### ENVIRONMENTAL PROTECTION AGENCY 40 CFR Part 52 EPA-R06-0AR-2007-0993; FRL- -l 

### Approval and Promulgation ofImplementation Plans; New Mexico; Interstate Transport ofPollution

AGENCY: Environmental ProtectionAgency (EPA).

ACTION: Final rule.

SUMMARY: EPA is approving a portion ofa State ImplementationPlan (SIP) submitted by the State ofNew Mexico for the purpose of addressing the "goodneighbor" provisions ofthe Clean Air Act (CAA) section 11O(a)(2)(D)(i) for the 1997 ozone National Ambient Air Quality Standard (NAAQS) and the 1997 PM 2.5

### NAAQS. This SIP revision satisfies a portion ofthe State ofNew Mexico's obligationto submit a SIP that demonstrates that adequate provisions are in place to prohibit air emissions from adversely affecting another state's air quality through interstate transport. This rulemaking action is being taken under section 110 ofthe CAA and addresses one element ofCAA section 110 (a)(2)(D)(i), which pertains to prohibiting air pollutant emissions from within New Mexico from contributing significantly to nonattainment of the 1997 8-hour ozone and PM 2.5

### NAAQS in any other state.

DATES: This final rule will be effective [Insert date 30 days from date ofpublication in the Federal Register].2 ADDRESSES: EPA has established a docket for this action under Docket IdentificationNo. EPA-R06-0AR-2007-0993. All documents in the docket are listed at 

### www.regulations.gov. Although listed in the index, some information is not publicly available, e.g., Confidential Business Information or other information whose disclosure is restricted by statute. Certain other material, such as copyrighted material, is not placed on the Internet and will be publicly available only in hard copy form. Publicly available docket materials are available either electronically through www.regulations.gov or in hard copy at the Air Planning Section (6PD-L), Environmental Protection Agency, 1445 Ross Avenue, Suite 700, Dallas, Texas 75202-2733. The file will be made available by appointment for public inspection in the Region 6 Freedom of Information Act (FOIA) Review Room betweenthe hours of8:30am and 4:30pm weekdays exceptfor legal holidays. Contactthe person listed in the FOR FURTHERINFORMATION CONTACT paragraph below or Mr. Bill Deese at 214-665-7253 to make an appointment. If possible, please make the appointment at least two working days in advance ofyour visit. There will 

### be a 15 cent per page fee for making photocopies ofdocuments. On the day ofthe visit, please check in at the EPA Region 6 reception area at 1445 Ross Avenue, Suite 700, Dallas, Texas.

FOR FURTHER INFORMATION CONTACT: Emad Shahin, Air Planning Section (6PDL), Environmental Protection Agency, Region 6, 1445 Ross Avenue, Suite 700, Dallas, Texas 75202-2733, telephone (214) 665-6717; fax number (214) 665-7263; e-mail address shahin.emad@epa.gov.3 

### SUPPLEMENTARY INFORMATION: Throughoutthis document wherever "we," "us," or "our" is used, we mean the EPA.



### OUTLINE: I. What Action is EPA Taking? II. What is the Background for this Action? III. What Comments did EPA Receive and how has EPA Responded to them? IV. Final Action V. Statutory and Executive Order Reviews



### I. What Action is EPA Taking? We are approving a portion ofthe submission from the State ofNew Mexico demonstrating that New Mexico has adequately addressed one ofthe required elements ofthe CAA section 11O(a)(2)(D)(i), the elementthat prohibits air pollutant emissions from sources within a state from contributing significantly to nonattainment ofthe relevant NAAQS in any other state. We have determined that emissions from sources in New Mexico do not significantly contribute to nonattainment ofthe 1997 8-hour ozone NAAQS or the 1997 PM 2.5 NAAQS in any other state. Because emissions from sources in New Mexico do not significantly contribute to nonattainment in any other state, section 11O(a)(2)(D)(i)(I) does not require any substantive changes to New Mexico's SIP. The remaining three elements ofsection 11O(a)(2)(D) are that a state's SIP contain adequate provisions to prevent: interference with maintenance ofthe NAAQS in any other state; interference with measures required to prevent significant deterioration ofair quality in any other

### 4 state; and interference with measures required to protect visibility in any other state. EPA will evaluate the New Mexico SIP and SIP submissions for compliance with these other requirements ofsection 11O(a)(2)(D) for the 1997 8-hour ozone and 1997 PM2.5 NAAQS in future rulemakings.



### II. What is the Background for this Action? On July 18, 1997, EPA promulgated new standards for 8-hour ozone and fine particulate matter (PM2.5). This action is being taken in response to the July 18, 1997 revision to the 8-hour ozone NAAQS and PM 2.5 NAAQS. This action does not address the requirements for the 2006 PM2.5NAAQS or the 2008 8-hour ozone NAAQS; those standards will be addressed in a later action. Section 110(a)(l) ofthe CAA requires states to submit SIPs to address a new or revised NAAQS within 3 years after promulgation ofsuch standards, or within such shorter period as EPA may prescribe. Section 11O(a)(2) lists the elements that such new SIPs must address, as applicable, including section 11O(a)(2)(D)(i) which pertains to interstate transport ofcertain emissions. On August 15,2006, EPA issued its "Guidance for State Implementation Plan (SIP) Submission to Meet Current Outstanding Obligations Under Section 11O(a)(2)(D)(i) for the 8- Hour Ozone and PM2.5 National AmbientAir Quality Standards" (2006 Guidance) for SIP submissions that states should use to address the requirements ofsection 110(a)(2)(D)(i). EPA developed this guidance to make recommendations to states for making submissions to meet the requirements ofsection 110(a)(2)(D) for the 1997 8-hour ozone NAAQS and 1997 PM2.5 NAAQS.5 On September 17,2007, EPA received a SIP submission from the State ofNew Mexico to address the requirements ofsection 110(a)(2)(D)(i) for both the 1997 8-hour ozone NAAQS and 1997 PM2.5NAAQS. The state based its submittal on EPA's 2006 Guidance. As explained in the 2006 Guidance, the "good neighbor" provisions in section 11O(a)(2)(D)(i) require each State to submit a SIP that contains adequate provisions to prohibitemissions from sources within that state from adversely affecting another state in the ways contemplated in the statute. Section 11O(a)(2)(D)(i) contains four distinctrequirements related to the impacts ofinterstate transport. In this rulemaking EPA is addressing only the requirementthatpertains to preventing sources in the state from emitting pollutants in amounts which will contribute significantly to nonattainment ofthe 1997 8-hour ozone NAAQS and the 1997 PM2.5NAAQS in any other state. In its submission, the State ofNew Mexico indicatedthat its current SIP is adequate to prevent such significant contribution to nonattainment in ariyother state, and thus no additional emissions controls are necessary at this time to alleviate interstate transport. On April 8, 2010, we published a direct final rule and aparallel proposal to approve the portion ofNew Mexico's SIP submission that addressed one elementofthe CAA section 11O(a)(2)(D)(i), which pertains to prohibiting air pollutant emissions from withinNew Mexico from contributing significantly to nonattainment ofthe 1997 8-hourozone and 1997 PM2.5 NAAQS in any other state (75 FR 17868). The directfinal rule and proposal stated that ifEPA received any relevant adverse comments during the public comment period ending on May 10, 2010, then EPA would withdraw the direct final rule and respond to such comments in a subsequent final action based upon the proposal. EPA received adverse comments during the commentperiod, and accordingly EPA withdrew the direct final rule on May 3, 2010 (75 FR 23167). The April 8,2010, proposal (75 FR 17894) provides the basis for today's final action.

### 6



### III. What Comments did EPA Receive and how has EPA Responded to them? EPA received three comment letters on the April 8,2010, direct final rule and proposal. The letters can be found on the internet in the electronic docket for this action. To access the letters, please go to 

### http://www.regulations.gov and search for Docket No. EPA-R06-0AR-2007- 0993, or contact the person listed in the 

### FOR FURTHERINFORMATION CONTACT paragraph above. The discussion below addresses those comments and our response.

A. Comments from WildEarth Guardians. 

### CommentNo.1

- The commenter argued that New Mexico and EPA did not appropriately

assess impacts to nonattainment in downwind states. According to the commenter, New Mexico failed to assess the significance ofdownwind impacts in accordance with EPA precedent and refers to the 1998 NOx SIP Call. 

### EPA Response

- EPA disagrees with the commenteron this point. Section 110(a)(2)(D) does not explicitly specify how states or EPA should evaluate the existence of, or extent of, interstate transport and whether interstate transport is ofsufficient magnitude to constitute "significant contribution to nonattainment" as a regulatory matter. The statutory language is ambiguous on its face and EPA mustreasonably interpretthat language when it applies it to factual situations before the Agency. EPA agrees that the NOx SIP Call is one rulemaking in which EPA evaluated the existence of, and extent of, interstate transport. In that action, EPA developed an approach that allowed the Agency to evaluate whetherthere was significantcontribution to ozone nonattainment across an entire region that was comprised ofmany states. That approach7 included regional scale modeling and othertechnical analyses that EPA deemed useful to evaluate the issue ofinterstate transport on that geographic scale and for the facts and circumstances at issue in that rulemaking. EPA does not agree, however, that the approach of the NOx SIP Call is the only way that states or EPA may evaluate the existence of, and extentof, interstate transport in all situations, and especially in situations where the state and EPA are evaluating the question on a state by state basis, and in situations where there is not evidence of widespread interstate transport. Indeed, EPA issued specific guidance with recommendations to states about how to address section 11O(a)(2)(D) in SIP submissions for the 1997 8-hour ozone NAAQS. EPA issued this guidance document, entitled "Guidance for State Implementation Plan (SIP) Submissions to Meet Current Outstanding Obligations Under Section 110(a)(2)(D)(i) for the 8- Hour Ozone and PM2.5 National AmbientAir Quality Standards" on August 15,2006. 1 This guidance documentpostdated the NOx SIP Call, and was developed by EPA specifically to address SIP submissions for the 1997 8-hour ozone NAAQS. Within the 2006 Guidance, EPA notes that it explicitly stated its view that 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.,,2 Moreover, within that guidance, EPA expressed its view that "the data and analytical tools available" at the time ofthe SIP submission "necessarily affect the contentofthe required submission.") To that end, EPA specifically recommended that states located within the

1 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-hourOzone and PM2.5 National Ambient Air Quality Standards (Aug. 15,2006) ("2006 Guidance"); p. 3. 2Id. at 3. 31d.8 geographic region covered by the Clean Air Interstate Rule (CAIR)4 comply with section 11O(a)(2)(D) for the 1997 8-hour ozone NAAQS by complying with CAIR itself. For states outside the CAIR rule region, however, EPA recommended that states develop their SIP submissions for section 11O(a)(2)(D)considering relevant information. EPA explicitly recommended that relevant information for section 11O(a)(2)(D) submissions addressing significant contributionto nonattainment "might include, but is not limited to, information concerning emissions in the State, meteorological conditions in the State, the distance to the nearestnonattainment area in another State, reliance on modeling conducted by EPA in determining that such State should not be included within the ambit ofthe CAIR, or such other information as the State considers probative on the issue ofsignificant contribution.t" In addition, EPA recommended that states might elect to evaluate significantcontributionto nonattainmentusing 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 interstate transport. The commenterdid not acknowledge or discuss EPA's actual guidance for section 110(a)(2)(D) SIP submissions for the 1997 8-hour ozone NAAQS, and thus it is unclear whether the commenterwas aware ofit. In any event, EPA believes that the New Mexico submission and EPA's evaluation ofit is consistent with EPA's guidance for the 1997 8-hour ozone NAAQS. For example, as discussed inthe direct final notice, the State ofNew Mexico and EPA considered information such as monitoring data in other states, geographical and meteorological information, and technical studies ofthe nature and sources ofnonattainmentproblems in

4 In this action the expression "CAIR" refers to the [mal 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); Revisions to Acid Rain Program; Revisions to NOx SIP Call; Final Rule" (70 FR 25162). 5 Id. at 5.9 various downwind states. These are among the types ofinformation that EPA recommended and that EPA considers relevant. Thus, EPA has concludedthat the State's submission, and EPA's evaluation ofthat submission, meet the requirements ofsection llO(a)(2)(D) and are consistent with applicable guidance. Finally, EPA notes that the considerations the Agency recommended to states in the 2006 Guidance are consistent with the concepts ofthe NOx SIP Call referenced by the commenter: (a) the overall nature ofthe ozone problem; 

### (b) the extentofdownwind nonattainmentproblems to which upwind state's emissions are linked; (c) the ambient impactofthe emissions from upwind States' sources on the downwind nonattainmentproblems; and (d) the availability of high cost-effective control measures for upwind emissions. The only distinction in the case of the New Mexico submission at issue here would be that because the available evidence indicates that there is so very little contribution ofemissions from New Mexico sources to nonattainment in other states, it is not necessary to advance to the final step and evaluate whether the cost of controls for those sources is above or below a certain cost ofcontrol as part ofdetermining whetherthe contribution constitutes "significantcontribution to nonattainment" forregulatory purposes, as was necessary in the NOx SIP Call and in CAIR.



### CommentNo.2

- The commenterbelieves that New Mexico and EPA did not appropriately assess impacts to nonattainment in downwind states in terms ofair quality. Specifically, the commenterobjectedto EPA's proposed approval because New Mexico assessed impacts in downwind states by considering only areas that had monitoring data as for evaluating significant contribution to nonattainment. In other words, the commenter is concerned that New Mexico did not assess impacts in areas that have no monitor. The commenter implied that this10 reliance on monitor data is inconsistent with both section 11O(a)(2)(D) and with EPA's guidance, by which the commenter evidently means the NOx SIP Call. In support ofthis assertion, the commenter 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 not to be limitedto 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)(I)(A)(I»" According to the commenter, this statement, and similar ones in the context ofthe final NOx SIP Call rulemaking, establishthat states and EPA cannotutilize monitoring data to evaluate the existence of, and extent of, interstate transport. Furthermore, the commenterinterprets the reference to "airquality" in these statements to support its contention, amplified in later comments, that EPA must evaluate significant contribution in areas in whichthere is no monitored nonattainment. EPA response - EPA disagrees with the commenter's arguments. First, the commenter misunderstands the point that EPA was making in the 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, independentofthe current formal "designation" ofsuch downwind states, it was not referring to air quality in the absence of monitor data. EPA's pointwas that it was inappropriate to wait for either initial designations of nonattainment for a new NAAQS under section 107(d)(l), or for a redesignationto nonattainment for an existing NAAQS under section 107(d)(3), before EPA could assess whether there is significantcontribution to nonattainmentofa NAAQS in another state.11 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 110(a)(l) requires states to make SIP submissions that address section 11O(a)(2)(D) and interstate transport "within 3 years or such shorterperiod as the Administratormay prescribe" ofEPA's promulgation ofa new or revised NAAQS. This schedule does not support a reading ofsection 11O(a)(2)(D) that is dependentupon formal designations having occurred first. This is a key reason why EPA determined that it was appropriate to evaluate interstate transportbased upon monitor data, not designation status, in the CAIRrulemaking. The commenter's misunderstanding ofEPA's statement concerning designation status evident! y caused the commenterto 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 NOx SIP Call and CAIR, EPA evaluated significant contribution to nonattainment as measured or predicted at monitors. For example, in the technical analysis for the NOx SIP Call, EPA specifically evaluatedthe 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 11O(a)(2)(D), and EPA's general approach to this threshold determination has not been disturbed by the courts." Finally, EPA disagrees with the commenter's argument that the assessment ofsignificant contribution to downwind nonattainment must include evaluation ofimpacts on non-monitored

6 Michigan v.

### u.s. EPA, 213 F.3d 663, 674-681 (D.C. Cir. 2000); North Carolina v. EPA, 531 F.3d 896, 913-916 (D.C. Cir. 2008) (upholding EPA approach to determining threshold despite remanding other aspects ofCAIR).12 areas. Neither section 110(a)(2)(D)(i)(I) provisions, nor the 2006 Guidance EPA issued for the 1997 8-hour ozone NAAQS, support the commenter's position, as neitherrefers to any explicit mandatory or recommended approach to assess air quality in non-monitored 

### areas," The same focus on monitor data as a means ofassessing interstate transport is found in the NOx SIP Call and in CAIR. An initial step in both the NOx SIP Call and CAIR was the identification ofareas with current monitored violations ofthe ozone and/or PM2.5 NAAQS. 8 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, the commenteris simply in error that EPA has not previously evaluatedthe presence and extent ofinterstate transport under section 110(a)(2)(D) by focusing on monitoring data. Indeed, such monitoring data was at the core ofboth ofthese efforts. In neither ofthese rulemakings did EPA evaluate significant contribution 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 that there is a violation ofthe 1997 8-hour ozone NAAQS or ofthe 1997 PM2.5 NAAQS in a particular area. EPA did not use photochemical modeling to determine ifan area is violating the 1997 8- hour ozone or 1997 PM2.5 NAAQS to designate the area as nonattainment without supporting monitoring data. EPA's regulations for these NAAQS, the monitoring requirements for these NAAQS, and EPA's guidance for designations for these NAAQS provide for such designations

7 2006 Guidance, p. 5. 8 "Based on this approach, we predicted that in the absence ofadditional control measures, 47 counties with air quality monitors [emphasis ours] would violate the 8-hourozone NAAQS in 2010

...." From the CAIR proposed rule ofJanuary 30, 2004 (69 FR 4566,4581). The NOx SIP call proposedrule action reads: " ... For current nonattainment areas, EPA used air quality data for the period 1993 through 1995 to determine which counties are violating the I-hour and/or 8-hour NAAQS. These are the most recent 3 years offully quality assured data which were available in time for this assessment." See, 62 FR 60336.

### 13 for violating areas to be based only on monitoring data. In addition, this is reasonable for these particularNAAQS because photochemical models, while based on the best science available, only provide a best estimate ofair quality. EPA's 2007 modeling guidance" recognizes that model results and projections will continue to have uncertainty. Therefore, even ifmodeling analyses indicated violation ofthe 1997 8-hour ozone NAAQS in other states, EPA would not make a determination that these areas should be designated nonattainment for these NAAQS without monitoring data in the areato support a determination ofnonattainment. In summary, in order for there to be significant contribution to nonattainment for either ofthese specific NAAQS, there mustbe a monitor with data showing a violation ofthat NAAQS. EPA has concluded that by considering data from monitored areas, its assessment ofwhether emissions from New Mexico contribute significantly to ozone nonattainment in downwind states is consistent with the 2006 Guidance, and with the approach used by both the CAIR rule and the NOx SIP Call, and EPA modeling guidance. CommentNo. 3 - 

### In support ofits comments that EPA should assess significant contribution to nonattainment in nonmonitored areas, the commenter argued that existing modeling performed by another organization "indicates that large areas ofneighboring states will be likely to violate the ozone NAAQS." According to the commenter, 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

9 EPA -454/B-07-002, April 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, available at http://www.epa.gov/scramOOI/guidance/guide/final-03-pm-rh-guidance.pdf.14 in WRAP Modeling and Relevantto Future Regional Ozone Planning'Y'" In short, the commenter 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 ofstates adjacentto New Mexico. EPA Response

- EPA disagrees withthis commenton several grounds. First, EPA does not agree that it is appropriate when satisfying the requirements ofSection 110(a)(2)(D) to evaluate significantcontribution to nonattainment for the 1997 8-hourozone NAAQS by modeling ambient levels in areas where there is no monitorto provide data to establish a violation ofthe NAAQS in question. Section 11O(a)(2)(D) does not require such an approach, EPA has not taken this approach in the NOx SIP Call or other rulemakings under section 11O(a)(2)(D), and EPA's prior analytical approach has not been disturbed by the courts. Second, the commenter'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 fourth maximum ozone reading for the year 2018, and as indicating that"

...air quality

... will exceed or violate [emphasis ours] the 1997 ozone NAAQS." By definition, a one year value ofthe fourth maximum above the NAAQS only constitutes an exceedance ofthe NAAQS; to constitute a violation ofthe 1997 8-hourozone NAAQS, the average ofthe fourth high for three consecutive years at the same monitormust exceed the standard. Thus, even ifthe WRAP presentation submitted by the commenterwere technically sound, the conclusion drawn from it by the

10 The presentation is available for review as Document ID # EPA-R06-0AR-2007-0993-0008.9 at Regulations.gov, Docket ID # EPA-R06-0AR-2007-0993.

### 15 commenter is inaccurate and does not support its claim ofprojected violations ofthe NAAQS in large areas (monitored or unmonitored) ofNew Mexico's neighboring states. Even ifEPA believed that it was appropriate to use modeling to establish violations of the 1997 8-hour ozone NAAQS, EPA has reviewed the WRAP presentation submitted by the commenter, and believes that there 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 Four Comers Air Quality Task Force (FCAQTF)ll has demonstrated that excessive vertical transport in the CMAQ and CAMx models overhighterrain was responsible for overestimated ground level ozone concentrations due to downward transport ofstratospheric

ozone. 12 Environ has developed revised vertical velocity algorithms in a new version ofCAMx that eliminated the excessive downward transport ofozone from the top layers ofthe model. This revised version ofthe model is now being used in a number ofapplications throughout high terrain areas in the West. In conclusion, EPA believes that this key inadequacy ofthe WRAP model, noted above, makes it inappropriate support for the commenter's concerns about large

areas ofother states violating the 1997 8-hourozone NAAQS projected for 2018 in areas without monitors. CommentNo. 4 - As additional support for its assertion that EPA should require modeling to assess ambient levels in unmonitored portions ofother states, the commenterrelied

on an additional study entitled the "2009 Uinta Basin Air Quality Study" (UBAQS). The commenter argued that the UBAQS further supports its concern that New Mexico and EPA,

II This document is available for review at the regulations.gov web site under Docket ID No. EPA-R06-0AR-2007- 0993 12 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," pp. ES-3, ES-4, 3-4, 3-12, 3-30, 5-1. Prepared for the New Mexico Environment Department, Air Quality Bureau, Santa Fe, NM, by ENVIRON International Corporation, Novato, CA.

### 16 having limited the evaluation ofdownwind impacts only to areas with monitors, failed to assess

ozone nonattainment in non-monitored areas. According to the commenter, UBAQS modeling':' results show that: (a) the Wasatch Front region is currently exceeding and will exceed in 2012 the 1997 8-hour ozone NAAQS; and (b) based on 2005 meteorological data, portions ofthe four counties in the southwestern corner ofUtah are also currently in nonattainment and will be in nonattainment in 2012.!4 EPA Response -As noted above, EPA does not agree that it is appropriate toassess significant contribution to nonattainment for the 1997 8-hour ozone NAAQS in the way advocated by the commenter. In particular, EPA does not agree that it is necessary to evaluate significant contribution to areas where only the model predicts nonattainment where there are no monitors. Even ifEPA felt it was appropriate to use model results to determine areas that are not attaining the standard, EPA does not agree that the modeled nonattainment ofthe 1997 8-hour ozone NAAQS (current and projected) in the Wasatch Front Range area in the UBAQS supports the commenter's concerns about the need to evaluate the possibility ofsignificant contribution from New Mexico to nonattainment in these areas. Based on what the commenterpresented, EPA sees several problems with the commenter's interpretation ofthe UBAQS analysis results for counties in Utah's southwestern corner: "based on 2005 meteorological data, portions of Washington, Iron, Kane, and Garfield Counties are also in nonattainment and will be in

13 In this action the expression "UBAQS" refers to the "FINAL REPORT UBAQS TECHNICAL REPORT", June 30,2009. The presentation is available for review as Document ID # EPA-R06-0AR-2007-0993-0008.9 at regulations.gov, Docket ID # EPA-R06-0AR-2007-0993.

14 UBAQS. The southwestern area referred to by the commenter includes portions ofWashington, Iron, Kane, and Garfield Counties.17 nonattainment in 2012.,,15 First, the commenter's interpretation ofthe predicted ozone concentrations shown in Figures 4-3a and 4-3b (pages 4 and 5 ofthe comment letter) is inaccurate. A close review ofthe legend in these figures indicates that the highest ozone concentrations predicted by the model for portions ofthe counties noted above are somewhere between 81.00 and 85.99 ppb, but the exact modeled value is not specified and there are only three grid cells with this value range estimated. Ifthe actual model prediction is less than or equal to 84.94 ppb then the area is attaining the 1997 8-hourozone NAAQS, ifit is predicted as greater than 84.94 ppb thenthe modeling is indicating that it is not attaining those NAAQS. Thus, the current and predicted design values for the three grid cells in southwestern Utah area identified in Figures 4-3a and 4-3b could both be in attainment, or both in nonattainment, or one ofthem in attainment and the other in nonattainment, for the 1997 8-hour ozone NAAQS. EPA does not believe that this evidence adequately establishes that one or both areas definitely violate the NAAQS, even ifthe information were taken at face value. Second, even ifthe design values predicted for these unmonitored areas were at the top of the 81.00-85.99 ppb range, theirreliability would remain questionable. The UBAQS itself identifies and illustrates major shortcomings ofits modeling analysis, only to neglect assessing the impact ofthese shortcomings on the modeling results. 16 The study deviates in at least two significant ways from EPA's 2007 guidance on SIP modeling.!" One deviation is the UBAQS modeling reliance on fewer than the five years ofdatarecommendedby EPA to generate a

IS WG's April 16, 2010 comment letter, pp. 3. The letter is available for review at the regulations.gov web site Docket 10No. EPA-R06-0AR-2007-0993. Page three ofthe commenter's letter 16 See UBAQS, pp. 4-27 to 4-29. 17 EPA, Guidance on the Use ofModels and other Analyses 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 (2007), available at http://www.epa.gov/scramOOl/guidance/guide/final-03-pm-rhguidance. pdf.18 8-hour ozone current design value (DVC). UBAQS relaxed this requirement so that sites with as little as I year ofdata were included as DVCs in the analysis. The other deviation is in the computation ofthe relative responsive factor (RRF), which directly affects the modeling's future design value (DVF).18 Due to unavailability ofdata satisfying EPA's recommendation 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. 19Also, looking at Figures 3-19a-j ofthe UBAQS report, which cover ozone modeling performance through September of2005, shows the modeling to have an over prediction bias for ozone. So, EPA concludes that the modeling analysis results provided by the commenter are unreliable for projecting nonattainment status even ifEPA believed it was appropriate to use modeling for this purpose for the 1997 8-hr ozone NAAQS. Finally, even ifit were appropriate to consider modeled violations and the modeling were reliable for this purpose, the commenterhas not raised any convincing evidence that emissions from New Mexico sources are impacting southwestern Utah during the predicted high ozone events. Specifically, no assessment or source apportionment was performedthat indicated

sources in New Mexico contributed to the three grid cells with modeled high values that may be modeled nonattainmentvalues in Utah. In fact, the predominant wind direction would not carry emissions from New Mexico into southwestern Utah. Furthermore, in evaluating the Figures provided (Fig 4-3ato 4-4b) and other information in the modeling report, the modeling also does not indicate that emissions from New Mexico are impacting the higher modeled ozone values in the southwestern Utah area.

18 Id., DVe xRRF =DVF. 19 See UBAQS, p. 4-2819 In summary, EPA does not agree that it is appropriate for purposes ofsection 110(a)(2)(D) to use modeled nonattainment as a basis for evaluation, for these two NAAQS (1997 8-hour ozoneNAAQS and PM 2.5 NAAQS) especially in light ofthe concerns with the modeling discussed above. Even ifEPA were to use modeling for this purpose, the UBAQS modeling analyses does not clearly predict violations ofthe 1997 8-hour ozone NAAQS in western Colorado and eastern Utah. In particular, the UBAQS modeling does not clearly establish violations ofthe NAAQS in southwestern Utah because ofthe way the results were reported. Significantly, the model does project violations in the Salt Lake City area (in 2006 and 2012 model years), but monitors in the area do not substantiate these modeledpredictions. Based on monitoring data for 2007-2009, the Salt Lake City area does not have a monitored design value within 6 ppb ofthe level ofthe 1997 8-hour ozone NAAQS. In addition, EPA does not considerthe UBAQS modeling reliable because the modeling deviates from EPA guidance and appears to have an over-prediction bias. Finally, the commenterdid not provide evidence that emissions from New Mexico in fact contributed significantly to the modeled exceedances or violations projected in this modeling. CommentNo. 5 - 

### In support ofits arguments that EPA should not assess significant contribution to nonattainmentthrough evaluation ofimpacts at monitors instead ofmodeling impacts where there is no such monitor, the commentercited a past statementby EPA to the effectthat the ozone monitoring network in the western United States needs to be expanded. The quoted statements includedEPA's observation that: "[v]irtually all States east ofthe Mississippi Riverhave at least two to four non-urban 03 monitors, while many large mid-western and western States have one or no non-urban monitors." 74 FR 34,525 (July 16,2009). From this statement, the commenter argues that it is not appropriate for EPA to limit evaluation of20 significant contribution to nonattainrnent ofthe ozone NAAQS in other states to reliance on monitoring data instead ofmodeled ambient levels. EPA Response

- EPA does not disagree that there are relatively few ozone monitors in the western states, and that relatively few ofthese ozone monitors are currently located in nonurban areas ofwestern states. However, the commenter failed to note that the quoted statement from EPA concerning the adequacy ofwestern monitors came from the Agency's July 16,2009, proposed rulemaking entitled "Ambient Ozone Monitoring Regulations: Revisions to Network Design Requirements." This statement was thus taken out ofcontext, because EPA was in that proposal referring to changes in state monitoring networks that it anticipates will be necessary in orderto implementnot the 1997 8-hour ozone NAAQS, the subject ofthis rulemaking, butrather the next iteration ofthe ozone NAAQS. Because the new ozone standard is likely to be significantly more stringentthan the 1997 8-hour ozone NAAQS, it is anticipated there will be a need to evaluate ambient levels in previously unrnonitored areas ofthe western United States. The fact that additional monitors may be necessary in the future for a newer ozone NAAQS does not mean that the existing ozone monitoring networks are insufficient for the 1997 8-hour ozone NAAQS, as the commenter implies. Indeed, states submit annual monitor networkreports to EPA and EPA evaluates these to insure that the deployment ofmonitors in the state meets the applicable regulatory requirements and guidance recommendations. For example, New Mexico itselfsubmitsjust such a report on an annual basis, and EPA reviews it for adequacy.i" All states submitcomparable reports. Absent a specific concern that another state's current monitor network is inadequate to evaluate ambient levels ofthe 19978-

20 See the New Mexico Annual Monitoring Network Plan dated July 14,2009. The plan is available for review at the regulations.gov web site under Docket ID No. # EPA-R06-0AR-2007-0993.21 hour ozone NAAQS, EPA has no reason to believe that the evaluation ofpossible significant contribution from New Mexico sources in reliance on those monitors is incorrect. 

### CommentNo.6

- The commenter objectedto EPA's proposed approval ofthe New Mexico's SIP submissionbecause neither New Mexico nor EPA performed a specific modeling analysis to assure that emissions from New Mexico sources do not significantly contribute to nonattainment ofthe 1997 8-hour ozone NAAQS in downwind States. 

### EPA Response

- First, this comment is incorrect. EPA and New Mexico did provide modeling as part ofthe evaluation ofwhether emissions from sources in New Mexico impact monitors with violating data in other states. The modeling is discussed in the proposed federal register and technical support document for this action and is one ofthe primary considerations in EPA's approval. The modeling that the commenter claims is necessary but absent, is modeling to assess impacts in areas with no monitors. As explained above, EPA believes that the assessment ofsignificant contribution to nonattainment under section 110(a)(2)(D) for these NAAQS should be based upon impacts at monitors. Second, EPA disagrees with the commenter's beliefthat only modeling can establish whether or not there is significant contribution from one state to another. As noted above, EPA does not believe that section 110(a)(2)(D) requires modeling. While modeling can be useful, EPA believes that other forms ofanalysis can be sufficientto evaluate whether or not there is significant contribution to nonattainment. For this reason, EPA's 2006 Guidance recommended other forms ofinformation that states might wish to evaluate as a qualitative approach as partof their section 110(a)(2)(D) submissions for the 1997 8-hourozone NAAQS. EPA has concluded that the qualitative approach used by New Mexico in addition to modeling to assess the existence22 of, and extent of, any significantcontribution to downwind ozone nonattainment is consistent with EPA's 2006 Guidance. CommentNo. 7 - In further support ofits argument that EPA must use modeling to evaluate whether there is significant contribution to nonattainmentunder section 11O(a)(2)(D), the commenter noted that EPA itselfasks other agencies to perform such modeling in other contexts. As examples, the commentercited four examples in which EPA commented on actions by other agencies in which EPA recommended the use ofmodeling analysis to assess ozone impacts priorto authorizing oil and gas developmentprojects. As supporting material, the comment includes quotations from and references to EPA letters to Federal Agencies on assessing impacts ofoil and gas development 

### projecta." The commenterquestioned 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 New Mexico's emissions and to insure compliance with Section 110(a)(2)(D)(i)(I). The commenterreasoned that the emissions that would result from the actions at issue in the other agency decisions, such as selected oil and gas drilling projects, would be ofless magnitude and importance than the statewide emissions at issue in an evaluation under section 11O(a)(2)(D). EPA Response

- As explained above, this comment is misplaced because EPA and New Mexico did employ modeling as part ofthe evaluation. Further, EPA disagrees with the commenter's fundamental argumentthat modeling is mandatory in all instances in orderto evaluate significant contribution to nonattainment, whetherby section 11O(a)(2)(D), by EPA guidance, or by pastEPA precedent. EPA's applicable guidance made recommendations as to

21 WG's April 16, 2010 comment letter, pp. 8-9. 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-R06-0AR-2007-0993-0008.3 through 0993-0008.6.23 different approaches that could lead to demonstration ofthe satisfaction ofthe interstate transport requirements for significant contribution to nonattainment in other states. EPA explicitly recommended thatrelevant information for section 110(a)(2)(D) submissions addressing significant contributionto nonattainment "might include, but is not limited to, information concerning emissions in the State, meteorological conditions in the State, the distance to the nearest nonattainment area in another State, reliance on modeling conductedby EPA in determining that such State should not be included within the ambit ofthe CAIR, or such other information as the State considers probative on the issue ofsignificantcontribution." Even EPA's own CAIR analysis relied on a combination ofqualitative and quantitative analyses. EPA's CAIR analysis excluded certain western states on the basis ofa qualitative assessment of topography, geography, and 

### meteorology.f Furthermore, EPA believes that the commenter's references to EPA statements commenting on the actions ofother agencies are inapposite. As the commenter is aware, those comments were made in the context ofthe evaluation ofthe impacts ofvarious federal actions pursuantto National Environmental Policy Act, not the Clean Air Act. As explained above, in the context ofsection IIO(a)(2)(D), EPA does not agree that only modeling is always required to make that differenttype ofevaluation, and EPA itselfhas relied on other more qualitative evidence when it deemed that evidence sufficientto reach a reasoned determination. 

### CommentNo.8

- In further support ofits argument that EPA should require a specific type ofmodeling to evaluate significant contribution to nonattainment, the commenterreferred to EPA regulations governing nonattainment SIPs. The commenter noted 40 CFR 51.112(a)(l), which states that: "[t]he adequacy ofa control strategy shall be demonstrated by means of

22 See 69 FR 4581, January 30, 2004.24 applicable air quality models, databases, and other requirements specified in appendix W of [Part 51] (Guideline on Air Quality Models)." The commenter argues that this regulation appears to supportthe commenter's position that modeling is required to satisfy the significant contribution element ofllO(a)(2)(D). EPA Response - EPA disagrees with this comment. The cited language implies that the 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 determination that emissions from sources in New Mexico do not contribute significantly to nonattainment for the 1997 8-hour ozone NAAQS in any other state eliminates the need for a control strategy aimed at satisfying the section llO(a)(2)(D) requirements. Moreover, EPA interprets the language at 40 CFR 51.112(a): "[e]achplan must demonstrate that the measures, rules, 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 underpart 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). This modeling may also be appropriate under certain circumstances for maintenance SIPs under section llO(a)(1). Thus, the commenter's cited regulation is not relevantto EPA's technical demonstration assessing whetheremissions from New Mexico contribute significantly to nonattainment in any other states under section llO(a)(2)(D)(i). CommentNo. 9 - The commenterexpressed concern with EPA statements in the proposed approval about the current factual attainment ofthe Denver MetrolNorth FrontRange

area ofColorado. The commenternoted that nine counties in the Denver area are currently25 formally designated "nonattainment" for the 1997 8-hour ozone NAAQS. The cornmenter took issue with EPA's description ofthe nature ofthe nonattainment problem in this area as resulting from an unusually bad ozone seasonthat "temporarily" resulted in violations ofthe NAAQS. The cornmenter argued that data from the 2001- 2003 period and the 2005-2007 period showed consistent violations ofthe 1997 8-hour ozone NAAQS in the Denver area, and that these violations are the reason for the current nonattainment designation. EPA Response

- EPA disagrees that formal designation status ofan area is the most important consideration in evaluating the existence of, and extent of, the impacts ofinterstate transport from one state to another. In past actions under section 11O(a)(2)(D), EPA has interpretedthat provision to turn upon the actual monitored ambient levels in a downwind area, regardless ofthe formal designation status ofthe area. For example, EPA developed the CAIR rule based upon evaluation ofmonitor data showing violations ofthe 1997 PM2.5 NAAQS in certain areas, in advance ofcompleting the designation process for those NAAQS under section 107(d). 23 EPA agrees that the designation status ofan area is a relevant consideration, but the actual monitored ambient levels are an appropriate measure, especially when there is evidence that the monitored levels are differentthan reflectedby the designation for the area. EPA itself has also looked to future attainment status as a means ofevaluating the presence of, and extents of, interstate transport. This analysis depends not upon the anticipated formal designation status ofthe area, but rather upon the anticipated monitored level ofthe area/"

23 See: Final CAIR rule, 70 FR 25,162,25,263 - 25,269. 24 EPA notes that the commenter itselfalso made the argumentthat nonattainment for purposes ofsection 110(aX2XD) should be viewed "in terms ofair quality, and not in terms ofarea designations" on page 2 ofits own comment letter.26 EPA believes that the commenter is placing undue importance upon the EPA's characterization ofthe data from Denver area monitors as ''temporarily'' in nonattainment based on the "bad" ozone season of2007. EPA agrees that this area has historically had relatively high ambient levels. However, as explained in the proposal, these levels have improved, and more importantly, have improved during the periodthat is most relevant and mostrecent. As noted in the proposal, recent monitoring data from the Denver area for the 2007 - 2009 period indicates that the area is belowthe level ofthe NAAQS. For this trend to change, EPA anticipates that the Denver area would have to have dramatically higher ozone levels in 2010 than the area has experienced for many years. EPA believes that it is more reasonable to conclude that the monitored attainment ofthis area at the time ofthe analysis done by New Mexico will continue. Therefore there could not be significantcontribution from sources inNew Mexico to nonattainment in Denver. EPA believes that the downward trend in monitored nonattainment in the Denver area supports this conclusion. At the time the modeling was performedto supportthe state's section 110(a)(2)(D) submission, Denver was monitoring attainment (the 2004-2006 8-Hour Ozone Design Value (DV) was 81 ppbi5• In 2007, the Denver area experienced a particularly bad ozone season, and inclusion ofthe data from this year did temporarily affectthe monitored values in this area. However, the most recent data for this area, preliminary data for 2007-2009 DV (awaiting final data validation), is 82 ppb even with inclusion ofthe very high ozone values from 2007. Thus, the area's most recentDV based upon preliminary data is several ppb below the 1997 8-hour ozone NAAQS, and the area is therefore currently monitoring attainment.

2S Data from EPA's Air Quality System which is EPA's repository ofambient air quality data . (http://www.epa.gov/ttn/airs/airsaqsl)27 The downward trend in ozone concentrations is in part the result ofa sustained effort to attain the NAAQS in the Denver area. The Denver area has seen a drop in ozone levels in the last 10 years attributable in part to federal measures that have reduced mobile source emissions. In addition, Colorado adopted an Ozone Action Plan in December 2008 that included additional reductions in emissions ofozone precursors (NUx and VOCs), that will further aid the area in maintaining attainment. Given these facts, EPA concludes that the monitored attainment ofthe 1997 8-hour ozone NAAQS in the Denver area is likely to continue. CommentNo. 10

- The commenter also disputed the EPA statement in the proposal that it is "unlikely that Denver will be in nonattainment at the end ofthe 2010 ozone season," and questioned why EPA did not cite or include any actual model data to supportthis assertion. The commenter specifically took issue with EPA's reference to the "2010 ozone season" in the proposal because section 11O(a)(2)(D) would prohibit significant contribution to nonattainment at all times, not simply during the "2010 ozone season." EPA Response

- As discussed above, EPA believes the monitoring data adequately demonstrates that the Denver area is attaining the standard and is likely to continue to do so. The commenter is correctthat EPA did not cite modeling that showed that Denverwould be in attainment in 2010 in the proposal. We are aware, however, ofthe photochemical modeling for Denver completed as part ofthe "Ozone Action Plan" adopted by Colorado in December2008. 26 This plan included the benefits offederal measures and fleet turnover and additional local NOx and VOC reductions. The plan also included photochemical modeling that indicated all monitors in the area would be in attainment ofthe 1997 8-hour ozone NAAQS in 2010. The modeling

26 "Denver Metro Area & North Front Range Ozone Action Plan Including Revisions to the State Implementation Plan", Approved by Colorado Air Quality Control Commission, December 12,2008.28 results supplementthe monitoring results discussed previously indicating the area is in attainment and will be in attainment in 2010. Further, EPA believes thatthe commenter is mistakenly assuming that EPA's reference to the "2010 ozone season" implied that section IIO(a)(2)(D) would not require the elimination ofemissions from sources in an upwind state that significantly contributed to violations ofa NAAQS at any time ofthe year. In the case ofthe 1997 8-hour ozone NAAQS, however, it is a fact that there is an "ozone season" in many places across the county. Higher ozone concentration levels typically occur during the warmer, sunnierportions ofthe year, especially the summer. Like most areas, Denverhas an ozone season. Therefore, it is not unreasonable for EPA to evaluate the likely impacts ofdata from monitors in this area during the "ozone season." EPA also disagrees that an evaluation focused on impacts on 2010 levels is not adequate for purposes ofsection 110(a)(2)(D). As further discussed elsewhere in this notice, EPA's 2006 Guidance to states for section IIO(a)(2)(D) SIP submissions recommended that states might elect to evaluate the existence of, and extent of, significant contribution to nonattainment in other states by evaluating impacts as ofan appropriate year (such as 2010) and in light ofthe cost of control to mitigate emissions thatresulted in interstate transport. EPA itselfin the context ofthe CAIRrule evaluated whetherthere would be such impacts in 2010. This yearwas a reasonable choice, because it correlated with the presumptive attainment dates for states with nonattainment areas. For example, in the case ofthe 1997 PM2.5 NAAQS, the applicable attainment date is as expeditiously as practicable, but not laterthan five years from the effective date ofthe designation, i.e., by 2010. Because 2010 is a reasonable date for this analysis, given the purpose ofsection 110(a)(2)(D), and is consistent with EPA's recommendations in the 2006 Guidance, EPA concludes that the selection ofthis date for the analysis supporting the New Mexico29 submission was appropriate. The commenter did not suggest another date that would be more appropriate nor did they explain the basis for requiring a different year for this analysis. CommentNo. 11- The commenter also asserted that EPA was wrong in stating that the Denver area had not experienced a 4th highest 8-hour ozone reading of92 ppb in the last 15 years. The commenter claimed that the Denver metro area experienced a 4th highest max of95 ppb at the Roxborough Park monitor in Douglas County in 2005 and of95 ppb at the Applewood monitor in Jefferson County in 1998 and in 2003. EPA Response

- In response to this comment, EPA rechecked the data in the EPA's Air Quality System (AQS) and believes the commenter was in error that a fourth highest maximum of95 ppb occurred at the Roxborough Park (also know as the Chatfield monitor) monitor in 2005. EPA's AQS indicates a value of84 ppb in 2005. However, EPA's AQS does indicate that a 95 ppb 4th high occurred in 2003 at the Roxborough Park monitor and this may be the date that the commenter intended. 

### In any event, upon closer examination, EPA concludes that the commenter is correctthat values above 92 ppb have occurred in the Denver area in the last 15 years. EPA also notes that the current DVs (2007-2009) for these two monitors (Roxborough Park and Applewood) are 77 ppb and 76 ppb, which is well below the 1997 8-hour ozone NAAQS. Furthermore, these monitors would have to have fourth high daily maximum 8-hour monitored values of 104 and 111 ppb respectively in 2010 to have a 2008-2010 DV violating the 1997 8-hour ozone NAAQS. The fourth high daily maximum value monitoredthe last 15 years in the Denver area was 95 ppbwhich is significantly lower than the 104 or 111 ppb values that would have to be monitored for either ofthese two monitors to be violating the 1997 8-hour

ozone NAAQS.30 Therefore, EPA believes that the commenter's correction that there have been higher values (maximum of95 ppb in the last 15 years) at monitors in the Denver area does not fundamentally affect EPA's evaluation in this case. The higher values were not at the monitor that was the basis for the Denver area design value in the last several years. The monitorthat has been the basis for the Denver area DV has been the Rocky Flats North monitor. Even though the commenter is correctthat the area has monitored higher values at certain monitors in the past, these monitors are not the monitors that have in recent years determined whetherthe area will continue to monitor attainment because they have not recorded the highest design value in the area. The Rocky Flats North monitorhas the highest 2007-2009 Denver area DV of82 ppb and is based upon fourth high values of90 ppb in 2007, 79 ppb in 2008, and 79 ppb in 2009. This monitor would have to have a fourth high daily maximum of97 ppb in 2010 to result in a violation ofthe 1997 8-hour ozone NAAQS. Therefore, it does not change EPA's conclusion that the Denver area continues to monitor attainment and therefore emissions from sources in New Mexico cannot be contributing significantly to violations ofthe 1997 8-hour ozone NAAQS in this area. CommentNo. J 2 - The commenteralso pointedto modeling data used by New Mexico that appears to contradict the conclusion that emissions from New Mexico do not contribute significantly to violations ofthe 1997 8-hour ozone NAAQS in Denver. The commenter argued that data available inNew Mexico's own technical support documentthat was part ofEPA's record (DocketNo. EPA-R06-0AR-2007-0993) establish that emissions from New Mexico

sources "often contributes greaterthan 2 parts per billion in ozone on days when exceedances of the 1997 ozone NAAQS are recorded in Denver" and can contribute "more than 5% to Denver's total ozone concentrations." Finally, the commenterargued that New Mexico wrongly assumed31 that this amount ofcontribution was not relevant "underthe assumption that the region was not in nonattainment" when the area is currently designated nonattainment. EPA Response- EPA disagrees with the cornmenter's conclusions drawn from the modeling. The modeling was conducted using an emissions inventory from 2002. Because emissions in the year 2010 are expected to be lower, EPA considers this modeling to be a conservative estimate ofozone levels in the future and ofthe impact ofNew Mexico's emissions on other states. EPA believes that the modeling shows higher impacts than are actually occurring. The modeling utilized existing CENRAP modeling databases available at the.time and the source apportionment evaluation was conducted using the 2002 emission inventory databases. Because the available databases were for 2002 and not 2010, EPA considers the results ofthe modeling conservative because significant emissionreductions are expected to

occur throughout the modeled area between 2002 and 2010 (as a result ofboth federal and state measures, including fleet turnover impacts) that would result in lower ambient ozone levels and fewer exceedances ofthe 1997 8-hourozone NAAQS throughoutthe modeling domain. Specifically, there are three elements in this analysis that EPA concludes leadto overestimation ofthe impacts ofNew Mexico sources and therefore make this modeling less reliable to determine that sources in New Mexico contribute significantly to violations ofthe 1997 8-hour NAAQS in Colorado (or any other state). These three elements that result from using a 2002 and not a 2010 emission inventory are: (a) additional emissions reductions in other states as a result ofozone nonattainment SIPs have been implementedthat were not reflected in the 2002 emission 

### inventoryr'(b) additional emissions reductions as a result offederal measures

27 Additional emission reductions have occurred as a result ofI-hour ozone and 8-hour ozone nonattainment area SIPs for Denver and other areas in the modeling domain (Dallas, Houston, etc.). The most recent SIP submitted indicated that all ofthe Denver area monitors would be in attainment in 2010 with the 1997 8-hourozone32 (including On-road, Non-road, and the impacts offleet turnover) throughout the modeling domain since 2002; and (c) additional reductions from large stationary NOx sources and from mobile sources as a result offederal measures that have occurred in New Mexico since 2002. As a result ofthese differences in the emission inventory between 2002 and 2010, New Mexico's Technical Support Document describing and evaluating the modeling indicated that the impacts for New Mexico's emissions were considered conservative estimates and were expected to overstate the State's contribution to areas in other states. EPA believes that these conservative assumptions make the modeling reliable for purposes ofdetermining that there is not a significant contribution from sources in New Mexico to the other states, but less reliable for purposes ofdetermining that there is such significant contribution. EPA believes that the modeling relied upon by the State is conservative because ofthe three emission elements discussed above and that this is further supported by studies referred to by the commenter. Other studies support the conclusion that the Denver area will be monitoring attainment in 2010 for the 1997 8-hourozone NAAQS, and therefore emissions from sources in New Mexico would not be contributing significantly to nonattainment in this area. Specifically, the WRAP model emission inventories for 2002 and 2018 showed decreases nationally in ozone precursors (NOx and 

## voc.r' The UBAQS modeling report included emission inventory assessments between 2006 and 2012 that also showed decreases in New Mexico's NOx emissions for the part ofNew Mexico that was in the 12 km modeling grid. 29 Finally, the fact that Denver is monitoring

NAAQS. The Denver SIP also-included an analysis ofemission inventories in the Denver area that showed a net decrease in NOx and VOC emissions between 2006 and 20 I0 (Ibid DOAP) despite the inclusion ofgrowth in Oil and Gas emissions in the Denver area. (DOAP) 28 WRAP EDMS,. http://vista.cira.colostate.edu/TSS/EDMS.aspx 29 "UINTA BASIN AIR QUALITY STUDY (UBAQS)", prepared by Environ for the Independent Petroleum Association ofMountain States (IPAMS), June 30, 2009. Tables 2-18 and 2-20. The UBAQS 12 kIn grid included33 attainment at this time is further indication that the 2002 modeling was conservative because it predicted exceedances in Denver, while the 2010 monitoring data is showing attainment. Because the modeling was conservative and overstates the extent ofcontribution from

sources in New Mexico to the Denver area, it is inappropriate to use the modeling as a definitive determination ofNew Mexico's impacts on downwind areas. The modeling was designed to be conservative and as such only provides a clear indication ofnon impact on downwind nonattainment areas. Therefore, EPA disagrees that the modeling supports the conclusion of significant contribution from New Mexico sources to the Denvernonattainment area as the commenter indicated. The commenter is correctthatthe CENRAP based modeling with a 2002 emission inventory showed impacts that were above 2 ppb and contribution levels that were above 5 

### %, but due to the conservative nature ofthe 2002 assessment, EPA does not conclude that it indicates that sources in New Mexico have a significant contribution to nonattainment in Denver.EPA also believes that NOx emissions in upwind states are the most relevant consideration for interstate transport ofozone. In the final CAIR rule, EPA concluded thatNOx emissions were the primary pollutantto reduce in orderto yield reductions in interstate transport ofemissions that affect levels ofozone in the context ofthe 1997 8-hourozone NAAQS. 30 Recentphotochemical modeling in the New Mexico and Colorado region further supportthis conclusion, and therefore we have thus focused on NOx emissions in the context ofozone in this action as well.

parts ofnorthwestem New Mexico (including parts ofthe San Juan basin) and the emission inventory data indicated that emissions ofNOx from this area were going to decrease from 115,942 tpy in 2006 to 95,867 tpy in 2012.

30 See: Final CAIRrule, 70 FR 25162, 25174 ("As discussed in section III below, for 8-hour ozone, we reiterate the fmding ofthe NOX SIP Call that NOX emissions, and not VOC emissions, are ofprimary importance for interstate transport purposes.")

### 34 As reflected in the New Mexico submission and the UBAQS modeling documentation, New Mexico has decreased emissions ofNOx from several sources which would lessen New Mexico's impact on ozone in areas outside ofNew Mexico. Therefore, the reductions in NOx emissions inNew Mexico would decrease the impacts from New Mexico on Denver's ambient ozone levels when transport conditions would occur that New Mexico's emissions could impact the Denver area. A review ofthe UBAQS report indicates New Mexico's NOx reductions are mostly from elevatedpoint source reductions (Le. from tall stationary source stacks). Elevated emissions would have the greatestchance to transport downwind, so these reductions are likely among the most effective at reducing long range transport impacts on ozone levels regionally. In any event, based on preliminary 2007-2009 data, Denver is attaining the 1997 8-hour ozone NAAQS. Therefore, New Mexico's emissions cannotbe considered as contributing significantly to nonattainment ofthose NAAQS in the Denver area In summary, the Denver area is monitoring attainment ofthe 1997 8-hour ozone NAAQS. The modeling submitted by the State to support its submission indicating impacts from

sources in New Mexico on the Denver area is conservative, and probably overestimates both the ozone levels in Denver and any impacts from New Mexico's emissions. There have been significant emission reductions in the modeled area, supporting the conclusion that the modeling based on 2002 represents a conservative description ofozone levels and New Mexico's impact on the Denver area and therefore should not be relied upon solely to draw a conclusion about the impactofemissions from New Mexico in the Denver area. Considering the modeling in conjunction with the expected emission reductions and the actual monitoring data in this area, EPA concludes that emissions from New Mexico are not contributing to nonattainment ofthe 1997 8-hour ozone NAAQS in the Denver area.

### 35 CommentNo. J 3 - The commenter argued that New Mexico and EPA inappropriately relied on analyses conducted in connection with CAIR tojustify its conclusionthat emissions from sources in New Mexico do not contribute significantly to nonattainment in downwind states with regards to the 1997 PM 2.5 NAAQS. According to the commenter, neither ofthe modeling analyses EPA used during the development ofthe CAIR rule supports the conclusion. The commenter acknowledged that the REMSAD modeling that EPA used initially for CAIR in 2004 assessed emissions from New Mexico, but claimed that EPA eventually "rejected" this modeling and replaced it with analysis using the CMAQ model as a more "accurate" means ofassessing PM 2.5 impacts among states. The commenter did note that EPA explained in the final CAIR rule that it believedthe REMSAD model "treats the key physical and chemical processes associated with secondary aerosol formation and transport," but pointedto EPA's statementthat the REMSAD model "does not have all the scientific refinements ofCMAQ" and also to EPA's use ofthe CMAQ modeling for the final CAIR rule instead ofthe REMSAD modeling. The commenterthus implied that the REMSAD modeling could have no relevance to whether emissions from New Mexico sources contribute significantly to nonattainment in other states for purposes ofthe 1997 PM2.5 NAAQS. Similarly, the commenter argued that the CMAQ modeling could not supportthe conclusion that New Mexico sources are not contributing significantly to violations ofthe NAAQS in other states. The commenter claimed that although New Mexico was included in the CMAQ PM2.5 modeling domain for CAIR, EPA did not specifically assess impacts from New Mexico to downwind States. The commenter acknowledged that EPA conducted state by state "zero out" modeling for 37 states, but claimed that because EPA had not conducted such a zero36 out modeling run for New Mexico, the CMAQ model runs do not supportthe proposed conclusion in this action. 

### EPA Response

- EPA disagrees with the commenter'sjudgmentthat the technical analyses conducted in conjunction with CAIR do not provide technical support for the conclusion thatNew Mexico sources do not contribute significantly to violations ofthe 1997 PM2.5 NAAQS in any other state. EPA agrees that it progressively refined its analytical approach from the time ofthe proposed CAIR rule to the final CAIR rule, but it does not follow that the analyses done for CAIR are inappropriate for consideration in today's action. EPA believes that the analyses conducted for CAIR in fact provide technical supportto the conclusion that emissions from New Mexico sources do not contribute significantly to violations ofthese PM 2.5 NAAQS in any other state. EPA conducted modeling in the CAIRproposal using REMSAD modeling. With respect to the REMSAD modeling, the commenter is correctthat EPA specifically evaluated the impact ofemissions from New Mexico on other states in the eastern halfofthe United States. The modeling indicated a 0.03 ug/nr' maximum impact from New Mexico's emissions on downwind PM 2.5 nonattainment areas in 2010, which was significantly lowerthan the 0.15 J,lg/m3 value used as the threshold for significance in the proposed CAIR rule and the 0.20 J,lg/m3 value used in the final CAIR rule." In otherwords, EPA's analysis indicated that the impact ofemissions from New Mexico sources were only a small fraction ofthe initial threshold amount that EPA considered relevant as the first stage ofthe analysis to determine the existence of, and extent of, impact on other states.

31 See, Final CAIRrule 70 FR 25,162, at 25,174.37 The commenter implied that EPA's subsequentuse ofthe CMAQ model for the final CAIRrule per se renders REMSAD invalid for purposes oftoday's action. To supportthis assertion, the commenter overstatedthe potential limitations ofthe REM SAD model, a misimpression heightened by the way in which the commenterdescribed EPA's own stated position. The full statementby EPA in the final CAIR rule was32: "However, eventhough REMSAD does not have all the scientific refinements ofCMAQ, we believe that REMSAD treats the key physical and chemical processes associated with secondary aerosol formation and transport. Thus, we believe that the conclusions based on the proposal modeling using REMSAD are valid

..." This was not a categorical dismissal ofREMSAD modeling for all purposes; it was a recognition that REMSAD was reliable for certain purposes even though the subsequent CMAQ modeling

was an improvement. During rulemaking, it is appropriate for EPA to make improvements and refinements to models and the associated databases. EPA responded to comments raising

concerns about reliance on the REM SAD modeling results from the proposal package and determined that decisions and determinations based on the proposal REMSAD modeling were still valid in the final CAIR rule. With respect to the CMAQ modeling, New Mexico was not among the 37 states for which it did specific "zero out" modeling runs. EPA disagrees, however, with the commenter's extrapolation that this means EPA "did not assess" the impacts ofemissions from New Mexico with respect to the 1997 PM2.5 NAAQS in the final CAIR rule. To the contrary, EPA's evaluation ofNew Mexico with REMSAD was part ofthe analysis for the proposed CAIRrule and EPA did not reject the results ofthe REMSAD modeling in the final CAIR rule33• The lack

32 See, Final CAIRrule 70 FR 25,162, at 25234. 33 In this action, "CAIRProposal" refers to the proposal rule published on January 30, 2004 in the Federal Register and entitled "Rule to Reduce Interstate Transport ofFine Particulate Matter and Ozone", Interstate Air Quality Rule, 69 FR 4566.38 ofsignificant impact on nonattainment from New Mexico and other Western States shown by the REMSAD modeling in the proposal helped influence the more refined modeling analysis in the CAIR final rule which focused only on the Eastern States. In considering this comment, EPA has looked again at the use ofthe REMSAD modeling for the CAIRproposal for assessing New Mexico's impacts on other States. We continue to believe that the REMSAD results are sufficient to make a determination ofno significant contributionto nonattainment ofthe 1997 PM 2.5NAAQS in other states because ofthe very small impacts that were estimated from emissions from New Mexico sources. The REMSAD modeling had indicated that New Mexico's impacts on downwind 2010 PM 2.5 nonattainment areas was only 15% ofthe significance level used in the final CAIRrule. Because the REMSAD modeling indicated values ofonly 15% ofthe final significance level, EPA did not considerthe differences between the two modeling platforms (REMSAD and CMAQ) to be significant enough to lead to further analysis using CMAQ based modeling. EPA has determined in this action that the results from the REMSAD based modeling continue to supportthe conclusion that emissions from New Mexico sources are not contributing significantly to violations ofthe 1997 PM2.5 NAAQS in other states. The commenter did not articulate any way in whichthe distinctions between REMSAD and CMAQ would result in at least a seven-fold increase in the estimated impacts ofemissions from New Mexico emissions on another state's 1997 PM 2.5 nonattainment area. EPA does not believe that such a divergence would be likely. CommentNo. 

### 14 - The commenter argued that it is also inappropriate for EPA to rely on the CAIR modeling because the 2004 REMSAD model did not include other western states (including Arizona, California, Nevada, Utah, Idaho, Oregon, and Washington). The commenter asserted that EPA never assessed the impacts ofemissions from New Mexico to these western39 states in the CAIR modeling and that this is problematic because there are PM2.5 nonattainment areas in Californiaand in Utah. Although not clear, the commenter apparently argues that the existence ofdesignated PM2.5 nonattainment areas in California and Utah renders the CAIR modeling irrelevant. More specifically, the commenter argues that because EPA has recently designated certain counties in the Salt Lake City area and Cache County, Utah as nonattainment for the 2006 PM2.5 NAAQS, EPA was obligated to assess and limit downwind impacts accordingly in accordance with Section 110(1) ofthe Clean Air Act. 

### EPAResponse

- EPA disagrees with the commenteron this issue. First, this rulemaking addresses the potential impacts ofemissions from New Mexico sources on other states with violations ofthe 1997 PM 2.5 NAAQS, not the 2006 PM 2.5 NAAQS. Therefore, EPA's assessment ofNew Mexico's SIP was based on potential impacts on areas violating the 1997 PM 2.5 NAAQS (15**~g/m3** annual and 65**~g/m3** 24-hour standard). The application ofsection 11O(a)(2)(D)to the 2006 PM2.5 NAAQS, or other NAAQS, will be addressed in later actions that pertain to those NAAQS. Second, EPA believes that the analysis conducted in conjunction with CAIR is both relevant and very probative in evaluating the presence of, and extentof, interstate transport from New Mexico sources to other states in this action. The CAIR modeling and analysis specifically evaluated impacts on areas that were violating the 1997 PM 2.5 NAAQS. The other western states identified by the commenterwere in the CAIR modeling domain but were not evaluated further in the CAIR rule because, with the exception ofCalifornia and Montana, these states were in attainment ofthe 1997 PM2.5 NAAQS. 34 Absent areas with violations ofthose

34 See, Final CAIR rule 70 FR 25,162, at 25, I69:("Only two States in the western part ofthe U.S., California and Montana, have counties that exceeded the PM2.5 standards") and ("Because interstate transport is not believed to be40 NAAQS, there could be no significantcontribution to violations ofthe 1997 PM2.5 NAAQS. With regard to California and Montana, EPA indicated in the CAIR rule that interstate transport impacts were not a significant contributorto these areas, therefore impacts from New Mexico sources to Californiawere not Iikely." Finally, even aside from the CAIR analysis, EPA does not believe that emissions from New Mexico sources contribute significantly to violations ofthe 1997 PM2.5 NAAQS in California. The areas ofCaliforniawith violations ofthe 1997 PM2.5 NAAQS are generally located far to the west, hundreds ofmiles from New Mexico sources, across large expanses of mountain ranges that would impede transport, and generally upwind from New Mexico. EPA believes that the predominantmeteorological conditions would carry New Mexico emissions to the east, north, or south but not generally to the west. As a result, EPA concludes that it is very unlikely that New Mexico's emissions transport hundreds ofmiles to the west to the 1997 PM 2.5 NAAQS in California.36 The CAIR modeling only addressed areas that were expectedto be innonattainment in 2010, based on existing monitoring data at the time and 2010 photochemical modeling. Other than California, none ofthe other states mentioned by the commenter were monitoring nonattainment, or designated nonattainment for the 1997 PM 2.5 standards, at the time these analyses were conducted. Although not cited by the commenter, EPA notes that there has been one monitored violation ofthe 1997 PM 2.5 annual NAAQS in Utah. It occurred in 2002-2004 time period at a single monitor in the Salt Lake City area. This violation has not continued. In this instance, the

a significant contributor to exceedances ofthe PM2.5 standards in California or Montana, today's fmal CAIR does not cover these States")

3S ld. 36 EPA reached this same conclusion in the CAIRrule. See, Final CAIR rule 70 FR 25,162, at 25,169.41 state concluded thatthe monitor was heavily impacted by a nearby source. After the state instituted controls at the source, the design value has dropped to less than 45 ug/nr' in the last four years. EPA notes that the impact ofa nearby source does not in and ofitselfnegate the possibility ofimpacts ofinterstate transport at that monitor as well. However, because that monitor has not subsequently shown any violation ofthe 1997 PM2.5 NAAQS, EPA concludes that there are no areas in Utah with violations ofthatNAAQS to whichNew Mexico sources could be contributing significantly. All other PM 2.5 monitors in the area have consistently had DVs below 55 J..lg/m3 since the 2001-2003 DV period. CommentNo. 

### 15 -The commenter also criticized modeling thatthe state and EPA relied upon because ofconcerns about the accuracy ofthe underlying emissions inventories on which the models relied. In particular, the commenter claimed thatthe modeling fails to address recent growth in emission inventories for oil and gas operations in New Mexico that have been raising the emissions from the state higher than have been previously reported in emissions inventories. The commenter argued that these increases in emissions at least call into question the accuracy ofthe modeling relied upon by EPA to supportthe proposed approval ofthe State's submission, and at worst demonstrate that EPA has failed to address a key aspect ofcontribution to nonattainment in downwind states from New Mexico sources. The commenter listed several recent reports that estimated increased emissions ofS02, NOx, and VOCs that result from the growth ofoil and gas exploration in certain areas in New Mexico. The more recent studies cited by the commenter were:

• The November 25, 2009 inventory of2006 oil and gas emissions in the San Juan Basin ofNew Mexico, which includes San Juan, Rio Arriba, McKinley, and Sandoval Counties, prepared by the IndependentPetroleum Association ofthe Mountain States42 ("IPAMS"). This inventory found that oil and gas point and area sources within this region annually released 42,075 tons ofNOx, 60,697 tons ofvolatile organic compounds ("VOCs") and 305 tons ofsulfur dioxide ("S02").; • The August 2009 report on 2005 emissions in the Four Corners region ofnorthwesternNew Mexico, which found that oil and gas point and area sources within the region annually released 57,682 tons ofNOx, 668 tons ofS02, and 117,370 tons ofVOCs. The report indicates that by 2018, these emissions will increase to 65,543 tons ofNOx, 670 tons ofS02, and 143,050 tons of VOCs; and • The 2007 WRAP Phase II Inventory of2002 oil and gas emissions, which found that oil and gas activities throughoutNew Mexico released 112,540 tons ofNOx and 13,925 tons ofS02, and that by 2018 would release 110,034 tons ofNOx and 13,002 tons of S02 in the State. The commenter argued that without specifically addressing these more recent increases in the emissions associated with oil and gas development, New Mexico and EPA have no basis to conclude that the modeling relied upon in the proposed approval is accurate or ensures that emission are not and will not significantly contribute to nonattainrnent in other states. The commenter also noted that the modeling prepared for CAIRutilized emission inventories from 2001, which would likewise fail to account for the more recent increase in emissions associated with oil and gas development 

### EPA Response

- EPA shares the commenter's concern with emissions from oil and gas development, and agrees that dramatic increases in such emissions, and especially emissions from sources that are not appropriately controlled, have the potential to contribute significantly to violations ofNAAQS in other states. However, EPA has investigated this issue in response to43 the commenter's concerns in this action, and has concluded that the information currently available does not indicate thatNew Mexico's emissions from oil and gas development are significantly contributing to violations ofthe 1997 8-hour ozone NAAQS and 1997 PM2.5 NAAQS in other states. To reach this conclusion, EPA has used available information and extrapolated whatthe impacts ofthe additional emissions from oil and gas development would be in a worst case scenario, as part ofevaluating how those increases would affect the modeling results and other information EPA relied upon in the proposal. EPA has to make regulatory decisions using the emissions inventories and analyses that

are available at the time ofthe decision. These inventories are, ofcourse, constantly being updated and refined. The CAIR modeling used a base year emission inventory from 2001 that EPA then projected to 2010, which was the timeframe thatEPA used for the analysis ofNew Mexico's impacts on areas in other states with monitors projectedto have violations ofthe 1997 PM 2.5 NAAQS. The CENRAP modeling used a 2002 inventory to assess New Mexico's ozone impacts on areas in other states with monitors projectedto have violations ofthe 1997 8-hour

ozone NAAQS. At the time this modeling was conducted, EPA believedthat the emission estimates for oil and gas development were appropriate. The commenter cited studies thathave been conducted more recently to refine estimates ofcurrent emissions and future projected emission levels from oil and gas development in areas ofNew Mexico. These more recent studies indicate that emissions from oil and gas development are likely much higher than those assumed in the models. Because the studies do not indicate the amount ofemissions growththat has happened since the 200112002timeframe, however, it is difficultto determine the impactthis presumed increase would have. Therefore, to evaluate this concern, below we consider a worst case estimate impact ofoil and gas emissions44 on whether emissions from sources in New Mexico significantly contribute to nonattainment in other states. The reports cited by the commenter indicate that emissions from all oil and gas development in New Mexico in the years from 2002-2006 have a range ofup to 112,540 tpy of NOx, 117,370 tpy ofVOC, and 13,925 tpy ofS02. In comparison, the modeling conducted using the 2002 CENRAP emission inventory databases included emissions from all sources in New Mexico with totals of306,194 tpy ofNOx, 1,749,081 tpy ofVOC and 100,174 tpy of S02.37 The modeling conducted for CAIR included an inventory from all sources of242,782 tpy ofNOx and 173,724 tpy ofS02 for the 2010 base level emissions for sources in New Mexico.P These emissions inventories used for the CENRAP modeling and the CAIR modeling did include some emissions from oil and gas development activities in New Mexico, so EPA believes that some portion of emissions attributed to such sources in the more recent studies

were included in statewide emission inventories from all sources and thus in the CENRAP and CAIR modeling. It would be very difficultto ascertain the exact amount ofemissions from oil and gas sources that were included in the emission inventories for these two modeling evaluations and thus to ascertain the exact amountthat the inventories used for the modeling exercises underestimate such emissions. Therefore, to evaluate how much the additional emissions from oil and gas development could impactthe determination, we have used a worst case estimate of how much higher the emissions in New Mexico could be, based on the studies provided by the commenter. Ifone uses the highestNOx value from these reports of 112, 540 tpy and compare

37 WRAP EDMS, CENRAP TSD 38 CAIR Proposal TSD45 that with the 306,194 tpy ofNOx (from the CENRAP based modeling), the percentage increase in NOx emissions would be a 36% increase in NOx emissions over the modeled emissions. Similarly, ifone compares the highest S02 value from the reports (using 13,925 tpy from the reports and 100,174 tpy from the CENRAP based modeling) the percentage increase in S02 emissions would be less than a 8 % increase in S02 emissions over the modeled emissions. EPA believes that these are worst case scenario increases, because they include the highest estimate ofoil and gas development emission from the reports supplied by the commenter, but they probably overestimate the true increase over the inventories used for the modeling, and double count the emissions ofoil and gas that were in the original modeling. EPA notes that these estimates also do not include the significantreductions that have occurred in New Mexico from non oil and gas sectors, such as federal motor vehicle controls and fleet turn over and controls on S02 and NOx emissions installed on large stationary sources including the San Juan Generating Station. In addition, emissions in other parts ofthe modeling domain outside ofNew Mexico wouldbe expected to have decreased after 2002 due to federal and state controls including fleet turnover and would not have been included in the CENRAP based modeling for ozone and only partially included in the CAIRmodeling.

EPA relied on photochemical modeling conducted for CAIRfor the PM 2.5 analysis in determining that New Mexico's emissions do not make a significant contribution in areas in other states with monitors showing violations ofthe 1997 PM 2.5 NAAQS. As discussed elsewhere in this notice, the modeling indicated that the largest impact from New Mexico's emissions on any such monitor in another state was only 15% ofthe significance level used in the final CAIRrule. In the worst case estimate above, NOx emissions could at mostbe 36%

### 46 higher and S02 could be at most 8% higherthan was modeled in CAIR. Although the impact on the model would not necessarily be linear, EPA does not believe that such arelatively small increase in total S02 and NOx emissions would increase the impact ofNew Mexico emissions by the more than 7 fold necessary to reach the significance level EPA used in CAIR for the 1997 PM2.5 NAAQS. EPA relied on photochemical modeling based on 2002 emission inventories (available from CENRAP's efforts) in determining that New Mexico's emissions do not make a significant contribution in areas in other states with monitors showing violations ofthe 1997 8-hour ozone NAAQS. EPA relied on this modeling to evaluate the possible contribution from New Mexico sources to areas that were monitoring violations ofthe 1997 8-hour NAAQS. EPA considers the modeling conservative in that it used 2002 inventories, and for the entire modeling grid (which covered most ofthe continental

# u.s. and parts ofCanada and Mexico), and it did not include the benefits from emissionreductions after 2002 from federal and state requirements including fleet turnover. The modeling did not indicate values that were close to the significance levels for New Mexico's impacts on out ofstate areas which were nonattainment and/or monitoring nonattainment ofthe 1997 8-hour ozone NAAQS. The area monitoring nonattainment with the highest modeled impact from sources inNew Mexico was the DallaslFort Worth Area. The modeled daily average contribution from sources in New Mexico was 0.4% with a contribution average of0.4 ppb. EPA's screening criteria for the first step ofthe analysis for any significant contribution, established in CAIR and upheld by the court, were 1% and 2 ppb respectively. EPA believes that even a conservative estimate ofa 36% increase inNOx emissions from New Mexico's sources would not more than double New Mexico's impacton other states, even before considering the otheroffsetting NOx emission reductions between 2002 and 2010 from other

### 47 source categories. Therefore, EPA concludes that these new emission estimates would not result in significant enough changes in impacts from New Mexico's sources to change the determinationthat emissions from sources in New Mexico do not significantly contribute to violations ofthe 1997 8-hour ozone NAAQS in other states, based on available information. Accordingly, New Mexico does not need to amend its SIP substantively to reduce any additional emissions to prevent such impacts on other states. Finally, EPA notes that photochemical modeling is a very detailed and complicated process and there are continual refinements in emission inventories and othermodeling databases. Unfortunately, the statutory and regulatory requirements, and especially the timing requirements, for developing and evaluating SIPs do not allow for time or resources to do every possible refinement to emission inventories on a continual basis. In this specific case, EPA agrees that the sudden expansion ofoil and gas development and the emissions increases from such activities are a source category for which emissions inventories need updating, to insure that future regulatory actions by both states and EPA continue to be based upon the most recent and accurate information available EPA is concerned with the growth in emissions from oil and gas development in New Mexico and other areas ofthe country, including other states in Region 6. On May 10,2010, EPA Region 6 held a meeting with the principal oil and gas producers, trade organizations, and the five States in the Region, with the goal offinding ways to improve the emission inventory for these sources. Region 6 has initiated this process because a clearerunderstanding ofthese emissions will be necessary for future air quality plans underthe new revised standards.48 CommentNo. 16 - The commenter also objectedto EPA's proposed approval because "New Mexico's SIP, as written, simply does not contain any language that prohibits emissions that contribute significantly to nonattainment in any other state." The commenter also noted that EPA did not assess whetherthe SIP does or does not contain such provisions. The commenter appears to have argued that 11O(a)(2)(D)(i) requires a state SIP to contain an explicitprovision literally prohibiting emissions that contribute significantly to nonattainment in any other state and that, in orderto approve the New Mexico interstate transport SIP, EPA must examine the SIP to determine whether it contains such an explicitprohibition. EPA Response

- EPA disagrees with the commenter's interpretation ofthe statutory requirements. Section 110(a)(2)(D)(i) has no language that requires a SIP to contain a specific provision literally prohibiting significant contributionto nonattainment in any other state or, for that matter, to contain any particularwords or generic prohibitions. Instead, EPA believes that the statute requires a state's SIP to contain substantive emission limits or other provisions that in fact ensure that sources located within the state will not produce emissions thathave such an effect in other states. Therefore, EPA believes that satisfaction ofthe "significant contribution" requirement is not to be demonstrated through a literal requirement for a prohibition ofthe type advocated by the commenter. EPA's past application ofsection 11 O(a)(2)(D) did not require the literal prohibition advocated by the commenter. For example, in the 1998 NOx SIP Call39• EPA indicated that "the term 'prohibit' means that SIPs must eliminate those amounts ofemissions determined to contribute significantly to nonattainment

...." As a result, the first step ofthe process to determine whether this statutory requirement is satisfied is the factual determination ofwhether

39 63 FR 57356, October 27, 1998

### 49 emissions from sources in the state contribute significantly to nonattainment in downwind areas'". Ifthis factual finding is in the negative, as is the case for EPA's assessment ofthe contribution from emissions from sources in New Mexico, then section 11O(a)(2)(D)(i)(I) does not require any changes to the state's SIP. If, however, the evaluationreveals that there is such a significant contributionto nonattainment in other states, then EPA requires the state to adopt substantive provisions to eliminate those emissions. The state could achieve these reductions through traditional command and control programs, or at its own election, through participation in another mechanism such as the cap and trade program ofthe NOx SIP Call. Thus, EPA's approach in this action is consistentwith the Agency's interpretation of 11O(a)(2)(D)(i) in the 2006 guidance, the CAIR Rule, and the NOx SIP Call, none ofwhich required theproforma literal "prohibition" ofthe type advocated by the commenter. CommentNo. 

### 17 - The commenter noted a specific provision for stationary source permitting in the New Mexico SIP that the commenterargued is inadequate to ensure that sources in New Mexico will not significantly contribute to nonattainment in other states. According to the commenter, New Mexico has a regulatory provisionthat requires the state agency to deny an application for a permit or permitrevision for a stationary source under certain circumstances, including the violation ofany NAAQS. The commenter claimedthat New Mexico interprets this authority to allow the denial ofsuch a permit, only ifthe source is physically located in a designated nonattainment area. EPA Response

- EPA disagrees with the commenter's characterization ofthe State's regulations that New Mexico can only deny apermit for new or modified sources located in a designated nonattainment area. EPA has reviewed the New Mexico permitting provisions cited

40 See 2005 CAIR Rule (70 FR 25162) and 1998 NOx SIP Call (63 FR 5735650 by the commenter. Section 20.2.72.208 NMAC contains the reasons the department must deny a pennit. Section 20.2.72.208 D explicitly provides that one ofthe reasons the State will deny a pennit is if"the construction, modification, or permitrevision will cause or contribute to air contaminant levels in excess ofany National AmbientAir Quality Standard or New Mexico Ambient Air Quality Standard unless the ambient air impact is offsetby meeting the requirements ofeither 20.2.79 NMAC or 20.2.72.216 NMAC, whichever is applicable." Section 20.2.79 NMAC and 20.2.72.216 NMAC apply in nonattainment areas which have more stringent requirements than attainment areas. EPA believes that the provisions ofSection 20.2.72.208 NMAC apply in attainment areas ofthe State and are unambiguous. The state's regulations provide that it "shall deny" a permit for a source located in an attainment area, ifthat new or modified source would cause or contribute to air contaminant levels that exceed any NAAQS, whether those violations occur in New Mexico or elsewhere. To verify this understanding ofthe state's regulations, EPA contacted NMED regarding this comment. NMED responded with an E-mail that is included in the docket for this rulemaking confirming thatthe provisions of20.2.72.208 NMAC apply in the attainment areas ofthe State and provide for denial ofpermits ifthe construction, modification

or revision will cause or contribute to levels in excess ofthe NAAQS. CommentNo. 

### 18 - The commenter argued that EPA cannot approve the section 110(a)(2)(D) submission from New Mexico because the State and EPA did not comply with the requirements ofsection 11O(l). Evidently, the commenterbelieves that the section 110(a)(2)(D) submission for the 1997 8-hourozone and 1997 PM2.5 NAAQS is a revision to the SIP that will interfere with attainment ofthe 2006 PM2.5 NAAQS and the 2008 ozone NAAQS. The commenter argued that a section 110(1)analysis must consider all NAAQS once they are51 promulgated, and argued that EPA recently tookthe same position in proposing to disapprove a PMIO maintenance plan. EPA Response - EPA agrees that a required section 110(1) analysis must considerthe potential impact ofa proposed 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) in this action or that section 110(1)requires disapproval ofthe SIP submission at issue here. Section 110(1)provides in partthat: "the 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 concludedthatpreservation 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 FR 53, 57 (Jan. 3, 2005); 70 FR 28,429,28,431 (May 18, 2005). New Mexico's submission is the initial submission by the State to address the significant contribution to nonattainmentelement of 110(a)(2)(D)(i) for the 1997 8-hour ozone and 1997 PM2.5NAAQS. This submission does not revise or remove any existing emissions limit for any NAAQS, or change any other existing substantive SIP provisions relevant to the 1997 8-hour

ozone or 1997 PM2.5NAAQS or any otherNAAQS. Simply put, it does not make any substantive revision that could result in any change in emissions. As a result, the submission52 does not relax any existing requirements or alter the status quo air quality. Therefore, approval ofthe submission will not interfere with attainment or maintenance ofany NAAQS. EPA's discussion in the notice cited by the commenter concerning a PMIO maintenance plan in another state is consistent with this interpretation. In the cited action, EPA noted that: "Utah had either removed or altered a number ofstationary source requirements," creating the possibility ofa relaxation ofexisting EPA approved SIP requirements and thereby interfering with attainment, a possibility that is not present here. See 74 FR 62727 (Dec. 1,2009). Thus, the action cited by the commenter is clearly distinguishable. The commenter did not provide any specific basis for concluding that approval ofthis SIP submission would interfere with attainment or maintenance ofany NAAQS, or with 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 with the development ofan overall plan capable ofmeeting the Act's attainment requirements. In particular, EPA has determined that the submission complies with the requirements ofsection 110(a)(2)(D)(i). Accordingly, assuming that section 110(1) applies to this SIP submission, EPA finds that approval ofthe submission is consistentwith the requirements ofsection 110(1). CommentNo. 

### 19 -- In a separate comment letter, the commenter expressed concern with EPA's proposed approval ofthe State's submission for the 1997 8-hour ozone NAAQS and 1997 PM2.5 NAAQS because the state "does not appropriately limit ozone" in its PSD permitting program. To supportthis claim, the commenter noted that EPA has previously made a "finding offailure to submit" because New Mexico had not made another submission that would have the effect ofmaking NOx a regulatory precursor for ozone in the context ofPSD. According to the commenter, EPA should not approve the state's submission for section 11O(a)(2)(D)(i)(I) for the

### 53 significant contribution to nonattainmentrequirementbecause ofthis outstanding obligation with respectto the PSD requirements ofthe CAA for the 1997 8-hour ozone NAAQS. EPA Response

- EPA acknowledges that it made the finding offailure to submit noted by the commenter.I' However, EPA disagrees with the commenter's view ofhow that prior finding affects today's specific action. First, the "finding offailure to submit" to which the commenter refers is not for a failure to make a submission with respect to section 110(a)(2)(D). In that prior action, EPA made a formal finding that the state had, at that time, not yet made a different SIP submission, necessary to comply with a separate requirements ofsection 11O(a)(2)(C)and section 1l0(a)(2)(J). Second, EPA believes that the cited finding offailure to submitdoes not relate to the requirements ofsection 

### II0(a)(2)(D)(i)(I) with respectto significant contribution to nonattainment at issue in this action, but rather to the separate requirements ofsection 11O(a)(2)(D)(i)(II) that SIPs include measures to prevent interference with measures required for "prevention ofsignificant deterioration." EPA's 2006 Guidance explainedthe Agency's views ofwhat the four separate and distinct elements ofsection 11O(a)(2)(D)require.42 EPA's guidance made recommendations to states for making submissions to meet each ofthe separate requirements ofsection 11O(a)(2)(D) for the 1997 8-hour ozone standards and 1997 PM2.5 standards. Within the guidance, EPA recommended that states evaluate the existence of, and extentof, significant contribution to nonattainment in other states by various means, intended to considerrelevant facts about such contribution to nonattainment. By contrast, EPA

41 See, Completeness Findings for Section 110(a)(2) State Implementation Plans for the 8-hour Ozone NAAQS, 73 FR 16,205 (March 28, 2008). 42 "Guidance for State Implementation Plan (SIP) Submission to Meet Current Outstanding Obligations Under Section 110(a)(2)(D)(i) for the 8-Hour Ozone and PM 2.sNational Ambient Air Quality Standards" August 15, 2006.54 recommended that states meet the separate requirement that their SIPs contain measures to prevent interference with measures required to prevent significant deterioration ofair quality in other states by different means. In particular, EPA explained that this latter element ofsection 110(a)(2)(D) would be the correct context in which to confirmthat the state in question had updated its own SIP to contain measures related to PSD. In the 2006 Guidance, EPA explicitly identified the regulatory requirements and separate SIP revision necessary to implementthe PSD program for the 1997 8-hour ozone NAAQS as among the requirements that EPA considered relevant to the prevention ofsignificant deterioration requirements ofsection 110(a)(2)(D).43 EPA stated its view that implementation of the PSD permitting program within the state would address the requirement to prohibit emissions that interfere with measures to prevent significant deterioration in neighboring states. EPA also explained that the permitting program for the 8-hourozoneNAAQS would require that new or modified sources will not cause or contribute to violations ofthe NAAQSin neighboring states,

so that additional SIP submissions with rule changes or modeling demonstrations would notbe required to establish that a state's program complies with the requirementin section 11O(a)(2)(D)(i)(II) In short, EPA believes that evaluation ofa state's SIP for compliance with section 11O(a)(2)(D)(i)(II) is the proper context in whichto determine whether such SIP meets current federal PSD requirements. Today's action does not address this element ofsection 11O(a)(2)(D), and accordingly, the finding offailure to submit is not a basis not to approve the State's submission for this purpose. Finally, EPA notes that the State ofNew Mexico has subsequently made a submission to comply with the rule that was the basis for the finding offailure to submitcited by the

43 Id, at pages 6 - 8.

### 55 commenter. EPA is in the process ofevaluating that submission and will act on it at a laterdate. EPA anticipates that it may electto act upon that separate submission at the same time it acts upon the state's section 11O(a)(2)(D) submission for the prevention ofsignificant deterioration requirement, as EPA has recently done in the case ofthe section 11O(a)(2)(D) submission for the State ofNorth Dakota.

B. Comments from New Mexico Environment Department, Air Quality Bureau 

### CommentNo.1

- The commenter statedthat while it did not objectto EPA's proposed approval ofthe "contribute to nonattainment" prong ofsection 11O(a)(2)(D)(i) ofthe CAA, it believed that EPA should have approved the SIP submission as meeting all prongs ofthat section. The commenter asserted its beliefthatNew Mexico satisfied all requirements ofsection 110(a)(2)(D) for the 1997 8-hour ozone and 1997 PM2.5 NAAQS in its submission, following EPA's recommendations in the 2006 Guidance for this SIP revision. 

### EPA Response

- We appreciate NMED's comments. At this time, EPA is only taking action on the portions ofthe State's submissionthat pertain to the significant contribution to nonattainment requirements ofsection 11O(a)(2)(D) for the 1997 8-hourozone and 1997 PM2.5 NAAQS. EPA will act on the remaining requirements ofsection 110(a)(2)(D) for these NAAQS at a later date.

IV. Final Action We are approving one element ofthe Interstate Transport SIP submitted by the State of New Mexico on September 17, 2007. Specifically, in this action we are approving the element that addresses the requirement ofSection 110(a)(2)(D)(i)(I) that emissions from sources in that56 state do not "contribute significantly" to violations of the 1997 8-hour ozone or 1997 PM2.5 NAAQS in any other state. After fully considering all comments received on the proposal and direct final rule EPA has concluded that the State's submission, and additional evidence evaluated by EPA, establishthat emissions from New Mexico sources do not contribute significantly to nonattainment ofthe relevantNAAQAS in any other state. Accordingly, New Mexico does not need to include additional emission limitations on its sources to eliminate any such contribution to other states for purposes ofthese NAAQS. At a later date, EPA will act on addressing the remaining requirements ofsection 11O(a)(2)(D)(i)which are: interference with the maintenance ofthe NAAQS in any other state; interference with measures required to prevent significantdeterioration ofair quality in any other state; and interference with measures required to protect visibility in any other state.



### V. Statutory and Executive OrderReviews Under the Clean Air Act, the Administrator is required to approve a SIP submission that complies with the provisions ofthe Act and applicable Federal regulations. 42 U.S.C. 741O(k); 40 CFR 52.02(a). Thus, in reviewing SIP submissions, EPA's role is to approve state choices, providedthat they meet the criteriaofthe Clean Air Act. Accordingly, this action merely approves state law as meeting Federal requirements and does not impose additional requirements beyond those imposedby state law. For that reason, this action: • is not a "significantregulatory action" subject to review by the Office ofManagement and Budget under Executive Order 12866 (58 FR 51735, October 4, 1993);57 • does not impose an information collection burden underthe provisions ofthe Paperwork Reduction Act (44 U.S.C. 3501 et seq.); • is certified as not having a significanteconomic impact on a substantial number ofsmall entities under the Regulatory Flexibility Act (5 U.S.C. 601 et seq.); • does not contain any unfunded mandate or significantly or uniquely affect small governments, as described in the Unfunded Mandates Reform Act of 1995 (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 subjectto Executive Order 13045 (62 FR 19885, April 23, 1997); • is not a significant regulatory action subjectto Executive Order 13211 (66 FR 28355, May 22,2001); • is not subjectto 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 Air Act; and • does not provide EPA with the discretionary authority to address, as appropriate, disproportionate human health or environmental effects, using practicable and legally permissible methods, under Executive Order 12898 (59 FR 7629, February 16, 1994). In addition, this rule does not have tribal implications as specifiedby Executive Order 13175 (65 FR 67249, November 9,2000), because the SIP is not approved to apply in Indian country located in the state, and EPA notes that it will not impose substantial direct costs on tribal governments or preempt tribal law.58 The Congressional Review Act, 5 U.S.C. 801 

### et seq., as added by the Small Business Regulatory Enforcement Fairness Act of 1996, generally provides thatbefore 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 other required 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 rule cannottake effect until 60 days after it is published in the Federal Register. This action is not a "major rule" as defined by 5 U.S.C. 804(2). Under section 307(b)(l) ofthe Clean Air Act, petitions forjudicial review ofthis action mustbe filed in the United States Court ofAppeals for the appropriate circuitby [FEDERAL REGISTER OFFICE: insert date 60 days from date ofpublication of this document in the Federal Register]. Filing a petition for reconsideration by the Administrator ofthis final rule does not affectthe 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).)

### 59

List ofSubjects in 40 CFR Part 52 Environmental protection, Air pollution control, Incorporation by reference, Intergovernmental relations, Ozone, Particulate matter, Reporting and recordkeeping requirements, Volatile organic compounds.

Dated:

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# ~}. 

# r;:;;:::LJ

wrence E. Starfield Acting Regional Administrator, Region 6.40 CFR Part 52 is amended as follows: 

### PART 52 - [AMENDED] 1. The authority citation for part 52 continues to read as follows: Authority: 42 U.S.C. 7401 et seq. Subpart GG - New Mexico 2. The second table in 

### § 52.1620(e) entitled "EPA Approved Nonregulatory Provisions and Quasi-Regulatory Measures in the New Mexico SIP" is amended by adding an entry to the end to read as follows: 

### § 52.1620 Identification ofplan.



## * * * * * (e) 

## * * * EPA Approved Nonregulatory Provisions and Quasi-Regulatory Measures in the New Mexico SIP

State Applicable geographic submittal/effective Name ofSIP provision or nonattainment area date EPA approval date Explanation 

## ••••••• Interstate transport for New Mexico 09117/07 [insert date ofFR [insert date ofFR the 1997 ozone and publication] publication] PM 2.sNAAQS [insert FR page Approval for number where the documentbegins] revisions to prohibit significant contribution to nonattainment in any other state