UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

APR 16 2013 

Ms. Kathleen Waylett 

Senior Deputy Attorney General 

Environmental Division 

North Carolina Department of Justice 

P.O. Box629 

Raleigh, North Carolina 27602-0629 

Ms. Sheila C. Holman 

Director, Division of Air Quality 

North Carolina Department of 

Environment and Natural Resources 

1641 Mail Service Center 

Raleigh, North Carolina 27699-1641 

Re: 	 North Carolina's Implementation of Visibility Impact Assessment Requirements for New 

Major Stationary Sources and Major Modifications Subject to Clean Air Act Prevention 

of Significant Deterioration Requirements 

Dear Ms. Waylett and Ms. Holman: 

This is in response to the enclosed March 20, 2012, letter from then-Senior Deputy James Gulick to 

Brian Doster ofthe U.S. Environmental Protection Agency's Office of General Counsel (OGC) 

summarizing North Carolina's understanding of the EPA's views regarding the evaluation of the 

visibility impacts of new and modified sources on Class I areas under the Clean Air Act's Prevention of 

Significant Deterioration (PSD) permitting program. It followed the enclosed March 9, 2011 letter from 

Beverly Bannister, Director of the EPA Region 4 Air, Pesticides and Toxics Division to Sheila Holman, 

Director of the Division of Air Quality of the North Carolina Department of Environment and Natural 

Resources and the enclosed August 19, 2011 letter from Mr. Gulick to David Coursen of OGC. The 

March 20, 2012 letter requested that the EPA review North Carolina's summary and determine whether 

it accurately describes the EPA's position on the legal basis for requiring a comparison to natural 

visibility conditions in determining whether emissions from a new or modified source will cause 

visibility impairment in a Class I area. In addition, the letter requested confirmation that North 

Carolina's summary accurately identifies the main elements of the two-step process necessary to 

determine whether any visibility impacts rise to the ievel of an "adverse impact on visibility," which the 

EPA described at our February 23, 2012, meeting with representatives from your office, the North 

Internet Address (URL) http://www.epa.gov 
 

Recycled/Recyclable o Printed with Vegetable Oil Based Inks on 100% Postconsumer, Process Chlorine Free Recycled Paper 
 
Carolina Division of Air Quality (NC DAQ), the U.S. Fish and Wildlife Service, and the U.S. Forest 

Service. The March 2012 letter accurately summarizes the key components of the EPA's interpretation, 

but the EPA is not in complete agreement with some of the details reflected in the letter's summary. We 

clarify the EPA's views on these topics below. 

The EPA agrees that North Carolina's summary accurately describes the substance of the "two-step 

process" for determining whether a new or modified major stationary source that may affect visibility 

will cause an "adverse impact on visibility." The first step requires an assessment of visibility 

impairment based on how visibility would change from what would have existed in the absence of any 

human-caused pollution, and this analysis must be provided to the appropriate Federal Land Manager(s) 

regardless of whether the Class I increment is exceeded. The EPA also agrees that the second step in the 

analysis, the determination of whether the source will have an adverse impact on visibility, requires a 

more holistic evaluation of various factors affecting visibility, potentially including current visibility 

conditions and whether the State is on track toward improving visibility. 

The. above interpretation is consistent with North Carolina's state implementation plan (SIP)-approved 

regulations. Specifically, 15A NCAC 2D .0530, 1 provides that: (a) finding a "visibility impairment" is a 

prerequisite to finding an "adverse impact on visibility;"2 (b) the visibility analysis the State provides to 

the Federal Land Manager( s) must assess whether the proposed new or modified source will cause 

"visibility impairment;"3 (c) "visibility impairment" refers to "any change in visibility ... from that 

which would have existed under natural conditions;" and (d) "natural conditions" includes "naturally 

occurring phenomena that reduce visibility" (and necessarily excludes human-caused factors impacting 

visibility such as pollution from existing industrial sources). Because North Carolina's SIP already 

incorporates by reference the key federal regulatory provisions underlyingthe EPA's interpretation, it is 

not necessary for North Carolina to revise its SIP to meet PSD visibility requirements. Moreover, 

applying the EPA's interpretation of the visibility impact assessment requirements would not in any 

respect make North Carolina's requirements more restrictive than federallaw.4 

The EPA also wishes to clarify its views on two topics discussed in North Carolina's letter. First, the 

EPA does not view the discussion of "natural conditions" in its 1999 Federal Register notice as 

clarifying existing regulations, but instead as reiterating what already was clear from the plain language 

ofthe federal regulations. See 64 Fed. Reg. 35714,35728/2 (July 1, 1999) (explaining that "[n]atural 

1 See North Carolina SIP rule 15A NCAC 2D .0530(b) (incorporating by reference the federal 

definitions at 40 C.F.R. § 51.301; 51 Fed. Reg. 2695, 2695 (Jan. 21, 1986) (stating that the federal 

definitions of "adverse impact on visibility" and "visibility impairment" are incorporated into the North 

Carolina SIP). 

2 See 40 C.F.R. § 51.301 (defining "adverse impact on visibility," as "visibility impairment which 

interferes with the management, protection, preservation, or enjoyment of the visitor's visual experience 

ofthe Federal Class I area") (emphasis added). 

3 Because a source cannot be found to have an "adverse impact on visibility" unless the source's 

anticipated emissions would cause "visibility impairment," the analysis provided to the Federal Land 

Manager(s) pursuant to 40 C.F.R. § 51.307(a)(l) must demonstrate whether the proposed source would 

cause a "visibility impairment." See also North Carolina SIP rule 15A NCAC 2D .0530(q)(3) (providing 

that the visibility impact analysis provided to the Federal Land Manager(s) should indicate whether the 

source may cause "visibility impairment"). 

4 See Letter from James C. Gulick, North Carolina Department of Justice (NC DOJ), to David Coursen, 

U.S. EPA Office of General Counsel, dated August 19,2011, at 5. 

2 
conditions" are "the visibility conditions that would be experienced in the absence of human-caused 

impairment"). Second, while North Carolina's letter recognizes that the factors listed in the definition of 

"natural conditions" at 40 C.F.R. § 51.301 are "not exhaustive," and the EPA believes that there may be 

additional "natural" factors that would affect visibility under "natural conditions," the definition of 

"natural conditions" cannot be extended to include unnatural factors such as pre-existing visibility 

impairment caused by industrial sources. 

Further, under 15A NCAC 2D .0530(q)5

, it is North Carolina's obligation to identify proposed new or 

modified sources that may affect visibility in a Class I area, and to provide the Federal Land Manager(s) 

with timely notice of such proposed sources along with the required visibility analysis. This obligation 

reflects the EPA regulations requiring that a state PSD implementation plan provide for "[w]ritten 

notification of all affected Federal Land Manager(s) of any proposed new major stationary source or 

modification that may affect visibility in any Class I area," that must "include an analysis of the 

anticipated impacts on visibility in [the] Class I area." 40 C.F.R. § 51.307(a)(l). Such notification 

reflects the statutory and regulatory recognition that "[t]he Federal Land Manager and the Federal 

official charged with direct responsibility for management" of Class I lands" "have an affirmative 

responsibility to protect the air quality related values (including visibility) of any such lands within a 

class I area .... " 42 U.S.C. § 7475(d)(2)(B); 40 C.F.R.§ 51.166(p); see also 40 C.F.R. Part 51, Appendix 

W. The EPA strongly encourages North Carolina to work directly with the Federal Land Manager(s) to 

establish mutually agreeable and effective procedures for both notifying the Federal Land Manager(s) of 

those sources that may affect visibility and administering the visibility impact assessment requirements 

in the manner described above. 

The EPA appreciates the time that NC DOJ and NC DAQ have invested in addressing the EPA's 

concerns rega,rding North Carolina's implementation of the PSD Class I visibility impact assessment 

requirements. If the North Carolina Department of Environment and Natural Resources (NCDENR) has 

any further questions, please feel free to contact Beverly Banister, Director of the EPA Region 4's Air, 

Pesticides and Toxics Management Division, at (404) 562-9326. 

Sincerely, 

Director 

Air, Pesticides and Toxics Management Division 

U.S. Environmental Protection Agency, Region 4 

5 North Carolina has requested that the EPA approve a newer version of this regulation as part ofNorth 

Carolina's SIP, but the EPA has not yet granted approval. The new version of the regulation (stateeffective date January 2, 2011) includes substantially the same regulatory language at 15A NCAC 2D 

.0530(t). 

3 
~Mane Wood 

Director, Air Quality Policy Division 

Office of Air Quality Planning and Standards 

U.S. Environmental Protection Agency 

Brian Doster, Esq. 

Assistant General Counsel 

Office of General Counsel 

U.S. Environmental Protection Agency 

Enclosure(s) 

cc: Mr. Stephen T. Smith, Chairman 

Environmental Management Commission, NCDENR 

Ms. Sandra Silva, Chief '

Branch of Air Quality '

U.S. Fish Wildlife Service '

Mr. Bret Anderson '

U.S. Forest Service '

4 '
State of North Carolina 

Department of Justice Sender's Contact lnfonnation: ROY COOPER 

P.O.BOX 629 James C. Gulick 

ATTORNEY GENERAL jgulick@ncdoj.gov RALEIGH, NC 27602-0629 (919) 716-6940 

August 19, 2011 

VIA EMAIL (coursen.david@epa.gov) and USPS 

David F. Coursen 

Office of General Counsel 

USEP A Headquarters 

Ariel Rios Building 

1200 Pennsylvania Avenue, N. W. 

Mail Code: 2322A 

Washington, DC 20460 

Re: Modeling impacts to Class I areas for PSD permits 

Dear Mr. Coursen: 

On March 9, 2011, Sheila Holman, the Director of North Carolina's 

Division of Air Quality, received the attached letter from Ms. Beverly H. Banister 

at Region 4. The letter discusses modeling procedures under the Prevention of 

Significant Deterioration ("PSD") program regarding Class 1 areas. The timing of 

this letter was unfortunate, as it was received one business day prior to the 

Environmental Management Commission's consideration of the issue in a 

particular contested case. However, my larger concern is that the letter appears to 

conflict with prior EPA rulemaking and EPA's earlier approvals of the North 

Carolina approach. To our knowledge, the letter represents the first and only 

statement by EPA setting out this new interpretation of federal requirements .with 

respect to Class 1 areas. 

I write to you in an effort to clarify North Carolina's position and seek 

EPA's assistance to resolve this matter. The matter, of course, concerns modeling 

by which the "Federal Land Manager [may] demonstrate[] to the satisfaction of the 

State" that a new or modified source ''will have an adverse impact on the air 

quality-related values (including visibility)" of any Class 1 areas. Clean Air Act 

§165(d)(2)(D)(ii), 42 U.S.C. 7475(d)(2)(C)(ii). Specifically, should the impacts of 
David F. Coursen 

August 19, 2011 

Page 2 of6 

the modeled source be measured against existing air quality conditions ("existing 

background") or against an ideal, "natural" baseline ("natural background")? 

At the suggestion of Stan Meiburg, Deputy Administrator of Region 4, last 

week I had a telephone conversation on this subject with Vera Kornylak and Keri 

Powell in the Regional Counsel's office at Region 4. In that conversation, Ms. 

Powell indicated that the views expressed in Ms. Banister's letter were the 

considered views of EPA headquarters. Following the conversation, I asked for a 

contact at EPA Headquarters with whom I could discuss the matter and she 

suggested that I contact you, as you were involved in preparation of the March 9 

letter. As you are on vacation until August 26th and I will be on vacation from 

August 25 to September 8th, I thought it would be helpful to summarize my 

thoughts in a letter to you so you can be considering them before we talk. 

During my conversation with Region 4, I was told that the March 9 letter 

reflects EPA's view that the plain language of the federal rules requires the use of 

natural background for Class 1 PSD modeling. (In other words, impacts should be 

compared to circumstances in which only "natural conditions" impact visibility.) 

We respectfully disagree; until now, EPA's consistent interpretation, in formally 

promulgated rules, has been just the opposite. EPA's previous positions would 

have to be changed, if at all, by a formal rule-making. Ms. Banister's letter cannot 

override a consistent history of formal pronouncements. See NRDC v. EPA, 643 

F.3d 311 (D.C. Cir. 2011). . 

Ms. Banister's letter (p. 2) asserts that under the plain language of EPA's 

rules, particularly 40 C.F.R. §§51.301 and 51.307, ''the required assessment of a 

proposed new or modified source's visibility impacts must involve an analysis of 

how the project's emissions would impact natural conditions." As Ms. Banister 

observes, "'natural conditions' is defined as 'naturally occurring phenomena that 

reduce visibility as measured in terms of light extinction, visual range, contrast, or 

coloration"' (quoting 40 C.F .R. §51.30 1 (definition of "natural conditions")). 

North Carolina agrees, as Ms. Banister notes, that modeling must assess the 

"humanly perceptible change in visibility (light extinction, visual range, contrast, 

coloration) from that which would have existed under natural conditions." 40 

C.F.R. §5.1.301 (definition of ''visibility impairment"). That is to say, modeling 

must account for "naturally occurring phenomena" such as humidity and ambient 

light conditions, ''that reduce visibility." 
David F. Coursen 

August 19, 2011 

Page 3 of6 

But the question with which we are confronted is not whether "natural 

conditions" such as humidity and ambient light levels must be considered, but to 

what extent emissions from other anthropogenic sources are to be considered. The 

rule text cited in Ms. Banister's letter does not address the latter issue. 

Nevertheless, on that question EPA's rules are also clear: Visibility modeling 

under the PSD permitting program must include existing background conditions as 

encumbered by current manmade pollutant loadings including other permitted 

sources. 

In 1985, EPA promulgated a final rule designed to "implement the existing 

new source review arid consultation requirements in §51.307" and "not ... to 

modify these requirements or the definitions in §51.301 associated with them." 

State Implementation Plans for Visibility New Source Review Monitoring 

Strategy, 50 Fed. Reg. 28,544, 28,547 (1985). There, EPA stated plainly that "[i]n 

assessing a proposed source's impact on visibility, the reviewing authority must 

necessarily review that impact in the context of existing background visibility. 

This point does not seem debatable." /d. at 28,548 (emphasis added). During my 

conversation with Ms. Powell, she asserted that North Carolina took this statement 

out of context. We disagree. EPA concluded the same paragraph of the rule with 

this statement: "The EPA concludes that the proposed language on assessing 

whether a proposed source will cause an adverse impact on visibility requires the 

reviewing authority to review the new source's impact in the context of 

background visibility impacts caused by both existing and previously permitted 

sources. /d. (emphasis added). 

Moreover, in a later, separate rulemaking, EPA reiterated this conclusion: 

"[A]n assessment of whether a proposed source would cause an adverse impact on 

visibility requires the permitting authority to review the new source's impact in 

the context of background impacts caused by both existing and previously 

permitted (not yet constructed) sources." Prevention of Significant Deterioration 

(PSD) and Nonattainment New Source Review (NSR), 61 Fed. Reg. 38,249, 

38,284 n.57 (1986) (citing 45 Fed. Reg. at 28,548). 

Most particularly, on January 21, 1986, EPA by rule approved North 

Carolina's proposed SIP changes to implement the required consultation with 

Federal Land Managers regarding impacts to Class 1 areas, and to provide for 

visibility monitoring in the context of making permit decisions. In that formally 

promulgated rule, EPA stated: 
David F. Coursen 

August 19, 2011 

Page 4 of6 

The visibility monitoring program meets the criteria for an approvable 

. plan, as it will provide the State with reliable background visibility 

data for making permit decisions and for assessing visibility trends. 

It has been reviewed and been found to meet the provisions contained 

in 40 CFR 51.305. 

The Weather Service provides visibility measurements in units of 

distance, or visual range, which are recorded three times a day for 

every day of the year. This data is appropriate for use in modeling 

potential visibility impacts of new sources .... 

[Existing] National Weather Service Stations . . should provide 

acceptable regional background data to use in making visibility 

related permit decisions .... The State will use this visibility data 

in making fits} permit decisions. 

Approval Promulgation of Implementation Plans; N.C. Visibility SIP, 51 Fed. 

Reg. 2695, 2696 (1986) (emphasis added). This rule shows EPA's specific intent 

and understanding that North Carolina use existing conditions gleaned from 

current monitoring data in permitting decisions. Together, these formal documents 

unmistakably. evidence EPA's considered opinion that existing background 

visibility data are to be used to evaluate impacts to visibility when issuing permits 

under the PSD program. 

Further, EPA's Guidelines on Air Quality Models - another formally 

promulgated authority - indicates that "[b ]ackground air quality includes pollutant 

concentrations due to: (1) Natural sources; (2) nearby sources other than the one(s) 

currently under consideration; and (3) unidentified sources." 40 C.F .R. Part 51, 

Appx. W, §8.2.1 (July 1, 2010). Finally, EPA's Interagency Workgroup on Air 

Quality Modeling Phase 2 Summary Report and Recommendations for Modeling 

Long Range Transport Impacts (Dec. 1998) ("IW AQM"), also eschews the use of 

natural background. Instead, it allows for "estimates of background visibility 

conditions at Class I areas" to be "derived from the IMPROVE (Interagency 

Monitoring of PRotected Visual Environments) network." /d. at 27. IWAQM 

establishes background as "the average of the cleanest 20% of the data from 

IMPROVE" at a given site. But IW AQM recognizes that although it refers to 
David F. Coursen 

August 19, 2011 

Page 5 of6 

these data as "clean conditions," they are not indicative of a natural background 

because "[ e ]ven the data from the cleanest days usually exhibit some made-made 

influence." !d. 

These authorities point unerringly to the use of existing background data in 

the modeling of source impacts to Class 1 areas under the PSD program. North 

Carolina has adhered to these authorities, including the recommendation in 

IWAQM to use "the average of the cleanest 20% of the data," and does not require 

the use of natural background. We believe this is consistent with EPA's historical 

and longstanding reading of its own rules. 

For all the foregoing reasons, North Carolina respectfully disagrees with 

EPA's assertion that its rules, as written, plainly require the use of natural 

background. EPA's position appears out of step with the range of authorities 

discussed above. 

Before this summer, the Environmental Management Commission 

("EMC")- North Carolina's air quality rulemaking body- could have decided to 

alter North Carolina's rules to require the use of natural background for PSD 

modeling purposes regardless of whether the views expressed in the Banister letter 

are correct or not. There has recently been at least some support for requiring the 

use of natural background expressed by some EMC members. Such a change 

would have resolved the conflict without the need to clarify the basis for EPA's 

recent interpretation further. However, new North Carolina legislation, enacted just 

this summer over the Governor's veto, puts new restrictions on adoption of state 

environmental rules that are "more restrictive" than EPA rules on the same subject. 

2011 N.C. Sess. Laws 398, §2 (codified in relevant part at N.C. Gen. Stat. §150B19.3). This makes it vital that we resolve this matter. 

Therefore, I request that you review these matters again. I would appreciate 

the opportunity for further discussion to get a better understanding of EPA's legal 

position and also to see if there is a way to resolve this matter to allow North 

Carolina to determine the best path forward in compliance with the requirements of 

the Clean Air Act, EPA's regulations and North Carolina's rules. I look forward to 

discussing this with you after September 8, 2011. 
. 
 

David F: Coursen 

August 19, 2011 

Page 6 of6 

Sincerely, 

s/ James C. Gulick 

James C. Gulick 

Senior Deputy Attorney General 

Copies: Vera Kornylak, EPA Region 4 

Keri Powell, EPA Region 4 

Sheila Holman, NC DAQ 
REPLYTO: State of North Carolina JAMES C. GULICK 

ENVIRONMENTAL DIVISION ROY COOPER Department of Justice PHONE: 919.716.6940 

ATTORNEY GENERAL PO BOX 629 FAX: 919.716.6767 

RALEIGH, NORTH CAROLINA E-MAIL: JGULICK@NCDOJ.GOV 

27602-0629 

March 20, 2012 

Brian Doster, Esq. 

Office of General Counsel 

US EPA Headquarters VIA EMAIL (doster.brian@epa.gov) and USPS 

Ariel Rios Building 

1200 Pennsylvania Avenue, N.W. 

Mail Code: 2322A 

Washington, DC 20460 

Re: Modeling impacts to Class I areas for PSD permits 

Dear Brian: 

Our meeting on February 23, 2012 was very helpful. Thank you for your 

help. The purpose of this letter, as we discussed, is to summarize North Carolina's 

understanding of EPA's position with regard to the evaluation of the visibility 

impacts of new sources in Class I areas under the PSD permitting program. This 

summary is not intended necessarily to represent DAQ's agreement with any 

particular EPA position or statement. 

We would appreciate your review of our summary to determine whether it 

accurately summarizes EPA's positions, first, on the legal basis for requiring a 

comparison to natural background in determining visibility impairment, and, 

second, with regard to describing the main elements of the two-step process 

necessary to complete the PSD visibility review that EPA described at our meeting. 
• '

Brian Doster, Esq., Office of General Counsel, US EPA 

March 20, 2012 

Page 2 

Summary of EPA's View of Legal Requirement for 

Comparison Against Natural Background in Determining Visibility 

Impairment" 

The definition of "visibility impairment," read in the context of the 

statutory goal,l necessarily requires a comparison of the source's emissions against 

natural background: 

Visibility impairment means any humanly perceptible change in 

visibility (light extinction, visual range, contrast, coloration) from that 

which would have existed under natural conditions. 

40 CFR § 51.301. 

The te.rm "natural conditions" is defined in the rules as including naturally 

occurring phenomena such as light extinction, visual range, contrast, or coloration. 

However, the definition of the term is not exhaustive: 

Natural conditions includes naturally occurring phenomena that 

reduce visibility as measured in terms of light extinction, visual range, 

contrast, or coloration. 

40 CFR § 51.301 (emphasis added). EPA believes that its 1999 rulemaking 

concerning the regional haze program clarified that "natural conditions" as used in 

the definition of "visibility impairment" means natural background (which includes 

naturally occurring phenomena). 

A plain reading of the definition of "adverse impact on visibility'' 

demonstrates that a finding of "visibility impairment" must be made prior to a 

finding of adverse impact: 

Adverse impact on visibility means, for purposes of section 307, 

visibility impairment which interferes with the management, 

protection, preservation, or enjoyment of the visitor's visual experience 

of the Federal Class I area. This determination must be made on a 

case-by-case basis taking into account the geographic extent, intensity, 

duration, frequency and time of visibility impairments, and how these 

factors correlate with (1) times of visitor use of the Federal Class I 

1 The statutory goal is "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." 42 U.S.C. § 7491(a)(l). 
Brian Doster, Esq., Office of General Counsel, US EPA 

March 20, 2012 

Page 3 

area, and (2) the frequency and timing of natural conditions that 

reduce visibility. This term does not include effects on integral vistas. 

40 CFR § 51.301 (emphasis added). The term "visibility impairment" precedes the 

other considerations in the rule. Thus, in order to find that an adverse impact 

exists, there must be a threshold finding of "visibility impairment." 

Summary of EPA's Two Step Process 

Step 1 - Is there "visibility impairment"? 

The first step in the PSD visibility inquiry is determining whether there is a 

"visibility impairment" as defined in 40 C.F.R. § 51.301. In making this 

determination, the proposed source's visibility impacts must be compared to the 

visibility in the Class 1 area in the absence of any man-made pollution, or, as North 

Carolina has referred to it, "natural background."2 This determination must be 

made and provided to the FLM regardless of whether the increment is exceeded. 

If there is no visibility impairment, the applicant does not need to proceed 

further, because there can be no "adverse impact" without visibility impairment. 

Step 2 - Is there an adverse impact on visibility? 

If there is a finding of visibility impairment, it must then be determined 

whether that impairment "interferes with the management, protection, 

preservation, or enjoyment of the visitor's visual experience of the Federal Class I 

area," such that there is an adverse impact on visibility Id. § 51.301. This process 

involves taking a more holistic approach. In determining whether the visibility 

impairment rises to the level of an adverse impact on visibility, the FLM will then 

consider a number of factors potentially including current conditions, and whether 

the State is on the "glide path" toward improved visibility. This is a case-by-case 

evaluation.s 

Here, cumulative impacts and the State's regional haze SIP, progress and 

planned progress toward the statutory goal may be considered. For example, 

where, as part of a larger emissions reduction program, a proposed new source will 

2 Beverly Banister's March 9, 20llletter to Sheila Holman indicates that the impacts of the 

proposed source on a Class I area are for permitting purposes to be "compared against what visibility 

would be in [the] Class I area under natural conditions." 

3 Additionally, an understanding of the degree or intensity of any visibility impairment, while not 

dispositive, assists in evaluating whether there is an adverse impact on visibility. 
Brian Doster, Esq., Office of General Counsel, US EPA 

March 20, 2012 

Page 4 

be replacing older, more polluting sources such that there will be a net reduction in 

emissions, this net reduction would be considered in evaluating whether there is 

any adverse impact on visibility. 

EPA's March 9 letter (at p. 2) indicates that current visibility conditions 

"may" be relevant to the FLM's determination of visibility impacts. Neither the 

statute nor EPA's rules require the FLM to consider "current visibility'' conditions. 

However, current visibility conditions are properly considered by the FLM or the 

State in order to evaluate whether the visibility impairment "interferes with the 

management, protection, preservation, or enjoyment of the visitor's visual 

experience of the Federal Class I area." 

The preambles to EPA's rulemakings in 1985 said, for example, that "[i]n 

assessing a proposed source's impact on visibility, the reviewing authority must 

necessarily review that impact in the context of existing background visibility." 

This language reflects EPA's view that under the second step it is appropriate, if 

not necessary as a practical matter, for the reviewing State to consider current 

conditions in evaluating adverse impact. Thus, even if the FLM does not consider 

current conditions, the State can find that it is not satisfied by the FLM's decision 

and base its own determination as to whether the proposed source will have an 

"adverse impact on visibility" at least in part on its consideration of the proposed 

source's visibility impacts in light of current conditions.4 

With regard to the adverse impact analysis and determination, the burden 

shifts between DAQ and the FLM depending on whether increment analysis shows 

that the increment is exceeded. See CAA § 165(d), 42 U.S.C. § 7475(d). 

(a) If the increment is not exceeded, the burden is on the FLM to demonstrate 

that there is an adverse impact. If DAQ disagrees with the FLM, DAQ 

can still issue the permit. Of course, DAQ's action must be consistent with 

applicable administrative law principles governing review of agency 

decisions. 

(b) If the increment is exceeded, the burden is on the owner or operator or the 

State to convince the FLM that there is no adverse impact. If the FLM 

concurs, then DAQ may issue the permit. 

4 NC's understanding is that EPA does not believe that it would be correct to aggregate all manmade 

emissions, including those from the proposed source, and compare the aggregate result together to 

natural background. This would not fulfill the statutory and regulatory mandate to determine the 

visibility impacts of "such facility." See, e.g., 42 U.S.C. §7475(d)(2)(C)(ii). 
Brian Doster, Esq., Office of General Counsel, US EPA 

March 20, 2012 

Page 5 

Sincerely, 

Is 

James C. Gulick 

Senior Deputy Attorney General 

C: 	 David F. Coursen, EPA Headquarters 

Vera Kornylak, EPA Region 4 

Keri Powell, EPA Region 4 

Sheila Holman, NC DAQ 
. 

Brian Doster, Esq., Office of General Counsel, US EPA 

March 20, 2012 

Page 6