This action may not be challenged later in proceedings to enforce its requirements. (See section 307(b)(2).) List ofSubjects 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. Authority: 42 U.S.c. 7401 et seq.

### ~::t I kIp

# ~--- Dated Regional Administrator Region 8

5640 CFRpart 52 is amended as follows: PART 52 [AMENDED] 1. The authority citationfor Part 52 continues to read as follows: Authority: 42 U.S.C. 7401 et seq. Subpart JJ-North Dakota 2. Section 52.1820 is amended to read as follows:
a. In the table in paragraph (c) by revising the entry for "33-15-15-01.2." b. In the table in paragraph (e) by revising the entry in 

### "(1)" and adding entry "(21)" innumerical orderto read as follows: § 52.2170 Identification ofplan. 

## * * * * * (c)

## *** STATE OF NORTH DAKOTA REGULATIONS

State citation Title/subject State effective date EPA approval date and citationl Explanations


## * * * * 33-15-15-01.2 

## * * Scope 

## * 4/1/09 [Insert Federal Register date of publication] , [Insert Federal Register page number where the

1In orderto determine the EPA effective date for a specific provision listed in this table, consult the Federal Register notice cited in this column for the particularprovision. 57document begins.] 

## * * * * * * *

(e) 

## ***

Name of Applicable State EPA approval Explanations nonregulatory SIP geographic or submittal date and provision non-attainment area date/ adopted date citation4 (l) Implementation Plan for the Control ofAir Pollution for the State ofNorth Dakota. Chapters: 1. Introduction 2. Legal Authority 3. Control Strategy 4. Compliance Schedule 5. Prevention ofAir Pollution Emergency Episodes 7. Review ofNew Sources and Modifications 8. Source Surveillance 9. Resources 10. Intergovernmental Cooperation 11. Rules and Regulations With subsequent revisions to the chapters as follows: Statewide Submitted: 1/24/72 Adopted: 1/24/72 Clarification subn1itted: 6/14/73 2/19/74 6/26/74 11/21/74 4/23/75 5/31/72, 37 FR 10842

With all clarifications: 3/2/76, 41 FR 8956 Excluding subsequent revisions, as follows: Chapters 1, 2, 6, 7, 9, 11, and 12; Sections 2.11, 3.7,6.8,6.10, 6.11,6.13,7.7, and 8.3; portions ofsubsection 7.8.1.B., subsections 7.8.1.D., and 8.3.1. Revisions to these nonregulatory provisions have subsequently been approved. See below.

58

## * * * * * * *

In order to determIne the EPA effectIve date for a specIfic proVIsIon hsted In thIS table, consult (21) Section 7.8, Interstate Transport ofAir Pollution (only 7.8.I.A., portions of7.8.l.B., and 7.8.I.C., see explanation.) Statewide
..... Submitted: 4/09/09 Adopted: 4/01/09 [insert date of FR publication] [insert FRpage number where document begins] Includes Section 7.8, subsection Portions of7.8.1 as indicated below: 7.8.I.A, "Overview,"the language of Subsection 7.8.I.B., "Nonattainment and Maintenance Area Impact," that specifically addresses the "significant contribution to nonattainment" requirement of CAA Section 1IO(a)(2)(D)(i), and all of 7.8.l.C. 4­ 

### .. the Federal Register notice cited inthis column for the particularprovision.

59