2024-16502. Air Plan Approval; IA; Regional Haze State Implementation Plan for the Second Implementation Period

Table 1—Summary of Modeled Contributions on 20% Most Impaired Days From LADCO's 2028 CAM x PSAT Analysis and Determination of Class I Areas Linked to Iowa's Emissions in 2nd Planning Period

State	Class I area	Total modeled extinction excluding Rayleigh & Sea Salt (Mm −1 )	Iowa's modeled anthropogenic contributions *		Class I areas linked to Iowa's emissions in 2nd planning period
			Mm −1	%
Arkansas	Caney Creek	42.95	0.59	1.4
Arkansas	Upper Buffalo	42.96	0.90	2.1
Kentucky	Mammoth Cave	62.89	1.81	2.9
Michigan	Isle Royale	36.36	1.42	3.9	X
Michigan	Seney	45.12	1.49	3.3	X
Minnesota	Boundary Waters	29.31	0.94	3.2	X
Minnesota	Voyageurs	28.74	0.87	3.0	X
Missouri	Hercules-Glades	48.13	1.86	3.9	X
Missouri	Mingo	57.35	1.34	2.3
Oklahoma	Wichita Mountains	44.82	0.56	1.2
South Dakota	Badlands	22.47	0.25	1.1
South Dakota	Wind Cave	18.10	0.18	1.0
* The anthropogenic contributions account for sulfates, nitrates, and primary particulates.

We acknowledge that the 3 percent or greater State contribution threshold used to determine whether Iowa emissions contribute to visibility impairment at a particular Class I area may be higher than what EPA believes is an “extremely low triggering threshold” intended by the statute and regulations. However, we note that although Iowa did not establish formal linkages to Class I areas other than Isle Royale, Seney, Boundary Waters, Voyageurs, and Hercules-Glades, the State evaluated source impacts on all twelve of the Class I areas listed in table 1 in the source-selection process as discussed in section V.E.a. of this document. Furthermore, Iowa consulted with other states and FLMs regarding their long-term strategy for regional haze through regional calls organized by CenSARA and LADCO. At the time of submission, no other states requested additional emission reduction measures or evaluation of other Class I areas. As discussed in further detail below, the EPA is proposing to find that Iowa has submitted a regional haze plan that meets the requirements of 40 CFR 51.308(f)(2) related to the development of a long-term strategy. Thus, although the 3 percent contribution threshold used in this analysis may be higher than intended by the statute and regulation, we propose to find that Iowa appropriately evaluated its visibility impact at twelve out of State Class I areas and has satisfied the applicable requirements for making reasonable progress towards natural visibility conditions in Class I areas that may be affected be emissions from the State.

D. Calculations of Baseline, Current, and Natural Visibility Conditions; Progress to Date; and the Uniform Rate of Progress

Section 51.308(f)(1) requires states to determine the following for “each mandatory Class I Federal area located within the State”: baseline visibility conditions for the most impaired and clearest days, natural visibility conditions for the most impaired and clearest days, progress to date for the most impaired and clearest days, the differences between current visibility conditions and natural visibility conditions, and the URP. This section also provides the option for states to propose adjustments to the URP line for a Class I area to account for visibility impacts from anthropogenic sources outside the United States and/or the impacts from wildland prescribed fires that were conducted for certain, specified objectives. 40 CFR 51.308(f)(1)(vi)(B).

These requirements only apply to states with Class I areas. These statutory requirements do not apply because Iowa does not have any Class I areas.

E. Long-Term Strategy for Regional Haze

a. Iowa's Source Selection and Four Factor Analysis

Each state having a Class I area within its borders or emissions that may affect visibility in a Class I area must develop a long-term strategy for making reasonable progress towards the national visibility goal. CAA section 169A(b)(2)(B). As explained in the Background section of this document, reasonable progress is achieved when all states contributing to visibility impairment in a Class I area are implementing the measures determined—through application of the four statutory factors to sources of visibility impairing pollutants—to be necessary to make reasonable progress. 40 CFR 51.308(f)(2)(i). Each state's long-term strategy must include the enforceable emission limitations, compliance schedules, and other measures that are necessary to make reasonable progress. 40 CFR 51.308(f)(2). All new ( i.e., additional) measures that are the outcome of four-factor analyses are necessary to make reasonable progress and must be in the long-term strategy. If the outcome of a four-factor analysis and other measures necessary to make reasonable progress is that no new measures are reasonable for a source, that source's existing measures are necessary to make reasonable progress, unless the state can demonstrate that the source will continue to implement those measures and will not increase its emission rate. Existing measures that are necessary to make reasonable progress must also be in the long-term strategy. In developing its long-term strategies, a state must also consider the five additional factors in § 51.308(f)(2)(iv). As part of its reasonable progress determinations, the state must describe the criteria used to determine which sources or group of sources were evaluated ( i.e., subjected to four-factor analysis) for the second implementation period and how the four factors were taken into consideration in selecting the emission reduction measures for inclusion in the long-term strategy. 40 CFR 51.308(f)(2)(iii).

The following paragraphs summarize how Iowa's SIP submission addressed the requirements of § 51.308(f)(2)(i). The EPA's evaluation of Iowa's SIP revision with regard to the same is contained in the following section V.E.b. and in the technical support document (TSD) in the docket for this action.

States may rely on technical information developed by the RPOs of which they are members to select sources for four-factor analysis and to conduct that analysis, as well as to satisfy the documentation requirements under § 51.308(f). Where an RPO has performed source selection and/or four-factor analyses (or considered the five additional factors in § 51.308(f)(2)(iv)) for its member states, those states may rely on the RPO's analyses for the purpose of satisfying the requirements of § 51.308(f)(2)(i) so long as the states have a reasonable basis to do so and all state participants in the RPO process have approved the technical analyses. 40 CFR 51.308(f)(2)(iii). States may also satisfy the requirement of § 51.308(f)(2)(ii) to engage in interstate consultation with other states that have emissions that are reasonably anticipated to contribute to visibility impairment in a given Class I area under the auspices of intra- and inter-RPO engagement.

Iowa is a member of the CenSARA RPO. CenSARA and its contractor provided member States with an area of influence (AOI) study for Class I areas throughout and near the CenSARA region. The AOI study provided by CenSARA is a technical analysis product to help assess source and State-level contributions to visibility impairment and the need for interstate consultation. Iowa relied upon the AOI study to conduct an analysis of emission sources and select sources for a four-factor analysis.

The cumulative sulfate and nitrate extinction weighted residence time (EWRT) multiplied by Q/d (emissions divided by distance) analysis was performed by a CenSARA contractor using 2016 actual emissions data and 2028 emissions projections. It relied on a back-trajectory model combined with air quality measurement data and emission inventories to identify the geographic areas and emission sources with a high probability of contributing to anthropogenically impaired visibility at Class I areas within CenSARA and nearby states. For the EWRT multiplied by Q/d analysis, back trajectory residence times were first calculated by summing the amount of time trajectories reside in a specific geographic area ( e.g., modeling grid cell). The trajectory residence times were then weighted by sulfate and nitrate extinction coefficients to account for the varying contributions of sulfates and nitrates to total light extinction. To determine the potential impact from sources of SO₂ and NO_X emissions (precursors of SO₄ and NO₃, respectively), the EWRT values for SO₄ and NO₃ were combined with emissions ( Q ) from sources of SO₂ and NO_X, respectively. CenSARA States chose to focus on electric generating units (EGU) and non-EGU point sources since these sources comprise major fractions of the NO_X and SO₂ emissions inventory. To incorporate the effects of dispersion, deposition, and chemical transformation along the path of the trajectories, emissions were inversely weighted by the distance ( d) between the centers of the grid cell emitting the emissions and the grid cell containing the IMPROVE site. The AOI study and analysis tool are included in appendix B and appendix C-1 of the State submission.

For its own analysis, IDNR decided to sum the sulfate and nitrate contributions for each facility based on 2016 emissions. Rather than evaluating all sources with an individual impact greater than a given percentage, such as 1 percent, Iowa used the per-facility percentage contributions (ranked from largest to smallest) for Iowa facilities, as well as sources in other states, to compute a cumulative (rolling total) percentage of the total visibility impairment for a Class I area. The cumulative rankings for each of the 12 Class I areas evaluated by IDNR is provided in appendix C-2 of the State submission.

Based on that analysis, Iowa decided to select sources for a four-factor analysis based upon a cumulative percentage threshold of 50 percent, or all sources contributing to a majority of the combined (sulfate plus nitrate) impacts in any Class I area. This approach of focusing on cumulative sulfate and nitrate impacts among all sources at each Class I area resulted in the selection of sources with fairly low individual contributions to those Class I areas. This analysis resulted in Iowa selecting two sources for four-factor analysis: Louisa Generating Station (LGS) and Walter Scott Jr. Energy Center (WSEC). The LGS and WSEC each contributed to a majority of the combined visibility impacts at Isle Royale, even though their individual sulfate plus nitrate impacts were 0.86% and 0.55%, respectively. No other Iowa source contributed above the 50 percent threshold chosen by IDNR in any other Class I area.

To support the development of emissions reduction measures, Iowa gathered information on each of the four statutory factors for the two sources identified. Both sources are coal-fired EGUs operated by MidAmerican Energy Company. Source-specific data included explanations of source characteristics, existing controls for SO₂ and NO_X, unit-level emissions, projected boiler operations, and the identification of technically feasible control options for SO₂ and NO_X. In section 5 of Iowa's submittal, the State explains the four-factor analyses performed by the MidAmerican Energy Company for the two facilities. The analyses evaluated the costs of control options, potential time frames for compliance with control options, potential energy, and non-air quality environmental impacts of certain control options, and how the remaining useful lives of sources might be considered in a control analysis. The state also considered the visibility impacts of control options as an additional factor. Iowa's emission reduction measures were based on these analyses and looked to either optimize the use of existing controls or require the addition of new controls.

LGS has one boiler that is currently equipped with dry lime flue gas desulfurization (FGD) system to reduce SO₂ emissions and low NO_X burners (LNB) with overfire air (OFA) to reduce NO_X emissions. WSEC has two boilers, identified as Unit 3 (WSEC-3) and Unit 4 (WSEC-4). Both units are equipped with dry lime FGD to reduce SO₂ emissions and LNB with OFA to reduce NO_X . Unit 4 additionally includes a selective catalytic reduction (SCR) system to further control NO_X emissions. Based on the analysis of technically feasible control options, Iowa determined that WSEC-4 is currently equipped with all feasible control options.

Four potential control options were identified for LGS and WSEC-3. The two evaluated SO₂ controls were operational improvements to the existing dry FGD systems or replacement with new wet FGDs. The two evaluated NO_X controls included the addition of either selective noncatalytic reduction (SNCR) or SCR systems.

The source evaluated the cost of each identified control option for LGC and WSEC. The results for the SO₂ control options are shown in table 2 and the results of the NO_X control options are shown in table 3. The full cost control analysis was provided in appendix D-1 of the State submission and is included in the docket for this action.

Table 2—Cost of Evaluated SO ₂ Control Options

Facility	Control technology	Total annualized cost ($)	Emission reduction (tons/year)	Effective cost ($/ton)
LGS (Unit 101)	Improve Existing Dry FGD	$1,102,000	3,903	$282
	Wet FGD	42,122,000	4,722	8,920
WSEC-3	Improve Existing Dry FGD	1,248,000	5,785	216
	Wet FGD	41,163,000	6,687	6,160

Table 3—Cost of Evaluated NO _X Control Options

Facility	Control technology	Total annualized cost ($)	Emission reduction (tons/year)	Effective cost ($/ton)
LGS (Unit 101)	SNCR	$3,621,000	566	$6,398
	SCR	24,271,942	2,739	8,862
WSEC-3	SNCR	4,240,300	755	5,616
	SCR	24,771,688	3,849	6,436

MidAmerican evaluated the time necessary for compliance for each potential control option for the two sources. MidAmerican estimated that improvements to the existing dry FGD systems at both LGC and WSEC-3 could be implemented within approximately six months. The company estimated that the time needed to install and implement new wet FGD systems would be approximately five years. The company estimated SNCR could be implemented within three years and SCR could be implemented within five years. Iowa determined these timeframes were appropriate for considering the time necessary for compliance, but this factor was not used to eliminate any potential control options.

In the State submission, Iowa characterized the information provided by MidAmerican on the statutory factors of energy and non-air quality environmental impacts and the remaining useful life of the sources consistent with 2019 Guidance. MidAmerican evaluated energy and non-air quality environmental impacts for each technically feasible control option but this factor was not used to eliminate any potential control options. The remaining useful life of the two sources was also evaluated but was not a determining factor in selecting control measures because operation of these units is not limited. In completing the control cost analysis, the company considered the useful life of the control systems.

Iowa also evaluated the visibility impacts of control measures as a fifth factor and presented this analysis in section 5.8 of the State's submission. As explained in section IV.C. of this proposed rule, states have flexibility under the CAA and RHR to reasonably consider visibility benefits as an optional additional factor alongside the four statutory factors. The 2019 Guidance and the 2021 Clarification Memo provide recommendations and guidance on how states can consider modeled visibility impacts or benefits in the context of a four-factor analysis. For its analysis, Iowa calculated a ratio of sulfate impacts relative to nitrate impacts from LGS and WSEC on the 20% most impaired days at the five linked Class I areas. Iowa first quantified the State's predicted anthropogenic sulfate and nitrate contributions to the 20% most impaired days at each of the Class I areas based on LADCO's 2028 CAMx PSAT modeling results. The results are presented as extinction values in Mm-1 and percent of total modeled visibility impairment in tables 5-7 and 5-8 of the State's submission. Iowa then chose the maximum predicted sulfate and nitrate contributions attributed to the State's anthropogenic emissions among the five linked Class I areas (Isle Royale, Seney, Boundary Waters, Voyageurs, and Hercules-Glades). The maximum sulfate impact is 1.000 Mm-1 at Hercules-Glades, and the maximum nitrate impact is 0.798 Mm-1 at Seney. The maximum sulfate and nitrate extinction values were then apportioned to LGS and WSEC based on the 2028 projected anthropogenic emissions inventory for Iowa, which is summarized in table 5-9 and Figure 5-4 of the State's submission. EGUs are projected to emit 78.8% and 22.2% of Iowa's 2028 SO₂ and NO_X emissions, respectively.^[34] To calculate factors for apportioning sulfate and nitrate contributions to LGS and WSEC, Iowa assumed that LGS and WSEC emit the entirety of the State's projected 2028 EGU SO₂ and NO_X emissions totals. For each pollutant, the percentage of statewide EGU emissions was multiplied by the ratio of each facility's emissions to the sum of LGS and WSEC emissions.^[35] The resulting factors were then multiplied by the statewide maximum sulfate and nitrate impact values. LGS's estimated sulfate contribution is 0.285 Mm-1 and its nitrate contribution is 0.064 Mm-1. The corresponding sulfate and nitrate impacts for WSEC are 0.503 Mm-1 and 0.133 Mm-1, respectively. For both LGS and WSEC, Iowa's analysis indicates that sulfate impacts are estimated to be 4.4 times the nitrate impacts. Table 4 summarizes Iowa's calculations and the resulting estimated sulfate and nitrate impacts from LGS and WSEC.

Table 4—Estimated Sulfate and Nitrate Impacts Attributed to LGS and WSEC on the 20% Most Impaired Days at Iowa's Five Linked Class I Areas

Facility	2028 Projected emissions		Apportionment factor		Sulfate impact (Mm-1)	Nitrate impact (Mm-1)	Ratio (sulfate/ nitrate impact)
	SO 2 (tpy)	NO X (tpy)	SO 2 (%)	NO X (%)
LGS	5,605	3,403	28.5	8.0	0.285	0.064	4.4
WSEC	9,897	6,025	50.3	14.2	0.503	0.113	4.4

Based upon the four-factor analysis for LGS and WSEC, Iowa determined that implementing operational improvements to the existing dry FGD systems at LGS and WSEC-3 were necessary to make reasonable progress. The cost effectiveness of this control option at LGS is less than $300 per ton and results in an estimated reduction of actual SO₂ emissions by 3,903 tons per year from this source. The cost effectiveness of this control option at WSEC is less than $300 per ton and results in an estimated reduction of actual SO₂ emissions by 5,785 tons per year from this source. The state determined the new wet FGD systems were not considered reasonable due to the cost and estimated incremental decrease in SO₂ emissions being relatively small compared to improvements to the existing dry FGD systems (less than 14 percent versus baseline emissions at LGS and less than 11 percent versus baseline emissions at WSEC-3).^[36] Iowa decided not to require the addition of SNCR or SCR control systems to further control NO_X emissions at either facility at this time due to the estimated cost effectiveness of both options exceeding $5,000 per ton and the lower visibility benefits than compared to SO₂ controls.

Based on the conclusions from the four-factor analysis, Iowa modified the air construction permits for the main boiler at LGS and WSEC-3 to implement operational improvements to the existing dry FGD systems. The permits include new SO₂ emissions limits and compliance schedules. The new SO₂ emission limit for the main boiler at LGS is 800 lb/hr based on a 30-day rolling average. The new SO₂ emission limit for WSEC-3 is 770 lb/hr based on a 30-day rolling average. Iowa issued both permits on July 20, 2023, with compliance dates of December 31, 2023. Iowa determined that WSEC-4 is currently equipped with all feasible control options. The current permit restricts WSEC-4 to an enforceable best available control technology (BACT) SO₂ emission limit of 0.1 lb/MMBtu and a NO_X emission limit of 0.07 lb/MMBtu. To establish permanent emission limits for its long-term strategy for regional haze, Iowa submitted the air construction permits for LGS, WSEC-3, and WSEC-4 for incorporation into the SIP in 40 CFR 52.820(d), EPA approved state source-specific requirements. The State's SIP submission requested that the EPA not act on Condition 11 of the permits for LGS and WSEC-3 nor Condition 6 of the permit for WSEC-4, and accordingly those conditions are not included in this action. The full permits are included in appendix E of the State submission in the docket for this action.

b. The EPA's Evaluation of Iowa's Emissions Reduction Measures and Compliance With § 51.308(f)(2)(i)

The EPA is proposing to find that Iowa has satisfied the requirements of § 51.308(f)(2)(i) related to evaluating sources and determining the emission reduction measures that are necessary to make reasonable progress by considering the four statutory factors. We are proposing to find that Iowa reasonably evaluated the two pollutants—SO₂ and NO_X —that currently drive visibility impairment within the linked Class I areas and that it adequately explained and supported its decision to focus on these two pollutants through its technical analyses included in the state submission.^[37]

Section 51.308(f)(2)(i) requires states to evaluate and determine the emission reduction measures that are necessary to make reasonable progress by applying the four statutory factors to sources in a control analysis. The State must include in its implementation plan a description of the criteria it used to determine which sources or groups of sources it evaluated and how the four factors were taken into consideration in selecting the measures for inclusion in its long-term strategy. As explained above, Iowa relied on the cumulative sulfate and nitrate emissions weighted residence time (EWRT) multiplied by Q/d (emissions divided by distance) analysis performed by a CenSARA contractor to compute a cumulative percentage of the total visibility impairment from major sources for each Class I area. Iowa used the per-facility percentage contributions (ranked from largest to smallest) to compute a cumulative (rolling total) percentage of the total visibility impairment to each Class I area. Iowa selected sources for four-factor analysis based upon a cumulative impact threshold of 50 percent in any Class I area. Based on this analysis, Iowa selected two sources: Louisa Generating Station and Walter Scott Jr. Generating Station.

Pursuant to the RHR, states must consider selecting sources identified by other states or by FLMs. A state receiving a request to select a particular source(s) should either perform a four-factor analysis on the source(s) or provide a well-reasoned explanation as to why it is choosing not to do so. See 2021 Clarifications Memo at 4. No other states identified additional sources for evaluation. During initial consultations with FLMs, Iowa received recommendations from FLMs to evaluate several sources. The U.S. Forest Service identified three sources based on its review of emission rate data (lb/MMBtu) and results from a LADCO Q/d analysis: University of Northern Iowa, Burlington Generating Station, and Muscatine Power and Water, Unit 8. The National Park Service identified eleven Iowa sources using a Q/d(SO₂ + NO_X) threshold of 1.2 based on 2017 National Emissions Inventory (NEI) emissions data for the non-EGUs and 2019 Clean Air Markets Division (CAMD) data for EGUs: Walter Scott Jr. Energy Center (EGU), Louisa Generating Station (EGU), George Neal North (EGU), George Neal South (EGU), Burlington Generating Station (EGU), Muscatine Power and Water (EGU), Ottumwa Generating Station (EGU), ADM Corn Processing—Cedar Rapids (non-EGU), Continental Cement Company—Davenport (non-EGU), Natural Gas Pipeline Co. Of America—Station 107 (non-EGU), and Northern Natural Gas Co.—Ogden (non-EGU). However, Iowa chose to rely on a different source selection methodology based on CenSARA's AOI analysis, as explained above and in the State submission. While Iowa did not select additional sources identified by FLMs for four-factor analysis, it provided supplemental information supporting its decision to use CenSARA's AOI analysis because it resulted in more technical data.

During the formal FLM consultation and public comment period, Iowa received several comments to broaden its source selection criteria by using a higher percent contribution threshold and expand its source selection to include two additional sources in Iowa: George Neal North and George Neal South. As explained in the 2021 Clarifications Memo, states have the discretion to choose any source selection threshold or methodology that is reasonable, as long as whatever choices states make are reasonably explained and produce a reasonable outcome. 2021 Memo at 3. Iowa described its source selection criteria in the state submission and selected all sources that met the source selection threshold. In this case, the 50 percent cumulative impact threshold identified two sources in Iowa. We note that Iowa selected its two largest EGUs for four-factor analysis and that the evaluation of these sources had the potential to meaningfully reduce their contributions to visibility impairment. Furthermore, the 2019 Guidance explains that the Regional Haze Rule “sets up an iterative planning process and anticipates that a state may not need to analyze control measures for all its sources in a given SIP revision.” 2019 Guidance at 9. Thus, although the source selection threshold resulted in two sources being evaluated, Iowa reasonably chose factors to consider when selecting sources and applied these factors in a reasonable way. Therefore, we propose to find Iowa's source selection methodology and the sources selected for further analysis to be reasonable for the second planning period.

As detailed above, Iowa included four-factor analyses performed by MidAmerican Energy Company for each of the two sources selected for further analysis. The state chose to evaluate visibility benefits of control measures along with the four statutory factors and described how each of the factors were considered in the SIP submission. In considering whether compliance costs for sources were reasonable, Iowa evaluated the cost estimates for each technically feasible control option for both SO₂ and NO_X completed by MidAmerican.

Based on the EPA's review, we find that Iowa's control cost analysis was both reasonable and consistent with the EPA Air Pollution Control Cost Manual.^[38] The State submission included details on the consideration of the time necessary for compliance, the energy and non-air quality environmental impacts of compliance, and the remaining useful life of any potentially affected sources. EPA finds the consideration of these statutory factors was reasonable and consistent with the 2019 Guidance and 2021 Clarifications Memo. The EPA further reviews the control cost analyses in the TSD contained in the docket for this rulemaking.

Iowa also included a visibility benefits analysis that estimated sulfate impacts relative to nitrate impacts from LGS and WSEC on the 20% most impaired days at the five linked Class I areas, as described in section V.E.a. of this document. Based on that analysis, the State estimated that sulfate impacts to visibility in the linked Class I areas are 4.4 times greater than nitrate impacts for both LGS and WSEC. While visibility is not an explicitly listed factor to consider when determining whether additional controls are reasonable, the purpose of the four-factor analysis is to determine what degree of progress toward natural visibility conditions is reasonable. Therefore, the EPA has interpreted the CAA and the RHR as allowing states to consider visibility alongside the four statutory factors when comparing multiple emission reduction control options that may be necessary to make reasonable progress. See 2021 Clarifications Memo at 12. We find that Iowa's consideration of visibility improvements was reasonable and consistent with the requirements of the CAA.

The State determined that operational improvements to the existing FGD systems at both LGS and WSEC-3 were the most cost-effective control option and showed reducing SO₂ emissions increased visibility benefits in several Class I areas. Iowa stated that these emission reduction measures will reduce actual SO₂ emissions by an estimated 9,688 tons per year. The State determined that WSEC-4 is currently equipped with all feasible control options and that the existing measures are necessary to reasonable progress. Iowa submitted the air construction permits for LGS, WSEC-3, and WSEC-4 for inclusion in its long-term strategy. The permits are included in appendix E of the State submission in the docket for this action. Section 51.308(f)(2) of the RHR requires that emission reduction measures must be represented by “enforceable emissions limitations, compliance schedules, and other measures” ( i.e., any additional compliance tools) in a state's long-term strategy in its SIP. 40 CFR 51.308(f)(2). The permits for LGS and WSEC-3 include limits in lb/hour, with compliance determined on thirty-day rolling averages through the use of Continuous Emission Monitors (CEMs) to the EPA standards, necessary recordkeeping and reporting requirements, and cover all times of operation. The new limits are: 800 lb/hr for MidAmerican Energy Co.—Louisa Station Unit EU1, Louisa Boiler, and 770 lb/hr for MidAmerican Energy Co.—Walter Scott Jr. Energy Center, Unit 003, Boiler #3. WSEC-4 was subject to the prevention of significant deterioration (PSD) preconstruction permitting for SO₂ and NO_X emissions in 2003. As part of the PSD review process, BACT was required for SO₂ and NO_X controls. The air construction permit includes a BACT SO₂ emission limit of 0.1 lb/MMBtu (30-day rolling average) and an annual emission restriction of 3,362 tons per rolling 12-month period. The BACT emission limit for NO_X is 0.07 lb/MMBtu (30-day rolling average) and an annual emission restriction of 2,353 tons per rolling 12-month period. Compliance with SO₂ and NO_X BACT limits is demonstrated using continuous emissions monitoring systems (CEMS). The EPA finds the air quality construction permits, submitted by Iowa to serve as the enforceable mechanism of the long-term strategy, meet the requirements of § 51.308(f)(2) to include enforceable emissions limitations. We propose to find Iowa's four-factor analysis and emission reduction measures to be reasonable for the second planning period.

In sum, the EPA proposes to find that Iowa has satisfied the requirements that states determine the emission reduction measures that are necessary to make reasonable progress by considering the four factors, and that its long-term strategy includes the enforceable emission limitations, compliance schedules, and other measures necessary to make reasonable progress.

c. Additional Long-Term Strategy Requirements

The consultation requirements of § 51.308(f)(2)(ii) provides that states must consult with other states that are reasonably anticipated to contribute to visibility impairment in a Class I area to develop coordinate emission management strategies containing the emission reductions measures that are necessary to make reasonable progress. Section 51.308(f)(2)(ii)(A) and (B) require states to consider the emission reduction measures identified by other states as necessary for reasonable progress and to include agreed upon measures in their SIPs, respectively. Section 51.308(f)(2)(ii)(C) speaks to what happens if states cannot agree on what measures are necessary to make reasonable progress.

Iowa included documentation of its consultation with RPOs and individual states in its SIP submission. Specifically, Iowa consulted with three states containing the five Class I Areas that Iowa sources were expected to impact: Minnesota, Michigan, and Missouri. Documentation of consultation with each state is contained in appendix H to the State submittal. In addition, Iowa consulted with CenSARA and LADCO through its participation in regular planning calls each RPO. Iowa did not receive any requests from other states nor did it encounter any disagreements. We propose to determine that Iowa has satisfied the consultation requirements of § 51.308(f)(2)(ii).

The documentation requirement of § 51.308(f)(2)(iii) provides that states may meet their obligations to document the technical bases on which they are relying to determine the emission reductions measures that are necessary to make reasonable progress through an RPO, as long as the process has been “approved by all State participants.”

Section 51.308(f)(2)(iii) also requires that the emissions information considered to determine the measures that are necessary to make reasonable progress include information on emissions for the most recent year for which the state has submitted triennial emissions data to the EPA (or a more recent year), with a 12-month exemption period for newly submitted data. Iowa's SIP submission included in section 7 emissions information by sector and pollutant from LADCO's 2016 modeling inventory and from the 2017 NEI. The state analysis included data from the 2016 base year and 2028 modeled emissions inventories for NO_X, SO₂, PM_2.5, VOCs, and NH₃. The State's four factor analysis relied on emission data from 2009-2021. The State also included emission data from 2009-2021 for Iowa EGUs. Based on Iowa's consideration of the emission data in their SIP submittal, the EPA proposes to find that Iowa has satisfied the emissions information requirement in § 51.308(f)(2)(iii).

We also propose to find that Iowa reasonably considered the five additional factors in § 51.308(f)(2)(iv) in developing its long-term strategy. Pursuant to § 51.308(f)(2)(iv)(A), Iowa noted that existing and ongoing state and Federal emission control programs that contribute to emission reductions through 2028 would impact emissions of visibility impairing pollutants from point and nonpoint sources in the second implementation period. Iowa included in its SIP submission details of control measures with their effective dates and pollutants addressed.

Iowa's consideration of measures to mitigate the impacts of construction activities as required by § 51.308(f)(2)(iv)(B) is included in section 6.2.2. of its SIP submission. Iowa described the minor NSR permit requirements for aggregate processing plants, concrete batch plants, and asphalt plants and its rules to reduce fugitive dust emissions from beyond the property line.^[39] Iowa noted that construction activities are unlikely to contribute to visibility impairment in Class I areas due to the extensive transport distances in combination with relatively low emissions and release heights for construction activities.

Pursuant to § 51.308(f)(2)(iv)(C), source retirements and replacement schedules are addressed in section 6.2.3 of Iowa's submission. The LADCO modeling used by Iowa considered known source retirements and replacements in developing the 2028 emission projections. The Iowa EGU source retirements, refuelings, or replacements that occurred during or after the 2016 base year are identified in table 6-4 of the State submission.^[40]

Iowa's consideration of smoke management as required in 40 CFR 51.308(f)(2)(iv)(D) is included in section 6.2.4. of the SIP submission. Iowa explained that source apportionment modeling conducted by Central Regional Air Planning Association (CENRAP) for the first implementation period demonstrated that fires in Iowa do not significantly contribute to visibility in Class I areas. Iowa determined that conclusion is still valid since Iowa's total prescribed fire and agricultural fire emissions represent less than one percent of the U.S. totals in the 2017 NEI, as shown in tables 6-5 and 6-6 of the State submission.

Iowa considered the anticipated net effect of projected changes in emissions as required by § 51.308(f)(2)(iv)(E) by discussing, in section 8 of its submission, the photochemical modeling for the 2018-2028 period it conducted by LADCO. Table 8-1 of the State submission summarizes the visibility improvements in linked Class I areas. The results show improvements of 0.71 to 1.24 deciviews on the 20 percent most impaired days and no visibility degredation on the clearest days. Iowa explained the results are conservative because they do not incorporate the scrubber improvements from its long term strategy (LTS), which will further improve visibility.

Because Iowa has reasonably considered each of the five additional factors the EPA proposes to find that Iowa has satisfied the requirements of 40 CFR 51.308(f)(2)(iv).

F. Reasonable Progress Goals

Section 51.308(f)(3) contains the requirements pertaining to RPGs for each Class I area. This provision does not apply to Iowa because it does not have a Class I Area. Section 51.308(f)(3)(ii)(B) requires that if a state contains sources that are reasonably anticipated to contribute to visibility impairment in a Class I area in another state, and the RPG for the most impaired days in that Class I area is above the URP, the upwind state must provide the same demonstration. This provision does not apply because the states with Class I areas that are affected by Iowa sources did not submit any RPGs that are above the URP.

G. Monitoring Strategy and Other Implementation Plan Requirements

Section 51.308(f)(6) specifies that each comprehensive revision of a state's regional haze SIP must contain or provide for certain elements, including monitoring strategies, emissions inventories, and any reporting, recordkeeping and other measures needed to assess and report on visibility. A main requirement of this subsection is for states with Class I areas to submit monitoring strategies for measuring, characterizing, and reporting on visibility impairment. Section 51.308(f)(6)(ii) requires SIPs to provide for procedures by which monitoring data and other information are used in determining the contribution of emissions from within the state to regional haze visibility impairment at mandatory Class I Federal areas both within and outside the state. As noted previously, most regulatory requirements in § 51.308(f)(6) do not apply to states without Class I Areas.

However, § 51.308(f)(6)(iii) and (v) apply to all states that have emissions that contribute to a Class I Area, including Iowa. Section 51.308(f)(6)(iii) requires SIPs to provide procedures by which monitoring data and other information are used in determining the contribution of emissions from within the state to Regional Haze visibility impairment at mandatory Class I Federal areas in other states.

Iowa included details on the monitoring data the State used to estimate its visibility contribution to out-of-state Class I Areas, to address § 51.308(f)(6)(iii). Iowa relies on the IMPROVE monitoring network for monitoring at the Class I areas Iowa selected. We note Iowa included details on two IMPROVE protocol monitors previously operated by the State in section 9 of the state plan. Iowa's 2023 Ambient Air Monitoring Network Plan included the removal of the IMPROVE protocol monitors and was separately reviewed and approved by EPA. The removal of the IMPROVE protocol monitors does not impact this action because IMPROVE protocol monitors are not located at and do not represent visibility at mandatory Class I Federal areas. Therefore, neither the presence nor lack of IMPROVE protocol monitors has any direct impact on “determining the contribution of emissions from within the state to out-of-state Class I areas”.

Section 51.308(f)(6)(v) requires SIPs to provide for a statewide inventory of emissions of pollutants that are reasonably anticipated to cause or contribute to visibility impairment, including emissions for the most recent year for which data are available and estimates of future projected emissions. It also requires a commitment to update the inventory periodically. Section 51.308(f)(6)(v) also requires states to include estimates of future projected emissions and include a commitment to update the inventory periodically.

To address § 51.308(f)(6)(v), Iowa included emissions information by pollutant from LADCO's 2016 modeling inventory and from the 2017 NEI.^[41] The State's four factor analysis relied on emission data from 2009-2021. The State also included emission data from 2009-2021 for Iowa EGUs. Iowa also included future projections for 2028. Iowa committed to update the inventory periodically and comply with the Air Emissions Reporting Requirements. Based on Iowa's consideration of the emission data in their SIP submittal, the EPA proposes to find that Iowa has satisfied the emissions information requirement in § 51.308(f)(6)(v).

H. Requirements for Periodic Reports Describing Progress Towards the Reasonable Progress Goals

Section 51.308(f)(5) requires that periodic comprehensive revisions of states' regional haze plans also address the progress report requirements of 40 CFR 51.308(g)(1) through (5). The purpose of these requirements is to evaluate progress towards the applicable RPGs for each Class I area within the state and each Class I area outside the state that may be affected by emissions from within that state. Section 51.308(g)(1) and (2) apply to all states and require a description of the status of implementation of all measures included in a state's first implementation period regional haze plan and a summary of the emission reductions achieved through implementation of those measures. Section 51.308(g)(3) applies only to states with Class I areas within their borders and requires such states to assess current visibility conditions, changes in visibility relative to baseline (2000-2004) visibility conditions, and changes in visibility conditions relative to the period addressed in the first implementation period progress report. Section 51.308(g)(4) applies to all states and requires an analysis tracking changes in emissions of pollutants contributing to visibility impairment from all sources and sectors since the period addressed by the first implementation period progress report. This provision further specifies the year or years through which the analysis must extend depending on the type of source and the platform through which its emission information is reported. Finally, § 51.308(g)(5), which also applies to all states, requires an assessment of any significant changes in anthropogenic emissions within or outside the state have occurred since the period addressed by the first implementation period progress report, including whether such changes were anticipated and whether they have limited or impeded expected progress towards reducing emissions and improving visibility.

Iowa's submission describes the status of measures of the long-term strategy from the first implementation period. Iowa relied upon the Clean Air Interstate Rule (CAIR), later replaced by the Cross-State Air Pollution Rule (CSAPR), to satisfy long-term strategy obligations and Best Available Retrofit Technology (BART) requirements for EGUs. Iowa met all the identified reasonable measures during the first implementation period. Iowa's SIP submission includes EGU emission data demonstrating the reductions achieved throughout the State in table 10-1. The included emission data demonstrates a decrease in SO₂ and NO_X emissions since 2008, the year preceding CAIR implementation. Between 2008 and 2021, SO₂ and NO_X emissions declined by 81,258 and 30,078 tons, respectively.

The EPA proposes to find that Iowa has met the requirements of 40 CFR 51.308(g)(1) and (2) because its SIP submission describes the measures included in the long-term strategy from the first implementation period, as well as the status of their implementation and the emission reductions achieved through such implementation. Section 51.308(g)(3) does not apply to Iowa because it does not have a Class I Area.

Pursuant to § 51.308(g)(4), in section 10 of their submittal, Iowa provided a summary of NEI data for SO₂, NO_X, VOCs, PM₁₀, PM_2.5, and NH₃ for the years 2008 and 2017. The summarized emissions data in tables 10-2 and 10-3 of the state submission include anthropogenic emissions represented by point source EGU, point source non-EGU, nonpoint sources, on-road mobile sources and nonroad mobile sources; fire emissions including wildfire, prescribed fire and agriculture fire; and biogenic emissions from vegetation and soils. Iowa also included CAMD data in table 10-1 showing annual total EGU SO₂ and NO_X emissions for the time period from 2002 to 2021.

The reductions achieved through Iowa emission control measures are seen in the emissions inventory. Based on Iowa's SIP submittal, NO_X emissions have significantly declined in Iowa from 2008 to 2017 based on decreased emissions in the point EGU, point non-EGU, on-road and non-road sectors. NO_X emissions from the EGU sector decreased by 28,009 tpy, equating to a sector reduction of 55%. Total NO_X reductions decreased by 103,080 tpy, or 34%.

Emissions of SO₂ have shown a significant decline in Iowa from 2008 to 2017, particularly in the point EGU sector. During that period, SO₂ emissions from EGUs decreased by 86,091 tpy, equating to a sector reduction of 73%. Overall, SO₂ emissions declined by 125,347 tpy, or 76%.

Iowa's submission includes a summary of PM₁₀ emissions from all NEI data categories point EGU, point non-EGU, nonpoint, on-road, nonroad, and fire for 2008 and 2017 in Iowa. In Iowa, PM₁₀ emissions decreased in all categories except fire during that period. The PM₁₀ emissions decreased by more than 200,000 tpy, or 37%.

Iowa's submission shows a summary of PM_2.5 emissions from all NEI data categories for 2008 and 2017 in Iowa. PM_2.5 emissions decreased all categories except the fire sector. Decreases in PM_2.5 emissions are attributed to Federal new engine standards for nonroad vehicles and equipment, Federal and State regulations for on-road vehicles, and reductions in the nonpoint sector. The other large decrease in PM_2.5 emissions is primarily due to the decrease in emissions from fuel combustion at EGU and Industrial stationary sources.

VOC emissions declined in Iowa from 477,959 tpy in 2008 to 141,289 tpy in 2017. VOC decreases were achieved in all sectors except the fire sector.

Overall, ammonia (NH₃) emissions increased in Iowa from 2008 to 2017, primarily driven by increased emissions from the nonpoint source category. Nonpoint increases are due to reporting, grouping and methodology changes, as well as estimated emissions increase from agricultural sources. Overall, ammonia emissions increased by 11% in Iowa from 2008 to 2017.

The EPA is proposing to find that Iowa has satisfied the requirements of § 51.308(g)(4) by providing emissions information for NO_X, SO₂, PM₁₀, PM_2.5, VOCs, and NH₃ broken down by type of source.

Iowa uses the emissions trend data in the SIP submission ^[42] to support the assessment that anthropogenic haze-causing pollutant emissions in Iowa have decreased during the reporting period and that changes in emissions have not limited or impeded progress in reducing pollutant emissions and improving visibility. Overall, Iowa's 2017 emission inventories for NO_X, SO₂, PM₁₀, PM_2.5 , and VOCs were lower than their 2008 emission inventories and the forecasted 2018 emissions from Iowa's regional haze SIP for the first planning period ^[43] for those same pollutants emissions. The 2017 emission inventory for NH₃ were higher than the 2008 emission inventory and the forecasted 2018 emissions. However, the slight increase did not impede progress towards improving visibility in Class I Areas. The EPA is proposing to find that Iowa has met the requirements of § 51.308(g)(5).

I. Requirements for State and Federal Land Manager Coordination

Section 169A(d) of the CAA requires states to consult with FLMs before holding the public hearing on a proposed regional haze SIP, and to include a summary of the FLMs' conclusions and recommendations in the notice to the public. In addition, § 51.308(i)(2)'s FLM consultation provision requires a state to provide FLMs with an opportunity for consultation that is early enough in the state's policy analyses of its emission reduction obligation so that information and recommendations provided by the FLMs' can meaningfully inform the state's decisions on its long-term strategy. If the consultation has taken place at least 120 days before a public hearing or public comment period, the opportunity for consultation will be deemed early enough. Regardless, the opportunity for consultation must be provided at least sixty days before a public hearing or public comment period at the state level. Section 51.308(i)(2) also provides two substantive topics on which FLMs must be provided an opportunity to discuss with states: assessment of visibility impairment in any Class I area and recommendations on the development and implementation of strategies to address visibility impairment. Section 51.308(i)(3) requires states, in developing their implementation plans, to include a description of how they addressed FLMs' comments. Section 51.308(i)(4) requires states to provide for ongoing consultation between the state and FLM's on the implementation of the given plan and on development of future plan revisions or progress reports.

Iowa conducted informal FLM consultation early in the planning process to inform the state's decision-making process. As part of this early engagement with the FLMs, the U.S. Forest Service and the National Park Service each provided a recommendation to Iowa suggesting that it consider specific individual sources in its long-term strategies. In March 2020, the Forest Service identified three sources based on its review of emission rate data (lb/MMBtu) and results from a LADCO Q/d analysis. In June 2020, the National Park Service identified eleven Iowa sources using a Q/d(SO₂ + NO_X) threshold of 1.2 based on 2017 NEI emissions data for the non-EGUs and 2019 CAMD data for EGUs. As part of the consultation, Iowa reviewed its source selection methods and results with FLMs on June 3, 2020. On January 20, 2022, the state met with FLMs to informally discuss Iowa's four-factor analysis.

On October 11, 2022, Iowa submitted a draft Regional Haze SIP to the U.S. Forest Service, the U.S. Fish and Wildlife Service, and the National Park Service for a 60-day review and comment period pursuant to 40 CFR 51.308(i)(2).^[44] On November 3, 2022, Iowa held a virtual consultation meeting with the FLMs. Iowa received comments from the Forest Service and the National Park Service on December 8, 2022.^[45] Iowa responded to the FLM comments and included the responses in section 11.5 of its submission to EPA and their public notice, in accordance with the requirements in CAA section 169A(d) and § 51.308(i)(3). Notices of the proposed SIP, availability and the public hearing were published on IDNR's website, published in the Des Moines Register on February 13, 2023, and issued on the IDNR air quality listserv. A virtual public hearing on the proposed SIP revision was held on March 16, 2023. Written comments relevant to the proposal were accepted until the close of business March 16, 2023. Iowa's August 2023 SIP includes a commitment to ongoing consultation with FLMs in accordance with § 51.308(i)(4).

For the reasons stated above, the EPA proposes to find that Iowa has satisfied the requirements under 40 CFR 51.308(i) to consult with the FLMs on its regional haze SIP for the second implementation period.

Iowa's August 2023 SIP submission includes a commitment to submit periodic progress reports in accordance with § 51.308(f) and a commitment to evaluate progress towards the reasonable progress goal for each mandatory Class I Federal area located within the State and in each mandatory Class I Federal area located outside the State that may be affected by emissions from within the State in accordance with § 51.308(g).^[46]

VI. What action is the EPA proposing?

The EPA is proposing to approve the Iowa SIP submission received on August 15, 2023, as satisfying the regional haze requirements for the second implementation period contained in 40 CFR 51.308(f). We are processing this as a proposed action because we are soliciting comments on this proposed action. Final rulemaking will occur after consideration of any comments.

VII. Incorporation by Reference

In this document, the EPA is proposing to include regulatory text in an EPA final rule that includes incorporation by reference. In accordance with requirements of 1 CFR 51.5, the EPA is proposing to incorporate by reference “Iowa Regional Haze Plan for the Second Implementation Period” source specific requirements for MidAmerican Energy Company Louisa Station (Permit number 05-A-031-P6) and MidAmerican Energy Company Walter Scott Jr. Energy Center (Permit numbers 75-A-357-P9 and 03-A-425-P4), submitted on August 15, 2023. The EPA has made, and will continue to make, these materials generally available through https://www.regulations.gov and at the EPA Region 7 Office (please contact the person identified in the FOR FURTHER INFORMATION CONTACT section of this preamble for more information).

VIII. Environmental Justice Considerations

The EPA defines environmental justice (EJ) as “the fair treatment and meaningful involvement of all people regardless of race, color, national origin, or income with respect to the development, implementation, and enforcement of environmental laws, regulations, and policies.” The EPA further defines the term fair treatment to mean that “no group of people should bear a disproportionate burden of environmental harms and risks, including those resulting from the negative environmental consequences of industrial, governmental, and commercial operations or programs and policies.” ^[47]

Consideration of EJ is not required as part of this action, and there is no information in the record inconsistent with the stated goal of Executive Order 12898 of achieving environmental justice for people of color, low-income populations, and Indigenous peoples. However, recognizing the importance of environmental justice considerations to local communities, the EPA conducted an environmental justice screening analysis around the location of the facilities associated with this action to identify potential environmental stressors on these communities and the potential impacts of this action. The EPA is providing the information associated with this analysis for informational purposes only. The information provided herein is not a basis of the proposed action. The EPA conducted the screening analyses using EJScreen, an EJ mapping and screening tool that provides the EPA with a nationally consistent dataset and approach for combining various environmental and demographic indicators.^[48] The EJScreen tool presents these indicators at a Census block group (CBG) level or a larger user specified “buffer” area that covers multiple CBGs.^[49] An individual CBG is a cluster of contiguous blocks within the same census tract and generally contains between 600 and 3,000 people. EJScreen is not a tool for performing in-depth risk analysis, but is instead a screening tool that provides an initial representation of indicators related to EJ and is subject to uncertainty in some underlying data ( e.g., some environmental indicators are based on monitoring data which are not uniformly available; others are based on self-reported data).^[50] For informational purposes, we have summarized EJScreen data within larger “buffer” areas covering multiple block groups and representing the average resident within the buffer areas surrounding the facilities selected by Iowa for further control analysis. EJScreen environmental indicators help screen for locations where residents may experience a higher overall pollution burden than would be expected for a block group with the same total population in the U.S. These indicators of overall pollution burden include estimates of ambient PM_2.5 and ozone concentration, a score for traffic proximity and volume, percentage of pre-1960 housing units (lead paint indicator), and scores for proximity to Superfund sites, risk management plan (RMP) sites, and hazardous waste facilities.^[51] EJScreen also provides information on demographic indicators, including percent low-income, communities of color, linguistic isolation, and less than high school education.

The EPA prepared EJScreen reports covering buffer areas of approximately 6-mile radius around the facilities selected by Iowa for further analysis. For each facility, the EPA indicates in the following statements whether there is an environmental or socioeconomic indicator for the selected source area above the 80th percentile nationally.^[52] These indicators are displayed in the table on page 3 of each report. The report for Walter Scott Jr. Energy Center showed environmental indicators greater than the 80th national percentiles superfund proximity and RMP facility proximity. The report for Louis Generating Station does not include environmental or socioeconomic indicators greater than the 80th national percentiles. The full, detailed EJScreen reports for the two facilities selected by Iowa for further analysis are provided in the docket for this rulemaking for informational purposes only.

This action is proposing to approve Iowa's second planning period regional haze plan as meeting the requirements of the CAA and the EPA's RHR. Exposure to PM and SO₂ is associated with significant public health effects. Short-term exposures to SO₂ can harm the human respiratory system and make breathing difficult. People with asthma, particularly children, are sensitive to these effects of SO₂ .^[53] Exposure to PM can affect both the lungs and heart and is associated with: premature death in people with heart or lung disease, nonfatal heart attacks, irregular heartbeat, aggravated asthma, decreased lung function, and increased respiratory symptoms, such as irritation of the airways, coughing or difficulty breathing. People with heart or lung diseases or conditions, children, and older adults are the most likely to be affected by PM exposure.^[54] We expect that this action and resulting emissions reductions will generally be neutral or contribute to reduced environmental and health impacts on all populations near both Walter Scott Jr. Energy Center and Louisa Generating Station. There is nothing in the record which indicates that this proposed action, if finalized, would have disproportionately high or adverse human health or environmental effects on communities with environmental justice concerns.

This action is proposing to approve Iowa's second planning period regional haze plan as meeting the requirements of the CAA and the EPA's RHR. However, as stated previously, the EPA is not required to, but has provided the information associated with the environmental justice analysis for informational purposes only. The information provided herein does not serve as a basis of the proposed action.

IX. 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, EPA's role is to approve state choices, provided that they meet the criteria of the CAA. Accordingly, this action merely approves state law as meeting Federal requirements and does not impose additional requirements beyond those imposed by state law. For that reason, this action:

• Is not a significant regulatory action subject to review by the Office of Management and Budget under Executive Orders 12866 (58 FR 51735, October 4, 1993) and 14094 (88 FR 21879, April 11, 2023);
• 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 inExecutive Order 13132 (64 FR 43255, August 10, 1999);
• Is not subject toExecutive Order 13045 (62 FR 19885, April 23, 1997) because it approves a state program;
• Is not a significant regulatory action subject toExecutive Order 13211 (66 FR 28355, May 22, 2001); and
• Is not subject to requirements of section 12(d) of the National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 note) because application of those requirements would be inconsistent with the CAA.

Executive Order 12898 (Federal Actions To Address Environmental Justice in Minority Populations and Low-Income Populations, 59 FR 7629, February 16, 1994) directs Federal agencies to identify and address “disproportionately high and adverse human health or environmental effects” of their actions on minority populations and low-income populations to the greatest extent practicable and permitted by law. EPA defines environmental justice (EJ) as “the fair treatment and meaningful involvement of all people regardless of race, color, national origin, or income with respect to the development, implementation, and enforcement of environmental laws, regulations, and policies.” EPA further defines the term fair treatment to mean that “no group of people should bear a disproportionate burden of environmental harms and risks, including those resulting from the negative environmental consequences of industrial, governmental, and commercial operations or programs and policies.” The Iowa Department of Natural Resources did not evaluate environmental justice considerations as part of its SIP submittal; the CAA and applicable implementing regulations neither prohibit nor require such an evaluation. The EPA performed an environmental justice analysis, as is described above in the section titled, “Environmental Justice Considerations.” The analysis was done for the purpose of providing additional context and information about this rulemaking to the public, not as a basis of the action. Due to the nature of the action being taken here, this action is expected to have a neutral to positive impact on the air quality of the affected area. In addition, there is no information in the record upon which this decision is based inconsistent with the stated goal of E.O. 12898 of achieving environmental justice for people of color, low-income populations, and Indigenous peoples.

In addition, this proposed rulemaking action, pertaining to Iowa regional haze SIP submission for the second planning period, 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 and will not impose substantial direct costs on Tribal governments or preempt Tribal law as specified by Executive Order 13175 (65 FR 67249, November 9, 2000).

List of Subjects in 40 CFR Part 52

• Environmental protection
• Air pollution control
• Incorporation by reference
• Nitrogen dioxide
• Ozone
• Particulate matter
• Sulfur oxides

Dated: July 22, 2024.

Meghan A. McCollister,

Regional Administrator, Region 7.

Title 40, chapter I, of the Code of Federal Regulations is proposed to be amended as follows:

PART 52—APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS

1. The authority citation for part 52 continues to read as follows:

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

Subpart Q—Iowa

2. In § 52.820:

a. The table in paragraph (d) is amended by adding the entries “(170)”, “(171)”, and “(172)” in numerical order.

b. The table in paragraph (e) is amended by adding the entry “(56)” in numerical order.

The additions read as follows:

§ 52.820

Identification of plan.

* * * * *

(d) * * *

EPA-Approved Iowa Source-Specific Orders/Permits

Name of source	Order/ permit No.	State effective date	EPA approval date	Explanation
*         *         *         *         *         *         *
(170) MidAmerican Energy Co.—Louisa Station	05-A-031-P6	7/20/2023	[Date of publication of the final rule in the Federal Register ], [ Federal Register citation of the final rule]	Regional Haze Plan for the second implementation period; condition 11 of the permit is not part of the SIP.
(171) MidAmerican Energy Co—Walter Scott Jr. Energy Center	75-A-357-P9	7/20/2023	[Date of publication of the final rule in the Federal Register ], [ Federal Register citation of the final rule]	Regional Haze Plan for the second implementation period; condition 11 of the permit is not part of the SIP.
(172) MidAmerican Energy Company—Walter Scott, Jr. Energy Center	03-A-425-P4	12/5/2011	[Date of publication of the final rule in the Federal Register ], [ Federal Register citation of the final rule]	Regional Haze Plan for the second implementation period; condition 6 of the permit is not part of the SIP.

(e) * * *

EPA-Approved Iowa Nonregulatory Provisions

Name of nonregulatory SIP provision	Applicable geographic or nonattainment area	State submittal date	EPA approval date	Explanation
*         *         *         *         *         *         *
(56) Iowa Regional Haze Plan for the Second Implementation Period	Statewide	8/15/2023	[Date of publication of the final rule in the Federal Register ], [ Federal Register citation of the final rule]	[EPA-R07-OAR-2024-0313; FRL-12096-01-R7].