83338 Federal Register / Vol. 89, No. 199 / Tuesday, October 15, 2024 / Proposed Rules 

1See CAA section 110(k)(3) and July 1992 EPA 

memorandum titled ‘‘Processing of State 

Implementation Plan (SIP) Submittals’’ from John 

Calcagni, at https://www.epa.gov/sites/default/files/ 

2015-07/documents/procsip.pdf. 

ENVIRONMENTAL PROTECTION 

AGENCY 

40 CFR Part 52 

[EPA–R06–OAR–2021–0539; FRL–12282– 

01–R6] 

Air Quality State Implementation 

Plans; Partial Approval, Partial 

Disapproval and Promulgation; Texas; 

Regional Haze 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Proposed rule. 

SUMMARY: The Environmental Protection 

Agency (EPA) is proposing to partially 

approve and partially disapprove the 

regional haze State implementation plan 

(SIP) revision submitted by Texas on 

July 20, 2021, under the Clean Air Act 

(CAA) and EPA’s Regional Haze Rule 

(RHR) for the program’s second 

implementation period. Texas’s SIP 

submission addresses the requirement 

that states must periodically revise their 

long-term strategies for making 

reasonable progress towards the 

national goal of preventing any future, 

and remedying any existing, 

anthropogenic impairment of visibility, 

including regional haze, in mandatory 

Class I Federal areas. The SIP 

submission also addresses other 

applicable requirements for the second 

implementation period of the regional 

haze program. The EPA is taking this 

action pursuant to sections 110 and 

169A of the Clean Air Act. 

DATES: Written comments must be 

received on or before November 14, 

2024. 

ADDRESSES: Submit your comments, 

identified by Docket ID No. EPA–R06– 

OAR–2021–0539 at https://

www.regulations.gov. Follow the online 

instructions for submitting comments. 

Once submitted, comments cannot be 

edited or removed from Regulations.gov. 

The EPA may publish any comment 

received to its public docket. Do not 

submit electronically any information 

you consider to be Confidential 

Business Information (CBI) or other 

information whose disclosure is 

restricted by statute. Multimedia 

submissions (audio, video, etc.) must be 

accompanied by a written comment. 

The written comment is considered the 

official comment and should include 

discussion of all points you wish to 

make. The EPA will generally not 

consider comments or comment 

contents located outside of the primary 

submission (i.e., on the web, cloud, or 

other file sharing system). For 

additional submission methods, the full 

EPA public comment policy, 

information about CBI or multimedia 

submissions, and general guidance on 

making effective comments, please visit 

https://www.epa.gov/dockets/ 

commenting-epa-dockets. For additional 

submission methods, please contact the 

person identified in the FOR FURTHER

INFORMATION CONTACT section. For the 

full EPA public comment policy, 

information about CBI or multimedia 

submissions, and general guidance on 

making effective comments, please visit 

https://www.epa.gov/dockets/ 

commenting-epa-dockets. 

Docket: The index to the docket for 

this action is available electronically at 

www.regulations.gov. While all 

documents in the docket are listed in 

the index, some information may not be 

publicly available due to docket file size 

restrictions or content (e.g., CBI). 

FOR FURTHER INFORMATION CONTACT: 

Jennifer Huser, U.S. Environmental 

Protection Agency, Region 6, 1201 Elm 

St., Suite 500, Dallas, Texas 75270, at 

(214) 665–7347, or by email at 

Huser.Jennifer@epa.gov. 

SUPPLEMENTARY INFORMATION: 

Throughout this document wherever 

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

the EPA. 

Table of Contents 

I. What action is the EPA proposing? 

II. Background and Requirements for 

Regional Haze Plans 

A. Regional Haze Background 

B. Roles of Agencies in Addressing 

Regional Haze 

III. Requirements for Regional Haze Plans for 

the Second Implementation Period 

A. Identification of Class I Areas 

B. Calculations of Baseline, Current, and 

Natural Visibility Conditions; Progress to 

Date; and the Uniform Rate of Progress 

C. Long-Term Strategy for Regional Haze 

D. Reasonable Progress Goals 

E. Monitoring Strategy and Other State 

Implementation Plan Requirements 

F. Requirements for Periodic Reports 

Describing Progress Towards the 

Reasonable Progress Goals 

G. Requirements for State and Federal 

Land Manager Coordination 

IV. The EPA’s Evaluation of Texas’s Regional 

Haze Submission for the Second 

Implementation Period 

A. Background on Texas’s First 

Implementation Period SIP Submission 

B. Texas’s Second Implementation Period 

SIP Submission and the EPA’s 

Evaluation 

C. Identification of Class I Areas 

1. Texas Class I Areas 

2. Identification of Impacted Class I Areas 

Outside the State 

D. Calculations of Baseline, Current, and 

Natural Visibility Conditions; Progress to 

Date; and the Uniform Rate of Progress 

E. Long-Term Strategy for Regional Haze 

1. Source Selection 

2. Four Factor Analysis 

3. Additional Long-Term Strategy 

Requirements 

F. Reasonable Progress Goals 

G. Reasonably Attributable Visibility 

Impairment (RAVI) 

H. Monitoring Strategy and Other 

Implementation Plan Requirements 

I. Requirements for Periodic Reports 

Describing Progress Towards the 

Reasonable Progress Goals 

J. Requirements for State and Federal Land 

Manager Coordination 

V. Proposed Action 

VI. Environmental Justice Considerations 

VII. Statutory and Executive Order Reviews 

I. What action is the EPA proposing? 

On July 20, 2021, the Texas 

Commission on Environmental Quality 

(TCEQ) submitted a plan (‘‘2021 Texas 

Regional Haze Plan’’ or ‘‘Texas RH SIP’’) 

to the EPA to satisfy the regional haze 

program requirements pursuant to CAA 

sections 169A and 40 CFR 51.308. The 

EPA is proposing to partially approve 

and partially disapprove Texas’s 

Regional Haze plan for the second 

planning (implementation) period. 

Consistent with section 110(k)(3) of the 

CAA, the EPA may partially approve 

portions of a submittal if those elements 

meet all applicable requirements and 

may disapprove the remainder so long 

as the elements are fully separable.1 As 

required by section 169A of the CAA, 

the Federal RHR calls for State and 

Federal agencies to work together to 

improve visibility in 156 national parks 

and wilderness areas. The rule requires 

the states, in coordination with the EPA, 

National Park Service (NPS), U.S. Fish 

and Wildlife Service (FWS), Forest 

Service (FS), and other interested 

parties, to develop and implement air 

quality protection plans to reduce the 

pollution that causes visibility 

impairment. Visibility impairing 

pollutants include fine and coarse 

particulate matter (PM) (e.g., sulfates, 

nitrates, organic carbon, elemental 

carbon, and soil dust) and their 

precursors (e.g., sulfur dioxide (SO2), 

nitrogen oxides (NOX), and, in some 

cases, volatile organic compounds 

(VOC) and ammonia (NH3)). As 

discussed in further detail below, the 

EPA is proposing to find that Texas has 

submitted a Regional Haze plan that 

does not meet all the Regional Haze 

requirements for the second planning 

period. For the reasons described in this 

document, the EPA is proposing to 

approve the elements of Texas’s plan 

related to requirements contained in 40 


khammond on DSKJM1Z7X2PROD with PROPOSALS2
Federal Register / Vol. 89, No. 199 / Tuesday, October 15, 2024 / Proposed Rules 83339 

2 40 CFR 51.308(f)(5) requires that the second 

planning period SIP revision address the 

requirements listed in (g)(1) through (g)(5). 

3Areas statutorily designated as mandatory Class 

I Federal areas consist of national parks exceeding 

6,000 acres, wilderness areas and national memorial 

parks exceeding 5,000 acres, and all international 

parks that were in existence on August 7, 1977. 

CAA 162(a). There are 156 mandatory Class I areas. 

The list of areas to which the requirements of the 

visibility protection program apply is in 40 CFR 

part 81, subpart D. 

4 In addition to the generally applicable regional 

haze provisions at 40 CFR 51.308, the EPA also 

promulgated regulations specific to addressing 

regional haze visibility impairment in Class I areas 

on the Colorado Plateau at 40 CFR 51.309. The 

latter regulations are applicable only for specific 

jurisdictions’ regional haze plans submitted no later 

than December 17, 2007, and thus are not relevant 

here. 

5There are several ways to measure the amount 

of visibility impairment, i.e., haze. One such 

measurement is the deciview, which is the 

principal metric used by the RHR. Under many 

circumstances, a change in one deciview will be 

perceived by the human eye to be the same on both 

clear and hazy days. The deciview is unitless. It is 

proportional to the logarithm of the atmospheric 

extinction of light, which is the perceived dimming 

of light due to its being scattered and absorbed as 

it passes through the atmosphere. Atmospheric light 

extinction (bext) is a metric used for expressing 

visibility and is measured in inverse megameters 

(Mm 1). The EPA’s Guidance on Regional Haze 

State Implementation Plans for the Second 

Implementation Period (‘‘2019 Guidance’’) offers 

the flexibility for the use of light extinction in 

certain cases. Light extinction can be simpler to use 

in calculations than deciviews, since it is not a 

logarithmic function. See, e.g., 2019 Guidance at 16, 

19, https://www.epa.gov/visibility/guidanceregional-haze-state-implementation-plans-secondimplementation-period, The EPA Office of Air 

Quality Planning and Standards, Research Triangle 

Park (August 20, 2019). The formula for the 

deciview is 10 ln (bext)/10 Mm¥1). 40 CFR 51.301. 

6The RHR expresses the statutory requirement for 

states to submit plans addressing out-of-state Class 

I areas by providing that states must address 

visibility impairment ‘‘in each mandatory Class I 

Federal area located outside the State that may be 

affected by emissions from within the State.’’ 40 

CFR 51.308(d), (f). 

7 In addition to each of the fifty states, the EPA 

also concluded that the Virgin Islands and District 

of Columbia must also submit regional haze SIPs 

because they either contain a Class I area or contain 

sources whose emissions are reasonably anticipated 

to contribute regional haze in a Class I area. See 40 

CFR 51.300(b), (d)(3). 

CFR 51.308(f)(1), (f)(4), (f)(5),2 and (f)(6). 

The EPA is proposing to disapprove the 

elements of Texas’s plan related to 

requirements contained in 40 CFR 

51.308(f)(2), (f)(3), and (i). The State’s 

submission can be found in the docket 

for this action. 

II. Background and Requirements for 

Regional Haze Plans 

A. Regional Haze Background 

In the 1977 CAA Amendments, 

Congress created a program for 

protecting visibility in the nation’s 

mandatory Class I Federal areas, which 

include certain national parks and 

wilderness areas.3 CAA 169A. The CAA 

establishes as a national goal the 

‘‘prevention of any future, and the 

remedying of any existing, impairment 

of visibility in mandatory class I Federal 

areas which impairment results from 

manmade air pollution.’’ CAA 

169A(a)(1). The CAA further directs the 

EPA to promulgate regulations to assure 

reasonable progress toward meeting this 

national goal. CAA 169A(a)(4). On 

December 2, 1980, the EPA promulgated 

regulations to address visibility 

impairment in mandatory Class I 

Federal areas (hereinafter referred to as 

‘‘Class I areas’’) that is ‘‘reasonably 

attributable’’ to a single source or small 

group of sources. (45 FR 80084, 

December 2, 1980). These regulations, 

codified at 40 CFR 51.300 through 

51.307, represented the first phase of the 

EPA’s efforts to address visibility 

impairment. In 1990, Congress added 

section 169B to the CAA to further 

address visibility impairment, 

specifically, impairment from regional 

haze. CAA 169B. The EPA promulgated 

the RHR, codified at 40 CFR 51.308,4 on 

July 1, 1999. (64 FR 35714, July 1, 1999). 

These regional haze regulations are a 

central component of the EPA’s 

comprehensive visibility protection 

program for Class I areas. 

Regional haze is visibility impairment 

that is produced by a multitude of 

anthropogenic sources and activities 

which are located across a broad 

geographic area and that emit pollutants 

that impair visibility. Visibility 

impairing pollutants include fine and 

coarse particulate matter (PM) (e.g., 

sulfates, nitrates, organic carbon, 

elemental carbon, and soil dust) and 

their precursors (e.g., sulfur dioxide 

(SO2), nitrogen oxides (NOX), and, in 

some cases, volatile organic compounds 

(VOC) and ammonia (NH3)). Fine 

particle precursors react in the 

atmosphere to form fine particulate 

matter (PM2.5), which impairs visibility 

by scattering and absorbing light. 

Visibility impairment reduces the 

perception of clarity and color, as well 

as visible distance.5

To address regional haze visibility 

impairment, the 1999 RHR established 

an iterative planning process that 

requires both states in which Class I 

areas are located and states ‘‘the 

emissions from which may reasonably 

be anticipated to cause or contribute to 

any impairment of visibility’’ in a Class 

I area to periodically submit SIP 

revisions to address such impairment. 

CAA 169A(b)(2); 6 see also 40 CFR 

51.308(b), (f) (establishing submission 

dates for iterative regional haze SIP 

revisions); (64 FR at 35768, July 1, 

1999). Under the CAA, each SIP 

submission must contain ‘‘a long-term 

(ten to fifteen years) strategy for making 

reasonable progress toward meeting the 

national goal,’’ CAA 169A(b)(2)(B); the 

initial round of SIP submissions also 

had to address the statutory requirement 

that certain older, larger sources of 

visibility impairing pollutants install 

and operate the best available retrofit 

technology (BART). CAA 169A(b)(2)(A); 

40 CFR 51.308(d), (e). States’ first 

regional haze SIPs were due by 

December 17, 2007, 40 CFR 51.308(b), 

with subsequent SIP submissions 

containing updated long-term strategies 

originally due July 31, 2018, and every 

ten years thereafter. (64 FR at 35768, 

July 1, 1999). The EPA established in 

the 1999 RHR that all states either have 

Class I areas within their borders or 

‘‘contain sources whose emissions are 

reasonably anticipated to contribute to 

regional haze in a Class I area’’; 

therefore, all states must submit regional 

haze SIPs.7 Id. at 35721. 

Much of the focus in the first 

implementation period of the regional 

haze program, which ran from 2007 

through 2018, was on satisfying states’ 

BART obligations. First implementation 

period SIPs were additionally required 

to contain long-term strategies for 

making reasonable progress toward the 

national visibility goal, of which BART 

is one component. The core required 

elements for the first implementation 

period SIPs (other than BART) are laid 

out in 40 CFR 51.308(d). Those 

provisions required that states 

containing Class I areas establish 

reasonable progress goals (RPGs) that 

are measured in deciviews and reflect 

the anticipated visibility conditions at 

the end of the implementation period 

including from implementation of 

states’ long-term strategies. The first 

planning period RPGs were required to 

provide for an improvement in visibility 

for the most impaired days over the 

period of the implementation plan and 

ensure no degradation in visibility for 

the least impaired days over the same 

period. In establishing the RPGs for any 

Class I area in a State, the State was 

required to consider four statutory 

factors: the costs of compliance, 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. CAA 

169A(g)(1); 40 CFR 51.308(d)(1). 

States were also required to calculate 

baseline (using the five year period of 

2000–2004) and natural visibility 

conditions (i.e., visibility conditions 

without anthropogenic visibility 


khammond on DSKJM1Z7X2PROD with PROPOSALS2
83340 Federal Register / Vol. 89, No. 199 / Tuesday, October 15, 2024 / Proposed Rules 

8The EPA established the URP framework in the 

1999 RHR to provide ‘‘an equitable analytical 

approach’’ to assessing the rate of visibility 

improvement at Class I areas across the country. 

The starting point for the URP analysis is 2004 and 

the endpoint was calculated based on the amount 

of visibility improvement that was anticipated to 

result from implementation of existing CAA 

programs over the period from the mid-1990s to 

approximately 2005. Assuming this rate of progress 

would continue into the future, the EPA determined 

that natural visibility conditions would be reached 

in 60 years, or 2064 (60 years from the baseline 

starting point of 2004). However, the EPA did not 

establish 2064 as the year by which the national 

goal must be reached. 64 FR at 35731–32. That is, 

the URP and the 2064 date are not enforceable 

targets but are rather tools that ‘‘allow for analytical 

comparisons between the rate of progress that 

would be achieved by the state’s chosen set of 

control measures and the URP.’’ (82 FR 3078, 3084, 

January 10, 2017). 

9The EPA’s regulations define ‘‘Federal Land 

Manager’’ as ‘‘the Secretary of the department with 

authority over the Federal Class I area (or the 

Secretary’s designee) or, with respect to RooseveltCampobello International Park, the Chairman of the 

Roosevelt-Campobello International Park 

Commission.’’ 40 CFR 51.301. 

10 Guidance on Regional Haze State 

Implementation Plans for the Second 

Implementation Period. https://www.epa.gov/ 

visibility/guidance-regional-haze-stateimplementation-plans-second-implementationperiod The EPA Office of Air Quality Planning and 

Standards, Research Triangle Park (August 20, 

2019). 

11Clarifications Regarding Regional Haze State 

Implementation Plans for the Second 

Implementation Period. https://www.epa.gov/ 

system/files/documents/2021-07/clarificationsregarding-regional-haze-state-implementationplans-for-the-second-implementation-period.pdf. 

The EPA Office of Air Quality Planning and 

Standards, Research Triangle Park (July 8, 2021). 

12Technical Guidance on Tracking Visibility 

Progress for the Second Implementation Period of 

the Regional Haze Program. https://www.epa.gov/ 

visibility/technical-guidance-tracking-visibilityprogress-second-implementation-period-regional 

The EPA Office of Air Quality Planning and 

Standards, Research Triangle Park. (December 20, 

2018). 

13Recommendation for the Use of Patched and 

Substituted Data and Clarification of Data 

Completeness for Tracking Visibility Progress for 

the Second Implementation Period of the Regional 

Haze Program. https://www.epa.gov/visibility/ 

memo-and-technical-addendum-ambient-datausage-and-completeness-regional-haze-program 

The EPA Office of Air Quality Planning and 

Standards, Research Triangle Park (June 3, 2020). 

impairment) for each Class I area, and 

to calculate the linear rate of progress 

needed to attain natural visibility 

conditions, assuming a starting point of 

baseline visibility conditions in 2004 

and ending with natural conditions in 

2064. This linear interpolation is known 

as the uniform rate of progress (URP) 

and is used as a tracking metric to help 

states assess the amount of progress they 

are making towards the national 

visibility goal over time in each Class I 

area.8 40 CFR 51.308(d)(1)(i)(B), (d)(2). 

The 1999 RHR also provided that States’ 

long-term strategies must include the 

‘‘enforceable emissions limitations, 

compliance, schedules, and other 

measures as necessary to achieve the 

reasonable progress goals.’’ 40 CFR 

51.308(d)(3). In establishing their longterm strategies, states are required to 

consult with other states that also 

contribute to visibility impairment in a 

given Class I area and include all 

measures necessary to obtain their 

shares of the emission reductions 

needed to meet the RPGs. 40 CFR 

51.308(d)(3)(i), (ii). Section 51.308(d) 

also contains seven additional factors 

states must consider in formulating their 

long-term strategies, 40 CFR 

51.308(d)(3)(v), as well as provisions 

governing monitoring and other 

implementation plan requirements. 40 

CFR 51.308(d)(4). Finally, the 1999 RHR 

required states to submit periodic 

progress reports—SIP revisions due 

every five years that contain information 

on states’ implementation of their 

regional haze plans and an assessment 

of whether anything additional is 

needed to make reasonable progress, see 

40 CFR 51.308(g), (h)—and to consult 

with the Federal Land Manager(s) 9

(FLMs) responsible for each Class I area 

according to the requirements in CAA 

169A(d) and 40 CFR 51.308(i). 

On January 10, 2017, the EPA 

promulgated revisions to the RHR, (82 

FR 3078, January 10, 2017), that apply 

for the second and subsequent 

implementation periods. The 2017 

rulemaking made several changes to the 

requirements for regional haze SIPs to 

clarify States’ obligations and streamline 

certain regional haze requirements. The 

revisions to the regional haze program 

for the second and subsequent 

implementation periods focused on the 

requirement that States’ SIPs contain 

long-term strategies for making 

reasonable progress towards the 

national visibility goal. The reasonable 

progress requirements as revised in the 

2017 rulemaking (referred to here as the 

2017 RHR Revisions) are codified at 40 

CFR 51.308(f). Among other changes, 

the 2017 RHR Revisions adjusted the 

deadline for States to submit their 

second implementation period SIPs 

from July 31, 2018, to July 31, 2021, 

clarified the order of analysis and the 

relationship between RPGs and the 

long-term strategy, and focused on 

making visibility improvements on the 

days with the most anthropogenic 

visibility impairment, as opposed to the 

days with the most visibility 

impairment overall. The EPA also 

revised requirements of the visibility 

protection program related to periodic 

progress reports and FLM consultation. 

The specific requirements applicable to 

second implementation period regional 

haze SIP submissions are addressed in 

detail below. 

The EPA provided guidance to the 

states for their second implementation 

period SIP submissions in the preamble 

to the 2017 RHR Revisions as well as in 

subsequent, stand-alone guidance 

documents. In August 2019, the EPA 

issued ‘‘Guidance on Regional Haze 

State Implementation Plans for the 

Second Implementation Period’’ (‘‘2019 

Guidance’’).10 On July 8, 2021, the EPA 

issued a memorandum containing 

‘‘Clarifications Regarding Regional Haze 

State Implementation Plans for the 

Second Implementation Period’’ (‘‘2021 

Clarifications Memo’’).11 Additionally, 

the EPA further clarified the 

recommended procedures for processing 

ambient visibility data and optionally 

adjusting the URP to account for 

international anthropogenic and 

prescribed fire impacts in two technical 

guidance documents: the December 

2018 ‘‘Technical Guidance on Tracking 

Visibility Progress for the Second 

Implementation Period of the Regional 

Haze Program’’ (‘‘2018 Visibility 

Tracking Guidance’’),12 and the June 

2020 ‘‘Recommendation for the Use of 

Patched and Substituted Data and 

Clarification of Data Completeness for 

Tracking Visibility Progress for the 

Second Implementation Period of the 

Regional Haze Program’’ and associated 

Technical Addendum (‘‘2020 Data 

Completeness Memo’’).13

As explained in the 2021 

Clarifications Memo, the EPA intends 

the second implementation period of 

the regional haze program to secure 

meaningful reductions in visibility 

impairing pollutants that build on the 

significant progress states have achieved 

to date. The Agency also recognizes that 

analyses regarding reasonable progress 

are State-specific and that, based on 

states’ and sources’ individual 

circumstances, what constitutes 

reasonable reductions in visibility 

impairing pollutants will vary from 

State-to-State. While there exist many 

opportunities for states to leverage both 

ongoing and upcoming emission 

reductions under other CAA programs, 

the Agency expects states to undertake 

rigorous reasonable progress analyses 

that identify further opportunities to 

advance the national visibility goal 

consistent with the statutory and 

regulatory requirements. See generally 

2021 Clarifications Memo. This is 

consistent with Congress’s 

determination that a visibility 

protection program is needed in 

addition to the CAA’s National Ambient 

Air Quality Standards and Prevention of 

Significant Deterioration programs, as 


khammond on DSKJM1Z7X2PROD with PROPOSALS2
Federal Register / Vol. 89, No. 199 / Tuesday, October 15, 2024 / Proposed Rules 83341 

14See, e.g., H.R. Rep No. 95–294 at 205 (‘‘In 

determining how to best remedy the growing 

visibility problem in these areas of great scenic 

importance, the committee realizes that as a matter 

of equity, the national ambient air quality standards 

cannot be revised to adequately protect visibility in 

all areas of the country.’’), (‘‘the mandatory class I 

increments of [the PSD program] do not adequately 

protect visibility in class I areas’’). 

15RPOs are sometimes also referred to as ‘‘multijurisdictional organizations,’’ or MJOs. For the 

purposes of this notice, the terms RPO and MJO are 

synonymous. 

16The EPA explained in the 2017 RHR Revisions 

that we were adopting new regulatory language in 

40 CFR 51.308(f) that, unlike the structure in 

51.308(d), ‘‘tracked the actual planning sequence.’’ 

(82 FR 3091, January 10, 2017). 

17The five ‘‘additional factors’’ for consideration 

in section 51.308(f)(2)(iv) are distinct from the four 

factors listed in CAA section 169A(g)(1) and 40 CFR 

51.308(f)(2)(i) that states must consider and apply 

to sources in determining reasonable progress. 

further emission reductions may be 

necessary to adequately protect 

visibility in Class I areas throughout the 

country.14

B. Roles of Agencies in Addressing 

Regional Haze 

Because the air pollutants and 

pollution affecting visibility in Class I 

areas can be transported over long 

distances, successful implementation of 

the regional haze program requires longterm, regional coordination among 

multiple jurisdictions and agencies that 

have responsibility for Class I areas and 

the emissions that impact visibility in 

those areas. To address regional haze, 

states need to develop strategies in 

coordination with one another, 

considering the effect of emissions from 

one jurisdiction on the air quality in 

another. Five regional planning 

organizations (RPOs),15 which include 

representation from State and Tribal 

governments, the EPA, and FLMs, were 

developed in the lead-up to the first 

implementation period to address 

regional haze. RPOs evaluate technical 

information to better understand how 

emissions from State and Tribal land 

impact Class I areas across the country, 

pursue the development of regional 

strategies to reduce emissions of 

particulate matter and other pollutants 

leading to regional haze, and help states 

meet the consultation requirements of 

the RHR. 

The Central Regional Air Planning 

Association (CenRAP), one of the five 

RPOs described above, that Texas was a 

member of during the first planning 

period, was a collaborative effort of 

State governments, Tribal governments, 

and Federal agencies established to 

initiate and coordinate activities 

associated with the management of 

regional haze, visibility, and other air 

quality issues in parts of the Great 

Plains, Midwest, Southwest, and South 

Regions of the United States. 

After the first planning period SIPs 

were submitted, the planning was 

shifted to the Central State Air 

Resources Agencies (CenSARA). 

CenSARA was established to promote 

the exchange of air quality information, 

knowledge, experience, and data among 

and between participating organizations 

and other interested parties. It supports 

the membership with training and 

policy and technical projects. CenSARA 

supports and promotes collaborative 

efforts of State governments to initiate 

and coordinate activities associated 

with the management of regional haze 

and other air quality issues in parts of 

the Great Plains, Midwest, Southwest, 

and South Regions of the United States. 

Member states include: Arkansas, Iowa, 

Kansas, Louisiana, Missouri, Nebraska, 

Oklahoma, and Texas. Unlike CenRAP, 

CenSARA has solely State and local 

government members. However, 

CenSARA does reach out to Tribal and 

Federal partners. The Federal partners 

of CenSARA are the EPA, the NPS, the 

FWS, and FS. 

III. Requirements for Regional Haze 

Plans for the Second Implementation 

Period 

Under the CAA and EPA’s 

regulations, all 50 States, the District of 

Columbia, and the U.S. Virgin Islands 

are required to submit regional haze 

SIPs satisfying the applicable 

requirements for the second 

implementation period of the regional 

haze program by July 31, 2021. Each 

state’s SIP must contain a long-term 

strategy for making reasonable progress 

toward meeting the national goal of 

remedying any existing and preventing 

any future anthropogenic visibility 

impairment in Class I areas. CAA 

169A(b)(2)(B). To this end, § 51.308(f) 

lays out the process by which states 

determine what constitutes their longterm strategies, with the order of the 

requirements in § 51.308(f)(1) through 

(f)(3) generally mirroring the order of 

the steps in the reasonable progress 

analysis 16 and (f)(4) through (f)(6) 

containing additional, related 

requirements. Broadly speaking, a State 

first must identify the Class I areas 

within the State and determine the Class 

I areas outside the State in which 

visibility may be affected by emissions 

from the State. These are the Class I 

areas that must be addressed in the 

state’s long-term strategy. See 40 CFR 

51.308(f), (f)(2). For each Class I area 

within its borders, a State must then 

calculate the baseline, current, and 

natural visibility conditions for that 

area, as well as the visibility 

improvement made to date and the URP. 

See 40 CFR 51.308(f)(1). Each State 

having a Class I area and/or emissions 

that may affect visibility in a Class I area 

must then develop a long-term strategy 

that includes the enforceable emission 

limitations, compliance schedules, and 

other measures that are necessary to 

make reasonable progress in such areas. 

A reasonable progress determination is 

based on applying the four factors in 

CAA section 169A(g)(1) to sources of 

visibility impairing pollutants that the 

State has selected to assess for controls 

for the second implementation period. 

Additionally, as further explained 

below, the RHR at 40 CFR 

51.3108(f)(2)(iv) separately provides five 

‘‘additional factors’’ 17 that states must 

consider in developing their long-term 

strategies. See 40 CFR 51.308(f)(2). A 

State evaluates potential emission 

reduction measures for those selected 

sources and determines which are 

necessary to make reasonable progress. 

Those measures are then incorporated 

into the state’s long-term strategy. After 

a State has developed its long-term 

strategy, it then establishes RPGs for 

each Class I area within its borders by 

modeling the visibility impacts of all 

reasonable progress controls at the end 

of the second implementation period, 

i.e., in 2028, as well as the impacts of 

other requirements of the CAA. The 

RPGs include reasonable progress 

controls not only for sources in the State 

in which the Class I area is located, but 

also for sources in other states that 

contribute to visibility impairment in 

that area. The RPGs are then compared 

to the baseline visibility conditions and 

the URP to ensure that progress is being 

made towards the statutory goal of 

preventing any future and remedying 

any existing anthropogenic visibility 

impairment in Class I areas. 40 CFR 

51.308(f)(2)–(3). 

In addition to satisfying the 

requirements at 40 CFR 51.308(f) related 

to reasonable progress, the regional haze 

SIP revisions for the second 

implementation period must address the 

requirements in § 51.308(g)(1) through 

(5) pertaining to periodic reports 

describing progress towards the RPGs, 

40 CFR 51.308(f)(5), as well as 

requirements for FLM consultation that 

apply to all visibility protection SIPs 

and SIP revisions. 40 CFR 51.308(i). 

A State must submit its regional haze 

SIP and subsequent SIP revisions to the 

EPA according to the requirements 

applicable to all SIP revisions under the 

CAA and EPA’s regulations. See CAA 

169A(b)(2); CAA 110(a). Upon EPA 

approval, a SIP is enforceable by the 

Agency and the public under the CAA. 


khammond on DSKJM1Z7X2PROD with PROPOSALS2
83342 Federal Register / Vol. 89, No. 199 / Tuesday, October 15, 2024 / Proposed Rules 

18The 2018 Visibility Tracking Guidance 

references and relies on parts of the 2003 Tracking 

Guidance: ‘‘Guidance for Tracking Progress Under 

the Regional Haze Rule,’’ which can be found at 

https://www3.epa.gov/ttnamti1/files/ambient/ 

visible/tracking.pdf. 

19This notice also refers to the 20% clearest and 

20% most anthropogenically impaired days as the 

‘‘clearest’’ and ‘‘most impaired’’ or ‘‘most 

anthropogenically impaired’’ days, respectively. 

20The RHR at 40 CFR 51.308(f)(1)(ii) contains an 

error related to the requirement for calculating two 

sets of natural conditions values. The rule says 

‘‘most impaired days or the clearest days’’ where it 

should say ‘‘most impaired days and clearest days.’’ 

This is an error that was intended to be corrected 

in the 2017 RHR Revisions but did not get corrected 

in the final rule language. This is supported by the 

preamble text at 82 FR 3098: ‘‘In the final version 

of 40 CFR 51.308(f)(1)(ii), an occurrence of ‘‘or’’ has 

been corrected to ‘‘and’’ to indicate that natural 

visibility conditions for both the most impaired 

days and the clearest days must be based on 

available monitoring information.’’ 

21Being on or below the URP is not a ‘‘safe 

harbor’’; i.e., achieving the URP does not mean that 

a Class I area is making ‘‘reasonable progress’’ and 

does not relieve a state from using the four statutory 

factors to determine what level of control is needed 

to achieve such progress. See, e.g., 82 FR at 3093. 

If EPA finds that a State fails to make 

a required SIP revision, or if the EPA 

finds that a state’s SIP is incomplete or 

disapproves the SIP, the Agency must 

promulgate a federal implementation 

plan (FIP) that satisfies the applicable 

requirements. CAA 110(c)(1). 

A. Identification of Class I Areas 

The first step in developing a regional 

haze SIP is for a State to determine 

which Class I areas, in addition to those 

within its borders, ‘‘may be affected’’ by 

emissions from within the State. In the 

1999 RHR, the EPA determined that all 

states contribute to visibility 

impairment in at least one Class I area, 

64 FR at 35720–22, and explained that 

the statute and regulations lay out an 

‘‘extremely low triggering threshold’’ for 

determining ‘‘whether States should be 

required to engage in air quality 

planning and analysis as a prerequisite 

to determining the need for control of 

emissions from sources within their 

State.’’ Id. at 35721. 

A State must determine which Class 

I areas must be addressed by its SIP by 

evaluating the total emissions of 

visibility impairing pollutants from all 

sources within the State. While the RHR 

does not require this evaluation to be 

conducted in any particular manner, 

EPA’s 2019 Guidance provides 

recommendations for how such an 

assessment might be accomplished, 

including by, where appropriate, using 

the determinations previously made for 

the first implementation period. 2019 

Guidance at 8–9. In addition, the 

determination of which Class I areas 

may be affected by a state’s emissions is 

subject to the requirement in 40 CFR 

51.308(f)(2)(iii) to ‘‘document the 

technical basis, including modeling, 

monitoring, cost, engineering, and 

emissions information, on which the 

State is relying to determine the 

emission reduction measures that are 

necessary to make reasonable progress 

in each mandatory Class I Federal area 

it affects.’’ 

B. Calculations of Baseline, Current, 

and Natural Visibility Conditions; 

Progress to Date; and the Uniform Rate 

of Progress 

As part of assessing whether a SIP 

submission for the second 

implementation period is providing for 

reasonable progress towards the 

national visibility goal, the RHR 

contains requirements in § 51.308(f)(1) 

related to tracking visibility 

improvement over time. The 

requirements of this subsection apply 

only to states having Class I areas within 

their borders; the required calculations 

must be made for each such Class I area. 

EPA’s 2018 Visibility Tracking 

Guidance 18 provides recommendations 

to assist states in satisfying their 

obligations under § 51.308(f)(1); 

specifically, in developing information 

on baseline, current, and natural 

visibility conditions, and in making 

optional adjustments to the URP to 

account for the impacts of international 

anthropogenic emissions and prescribed 

fires. See 82 FR at 3103–05. 

The RHR requires tracking of 

visibility conditions on two sets of days: 

the clearest and the most impaired days. 

Visibility conditions for both sets of 

days are expressed as the average 

deciview index for the relevant five-year 

period (the period representing baseline 

or current visibility conditions). The 

RHR provides that the relevant sets of 

days for visibility tracking purposes are 

the 20% clearest (the 20% of monitored 

days in a calendar year with the lowest 

values of the deciview index) and 20% 

most impaired days (the 20% of 

monitored days in a calendar year with 

the highest amounts of anthropogenic 

visibility impairment).19 40 CFR 51.301. 

A State must calculate visibility 

conditions for both the 20% clearest and 

20% most impaired days for the 

baseline period of 2000–2004 and the 

most recent five-year period for which 

visibility monitoring data are available 

(representing current visibility 

conditions). 40 CFR 51.308(f)(1)(i), (iii). 

States must also calculate natural 

visibility conditions for the clearest and 

most impaired days,20 by estimating the 

conditions that would exist on those 

two sets of days absent anthropogenic 

visibility impairment. 40 CFR 

51.308(f)(1)(ii). Using all these data, 

states must then calculate, for each 

Class I area, the amount of progress 

made since the baseline period (2000– 

2004) and how much improvement is 

left to achieve to reach natural visibility 

conditions. 

Using the data for the set of most 

impaired days only, states must plot a 

line between visibility conditions in the 

baseline period and natural visibility 

conditions for each Class I area to 

determine the URP—the amount of 

visibility improvement, measured in 

deciviews, that would need to be 

achieved during each implementation 

period to achieve natural visibility 

conditions by the end of 2064. The URP 

is used in later steps of the reasonable 

progress analysis for informational 

purposes and to provide a nonenforceable benchmark against which to 

assess a Class I area’s rate of visibility 

improvement.21 Additionally, in the 

2017 RHR Revisions, the EPA provided 

states the option of proposing to adjust 

the endpoint of the URP to account for 

impacts of anthropogenic sources 

outside the United States and/or 

impacts of certain types of wildland 

prescribed fires. These adjustments, 

which must be approved by the EPA, 

are intended to avoid any perception 

that states should compensate for 

impacts from international 

anthropogenic sources and to give states 

the flexibility to determine that limiting 

the use of wildland-prescribed fire is 

not necessary for reasonable progress. 

82 FR 3107 footnote 116. 

The EPA’s 2018 Visibility Tracking 

Guidance can be used to help satisfy the 

40 CFR 51.308(f)(1) requirements, 

including in developing information on 

baseline, current, and natural visibility 

conditions, and in making optional 

adjustments to the URP. In addition, the 

2020 Data Completeness Memo provides 

recommendations on the data 

completeness language referenced in 

§ 51.308(f)(1)(i) and provides updated 

natural conditions estimates for each 

Class I area. 

C. Long-Term Strategy for Regional 

Haze 

The core component of a regional 

haze SIP submission is a long-term 

strategy that addresses regional haze in 

each Class I area within a state’s borders 

and each Class I area that may be 

affected by emissions from the State. 

The long-term strategy ‘‘must include 

the enforceable emissions limitations, 

compliance schedules, and other 

measures that are necessary to make 

reasonable progress, as determined 

pursuant to (f)(2)(i) through (iv).’’ 40 


khammond on DSKJM1Z7X2PROD with PROPOSALS2
Federal Register / Vol. 89, No. 199 / Tuesday, October 15, 2024 / Proposed Rules 83343 

22Similarly, in responding to comments on the 

2017 RHR Revisions the EPA explained that ‘‘[a] 

state should not fail to address its many relatively 

low-impact sources merely because it only has such 

sources and another state has even more low-impact 

sources and/or some high impact sources.’’ 

Responses to Comments on Protection of Visibility: 

Amendments to Requirements for State Plans; 

Proposed Rule (81 FR 26942, May 4, 2016) at 87– 

88. 

23The CAA provides that, ‘‘[i]n determining 

reasonable progress there shall be taken into 

consideration’’ the four statutory factors. CAA 

169A(g)(1). However, in addition to four-factor 

analyses for selected sources, groups of sources, or 

source categories, a state may also consider 

additional emission reduction measures for 

inclusion in its long-term strategy, e.g., from other 

newly adopted, on-the-books, or on-the-way rules 

and measures for sources not selected for four-factor 

analysis for the second planning period. 

24 ‘‘Each source’’ or ‘‘particular source’’ is used 

here as shorthand. While a source-specific analysis 

is one way of applying the four factors, neither the 

statute nor the RHR requires states to evaluate 

individual sources. Rather, states have ‘‘the 

flexibility to conduct four-factor analyses for 

specific sources, groups of sources or even entire 

source categories, depending on state policy 

preferences and the specific circumstances of each 

state.’’ 82 FR at 3088. However, not all approaches 

to grouping sources for four-factor analysis are 

necessarily reasonable; the reasonableness of 

grouping sources in any particular instance will 

depend on the circumstances and the manner in 

which grouping is conducted. If it is feasible to 

establish and enforce different requirements for 

sources or subgroups of sources, and if relevant 

factors can be quantified for those sources or 

subgroups, then states should make a separate 

reasonable progress determination for each source 

or subgroup. 2021 Clarifications Memo at 7–8. 

CFR 51.308(f)(2). The amount of 

progress that is ‘‘reasonable progress’’ is 

based on applying the four statutory 

factors in CAA section 169A(g)(1) in an 

evaluation of potential control options 

for sources of visibility impairing 

pollutants, which is referred to as a 

‘‘four-factor’’ analysis. The outcome of 

that analysis is the emission reduction 

measures that a particular source or 

group of sources needs to implement to 

make reasonable progress towards the 

national visibility goal. See 40 CFR 

51.308(f)(2)(i). Emission reduction 

measures that are necessary to make 

reasonable progress may be either new, 

additional control measures for a 

source, or they may be the existing 

emission reduction measures that a 

source is already implementing. See 

2019 Guidance at 43; 2021 Clarifications 

Memo at 8–10. Such 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). 

Section 51.308(f)(2)(i) provides the 

requirements for the four-factor 

analysis. The first step of this analysis 

entails selecting the sources to be 

evaluated for emission reduction 

measures; to this end, the RHR requires 

states to consider ‘‘major and minor 

stationary sources or groups of sources, 

mobile sources, and area sources’’ of 

visibility impairing pollutants for 

potential four-factor control analysis. 40 

CFR 51.308(f)(2)(i). A threshold 

question at this step is which visibility 

impairing pollutants will be analyzed. 

As EPA previously explained, 

consistent with the first implementation 

period, EPA generally expects that each 

State will analyze at least SO2 and NOX

in selecting sources and determining 

control measures. See 2019 Guidance at 

12; 2021 Clarifications Memo at 4. A 

State that chooses not to consider at 

least these two pollutants should 

demonstrate why such consideration 

would be unreasonable. 2021 

Clarifications Memo at 4. 

While states have the option to 

analyze all sources, the 2019 Guidance 

explains that ‘‘an analysis of control 

measures is not required for every 

source in each implementation period,’’ 

and that ‘‘[s]electing a set of sources for 

analysis of control measures in each 

implementation period is . . . 

consistent with the Regional Haze Rule, 

which 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. However, given that 

source selection is the basis of all 

subsequent control determinations, a 

reasonable source selection process 

‘‘should be designed and conducted to 

ensure that source selection results in a 

set of pollutants and sources the 

evaluation of which has the potential to 

meaningfully reduce their contributions 

to visibility impairment.’’ 2021 

Clarifications Memo at 3. 

EPA explained in the 2021 

Clarifications Memo that each State has 

an obligation to submit a long-term 

strategy that addresses the regional haze 

visibility impairment that results from 

emissions from within that State. Thus, 

source selection should focus on the instate contribution to visibility 

impairment and be designed to capture 

a meaningful portion of the state’s total 

contribution to visibility impairment in 

Class I areas. A State should not decline 

to select its largest in-state sources on 

the basis that there are even larger outof-state contributors. 2021 Clarifications 

Memo at 4.22

Thus, while states have discretion to 

choose any source selection 

methodology that is reasonable, 

whatever choices they make should be 

reasonably explained. To this end, 40 

CFR 51.308(f)(2)(i) requires that a state’s 

SIP submission include ‘‘a description 

of the criteria it used to determine 

which sources or groups of sources it 

evaluated.’’ The technical basis for 

source selection, which may include 

methods for quantifying potential 

visibility impacts such as emissions 

divided by distance metrics, trajectory 

analyses, residence time analyses, and/ 

or photochemical modeling, must also 

be appropriately documented, as 

required by 40 CFR 51.308(f)(2)(iii). 

Once a State has selected the set of 

sources, the next step is to determine 

the emissions reduction measures for 

those sources that are necessary to make 

reasonable progress for the second 

implementation period.23 This is 

accomplished by considering the four 

factors—‘‘the costs of compliance, the 

time necessary for compliance, and the 

energy and nonair quality 

environmental impacts of compliance, 

and the remaining useful life of any 

existing source subject to such 

requirements.’’ CAA 169A(g)(1). The 

EPA has explained that the four-factor 

analysis is an assessment of potential 

emission reduction measures (i.e., 

control options) for sources; ‘‘use of the 

terms ‘compliance’ and ‘subject to such 

requirements’ in section 169A(g)(1) 

strongly indicates that Congress 

intended the relevant determination to 

be the requirements with which sources 

would have to comply to satisfy the 

CAA’s reasonable progress mandate.’’ 82 

FR at 3091. Thus, for each source it has 

selected for four-factor analysis,24 a 

State must consider a ‘‘meaningful set’’ 

of technically feasible control options 

for reducing emissions of visibility 

impairing pollutants. Id. at 3088. The 

2019 Guidance provides that ‘‘[a] State 

must reasonably pick and justify the 

measures that it will consider, 

recognizing that there is no statutory or 

regulatory requirement to consider all 

technically feasible measures or any 

particular measures. A range of 

technically feasible measures available 

to reduce emissions would be one way 

to justify a reasonable set.’’ 2019 

Guidance at 29. 

EPA’s 2021 Clarifications Memo 

provides further guidance on what 

constitutes a reasonable set of control 

options for consideration: ‘‘A reasonable 

four-factor analysis will consider the 

full range of potentially reasonable 

options for reducing emissions.’’ 2021 

Clarifications Memo at 7. In addition to 

add-on controls and other retrofits (i.e., 

new emissions reduction measures for 

sources), EPA explained that states 

should generally analyze efficiency 

improvements for sources’ existing 

measures as control options in their 

four-factor analyses, as in many cases 

such improvements are reasonable given 

that they typically involve only 

additional operation and maintenance 


khammond on DSKJM1Z7X2PROD with PROPOSALS2
83344 Federal Register / Vol. 89, No. 199 / Tuesday, October 15, 2024 / Proposed Rules 

25See, e.g., Responses to Comments on Protection 

of Visibility: Amendments to Requirements for 

State Plans; Proposed Rule (81 FR 26942, May 4, 

2016) (December 2016), Docket Number EPA–HQ– 

OAR–2015–0531, U.S. Environmental Protection 

Agency at 186; 2019 Guidance at 36–37. 

26States may choose to, but are not required to, 

include measures in their long-term strategies 

beyond just the emission reduction measures that 

are necessary for reasonable progress. See 2021 

Clarifications Memo at 16. For example, states with 

smoke management programs may choose to submit 

their smoke management plans to the EPA for 

inclusion in their SIPs but are not required to do 

so. See, e.g., 82 FR at 3108–09 (requirement to 

consider smoke management practices and smoke 

management programs under 40 CFR 

51.308(f)(2)(iv) does not require states to adopt such 

practices or programs into their SIPs, although they 

may elect to do so). 

27See Arizona ex rel. Darwin v. U.S. EPA, 815 

F.3d 519, 531 (9th Cir. 2016); Nebraska v. U.S. EPA, 

812 F.3d 662, 668 (8th Cir. 2016); North Dakota v. 

EPA, 730 F.3d 750, 761 (8th Cir. 2013); Oklahoma 

v. EPA, 723 F.3d 1201, 1206, 1208–10 (10th Cir. 

2013); cf. also Nat’l Parks Conservation Ass’n v. 

EPA, 803 F.3d 151, 165 (3d Cir. 2015); Alaska Dep’t 

of Envtl. Conservation v. EPA, 540 U.S. 461, 485, 

490 (2004). 

costs. Additionally, the 2021 

Clarifications Memo provides that states 

that have assumed a higher emissions 

rate than a source has achieved or could 

potentially achieve using its existing 

measures should also consider lower 

emissions rates as potential control 

options. That is, a State should consider 

a source’s recent actual and projected 

emission rates to determine if it could 

reasonably attain lower emission rates 

with its existing measures. If so, the 

State should analyze the lower emission 

rate as a control option for reducing 

emissions. 2021 Clarifications Memo at 

7. The EPA’s recommendations to 

analyze potential efficiency 

improvements and achievable lower 

emission rates apply to both sources 

that have been selected for four-factor 

analysis and those that have forgone a 

four-factor analysis on the basis of 

existing ‘‘effective controls.’’ See 2021 

Clarifications Memo at 5, 10. 

After identifying a reasonable set of 

potential control options for the sources 

it has selected, a State then collects 

information on the four factors with 

regard to each option identified. The 

EPA has also explained that, in addition 

to the four statutory factors, states have 

flexibility under the CAA and RHR to 

reasonably consider visibility benefits as 

an additional factor alongside the four 

statutory factors.25 The 2019 Guidance 

provides recommendations for the types 

of information that can be used to 

characterize the four factors (with or 

without visibility), as well as ways in 

which states might reasonably consider 

and balance that information to 

determine which of the potential control 

options is necessary to make reasonable 

progress. See 2019 Guidance at 30–36. 

The 2021 Clarifications Memo contains 

further guidance on how states can 

reasonably consider modeled visibility 

impacts or benefits in the context of a 

four-factor analysis. 2021 Clarifications 

Memo at 12–13, 14–15. Specifically, the 

EPA explained that while visibility can 

reasonably be used when comparing 

and choosing between multiple 

reasonable control options, it should not 

be used to summarily reject controls 

that are reasonable given the four 

statutory factors. 2021 Clarifications 

Memo at 13. Ultimately, while states 

have discretion to reasonably weigh the 

factors and to determine what level of 

control is needed, § 51.308(f)(2)(i) 

provides that a State ‘‘must include in 

its implementation plan a description of 

. . . how the four factors were taken 

into consideration in selecting the 

measure for inclusion in its long-term 

strategy.’’ 

As explained above, § 51.308(f)(2)(i) 

requires states to determine the 

emission reduction measures for sources 

that are necessary to make reasonable 

progress by considering the four factors. 

Pursuant to § 51.308(f)(2), measures that 

are necessary to make reasonable 

progress towards the national visibility 

goal must be included in a state’s longterm strategy and in its SIP.26 If the 

outcome of a four-factor analysis is a 

new, additional emission reduction 

measure for a source, that new measure 

is necessary to make reasonable progress 

towards remedying existing 

anthropogenic visibility impairment and 

must be included in the SIP. If the 

outcome of a four-factor analysis is that 

no new measures are reasonable for a 

source, continued implementation of 

the source’s existing measures is 

generally necessary to prevent future 

emission increases and thus to make 

reasonable progress towards the second 

part of the national visibility goal: 

preventing future anthropogenic 

visibility impairment. See CAA 

169A(a)(1). That is, when the result of 

a four-factor analysis is that no new 

measures are necessary to make 

reasonable progress, the source’s 

existing measures are generally 

necessary to make reasonable progress 

and must be included in the SIP. 

However, there may be circumstances in 

which a State can demonstrate that a 

source’s existing measures are not 

necessary to make reasonable progress. 

Specifically, if a State can demonstrate 

that a source will continue to 

implement its existing measures and 

will not increase its emissions rate, it 

may not be necessary to have those 

measures in the long-term strategy to 

prevent future emissions increases and 

future visibility impairment. The EPA’s 

2021 Clarifications Memo provides 

further explanation and guidance on 

how states may demonstrate that a 

source’s existing measures are not 

necessary to make reasonable progress. 

See 2021 Clarifications Memo at 8–10. 

If the State can make such a 

demonstration, it need not include a 

source’s existing measures in the longterm strategy or its SIP. 

As with source selection, the 

characterization of information on each 

of the factors is also subject to the 

documentation requirement in 

§ 51.308(f)(2)(iii). The reasonable 

progress analysis, including source 

selection, information gathering, 

characterization of the four statutory 

factors (and potentially visibility), 

balancing of the four factors, and 

selection of the emission reduction 

measures that represent reasonable 

progress, is a technically complex 

exercise, but also a flexible one that 

provides states with bounded discretion 

to design and implement approaches 

appropriate to their circumstances. 

Given this flexibility, § 51.308(f)(2)(iii) 

plays an important function in requiring 

a State to document the technical basis 

for its decision making so that the 

public and the EPA can comprehend 

and evaluate the information and 

analysis the State relied upon to 

determine what emission reduction 

measures must be in place to make 

reasonable progress. The technical 

documentation must include the 

modeling, monitoring, cost, engineering, 

and emissions information on which the 

State relied to determine the measures 

necessary to make reasonable progress. 

This documentation requirement can be 

met through the provision of and 

reliance on technical analyses 

developed through a regional planning 

process, so long as that process and its 

output has been approved by all State 

participants. In addition to the explicit 

regulatory requirement to document the 

technical basis of their reasonable 

progress determinations, states are also 

subject to the general principle that 

those determinations must be 

reasonably moored to the statute.27 That 

is, a state’s decisions about the emission 

reduction measures that are necessary to 

make reasonable progress must be 

consistent with the statutory goal of 

remedying existing and preventing 

future visibility impairment. 

The four statutory factors (and 

potentially visibility) are used to 

determine what emission reduction 

measures for selected sources must be 

included in a state’s long-term strategy 


khammond on DSKJM1Z7X2PROD with PROPOSALS2
Federal Register / Vol. 89, No. 199 / Tuesday, October 15, 2024 / Proposed Rules 83345 

28The five ‘‘additional factors’’ for consideration 

in section 51.308(f)(2)(iv) are distinct from the four 

factors listed in CAA section 169A(g)(1) and 40 CFR 

51.308(f)(2)(i) that states must consider and apply 

to sources in determining reasonable progress. 

29RPGs are intended to reflect the projected 

impacts of the measures all contributing states 

include in their long-term strategies. However, due 

to the timing of analyses and of control 

determinations by other states, other on-going 

emissions changes, a particular state’s RPGs may 

not reflect all control measures and emissions 

reductions that are expected to occur by the end of 

the implementation period. The 2019 Guidance 

provides recommendations for addressing the 

timing of RPG calculations when states are 

developing their long-term strategies on disparate 

schedules, as well as for adjusting RPGs using a 

post-modeling approach. 2019 Guidance at 47–48. 

for making reasonable progress. 

Additionally, the RHR at 40 CFR 

51.3108(f)(2)(iv) separately provides five 

‘‘additional factors’’ 28 that states must 

consider in developing their long-term 

strategies: (1) Emission reductions due 

to ongoing air pollution control 

programs, including measures to 

address reasonably attributable visibility 

impairment; (2) measures to reduce the 

impacts of construction activities; (3) 

source retirement and replacement 

schedules; (4) basic smoke management 

practices for prescribed fire used for 

agricultural and wildland vegetation 

management purposes and smoke 

management programs; and (5) the 

anticipated net effect on visibility due to 

projected changes in point, area, and 

mobile source emissions over the period 

addressed by the long-term strategy. The 

2019 Guidance provides that a State 

may satisfy this requirement by 

considering these additional factors in 

the process of selecting sources for fourfactor analysis, when performing that 

analysis, or both, and that not every one 

of the additional factors needs to be 

considered at the same stage of the 

process. See 2019 Guidance at 21. The 

EPA provided further guidance on the 

five additional factors in the 2021 

Clarifications Memo, explaining that a 

State should generally not reject costeffective and otherwise reasonable 

controls merely because there have been 

emission reductions since the first 

planning period owing to other ongoing 

air pollution control programs or merely 

because visibility is otherwise projected 

to improve at Class I areas. 

Additionally, states generally should 

not rely on these additional factors to 

summarily assert that the State has 

already made sufficient progress and, 

therefore, no sources need to be selected 

or no new controls are needed 

regardless of the outcome of four-factor 

analyses. 2021 Clarifications Memo at 

13. 

Because the air pollution that causes 

regional haze crosses State boundaries, 

§ 51.308(f)(2)(ii) requires a State to 

consult with other states that also have 

emissions that are reasonably 

anticipated to contribute to visibility 

impairment in a given Class I area. 

Consultation allows for each State that 

impacts visibility in an area to share 

whatever technical information, 

analyses, and control determinations 

may be necessary to develop 

coordinated emission management 

strategies. This coordination may be 

managed through inter- and intra-RPO 

consultation and the development of 

regional emissions strategies; additional 

consultations between states outside of 

RPO processes may also occur. If a 

State, pursuant to consultation, agrees 

that certain measures (e.g., a certain 

emission limitation) are necessary to 

make reasonable progress at a Class I 

area, it must include those measures in 

its SIP. 40 CFR 51.308(f)(2)(ii)(A). 

Additionally, the RHR requires that 

states that contribute to visibility 

impairment at the same Class I area 

consider the emission reduction 

measures the other contributing states 

have identified as being necessary to 

make reasonable progress for their own 

sources. 40 CFR 51.308(f)(2)(ii)(B). If a 

State has been asked to consider or 

adopt certain emission reduction 

measures, but ultimately determines 

those measures are not necessary to 

make reasonable progress, that State 

must document in its SIP the actions 

taken to resolve the disagreement. 40 

CFR 51.308(f)(2)(ii)(C). The EPA will 

consider the technical information and 

explanations presented by the 

submitting State and the State with 

which it disagrees when considering 

whether to approve the state’s SIP. See 

Id.; 2019 Guidance at 53. Under all 

circumstances, a State must document 

in its SIP submission all substantive 

consultations with other contributing 

states. 40 CFR 51.308(f)(2)(ii)(C). 

D. Reasonable Progress Goals 

Reasonable progress goals ‘‘measure 

the progress that is projected to be 

achieved by the control measures states 

have determined are necessary to make 

reasonable progress based on a fourfactor analysis.’’ 82 FR at 3091. Their 

primary purpose is to assist the public 

and the EPA in assessing the 

reasonableness of states’ long-term 

strategies for making reasonable 

progress towards the national visibility 

goal. See 40 CFR 51.308(f)(3)(iii)–(iv). 

States in which Class I areas are located 

must establish two RPGs, both in 

deciviews—one representing visibility 

conditions on the clearest days and one 

representing visibility on the most 

anthropogenically impaired days—for 

each area within their borders. 40 CFR 

51.308(f)(3)(i). The two RPGs are 

intended to reflect the projected 

impacts, on the two sets of days, of the 

emission reduction measures the State 

with the Class I area, as well as all other 

contributing states, have included in 

their long-term strategies for the second 

implementation period.29 The RPGs also 

account for the projected impacts of 

implementing other CAA requirements, 

including non-SIP based requirements. 

Because RPGs are the modeled result of 

the measures in states’ long-term 

strategies (as well as other measures 

required under the CAA), they cannot 

be determined before states have 

conducted their four-factor analyses and 

determined the control measures that 

are necessary to make reasonable 

progress. See 2021 Clarifications Memo 

at 6. 

For the second implementation 

period, the RPGs are set for 2028. 

Reasonable progress goals are not 

enforceable targets, 40 CFR 

51.308(f)(3)(iii); rather, they ‘‘provide a 

way for the states to check the projected 

outcome of the [long-term strategy] 

against the goals for visibility 

improvement.’’ 2019 Guidance at 46. 

While states are not legally obligated to 

achieve the visibility conditions 

described in their RPGs, § 51.308(f)(3)(i) 

requires that ‘‘[t]he long-term strategy 

and the reasonable progress goals must 

provide for an improvement in visibility 

for the most impaired days since the 

baseline period and ensure no 

degradation in visibility for the clearest 

days since the baseline period.’’ Thus, 

states are required to have emission 

reduction measures in their long-term 

strategies that are projected to achieve 

visibility conditions on the most 

impaired days that are better than the 

baseline period and shows no 

degradation on the clearest days 

compared to the clearest days from the 

baseline period. The baseline period for 

the purpose of this comparison is the 

baseline visibility condition—the 

annual average visibility condition for 

the period 2000–2004. See 40 CFR 

51.308(f)(1)(i), 82 FR at 3097–98. 

So that RPGs may also serve as a 

metric for assessing the amount of 

progress a State is making towards the 

national visibility goal, the RHR 

requires states with Class I areas to 

compare the 2028 RPG for the most 

impaired days to the corresponding 

point on the URP line (representing 

visibility conditions in 2028 if visibility 


khammond on DSKJM1Z7X2PROD with PROPOSALS2
83346 Federal Register / Vol. 89, No. 199 / Tuesday, October 15, 2024 / Proposed Rules 

30See ‘‘Step 8: Additional requirements for 

regional haze SIPs’’ in 2019 Guidance at 55. 

31 Id. 

32The EPA’s visibility protection regulations 

define ‘‘reasonably attributable visibility 

impairment’’ as ‘‘visibility impairment that is 

caused by the emission of air pollutants from one, 

or a small number of sources.’’ 40 CFR 51.301. 

were to improve at a linear rate from 

conditions in the baseline period of 

2000–2004 to natural visibility 

conditions in 2064). If the most 

impaired days RPG in 2028 is above the 

URP (i.e., if visibility conditions are 

improving more slowly than the rate 

described by the URP), each State that 

contributes to visibility impairment in 

the Class I area must demonstrate, based 

on the four-factor analysis required 

under 40 CFR 51.308(f)(2)(i), that no 

additional emission reduction measures 

would be reasonable to include in its 

long-term strategy. 40 CFR 

51.308(f)(3)(ii). To this end, 40 CFR 

51.308(f)(3)(ii) requires that each State 

contributing to visibility impairment in 

a Class I area that is projected to 

improve more slowly than the URP 

provide ‘‘a robust demonstration, 

including documenting the criteria used 

to determine which sources or groups 

[of] sources were evaluated and how the 

four factors required by paragraph 

(f)(2)(i) were taken into consideration in 

selecting the measures for inclusion in 

its long-term strategy.’’ The 2019 

Guidance provides suggestions about 

how such a ‘‘robust demonstration’’ 

might be conducted. See 2019 Guidance 

at 50–51. 

The 2017 RHR, 2019 Guidance, and 

2021 Clarifications Memo also explain 

that projecting an RPG that is on or 

below the URP based on only on-thebooks and/or on-the-way control 

measures (i.e., control measures already 

required or anticipated before the fourfactor analysis is conducted) is not a 

‘‘safe harbor’’ from the CAA’s and RHR’s 

requirement that all states must conduct 

a four-factor analysis to determine what 

emission reduction measures constitute 

reasonable progress. The URP is a 

planning metric used to gauge the 

amount of progress made thus far and 

the amount left before reaching natural 

visibility conditions. However, the URP 

is not based on consideration of the four 

statutory factors and therefore cannot 

answer the question of whether the 

amount of progress being made in any 

particular implementation period is 

‘‘reasonable progress.’’ See 82 FR at 

3093, 3099–3100; 2019 Guidance at 22; 

2021 Clarifications Memo at 15–16. 

E. Monitoring Strategy and Other State 

Implementation Plan Requirements 

Section 51.308(f)(6) requires states to 

have certain strategies and elements in 

place for assessing and reporting on 

visibility. Individual requirements 

under this subsection apply either to 

states with Class I areas within their 

borders, states with no Class I areas but 

that are reasonably anticipated to cause 

or contribute to visibility impairment in 

any Class I area, or both. A State with 

Class I areas within its borders must 

submit with its SIP revision a 

monitoring strategy for measuring, 

characterizing, and reporting regional 

haze visibility impairment that is 

representative of all Class I areas within 

the State. SIP revisions for such states 

must also provide for the establishment 

of any additional monitoring sites or 

equipment needed to assess visibility 

conditions in Class I areas, as well as 

reporting of all visibility monitoring 

data to the EPA at least annually. 

Compliance with the monitoring 

strategy requirement may be met 

through a state’s participation in the 

Interagency Monitoring of Protected 

Visual Environments (IMPROVE) 

monitoring network, which is used to 

measure visibility impairment caused 

by air pollution at the 156 Class I areas 

covered by the visibility program. 40 

CFR 51.308(f)(6), (f)(6)(i), (f)(6)(iv). The 

IMPROVE monitoring data is used to 

determine the 20% most 

anthropogenically impaired and 20% 

clearest sets of days every year at each 

Class I area and tracks visibility 

impairment over time. 

All states’ SIPs must provide for 

procedures by which monitoring data 

and other information are used to 

determine the contribution of emissions 

from within the State to regional haze 

visibility impairment in affected Class I 

areas. 40 CFR 51.308(f)(6)(ii), (iii). 

Section 51.308(f)(6)(v) further requires 

that all states’ SIPs provide for a 

statewide inventory of emissions of 

pollutants that are reasonably 

anticipated to cause or contribute to 

visibility impairment in any Class I area; 

the inventory must include emissions 

for the most recent year for which data 

are available and estimates of future 

projected emissions. States must also 

include commitments to update their 

inventories periodically. The 

inventories themselves do not need to 

be included as elements in the SIP and 

are not subject to EPA review as part of 

the Agency’s evaluation of a SIP 

revision.30 All states’ SIPs must also 

provide for any other elements, 

including reporting, recordkeeping, and 

other measures, that are necessary for 

states to assess and report on visibility. 

40 CFR 51.308(f)(6)(vi). Per the 2019 

Guidance, a State may note in its 

regional haze SIP that its compliance 

with the Air Emissions Reporting Rule 

(AERR) in 40 CFR part 51 subpart A 

satisfies the requirement to provide for 

an emissions inventory for the most 

recent year for which data are available. 

To satisfy the requirement to provide 

estimates of future projected emissions, 

a State may explain in its SIP how 

projected emissions were developed for 

use in establishing RPGs for its own and 

nearby Class I areas.31

Separate from the requirements 

related to monitoring for regional haze 

purposes under 40 CFR 51.308(f)(6), the 

RHR also contains a requirement at 

§ 51.308(f)(4) related to any additional 

monitoring that may be needed to 

address visibility impairment in Class I 

areas from a single source or a small 

group of sources. This is called 

‘‘reasonably attributable visibility 

impairment.’’ 32 Under this provision, if 

the EPA or the FLM of an affected Class 

I area has advised a State that additional 

monitoring is needed to assess 

reasonably attributable visibility 

impairment, the State must include in 

its SIP revision for the second 

implementation period an appropriate 

strategy for evaluating such impairment. 

F. Requirements for Periodic Reports 

Describing Progress Towards the 

Reasonable Progress Goals 

Section 51.308(f)(5) requires a state’s 

regional haze SIP revision to address the 

requirements of paragraphs 40 CFR 

51.308(g)(1) through (5) so that the plan 

revision due in 2021 will serve also as 

a progress report addressing the period 

since submission of the progress report 

for the first implementation period. The 

regional haze progress report 

requirement is designed to inform the 

public and the EPA about a state’s 

implementation of its existing long-term 

strategy and whether such 

implementation is in fact resulting in 

the expected visibility improvement. 

See 81 FR 26942, 26950 (May 4, 2016); 

82 FR at 3119 (January 10, 2017). To this 

end, every state’s SIP revision for the 

second implementation period is 

required to describe the status of 

implementation of all measures 

included in the state’s long-term 

strategy, including BART and 

reasonable progress emission reduction 

measures from the first implementation 

period, and the resulting emissions 

reductions. 40 CFR 51.308(g)(1) and (2). 


khammond on DSKJM1Z7X2PROD with PROPOSALS2
Federal Register / Vol. 89, No. 199 / Tuesday, October 15, 2024 / Proposed Rules 83347 

33 77 FR 33642 (June 7, 2012). 34 79 FR 74818 (Dec. 16, 2014). 

35EME Homer City Generation, L.P v. EPA, 795 

F.3d 118 (D.C. Cir. 2015). 

36 81 FR 296 (Jan. 5, 2016). In July 2016, the 5th 

Circuit Court of Appeals issued a stay of the action. 

Texas v. EPA, 829 F.3d 405 (5th Cir. 2016). 

Subsequent to the stay opinion, the EPA requested 

and the court granted EPA’s motion for a partial 

voluntary remand. 

37See 82 FR 48324 (Oct. 17, 2017); 85 FR 49170 

(Aug. 12, 2020). 

38See 88 FR 28918 (May 4, 2023); 88 FR 48152 

(July 26, 2023). 

39EPA is not precluded from acting on a 

submitted second planning period SIP revision 

because reconsideration proceedings on first 

planning period actions remains ongoing. All states 

had an obligation to submit second planning period 

SIP revisions by July 31, 2021, regardless of the 

status of first planning period obligations. After a 

second planning period SIP revision is submitted to 

EPA for review, EPA is statutorily required to 

review and act on that plan within 12 months of 

the submittal being deemed complete. See CAA 

110(k)(1); 42 U.S.C. 7410(k)(1). Even with ongoing 

work on the second planning period, EPA will 

continue to work to address first planning period 

obligations. 

40The EPA has not yet taken action on the 

progress report SIP. 

A core component of the progress 

report requirements is an assessment of 

changes in visibility conditions on the 

clearest and most impaired days. For 

second implementation period progress 

reports, § 51.308(g)(3) requires states 

with Class I areas within their borders 

to first determine current visibility 

conditions for each area on the most 

impaired and clearest days, 40 CFR 

51.308(g)(3)(i)(B), and then to calculate 

the difference between those current 

conditions and baseline (2000–2004) 

visibility conditions to assess progress 

made to date. See 40 CFR 

51.308(g)(3)(ii)(B). States must also 

assess the changes in visibility 

impairment for the most impaired and 

clearest days since they submitted their 

first implementation period progress 

reports. See 40 CFR 51.308(g)(3)(iii)(B), 

(f)(5). Since different states submitted 

their first implementation period 

progress reports at different times, the 

starting point for this assessment will 

vary State by State. 

Similarly, states must provide 

analyses tracking the change in 

emissions of pollutants contributing to 

visibility impairment from all sources 

and activities within the State over the 

period since they submitted their first 

implementation period progress reports. 

See 40 CFR 51.308(g)(4), (f)(5). Changes 

in emissions should be identified by the 

type of source or activity. Section 

51.308(g)(5) also addresses changes in 

emissions since the period addressed by 

the previous progress report and 

requires states’ SIP revisions to include 

an assessment of any significant changes 

in anthropogenic emissions within or 

outside the State. This assessment must 

explain whether these changes in 

emissions were anticipated and whether 

they have limited or impeded progress 

in reducing emissions and improving 

visibility relative to what the State 

projected based on its long-term strategy 

for the first implementation period. 

G. Requirements for State and Federal 

Land Manager Coordination 

Clean Air Act section 169A(d) 

requires that before a State holds a 

public hearing on a proposed regional 

haze SIP revision, it must consult with 

the appropriate FLM or FLMs; pursuant 

to that consultation, the State must 

include a summary of the FLMs’ 

conclusions and recommendations in 

the notice to the public. Consistent with 

this statutory requirement, the RHR also 

requires that states ‘‘provide the [FLM] 

with an opportunity for consultation, in 

person and at a point early enough in 

the State’s policy analyses of its longterm strategy emission reduction 

obligation so that information and 

recommendations provided by the 

[FLM] can meaningfully inform the 

State’s decisions on the long-term 

strategy.’’ 40 CFR 51.308(i)(2). 

Consultation that occurs 120 days prior 

to any public hearing or public 

comment opportunity will be deemed 

‘‘early enough,’’ but the RHR provides 

that in any event the opportunity for 

consultation must be provided at least 

60 days before a public hearing or 

comment opportunity. This consultation 

must include the opportunity for the 

FLMs to discuss their assessment of 

visibility impairment in any Class I area 

and their recommendations on the 

development and implementation of 

strategies to address such impairment. 

40 CFR 51.308(i)(2). For the EPA to 

evaluate whether FLM consultation 

meeting the requirements of the RHR 

has occurred, the SIP submission should 

include documentation of the timing 

and content of such consultation. The 

SIP revision submitted to the EPA must 

also describe how the State addressed 

any comments provided by the FLMs. 

40 CFR 51.308(i)(3). Finally, a SIP 

revision must provide procedures for 

continuing consultation between the 

State and FLMs regarding the state’s 

visibility protection program, including 

development and review of SIP 

revisions, five-year progress reports, and 

the implementation of other programs 

having the potential to contribute to 

impairment of visibility in Class I areas. 

40 CFR 51.308(i)(4). 

IV. The EPA’s Evaluation of Texas’s 

Regional Haze Submission for the 

Second Implementation Period 

A. Background on Texas’s First 

Implementation Period SIP Submission 

Texas submitted its regional haze SIP 

for the first implementation period to 

the EPA on March 31, 2009. The EPA 

issued a limited disapproval of Texas’s 

RH SIP on June 7, 2012, due to its 

reliance on the Clean Air Interstate Rule 

(CAIR) to address BART requirements 

for Texas electric generating units 

(EGUs).33 The EPA proposed a rule to 

partially approve and partially 

disapprove Texas’s SIP on December 16, 

2014; 34 however, due to a related ruling 

from the United States Court of Appeals 

for the District of Columbia Circuit (D.C. 

Circuit),35 the EPA could not finalize 

the December 2014 proposal in its 

entirety. As such, the EPA’s obligations 

for the first implementation period for 

Texas’s regional haze SIP were 

addressed in two separate actions. One 

action, finalized on January 5, 2016, 

addressed the regional haze 

requirements in Texas except for BART 

requirements for EGUs.36 The second 

action, finalized on October 17, 2017, 

and affirmed on August 12, 2020, 

addressed BART requirements for Texas 

EGUs.37 The EPA has convened separate 

reconsideration proceedings for both 

actions.38 While these proceedings 

remain ongoing, they do not interfere 

with the EPA’s statutory obligation to 

take action on Texas’s SIP revision for 

the second implementation period.39

The requirements for regional haze 

SIPs for the first implementation period 

are contained in 40 CFR 51.308(d) and 

(e). Pursuant to 40 CFR 51.308(g), Texas 

was also responsible for submitting a 

five-year progress report as a SIP 

revision for the first implementation 

period, which it did in 2014.40

B. Texas’s Second Implementation 

Period SIP Submission and the EPA’s 

Evaluation 

In accordance with CAA sections 

169A and the RHR at 40 CFR 51.308(f) 

and (i), on July 20, 2021, Texas 

submitted a SIP revision to address its 

regional haze obligations for the second 

implementation period, which runs 

through 2028. Texas made its 2021 

Regional Haze SIP submission available 

for public comment on October 9, 2020. 

Texas received and responded to public 

comments and included the comments 

and responses to those comments in 

their submission. 

The following sections describe 

Texas’s RH SIP submission, Texas’s 

assessment of progress made since the 

first implementation period in reducing 

emissions of visibility impairing 

pollutants, and the visibility 

improvement progress at its Class I areas 


khammond on DSKJM1Z7X2PROD with PROPOSALS2
83348 Federal Register / Vol. 89, No. 199 / Tuesday, October 15, 2024 / Proposed Rules 

41 64 FR at 35721. 

42The EPA determined that ‘‘there is more than 

sufficient evidence to support our conclusion that 

emissions from each of the 48 contiguous States 

may reasonably be anticipated to cause or 

contribute to visibility impairment in a Class I 

area.’’ 64 FR at 35721. Hawaii, Alaska, and the U.S. 

Virgin Islands must also submit regional haze SIPs 

because they contain Class I areas. 

43 Id. 

44 Id. at 35722. 

45 Id. at 35721. 

46 Id. at 35722. 

47See 82 FR at 3094. 

48 2021 Texas Regional Haze Plan at 7–6. 

Extinction-weighted residence time is calculated 

from the time that a particular back-trajectory from 

a Class I area spent in the grid square containing 

the individual emission source of interest 

(residence time) weighted by the extinction 

coefficient for the visibility precursor (sulfate and 

nitrate). 

49For the purposes of the AOI analysis, Carlsbad 

Caverns was represented by data from the 

Guadalupe Mountains National Park monitor. See 

2021 Texas Regional Haze Plan at 1–5. 

and nearby Class I areas. This notice 

also contains EPA’s evaluation of 

Texas’s submission against the 

requirements of the CAA and RHR for 

the second implementation period of 

the regional haze program. 

C. Identification of Class I Areas 

Section 169A(b)(2) of the CAA 

requires each State in which any Class 

I area is located or ‘‘the emissions from 

which may reasonably be anticipated to 

cause or contribute to any impairment 

of visibility’’ in a Class I area to have a 

plan for making reasonable progress 

toward the national visibility goal. The 

RHR implements this statutory 

requirement at 40 CFR 51.308(f), which 

provides that each state’s plan ‘‘must 

address regional haze in 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,’’ and (f)(2), which 

requires each state’s plan to include a 

long-term strategy that addresses 

regional haze in such Class I areas. 

The EPA explained in the 1999 RHR 

preamble that the CAA section 

169A(b)(2) requirement that states 

submit SIPs to address visibility 

impairment establishes ‘‘an ‘extremely 

low triggering threshold’ in determining 

which States should submit SIPs for 

regional haze.’’ 41 In concluding that 

each of the contiguous 48 States and the 

District of Columbia meet this 

threshold,42 the EPA relied on ‘‘a large 

body of evidence demonstrat[ing] that 

long-range transport of fine PM 

contributes to regional haze,’’ 43

including modeling studies that 

‘‘preliminarily demonstrated that each 

State not having a Class I area had 

emissions contributing to impairment in 

at least one downwind Class I area.’’ 44

In addition to the technical evidence 

supporting a conclusion that each State 

contributes to existing visibility 

impairment, the EPA also explained that 

the second half of the national visibility 

goal—preventing future visibility 

impairment—requires having a 

framework in place to address future 

growth in visibility impairing emissions 

and makes it inappropriate to ‘‘establish 

criteria for excluding States or 

geographic areas from consideration as 

potential contributors to regional haze 

visibility impairment.’’ 45 Thus, the EPA 

concluded that the agency’s ‘‘statutory 

authority and the scientific evidence are 

sufficient to require all States to develop 

regional haze SIPs to ensure the 

prevention of any future impairment of 

visibility, and to conduct further 

analyses to determine whether 

additional control measures are needed 

to ensure reasonable progress in 

remedying existing impairment in 

downwind Class I areas.’’ 46 The EPA’s 

2017 revisions to the RHR did not 

disturb this conclusion.47

1. Texas Class I Areas 

Texas has two mandatory Class I areas 

within its borders, both of which are 

located in west Texas. Big Bend 

National Park (Big Bend) is in Brewster 

County and borders the Rio Grande and 

Mexico. Guadalupe Mountains National 

Park (Guadalupe Mountains) is in 

Culberson County and borders New 

Mexico. Both are managed by the 

National Park Service. 

Big Bend was authorized as a national 

park on June 20, 1935, and established 

and signed into law on June 12, 1944, 

as the nation’s 27th national park. Big 

Bend encompasses an area of 801,163 

acres, entirely within Brewster County, 

Texas. For more than 1,000 miles, the 

Rio Grande forms the boundary between 

Mexico and the U.S., with Big Bend 

administering approximately 118 miles 

along the international boundary. The 

park gets its name from the course of the 

Rio Grande, which makes a great bend 

from a southeasterly to northerly 

direction in the western portion of 

Texas. Big Bend has national 

significance as the largest protected area 

of Chihuahuan Desert in the continental 

U.S. The park contains river, desert, and 

mountain environments. 

Guadalupe Mountains was 

established as a national park on 

September 30, 1972, and contains 

Guadalupe Peak, the highest point in 

Texas at 8,749 feet, and El Capitan, a 

1,000 foot-high limestone cliff. 

Guadalupe Mountains are also part of a 

mostly buried 400-mile long U-shaped 

fossil reef complex, Capitan Reef. The 

park covers more than 86,000 acres and 

is in the same mountain range of 

Carlsbad Caverns National Park, which 

is located about 40 miles to the 

northeast in New Mexico. Guadalupe 

Mountains is also located in the 

Chihuahuan Desert. The park is 

surrounded by the South Plains to the 

east and north, Delaware Mountains to 

the south, and Sacramento Mountains to 

the west. 

2. Identification of Impacted Class I 

Areas Outside the State 

In addition to the two Class I areas in 

Texas, the TCEQ conducted area of 

influence analyses (AOIs) paired with 

emissions-over-distance (Q/d) analyses 

for 11 Class I areas in other states 

including Louisiana, Arkansas, 

Colorado, Missouri, Oklahoma, and 

New Mexico. The AOIs were generated 

using ammonium sulfate and 

ammonium nitrate extinction-weighted 

residence times (EWRT).48 The Class I 

areas included in the analysis from 

Texas and neighboring states are 

presented in table 1, which is taken 

from table 7–3: Class I Areas included 

in AOI Analyses of the 2021 Texas 

Regional Haze Plan.49

TABLE 1—CLASS I AREAS INCLUDED IN AOI ANALYSES OF THE 2021 TEXAS REGIONAL HAZE PLAN

Site Code State County Latitude Longitude 

Big Bend National Park .................................................... BIBE1 ........................................... TX 48043 29.3027 ¥103.178 

Breton Island .................................................................... BRIS1 .......................................... LA 22075 30.10863 ¥89.76168 

Caney Creek .................................................................... CACR1 ......................................... AR 05113 34.4544 ¥94.1429 

Great Sand Dunes ........................................................... GRSA1 ......................................... CO 08003 37.7249 ¥105.5185 

Guadalupe Mountains National Park ............................... GUMO .......................................... TX 48109 31.833 ¥104.8094 

Hercules-Glades ............................................................... HEG1 ........................................... MO 29213 36.6138 ¥92.9221 

Mingo ................................................................................ MING1 ......................................... MO 29207 36.9717 ¥90.1432 


khammond on DSKJM1Z7X2PROD with PROPOSALS2
Federal Register / Vol. 89, No. 199 / Tuesday, October 15, 2024 / Proposed Rules 83349 

50 64 FR at 35721. 

51 2019 Guidance at 8. 

52Texas also did not conduct an AOI analysis for 

the Bandelier Class I area for the same reasons 

provided for Bosque del Apache. 

53 2021 Texas Regional Haze Plan, appendix A at 

19 of 227; 2021 Texas Regional Haze Plan, Response 

to Comments at 460 of 653. 

54Comprehensive Air quality Model with 

extensions (CAMx) Particulate Source 

Apportionment Technique (PSAT). CAMx PSAT is 

capable of tracking source category emissions and 

separate source regions for certain PM species and 

precursor emissions. We discuss this further in the 

Technical Support Document (TSD) for this action, 

included in the docket. 

55 2021 Texas Regional Haze Plan, appendix A at 

26 of 227. 

56See 2021 Texas Regional Haze Plan, table 8–41 

at 8–53; and 2021 Texas Regional Haze Plan, 

appendix F at F–59 to F–61. 

57 2021 Texas Regional Haze Plan, appendix F at 

F–36. 

58 40 CFR 51.308(f)(1)(vi)(B). 

59See 2021 Texas Regional Haze Plan at 4–4. 

60https://views.cira.colostate.edu/fed/. See also 

2020 Data Completeness Memo, table 1. 

TABLE 1—CLASS I AREAS INCLUDED IN AOI ANALYSES OF THE 2021 TEXAS REGIONAL HAZE PLAN—Continued 

Site Code State County Latitude Longitude 

Rocky Mountain National Park ........................................ ROMO1 ........................................ CO 08069 40.2783 ¥105.5457 

Salt Creek ........................................................................ SACR1 ......................................... NM 35005 33.4598 ¥104.4042 

Upper Buffalo Wilderness ................................................ UPBO1 ......................................... AR 05101 35.8258 ¥93.203 

Wheeler Peak ................................................................... WHPE1 ........................................ NM 35055 36.5854 ¥105.42 

White Mountain ................................................................ WHIT1 .......................................... NM 35027 33.4687 ¥105.5349 

Wichita Mountains ............................................................ WIMO1 ......................................... OK 40031 34.7323 ¥98.713 

As explained above, the EPA 

concluded in the 1999 RHR that ‘‘all 

[s]tates contain sources whose 

emissions are reasonably anticipated to 

contribute to regional haze in a Class I 

area,’’ and this determination was not 

changed in the 2017 RHR.50 Critically, 

the statute and regulation both require 

that the cause-or-contribute assessment 

consider all emissions of visibility 

impairing pollutants from a State, as 

opposed to emissions of a particular 

pollutant or emissions from a certain set 

of sources. Consistent with these 

requirements, the 2019 Guidance makes 

it clear that ‘‘all types of anthropogenic 

sources are to be included in the 

determination’’ of whether a state’s 

emissions are reasonably anticipated to 

result in any visibility impairment.51

While Texas identified Class I areas 

within and outside of the State that are 

potentially impacted by Texas sources, 

Texas did not conduct an AOI analysis 

for the Bosque del Apache Class I area.52

Texas justifies this decision based on 

‘‘past SIP and FIP documentation’’ but 

provides no additional context or 

explanation of why that decision 

remains appropriate for this planning 

period.53 In contrast, Texas’s CAMx 

PSAT54 modeling identified Bosque del 

Apache as having impacts from Texas 

sources. According to Texas’s PSAT 

modeling, Texas sources contribute over 

seven percent of the total visibility 

impairment at Bosque del Apache.55

Specifically, the 2021 Texas Regional 

Haze Plan identifies that the influence 

due to particulate sulfate from Texas 

sources is more than five times the 

influence of New Mexico sources, and 

the influence due to particulate nitrate 

from Texas sources is nearly twice the 

influence of New Mexico sources.56

Thus, Texas’s PSAT modeling suggests 

that emissions from Texas sources are 

reasonably anticipated to contribute to 

visibility impairment at the Bosque del 

Apache Class I area given the low 

threshold for visibility impact on Class 

I areas discussed previously.57

Therefore, Texas did not complete its 

obligation under 40 CFR 51.308(f), 

which provides that each state’s plan 

‘‘must address regional haze in 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,’’ and (f)(2), which 

requires each state’s plan to include a 

long-term strategy that addresses 

regional haze in such Class I areas. 

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.58

In Chapter 4 of the 2021 Texas 

Regional Haze Plan, Texas determines 

and presents the baseline, natural, and 

current visibility conditions for both the 

20 percent most anthropogenically 

impaired days and the 20 percent 

clearest days for the State’s two Class I 

Areas consistent with the EPA’s RHR 

and guidance. In the 2021 Texas 

Regional Haze Plan, the TCEQ used 

visibility data from IMPROVE 

monitoring sites to calculate baseline 

visibility conditions. Consistent with 

the RHR, Texas calculated baseline 

visibility based on data from 2000–2004. 

For Big Bend specifically, baseline 

visibility conditions are based on valid 

data for 2001 through 2004 because 

2000 did not meet completeness 

criteria.59 Baseline visibility indices for 

Big Bend and Guadalupe Mountains are 

presented in the 2021 Texas Regional 

Haze Plan in table 4–4. In our review, 

we identified that the information 

provided by Texas in Chapter 4 of its 

2021 Regional Haze Plan as to the 

baseline and current conditions on the 

20 percent clearest days is inconsistent 

with the IMPROVE monitoring data and 

information presented in Chapter 8. 

Based on the information in table 8–42 

of the 2021 Regional Haze Plan, Texas 

identifies the correct data set for where 

this information is located but presents 

the incorrect data in Chapter 4. Based 

on the data source that Texas identified 

in Chapter 8, we present information in 

tables 2 and 4 consistent with 

information in Chapter 8 of its Plan and 

the IMPROVE monitoring data.60


khammond on DSKJM1Z7X2PROD with PROPOSALS2
83350 Federal Register / Vol. 89, No. 199 / Tuesday, October 15, 2024 / Proposed Rules 

61Marc Pitchford et al., Revised Algorithm for 

Estimating Light Extinction from IMPROVE Particle 

Speciation Data, j. Air & waste mgmt. Ass’n 1326, 

1326–1336 (2007), https://doi.org/10.3155/1047- 

3289.57.11.1326. 

62Availability of Modeling Data and Associated 

Technical Support Document for the EPA’s 

Updated 2028 Visibility Air Quality Modeling. 

https://www.epa.gov/visibility/technical-supportdocument-epas-updated-2028-regional-hazemodeling. The EPA Office of Air Quality Planning 

and Standards, Research Triangle Park (Sep. 19, 

2019). 

TABLE 2—ESTIMATE OF BASELINE VISIBILITY CONDITIONS (2000–2004) FOR CLASS I AREAS IN TEXAS

Class I area Most impaired haze index 

(dv) 

Clearest haze index 

(dv) 

Big Bend ............................................................................................................................ 15.57 5.78 

Guadalupe Mountains ........................................................................................................ 14.60 5.92 

Using the revised IMPROVE 

algorithm 61 and the methodology 

described in the 2018 Visibility 

Tracking Guidance, the TCEQ 

determined natural visibility conditions 

for Big Bend and Guadalupe Mountains, 

presented in table 4–3 of the 2021 Texas 

Regional Haze Plan, and included in the 

following table 3. 

TABLE 3—ESTIMATE OF NATURAL VISIBILITY CONDITIONS FOR CLASS I AREAS IN TEXAS

Class I area Most impaired haze index 

(dv) 

Clearest haze index 

(dv) 

Big Bend ............................................................................................................................ 5.33 1.62 

Guadalupe Mountains ........................................................................................................ 4.83 0.99 

The current visibility conditions, 

which are based on 2014–2018 

monitoring data, are presented in the 

2021 Texas Regional Haze Plan in table 

4–5 with corrected values included in 

the following table 4. 

TABLE 4—ESTIMATE OF CURRENT VISIBILITY CONDITIONS (2014–2018) FOR CLASS I AREAS IN TEXAS

Class I area Most impaired haze index 

(dv) 

Clearest haze index 

(dv) 

Big Bend ............................................................................................................................ 14.06 5.17 

Guadalupe Mountains ........................................................................................................ 12.64 4.73 

While the 2021 Texas Regional Haze 

Plan does not specifically present the 

differences between current visibility 

conditions and natural visibility 

conditions as well as the progress to 

date, we include these calculations 

using the corrected information in tables 

5 and 6. 

TABLE 5—PROGRESS TO DATE

(DIFFERENCES BETWEEN BASELINE AND CURRENT CONDITIONS) 

Class I area Most impaired 

(dv) 

Clearest haze 

(dv) 

Big Bend ............................................................................................................................ 1.51 0.61 

Guadalupe Mountains ........................................................................................................ 1.96 1.19 

TABLE 6—DIFFERENCES BETWEEN CURRENT AND NATURAL CONDITIONS

Class I area Most impaired 

(dv) 

Clearest haze 

(dv) 

Big Bend ............................................................................................................................ 8.73 3.55 

Guadalupe Mountains ........................................................................................................ 7.81 3.74 

The Regional Haze Rule allows states 

the option to adjust the 2064 glidepath 

endpoint to account for both 

international anthropogenic and certain 

prescribed fire impacts at Class I areas. 

In the EPA’s September 2019 

Availability of Modeling Data and 

Associated Technical Support 

Document for the EPA’s Updated 2028 

Visibility Air Quality Modeling 

memorandum 62 (EPA 2019 Modeling 

TSD), the EPA used 2028 modeling 

results to quantify the international and 

prescribed fire impacts at Class I areas 

on the 20% most anthropogenically 

impaired days. Texas used its own 

CAMx modeling results to adjust the 

URP to account for international 

anthropogenic emissions consistent 

with the approach used by the EPA in 

the TSD associated with the EPA’s 

Updated 2028 Visibility Air Quality 

Modeling memorandum. Texas’s 

adjusted URP for Big Bend and 

Guadalupe Mountains are presented in 

Figures 8–28 and 8–29 of its 2021 Texas 


khammond on DSKJM1Z7X2PROD with PROPOSALS2
Federal Register / Vol. 89, No. 199 / Tuesday, October 15, 2024 / Proposed Rules 83351 

63After Texas adjusted the glidepath endpoint to 

account for contributions from international 

anthropogenic emissions, one site (Salt Creek, NM) 

was projected to be above the adjusted URP. The 

EPA 2019 Modeling TSD also had Salt Creek above 

the adjusted glidepath. 64 2021 Texas Regional Haze Plan, table 8–43 at 

8–59 and table 8–46 at 8–67. 

65EPA 2019 Modeling TSD at 54, 56, and table 

5–2 at 59. 

66CAA 169A(b)(2)(B). 

67 40 CFR 51.308(f)(2)(i). 

68 40 CFR 51.308(f)(2). 

69 40 CFR 51.308(f)(2)(i), (iii). 

70See also CAA 169A(g)(1). 

71 2021 Texas Regional Haze Plan at 7–3. 

72As discussed previously in section IV.C., the 

monitor for Guadalupe Mountains also serves as the 

monitor for Carlsbad Caverns in New Mexico. 

73To calculate the Q/d for point sources, the 

TCEQ used 2028 projected emissions (Q in tons per 

year) and distance from the Class I area monitor to 

the source (d in kilometers). For non-EGUs, Texas 

estimated 2028 future year emissions from 2016 

reported emissions from the State of Texas Air 

Reporting System (STARS) coupled with growth 

factors developed by the consulting firm, Eastern 

Research Group, Inc. (ERG) See 2021 Texas 

Regional Haze Plan at 7–9. For EGUs, the TCEQ 

used data from the Eastern Regional Technical 

Advisory Committee (ERTAC) to estimate EGU 

projections for 2028. See 2021 Texas Regional Haze 

Plan at 7–9. 

74See 2021 Texas Regional Haze Plan, Figure 7– 

1 at 7–4 and Figure 7–2 at 7–5. Texas stated that 

those additional AOIs not represented in those 

figures in the SIP did not add additional sources for 

consideration. 2021 Texas Regional Haze Plan at 7– 

6. 

75See Texas 2021 Regional Haze Plan at 7–5 to 

7–6. Presented Class I areas are: Caney Creek, 

Guadalupe Mountains, Salt Creek, and Wichita 

Mountains for the NOX analysis, and Caney Creek, 

Guadalupe Mountains, and Wichita Mountains for 

the SO2 analysis. 

Regional Haze Plan.63 Texas’s adjusted 

URP in 2028 on the 20% most impaired 

visibility days is 14.38 deciviews for Big 

Bend and 12.81 for Guadalupe 

Mountains.64 These values for Big Bend 

and Guadalupe Mountains are within 

the range of 2028 adjusted glidepath 

values provided for in the EPA 2019 

Modeling TSD.65

The EPA finds that the visibility 

condition calculations for the two Texas 

Class I Areas meet the requirements of 

40 CFR 51.308(f)(1). Therefore, the EPA 

proposes to approve the portions of the 

2021 Texas Regional Haze Plan relating 

to 40 CFR 51.308(f)(1). 

E. Long-Term Strategy for Regional Haze 

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.66 As explained 

in the Background section of this notice, 

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.67 Each state’s long-term 

strategy must include the enforceable 

emission limitations, compliance 

schedules, and other measures that are 

necessary to make reasonable 

progress.68 All new (i.e., additional) 

measures that are the outcome of fourfactor 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.69

1. Source Selection 

a. Overview of Texas’s Source Selection 

Under 40 CFR 51.308(f)(2)(i), states 

must evaluate and determine the 

emission reduction measures that are 

necessary to make reasonable progress 

by considering the costs of compliance, 

the time necessary for compliance, the 

energy and non-air quality 

environmental impacts of compliance, 

and the remaining useful life of any 

potentially affected anthropogenic 

source of visibility impairment.70 In 

doing so, states should consider 

evaluating major and minor stationary 

sources or groups of sources, mobile 

sources, and area sources as part of their 

long-term strategy for regional haze. 

Furthermore, 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. 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 40 CFR 51.308(f)(2). Texas, 

however, conducted its own analysis 

separate from CenSARA’s analysis to 

select sources for further evaluation 

using the four statutory factors. 

Texas focused on sources of NOX and 

SO2 emissions in its control strategy 

analysis for the second planning period. 

Texas explained these are the main 

anthropogenic pollutants that affect 

visibility at Class I areas in Texas and 

Class I areas in neighboring states. Texas 

further stated that, ‘‘on an individual 

basis, point sources are the largest 

contributors to SO2 and NOX,’’ and thus 

Texas elected to focus on point sources 

in this planning period.71

Texas’s source selection methodology 

relied on a two-step approach. As the 

first step for source selection, Texas 

developed areas of influence (AOIs) for 

thirteen 72 Class I areas (in Texas and 

nearby states) to identify areas that may 

contain sources of NOX and SO2 that 

were expected to contribute to visibility 

impairment at these areas. The AOIs are 

graphical representations of the 

extinction weighted residence time 

(EWRT), which combines air flow 

patterns with ammonium sulfate and 

ammonium nitrate extinction measured 

at IMPROVE monitors at the Class I 

areas on the 20% most impaired days. 

The TCEQ used the AOI of a Class I area 

as a brightline cutoff to define the 

boundaries within which to further 

evaluate sources located within that 

area. As the second step, Texas then 

applied a Q/d threshold for NOX and for 

SO2 of greater than or equal to five to 

point sources located within the 

geographical area of the selected AOI 

threshold.73 As a result, any source 

within the AOI boundaries with a Q/d 

less than five or any source, regardless 

of its Q/d, that fell outside of the AOI 

boundaries were eliminated from 

further consideration. 

Although Texas determined AOIs for 

13 Class I areas in Texas and nearby 

states, Texas’s 2021 Regional Haze Plan 

focused only on those Class I areas 

where sources with a Q/d greater than 

or equal to five fell within the AOI 

boundary.74 Following this 

methodology, Texas selected 18 sources 

for further analysis for only four Class 

I areas: Wichita Mountains, Caney 

Creek, Guadalupe Mountains, and Salt 

Creek.75


khammond on DSKJM1Z7X2PROD with PROPOSALS2
83352 Federal Register / Vol. 89, No. 199 / Tuesday, October 15, 2024 / Proposed Rules 

76Texas 2021 Regional Haze Plan, table 7–5. 

77See 40 CFR 51.308(f)(2); CAA 169A(g)(1). 

78 2019 Guidance at 9, 13. The 2019 Guidance 

explains that in selecting sources, states must 

reasonably choose factors and apply them in a 

reasonable way given the statutory requirement to 

make reasonable progress towards national goal of 

preventing future and remedying existing 

anthropogenic visibility impairment). See CAA 

169A(b)(2). To that end, the 2019 Guidance 

recommends that states provide a detailed 

description of how the state used technical 

information to select a reasonable set of sources for 

an analysis of control measures including the basis 

for the visibility impact thresholds the state used 

(if applicable), and any other relevant information. 

See also 2021 Clarifications Memo at 3 (‘‘States 

cannot reasonably determine that they are making 

reasonable progress if they have not adequately 

considered the contributors to visibility 

impairment. Thus, while states have discretion to 

reasonably select sources, this analysis should be 

designed and conducted to ensure that source 

selection results in a set of pollutants and sources 

the evaluation of which has the potential to 

meaningfully reduce their contributions to visibility 

impairment.’’). 79 2021 Texas Regional Haze Plan at 7–7. 

TABLE 7—TEXAS’s SOURCE SELECTION FOR ITS 2021 REGIONAL HAZE PLAN 76

Company/site name Unit(s) Class I area(s) Pollutant(s) 

Coleto Creek Power/Coleto Creek Power 

Station.

(1) coal boiler ............................................... Wichita Mountains ...................... SO2. 

Southwestern Electric Power/Welsh Power 

Plant.

(2) coal boilers .............................................. Caney Creek & Wichita Mountains.SO2. 

AEP/Pirkey Power Plant ............................... (1) coal boiler ............................................... Caney Creek & Wichita Mountains.SO2. 

NRG Energy/Limestone Electric Generating 

Station.

(2) coal boilers .............................................. Wichita Mountains ...................... SO2. 

Vistra Energy/Martin Lake Electric Station ... (3) coal boilers .............................................. Caney Creek & Wichita Mountains.SO2. 

San Miguel Electric Cooperative/San Miguel 

Elec. Plant.

(1) coal boiler ............................................... Guadalupe Mountains & Wichita 

Mountains.

SO2. 

Public Service Co. of Oklahoma/Oklaunion 

Power Station.

(1) coal boiler ............................................... Wichita Mountains ...................... SO2 & NOX. 

Vistra Energy/Oak Grove Steam Electric 

Station.

(2) coal boilers .............................................. Wichita Mountains ...................... SO2. 

Holcim Texas LP/Midlothian Plant ............... (2) cement kilns ............................................ Wichita Mountains ...................... SO2. 

Vitro Flat Glass/Works No. 4 Wichita Falls 

Plant.

(2) glass melting furnaces ............................ Wichita Mountains ...................... SO2 & NOX. 

Graphic Packaging International/Texarkana 

Mill.

(4) boilers: (2) black liquor solids & NG; (1) 

NG & fuel oil; (1) NG, fuel oil, & other 

materials.

Caney Creek ............................... NOX. 

El Paso Natural Gas Co./Keystone Compressor Station.(15) reciprocating engines ............................ Guadalupe Mountains & Salt 

Creek.

NOX. 

El Paso Natural Gas Co./Cornudas Plant .... (6) turbines ................................................... Guadalupe Mountains ................ NOX. 

El Paso Natural Gas Co./Guadalupe Compressor Station.(1) turbine ..................................................... Guadalupe Mountains ................ NOX. 

GCC Permian/Odessa Cement Plant ........... (2) cement kilns ............................................ Guadalupe Mountains ................ NOX. 

Orion Engineered Carbons/Orange Carbon 

Black Plant.

(1) incinerator; (4) dryers; (2) tail gas and 

NG boilers; (1) flare.

Caney Creek ............................... SO2. 

Oxbow Calcining/Oxbow Calcining-Port Arthur.(4) coke calcining kilns ................................. Caney Creek ............................... SO2. 

Trinity Lightweight Aggregate (TRNLWS)/ 

Streetman Plant.

(1) lightweight aggregate kiln ....................... Wichita Mountains ...................... SO2. 

b. EPA’s Evaluation of Texas’s Source 

Selection Methodology 

In identifying the required emission 

limits, schedules of compliance, and 

other measures as may be necessary to 

make reasonable progress toward 

meeting the national goal, States first 

select sources for consideration of the 

four statutory factors.77 Under the RHR, 

States have flexibility in conducting 

their source selection; however, Texas’s 

source selection methodology was 

neither well-reasoned nor adequately 

justified.78 Notably, Texas did not select 

any sources for further analysis of 

control measures that may be necessary 

for inclusion as part of the long-term 

strategy to make reasonable progress for 

Big Bend National Park and did not 

select any SO2 sources for consideration 

for Salt Creek. Moreover, the EPA finds 

the source selection methodology used 

by Texas was not adequately or 

accurately described. As such, the 

threshold Texas applied to define its 

AOIs was not justified. Without the 

proper justification, it is unclear how, 

despite these deficiencies, Texas makes 

reasonable progress at these Class I 

areas. 

i. The TCEQ Failed To Adequately 

Describe the Criteria It Used To Select 

Sources 

Under 40 CFR 51.308(f)(2)(i), States 

are required to include a ‘‘description of 

the criteria it used to determine which 

sources or groups of sources it 

evaluated.’’ Based on our review of the 

2021 Texas Regional Haze Plan, the 

methodology Texas described in its SIP 

to develop its AOIs is inconsistent with, 

and would not result in, the AOIs 

presented in Texas’s SIP. Texas states in 

its SIP that the AOIs were determined 

by dividing the EWRT for each cell by 

the sum total of all the EWRTs (i.e., 

EWRT for each cell) across the entire 

domain.79 However, based on the 

documentation the EPA obtained during 

early engagement in the Fall of 2020 and 

comparing it to what was in its 2021 

Regional Haze Plan, Texas actually 

divided the EWRT for each cell by the 

maximum EWRT in the domain for each 

respective pollutant. There was thus an 

inconsistency between what Texas said 

its methodology was, and what was in 

its 2021 Regional Haze Plan submission. 

Specifically, in the 2020 early 

engagement document, Texas stated, 

‘‘. . . prior to plotting the AOIs, the 

weighted probabilities were scaled to 1 

by dividing the weighted probabilities 

in each cell by the maximum value in 


khammond on DSKJM1Z7X2PROD with PROPOSALS2
Federal Register / Vol. 89, No. 199 / Tuesday, October 15, 2024 / Proposed Rules 83353 

80See ‘‘README.AOIdevelopmentFor

2021RHSIP_Response_to_EPArequest.20Nov2020

update.docx’’ available in the docket for this action. 81Texas discusses its AOI and Q/d analysis in 

section 7.2.1 of its 2021 Texas Regional Haze Plan. 

82The 2019 Guidance describes a source selection 

approach utilizing residence time analysis that 

selects sources for further analysis by giving each 

point source a score that takes into account the 

source’s emissions, the daily values of light 

extinction at a Class I area, the distance between the 

source and a Class I area, and the relative frequency 

with which wind trajectories indicate that each 

source is upwind of the IMPROVE monitoring site. 

2019 Guidance at 13. This is the general approach 

followed by CenSARA and WRAP. 

83Texas found that on an individual basis point 

sources are the largest contributors to visibility 

impairment in Class I areas. 2021 Texas Regional 

Haze Plan at 7–3. 

84See 2021 Texas Regional Haze Plan, Figure 7– 

2 at 7–5; AOI for Big Bend located in Texas’s EWRT 

AMDA spreadsheet on TCEQ’s AMDA website at 

https://www.tceq.texas.gov/assets/public/ 

implementation/air/sip/haze/EWRT_AMDA_Pivot_

final.xlsx. This spreadsheet is also available in our 

docket as ‘‘Texas EWRT AMDA spreadsheet.xlsx’’. 

85See ‘‘EPA Q_d Spreadsheet.xlsx’’ available in 

the docket for this action. The information included 

in the EPA’s spreadsheet used information available 

in our docket as ‘‘Texas EWRT AMDA 

spreadsheet.xlsx’’. See also Letter from Arkansas 

Department of Energy and Environment to TCEQ 

requesting that TCEQ consider, among other 

sources, whether performing a four-factor analysis 

is appropriate for the W A Parish facility in 

accordance with 40 CFR 51.308(f)(2)(i) due to 

impacts on Caney Creek based on CenSARA’s AOI 

study (Feb. 4, 2020). The letter is available in 

Appendix A of Texas’s 2021 Regional Haze Plan at 

84 of 227. See also Letter from Oklahoma 

Department of Environmental Quality to TCEQ 

requesting that TCEQ consider further evaluating 

the W A Parish facility based on its identification 

that the source is reasonably anticipated to 

contribute to visibility impairment at the Wichita 

Mountains Wilderness Area (July 17, 2020). The 

letter is available in Appendix A of Texas’s 2021 

Regional Haze Plan at 125 of 227. 

86See AOI for Salt Creek located in ‘‘Texas EWRT 

AMDA spreadsheet.xlsx’’ available in the docket for 

this action. See ‘‘EPA Q_d Spreadsheet.xlsx’’ 

available in the docket for this action. See also 

Letter from New Mexico Environment Department 

to TCEQ requesting among other things that Texas 

specifically evaluate the Tolk facility for additional 

controls based on its impact to Class I areas in New 

Mexico, including Salt Creek (Feb. 2, 2021). The 

letter is available in Appendix A of Texas’s 2021 

Regional Haze Plan at 111 of 227. See also, 

information provided by the FLMs during 

consultation that Tolk and W A Parish merit further 

evaluation based on emissions and potential 

emission reductions available. The information 

provided by the FLMs is available in Appendix A 

of Texas’s 2021 Regional Haze Plan at 205 of 227. 

87See 2021 Texas Regional Haze Plan, appendix 

F, Figure 1–60. 

88EPA used information from Texas’s EWRT 

AMDA spreadsheet, also available in our docket as 

‘‘Texas EWRT AMDA spreadsheet.xlsx’’. We used 

the same information to calculate the SO2 Q/d 

values for Tolk at White Mountain (56) and at 

Wheeler Peak (42.7). 

a cell in the domain.’’ 80 The EPA 

compared the plotted AOIs Texas had 

submitted during the 2020 early 

engagement period with the plotted 

AOIs Texas submitted with its 2021 

Regional Haze Plan. These AOIs are the 

same, confirming that, despite what 

Texas stated in its 2021 Regional Haze 

Plan, Texas was actually following its 

articulated methodology in the 2020 

early engagement document. 

This early engagement information 

was not included in the proposed SIP 

Texas published during its state-level 

notice-and-comment process. Thus, 

Texas’s SIP failed to accurately or 

adequately describe the criteria actually 

used in its 2021 Regional Haze Plan 

submission to determine which sources, 

or groups of sources, it chose to evaluate 

for additional control measures as 

required by 40 CFR 51.308(f)(2)(i). 

Without an accurate and adequate 

description of Texas’s source selection 

methodology, it is not clear from its 

2021 Texas Regional Haze Plan how 

Texas evaluated and determined the 

emission reduction measures that are 

necessary to make reasonable progress 

for its second planning period long-term 

strategy. We discuss the AOI 

methodologies and these 

inconsistencies further in the Technical 

Support Document (TSD) included in 

the docket for this action. 

ii. Texas Failed To Adequately Justify 

Its AOI Threshold 

As noted in the previous section and 

more fully explained in the EPA’s TSD, 

Texas selected sources using AOIs it 

developed for each Class I area then 

followed with a Q/d analysis. The AOIs 

established a brightline geographic 

boundary within which Texas selected 

sources with a Q/d of greater than or 

equal to five. In other words, Texas did 

not consider a source, regardless of the 

size of its emissions, if it was not first 

within the geographic area defined by 

the chosen AOI threshold. 

To define the brightline geographic 

boundaries of the AOIs, Texas applied 

a threshold of 0.1 or 10% of the 

maximum EWRT value for that AOI.81

Texas did not provide any discussion or 

justification for its selection of this 

threshold, nor did Texas explain how 

this threshold resulted in evaluating a 

meaningful set of sources for possible 

controls measures to improve visibility 

impairment. Further, Texas did not 

evaluate whether the selected threshold 

provided for AOIs that included a 

sufficiently large area to capture the 

sources with the highest emissions, or 

Q/d values, that impact visibility at 

certain Class I areas. The need for a 

justification is crucial when a State is 

applying the threshold as a brightline 

when selecting sources to evaluate for 

additional control measures, such as 

what Texas did here. The AOIs 

generated from EWRTs represent the 

general location that air parcels are 

coming from when visibility extinction 

is high. However, unless an appropriate 

threshold value is applied, they do not 

necessarily capture the specific sources 

of emissions that are contributing to 

visibility impairment at the Class I 

area.82 Texas’s approach did not 

consider the size or location of point 

sources, despite articulating a specific 

focus on point sources,83 or the total 

emissions captured to support that their 

approach and chosen threshold resulted 

in a reasonable identification of sources 

for analysis in development of the long 

term strategy. This problem is evident in 

Texas’s 2021 Regional Haze Plan, where 

several AOIs contained no sources 

identified for further consideration and 

several large emission sources with Q/ 

d values far exceeding Texas’s Q/d 

threshold of five being excluded from 

further consideration because they were 

located outside of Texas’s generated 

AOIs. 

For example, W A Parish is located 

just outside of Texas’s ammonium 

sulfate AOIs for both Caney Creek and 

Wichita Mountains, and outside of 

Texas’s ammonium sulfate AOI for Big 

Bend.84 The SO2 Q/d values for W A 

Parish are 32.2 for Caney Creek, 28.2 for 

Wichita Mountains, and 25.1 for Big 

Bend.85 Tolk Generating Station is also 

located outside of Texas’s ammonium 

sulfate AOI for Salt Creek; however, it 

has a Q/d value of over 84.86

Ammonium sulfate is the largest 

contributor to observed light extinction 

at Salt Creek 87 but Texas did not 

identify any source of SO2 emissions for 

further analysis due to the application 

of their AOI brightline test and selected 

EWRT threshold, despite the large SO2

emissions from Tolk and the relative 

proximity of the facility to Salt Creek.88

Given the large emissions from these 

facilities, these sources likely are 

meaningfully contributing to visibility 

impairment, even if they happen to fall 

outside of the chosen Texas AOIs. Based 

on its analysis of other coal-fired EGUs 

with no controls or underperforming 

controls, had Texas selected these 

sources for further evaluation under the 

four factors, Texas may have found costeffective controls available, resulting in 

emission reductions that may have been 

necessary for inclusion in its long-term 

strategy to make reasonable progress 

toward meeting the national goal. 

Moreover, Texas did not explain how 

not evaluating these high-emitting 

sources nonetheless results in a longterm strategy that makes reasonable 

progress toward the national goal. 

We therefore find Texas’s unjustified 

use of its selected threshold and 

resulting AOIs as a brightline cutoff in 


khammond on DSKJM1Z7X2PROD with PROPOSALS2
83354 Federal Register / Vol. 89, No. 199 / Tuesday, October 15, 2024 / Proposed Rules 

89 2019 Guidance at 14–15. 

90 2021 Texas Regional Haze Plan at 8–2. 

91As explained in our 2019 Guidance, 

photochemical models are a more detailed and 

sophisticated technique for evaluating visibility 

impacts. Photochemical modeling considers the 

dispersion transformation and deposition processes. 

Source apportionment can ‘‘tag’’ and track 

emissions sources by any combination of region and 

sector, or by individual source. As evidenced in 

Appendix A of Texas’s 2021 Regional Haze Plan, 

Texas had the results of the PSAT modeling at least 

by March 31, 2020, when Texas presented the 

results to the FLMs during a consultation meeting. 

92CAA 169A(a)(1), (b)(2); 40 CFR 51.308(f)(2). 

93See 2021 Texas Regional Haze Plan Figure 8– 

21 at 8–46. 

94See 2021 Texas Regional Haze Plan Figure 8– 

21 at 8–46. 

95See 2021 Texas Regional Haze Plan, appendix 

F, Figure 1–52 at F–54 and Figure 1–53 at F–55. 

96See 2021 Texas Regional Haze Plan, appendix 

F, Figure 1–52 at F–54. 

97See 2021 Texas Regional Haze Plan, appendix 

F, Figure 1–52 at F–54. 

98See 2021 Texas Regional Haze Plan, appendix 

F at F–36. 

99See 2021 Texas Regional Haze Plan, appendix 

F at F–62. 100See 2021 Texas Regional Haze Plan, appendix 

F at F–63. 101Texas’s own modeling and the EPA’s 

modeling demonstrated that Salt Creek would be 

above the adjusted glidepath. 102See 2021 Texas Regional Haze Plan, appendix 

F, Figure 1–61 at F–63. 103 40 CFR 51.308(f)(2)(i) (‘‘The State must 

evaluate and determine the emission reduction 

measures that are necessary to make reasonable 

progress . . . 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’’). 

source selection to be unreasonable. 

Texas’s methodology resulted in several 

of the highest emitting SO2 stationary 

point sources in the State of Texas not 

being selected for further evaluation of 

controls to improve visibility 

impairment at the Class I areas they 

likely impact, and in the case of some 

Class I areas, no sources selected at all 

for further analysis using the four 

statutory factors for those areas. 

iii. PSAT Modeling Results Further 

Demonstrate Unreasonableness of 

Texas’s Source Selection Methodology 

The 2019 Guidance identifies 

photochemical modeling and the use of 

source apportionment modeling as 

possible methods to assess PM species 

impacts from sources or groups of 

sources for source selection.89 Texas 

conducted photochemical source 

apportionment modeling (known as the 

Particulate Matter Source 

Apportionment Technology, or PSAT, 

function of CAMx modeling) as part of 

its 2021 Regional Haze Plan to evaluate 

the impact of emissions from source 

categories on visibility in Class I areas.90

While Texas did not conduct PSAT 

modeling for the explicit purpose of 

source selection, Texas nevertheless 

included the results of the PSAT 

modeling in its SIP.91 The EPA finds 

Texas’s own PSAT modeling results 

illustrate the flaws in Texas’s source 

selection methodology. 

The TCEQ failed to address in its 

2021 Regional Haze Plan how its source 

selection approach and resulting failure 

to select sources for further analysis to 

address visibility impairment at Big 

Bend are consistent with the CAA’s 

statutory goal and Regional Haze Rule 

requirements.92 TCEQ’s source selection 

methodology did not identify any 

sources for further analysis of control 

measures that may be necessary to 

include in its long-term strategy to make 

reasonable progress at Big Bend. The 

TCEQ’s PSAT model results indicate 

that emissions from Texas 

anthropogenic sources account for over 

10% of the total light extinction at Big 

Bend, and 67% of the light extinction 

due to U.S. anthropogenic emissions. 93

The influence from Texas sources on 

light extinction at Big Bend is 

approximately double the influence 

from anthropogenic sources in the rest 

of the U.S. combined.94 While Texas 

states that visibility at Big Bend is 

heavily influenced by international 

emissions, the TCEQ has already 

accounted for this by adjusting the 

glidepath for its Class I areas to remove 

visibility impairment from international 

emissions, consistent with the EPA’s 

guidance, and thus should not be used 

as a rationale for not evaluating sources 

for additional control measures. CAA 

169A(a)(1), (b)(2) and the RHR require 

states to make reasonable progress 

towards addressing anthropogenic 

impairment from U.S. sources in the 

second planning period in furtherance 

of Congress’s national goal. 

The influence of Texas sources on 

sulfate and nitrate concentrations at Big 

Bend shows that emissions from Texas 

sources are projected to account for 

approximately 65.4% of the particulate 

sulfate concentration and 59.3% of the 

nitrate concentration due to U.S. 

anthropogenic emissions.95 The vast 

majority (93.9%) 96 of the Texas 

influence on particulate sulfate 

concentrations at Big Bend can be 

attributed to Texas anthropogenic 

emissions from electricity generating 

unit (EGU) point and non-EGU point 

sources.97 Therefore, these data 

demonstrate that Texas’s AOI analysis 

and threshold selection for Big Bend did 

not adequately identify the relevant 

sources that impact visibility 

impairment for further analysis 

necessary to develop a long-term 

strategy to make reasonable progress at 

Big Bend. 

Similarly, Texas’s PSAT modeling 

also underscores inadequacies with its 

source selection for Class I areas in New 

Mexico, for example, Salt Creek. As 

noted above, Texas’s AOI analysis for 

Salt Creek identified no sources of SO2

in Texas for consideration for further 

analysis. However, the results of Texas’s 

PSAT modeling show that Texas 

sources account for almost 12% of the 

light extinction at Salt Creek.98 The 

largest contributor to light extinction at 

Salt Creek is sulfate.99 Focusing on 

modeled U.S. anthropogenic impacts 

alone, Texas anthropogenic sources 

account for approximately 51.3% of the 

particulate sulfate concentrations at Salt 

Creek.100 Texas’s chosen approach for 

source selection failed to identify any 

SO2 point sources, despite accounting 

for over half of all the U.S. 

anthropogenic particulate sulfate 

concentrations at Salt Creek. 

Class I areas like Salt Creek that are 

not projected to be on or under the 

glidepath are subject to additional 

requirements in the RHR. Under 40 CFR 

51.308(f)(3)(ii)(B), Texas must provide a 

robust demonstration that there are no 

additional emission reduction measures 

for anthropogenic sources or groups of 

sources in the State that may reasonably 

be anticipated to contribute to visibility 

impairment in the Class I area that 

would be reasonable to include in its 

own long-term strategy.101 The 

influence from Texas’s point sources on 

particulate sulfate concentrations at Salt 

Creek is more than double the amount 

of New Mexico’s total (point source, 

non-point source, and mobile source) 

influence on particulate sulfate 

concentrations at Salt Creek.102

Meaning, SO2 emissions from Texas 

sources contribute more to visibility 

impairment at Salt Creek than SO2

emissions from New Mexico sources. 

Given the meaningful contribution to 

visibility impairment demonstrated by 

its PSAT modeling, Texas’s decision not 

to select any SO2 sources for further 

analysis and consideration of the four 

statutory factors (or to adequately justify 

the decision not to select these sources) 

fails to satisfy the requirement to 

provide for a robust demonstration for 

those Class I areas projected to be above 

the glidepath, as required by 40 CFR 

51.308(f)(3)(ii)(B). 

iv. EPA’s Conclusions and Proposed 

Action on Source Selection 

The EPA finds the source selection 

methodology used by Texas was not 

adequately described as required by the 

RHR.103 Nevertheless, the EPA was able 

to discern the state’s approach to 


khammond on DSKJM1Z7X2PROD with PROPOSALS2
Federal Register / Vol. 89, No. 199 / Tuesday, October 15, 2024 / Proposed Rules 83355 

104See 40 CFR 51.308(f)(2). 

105 2021 Texas Regional Haze Plan table 7–5 at 7– 

15. 

106 2021 Texas Regional Haze Plan at 7–11. 

107 40 CFR 51.308(f)(2)(i). 

108 2021 Texas Regional Haze Plan at 7–11. 

109 2019 Guidance at 22. 

110 40 CFR part 51, appendix Y, Section D, Step 

2. 

111 2019 Guidance at 22. 

112 2019 Guidance at 29–30. 

113 2021 Texas Regional Haze Plan, appendix B at 

B–1. 

114 2021 Texas Regional Haze Plan, appendix B at 

B–1 and B–5 to B–6. 

115 2021 Texas Regional Haze Plan, appendix B at 

B–1. 

116 2021 Texas Regional Haze Plan, appendix B at 

B–3. 

developing its AOIs which relied upon 

drawing a boundary based on a 

threshold of ten percent of the 

maximum EWRT values. Texas, 

however, did not provide any rationale 

or justification for this ten percent 

threshold. The boundaries of the AOIs 

were used as a brightline cutoff, with 

sources outside the AOIs not given any 

further consideration. As demonstrated 

in previous sections, Texas’s 

methodology was unreasonable because 

it resulted in the selection of no sources 

for further evaluation at Big Bend and 

no SO2 sources for further analysis at 

Salt Creek. Texas’s own PSAT modeling 

results confirm that its methodology 

was unreasonable because the results 

show significant contribution from 

Texas anthropogenic sources to 

visibility impairment at Big Bend and 

Salt Creek. Texas made no attempt to 

explain the disconnect between its 

PSAT results and its source selection 

approach. 

The selection of a reasonable set of 

sources is a necessary first step in 

identifying the required emission limits, 

schedules of compliance, and other 

measures as may be necessary for 

inclusion in its long-term strategy to 

make reasonable progress toward 

meeting Congress’s goal of preventing 

any future, and remedying any existing, 

impairment at Class I areas after 

consideration of the four statutory 

factors.104 It is evident that developing 

a long term strategy to make reasonable 

progress cannot be met, if no sources of 

pollutants shown to be meaningful 

contributors to impairment are selected 

for further evaluation. It is further 

evident that, at least for Big Bend for 

both NOX and SO2 and for Salt Creek for 

SO2, Texas’s method of establishing an 

AOI is not adequate to identify sources 

of visibility impairment in Texas. 

Therefore, the EPA is proposing to 

disapprove the portion of Texas’s 2021 

Regional Haze Plan addressing the 

regulatory requirements of the long-term 

strategy under 40 CFR 51.308(f)(2). 

2. Four Factor Analysis 

This section discusses the technical 

bases and information Texas relied on 

in the evaluation of emission reduction 

measures necessary to make reasonable 

progress in each Class I area affected by 

emissions from Texas when developing 

its long-term strategy for the second 

planning period. As discussed in the 

preceding section, Texas selected 18 

sources for evaluation of emissions 

reductions necessary to make reasonable 

progress.105 If a source triggered 

analysis for both NOX and SO2, control 

strategies for both pollutants were 

analyzed separately and 

concurrently.106 Of the 18 sources 

selected for evaluation, eight are EGU 

sources and 10 are non-EGU sources. 

Based on the statutory and regulatory 

requirements, Texas evaluated emission 

reduction measures that are necessary to 

make reasonable progress by 

considering the four statutory factors 

listed in CAA § 169A(g)(1) and 40 CFR 

51.308(f)(2)(i) for these selected sources. 

The four statutory factors are (1) the cost 

of compliance; (2) the time necessary for 

compliance; (3) the energy and non-air 

quality environmental impacts of 

compliance; and (4) the remaining 

useful life of any potentially affected 

sources. This is commonly referred to as 

‘‘the four-factor analysis.’’ The four 

statutory factors must be considered 

when evaluating and determining the 

emissions reductions measures that are 

necessary to make reasonable 

progress.107 Although visibility impact 

is not one of the factors required for 

consideration under the CAA and the 

RHR, Texas opted to evaluate and 

consider the visibility benefits from 

selected control measures evaluated in 

the four-factor analysis by conducting 

photochemical sensitivity modeling.108

In the subsections that follow, we 

discuss Texas’s analysis of the four 

statutory factors. 

a. Identification of Potential Controls 

In accordance with EPA’s 2019 

Guidance, ‘‘the first step in 

characterizing control measures for a 

source is the identification of 

technically feasible control measures for 

those pollutants that contribute to 

visibility impairment.’’ 109 The EPA’s 

2019 Guidance does not define the term 

‘‘technically feasible;’’ however, EPA’s 

Regional Haze Regulations and 

Guidelines for Best Available Retrofit 

Technology (BART) Determinations (the 

BART Guidelines) states: 

Control technologies are technically 

feasible if either (1) they have been installed 

and operated successfully for the type of 

source under review under similar 

conditions, or (2) the technology could be 

applied to the source under review. Two key 

concepts are important in determining 

whether a technology could be applied: 

‘‘availability’’ and ‘‘applicability.’’ . . . a 

technology is considered ‘‘available’’ if the 

source owner may obtain it through 

commercial channels, or it is otherwise 

available within the common sense meaning 

of the term. An available technology is 

‘‘applicable’’ if it can reasonably be installed 

and operated on the source type under 

consideration. A technology that is available 

and applicable is technically feasible.110

A reasonable four-factor analysis will 

consider the full range of potentially 

reasonable options for reducing 

emissions.111 In order to provide 

guidance on what control measures 

should be included in their four-factor 

analysis, the RHR Guidance lists 

examples of different types of control 

measures that states may consider.112

For EGUs without existing controls, 

Texas considered and evaluated dry 

sorbent injection (DSI), spray dryer 

absorber (SDA), and wet limestone 

scrubbing systems (wet FGD) as 

potential SO2 control options, and 

selective catalytic reduction (SCR) and 

selective non-catalytic reduction (SNCR) 

as potential NOx controls.113 For EGUs 

with existing SO2 controls, Texas 

considered and evaluated upgrading the 

control efficiency of the controls to 

95%.114 For non-EGUs, Texas 

considered various NOX and SO2

control options depending on the type 

of source and whether it had existing 

controls.115

For selected sources where Texas 

could not identify any feasible control 

options for a particular source-type, that 

particular source and pollutant was not 

further evaluated in the four-factor 

analysis. Texas stated that it only 

considered control technologies that 

have been demonstrated as technically 

feasible for units at each source type 

and evaluated those control 

technologies using available unitspecific data. Texas deemed a given 

control technology to be ‘‘demonstrated 

to be technically feasible’’ if it was 

identified in the EPA’s Reasonably 

Available Control Technology/Best 

Available Control Technology/Lowest 

Achievable Emission Rate (RACT/ 

BACT/LAER) Clearinghouse or operated 

in industrial applications for units 

within an industry type not in a 

performance ‘‘trial’’ phase.116 Texas 

further explained that a control measure 

or technique that has been established 

as technically demonstrated or feasible 


khammond on DSKJM1Z7X2PROD with PROPOSALS2
83356 Federal Register / Vol. 89, No. 199 / Tuesday, October 15, 2024 / Proposed Rules 

117See RACT/BACT/LAER Clearinghouse (RBLC) 

Basic Information available at https://www.epa.gov/ 

catc/ractbactlaer-clearinghouse-rblc-basicinformation. 

118See, e.g., Port Arthur Steam Energy/Oxbow 

Corp., available at https://chptap.ornl.gov/profile/ 

186/Port_Arthur_Steam-Project_Profile.pdf. 

119Bay Area Air Quality Management District 

Regulation 9, Rule 14 Report at 4, 9 (Oct. 2015). 

120Bay Area Air Quality Management District 

Regulation 9, Rule 14 Report at 11 (Oct. 2015). 

121 2021 Texas Regional Haze Plan, Response to 

Comments, at 481–482 of 653. 

122See EPA’s TSD for this action, available in the 

docket, for additional information regarding the 

installation and operation of controls on petroleum 

coke calcining plants. 

123 40 CFR 51.308(f)(2)(iii). 

124Oxbow Comments on 2021 Texas Regional 

Haze Plan, at 306 of 653. According to a 2022 

technical support document (TSD) prepared by 

EPA, there are only approximately 15 petroleum 

coke calcining facilities operating in the United 

States. The EPA 2022 TSD is available in the docket 

for this action. 

125Oxbow Comments on 2021 Texas Regional 

Haze Plan, Report from Sargent & Lundy at 312 of 

653. 

126Oxbow Comments on 2021 Texas Regional 

Haze Plan, Report from Sargent & Lundy at 338 of 

653. 

127Oxbow Comments on 2021 Texas Regional 

Haze Plan, Report from Sargent & Lundy at 336 of 

653. 

128Oxbow Comments on 2021 Texas Regional 

Haze Plan, Report from Sargent & Lundy at 334 of 

653. 

129Oxbow Comments on 2021 Texas Regional 

Haze Plan, Report from Sargent & Lundy at 336 of 

653. 

130We discuss additional examples of existing 

controls at coke calcining facilities in the TSD for 

this action, included in the docket. 

131See 2021 Texas Regional Haze SIP, Comments 

by Sierra Club, et al., on Texas’s Regional Haze SIP 

at 253 of 653. 

in one industry type was not considered 

to extend automatically to other 

industry types. Based on Texas’s 

approach, Texas determined that there 

were no technically feasible controls for 

three of the 18 sources selected for 

further evaluation using the four factors: 

the Orion Carbon Black facility in 

Orange County, the Oxbow Calcining 

facility in Jefferson County, and the 

Streetman facility in Navarro County. 

These three determinations are 

discussed in more detail in the 

following paragraphs. 

Initially we note that Texas’s search 

for available controls relied primarily on 

the RACT/BACT/LAER Clearinghouse. 

BACT and LAER are terms associated 

with EPA’s ‘‘New Source Review’’ 

(NSR) permitting program and is 

triggered when a company is planning 

to build a new plant or modify an 

existing plant such that air pollution 

emissions will increase by a large 

amount. EPA established the RACT/ 

BACT/LAER Clearinghouse to provide a 

central data base of air pollution 

technology information (including past 

RACT, BACT, and LAER decisions 

contained in NSR permits) to promote 

the sharing of information among 

permitting agencies and to aid in future 

case-by-case determinations.117 We note 

that many of the petroleum coke 

calcining plants and carbon black plants 

were constructed prior to the start of 

EPA’s NSR permitting program and 

have generally not been modified in 

ways that would trigger the permitting 

programs.118 As a result, Texas’s 

reliance on that RACT/BACT/LAER 

Clearinghouse is not a sufficient search 

for these types of facilities. 

In fact, several groups commented 

during Texas’s state-level comment 

period that there were technically 

feasible controls available for petroleum 

coke calcining facilities similar to the 

Oxbow facility. For example, 

commenters referenced a report which 

includes a discussion of a petroleum 

coke calcining plant that currently 

operates a DSI system to control 

emissions.119 Additionally, the report 

identifies a Tesoro facility that operates 

a semi-dry scrubber combined with a 

wet electrostatic precipitator that 

reduces SO2 emissions in excess of 

95%.120 In response to these comments, 

Texas stated that: 

The control technology the commenter 

provided may be technically feasible for 

petroleum coke calcining manufacturing sites 

but would not necessarily be considered 

technically demonstrated directly on the 

kilns such that this technology could be 

implemented at Oxbow’s Port Arthur facility 

as suggested by the commenter. The possible 

control options suggested by the commenter 

would require modification to a site’s 

operational process such that a potential SO2

post-combustion control strategy could 

technically be implemented to control SO2

emissions from petroleum coke calcining 

kilns. The TCEQ notes these potential 

strategies would be implemented 

downstream of the kiln, or kilns, and not 

directly on the kiln. The operational process 

modification would require additional 

process units to the site to make the potential 

post-combustion SO2 control measure 

technically feasible, thereby increasing 

capital expenditures not directly associated 

with the new, additional control measure but 

necessary for the control measure to 

effectively function and control SO2

emissions from the petroleum coke calcining 

kiln. The TCEQ contends these higher-level 

control analysis approaches require much 

broader and resource intensive engineering 

and economic analyses, and they may not 

result in the potential control strategy being 

deemed cost-effective or reasonable and 

necessary for making reasonable progress for 

long-term strategies for a planning period.121

While Texas’s response indicates that 

such control technologies may not be 

cost effective based on the modifications 

that may need to occur at the site, such 

a determination would necessarily come 

out of a four-factor analysis; it does not 

explain why Texas’s SIP continued to 

find that such control measures were 

not technically feasible.122 In fact, it 

acknowledges that such control 

technologies may be technically 

feasible. To the extent Texas is relying 

on the fact that the costs of this control 

technology would be prohibitive, Texas 

needed to provide a cost analysis to 

document and support such an 

assumption.123

Furthermore, information provided by 

Oxbow during Texas’s comment period 

acknowledge that while there is limited 

publicly available information there are 

‘‘a few commercially operating postcombustion SO2 controls systems 

installed on petroleum coke kilns.’’ 124

Oxbow also provided a four-factor 

analysis conducted by Sargent & 

Lundy.125 Specifically, Sargent & Lundy 

concluded that, based on engineering 

judgment and information from control 

system vendors, several control 

technologies were technically feasible 

and commercially available including: a 

DSI system with a fabric filter; 126 a 

spray dryer flue gas scrubber system; 127

a wet limestone scrubbing system; 128

and a circulating dry scrubber 

system.129 Despite information provided 

to Texas to the contrary, the State 

continued to find that control 

technologies were not technically 

feasible. Therefore, Texas’s 

determination that such control 

technologies were not technically 

feasible for petroleum coke calcining 

facilities was not reasonable. As a result, 

because Texas selected this source for 

further evaluation of control measures, 

it was unreasonable for Texas to not 

take into consideration the four 

statutory factors to determine whether 

there were cost-effective measures that 

were thus necessary for reasonable 

progress in fulfillment of their long-term 

strategy requirements for the second 

planning period.130

Texas received similar comments 

regarding Texas’s determination that 

there were no feasible controls for the 

Orion carbon black plant. Notably, the 

commenter states that the EPA had 

entered into consent decrees with 

several carbon black manufacturing 

companies that required control of SO2

emissions to 95%.131 In response to 

these comments, Texas stated that while 

these consent decrees required certain 

control efficiencies, installing controls 

on carbon black facilities had yet to be 

demonstrated in practice. However, the 

EPA entered into a consent decree with 


khammond on DSKJM1Z7X2PROD with PROPOSALS2
Federal Register / Vol. 89, No. 199 / Tuesday, October 15, 2024 / Proposed Rules 83357 

132See, United States of America, et al. v. Cabot 

Corporation, Civil Action Number 6:13–cv–03095 

(W.D. LA), Second Amendment to Consent Decree 

(filed Dec. 22, 2017) and available in the docket for 

this action. 

133See Cabot press release dated June 26, 2020, 

regarding the successful installation of control 

technologies, available at https://investor.cabotcorp.com/node/21156. 

134See 2021 Texas Regional Haze Plan, 

Comments by Sierra Club, et al. on Texas’s Regional 

Haze SIP at 252 of 653. 

135AP–42 emission factors are published by EPA 

and serve as the primarily compilation of emission 

factor information. The various chapters contain 

emissions factors and process information for more 

than 200 air pollution source categories. A source 

category is a specific industry sector or group of 

similar emitting sources. The emissions factors have 

been developed and compiled from source test data, 

material balance studies, and engineering estimates. 

See AP–42: Compilation of Air Emissions Factors 

from Stationary Sources available at https://

www.epa.gov/air-emissions-factors-andquantification/ap-42-compilation-air-emissionsfactors-stationary-sources for more information. 

136 2021 Texas Regional Haze Plan, Response to 

Comments at 482–483 of 653. 

137AP–42, section 11.20 available at https://

www.epa.gov/air-emissions-factors-andquantification/ap-42-fifth-edition-volume-i-chapter11-mineral-products-0 and in the docket for this 

action. 

138See AP–42, section 11.20 See also AP–42 

section 11.20 at pgs. 5, 10–12. 

139See AP–42, section 11.20, table 4–13, 

Emission factors for rotary kilns without a scrubber 

are 5.6 lbs SO2/ton feed, with a scrubber 3.4 lbs 

SO2/ton feed. 

140See 2021 Texas Regional Haze Plan, 

Comments by Sierra Club, et al, on Texas’s Regional 

Haze SIP at 252 of 653. See also 2021 Texas 

Regional Haze Plan, appendix A at 206 of 227. 

141 2021 Texas Regional Haze Plan, appendix B. 

142 2021 Texas Regional Haze Plan, appendix B at 

B–3. 

143 2021 Texas Regional Haze Plan at 7–11 to 7– 

12. 

144 2021 Texas Regional Haze Plan, appendix B at 

B–12. 

145 2021 Texas Regional Haze Plan, appendix B at 

B–12. 

146 2021 Texas Regional Haze Plan, appendix B at 

B–7 to B–8, B–12. 

147 2021 Texas Regional Haze Plan, appendix B at 

B–14. 

148 2021 Texas Regional Haze Plan, appendix B at 

B–14. 

the carbon black manufacturing 

company Cabot, which required the 

installation of wet gas scrubbers to 

control SO2 emissions from their carbon 

black units. While the compliance dates 

were delayed,132 Cabot completed 

construction of the wet gas scrubber at 

its Canal Plant in 2020.133 Thus, the 

available information identifies 

technically feasible and available 

control technologies for carbon black 

facilities. Therefore, Texas’s 

determination that no control 

technologies were technically feasible 

was unreasonable. Texas should have 

conducted a four-factor analysis for the 

Orion carbon black plant considering 

these available controls to determine 

whether cost-effective control measures 

were necessary for reasonable progress 

in fulfillment of its long-term strategy 

requirements. 

Texas also received comments during 

Texas’s state-level public comment 

period that there were technically 

feasible controls identified for 

lightweight aggregate plants like 

Streetman’s plant.134 Specifically, 

commenters referenced EPA’s AP–42 

emission factor documentation 135 for 

lightweight aggregate manufacturing. 

Among other information, the document 

identifies that emissions from kilns at 

these lightweight aggregate facilities are 

controlled with wet scrubbers as well as 

fabric filters and electrostatic 

precipitators (ESPs). In response to this 

information, Texas stated that review of 

the data and information in the EPA’s 

AP–42 emission factor dataset led the 

TCEQ to conclude that ‘‘while wet 

scrubbers designed for PM control may 

result in some emissions reductions of 

SO2, the TCEQ does not view this as a 

control strategy for the direct control of 

SO2 that could result in meaningful SO2

emissions reductions.’’ 136

While the EPA’s AP–42 emission 

factor documentation discusses the use 

of scrubbers to control PM emissions, it 

also provides information and emission 

factors related to the control of SO2

emissions from the installation of wet 

scrubbers.137 Several of the studies 

referenced in the documentation were 

done to measure SO2 emissions.138 This 

information together shows reductions 

in emissions of SO2 from the installation 

of wet scrubbers at lightweight aggregate 

plants.139 Regardless of whether the 

main pollutant of concern from these 

types of facilities is PM or SO2, Texas 

does not adequately or reasonably 

explain how a proven control 

technology, installed within the same 

industry type and for which reduces the 

pollutant of concern (SO2), becomes 

technically infeasible based on the fact 

that it also reduces PM. Texas’s 

determination that there were no 

technically available controls for 

lightweight aggregate plants such as the 

Streetman facility was unreasonable and 

unsupported by information provided to 

Texas during its public comment 

period.140 Therefore, it was 

unreasonable for Texas not to have 

evaluated potential control measures for 

the Streetman facility using the four 

statutory factors to determine whether 

control measures were necessary for 

reasonable progress in fulfillment of 

their long-term strategy requirements. 

b. Cost of Compliance 

Texas evaluated the cost of 

compliance for each control option 

determined to be technically feasible for 

each selected EGU and non-EGU to 

arrive at an annualized cost and cost per 

ton of emissions reduced ($/ton), also 

referred to as a cost-effectiveness 

calculation, for each control option.141

Texas stated that as part of the cost 

analysis, individual units at a source 

selected for evaluation with NOX or SO2

emissions of less than five percent of the 

facility’s total emissions of the same 

pollutant were eliminated from further 

analysis.142 Texas explained that 

excluding such units with smaller 

emissions is reasonable with respect to 

application of the cost of compliance 

criterion because controlling these 

smaller units would not be justified at 

this time considering both the cost to 

control and the anticipated 

improvement in visibility. Using this 

approach, Texas focused on the units 

with relatively greater NOX and SO2

emissions at a given source. 

In the cost analysis for EGUs without 

existing controls, Texas stated it 

estimated the capital cost and annual 

operating and maintenance costs of 

technically feasible air pollution control 

options using the most recent data 

available from Sargent & Lundy.143 In 

the cost analysis for upgrading 

scrubbers at EGUs, Texas provided an 

example cost, but did not explain how 

that example was used.144 In the cost 

analysis for non-EGUs, Texas stated it 

estimated the capital cost and annual 

operating and maintenance costs of 

technically feasible air pollution control 

options using cost data and information 

from the EPA and available industry 

literature.145 For one non-EGU source, 

the Works No. 4 Glass Plant, Texas 

relied on vendor cost information for 

capital cost and annual operating and 

maintenance costs of control 

equipment.146 For all sources, Texas 

estimated annualized capital costs by 

multiplying the capital costs by the 

capital recovery factor.147 The capital 

recovery factor accounts for source 

financing of air pollution control 

equipment and is based on the assumed 

equipment life and interest rate. Texas 

stated that ‘‘capital recovery factors 

were estimated using the techniques 

listed in the EPA’s Control Cost 

Manual’’ where it found appropriate.148

Texas estimated the capital recovery 

factor assuming an interest rate of 10 

percent and an equipment life of five, 

15, and 30 years. Ultimately, Texas 

chose to base its cost analysis on a 


khammond on DSKJM1Z7X2PROD with PROPOSALS2
83358 Federal Register / Vol. 89, No. 199 / Tuesday, October 15, 2024 / Proposed Rules 

149 2021 Texas Regional Haze Plan, appendix B at 

B–14. 

150 2021 Texas Regional Haze Plan, appendix B at 

B–14. 

151 2021 Texas Regional Haze Plan, appendix B at 

B–14. 

152 2021 Texas Regional Haze Plan, appendix B at 

B–14. 

153 2021 Texas Regional Haze Plan, appendix B at 

B–15. 

154The information contained in tables 8 through 

table 17 are presented in the 2021 Texas Regional 

Haze Plan, appendix B at B–16–B–42. 

capital life of 15 years for all selected 

sources.149

Texas stated that annual operating 

and maintenance costs associated with 

each control option evaluated ‘‘were 

estimated from the same data and 

information used for estimating capital 

costs for each source.’’ 150 Texas added 

the annualized capital cost and the 

annual operating and maintenance cost 

to arrive at the total annualized cost for 

each control option for each source.151

After estimating the potential emission 

reductions of each control option using 

baseline emissions from the EPA’s 2018 

Clean Air Markets Program Data 

(AMPD) emission data for EGUs and 

2016 TCEQ point source emission 

inventory data for non-EGUs, the total 

annualized cost was divided by the tons 

of pollutant emissions reduced to 

estimate the cost per ton of emissions 

reduced ($/ton), or cost-effectiveness.152

Texas then applied a cost-effectiveness 

($/ton) threshold of $5,000/ton for NOX

and SO2 emissions reduced to eliminate 

controls from further consideration by 

explaining that this allowed for the 

identification of sources to which 

potential control measures could be 

applied cost-effectively.153 The results 

of Texas’s cost analysis are presented in 

the following tables.154

TABLE 8—TEXAS’s COST ESTIMATES OF SO2 CONTROLS FOR EGUS WITHOUT EXISTING CONTROLS

Source 

SO2

baseline 

emissions 

(tons/yr) 

Control 

Control 

efficiency 

(%) 

SO2

reduction 

(tons/yr) 

5-Year 

life costeffectiveness 

($/ton) 

15-Year 

life costeffectiveness 

($/ton) 

30-Year 

life costeffectiveness 

($/ton) 

Coleto Creek Unit 1 ........................................... 13,213 DSI ..................

SDA .................

Wet FGD .........

90 

95 

98 

11,892 

12,552 

12,949 

$3,261 

6,720 

7,406 

$3,022 

3,884 

4,215 

$2,976 

3,340 

3,603 

Welsh Unit 1 ...................................................... 7,528 DSI ..................

SDA .................

Wet FGD .........

90 

95 

98 

6,775 

7,152 

7,377 

4,406 

11,380 

12,032 

4,029 

6,481 

6,812 

3,957 

5,540 

5,811 

Welsh Unit 3 ...................................................... 6,694 DSI ..................

SDA .................

Wet FGD .........

90 

95 

98 

6,025 

6,359 

6,560 

4,814 

12,622 

13,357 

4,394 

7,179 

7,558 

4,314 

6,135 

6,445 

TABLE 9—TEXAS’s COST ESTIMATES OF SO2 WET SCRUBBER UPGRADES FOR EGUS

Source Unit size 

(MW) 

SO2

baseline 

emissions 

(tons/yr) 

Capital 

cost 

($) 

Annual 

operating and 

maintenance 

costs 

($) 

SO2 reduction 

due to scrubber 

upgrade at 95% 

control efficiency 

(tons/yr) 

Cost-effectiveness 

($/ton) 

5-Year 

life 

15-Year 

life 

30-Year 

life 

AEP Pirkey Unit 1 ............................................... 721 5,085 99,921,030 2,740,188 3,874 $7,511 $4,098 $3,443 

Limestone Unit 1 ................................................. 893 4,156 123,757,947 3,393,881 3,212 11,222 6,123 5,145 

Limestone Unit 2 ................................................. 957 4,164 132,627,498 3,637,115 3,259 11,853 6,467 5,434 

Martin Lake Unit 1 ............................................... 793 19,282 109,899,275 3,013,827 16,172 1,979 1,080 907 

Martin Lake Unit 2 ............................................... 793 17,167 109,899,275 3,013,827 14,101 2,270 1,238 1,040 

Martin Lake Unit 3 ............................................... 793 19,749 109,899,275 3,013,827 16,458 1,945 1,061 891 

San Miguel Unit 1 ............................................... 410 12,006 56,820,558 1,558,221 2,001 8,270 4,512 3,791 

Oklaunion Unit 1 ................................................. 720 2,191 99,782,444 2,736,387 1,826 15,913 8,682 7,295 

TABLE 10–TEXAS’s COST ESTIMATES OF NOX CONTROLS OKLAUNION UNIT 1 

Source 

NOX

baseline 

emissions 

(tons/yr) 

Control 

Control 

efficiency 

(%) 

NOX

reduction 

(tons/yr) 

5-Year 

life costeffectiveness 

($/ton) 

15-Year 

life costeffectiveness 

($/ton) 

30-Year 

life costeffectiveness 

($/ton) 

Oklaunion Unit 1 ................................................ 6,804 SNCR ..............

SCR .................

50 

98 

3,402 

6,668 

$4,705 

11,222 

$4,152 

6,455 

$4,046 

5,541 

TABLE 11—TEXAS’s COST ESTIMATE OF SO2 WET SCRUBBER UPGRADES FOR MIDLOTHIAN PLANT

Unit 

SO2

baseline 

emissions 

(tons/yr) 

Baseline 

SO2 control 

efficiency 

of wet 

scrubber 

(%) 

Capital 

cost 

($) 

Annual 

operating and 

maintenance 

costs 

($) 

SO2 reduction 

due to scrubber 

upgrade at 95% 

control efficiency 

(tons/yr) 

Cost-effectiveness 

($/ton) 

5-Year 

life 

15-Year 

life 

30-Year 

life 

Cement Kiln No 1 ................................................ 522 90 8,196,683 224,782 261 $9,138 $4,986 $4,189 

Cement Kiln No 2 ................................................ 856 90 8,300,438 227,627 428 5,647 3,081 2,589 


khammond on DSKJM1Z7X2PROD with PROPOSALS2

I I I I I 
Federal Register / Vol. 89, No. 199 / Tuesday, October 15, 2024 / Proposed Rules 83359 

TABLE 12—TEXAS’s COST ESTIMATE OF TRI-MER CAT CONTROLS FOR VITRO FLAT GLASS WORKS NO 4 PLANT

Unit Pollutant 

evaluated 

Baseline 

emissions 

(tons/yr) 

Control 

efficiency 

evaluated 

(%) 

Emissions 

reduction 

(tons/yr) 

5-Year 

life costeffectiveness 

($/ton) 

15-Year 

life costeffectiveness 

($/ton) 

30-Year 

life costeffectiveness 

($/ton) 

Glass Melting Furnace Line No.1 .............. SO2 .......................

NOX ......................

136 

674 

80 

80 

109 

539 

$15,100 

15,100 

$10,300 

10,300 

$9,400 

9,400 

Glass Melting Furnace Line No. 2 ............. SO2 .......................

NOX ......................

301 

2,533 

80 

80 

241 

2,026 

4,600 

4,600 

3,200 

3,200 

2,900 

2,900 

TABLE 13—TEXAS’S COST ESTIMATES OF NOX CONTROLS FOR GRAPHIC PACKAGING TEXARKANA MILL

Unit 

NOX

baseline 

emissions 

(tons/yr) 

Control 

Control 

efficiency 

(%) 

NOX

reduction 

(tons/yr) 

5-Year 

life costeffectiveness 

($/ton) 

15-Year 

life costeffectiveness 

($/ton) 

30-Year 

life costeffectiveness 

($/ton) 

Power Boiler No 1 ............................................. 109 LNB .................

SCR .................

40 

80 

44 

87 

$21,788 

36,200 

$10,859 

26,350 

$8,762 

24,469 

Power Boiler No 2 ............................................. 692 LNB .................

SCR .................

40 

80 

277 

554 

3,525 

7,100 

1,757 

5,254 

1,417 

4,956 

Recovery Boiler/Furnace No 1 .......................... 275 LNB .................

SCR .................

40 

80 

110 

220 

7,438 

11,800 

3,707 

9,248 

2,991 

8,755 

Recovery Boiler/Furnace No 2 .......................... 674 LNB .................

SCR .................

40 

80 

270 

539 

3,619 

7,000 

1,804 

5,395 

1,455 

5,089 

TABLE 14—TEXAS’s COST ESTIMATES OF NOX CONTROLS FOR EL PASO NATURAL GAS COMPANY KEYSTONE

COMPRESSOR STATION

Unit 

NOX

baseline 

emissions 

(tons/yr) 

Control 

Control 

efficiency 

(%) 

NOX

reduction 

(tons/yr) 

5-Year 

life costeffectiveness 

($/ton) 

15-Year 

life costeffectiveness 

($/ton) 

30-Year 

life costeffectiveness 

($/ton) 

Reciprocating Internal Combustion Engine, 

A01.

131 LEC .................

SCR .................

40 

80 

53 

105 

$1,091 

7,956 

$544 

6,754 

$439 

6,523 

Reciprocating Internal Combustion Engine, 

A02.

7 LEC .................

SCR .................

40 

80 

3 

6 

19,209 

129,200 

9,573 

108,036 

7,724 

103,974 

Reciprocating Internal Combustion Engine, 

A03.

133 LEC .................

SCR .................

40 

80 

53 

106 

1,078 

7,900 

537 

6,677 

433 

6,449 

Reciprocating Internal Combustion Engine, 

A04.

14 LEC .................

SCR .................

40 

80 

6 

11 

9,989 

67,500 

4,978 

56,494 

4,017 

54,381 

Reciprocating Internal Combustion Engine, 

A05.

24 LEC .................

SCR .................

40 

80 

10 

19 

5,964 

40,600 

2,972 

33,990 

2,398 

32,729 

Reciprocating Internal Combustion Engine, 

A06.

17 LEC .................

SCR .................

40 

80 

7 

13 

8,664 

58,600 

4,318 

49,085 

3,484 

47,253 

Reciprocating Internal Combustion Engine, 

A07.

14 LEC .................

SCR .................

40 

80 

6 

11 

10,278 

69,400 

5,122 

58,102 

4,133 

55,928 

Reciprocating Internal Combustion Engine, 

A08.

18 LEC .................

SCR .................

40 

80 

12 

24 

4,851 

33,100 

2,418 

27,769 

1,915 

26,743 

Reciprocating Internal Combustion Engine, 

A09.

16 LEC .................

SCR .................

40 

80 

6 

13 

9,154 

61,900 

4,562 

51,821 

3,681 

49,885 

Reciprocating Internal Combustion Engine, 

A10.

60 LEC .................

SCR .................

40 

80 

24 

48 

2,377 

16,600 

1,185 

13,940 

956 

13,437 

Reciprocating Internal Combustion Engine, 

A11.

34 LEC .................

SCR .................

40 

80 

14 

27 

4,178 

28,600 

2,083 

24,011 

1,680 

23,127 

Reciprocating Internal Combustion Engine, 

A12.

8 LEC .................

SCR .................

40 

80 

3 

6 

18,554 

124,800 

9,247 

104,367 

7,461 

100,443 

Reciprocating Internal Combustion Engine, 

B01.

29 LEC .................

SCR .................

40 

80 

12 

23 

6,727 

39,100 

3,353 

32,227 

2,705 

30,914 

Reciprocating Internal Combustion Engine, 

B02.

83 LEC .................

SCR .................

40 

80 

33 

66 

2,365 

14,200 

1,179 

11,755 

951 

11,293 

Reciprocating Internal Combustion Engine, 

B03.

66 LEC .................

SCR .................

40 

80 

26 

53 

2,958 

17,600 

1,474 

14,543 

1,189 

13,965 

TABLE 15—TEXAS’s COST ESTIMATES OF NOX CONTROLS FOR EL PASO NATURAL GAS COMPANY CORNUDAS PLANT

Unit 

NOX

baseline 

emissions 

(tons/yr) 

Control 

Control 

efficiency 

(%) 

NOX

reduction 

(tons/yr) 

5-Year 

life costeffectiveness 

($/ton) 

15-Year 

life costeffectiveness 

($/ton) 

30-Year 

life costeffectiveness 

($/ton) 

Gas Turbine, A1 ................................................ 69 LNB .................

SCR .................

40 

80 

28 

55 

$1,913 

27,700 

$954 

21,972 

$769 

20,879 

Gas Turbine, A2 ................................................ 50 LNB .................

SCR .................

40 

80 

20 

40 

5,823 

37,742 

2,902 

29,958 

2,341 

28,464 

Gas Turbine, A3 ................................................ 63 LNB .................

SCR .................

40 

80 

25 

51 

4,623 

30,292 

2,304 

24,112 

1,859 

22,926 

Gas Turbine, B1 ................................................ 104 LNB .................

SCR .................

40 

80 

42 

83 

3,748 

22,878 

1,868 

17,982 

1,507 

17,042 

Gas Turbine, C1 ................................................ 18 SCR ................. 80 14 129,955 101,694 96,270 


khammond on DSKJM1Z7X2PROD with PROPOSALS2
83360 Federal Register / Vol. 89, No. 199 / Tuesday, October 15, 2024 / Proposed Rules 

155 40 CFR 51.308(f)(2)(iii). 

156 2021 Texas Regional Haze Plan, Response to 

Comments at 478–479 of 653. 

157 2021 Texas Regional Haze Plan, Response to 

Comments at 479 of 653. 

158See 40 CFR 51.308(f)(2)(i) (‘‘The State must 

evaluate and determine the emission reduction 

measures that are necessary to make reasonable 

progress by considering the costs of compliance 

. . .’’); CAA 169A(g)(1) (‘‘in determining reasonable 

progress, there shall be taken into consideration the 

costs of compliance . . .’’). 

159As discussed in the following section, the EPA 

requested the additional supporting information 

from Texas. In response, Texas provided additional 

files and spreadsheets to EPA upon request. 

However, the public did not have access to these 

files during the state-level comment period and 

therefore did not have an opportunity to review or 

comment on the complete technical basis of Texas’s 

cost analyses. 

160 2019 Guidance at 31. As we have previously 

noted in relation to BART determinations, 

‘‘[w]ithout an ‘apples-to-apples’ comparison of 

costs, it is impossible to draw rational conclusions 

about the reasonableness of the costs of compliance 

for particular control options. Use of the [Control 

Cost Manual] methodology is intended to allow a 

fair comparison of pollution control costs between 

similar applications for regulatory purposes.’’ 77 FR 

72512, 72518. 

161 2019 Guidance at 31. 

162 40 CFR 51.308(f)(2)(iii); 2019 Guidance at 31. 

163See 2021 Texas Regional Haze Plan, Response 

to Comments at 472 of 653. 

TABLE 15—TEXAS’s COST ESTIMATES OF NOX CONTROLS FOR EL PASO NATURAL GAS COMPANY CORNUDAS PLANT— 

Continued 

Unit 

NOX

baseline 

emissions 

(tons/yr) 

Control 

Control 

efficiency 

(%) 

NOX

reduction 

(tons/yr) 

5-Year 

life costeffectiveness 

($/ton) 

15-Year 

life costeffectiveness 

($/ton) 

30-Year 

life costeffectiveness 

($/ton) 

Gas Turbine, C2 ................................................ 18 SCR ................. 80 14 129,955 101,694 96,270 

TABLE 16—TEXAS’s COST ESTIMATES OF NOX CONTROLS FOR EL PASO NATURAL GAS COMPANY GUADALUPE

COMPRESSOR STATION

Unit 

NOX

baseline 

emissions 

(tons/yr) 

Control 

Control 

efficiency 

(%) 

NOX

reduction 

(tons/yr) 

5-Year 

life costeffectiveness 

($/ton) 

15-Year 

life costeffectiveness 

($/ton) 

30-Year 

life costeffectiveness 

($/ton) 

Gas Turbine, C–1 .............................................. 56 LNB .................

SCR .................

40 

80 

23 

45 

$13,897 

69,485 

$6,926 

54,975 

$5,588 

52,190 

TABLE 17—TEXAS’s COST ESTIMATES OF NOX CONTROLS FOR GCC PERMIAN ODESSA CEMENT PLANT

Unit 

NOX

baseline 

emissions 

(tons/yr) 

Control 

Control 

efficiency 

(%) 

NOX

reduction 

(tons/yr) 

5-Year 

life costeffectiveness 

($/ton) 

15-Year 

life costeffectiveness 

($/ton) 

30-Year 

life costeffectiveness 

($/ton) 

Cement Kiln No 2 .............................................. 427 LNB ................. 40 171 $3,163 $1,576 $1,272 

i. Texas Did Not Adequately Document 

the Technical Basis and Cost 

Information on Which It Based Its Cost 

of Compliance Analyses as Required by 

the Regional Haze Rule 

Texas did not adequately document 

the technical basis and cost information 

on which it based its evaluation of the 

cost of compliance for all control 

measures considered as required by the 

Regional Haze Rule.155 The SIP 

submittal discusses Texas’s general 

approach for estimating the cost of the 

various control options considered, but 

only provides sum total estimates of the 

capital costs and annual operating and 

maintenance costs without providing 

individual line items or calculations for 

review. Texas received comments 

during the State’s public comment 

period on the proposed Texas RH SIP 

for the second planning period stating 

that the proposed SIP did not include 

proper documentation of the cost 

estimates of the various control 

measures, including the actual 

spreadsheets showing the calculations 

that inform the results of the cost 

analyses as part of the TCEQ’s fourfactor analysis.156 Despite these 

comments, Texas did not directly 

address why calculation spreadsheets 

and other necessary documentation of 

the cost analysis were omitted from the 

proposed SIP, nor did Texas make 

changes to the final SIP submittal or 

include adequate documentation of the 

cost analysis in the final SIP submittal 

in response to these comments. With 

respect to the capital and annual costs 

of scrubber upgrades, Texas provided 

one additional piece of information in 

its response stating that it relied on 

prior studies and work conducted on 

potential scrubbing system upgrades to 

estimate the capital and annual costs to 

inform total annualized costs.157

However, the response does not explain 

what ‘‘prior studies and work conducted 

on potential scrubbing system 

upgrades’’ it relied on or how it relied 

on those studies to estimate the capital 

and annual cost of scrubber upgrades. 

This documentation is critical to 

ensuring that Texas’s consideration of 

cost of potential control measures, as 

required by the RHR and the CAA,158

was reasonable and based on 

sufficiently reliable information.159

The EPA has recommended that costs 

of compliance and the remaining useful 

life should be calculated consistent with 

the methods set forth in the EPA’s 

Control Cost Manual in order to allow 

for comparisons between different 

sources within a State, and cost analyses 

in other states.160 To that end, states 

relying on EPA’s Control Cost Manual 

need only reference the manual as the 

documentation necessary to meet the 

requirements of the RHR to document 

the technical basis, including cost 

information, on which the State is 

relying.161 When a State uses cost 

methods other than the EPA’s Control 

Cost Manual, it is necessary for those 

differences to be reasonable and 

sufficiently documented to meet the 

requirements of the RHR to document 

the technical basis, including cost 

information, on which the State is 

relying.162 In response to comments, 

Texas acknowledged that it deviated 

from EPA’s Control Cost Manual in 

certain instances, but failed to provide 

adequate documentation and 

justification of its costs in light of its 

deviations.163

One important element of a cost 

analysis is the remaining useful life of 


khammond on DSKJM1Z7X2PROD with PROPOSALS2

I I I I I 

I I I I I 

I I I I I 
Federal Register / Vol. 89, No. 199 / Tuesday, October 15, 2024 / Proposed Rules 83361 

164See 2019 Guidance at 33. 

165See 2019 Guidance at 33. 

166Equipment life can depend on the type of 

equipment. For example, the EPA’s Control Cost 

Manual provides for an assumed 30 year equipment 

life for scrubbers, but a 20 year equipment life for 

SNCR. The Control Cost Manual and associated 

spreadsheets are available at https://www.epa.gov/ 

economic-and-cost-analysis-air-pollutionregulations/cost-reports-and-guidance-air-pollution, 

select portions of which are included in the docket 

for this action. 

167 2021 Texas Regional Haze Plan, appendix B at 

B–14—B–15. 

168We are aware that Pirkey and Oklaunion have 

ceased operations. However, the EPA is not aware 

that these permits have been voided. We are also 

aware that other sources such as Coleto Creek and 

Welsh have publicly stated an intention to retire or 

convert to natural gas. Coleto Creek has announced 

its anticipated retirement in 2027 and Welsh has 

announced that it will convert to natural gas by 

2028. These announcements are not an enforceable 

commitment to retire the units by a date certain and 

Texas has not asked to make those retirements 

federally enforceable and permanent by including 

them in the SIP. Therefore, when considering the 

fourth statutory factor, these announcements cannot 

be used to shorten the remaining useful life of the 

sources. See Vistra Announces Plans to Add Up to 

2,000 MW of Gas-Fueled Dispatchable Power in 

ERCOT available at https://investor.vistracorp.com/ 

2024-05-30-Vistra-Announces-Plans-to-Add-Up-to2,000-MW-of-Gas-Fueled-Dispatchable-Power-inERCOT; AEP Schedule of Closures available at 

https://aepcommunitytransition.com/closures/. 

169 2021 Texas Regional Haze Plan, appendix B at 

B–28. 

170 2021 Texas Regional Haze Plan, appendix B at 

B–28. 

171 2021 Texas Regional Haze Plan, appendix B at 

B–28. 

172 2021 Texas Regional Haze Plan, appendix B at 

B–28. The difference in emission reductions 

between SCR and low-NOX burners is 277 tpy. 

173The EPA Air Pollution Control Cost Manual 

(the Control Cost Manual, or Manual), (November 

2017), section 1, Chapter 2 at 16. The Control Cost 

Manual is available at https://www.epa.gov/ 

economic-and-cost-analysis-air-pollutionregulations/cost-reports-and-guidance-air-pollution. 

174We acknowledge that the current bank prime 

rate is higher than the rate at the time Texas 

submitted its SIP, however, at no point has the bank 

prime rate reached 10 percent. A historical record 

of the bank prime rates is available at https://fred.

stlouisfed.org/series/PRIME. Texas’s public 

comment period on the proposed 2021 Texas 

Regional Haze Plan for the second planning period 

took place from October 9, 2020, to January 8, 2021. 

175See Bank Prime Loan Rate Changes: Historical 

Dates of Changes and Rates available at https://fred.

stlouisfed.org/series/PRIME. See also The EPA’s 

Control Cost Manual, section 1, Chapter 2 titled 

‘‘Cost Estimation: Concepts and Methodology,’’ at 

16. 

176A spreadsheet that documents Texas’s cost 

analysis of scrubber upgrades was provided by the 

TCEQ to the EPA at our request during the State’s 

public comment period on the proposed Texas RH 

SIP for the second planning period. However, this 

spreadsheet was not included in the proposed 

Texas RH SIP, nor in the final SIP submitted to the 

Continued 

the equipment. This is important 

because equipment life, while related to 

the ‘‘remaining useful life’’ factor of the 

four-factor analysis, also factors into the 

consideration of cost of compliance due 

to the annualization of cost in 

estimating the cost-effectiveness ($/ton 

reduced). The EPA’s 2019 Guidance 

explains that, generally, states can 

consider the remaining useful life factor 

by considering the useful life of the 

control system.164 Typically, the 

remaining useful life of the source itself 

will be longer than the useful life of the 

emission control system under 

consideration. Thus, annualized costs of 

compliance are typically based on the 

useful life of the control equipment 

rather than the life of the source, unless 

the source is under an enforceable 

requirement to cease operation or 

otherwise reduce its emissions (i.e., 

switching from coal to natural gas).165

The Control Cost Manual generally 

assumes a remaining useful life of 

equipment of 30 years for scrubbers and 

SCR.166 Texas, however, assumed a 

remaining useful equipment life of 15 

years for all sources.167 Texas explained 

that some of the sources it evaluated in 

the four-factor analysis could not 

reasonably be expected to operate an 

additional 30 years,168 but that most 

could reasonably be expected to 

continue to operate longer than five 

years. Therefore, Texas determined that 

a remaining useful life of 15 years was 

a reasonable ‘‘mid-point’’ to use in the 

four-factor analysis. However, Texas did 

not provide any specific documentation 

to support its determination that all of 

the sources it selected could not 

reasonably expected to operate an 

additional 30 years nor did it point to 

any enforceable commitments to retire 

or otherwise reduce its emissions 

contained in the SIP. The selection of a 

15-year useful life inflates the cost of 

controls because those costs are 

amortized over a shorter period of time, 

thereby increasing the calculated 

annualized cost and the costeffectiveness ($/ton reduced). This 

impacted Texas’s identification of costeffective controls and ultimately, their 

assessment of aggregate annualized 

costs. For example, Texas considered 

SCR as a potential NOX control for the 

Texarkana Mill.169 Using a 15-year 

equipment life resulted in an 

annualized capital cost for SCR on 

Boiler No. 2 of $853,383 and a cost 

effectiveness of $5,254 ($/ton).170 Using 

a 30-year equipment life resulted in an 

annualized capital cost of $688,550 and 

a cost effectiveness of $4,956 ($/ton).171

Because Texas used a cost-effectiveness 

threshold of $5,000, Texas did not 

further consider SCR for Boiler No. 2 in 

determining what measures may be 

necessary to include in the long-term 

strategy in order to make reasonable 

progress.172

Another important element of the cost 

analysis is the interest rate used. 

According to the EPA’s Control Cost 

Manual, if a company-specific interest 

rate is not available for use in evaluating 

the cost of controls in the four-factor 

analysis, the use of the current bank 

prime rate is the appropriate default.173

The bank prime rate is reflective of the 

typical rate for borrowing among large 

firms. The bank prime rate was 3.25 

percent for at least six months leading 

up to Texas’s public comment period,174

and remained so when Texas submitted 

the final SIP to the EPA in July 2021.175

Texas instead used a 10 percent interest 

rate, assuming that industrial sources 

could not obtain the bank prime rate. 

However, Texas did not provide any 

documentation to support this general 

assertion. In addition, the use of the 

higher 10 percent interest rate serves to 

increase the total annualized cost. 

Finally, based on Texas’s response to 

comments, Texas included certain costs 

inconsistent with the ‘‘overnight’’ cost 

methodology used in the EPA’s Control 

Cost Manual, which resulted in 

increased costs for the control options 

considered. However, it is unclear from 

the information included in Texas’s SIP 

submission, how and for which sources 

Texas included these costs. In the 

absence of adequate documentation and 

justification to support the basis for its 

cost analysis, we find that Texas’s cost 

analyses are not sufficiently reliable to 

support its control determinations. 

Thus, we find that Texas did not 

adequately document the technical basis 

and cost information on which it based 

its evaluation of the cost of compliance 

of controls, which is a RHR requirement 

under 40 CFR 51.308(f)(2)(iii). Without 

this information, it is unclear how 

Texas’s methodology results in a longterm strategy that includes all measures 

necessary for reasonable progress in the 

Second Planning Period. 

ii. Texas’s Cost Analysis for Scrubber 

Upgrades Was Unsupported and 

Unreasonable 

Texas’s cost analysis of SO2 scrubber 

upgrades for EGUs was unreasonable 

because many assumptions made by 

Texas in estimating the cost of scrubber 

upgrades were inadequately justified 

and based on outlier information that 

led to unreliable and inflated cost 

estimates. As explained in the previous 

section, the 2021 Texas Regional Haze 

Plan did not document or adequately 

explain Texas’s methodology for 

estimating the capital costs and 

operation and maintenance costs of 

scrubber upgrades, which is a 

requirement under 40 CFR 

51.308(f)(2)(iii).176 Rather, the 2021 


khammond on DSKJM1Z7X2PROD with PROPOSALS2
83362 Federal Register / Vol. 89, No. 199 / Tuesday, October 15, 2024 / Proposed Rules 

EPA. Thus, the public did not have an opportunity 

to review or comment on the complete technical 

basis of Texas’s cost analysis of scrubber upgrades. 

We discuss these deficiencies in Texas’s cost 

analysis of scrubber upgrades in greater detail in the 

paragraphs that follow. This spreadsheet is 

included in the docket for this action (scrubber 

upgrades.xlsx). 

177See 2021 Texas Regional Haze Plan, appendix 

B at B–13. 

178The example provided by Texas for estimating 

annual operating and maintenance costs of scrubber 

upgrades is also misleading. For example, Texas’s 

estimated annual operating and maintenance cost of 

scrubber upgrades for AEP Pirkey Unit 1 is 

$2,740,188, as shown in Table 9. This is the 

equivalent of $3.80/kW-year. 

179The only other information Texas provides 

about its scrubber upgrade analysis is in appendix 

B of the 2021 Texas Regional Haze Plan. 

Specifically, Texas includes the following statement 

in discussing the scrubber upgrades analysis for 

AEP Pirkey Unit 1: The Western Regional Air 

Partnership (WRAP) data for potential scrubber 

upgrades and a WRAP spreadsheet from August 

2010 containing data for EGUs with proposed Best 

Available Retrofit Technology SO2 controls were 

relied on for information (also included in the 

docket for this action). The spreadsheet data 

indicated the greatest increase in scrubbing system 

efficiency an existing system could achieve, from 

baseline levels, was 95%. Therefore, the TCEQ 

evaluated a potential system upgrade from 79% to 

95%. See 2021 Texas Regional Haze Plan, appendix 

B at B–4. However, it is unclear based on the 2021 

Texas Regional Haze Plan itself whether the WRAP 

data and spreadsheet were in any way used to 

estimate the capital costs and annual operating and 

maintenance costs of wet scrubber upgrades. 

Furthermore, this statement was only included in 

Texas’s discussion of the scrubber upgrades 

analysis for AEP Pirkey Unit 1 but not specifically 

mentioned in the discussion of scrubber upgrades 

for other EGUs. 180See ‘‘scrubber upgrades.xlsx’’ included in the 

docket for this action. See also, additional source 

specific cost spreadsheets from Texas available in 

the docket for this action. 181 scrubber upgrades.xlsx. 182TCEQ also used the outlier value to estimate 

the cost of upgrading the scrubbers at the Holcim 

cement facility from 90% to 95% control efficiency. 

These costs are also likely an over estimation for the 

same reasons as explained later in this section. 183See ‘‘scrubber upgrades.xlsx’’; see also 2010 

NPS EGUs With Proposed BART SO2 Controls 

Spreadsheet available in the docket. 184 2010 NPS EGUs With Proposed BART SO2

Controls Spreadsheet available in the docket. 

185See Great River Energy Coal Creek BART 

Emission Control Cost Analysis. The report is 

available in the docket for this action. 

186See ‘‘scrubber upgrades.xlsx’’ available in the 

docket for this action. 

187See ‘‘scrubber upgrades.xlsx’’ available in the 

docket for this action. 

188For example, costs to upgrade scrubber 

performance from 94–95% at San Miguel might 

only require increased reagent use, whereas 

scrubber upgrades at less efficient units may require 

more significant equipment upgrades or elimination 

of scrubber bypasses, as demonstrated by the range 

in costs in the NPS dataset. 

189By providing this illustration, the EPA is not 

necessarily endorsing the use of the average capital 

cost to calculate the cost of scrubber upgrades at a 

source. Given the site-specific nature of scrubber 

upgrades, the use of the average capital cost of 

several scrubber upgrades may not accurately 

reflect the cost to upgrade any particular scrubber. 

190See ‘‘EPA modified RH–2021-Summary 

Emissions, Cost Table.xlsx’’ and ‘‘EPA modifiedscrubber upgrades.xlsx’’ spreadsheets. Available in 

the docket for this action. 

Texas Regional Haze Plan merely 

provided an ‘‘example’’ which indicates 

that the average capital cost of wet 

scrubber upgrades is $37.84/kW and the 

average operating and maintenance cost 

is $3.09/kW-year for a 537 MW EGU.177

The significance of the example 

provided in the 2021 Texas Regional 

Haze Plan is unclear. An examination of 

the total capital costs included in the 

2021 Texas Regional Haze Plan reveals 

that Texas did not use an assumption of 

$37.84/kW to estimate capital costs of 

scrubber upgrades, and in fact used a 

cost assumption that was over three 

times higher than the referenced 

‘‘average’’ value. To illustrate, Texas 

estimated the capital cost of scrubber 

upgrades at AEP Pirkey Unit 1 to be 

$99,921,030, as shown in table 9. This 

capital cost estimate is not the 

equivalent of $37.84/kW, but rather 

$138.59/kW. In examining the other 

scrubber upgrades, Texas applied the 

$138.59/kW to all scrubber upgrade 

estimates.178 Thus, the example 

provided by Texas indicating that the 

average capital cost of wet scrubber 

upgrades is $37.84/kW is misleading 

and an inaccurate representation of 

Texas’s methodology for estimating the 

capital cost of wet scrubber upgrades.179

Because Texas did not include 

adequate documentation of its cost 

analysis, the EPA requested additional 

supporting information and data from 

Texas regarding its technical analyses to 

aid in our review. In response to this 

request, the Texas provided additional 

files to the EPA, including Excel 

spreadsheets, that were not made 

available to the public during Texas’s 

public comment period and were not 

included in the final SIP submitted to 

the EPA.180 One of these files is an 

Excel spreadsheet that documents and 

provides additional information on 

Texas’s methodology for estimating the 

capital costs and annual operating and 

maintenance costs of scrubber 

upgrades.181 Reviewing the spreadsheet 

demonstrates Texas’s cost methodology 

relied on certain cost assumptions based 

on outlier information.182

The files documenting the scrubber 

upgrades analysis confirm that Texas 

used an assumption of $139/kW to 

calculate the capital costs of scrubber 

upgrades. This $139/kW assumption is 

the highest capital cost $/kW value out 

of several scrubber upgrades cost 

estimates for EGUs compiled from a 

National Park Service (NPS) spreadsheet 

from 2010 found on the Western 

Regional Air Partnership (WRAP) legacy 

website and relied upon by Texas.183

Furthermore, this $139/kW assumption 

is an outlier value, which corresponds 

to upgrades at the Coal Creek Power 

Plant in North Dakota.184 The costs for 

upgrades at this facility included 

additional project elements other than 

upgrades to the existing scrubber, such 

as coal drying.185 Texas did not explain 

why using cost assumptions from a 

project, which included additional coal 

pre-treatment project costs like coal 

drying, is appropriate or reasonable in 

estimating the capital costs of the 

scrubber upgrades it was considering. 

The next highest capital cost $/kW 

value included in the spreadsheet is an 

upgrade project that was estimated to 

cost $52.39/kW.186 The average $/kW 

capital costs provided in the 

spreadsheet, even including the $139/ 

kW outlier is approximately $38/kW, 

with costs as low as $4/kW for some 

units.187 Scrubber upgrade costs are 

site-specific, depending on existing 

scrubber design and available 

upgrades.188 Therefore, it is 

inappropriate to rely on cost 

assumptions that are based on outliers, 

especially absent any discussion of why 

the higher cost is more reflective of 

upgrades necessary at a particular 

source, because they are not 

representative of the anticipated cost of 

scrubber upgrades at these units. Had 

Texas instead relied on the average 

capital cost found in the spreadsheet, 

and presented as the example 

calculation in its SIP, the capital costs 

contained in the SIP would have been 

significantly lower. 

To illustrate this point, the EPA 

recalculated the scrubber upgrade costs 

for Martin Lake, San Miguel, and Pirkey 

using the average capital cost 189 as well 

as the average operation and 

maintenance costs contained in Texas’s 

Excel spreadsheet and identified in their 

example calculation in appendix B of 

the 2021 Texas Regional Haze Plan.190

EPA focused on these three sources as 

these were the scrubber upgrades that 

Texas identified as meeting its costeffectiveness threshold of $5,000/ton. 

These recalculated values are found in 

table 18. 


khammond on DSKJM1Z7X2PROD with PROPOSALS2
Federal Register / Vol. 89, No. 199 / Tuesday, October 15, 2024 / Proposed Rules 83363 

191See 2021 Texas Regional Haze Plan, appendix 

B, at B–20. 

192We provide additional discussion regarding 

the cost of scrubber upgrades in the TSD for this 

action, provided in the docket. 

193See CAA 169(g)(1); 40 CFR 51.308(f)(2). 

194See CAA 169A(g)(1); 40 CFR 51.308(f)(2)(i). 

195 2021 Texas Regional Haze Plan at 7–13. 

196 2021 Texas Regional Haze Plan at 7–13. 

197 2021 Texas Regional Haze Plan at 7–13. 

198 2021 Texas Regional Haze Plan at 7–13. 

199 2021 Texas Regional Haze Plan at 7–14. 

200See CAA 169A(g)(1); CAA 169A(B)(2)(b). 

TABLE 18—TCEQ VS. EPA RECALCULATED SCRUBBER UPGRADE COSTS

Company/site name Unit 

2018 EIA 

electric 

capacity/2016 

EI capacity 

or engine 

rating 

Capital costs 15 Year life total annual 

cost Emissions 

removed 

(tpy) 

15 year life cost 

effectiveness 

($/ton) 

TCEQ Avg. TCEQ Avg. TCEQ Avg. 

American Electric Power/ 

Pirkey Power Plant.

Unit 1 721 MW ................ $99,921,030 $27,279,969 $15,877,183 $5,817,383 3,874 $4,098 $1,502 

NRG Energy/Limestone 

Elec. Gen. Station.

Unit 1

Unit 2

893 MW ................

957 MW ................

123,757,947 

132,627,498 

33,787,812 

36,209,335 

19,664,805 

21,074,153 

7,205,163 

7,721,546 

3,212 

3,259 

6,123 

6,467 

2,244 

2,370 

Vistra Energy/Martin Lake 

Electrical Station.

Unit 1

Unit 2

Unit 3

793 MW ................

793MW .................

793MW .................

109,899,275 

109,899,275 

109,899,275 

30,004,182 

30,004,182 

30,004,182 

17,462,700 

17,462,700 

17,462,700 

6,398,313 

6,398,313 

6,398,313 

16,172 

14,101 

16,458 

1,080 

1,238 

1,061 

396 

454 

389 

San Miguel Electric Cooperative/San Miguel 

Electric Plant.

Unit 1 410 MW ................ 56,820,558 15,512,881 9,028,634 3,308,081 2,001 4,512 1,653 

Based on this information, and 

utilizing Texas’s selected 15-year 

remaining useful life assumption, the 

15-year total annual costs for scrubber 

upgrades at these three facilities 

decrease from $77,293,916 to 

$28,320,403, a reduction in total annual 

costs of $48,973,513. If the outlier value 

was excluded in determining the 

average capital cost, the total annualized 

costs would be even lower. Thus, the 

reliance on this outlier value in 

estimating the capital costs significantly 

inflates the total annualized costs 

provided in the 2021 Texas Regional 

Haze Plan. Without an explanation as to 

why this was reasonable, this reliance is 

unjustified. Furthermore, had Texas 

used the average capital cost, the costs 

of upgrading the scrubbers at both units 

at Limestone would have been below its 

$5,000/ton cost-threshold. Based on 

Texas’s analysis, upgrading the controls 

on both units at Limestone would result 

in a reduction in over 6,400 191 tpy of 

SO2. The inflation of total annualized 

costs is also important, as discussed 

later in the notice, because Texas relies 

on the combined total annualized costs 

of control measures in part to determine 

that no additional measures are 

necessary to include in its long-term 

strategy to make reasonable progress.192

We are proposing to find that Texas’s 

cost analysis of SO2 scrubber upgrades 

for EGUs does not meet the 

requirements under 40 CFR 

51.308(f)(2)(iii) to document the 

technical basis, including costs, that the 

State is relying on to determine the 

emission reduction measures that are 

necessary to make reasonable progress. 

Furthermore, in estimating the cost of 

scrubber upgrades as part of its fourfactor analysis, many assumptions made 

by Texas were not adequately justified, 

and thus unreasonable, as it resulted in 

inflated and unreliable cost estimates. 

Because of these flaws, we find that 

Texas did not reasonably consider the 

cost of compliance as required by the 

RHR and CAA.193

c. Time Necessary for Compliance 

In its 2021 Regional Haze Plan, 

despite the time necessary for 

compliance being one of the four 

statutory factors a State must consider 

when determining what control 

measures are necessary for reasonable 

progress,194 Texas stated in its 

submission that the time necessary for 

compliance was not a critical factor in 

the determination of applicable 

additional controls for Texas sources.195

That being said, Texas determined that 

the time necessary for a source to 

design, build, and install SO2 scrubbing 

technology would be approximately 

three years and that the time necessary 

to build and commence operation of DSI 

technology could be less given that 

scrubbing vessels would not need to be 

constructed.196 Texas also assumed that 

the time to design, build, and install 

NOX control technologies would be 

approximately three years. While we are 

proposing to disapprove Texas’s longterm strategy for the reasons provided 

elsewhere in Section IV.E of this notice, 

we note that Texas’s assumptions of the 

time necessary for compliance for the 

controls evaluated are reasonable. 

d. Energy and Non-Air Quality 

Environmental Impacts of Compliance 

Where quantifiable for a particular 

control option, energy impacts of 

compliance are reflected in the cost 

estimate and were considered by Texas 

under the cost of compliance factor.197

For instance, electricity costs necessary 

to operate fans, pumps, and other 

ancillary equipment as well as waste 

disposal costs were factored into the 

cost of compliance calculations for dry 

and wet scrubbers, DSI systems, SCR 

systems, and SNCR systems.198 Texas 

stated that control systems that require 

only modifications to alter fuel-air 

mixing and combustion temperatures 

are not expected to have additional 

electricity or steam demands or to 

generate wastewater or solid waste.199

For reasons explained throughout 

section IV.E we are proposing to 

disapprove Texas’s long-term strategy. 

e. Remaining Useful Life 

As we have discussed in detail in 

section IV.E.2.b. of this proposed rule, 

we disagree with Texas’s generalized 

assumption of a 15-year equipment life. 

Without additional discussion 

explaining why the EGUs and non-EGUs 

evaluated in the four-factor analysis 

could not be expected to operate more 

than 15 years or a federally enforceable 

commitment to cease operations or 

otherwise reduce emissions at these 

units within 15 years, Texas’s 

generalized assumption of a 15-year 

equipment life is not reasonable and 

results in the overestimation of the 

annualized capital costs and the costeffectiveness of controls. 

f. Texas’s Control Determinations 

After characterizing the four statutory 

factors, States must consider and weigh 

the factors to determine what control 

measures are necessary to include in its 

long-term strategy to make reasonable 

progress.200 In determining what control 

measures were necessary to make 

reasonable progress, Texas weighed the 

costs of compliance factor and projected 

visibility benefits of potential controls. 

Specifically, Texas relied on both the 

total annualized costs of controls in 


khammond on DSKJM1Z7X2PROD with PROPOSALS2
83364 Federal Register / Vol. 89, No. 199 / Tuesday, October 15, 2024 / Proposed Rules 

201 2021 Texas Regional Haze Plan table 7–4 at 7– 

16 to 7–17. 202 2021 Texas Regional Haze Plan table 7–4 at 7– 

14. 203This table does not reflect NOX costs and 

associated emission reductions from the Oklaunion 

facility. See 2021 Texas Regional Haze Plan at 7– 

15. 204 2021 Texas Regional Haze Plan at 7–14. 205 2021 Texas Regional Haze Plan, appendix A 

at 71–74 of 227. This appendix also provides a table 

that shows which units and control measures were 

included in its sensitivity modeling. While Texas’s 

analysis found that certain control measures at 

Oklaunion Power Station were above its $5,000/ton 

threshold, Texas also included the shutdown of the 

facility in its sensitivity modeling rather than 

potential control measures. 2021 Texas Regional 

Haze Plan at 7–15. 

206See 2021 Texas Regional Haze Plan, Section 

8.5. More general information can be found in 

section 7.2.2.3. 

207Texas refers to this Scenario as ZeroOKU. 

208Texas refers to this Scenario as ZeroOKU&SO2. 

209Texas refers to this Scenario as 

ZeroOKU&SO2&NOX. 

210See 2021 Texas Regional Haze Plan at 8–64. 

211 2021 Texas Regional Haze Plan table 7–6 at 7– 

16. 

212The visibility improvements presented in the 

table reflect Scenario 3. 

considering the costs of compliance, 

which it calculated was over $200 

million, and the ‘‘less than perceptible 

visibility benefit’’ it projected in 

determining that no additional control 

measures were necessary to include in 

its long-term strategy to make 

reasonable progress.201

Texas derived the total annualized 

cost by adding together the annualized 

costs of controls at each source that met 

its $5,000/ton cost effectiveness 

threshold. Table 19 presents a summary 

of the estimated total annualized cost of 

the controls that met Texas’s $5,000/ton 

threshold.202

TABLE 19 203—TEXAS’s POTENTIAL CONTROL STRATEGY SUMMARY

Pollutant Total emissions reductions 

(tons/yr) 

Estimated total 

annualized cost 

NOX ................................................................................................................................ 3,171 $9,335,087 

SO2 ................................................................................................................................ 79,285 195,539,404 

Total Costs ............................................................................................................. .................................................... 204,874,491 

In conjunction with total annualized 

costs, Texas also considered the 

potential visibility benefits of controls 

by conducting three different 

photochemical modeling sensitivity 

runs representing different control 

scenarios. Similar to how it calculated 

the total annualized costs, Texas only 

included those control measures at 

sources for which the cost of the control 

measures met the $5,000/ton threshold 

for NOX or SO2.204 While Texas’s 2021 

Regional Haze Plan did not specifically 

identify (in Chapter 7 or Chapter 8 of its 

SIP) which sources or control measures 

were actually included in the sensitivity 

modeling, the information the TCEQ 

included in PowerPoint presentations 

used for consultation indicates control 

measures for 11 out of the 18 sources 

selected for evaluation under the four 

factor analysis were included in the 

sensitivity modeling.205 Each sensitivity 

scenario reduced NOX and/or SO2

emissions at specific EGU and non-EGU 

sources for the modeled 2028 

scenario.206 Scenario 1 207 involved the 

removal of emissions from the 

Oklaunion Power Station as its owners 

had announced its retirement in 2020. 

Scenario 2 208 included SO2 reductions 

at all units with identified cost-effective 

SO2 controls in addition to Scenario 1. 

Scenario 3 209 included NOX reductions 

at all units with identified cost-effective 

NOX controls in addition to Scenario 2. 

We note that the additional visibility 

improvements provided by the 

inclusion of NOX controls in Scenario 3 

provided little additional visibility 

benefit on the average across the 20 

percent most impaired days, yet the 

associated costs of these controls 

resulted in several millions of dollars 

being included in the total annual costs 

Texas calculated in its 2021 Texas 

Regional Haze Plan.210 The results of 

this modeling analysis were used to 

estimate the overall visibility benefit 

these controls would have on the 20 

percent most impaired days at the Class 

I areas impacted by Texas’s emissions. 

The projected visibility improvements 

at Class I areas impacted by Texas 

sources under Scenario 3 are presented 

in table 20.211

TABLE 20—TEXAS’s ESTIMATED HAZE INDEX IMPROVEMENTS FOR AFFECTED CLASS I AREAS 212

Class I area Haze index improvement 

(dv) 

Big Bend ........................................................................................................................................................................ 0.07 

Caney Creek .................................................................................................................................................................. 0.56 

Guadalupe Mountains .................................................................................................................................................... 0.03 

Salt Creek ...................................................................................................................................................................... 0.07 

Upper Buffalo ................................................................................................................................................................. 0.21 

White Mountain .............................................................................................................................................................. 0.02 

Wichita Mountains ......................................................................................................................................................... 0.23 

Texas ultimately determined that any 

visibility benefit for each Class I area 

would be ‘‘imperceptible.’’ Thus, 

combining the ‘‘imperceptible’’ 

projected visibility benefit for each 

Class I area with the corresponding total 

annual costs associated with the 

controls included in the modeled 

control strategy, Texas concluded that 

no additional control measures were 

necessary to make reasonable progress. 

As discussed below, the EPA finds 

Texas’s conclusion to be unjustified, 

unreasonable, and inconsistent with the 

CAA and the RHR. 

i. Texas’s Consideration of Costs To 

Support Its Determination That No 

Additional Measures Are Necessary To 

Make Reasonable Progress Was 

Unjustified and Unreasonable 

Texas determined that the total 

annualized cost of controls of 


khammond on DSKJM1Z7X2PROD with PROPOSALS2
Federal Register / Vol. 89, No. 199 / Tuesday, October 15, 2024 / Proposed Rules 83365 

213 2019 Guidance at 39. 

214See 2021 Texas Regional Haze Plan at 7–14. 

215See ‘‘EPA modified-RH 2021-Summary 

Emissions, Cost Table.xlsx’’ available in the docket 

for this action. 

216See CAA 169A(g)(1); 40 CFR 51.308(f)(2). 

217 2021 Clarifications Memo at 14; see 2019 

Guidance at 36–37. 

218 2021 Clarifications Memo at 12–13. 

approximately $205 million was too 

high, but provided no context or 

support as to why total annualized cost 

was an appropriate decision metric in 

consideration of the cost of compliance, 

what range of total annualized cost 

would be reasonable, and why $205 

million was not reasonable. While the 

RHR does allow for the evaluation of 

sources on either a source-by-source 

basis or based on the evaluation of 

groups of sources, in almost any case, a 

State could, as Texas has here, aggregate 

the annualized control costs for a large 

number of sources such that the State 

could find the total cost to be ‘‘too 

expensive;’’ and therefore, determine 

that no additional controls are necessary 

to make reasonable progress. This is 

especially true in States like Texas given 

the vast number of sources in the State 

and the number of Class I areas 

impacted by the emissions from these 

sources. Thus, a reasonable source 

selection for a State like Texas would 

necessarily identify several sources for 

evaluation of potential control measures 

for which total annualized costs would 

end up being ‘‘large.’’ Therefore, it is 

unsurprising that Texas found that total 

annualized costs of controls were over 

$200 million; however, without a 

relative scale to compare against, this 

$200 million figure is meaningless and 

does not necessarily support Texas’s 

determination that no control measures 

are necessary for inclusion in its longterm strategy to make reasonable 

progress. This concern is supported by 

EPA’s 2019 Guidance which states that, 

‘‘EPA does not believe it is reasonable 

to solely use a threshold for the capital 

cost or annualized cost to determine 

that a measure is not necessary to make 

reasonable progress. Large capital costs 

considered in isolation may not provide 

complete information about the 

potential reasonableness of a measure 

. . .’’ 213 Furthermore, if this approach 

were replicated in each successive 

planning period, no controls would ever 

be found to be cost-effective and 

necessary to make reasonable progress, 

which would result in no long-term 

strategy. Rather, all that can be 

determined from Texas’s use of the total 

annualized cost is that it represents the 

sum total of the costs of controls for a 

group of sources that impact one or 

more Class I areas in Texas or nearby 

States. Therefore, Texas’s use of total 

annualized cost was unjustified and 

unreasonable. 

In addition to failing to justify how 

consideration of total annualized cost 

was reasonable, Texas also failed to 

explain and justify the apparent 

contradiction between considering 

controls to be cost effective on a source 

specific basis using a threshold of 

$5,000/ton, but then dismissing those 

same controls as too costly when 

presented as total annualized costs. The 

need to support and justify this 

apparent contradiction is critical 

considering that Texas selected its 

$5,000/ton cost effectiveness threshold 

to ‘‘identif[y] the potential control 

measures for each source that could be 

applied in a cost-effective manner,’’ 214

and thus eliminate those control 

measures which they deemed too costly. 

Texas’s reliance on the total annual 

costs of all controls considered cannot 

outweigh or otherwise negate the fact 

these controls were all below Texas’s 

selected cost-effectiveness threshold of 

$5,000/ton. Furthermore, we note that 

the controls that make up this total 

annualized cost have an average $/ton 

cost-effectiveness of less than $2,500/ 

ton SO2 reduced and less than $3,000/ 

ton for NOX reduced. 

Additionally, while the EPA finds 

that Texas’s use of total annualized 

costs was unjustified and unreasonable, 

even if such a metric were appropriate, 

Texas’s total annualized cost of 

approximately $205 million included 

unreasonable costs associated with the 

scrubber upgrades it evaluated. As 

previously explained in section IV.E.2.b, 

Texas’s calculation of the costs 

associated with upgrading the scrubbers 

at Martin Lake, Pirkey, and San Miguel 

used an unsupported outlier value in 

determining the costs, which resulted in 

an inflated cost estimation. Had Texas 

used the average costs rather than the 

outlier value, the total annualized cost 

of the scrubber upgrades would have 

decreased by approximately $49 

million, and the total annualized cost of 

controls would have decreased from 

approximately $205 million to $156 

million.215 Thus, this one decision 

significantly and unreasonably inflates 

the total annualized cost. Even 

assuming the total annualized cost 

metric is a reasonable way of 

considering costs, because Texas failed 

to describe or justify why $205 million 

was too high, and what range of costs 

would be reasonable, we cannot 

determine whether Texas would have 

found this lower total annualized cost 

reasonable such that the measures are 

necessary for inclusion in its long-term 

strategy to make reasonable progress. 

Thus, the EPA finds that Texas failed to 

justify how its use of total annualized 

costs to dismiss controls was reasonable 

and consistent with the CAA and RHR 

requirement to include those measures 

necessary to make reasonable progress 

in its long-term strategy. 

ii. Texas’s Reliance on the Lack of 

Perceptible Visibility Benefits To 

Support Its Determination That No 

Additional Measures Are Necessary Was 

Unreasonable and Inconsistent With the 

CAA and the RHR 

Texas’s determination that visibility 

benefits are only meaningful if it results 

in a perceptible change in visibility was 

unjustified and unreasonable. As 

previously explained, after identifying 

which of the 18 sources selected for 

further analysis using the four statutory 

factors had potential control measures 

meeting the $5,000/ton costeffectiveness threshold for NOX or SO2, 

those emission reductions associated 

with those control measures were then 

included in the photochemical 

modeling sensitivity runs conducted by 

the TCEQ. The projected visibility 

benefits are presented in table 20. 

Because the results of the modeling 

analysis showed that the visibility 

benefit of the modeled control strategy 

for each Class I area fell within a range 

that was ‘‘imperceptible,’’ (which Texas 

defines as less than 1.0 deciview), Texas 

found that this amount of visibility 

improvement was too small to support 

requiring any additional control 

measures for purposes of making 

reasonable progress during this 

planning period. 

The CAA and RHR are clear that the 

four statutory factors must be 

considered when determining the 

enforceable emissions limitations, 

schedules of compliance, or other 

measures that are necessary for 

reasonable progress toward meeting the 

national goal.216 As the EPA has 

previously explained, while visibility 

may be considered along with the four 

statutory factors, it must be done in a 

reasonable way.217 For example, 

visibility modeling can be used to 

compare the visibility benefits of costeffective controls selected through fourfactor analysis to determine which 

controls produce the greatest visibility 

benefits compared to their costs, or 

prioritizing which among several 

sources should install controls during a 

planning period.218 Nowhere in the 

statute or regulations is there a 

requirement that control measures 

produce perceptible visibility 


khammond on DSKJM1Z7X2PROD with PROPOSALS2
83366 Federal Register / Vol. 89, No. 199 / Tuesday, October 15, 2024 / Proposed Rules 

219See CAA 169A(g)(1). 220Responses to Comments on Protection of 

Visibility: Amendments to Requirements for State 

Plans, at pg. 268; Final Rule 82 FR 3078 (Jan. 10, 

2017). The document is available in the following 

docket EPA–HQ–OAR–2015–0531; 2019 Guidance, 

at pg. 38–39. 221 40 CFR 51.301. 222 82 FR 3078, 3093 (Jan. 10, 2017). 223See 2021 Texas Regional Haze Plan, appendix 

F, section 1.2.4. 

224 2021 Texas Regional Haze Plan at 8–52 (‘‘The 

results indicate that for the 13 Class I areas 

evaluated outside of Texas, the Texas influence for 

particulate sulfate is greater than the CIA home 

state influence for nine of the areas, with the largest 

influence ratio for Caney Creek in Arkansas, at 9.27, 

as highlighted in yellow in table 8–41. The Texas 

influence on particulate nitrate is larger for six sites, 

with a maximum ratio of 3.45 for Carlsbad Caverns 

in New Mexico, as highlighted in pink. Six sites 

have a larger Texas influence for both particulate 

sulfate and nitrate: Carlsbad Caverns, Bosque del 

Apache, Salt Creek, and White Mountain in New 

Mexico; and Caney Creek and Upper Buffalo in 

Arkansas.’’). 

225 2021 Texas Regional Haze Plan, appendix F, 

Figure 1–74 at F–75. 

226 2021 Texas Regional Haze Plan table 8–41 at 

8–53. 

227See CAA 169A(a)(1). 

228Responses to Comments on Protection of 

Visibility: Amendments to Requirements for State 

Plans, at 268; Final Rule 82 FR 3078 (Jan. 10, 2017). 

The document is available in the following docket 

EPA–HQ–OAR–2015–0531. 

229 42 U.S.C. 7491(a)(1) (emphasis added). 

improvements to be considered 

necessary to make reasonable progress 

at a particular Class I area; therefore, 

consideration of visibility benefits 

cannot outweigh the results of the 

analysis based on the four factors 

explicitly prescribed in statute.219

Furthermore, if a State uses a visibility 

benefit threshold to evaluate control 

measures, it must explain how its 

approach is consistent with the 

requirement to consider the statutory 

factors in making reasonable progress 

determinations. Texas did not explain 

how the use of perceptibility as a 

threshold to assess visibility benefits is 

consistent with the requirement to make 

reasonable progress. 

Section 169A(a) of the CAA 

establishes as a national goal the 

‘‘prevention of any future, and the 

remedying of any existing, impairment 

of visibility in mandatory Class I 

Federal areas which impairment results 

from manmade air pollution.’’ Nowhere 

in the CAA or the RHR is there a 

requirement to make a minimum 

amount of visibility improvement in 

determining that potential control 

measures are necessary to make 

reasonable progress. Rather, States are to 

make ‘‘reasonable progress’’ towards 

natural visibility conditions every 

planning period. What is necessary for 

reasonable progress, as described 

throughout this section and this notice, 

is determined by a consideration of the 

four statutory factors. To that end, the 

EPA has reiterated that visibility 

thresholds used for BART and other 

analyses in the first planning period 

(e.g., 0.5 deciviews or 1 dv) are, in most 

cases, not appropriate thresholds for 

evaluating the impact of controls for 

reasonable progress in the second 

planning period and beyond.220 This is 

because regional haze is visibility 

impairment that is caused by the 

emission of air pollutants from 

numerous anthropogenic sources 

located over a wide geographic area.221

At any given Class I area, hundreds or 

even thousands of individual sources 

may contribute to regional haze.222 This 

necessarily means that to meet 

Congress’s goal of preventing any future, 

and addressing any existing 

impairment, States must address these 

numerous sources of manmade air 

pollution which cause visibility 

impairment at Class I areas. Given the 

iterative nature of the regional haze 

program, evaluation of control measures 

for relatively smaller sources (with 

commensurate smaller visibility 

benefits) will be needed to continue 

making reasonable progress towards the 

national goal. As such, states should 

consider the magnitude of modeled 

visibility impacts or benefits in the 

context of its own contribution to 

visibility impairment. That is, whether 

a particular visibility impact or change 

is ‘‘meaningful’’ should be assessed in 

the context of the individual state’s 

contribution to visibility impairment. At 

several Class I areas that Texas 

evaluated in its 2021 Regional Haze 

Plan, sulfate was the largest cause of 

anthropogenic visibility impairment, 

with the largest contribution coming 

from Texas anthropogenic sources.223

Texas’s own modeling also showed that, 

for multiple Class I areas, relative to the 

home State in which the Class I area is 

located, Texas’s contribution to sulfate 

concentrations at the Class I area was 

more than the home State itself. For 

example, Texas’s sulfate contribution at 

Caney Creek is nine times the amount 

of Arkansas’s contribution (Texas 

anthropogenic contribution to 

particulate sulfate is 40.81 percent 

compared to Arkansas’s anthropogenic 

contribution of 4.4 percent).224 225 At 

Wichita Mountains, Texas’s sulfate 

contribution is over four times 

Oklahoma’s contribution.226 Yet, by 

using a threshold of perceptibility, 

Texas found that despite these impacts, 

the visibility benefits were too small to 

warrant requiring any additional control 

measures to make progress towards 

reducing this contribution. Such an 

approach is unreasonable as the 

approach results in maintaining 

significant visibility impairment in 

contradiction to Congress’s expressly 

stated goal of remedying manmade 

impairment.227 This concern in part is 

why the EPA has explained that ‘‘the 

existence of an impact above a 

perceptibility threshold is not a 

statutory or regulatory factor to be used 

when determining whether a source or 

sources contribute to visibility 

impairment or when determining 

measures needed for reasonable 

progress.’’ 228 Thus, Texas’s 

determination that the lack of 

perceptible visibility benefits weighed 

in favor of its determination that no 

additional measures were necessary was 

unreasonable and failed to result in a 

long-term strategy that encompassed all 

of the measures necessary to make 

reasonable progress in the second 

planning period. 

Contrary to Texas’s own conclusions, 

the EPA finds that the modeled TCEQ 

control scenarios are projected to 

achieve meaningful reductions in 

impairment. In table 21, based on 

Texas’s own modeling and considering 

visibility impairment using light 

extinction units, the control scenarios 

provide for meaningful progress in 

reducing visibility impairment, 

particularly at Caney Creek. Considering 

just US anthropogenic impairment in 

2028, Texas is responsible for 43 

percent of the total U.S. anthropogenic 

impairment on the 20 percent most 

impaired days at Caney Creek. The 

modeled 3.18 Mm-1 reduction in 

impairment under Texas’s Scenario 2 

represents a 10.6 percent reduction of 

the total US anthropogenic impairment 

in 2028 and 25 percent reduction of the 

Texas contribution to anthropogenic 

impairment. In consideration of the 

statutory goal to remedy ‘‘any existing 

impairment of visibility in mandatory 

Class I Federal area which impairment 

results from manmade air pollution,’’ 229

it is not reasonable to dismiss a 

potential 10.6 percent reduction in the 

nationwide total anthropogenic 

impairment and a 25 percent reduction 

in the Texas contribution to impairment 

as insignificant, especially since Texas 

found all of the modeled controls to be 

below their chosen cost-effectiveness 

threshold of $5,000/ton. 


khammond on DSKJM1Z7X2PROD with PROPOSALS2
Federal Register / Vol. 89, No. 199 / Tuesday, October 15, 2024 / Proposed Rules 83367 

230See ‘‘EPA TX contributions to Class I 

areas.xlsx’’ available in the docket for this action. 

231North Dakota v. EPA, 730 F.3d 750, 764–766 

(8th Cir. 2013) (‘‘Although the State was free to 

employ its own visibility model and to consider 

visibility improvement in its reasonable progress 

determinations, it was not free to do so in a manner 

that was inconsistent with the CAA. Because the 

goal of § 169A is to attain natural visibility 

conditions in mandatory Class I Federal areas, see 

42 U.S.C. 7491(a)(1), and EPA has demonstrated 

that the visibility model used by the State would 

serve instead to maintain current degraded 

conditions, we cannot say that EPA acted in a 

manner that was arbitrary, capricious, or an abuse 

of discretion by disapproving the State’s reasonable 

progress determination based upon its cumulative 

source visibility modeling.’’). 

232See 2019 Guidance at 16, 36. 

233Because improvement in visibility is a nonlinear function of light extinction, focusing on 

visibility improvement in delta deciviews can mask 

the actual progress that can be made in reducing 

impairment by the implementation of controls 

unless visibility improvement is measured against 

clean background conditions. See the TSD in the 

docket for this action for additional discussion of 

background conditions and visibility modeling. 

234See ‘‘SO2 annual emissions by state 2016– 

2022.xlsx’’ spreadsheet available in the docket for 

this action and available on EPA’s CAMPD website, 

https://campd.epa.gov/data/custom-datadownload. 

235See ‘‘Texas annual emissions by facility 

2022.xlsx’’ spreadsheet available in the docket for 

this action, and available on EPA’s CAMPD website 

https://campd.epa.gov/data/custom-datadownload. 236See also CAA 169A(b)(2). 

TABLE 21 230—VISIBILITY BENEFIT OF TEXAS’S CONTROL SCENARIO 2 

Class I area IMPROVE 

monitor 

2028 

extinction 

(Mm-1) 

Texas 

anthro 

(%) 

NonTexas 

U.S. 

anthro 

(%) 

Total 

US 

anthro 

(Mm-1) 

Total 

anthro 

from 

Texas 

(Mm-1) 

Texas % 

of total US 

anthropogenic 

impairment 

Scenario 2 

extinction 

reduction 

(Mm-1) 

Scenario 2 

reduction 

of total 

US 

anthropogenic (%) 

Scenario 2 

reduction 

of Texas 

anthropogenic 

contribution 

(%) 

Scenario 2 

extinction 

reduction 

(dv) 

Scenario 2 

extinction 

reduction 

compared 

to Natural 

conditions 

(dv) 

Caney Creek ... CACR1 55.4 23 31 29.92 12.74 43 ¥3.18 ¥10.60 ¥25.00 ¥0.56 ¥1.32 

Big Bend ......... BIBE1 41.2 10 5 6.18 4.12 67 ¥0.31 ¥5.00 ¥7.50 ¥0.07 ¥0.18 

Upper Buffalo .. UPBU1 53.4 13 38 27.23 6.94 25 ¥1.2 ¥4.40 ¥17.30 ¥0.21 ¥0.48 

Wichita Mountains.WIMO1 53.2 18 33 27.13 9.58 35 ¥1.19 ¥4.40 ¥12.40 ¥0.22 ¥0.61 

HerculesGlades.HEGL1 57.2 9 48 32.60 5.15 16 ¥0.78 ¥2.40 ¥15.20 ¥0.13 ¥0.31 

Salt Creek ....... SACR1 40.3 12 34 18.54 4.84 26 ¥0.27 ¥1.50 ¥5.60 ¥0.06 ¥0.16 

Guadalupe 

Mountains.

GUMO1 34 11 11 7.48 3.74 50 ¥0.1 ¥1.30 ¥2.70 ¥0.03 ¥0.06 

Texas’s consideration of visibility 

benefit is also unreasonable because 

Texas only considered the potential 

visibility benefits relative to ‘‘dirty 

background’’ conditions. Because 

estimates of the visibility benefits of 

emission control measures help guide 

regulatory decisions, relying solely on a 

quantification of visibility benefits 

relative to ‘‘dirty background’’ 231 as 

Texas did in its 2021 Regional Haze 

Plan (i.e., conditions with greater 

impairment than natural background 

visibility conditions) obscures the full 

potential benefits of control measures 

and makes it less likely that a measure, 

or measures, would appear reasonable 

from a visibility benefit perspective.232

Thus, this approach to considering 

visibility benefit serves to maintain the 

current impairment at Class I areas, 

which is inconsistent with the statutory 

goal of the CAA § 169A(a)(1) to 

eliminate future, and remedy existing 

manmade visibility impairment. Texas’s 

own modeling results show that had 

Texas considered the visibility 

improvement associated with the 

control scenarios it modeled relative to 

natural background, the visibility 

improvement would have been 

considerably larger. For example, under 

control Scenario 2, the visibility 

improvement at Caney Creek would be 

considerably larger (1.32 deciviews) 

than the values documented by Texas 

(0.56 deciview).233 The right most 

column in table 21 shows Texas’s 

modeled visibility benefits calculated 

relative to natural visibility conditions. 

Because Texas’s consideration of 

projected visibility benefits was limited 

to a dirty background basis and did not 

consider the full potential benefits 

associated with each control scenario it 

evaluated, Texas’s determination that 

the visibility benefits did not support 

requiring any additional control 

measures was unreasonable. 

Recent annual emissions data from 

EPA’s Clean Air Markets Program Data 

also contradict Texas’s conclusion that 

no controls are needed due to the lack 

of perceptible visibility improvement. 

Across all states, Texas EGU SO2

emissions ranked 1st and has ranked 1st 

over the past several years.234 Within 

the group of sources analyzed by Texas, 

Martin Lake and Coleto Creek ranked 

6th and 31st, respectively, in facilitywide SO2 emissions across the United 

States.235 The magnitude of SO2

emissions from the sources Texas 

included in its sensitivity run, as well 

as all of Texas’s EGUs statewide, is 

demonstrated in the model results 

showing Texas’s large contribution to 

the total U.S anthropogenic visibility 

impairment. This, combined with the 

outcome of the four-factor analyses, 

emphasize that emission reductions 

from additional SO2 controls on the 

sources Texas considered are costeffective would result in meaningful 

progress towards remedying visibility 

impairment from manmade pollution at 

impacted Class I areas. 

Therefore, the EPA finds that Texas’s 

use of perceptibility as a visibility 

threshold to support its decision to 

dismiss controls was unreasonable, 

resulted in an unjustified long-term 

strategy for the second planning period, 

and is inconsistent with the CAA and 

the RHR. 

g. EPA’s Conclusions and Proposed 

Action on Texas’s Four Factor Analysis 

As explained in the preceding 

sections, due to numerous flaws in its 

evaluation of the four-factors and the 

resulting control determinations, Texas 

failed to submit to the EPA a long-term 

strategy that includes ‘‘the enforceable 

emissions limitations, compliance 

schedules, and other measures that are 

necessary to make reasonable progress’’ 

as required by 40 CFR 51.308(f)(2).236

Consequently, the EPA is proposing to 

find that the 2021 Texas Regional Haze 

Plan does not satisfy the requirements of 

40 CFR 51.308(f)(2). 

3. Additional Long-Term Strategy 

Requirements 

Aside from the long-term strategy 

requirements already discussed, States 

must also meet the requirements 

specified in 40 CFR 51.308(f)(2)(ii)-(iv) 

when developing their long-term 

strategies for the second planning 

period. Under 40 CFR 51.308(f)(2)(ii) 

states are required to consult with other 

states that have emissions that are 


khammond on DSKJM1Z7X2PROD with PROPOSALS2
83368 Federal Register / Vol. 89, No. 199 / Tuesday, October 15, 2024 / Proposed Rules 

237 2021 Texas Regional Haze Plan at 8–2. 

reasonably anticipated to contribute to 

visibility impairment in Class I areas to 

develop coordinated emission 

management strategies. Texas included 

documentation of its consultation with 

other states and the FLMs in appendix 

A of its 2021 Regional Haze Plan. 

In addition to our analysis on Section 

51.308(f)(2)(iii) above, this section 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. Texas’s 2021 Texas Regional Haze 

Plan included 2011, 2014, and 2017 

statewide NEI emission data for NOX, 

SO2, PM, VOCs, and NH3. For the base 

case CAMx modeling, Texas also relied 

on 2018 emissions from EPA’s AMPD, 

and 2016 emissions data reported to the 

State of Texas Air Reporting System 

(STARS) database for non-EGU sources. 

Finally, in developing their long-term 

strategies, States must consider five 

additional factors specified under 40 

CFR 51.308(f)(2)(iv). The five additional 

factors are: emission reductions due to 

ongoing air pollution control programs, 

including measures to address 

reasonably attributable visibility 

impairment; measures to mitigate the 

impacts of construction activities; 

source retirement and replacement 

schedules; basic smoke management 

practices for prescribed fire used for 

agricultural and wildland vegetation 

management purposes and smoke 

management programs; and the 

anticipated net effect on visibility due to 

projected changes in point, area, and 

mobile source emissions over the period 

addressed by the long-term strategy. 

Chapter 7 of Texas’s 2021 Regional Haze 

Plan includes a description of these 

additional factors. 

Regardless, as explained in preceding 

sections, due to flaws and omissions in 

its source selection, four-factor analyses, 

and the resulting control 

determinations, we find that Texas 

failed to reasonably ‘‘evaluate and 

determine the emission reduction 

measures that are necessary to make 

reasonable progress’’ by considering the 

four statutory factors as required by 

CAA section 169A(b)(2)(A), CAA 

section 169A(g)(1), and 40 CFR 

51.308(f)(2)(i). We also find that Texas 

failed to adequately document the 

technical basis that it relied upon in 

evaluating potential emissions 

reduction measures, as required by 40 

CFR 51.308(f)(2)(iii). In so doing, the 

EPA finds that Texas failed to submit to 

the EPA a long-term strategy that 

includes ‘‘the enforceable emissions 

limitations, compliance schedules, and 

other measures that are necessary to 

make reasonable progress’’ as required 

by 40 CFR 51.308(f)(2). Consequently, 

the EPA finds that the Texas’s 2021 

Regional Haze Plan does not satisfy the 

long-term strategy requirements of 40 

CFR 51.308(f)(2). Therefore, we are 

proposing to disapprove these 

corresponding portions of Texas’s SIP 

submission. 

F. Reasonable Progress Goals 

Section 51.308(f)(3) contains the 

requirements pertaining to RPGs for 

each Class I area. Texas is host to two 

Class I areas and is therefore subject to 

§ 51.308(f)(3)(i) and, if appliable, to (ii). 

Section 51.308(f)(3)(i) requires a State in 

which a Class I area is located to 

establish RPGs—one each for the most 

impaired and clearest days—reflecting 

the visibility conditions that will be 

achieved at the end of the 

implementation period as a result of the 

emission limitations, compliance 

schedules and other measures required 

under paragraph (f)(2) to be in states’ 

long-term strategies, as well as 

implementation of other CAA 

requirements. The long-term strategies 

as reflected by the RPGs must provide 

for an improvement in visibility on the 

most impaired days relative to the 

baseline period and ensure no 

degradation on the clearest days relative 

to the baseline period. Section 

51.308(f)(3)(ii) applies in circumstances 

in which a Class I area’s RPG for the 

most impaired days represents a slower 

rate of visibility improvement than the 

uniform rate of progress calculated 

under 40 CFR 51.308(f)(1)(vi). Under 

§ 51.308(f)(3)(ii)(A), if the State in which 

a mandatory Class I area is located 

establishes an RPG for the most 

impaired days that provides for a slower 

rate of visibility improvement than the 

URP, the State must demonstrate that 

there are no additional emission 

reduction measures for anthropogenic 

sources or groups of sources in the State 

that would be reasonable to include in 

its long-term strategy. 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. 

Texas established RPGs based on 

projected visibility improvements from 

emission reductions associated with the 

Federal CAA, the Texas Clean Air Act, 

Texas’ ozone SIP revisions and rules, 

and agreements between the EPA and 

petrochemical refineries and carbon 

black manufacturing plants for nitrogen 

oxides (NOX) and sulfur dioxide (SO2) 

emissions reductions. As part of 

establishing the RPGs, the TCEQ 

evaluated the impact of emissions 

reductions from these adopted measures 

on visibility in Class I areas using 

photochemical modeling. Further, the 

TCEQ evaluated the impacts of 

additional controls beyond those 

already adopted using photochemical 

modeling in a sensitivity analysis. Based 

on the results of Texas’s four-factor 

analysis and the sensitivity analysis, the 

TCEQ concluded that additional 

measures for visibility improvement at 

Texas Class I areas and Class I areas 

affected by Texas emissions are not 

reasonable for this planning period. 

The TCEQ elected to perform CAMx 

modeling to develop its future year 

visibility projections to establish its 

reasonable progress goals and evaluate 

the impact of identified emissions 

reductions on visibility in Class I areas. 

The CAMx modeling was based on the 

EPA’s Modeling Guidance and 

consistent with the modeling protocol 

included in appendix G of its SIP 

(Modeling Protocol). The photochemical 

modeling used to support the 2021 

Texas Regional Haze Plan consisted of 

base case model runs, future year model 

runs, including source apportionment 

runs, and three sensitivity runs.237 The 

TCEQ describes the development of its 

emission inventories for use in each 

modeling scenario in appendix E of its 

SIP (Emissions Modeling). 

The TCEQ elected to use the adjusted 

Uniform Rate of Progress (URP) in its 

2021 Regional Haze Plan SIP to evaluate 

its reasonable progress goals. The TCEQ 

presents the visibility for Class I areas 

on the 20% clearest days and 20% most 

impaired days for the 2014–2017 period, 

2028 projected future year, and the 2028 

adjusted glidepath and are shown in 

table 8–43 of its SIP and presented here 

in table 22. 


khammond on DSKJM1Z7X2PROD with PROPOSALS2
Federal Register / Vol. 89, No. 199 / Tuesday, October 15, 2024 / Proposed Rules 83369 

238 2021 Texas Regional Haze Plan at 8–59 to 8– 

60. 239 2021 Texas Regional Haze Plan at 8–52 and 

table 8–41 at 8–53. 240See 2021 Texas Regional Haze Plan, appendix 

F at F–63. 

241The EPA’s visibility protection regulations 

define ‘‘reasonably attributable visibility 

Continued 

TABLE 22—VISIBILITY FOR CLASS I AREAS ON 20% MOST IMPAIRED DAYS AND 20% CLEAREST DAYS

Class I area 

(IMPROVE ID, state) 

2014-2017 

20% clearest 

days 

(dv) 

Future 

year (2028) 

20% 

clearest days 

(dv) 

2028 

adjusted 

glidepath 

(dv) 

Future 

year (2028) 

20% 

most 

impaired days 

(dv) 

Big Bend National Park (N.P.) (BIBE, TX) ........................................................ 5.2 4.9 14.4 14.2 

Bosque del Apache Wilderness Area (W.A.) (BOAP, NM) ............................... 4.6 4.2 9.9 9.6 

Breton Island W.A. (BRIS, LA) .......................................................................... 11.8 11.3 19.8 18.3 

Caney Creek W.A. (CACR, AR) ........................................................................ 8.2 7.8 18.8 17.1 

Great Sand Dunes W.A. (GRSA, CO) .............................................................. 2.9 2.6 8.2 7.3 

Guadalupe Mountains N.P. (GUMO, TX) .......................................................... 4.5 4.1 12.8 12.2 

Hercules-Glades W.A. (HEGL, MO) .................................................................. 9.8 9.1 19.6 17.4 

Mingo W.A. (MING, MO) ................................................................................... 11.2 10.6 20.2 18.6 

Rocky Mountain N.P. (ROMO, CO) .................................................................. 1.3 1.1 9.2 7.3 

Salt Creek W.A. (SACR, NM) ............................................................................ 6.7 6.2 13.5 13.9 

Upper Buffalo W.A. (UPBU, AR) ....................................................................... 8.4 7.9 19.2 16.7 

White Mountain W.A. (WHIT, NM) .................................................................... 2.6 2.2 10 9.5 

Wheeler Peak W.A. (WHPE, NM) ..................................................................... 0.3 0.1 6.5 5.3 

Wichita Mountains W.A. (WIMO, OK) ............................................................... 8.4 7.7 17.4 16.7 

Source: Texas 2021 Regional Haze SIP, Table 8–43. 

Texas included baseline haze indices 

for Big Bend and Guadalupe Mountains 

in Chapter 8 of its 2021 Regional Haze 

Plan. Baseline visibility for the Big Bend 

Class I area is 5.78 dv for the 20% 

clearest days and 15.57 dv for the 20% 

most impaired days. Baseline visibility 

for the Guadalupe Mountains Class I 

area is 5.92 dv for the 20% clearest days 

and 14.60 dv for the 20% most impaired 

days. As Texas notes in its 2021 Texas 

Regional Haze Plan, and as shown in the 

data presented in table 22, the RPGs 

Texas established for both Big Bend and 

Guadalupe Mountains are below the 

adjusted glidepath. 

Texas emissions impact visibility at 

one Class I area, Salt Creek Wilderness 

Area, in New Mexico, that is projected 

to be above the glidepath. Section 

51.308(f)(3)(ii) requires states to 

demonstrate for Class I areas with a 

2028 reasonable progress goal for the 

20% most impaired days above the 2028 

URP that there are no additional 

emission reduction measures for sources 

in the State that would be reasonable to 

include in the long-term strategy. The 

TCEQ states in its 2021 Texas Regional 

Haze Plan that the New Mexico 

Environment Department had not yet 

established a reasonable progress goal 

for Salt Creek Wilderness Area or 

developed its long-term strategy at the 

time Texas prepared its SIP; however 

Texas states that its analysis in the longterm strategy is robust, in accordance 

with 40 CFR 51.308(f)(3)(ii), and that it 

has provided a thorough evaluation of 

the Texas sources that impact Class I 

areas in and around Texas and 

consideration of whether any additional 

emission reduction measures are 

reasonable for the second planning 

period.238

As previously discussed in Section 

IV.E.1, using its source selection 

methodology, Texas did not select any 

sources of SO2 for further evaluation at 

Salt Creek, despite Texas’s PSAT 

modeling showing that Texas sources 

are responsible for almost three times 

the amount of influence due to 

particulate sulfate and more than one 

and half times the influence due to 

particulate nitrate as the home State of 

New Mexico.239 Focusing on modeled 

U.S. anthropogenic impacts alone, 

Texas anthropogenic sources account 

for approximately 51.3% of the 

particulate sulfate concentrations at Salt 

Creek, with more than half of the Texas 

anthropogenic contribution coming 

from Texas EGUs.240 Furthermore, the 

sensitivity modeling Texas conducted 

showed that potential SO2 and NOX

reductions from the aggregate group of 

control measures considered would 

provide for an estimated 0.07 dv 

improvement in visibility at Salt Creek. 

This is despite the fact that only a few 

of the NOX sources included in the 

sensitivity analyses were included 

based on their impact to Salt Creek and 

no SO2 sources were selected based on 

their impact at Salt Creek. The 0.07 dv 

improvement is calculated from a 

reduction in extinction of 0.27 Mm¥1

and represents a 1.5 percent reduction 

of total U.S. anthropogenic contribution 

and a 5.6 percent reduction of Texas’s 

total anthropogenic contribution to 

visibility impairment at Salt Creek. 

While New Mexico had not established 

an RPG for Salt Creek at the time Texas 

submitted its SIP, contrary to its 

assertion, Texas’s analysis did not meet 

the requirements of 51.308(f)(3)(ii)(B) to 

conduct a robust analysis with respect 

to Salt Creek as evidenced by the fact 

Texas did not evaluate sources of SO2

despite PSAT modeling showing the 

substantial impact on the area from 

Texas. 

Under 40 CFR 51.308(f)(3)(iv), the 

EPA must evaluate the demonstrations 

the State developed pursuant to 40 CFR 

51.308(f)(2) to determine whether the 

State’s reasonable progress goals for 

visibility improvement provide for 

reasonable progress towards natural 

visibility conditions. As previously 

explained in section IV.E., we are 

proposing to disapprove Texas’s longterm strategy for failing to meet the 

requirements of 40 CFR 51.308(f)(2). 

Therefore, we also propose to 

disapprove Texas’s reasonable progress 

goals under 40 CFR 51.308(f)(3) because 

compliance with that requirement is 

dependent on compliance with 40 CFR 

51.308(f)(2). 

G. Reasonably Attributable Visibility 

Impairment (RAVI) 

The RHR contains a requirement at 

§ 51.308(f)(4) related to any additional 

monitoring that may be needed to 

address visibility impairment in Class I 

areas from a single source or a small 

group of sources. This is called 

‘‘reasonably attributable visibility 

impairment,’’ 241 also known as RAVI. 


khammond on DSKJM1Z7X2PROD with PROPOSALS2
83370 Federal Register / Vol. 89, No. 199 / Tuesday, October 15, 2024 / Proposed Rules 

impairment’’ as ‘‘visibility impairment that is 

caused by the emission of air pollutants from one, 

or a small number of sources.’’ 40 CFR 51.301. 

242 2021 Texas Regional Haze Plan at 7–17. 

243See 2021 Texas Regional Haze Plan, Chapter 

5 for more information about Texas’s monitoring 

strategy. 

244Spatial and Seasonal Patterns and Temporal 

Variability of Haze and its Constituents in the 

United States Report IV: November 2006 available 

at https://vista.cira.colostate.edu/Improve/spatialand-seasonal-patterns-and-temporal-variability-ofhaze-and-its-constituents-in-the-united-statesreport-iv-november-2006/. 

Under this provision, if the EPA or the 

FLM of an affected Class I area has 

advised a State that additional 

monitoring is needed to assess RAVI, 

the State must include in its SIP 

revision for the second implementation 

period an appropriate strategy for 

evaluating such impairment. The EPA 

has not advised Texas to that effect, and 

the FLMs for the Class I areas that Texas 

contributes to have not identified any 

RAVI from Texas sources.242 For this 

reason, the EPA proposes to approve the 

portions of Texas’s 2021 Regional Haze 

Plan relating to 40 CFR 51.308(f)(4). 

H. 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. Compliance 

with this requirement may be met 

through participation in the Interagency 

Monitoring of Protected Visual 

Environments (IMPROVE) network. 

Texas discusses its monitoring 

strategy in Chapter 5 of its 2021 

Regional Haze Plan. Haze species in 

Texas are measured and analyzed via 

the Interagency Monitoring of Protected 

Visual Environments (IMPROVE) 

network.243 Table 23 of this preamble 

lists the IMPROVE stations representing 

visibility at Texas Class I areas. Due to 

the close proximity of the Class I areas, 

Carlsbad Caverns (New Mexico) and 

Guadalupe Mountains (Texas) share the 

same IMPROVE monitor. 

TABLE 23—IMPROVE STATIONS AT FEDERAL CLASS I AREAS IN TEXAS

Monitor ID Class I area Sponsor Years operated 

BIBE1 .................................................. Big Bend National Park .................................. National Parks Service ...................... 1988–Present. 

GUMO1 ............................................... Guadalupe Mountains National Park ............. National Parks Service ...................... 1988–Present. 

Section 51.308(f)(6)(i) requires SIPs to 

provide for the establishment of any 

additional monitoring sites or 

equipment needed to assess whether 

reasonable progress goals to address 

regional haze for all mandatory Class I 

Federal areas within the State are being 

achieved. 

The IMPROVE program reviewed its 

aerosol monitoring sites in 2006 to set 

priorities for maintaining the sites in the 

event of federal budget cuts affecting the 

IMPROVE program.244 This review 

determined that the IMPROVE aerosol 

samplers at Texas’s two Class I areas 

represent conditions different from the 

conditions at the nearest Class I area 

IMPROVE monitors. Texas’s two Class I 

IMPROVE monitors are not candidates 

for discontinuation since other 

IMPROVE monitors cannot represent 

conditions at Big Bend or Guadalupe 

Mountains. 

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. In its 2021 

Texas Regional Haze Plan, Texas stated 

that future assessments of visibility 

impairment and progress in reducing 

visibility impairment at Texas’s two 

Class I areas, and at Class I areas in 

other states that Texas’s emissions may 

potentially affect, will use the revised 

IMPROVE algorithm and will use data 

as prescribed in the EPA’s Regional 

Haze Rule (40 CFR part 51, subpart P— 

Visibility Protection). The assessment 

will follow, as appropriate, the EPA’s 

guidance including the 2019 Guidance 

and the 2018 Visibility Tracking 

Guidance. 

Section 51.308(f)(6)(iii) does not 

apply to Texas, as it has a Class I area. 

Section 51.308(f)(6)(iv) requires the 

SIP to provide for the reporting of all 

visibility monitoring data to the 

Administrator at least annually for each 

Class I area in the State. As noted above, 

the monitoring strategy for Texas relies 

upon the continued availability of the 

IMPROVE network. The TCEQ does not 

directly collect or handle IMPROVE 

data. The TCEQ will continue to 

participate in the IMPROVE Visibility 

Information Exchange Web System 

(VIEWS). The TCEQ considers VIEWS to 

be a core part of the overall IMPROVE 

program. The TCEQ will report 

IMPROVE data from the two Class I 

areas in Texas to the EPA using the 

VIEWS web system. 

If Texas collects any visibility 

monitoring data through the state’s air 

quality monitoring networks, the TCEQ 

will report those data to the EPA as 

specified under the Performance 

Partnership Grant agreement negotiated 

with the EPA Region 6. All validated 

data and data analysis results from any 

TCEQ visibility-related special studies 

are public information. The TCEQ will 

continue its practice of sharing the data 

and information with the EPA. Texas 

supports the continued operation of the 

IMPROVE network through both State 

and Federal funding mechanisms. 

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. Texas 

provides for emissions inventories and 

estimates for future projected emissions 

by participating in the CenSARA RPO 

and complying with the EPA’s Air 

Emissions Reporting Rule (AERR). In 40 

CFR part 51, subpart A, the AERR 

requires states to submit updated 

emissions inventories for criteria 

pollutants to the EPA’s Emissions 

Inventory System (EIS) every three 

years. The emission inventory data is 

used to develop the NEI, which 

provides for, among other things, a 

triennial state-wide inventory of 

pollutants that are reasonably 

anticipated to cause or contribute to 

visibility impairment. 

Chapter 6 of the 2021 Texas Regional 

Haze Plan includes a discussion of the 

NEI data, and Section 8.3 details 

specific emission inventories and 

emissions inputs developed for the 

regional haze photochemical modeling 


khammond on DSKJM1Z7X2PROD with PROPOSALS2
Federal Register / Vol. 89, No. 199 / Tuesday, October 15, 2024 / Proposed Rules 83371 

conducted by the TCEQ. The source 

categories of the emissions inventories 

included are: (1) point sources, (2) area 

sources, (3) non-road mobile sources, (4) 

drilling rigs, (5) commercial marine 

vessels and locomotives, (6) airports and 

(7) on-road mobile sources. Statewide 

pollutant summaries by source category 

for the years 2011, 2014, and 2017 are 

provided in tables 6–1, 6–2, and 6–3 of 

Texas 2021 Regional Haze Plan. 

Summaries are for the following 

pollutants: SO2, NOX, PM10, PM2.5, 

VOCs, CO, and NH3. Texas also 

provided a summary of anthropogenic 

SO2 and NOX emissions for each source 

type for 2011, 2014, and 2017 and are 

presented in tables 6–4 and 6–5 of the 

2021 Texas Regional Haze Plan. 

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. Texas estimated 2028 

future year emissions by applying 

growth projections and accounting for 

known existing federal, State, and local 

controls. The development of Texas’s 

2028 modeling emissions for the 2021 

Texas Regional Haze Plan includes 

some methods used in previous SIP 

modeling for ozone, such as the Federal 

Tier 3 Vehicle Emission and Fuel 

Standards program, the Mass Emissions 

Cap-and-Trade (MECT) Program in the 

Houston-Galveston-Brazoria area, the 

Highly Reactive VOC Emission Cap-andTrade (HECT) Program in Harris County, 

the Midlothian Cement Kiln caps and 

related agreed orders in the Dallas-Fort 

Worth area, and the EPA’s final CrossState Air Pollution Rule (CSAPR) 

update. Summaries of the primary data 

sources for the development of the 

future case modeling emissions are 

provided in the 2021 Texas Regional 

Haze Plan, appendix E, table 1–4: 

Summary of Future Case Point Source 

Emission Data Sources, table 1–5: 

Summary of Future Case On-Road 

Mobile Source Emission Data Sources, 

and table 1–6: Summary of Future Case 

Non-Road Mobile, Off-Road, Area, Oiland-Gas, and Biogenic Source Emission 

Data Sources. The gridded 

photochemical modeling input files for 

the 2016 and 2028 emissions were 

provided along with the full emission 

processing message log files during 

Texas’s public comment period. For 

point sources, Texas evaluated large 

stationary sources of emissions, such as 

electric generating units (EGUs), 

smelters, industrial boilers, petroleum 

refineries, and manufacturing facilities. 

Point source emissions were developed 

for the January 1 through December 31, 

2016, annual episode with a 2028 future 

year projection. The data sources for 

development of the point source 

modeling emissions are summarized in 

the 2021 Texas Regional Haze Plan, 

appendix E, table 2–1: Sources of Point 

Source Emissions Data. 

The EPA proposes to find that Texas 

has met the requirements of 40 CFR 

51.308(f)(6) as described above, 

including its continued participation in 

the IMPROVE network and the 

CenSARA RPO and its on-going 

compliance with the AERR, and that no 

further elements are necessary at this 

time for Texas to assess and report on 

visibility pursuant to 40 CFR 

51.308(f)(6)(vi). 

In sum, for all the reasons discussed 

in this section, the EPA is proposing to 

approve Texas’s 2021 Regional Haze 

Plan as meeting the requirements of 40 

CFR 51.308(f)(6). 

I. 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. Sections 

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. 

The 2021 Texas Regional Haze Plan 

describes the status of measures of the 

long-term strategy from the first 

implementation period to address the 

requirements found in 40 CFR 

51.308(g)(1) and (2). Control measures to 

reduce emission within and outside the 

State are found in the 2021 Texas 

Regional Haze Plan, Chapter 7: LongTerm Strategy to Establish Reasonable 

Progress Goals, Section 7.4: Federal 

Programs that Reduce Stationary Source 

Emissions, Section 7.5: Federal 

Programs that Reduce Mobile Source 

Emissions, and Section 7.6: State Air 

Pollution Control Programs. Control 

measures in the State are included in 

Section 7.6: State Air Pollution Control 

Programs, which discusses both State 

stationary and mobile source emissions 

control measures; Section 7.6.2: Best 

Available Control Technology (BACT) 

Requirements, which discusses air 

permitting requirements for new and 

modified sources of air pollution; and 

finally Section 7.6.3: Additional 

Measures, which discusses other 

measures addressing air pollution from 

mobile sources, construction activities, 

and fires, and measures addressing 

energy efficiency. Emissions reductions 

are found in the 2021 Texas Regional 

Haze Plan, Chapter 6: Emissions 

Inventory, Section 6.8: NOX and SO2

Emissions Trends, table 6–4: 

Anthropogenic NOX Emissions by 

Source Type, and table 6–5: 

Anthropogenic SO2 Emissions by 

Source Type. 

The EPA proposes to find that Texas 

has addressed the requirements of 40 

CFR 51.308(g)(1) and (2) because the 

2021 Texas Regional Haze Plan 

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) requires that for 

each Class I area within the State, the 

State must assess the following visibility 

conditions and changes, with values for 

most impaired, least impaired and/or 

clearest days as applicable expressed in 

terms of five-year averages of these 

annual values. The 2021 Texas Regional 

Haze Plan includes summaries of 

visibility conditions in Chapter 4: 

Assessment of Baseline and Current 


khammond on DSKJM1Z7X2PROD with PROPOSALS2
83372 Federal Register / Vol. 89, No. 199 / Tuesday, October 15, 2024 / Proposed Rules 

245See 2021 Texas Regional Haze Plan, Section 

6.8. 

246Trends in anthropogenic NOX and SO2

emissions are presented in Figures 6–1 and 6–2 of 

the 2021 Texas Regional Haze Plan, respectively. 

Conditions and Estimate of Natural 

Conditions in Class I Areas, Section 4.2: 

Baseline Visibility Conditions, Section 

4.3: Natural Visibility Conditions. 

Changes in visibility conditions are 

displayed in Chapter 8: Reasonable 

Progress Goals, Section 8.4: Reasonable 

Progress Goal Status. The EPA therefore 

proposes to find that Texas has 

addressed the requirements of 40 CFR 

51.308(g)(3). 

Pursuant to § 51.308(g)(4), Texas 

evaluated emission trends for 

reasonable progress for the 2021 Texas 

Regional Haze Plan and presented those 

data in Chapter 6: Emissions Inventory, 

Section 6.7: Emissions Summaries, table 

6–1: 2011 Statewide Pollutant Summary 

by Source Category, table 6–2: 2014 

Statewide Pollutant Summary by Source 

Category, table 6–3: 2017 Statewide 

Pollutant Summary by Source Category, 

table 6–4: Anthropogenic NOX

Emissions by Source Type, table 6–5: 

Anthropogenic SO2 Emissions by 

Source Type. The EPA is proposing to 

find that Texas has addressed the 

requirements of § 51.308(g)(4) by 

providing emissions information for 

NOX, SO2, PM10, PM2.5, VOCs, and NH3

broken down by type of source. 

Since the 2009 and 2014 Texas 

regional haze SIP revisions, reductions 

in anthropogenic emissions within and 

outside the State have occurred from the 

following: (1) ongoing rules and 

regulations for nonattainment areas in 

Texas (see the 2021 Texas Regional 

Haze Plan Chapter 7: Long-Term 

Strategy to Establish Reasonable 

Progress Goals, Section 7.6: State Air 

Pollution Control Programs); (2) closing 

several major coal-fired plants in Texas, 

which have permanently reduced 

emissions (see Chapter 7, Section 

7.6.3.8: Potential Effects of 

Economically Driven Coal Burning 

Power Plant Closures); (3) continuing 

reductions in mobile emissions through 

the incentives like Texas Emissions 

Reduction Plan (TERP) (see Chapter 7, 

Section 7.6.3.1: Texas Emissions 

Reduction Plan); (4) ongoing energy 

efficiency state-wide, which has 

continued to increase (see Chapter 7, 

Section 7.6.3.3: Energy-Efficiency (EE) 

Programs and Renewable Energy (RE) 

Measures); and other items discussed in 

Chapter 7 of the 2021 Texas Regional 

Haze Plan. Texas uses the emissions 

trend data in the 2021 Texas Regional 

Haze Plan 245 to support the assessment 

that anthropogenic haze-causing 

pollutant emissions in Texas have 

decreased during the reporting period 

and that changes in emissions have not 

limited or impeded progress in reducing 

pollutant emissions and improving 

visibility. Texas’s 2017 emission 

inventories for NOX, SO2, PM10, PM2.5, 

VOCs, and NH3 were lower than their 

2014 emission inventories for those 

same pollutants emissions.246 The EPA 

is proposing to find that Texas has 

addressed the requirements of 

§ 51.308(g)(5). 

In sum, because Texas’s 2021 

Regional Haze Plan addresses the 

requirements of 40 CFR 51.308(g)(1) 

through (5) as required by 40 CFR 

51.308(f)(5), the EPA is proposing to 

approve Texas’s 2021 Texas Regional 

Haze Plan as meeting the requirements 

of 40 CFR 51.308(f)(5) for periodic 

progress reports. 

J. Requirements for State and Federal 

Land Manager Coordination 

Section 169A(d) of the Clean Air Act 

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, 

section 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. 

The TCEQ consulted with the FLMs 

about the impact of Texas’s emissions 

on regional haze at the regional Class I 

areas through conference calls. The 

TCEQ gave a presentation in March 

2020 and discussed impacts to Class I 

areas in the region. An additional 

meeting was held October 8, 2020, 

where NPS presented its evaluation of 

the Texas SIP. NPS requested Texas 

look at 15 additional sources that were 

not included in the TCEQ’s four-factor 

analysis. NPS also requested the TCEQ 

consider impacts to three New Mexico 

Class I areas: Bandelier, Salt Creek, and 

Carlsbad Caverns. NPS also identified 

inconsistencies between the TCEQ’s SIP 

and the CAA. Both the NPS and FS 

submitted comment letters during the 

TCEQ’s public comment period. 

Texas responded to the FLM 

comments and included the responses 

in appendix A of their 2021 Regional 

Haze Plan. Notices of the proposed SIP, 

availability and the public hearing were 

published on TCEQ’s website and in the 

Texas Register, the Fort Worth Star 

Telegram, the Houston Chronicle, the 

Austin American-Statesman, and the El 

Paso Times. A virtual public hearing on 

the proposed SIP revision was held on 

December 8, 2020, and was available for 

participation via internet or phone. 

Written comments relevant to the 

proposal were accepted until the close 

of business January 8, 2021. 

Additionally, Texas’s 2021 Regional 

Haze Plan includes a commitment to 

revise and submit a regional haze SIP by 

July 31, 2028, and every ten years 

thereafter. The state’s commitment 

includes submitting periodic progress 

reports in accordance with 40 CFR 

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). 

Regardless of the consultation 

described above, compliance with 40 

CFR 51.308(i) is dependent on 

compliance with 40 CFR 51.308(f)(2)’s 

long-term strategy provisions and (f)(3)’s 

reasonable progress goals provisions. 

Therefore, because the EPA is proposing 

to disapprove Texas’s long-term strategy 

under 51.308(f)(2) and the reasonable 

progress goals under 51.308(f)(3), the 

EPA is also proposing to disapprove the 

State’s FLM consultation under 

51.308(i). While Texas did take 

administrative steps to provide the 

FLMs the opportunity to review and 

provide feedback on the State’s draft 

regional haze plan, the EPA cannot 

approve that consultation because it was 

based on a plan that does not meet the 

statutory and regulatory requirements of 

the CAA and the RHR, as described in 

this notice of proposed rulemaking. In 

addition, if the EPA finalizes our 

proposed partial approval and partial 


khammond on DSKJM1Z7X2PROD with PROPOSALS2
Federal Register / Vol. 89, No. 199 / Tuesday, October 15, 2024 / Proposed Rules 83373 

247 40 CFR 51.308(f)(5) requires that the second 

planning period SIP revision address the 

requirements listed in (g)(1) through (g)(5). 

248The EJSCREEN tool is available at https://

www.epa.gov/ejscreen. 

249See U.S. Census Bureau Glossary available at 

https://www.census.gov/programs-surveys/ 

geography/about/glossary.html. 

250 In addition, EJSCREEN relies on the five-year 

block group estimates from the U.S. Census 

American Community Survey. The advantage of 

using five-year over single-year estimates is 

increased statistical reliability of the data (i.e., 

lower sampling error), particularly for small 

geographic areas and population groups. More 

information is available at https://www.census.gov/ 

content/dam/Census/library/publications/2020/acs/ 

acs_general_handbook_2020.pdf. 

251See EJSCREEN Environmental Justice 

Mapping and Screening Tool: EJSCREEN Technical 

Documentation for additional information on the 

data and methods used to create the indicators and 

indexes in EJSCREEN, which is available at https:// 

www.epa.gov/ejscreen/technical-information-anddata-downloads. 

disapproval of the 2021 Texas Regional 

Haze Plan, the State (or the EPA in the 

case of a FIP) will be required to again 

complete the FLM consultation 

requirements under 40 CFR 51.308(i). 

Therefore, the EPA proposes to 

disapprove the FLM consultation 

component of the 2021 Texas Regional 

Haze Plan. 

V. Proposed Action 

For the reasons discussed in this 

notice, under CAA section 110(k)(3), the 

EPA is proposing approval of the 

portions of Texas’s 2021 Regional Haze 

Plan relating to 40 CFR 51.308(f)(1): 

calculations of baseline, current, and 

natural visibility conditions, progress to 

date, and the uniform rate of progress; 

40 CFR 51.308(f)(4): reasonably 

attributable visibility impairment; 40 

CFR 51.308(f)(5): 247 progress report 

requirements; and 40 CFR 51.308(f)(6): 

monitoring strategy and other 

implementation plan requirements. The 

EPA is proposing disapproval of the 

remainder of Texas’s 2021 Regional 

Haze Plan, which addresses 40 CFR 

51.308(f)(2): long-term strategy; 40 CFR 

51.308 (f)(3): reasonable progress goals; 

and 40 CFR 51.308(i): FLM consultation. 

VI. Environmental Justice 

Considerations 

Information on Executive Order 12898 

(Federal Actions to Address 

Environmental Justice in Minority 

Populations and Low-Income 

Populations, 59 FR 7629, February 16, 

1994) and how EPA defines 

environmental justice (EJ) can be found 

in the section, below, titled ‘‘VII. 

Statutory and Executive Order 

Reviews.’’ For informational and 

transparency purposes only, the EPA is 

including additional analysis of 

environmental justice associated with 

this proposed action. 

EPA conducted screening analyses 

using EJSCREEN, an environmental 

justice mapping and screening tool that 

provides EPA with a nationally 

consistent dataset and approach for 

combining various environmental and 

demographic indicators.248 The 

EJSCREEN tool presents these indicators 

at a Census block group (CBG) level or 

a larger user-specified ‘‘buffer’’ area that 

covers multiple CBGs.249 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 environmental justice 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).250 To help mitigate 

this uncertainty, we have summarized 

EJSCREEN data within larger ‘‘buffer’’ 

areas covering multiple block groups 

and representing the average resident 

within the buffer areas surrounding the 

sources. We present EJSCREEN 

environmental indicators to 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. These indicators of overall 

pollution burden include estimates of 

ambient particulate matter (PM2.5), 

ozone, nitrogen dioxide, and diesel 

particulate matter 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.251 EJSCREEN 

also provides information on 

demographic indicators, including 

percent low-income, unemployment, 

communities of color, linguistic 

isolation, and education. 

The EPA prepared EJSCREEN reports 

covering a buffer area of approximately 

6-mile radius around each source 

identified in this proposed rulemaking. 

Table 24 presents a summary of results 

from the EPA’s screening-level analysis 

for a few of the areas in Texas compared 

to the U.S. as a whole. The full, detailed 

EJSCREEN report for all areas is 

provided in the docket for this 

rulemaking. 

TABLE 24—EJSCREEN ANALYSIS SUMMARY FOR SOURCES

[see detailed EJSCREEN report for all sources] 

Variables 

Values for buffer areas (radius) for each source and the U.S. 

(percentile within U.S. where indicated) 

Limestone Martin Lake Oklaunion San Miguel U.S. 

Pollution Burden Indicators: 

Particulate matter (PM2.5), annual average ................................................... 8.13 μg/m3

(49%ile) 

8.8 μg/m3

(69%ile) 

6.94 μg/m3

(17%ile) 

8.38 μg/m3

(58%ile) 

8.45 μg/m3

(—) 

Ozone, annual average of the top ten 8-hour daily maximums .................... 61 ppb 

(53%ile) 

56.9 ppb 

(32%ile) 

57.2 ppb 

(33%ile) 

61.7 ppb 

(56%ile) 

61.8 ppb 

(—) 

Nitrogen dioxide, annual average .................................................................. 3.7 ppb 

(11%ile) 

3.2 ppb 

(8%ile) 

3.6 ppb 

(11%ile) 

2.9 ppb 

(6%ile) 

7.8 ppb 

(—) 

Diesel particulate matter ................................................................................ 0.0574 μg/m3

(11%ile) 

0.0572 μg/m3

(11%ile) 

0.0496 μg/m3

(8%ile) 

0.0384 μg/m3

(4%ile) 

0.191 μg/m3

(—) 

Toxic releases to air score * .......................................................................... 320 

(39%ile) 

9400 

(92%ile) 

32 

(14%ile) 

92 

(23%ile) 

4,600 

(—) 

Traffic proximity and volume score * .............................................................. 12,000 

(5%ile) 

9,900 

(4%ile) 

59,000 

(13%ile) 

28,000 

(8%ile) 

1,700,000 

(—) 

Lead paint (percentage pre-1960 housing) ................................................... 0.061% 

(29%ile) 

0.12% 

(38%ile) 

0.51% 

(74%ile) 

0.08% 

(32%ile) 

0.3% 

(—) 

Superfund proximity score * ........................................................................... 0 

(0%ile) 

0.014 

(56%ile) 

0 

(0%ile) 

0 

(0%ile) 

0.39 

(—) 

RMP proximity score * .................................................................................... 0.14 

(39%ile) 

0.18 

(42%ile) 

0.32 

(53%ile) 

0.084 

(30%ile) 

0.57 

(—) 


khammond on DSKJM1Z7X2PROD with PROPOSALS2
83374 Federal Register / Vol. 89, No. 199 / Tuesday, October 15, 2024 / Proposed Rules 

252See Sulfer Dioxide Basics available at https:// 

www.epa.gov/SO2-pollution/sulfurdioxide-basics

#effect. 

253See Health and Environmental Effects: 

Particulate Matter available at https://www.epa.gov/ 

pm-pollution/healthand-environmental-effectsparticulate-matter-pm. 

TABLE 24—EJSCREEN ANALYSIS SUMMARY FOR SOURCES—Continued 

[see detailed EJSCREEN report for all sources] 

Variables 

Values for buffer areas (radius) for each source and the U.S. 

(percentile within U.S. where indicated) 

Limestone Martin Lake Oklaunion San Miguel U.S. 

Hazardous waste proximity score * ................................................................ 0.058 

(15%ile) 

0.055 

(15%ile) 

0 

(0%ile) 

0 

(0%ile) 

3.5 

(—) 

Underground storage tank proximity score * ................................................. 0.022 

(29%ile) 

0.18 

(36%ile) 

0.11 

(34%ile) 

0.000039 

(26%ile) 

3.6 

(—) 

Wastewater discharge score * ....................................................................... 52 

(50%ile) 

50 

(49%ile) 

0.35 

(18%ile) 

14 

(38%ile) 

700,000 

(—) 

Drinking water noncompliance, points ........................................................... 2.7 

(87%ile) 

9.9 

(92%ile) 

2.2 

(87%ile) 

0.86 

(77%ile) 

2.2 

(—) 

Demographic Indicators: 

People of color population ............................................................................. 21% 

(37%ile) 

33% 

(51%ile) 

43% 

(60%ile) 

44% 

(61%ile) 

40% 

(—) 

Low-income population .................................................................................. 33% 

(60%ile) 

28% 

(52%ile) 

41% 

(72%ile) 

15% 

(29%ile) 

30% 

(—) 

Unemployment rate ........................................................................................ 3% 

(45%ile) 

4% 

(55%ile) 

5% 

(62%ile) 

9% 

(79%ile) 

6% 

(—) 

Linguistically isolated population ................................................................... 1% 

(59%ile) 

0% 

(56%ile) 

4% 

(71%ile) 

0% 

(57%ile) 

5% 

(—) 

Population with less than high school education .......................................... 11% 

(60%ile) 

8% 

(50%ile) 

30% 

(91%ile) 

29% 

(91%ile) 

11% 

(—) 

Population under 5 years of age ................................................................... 4% 

(47%ile) 

9% 

(80%ile) 

5% 

(54%ile) 

0% 

(13%ile) 

5% 

(—) 

Population over 64 years of age ................................................................... 27% 

(83%ile) 

17% 

(53%ile) 

17% 

(55%ile) 

35% 

(92%ile) 

18% 

(—) 

* The traffic proximity and volume indicator is a score calculated by daily traffic count divided by distance in meters to the road. The Superfund proximity, RMP 

proximity, and hazardous waste proximity indicators are all scores calculated by site or facility counts divided by distance in kilometers. The underground storage tank 

proximity indicator is the weighted count within a 1,500-foot block group. The toxic releases to air indicator is the modeled toxicity-weighted concentration. The wastewater discharge indicator is the modeled toxicity-weighted concentrations divided by distance in meters. 

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 SO2.252 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.253 This action, 

which proposes to partially approve and 

partially disapprove the Texas Regional 

Haze SIP submitted on July 20, 2021, 

will not directly result in a change to 

emissions or air quality if finalized. 

Further, there is no information in the 

record indicating that this proposed 

action, if finalized, would have 

disproportionately high or adverse 

human health or environmental effects 

on communities with environmental 

justice concerns. 

VII. 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 partially approve 

and partially disapprove State law as 

meeting or not meeting Federal 

requirements and does not impose 

additional requirements beyond those 

imposed by State law. 

Additional information about these 

statutes and Executive Orders can be 

found at https://www.epa.gov/lawsregulations/laws-and-executive-orders. 

A. Executive Order 12866: Regulatory 

Planning and Review, Executive Order 

13563: Improving Regulation and 

Regulatory Review, and Executive Order 

14094: Modernizing Regulatory Review 

This action is not a significant 

regulatory action as defined in 

Executive Order 12866 (58 FR 51735, 

October 4, 1993), as amended by 

Executive Order 14094 (88 FR 21879, 

April 11, 2023), and was therefore not 

subject to a requirement for Executive 

Order 12866 review. 

B. Paperwork Reduction Act (PRA) 

This action does not impose an 

information collection burden under the 

PRA (44 U.S.C. 3501 et seq.) because it 

does not contain any information 

collection activities. 

C. Regulatory Flexibility Act (RFA) 

This action is certified to not have a 

significant economic impact on a 

substantial number of small entities 

under the RFA (5 U.S.C. 601 et seq.). 

This action will not impose any 

requirements on small entities beyond 

those imposed by State law. 

D. Unfunded Mandates Reform Act 

(UMRA) 

This action does not contain any 

unfunded mandate as described in 

UMRA, 2 U.S.C. 1531–1538, and does 

not significantly or uniquely affect small 

governments. This action imposes no 

enforceable duty on any State, local, or 

Tribal governments or the private sector. 

E. Executive Order 13132: Federalism 

This action does not have federalism 

implications as specified in Executive 

Order 13132 (64 FR 43255, August 10, 

1999). It will not have substantial direct 

effects on the states, on the relationship 

between the national government and 

the states, or on the distribution of 

power and responsibilities among the 

various levels of government. 


khammond on DSKJM1Z7X2PROD with PROPOSALS2
Federal Register / Vol. 89, No. 199 / Tuesday, October 15, 2024 / Proposed Rules 83375 

F. Executive Order 13175: Coordination 

With Indian Tribal Governments 

In addition, this proposed rulemaking 

action, pertaining to Texas regional haze 

SIP submission for the second planning 

period, does not 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). 

G. Executive Order 13045: Protection of 

Children From Environmental Health 

Risks and Safety Risks 

EPA interprets Executive Order 13045 

(62 FR 19885, April 23, 1997) as 

applying only to those regulatory 

actions that concern environmental 

health or safety risks that EPA has 

reason to believe may 

disproportionately affect children, per 

the definitions of ‘‘covered regulatory 

action’’ in section 2–202 of the 

Executive Order. Therefore, this action 

is not subject to Executive Order 13045 

because it merely proposes to partially 

approve and partially disapprove a SIP 

revision as meeting federal 

requirements. Furthermore, the EPA’s 

Policy on Children’s Health does not 

apply to this action. 

H. Executive Order 13211: Actions That 

Significantly Affect Energy Supply, 

Distribution, or Use 

This action is not subject to Executive 

Order 13211 (66 FR 28355, May 22, 

2001), because it is not a significant 

regulatory action under Executive Order 

12866. 

I. National Technology Transfer and 

Advancement Act (NTTAA) 

Section 12(d) of the NTTAA directs 

the EPA to use voluntary consensus 

standards in its regulatory activities 

unless to do so would be inconsistent 

with applicable law or otherwise 

impractical. This action is not subject to 

the requirements of section 12(d) of the 

NTTAA (15 U.S.C. 272 note) because 

application of those requirements would 

be inconsistent with the CAA. 

J. Executive Order 12898: Federal 

Actions To Address Environmental 

Justice in Minority Populations and 

Low-Income Population 

Executive Order 12898 (Federal 

Actions To Address Environmental 

Justice in Minority Populations and 

Low-Income Populations, 59 FR 7629, 

Feb. 16, 1994) directs Federal agencies 

to identify and address 

‘‘disproportionately high and adverse 

human health or environmental effects’’ 

of their actions on communities with 

environmental justice (EJ) concerns to 

the greatest extent practicable and 

permitted by law. The EPA defines 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.’’ 

The State did not evaluate 

environmental justice considerations as 

part of its SIP submittals; 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, if finalized, this 

action is expected to have a neutral 

impact on the air quality of the affected 

area. 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 E.O. 12898 of 

achieving environmental justice for 

communities with EJ concerns. 

List of Subjects in 40 CFR Part 52 

Environmental protection, Air 

pollution control, Nitrogen dioxide, 

Ozone, Particulate matter, Sulfur oxides. 

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

Dated: September 27, 2024. 

Earthea Nance, 

Regional Administrator, Region 6. 

[FR Doc. 2024–23341 Filed 10–10–24; 8:45 am] 

BILLING CODE 6560–50–P 


khammond on DSKJM1Z7X2PROD with PROPOSALS2