2015-03573. Approval and Promulgation of Implementation Plans; Idaho: Interstate Transport of Fine Particulate Matter

AGENCY:

Environmental Protection Agency.

ACTION:

Proposed rule.

SUMMARY:

The Clean Air Act (CAA) requires each State Implementation Plan (SIP) to contain adequate provisions prohibiting air emissions that will have certain adverse air quality effects in other states. On June 28, 2010, the State of Idaho submitted a SIP revision to the Environmental Protection Agency (EPA) to address these interstate transport requirements with respect to the 2006 24-hour fine particulate matter (PM_2.5) National Ambient Air Quality Standards (NAAQS). The EPA is proposing to find that Idaho has adequately addressed certain CAA interstate transport requirements for the 2006 24-hour PM_2.5 NAAQS.

DATES:

Written comments must be received on or before March 25, 2015.

ADDRESSES:

Submit your comments, identified by Docket ID No. EPA-R10-OAR-2013-0581, by any of the following methods:

• www.regulations.gov: Follow the on-line instructions for submitting comments.
• Email: [e-mail].
• Mail: Kristin Hall, EPA Region 10, Office of Air, Waste and Toxics (AWT-150), 1200 Sixth Avenue Suite 900, Seattle, WA 98101.
• Hand Delivery/Courier: EPA Region 10 9th Floor Mailroom, 1200 Sixth Avenue Suite 900, Seattle, WA 98101. Attention: Kristin Hall, Office of Air, Waste and Toxics, AWT—150. Such deliveries are only accepted during normal hours of operation, and special arrangements should be made for deliveries of boxed information.

Instructions: Direct your comments to Docket ID No. EPA-R10-OAR-2013-0581. The EPA's policy is that all comments received will be included in the public docket without change and may be made available online at www.regulations.gov,, including any personal information provided, unless the comment includes information claimed to be Confidential Business Information (CBI) or other information whose disclosure is restricted by statute. Do not submit information that you consider to be CBI or otherwise protected through www.regulations.gov or email. The www.regulations.gov Web site is an “anonymous access” system, which means the EPA will not know your identity or contact information unless you provide it in the body of your comment. If you send an email comment directly to the EPA without going through www.regulations.gov your email address will be automatically captured and included as part of the comment that is placed in the public docket and made available on the Internet. If you submit an electronic comment, the EPA recommends that you include your name and other contact information in the body of your comment and with any disk or CD-ROM you submit. If the EPA cannot read your comment due to technical difficulties and cannot contact you for clarification, the EPA may not be able to consider your comment. Electronic files should avoid the use of special characters, any form of encryption, and be free of any defects or viruses.

Docket: All documents in the docket are listed in the www.regulations.gov index. Although listed in the index, some information is not publicly available, e.g., CBI or other information the disclosure of which 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. Publicly available docket materials are available either electronically in www.regulations.gov or in hard copy during normal business hours at the Office of Air, Waste and Toxics, EPA Region 10, 1200 Sixth Avenue, Seattle, WA 98101.

FOR FURTHER INFORMATION CONTACT:

Kristin Hall at [phone], [e-mail], or the above EPA, Region 10 address.

SUPPLEMENTARY INFORMATION:

Throughout this document wherever “we,” “us,” or “our” is used, it is intended to refer to the EPA. Information is organized as follows:

Table of Contents

I. Background

A. 2006 24-Hour PM_2.5 NAAQS and Interstate Transport

B. Rules Addressing Interstate Transport for the 2006 24-Hour PM_2.5 NAAQS

C. Guidance

II. State Submittal

III. EPA Evaluation

A. Identification of Nonattainment and Maintenance Receptors

B. Evaluation of Significant Contribution to Nonattainment

C. Evaluation of Interference With Maintenance

IV. Proposed Action

V. Statutory and Executive Order Reviews

I. Background

A. 2006 24-Hour PM_2.5 NAAQS and Interstate Transport

On September 21, 2006, the EPA promulgated a final rule revising the 1997 24-hour primary and secondary NAAQS for PM_2.5 from 65 micrograms per cubic meter (µg/m³) to 35 µg/m³ (October 17, 2006, 71 FR 61144). Section 110(a)(1) of the CAA requires each state to submit to the EPA, within three years (or such shorter period as the Administrator may prescribe) after the promulgation of a primary or secondary NAAQS or any revision thereof, a SIP that provides for the “implementation, maintenance, and enforcement” of such NAAQS. The EPA refers to these specific submittals as “infrastructure” SIPs because they are intended to address basic structural SIP requirements for new or revised NAAQS. For the 2006 24-hour PM_2.5 NAAQS, these infrastructure SIPs were due on September 21, 2009. CAA section 110(a)(2) includes a list of specific elements that “[e]ach such plan submission” must meet.

The interstate transport provisions in CAA section 110(a)(2)(D)(i) (also called “good neighbor” provisions) require each state to submit a SIP that prohibits emissions that will have certain adverse air quality effects in other states. CAA section 110(a)(2)(D)(i) identifies four distinct elements related to the impacts of air pollutants transported across state lines. In this action, the EPA is addressing the first two elements of this section, specified at CAA section 110(a)(2)(D)(i)(I),^[1] for the 2006 24-hour PM_2.5 NAAQS.

The first element of CAA section 110(a)(2)(D)(i)(I) requires that each SIP for a new or revised NAAQS contain adequate provisions to prohibit any source or other type of emissions activity within the state from emitting air pollutants that will “contribute significantly to nonattainment” of the NAAQS in another state. The second element of CAA section 110(a)(2)(D)(i)(I) requires that each SIP contain adequate provisions to prohibit any source or other type of emissions activity in the state from emitting air pollutants that will “interfere with maintenance” of the applicable NAAQS in any other state.

B. Rules Addressing Interstate Transport for the 2006 24-Hour PM_2.5 NAAQS

The EPA has addressed the interstate transport requirements of CAA section 110(a)(2)(D)(i)(I) in past regulatory actions.^[2] The EPA promulgated the final Cross-State Air Pollution Rule (Transport Rule) to address CAA section 110(a)(2)(D)(i)(I) in the eastern portion of the United States with respect to the 2006 PM_2.5 NAAQS, the 1997 PM_2.5 NAAQS, and the 1997 8-hour ozone NAAQS (August 8, 2011, 76 FR 48208). The Transport Rule was intended to replace the earlier Clean Air Interstate Rule (CAIR) which was judicially remanded.^[3] See North Carolina v. EPA, 531 F.3d 896 (D.C. Cir. 2008). On August 21, 2012, the U.S. Court of Appeals for the D.C. Circuit issued a decision vacating the Transport Rule. See EME Homer City Generation, L.P. v. E.P.A., 696 F.3d 7 (D.C. Cir. 2012). The Court also ordered the EPA to continue implementing CAIR in the interim. However, on April 29, 2014, the U.S. Supreme Court reversed and remanded the D.C. Circuit's ruling and upheld the EPA's approach in the Transport Rule for the issues that were in front of the Supreme Court for review.^[4] On October 23, 2014, the D.C. Circuit lifted the stay on the Transport Rule.^[5] While our evaluation is consistent with the Transport Rule approach, the State of Idaho was not covered by either CAIR or the Transport Rule, and the EPA made no determinations in either rule regarding whether emissions from sources in Idaho significantly contribute to nonattainment or interfere with maintenance of the 2006 24-hour PM_2.5 NAAQS in another state, nor did it attempt to quantify Idaho's obligation.^[6]

C. Guidance

On September 25, 2009, the EPA issued a guidance memorandum that addressed the requirements of CAA section 110(a)(2)(D)(i) for the 2006 24-hour PM_2.5 NAAQS (“2006 24-hour PM_2.5 NAAQS Infrastructure Guidance” or “Guidance”).^[7] With respect to the requirement in CAA section 110(a)(2)(D)(i)(I) that state SIPs contain adequate provisions prohibiting emissions that would contribute significantly to nonattainment of the NAAQS in any other state, the 2006 24-hour PM_2.5 NAAQS Infrastructure Guidance essentially reiterated the recommendations for western states made by the EPA in previous guidance addressing the CAA section 110(a)(2)(D)(i) requirements for the 1997 8-hour ozone and 1997 PM_2.5 NAAQS.^[8] The 2006 24-hour PM_2.5 NAAQS Infrastructure Guidance advised states outside of the CAIR region to include in their CAA section 110(a)(2)(D)(i)(I) SIPs adequate technical analyses to support their conclusions regarding interstate pollution transport, e.g., information concerning emissions in the state, meteorological conditions in the state and in potentially impacted states, monitored ambient pollutant concentrations in the state and in potentially impacted states, distances to the nearest areas not attaining the NAAQS in other states, and air quality modeling.^[9] With respect to the requirement in CAA section 110(a)(2)(D)(i)(I) that state SIPs contain adequate provisions prohibiting emissions that would interfere with maintenance of the NAAQS by any other state, the Guidance stated that SIP submissions must address this independent requirement of the statute and provide technical information appropriate to support the state's conclusions, such as information concerning emissions in the state, meteorological conditions in the state and in potentially impacted states, monitored ambient concentrations in the state and in potentially impacted states, and air quality modeling. See footnotes 5 and 6.

In this action, the EPA is proposing to use the conceptual approach to evaluating interstate pollution transport under CAA section 110(a)(2)(D)(i)(I) for the 2006 24-hour PM_2.5 NAAQS with respect to Idaho that the EPA explained in the 2006 24-hour PM_2.5 NAAQS Infrastructure Guidance. The EPA believes that the CAA section 110(a)(2)(D)(i)(I) SIP submission from Idaho for the 2006 24-hour PM_2.5 NAAQS may be evaluated using a “weight of the evidence” approach that takes into account available relevant information. Such information may include, but is not limited to, the amount of emissions in the state relevant to the 2006 24-hour PM_2.5 NAAQS, the meteorological conditions in the area, the distance from the state to the nearest monitors in other states that are appropriate receptors, or such other information as may be probative to consider whether sources in the state may contribute significantly to nonattainment or interfere with maintenance of the 2006 24-hour PM_2.5 NAAQS in other states. These submissions may rely on modeling when acceptable modeling technical analyses are available, but if not available, other available information can be sufficient to evaluate the presence or degree of interstate transport in a specific situation for the 2006 24-hour PM_2.5 NAAQS. For further explanation of this approach, see the technical support document (TSD) in the docket for this action.

II. State Submittal

CAA sections 110(a)(1) and (2) and section 110(l) require that revisions to a SIP be adopted by the state after reasonable notice and public hearing. The EPA has promulgated specific procedural requirements for SIP revisions in 40 CFR part 51, subpart F. These requirements include publication of notices, by prominent advertisement in the relevant geographic area, a public comment period of at least 30 days, and an opportunity for a public hearing.

On June 28, 2010, Idaho submitted a SIP to address the interstate transport requirements of CAA section 110(a)(2)(D)(i) for the 8-hour ozone and PM_2.5 NAAQS (Idaho 2010 Interstate Transport submittal).^[10] The Idaho 2010 Interstate Transport submittal included documentation of a public comment period from May 11, 2010 through June 10, 2010, and opportunity for public hearing. We find that the process followed by Idaho in adopting the SIP submittal complies with the procedural requirements for SIP revisions under CAA section 110 and the EPA's implementing regulations.

With respect to the requirement in CAA section 110(a)(2)(D)(i)(I), the Idaho 2010 Interstate Transport submittal referred to the applicable rules in the Idaho SIP, meteorological and other characteristics of areas with nonattainment problems for the 2006 24-hour PM_2.5 NAAQS in surrounding states, source apportionment data that provides information on how Idaho sources influence PM_2.5 levels at monitors in National Parks and wilderness areas surrounding Idaho. The Idaho submittal concluded that, based on the weight of the evidence, the Idaho SIP adequately addresses the interstate transport requirements of CAA section 110(a)(2)(D)(i)(I) for the 2006 24-hour PM_2.5 NAAQS. The Idaho submittal made clear that such submittal did not address the 2006 24-hour PM_2.5 nonattainment problems in the Cache Valley, a mountain valley that straddles the Utah-Idaho border. A portion of the Cache Valley has been designated nonattainment for the 2006 24-hour PM_2.5 NAAQS (Logan UT-ID nonattainment area (NAA)).^[11] Idaho stated that the State is working directly with Utah and EPA Regions 8 and 10 under a two-state, one airshed approach to address the nonattainment problems in the Logan UT-ID NAA. A detailed discussion of the Idaho 2010 Interstate Transport submittal can be found in the technical support document (TSD) in the docket for this action.

III. EPA Evaluation

To determine whether the CAA section 110(a)(2)(D)(i)(I) requirements are satisfied, the EPA must determine whether a state's emissions will contribute significantly to nonattainment or interfere with maintenance in other states. If this factual finding is in the negative, then CAA section 110(a)(2)(D)(i)(I) does not require any changes to a state's SIP. Consistent with the EPA's approach in the 1998 NO_X SIP call, the 2005 CAIR, and the 2011 Transport Rule, the EPA is evaluating these impacts with respect to specific monitors identified as having nonattainment and/or maintenance problems, which we refer to as “receptors.” See footnote 2.

With respect to this proposed action, the EPA notes that no single piece of information is by itself dispositive of the issue. Instead, the total weight of all the evidence taken together is used to evaluate significant contributions to nonattainment or interference with maintenance of the 2006 24-hour PM_2.5 NAAQS in another state. Our proposed action takes into account the Idaho 2010 Interstate Transport submittal, a supplemental evaluation of monitors in other states that are appropriate “nonattainment receptors” or “maintenance receptors,” a review of monitoring data considered representative of background, and revisions made to the Idaho SIP since the 2010 Interstate Transport submittal. In particular, we have reviewed technical information developed since the Idaho 2010 Interstate Transport submittal, specifically the Idaho SIP revision submitted in December of 2012 for purposes of addressing 24-hour PM_2.5 problems in the Logan UT-ID NAA. The EPA finalized a limited approval of portions of this December 2012 SIP submittal on March 25, 2014 (79 FR 16201).

Based on the analysis in our TSD in the docket for this action, we believe that it is reasonable to conclude that emissions from sources in Idaho do not significantly contribute to nonattainment or interfere with maintenance of the 2006 24-hour PM_2.5 NAAQS in any other state, with the following exception. We are unable to determine whether or not emissions from Idaho significantly contribute to nonattainment of the 2006 24-hour PM_2.5 NAAQS in Utah, within the Cache Valley. In the event that emissions from sources on the Idaho side of the Cache Valley do significantly contribute to nonattainment on the Utah side of the Cache Valley, we have evaluated the current Idaho SIP, and control measures in the SIP addressing emissions within the Cache Valley. We believe it is reasonable to conclude that, taking cost into account as the EPA has done in past interstate transport rulemakings, and which has been recently upheld as a valid approach by the Supreme Court (See footnote 4), Idaho has adequately addressed the interstate transport requirements of CAA section 110(a)(2)(D)(i)(I) for the 2006 24-hour PM_2.5 NAAQS. We are not, in this action, proposing to make any findings with respect to the attainment planning requirements of CAA title I, part D for the Logan UT-ID NAA. These requirements will be addressed in a separate action. Below is a summary of our evaluation. For the complete evaluation, please see the TSD in the docket for this action.

A. Identification of Nonattainment and Maintenance Receptors

The EPA evaluated data from existing monitors over three overlapping three-year periods (i.e., 2009-2011, 2010-2012, and 2011-2013) to determine which areas were violating the 2006 24-hour PM_2.5 NAAQS and which areas might have difficulty maintaining the standard. If a monitoring site measured a violation of the 2006 24-hour PM_2.5 NAAQS during the most recent three-year period (2011-2013), then this monitor location was evaluated for purposes of the significant contribution to nonattainment element of CAA section 110(a)(2)(D)(i)(I). If, on the other hand, a monitoring site showed attainment of the 2006 24-hour PM_2.5 NAAQS during the most recent three-year period (2011-2013) but a violation in at least one of the previous two three-year periods (2009-2011 or 2010-2012), then this monitor location was evaluated for purposes of the interference with maintenance element of the statute.

The State of Idaho was not covered by the modeling analyses available for the CAIR and the Transport Rule. The approach described above is similar to the approach utilized by the EPA in promulgating the CAIR and the Transport Rule. By this method, the EPA has identified those areas with monitors to be considered “nonattainment receptors” or “maintenance receptors” for evaluating whether the emissions from sources in another state could significantly contribute to nonattainment in, or interfere with maintenance in, that particular area.

B. Evaluation of Significant Contribution to Nonattainment

The EPA reviewed the Idaho 2010 Interstate Transport submittal and additional technical information to evaluate the potential for emissions from sources in Idaho to contribute significantly to nonattainment of the 2006 24-hour PM_2.5 NAAQS at specified monitoring sites in the western United States.^[12] The EPA first identified as “nonattainment receptors” all monitoring sites in the western states that had recorded PM_2.5 design values above the level of the 2006 24-hour PM_2.5 NAAQS (35 μg/m^[3] ) during the years 2011-2013.^[13] Please see the TSD in the docket for a more detailed description of the EPA's methodology for selection of nonattainment receptors. All of the nonattainment receptors we identified in western states are in California, Idaho, Montana, Oregon, and Utah.^[14]

Based on the analysis in our TSD, we believe it is reasonable to conclude that emissions from sources in Idaho do not significantly contribute to nonattainment of the 2006 24-hour PM_2.5 NAAQS in any other state, with the possible exception of Utah, within the Cache Valley. We also evaluated nonattainment receptors in eastern states, as detailed in the TSD, and we believe it is reasonable to conclude that emissions from sources in Idaho do not significantly contribute to nonattainment of the 2006 24-hour PM_2.5 NAAQS in any eastern state.

On March 25, 2014, the EPA finalized a limited approval of specific residential wood burning ordinances and road sanding agreements addressing emissions of PM_2.5 on the Idaho side of the Cache Valley (79 FR 16201). We note that because of a recent court remand of related implementing regulations,^[15] and the need to evaluate the controls for the Idaho side of the Cache Valley in conjunction with the controls submitted for the Utah side of the Cache Valley, we did not fully approve the submittal as meeting all statutory nonattainment planning requirements for the 2006 PM_2.5 NAAQS (March 25, 2014; 79 FR 16201).

However, based on the analysis in our TSD, we are proposing to determine that Idaho's SIP adequately addresses the requirements of CAA section 110(a)(2)(D)(i)(I) for the 2006 24-hour PM_2.5 NAAQS, including with respect to Utah, within the Cache Valley.

C. Evaluation of Interference With Maintenance

The EPA reviewed the Idaho 2010 Interstate Transport SIP and additional technical information to evaluate the potential for Idaho emissions to interfere with maintenance of the 2006 24-hour PM_2.5 NAAQS at specified monitoring sites in the western United States. The EPA first identified as “maintenance receptors” all monitoring sites in the western states that had recorded PM_2.5 design values above the level of the 2006 24-hour PM_2.5 NAAQS (35 μg/m³) during the 2009-2011 and/or 2010-2012 periods but below this standard during the 2011-2013 period. Please see our TSD for more information regarding the EPA's methodology for selection of maintenance receptors. All of the maintenance receptors we identified in western states are located in California, Montana, and Utah.

As detailed in the TSD, we believe it is reasonable to conclude that emissions from sources in Idaho do not interfere with maintenance of the 2006 24-hour PM_2.5 NAAQS in these states. We also evaluated maintenance receptors in eastern states, as detailed in the TSD, and we believe it is reasonable to conclude that emissions from sources in Idaho do not interfere with maintenance of the 2006 24-hour PM_2.5 NAAQS in any eastern state.

IV. Proposed Action

The EPA is proposing to find that Idaho has adequately addressed the interstate transport requirements of CAA section 110(a)(2)(D)(i)(I) for the 2006 24-hour PM_2.5 NAAQS. We are not, in this action, proposing to make any findings with respect to the attainment planning requirements of CAA title I, part D for the Logan UT-ID NAA. These requirements will be addressed in a separate action.

V. Statutory and Executive Order Reviews

Under the CAA, the Administrator is required to approve a SIP submission that complies with the provisions of the CAA and applicable Federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in reviewing SIP submissions, the EPA's role is to approve state choices, provided that they meet the criteria of the CAA. Accordingly, this action merely proposes to approve state law as meeting Federal requirements and does not impose additional requirements beyond those imposed by state law. For that reason, this action:

• Is not a “significant regulatory action” subject to review by the Office of Management and Budget under Executive Order 12866 (58 FR 51735, October 4, 1993) and 13563 (76 FR 3821, January 21, 2011);
• does not impose an information collection burden under the provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
• is certified as not having a significant economic impact on a substantial number of small entities under the Regulatory Flexibility Act (5 U.S.C. 601 et seq.);
• does not contain any unfunded mandate or significantly or uniquely affect small governments, as described in the Unfunded Mandates Reform Act of 1995 (Pub. L. 104-4);
• does not have Federalism implications as specified in Executive Order 13132 (64 FR 43255, August 10, 1999);
• is not an economically significant regulatory action based on health or safety risks subject to Executive Order 13045 (62 FR 19885, April 23, 1997);
• is not a significant regulatory action subject to Executive Order 13211 (66 FR 28355, May 22, 2001);
• is not subject to requirements of Section 12(d) of the National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 note) because it does not involve technical standards; and
• does not provide the 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, the SIP is not approved to apply on any Indian reservation land or in any other area where the EPA or an Indian tribe has demonstrated that a tribe has jurisdiction. In those areas of Indian country, the rule does not have tribal implications as specified by Executive Order 13175 (65 FR 67249, November 9, 2000), nor will it impose substantial direct costs on tribal governments or preempt tribal law.

List of Subjects in 40 CFR Part 52

• Environmental protection
• Air pollution control
• Incorporation by reference
• Intergovernmental relations
• Particulate matter
• Reporting and recordkeeping requirements

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

Dated: February 5, 2015.

Dennis J. McLerran,

Regional Administrator, Region 10.

Footnotes

1.  This proposed action does not address the two elements of the interstate transport SIP provision in CAA section 110(a)(2)(D)(i)(II) regarding interference with measures required to prevent significant deterioration of air quality or to protect visibility in another state. We previously approved the Idaho SIP for purposes of CAA section 110(a)(2)(D)(I)(II) for the 2006 24-hour PM_2.5 NAAQS on July 14, 2014 (79 FR 40662).

2.  See NO_X SIP Call, 63 FR 57371 (October 27, 1998); Clean Air Interstate Rule (CAIR), 70 FR 25172 (May 12, 2005); and Transport Rule or Cross-State Air Pollution Rule, 76 FR 48208 (August 8, 2011).

3.  CAIR addressed the 1997 annual and 24-hour PM_2.5 NAAQS, and the 1997 8-hour ozone NAAQS. It did not address the 2006 24-hour PM_2.5 NAAQS. For more information on CAIR, please see our July 30, 2012 proposal for Arizona regarding interstate transport for the 2006 PM_2.5 NAAQS (77 FR 44551, 44552).

4.  EPA v. EME Homer City Generation, L.P., 134 S.Ct. 1584 (2014).

5.  USCA Case #11-1302, Document #1518738, Filed 10/23/2014.

6.  Transport Rule or Cross-State Air Pollution Rule, 76 FR 48208 (August 8, 2011).

7.  See Memorandum from William T. Harnett entitled “Guidance on SIP Elements Required Under Sections 110(a)(1) and (2) for the 2006 24-Hour Fine Particle (PM_2.5) National Ambient Air Quality Standards (NAAQS),” September 25, 2009, available at http://www.epa.gov/​ttn/​caaa/​t1/​memoranda/​20090925_​harnett_​pm25_​sip_​110a12.pdf.

8.  See Memorandum from William T. Harnett entitled “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_2.5 National Ambient Air Quality Standards,” August 15, 2006, available at http://www.epa.gov/​ttn/​caaa/​t1/​memoranda/​section110a2di_​sip_​guidance.pdf.

9.  The 2006 24-hour PM_2.5 NAAQS Infrastructure Guidance stated that EPA was working on a new rule to replace CAIR that would address issues raised by the Court in the North Carolina case and that would provide guidance to states in addressing the requirements related to interstate transport in CAA section 110(a)(2)(D)(i)(I) for the 2006 24-hour PM_2.5 NAAQS. It also noted that states could not rely on the CAIR rule for section 110(a)(2)(D)(i)(I) submissions for the 2006 24-hour PM_2.5 NAAQS because the CAIR rule did not address this NAAQS. See 2006 PM_2.5 NAAQS Infrastructure Guidance at 4.

10.  The Idaho 2010 Interstate Transport submittal addressed the interstate transport requirements of the 1997 PM_2.5, 1997 ozone, 2006 PM_2.5, and 2008 ozone NAAQS. In this action, we are only taking action with respect to CAA section 110(a)(2)(D)(i)(I) for the 2006 24-hour PM_2.5 NAAQS. The EPA has addressed CAA section 110(a)(2)(D)(i)(II) for the 2006 PM_2.5 and 2008 ozone NAAQS in a separate action (July 14, 2014, 79 FR 40662). In addition, we previously approved the Idaho SIP for 110(a)(2)(D)(i) with respect to the 1997 PM_2.5 and 1997 ozone NAAQS on November 26, 2010 (75 FR 72705). Finally, we will address the requirements of CAA section 110(a)(2)(D)(i)(I) with respect to the 2008 ozone NAAQS in a future action.

11.  The EPA designated areas nonattainment for the 2006 24-hour PM_2.5 NAAQS on November 13, 2009, including the Logan UT-ID nonattainment area, commonly referred to as the Cache Valley nonattainment area (74 FR 58688).

12.  The EPA has also considered potential PM_2.5 transport from Idaho to the nearest nonattainment and maintenance receptors located in the eastern, midwestern, and southern states covered by the Transport Rule and believes it is reasonable to conclude that, given the significant distance from Idaho to the nearest such receptor (in Illinois) and the relatively insignificant amount of emissions from Idaho that could potentially be transported such a distance, emissions from Idaho sources do not significantly contribute to nonattainment or interfere with maintenance of the 2006 24-hour PM_2.5 NAAQS at this location. These same factors also support a finding that emissions from Idaho sources neither contribute significantly to nonattainment nor interfere with maintenance of the 2006 24-hour PM_2.5 NAAQS at any location further east. See TSD at Section II.C.

13.  Because CAIR did not cover states in the western United States, these data are not significantly impacted by the remanded CAIR at the time and thus could be considered in this analysis.

14.  As this analysis is focused on interstate transport, the EPA did not evaluate the impact of Idaho emissions on nonattainment receptors within Idaho.

15.  On January 4, 2013, the U.S. Court of Appeals in the District of Columbia, in Natural Resources Defense Council v. EPA, 706 F.3d 428 (D.C. Cir.), issued a judgment that remanded two of the EPA's rules implementing the 1997 PM_2.5 NAAQS, including the “Implementation of New Source Review (NSR) Program for Particulate Matter Less Than 2.5 Micrometers (PM_2.5),” (73 FR 28321, May 16, 2008) (2008 PM_2.5 NSR Implementation Rule). The Court ordered the EPA to “repromulgate these rules pursuant to Subpart 4 consistent with this opinion.” Id. at 437. Subpart 4 of Part D, Title 1 of the CAA establishes additional provisions for particulate matter nonattainment areas. On June 2, 2014, the EPA repromulgated these rules pursuant to Subpart 4 (79 FR 31566).