Air Pollution Control District Of Jefferson County, Kentucky v. United States Environmental Protection Agency

The Air Pollution Control District of Jefferson County, Kentucky, seeks review of an order of the Environmental Protection Agency ("EPA"), reported at 47 Fed.Reg. 6624 (Feb. 16, 1982). That order denied Jefferson County's petition for interstate pollution abatement, filed pursuant to section 126 of the Clean Air Act, 42 U.S.C. Sec. 7426(b) (Supp. V 1981). Jefferson County sought relief upon its claim that the Gallagher Power Station ("Gallagher") in southern Indiana emits air pollutants in violation of section 110 of the Act, 42 U.S.C. Sec. 7410(a)(2)(E)(i) (Supp. V 1981).1 In that connection, Jefferson County sought a reduction of sulfur dioxide ("SO2 ") emissions from the Gallagher generator. The County claimed that Gallagher's SO2 emissions violated the provisions of the Clean Air Act which prohibit emissions in one state that prevent the attainment or maintenance of national ambient air quality standards ("NAAQSs") in another state. Id. Jefferson County also maintained that Gallagher's emissions interfered with the margin for future industrial growth that the County had sought to create by placing strict controls on the emission of SO2 by Kentucky sources.

The EPA denied Jefferson County's section 126 petition for interstate pollution abatement because it found that Gallagher did not "substantially contribute" to the violation of NAAQSs in Jefferson County.

The procedural and substantive issues now raised by Jefferson County are (a) whether the EPA complied with the procedures required by the Clean Air Act in its consideration of Jefferson County's section 126 petition, (b) whether the EPA employed the correct criteria in its computer modeling studies of the impact of Gallagher's emissions, (c) whether 42 U.S.C. Sec. 7601 creates a substantive requirement of regional uniformity in emission standards, (d) whether 42 U.S.C. Sec. 7410(a)(2)(E) requires that a polluting state must "substantially contribute" to a NAAQS violation in another state before the interstate pollution abatement provisions are triggered, and (e) whether 42 U.S.C. Sec. 7410 forbids Gallagher's present emissions even though they are permissible under Indiana's state implementation plan ("SIP") as revised and approved by the EPA. This latter claim is based upon Jefferson County's assertion that section 126 provides a remedy where Gallagher, although not in violation of Indiana's SIP, nonetheless threatens the margin for growth which the County has sought to create.

I. The Clean Air Act.

Passage of the Clean Air Act ("Act"), 42 U.S.C. Secs. 7401-7642 (Supp. V 1981),2 substantially increased federal involvement in national air pollution control and at the same time preserved a strong reliance upon state involvement and responsibility. See generally 1 Grad, Treatise on Environmental Law, Sec. 2.03 (1984). The Act directs the Administrator of the EPA to identify and establish air quality standards for pollutants which are harmful to the public welfare. 42 U.S.C. Sec. 7408. That done, the Administrator is required to set primary and secondary NAAQSs3 for those pollutants. 42 U.S.C. Sec. 7409.

In obedience to the statutory mandate, the EPA has set primary and secondary NAAQSs for various pollutants, including sulfur dioxide. 40 C.F.R. Secs. 50.4-.5 (1982). Under the statutory scheme, responsibility for implementing the NAAQSs set by the Administrator then passes to the various states. Each state is required by the Act to devise, adopt and submit to the Administrator for approval a SIP for enforcing the NAAQSs. 42 U.S.C. Sec. 7410(a)(1). Once a state submits its SIP, the Administrator must approve the plan if it meets eleven criteria specified in the Act. 42 U.S.C. Sec. 7410(a)(2)-(3). These criteria include establishment of emission limitations, timetables for compliance with those limitations, provisions for monitoring air quality, and a program to enforce the emission limitations. 42 U.S.C. Sec. 7410(a)(2)(A)-(K). If a state fails to submit a satisfactory plan, the Administrator must devise a plan for the state. 42 U.S.C. Sec. 7410(c)(1).

Once a SIP is approved, the state must meet the primary NAAQSs within three years, and attain secondary NAAQSs within a "reasonable" time. 42 U.S.C. Sec. 7410(a)(2)(A).4 Areas which achieve the NAAQSs are subject to the regulations of Part C of the Act. 42 U.S.C. Secs. 7470-91. Part C is designed to prevent significant deterioration ("PSD") in the air quality of regions which meet the NAAQSs. Part C establishes maximum "increments" by which increased emissions of SO2 can exceed "baseline" concentrations of that pollutant. 42 U.S.C. Sec. 7473. Consequently, in an area where the air is cleaner than the NAAQSs require, Part C permits specified incremental increases in the emission of SO2 so long as maximum allowable concentrations of that pollutant are not exceeded. Id.

Areas which do not achieve the NAAQSs are designated as "nonattainment areas" and are subject to the regulations of Part D of the Act. 42 U.S.C. Secs. 7501-08. Part D requires stringent emission limitations to insure compliance with NAAQSs as quickly as possible. Again, like Sec. 7410 of the Act, Part D relies primarily on the state to implement a satisfactory "non-attainment" plan. 42 U.S.C. Sec. 7502. In this respect, the Clean Air Act has been described as "a bold experiment in cooperative federalism," Connecticut v. EPA, 696 F.2d 147, 151 (2d Cir.1982): the EPA identifies the end to be achieved, while the states choose the particular means for realizing that end.

Nevertheless, the Act has generated much intergovernmental friction. Critics claim that the state-oriented structure of the Act ignores the realities of air pollution. Since any state's air at a given moment is at best transient, or in bureaucratic terms, "ambient," air pollution in one state inevitably affects the quality of air in surrounding states. Congress acknowledged that the 1970 version of the Act had proved "an inadequate answer to the problem of interstate air pollution" and in 1977 amended the Act to deal specifically with interstate pollution abatement. H.R.Rep. No. 294, 95th Cong., 1st Sess. 329-31, reprinted in 1977 U.S.Code Cong. & Ad.News 1077, 1408-10. The Act, as now amended, provides that to approve any SIP or revision thereto, the Administrator must determine that:

(E) [The SIP] contains adequate provisions (i) prohibiting any stationary source within the State from emitting any air pollutant in amounts which will (I) prevent attainment or maintenance by any other State of any such national primary or secondary ambient air quality standard, or (II) interfere with measures required to be included in the applicable implementation plan for any other State under Part C of this subchapter to prevent significant deterioration of air quality or to protect visibility, and (ii) insuring compliance with the requirements of section 7426 of this title, relating to interstate pollution abatement ....

42 U.S.C. Sec. 7410(a)(2)(E). Under section 126 of the Act, 42 U.S.C. Sec. 7426(b), any state or political subdivision may petition the Administrator for a finding that a major source violates the prohibition of section 7410(a)(2)(E)(i). Jefferson County filed such a section 126 petition with the EPA in these proceedings.

However, neither the Act nor its legislative history defines when the emission of a pollutant in one state will be deemed by the Administrator to "prevent attainment or maintenance" of the NAAQSs by another state. This uncertainty provides the basis for the present controversy.

II. Regulatory Background and Proceedings Before the EPA.

Jefferson County, Kentucky, and Floyd County, Indiana, share a common boundary on the Ohio River. The City of Louisville is located in the northwest portion of populous Jefferson County. In contrast, Floyd County is relatively undeveloped. However, since Jefferson County and Floyd County draw on the same air resources, they, along with Clark County, Indiana, were designated by the EPA as the Louisville Interstate Air Quality Control Region.5 40 C.F.R. Sec. 81.35 (1982).

Because the structure of the Clean Air Act is state-oriented, each state is charged with implementing national clean air standards within its own political boundaries. Thus, although Floyd County and Jefferson County are in the same air quality control region, each county is subject to the implementation plan adopted by its respective state. Initially this was not a problem, since Indiana and Kentucky had adopted identical emission limitations for the pollutant at issue in this case, SO2 .

On May 14, 1973, EPA approved Indiana's SIP for Floyd County. This regulatory scheme set an emission limitation for the Gallagher Power Station of 1.2 pounds of SO2 per million British Thermal Units ("lbs/MBTU") of heat input. Gallagher is situated less than a mile from the Indiana-Kentucky border and is the largest producer of SO2 in Floyd County. In 1972, the EPA had approved Kentucky's SIP which set emission limitations of 1.2 lbs/MBTU of SO2 for the major sources in Jefferson County: three power plants owned by Louisville Gas and Electric.

This uniformity of emission limitations in Floyd County and Jefferson County did not last long. In 1974, Indiana adopted new SO2 regulations for Floyd County that completely exempted Gallagher from the 1.2 lbs/MBTU emission limitation, though the plant was required to keep on hand a two week supply of low-sulfur fuel should atmospheric conditions require lower SO2 emissions. At first the EPA proposed to disapprove Indiana's regulation. However, when Indiana submitted technical data which showed that exempting Gallagher from limitations on the emission of SO2 would not interfere with the attainment and maintenance of SO2 standards in either Indiana or Kentucky, the EPA approved the regulation. 41 Red.Reg. 35,676 (Aug. 24, 1976). In 1979, Indiana submitted a revision of the SO2 portion of its SIP to the Agency. The new plan established an emission limitation for SO2 of 6 lbs/MBTU heat input for most Indiana power plants, including Gallagher. This 6 lbs/MBTU limitation represents the amount of SO2 currently emitted by the Gallagher plant without any controls; thus, the new "limitation" effectively maintains the status quo of uncontrolled SO2 emission at Gallagher. On May 26, 1982, EPA proposed to approve the 6 lbs/MBTU limit with respect to the primary NAAQSs in Floyd County, but to disapprove it as to the secondary NAAQS. 47 Fed.Reg. 22,976.

Meanwhile, in Jefferson County the 1.2 lbs/MBTU emission limitation was generally enforced. In 1975 Louisville Gas and Electric negotiated consent orders whereby final compliance with the 1.2 lbs/MBTU limitation would be delayed until 1985. However, even with strict emission limitations, Jefferson County has yet to attain the NAAQSs for SO2 , and on February 23, 1978, Jefferson County was designated a Part D non-attainment area for both primary and secondary standards. 43 Fed.Reg. 8964 (Mar. 3, 1978); 40 C.F.R. Sec. 81.318 (1983).

It can therefore be seen that a significant disparity exists between the permissible emission limits of power plants in Jefferson County, Kentucky, and the Gallagher plant in Floyd County, Indiana. Louisville Gas and Electric, the primary producer of SO2 in Jefferson County, spent approximately $138 million installing scrubbers to remove SO2 from its emissions, while across the river, Gallagher's SO2 emissions were completely uncontrolled.

On May 14, 1979, the Air Pollution Control District of Jefferson County filed a petition for interstate pollution abatement under section 126 of the Clean Air Act, 42 U.S.C. Sec. 7426. The petition requested that EPA find (1) that SO2 emissions from Gallagher are preventing attainment and maintenance of the NAAQSs for SO2 in Jefferson County and (2) that once Jefferson County attains the NAAQSs for SO2 , Gallagher's emissions will interfere with Jefferson County's efforts to prevent significant deterioration of air quality under Part C of the Act. The petition sought tighter controls on Gallagher's SO2 emissions.

In response to Jefferson County's section 126 petition, EPA commissioned a computer dispersion modeling study6 to determine the effect of Gallagher's SO2 emissions on the air in Jefferson County. After the modeling study was completed, EPA held a public hearing regarding the section 126 petition on April 17, 1980, and accepted comments from interested parties until September 3, 1980. In its notice of the hearing, EPA suggested various interstate pollution issues which commentators might address. 45 Fed.Reg. 17,048 (Mar. 17, 1980). Following the hearing, EPA failed to render a decision on the petition despite a statutory requirement that a final decision be made within 60 days. 42 U.S.C. Sec. 7426(b). On December 31, 1980, Jefferson County filed suit in federal district court to compel EPA to either grant or deny the section 126 petition. On May 21, 1981, the district court ordered EPA to make a decision within 60 days.

After doing additional computer modeling studies, the EPA, ostensibly to comply with the court order, proposed on July 30, 1981 to deny Jefferson County's section 126 petition. 46 Fed.Reg. 38,937. The EPA stated that Gallagher's uncontrolled SO2 emissions neither cause nor substantially contribute to violations of the SO2 NAAQSs in Kentucky. Id. According to the EPA modeling studies, Gallagher would contribute approximately three percent to those SO2 concentrations in Jefferson County which violated the SO2 NAAQSs. The EPA also rejected Jefferson County's argument that, once the NAAQSs for SO2 were achieved, Gallagher's emissions would interfere with Jefferson County's measures under Part C of the Act to prevent significant deterioration. The EPA stated that it need not consider such potential effects because no PSD measures currently apply to Jefferson County; it was of no consequence, in EPA's view, whether Gallagher might contribute to violations of future PSD measures. In its proposed notice of denial, the EPA published three new criteria for evaluating future section 126 petitions. It acknowledged that Jefferson County had addressed these criteria at the hearing. Id.7

Thereafter, Jefferson County submitted comments on EPA's proposed denial of the section 126 petition and on the three new criteria. The County disputed several of the factors used by the EPA and conducted its own modeling study, submitting the results to the EPA.8 The County's modeling, in contrast to the EPA's study, predicted that Gallagher's SO2 emissions alone would repeatedly violate the NAAQSs for SO2 in Jefferson County, even without the addition of background SO2 emissions. The County further contended that the three criteria announced in the proposed notice of denial did not adequately address the issues raised by the petition, and that the Administrator's use of the new criteria denied the County due process.

In response to Jefferson County's comments and modeling study, EPA conducted another modeling study using four of the five factors that the County had suggested.9 The EPA found that these changes made no significant difference in the modeling results. Using either its original figures, or four of the five factors proposed by Jefferson County, EPA calculated that only about three percent of the SO2 concentration at any location in Jefferson County where the NAAQSs are violated is attributable to Gallagher. However, an EPA modeling study also stated that:

The highest second-highest predicted impact on a 24-hour average in Kentucky from Gallagher is 126 ug/m3 [micrograms per cubic meter], which is about 34.5% of the primary NAAQS. This is a substantial portion of the NAAQS and has the potential to limit the increment available to new sources in Louisville. The highest second-highest predicted 3-hour concentration in Kentucky resulting from the plant is 608 ug/m³. This represents 47% of the secondary NAAQS, and has a far more serious potential for limiting growth in Kentucky.¹⁰

In fact, the EPA's study concluded that by 1985 Gallagher's emissions "will be the predominate [sic] influence upon air quality in Louisville, Kentucky."

Notwithstanding these determinations, the EPA, on February 16, 1982, finally denied Jefferson County's section 126 petition for interstate pollution abatement. 47 Fed.Reg. 6624. The EPA concluded that "the Gallagher plant does not cause or substantially contribute to a violation of the SO2 NAAQS." Id. at 6628.11 It is from this decision that the Air Pollution Control District of Jefferson County appeals.

III. Procedural Issues.

Under the Act, we may reverse the action of the Administrator for failure to observe the producers required by law if

1) the failure to observe the procedure(s) is arbitrary or capricious, and,

2) a specific objection to the procedure employed was raised during the public comment period (or afterward if the grounds for objection arose only after the comment period and the "objection is of central relevance to the outcome of the rule"), and,

3) if "the errors were so serious and related to matters of such central relevance to the rule that there is a substantial likelihood that the rule would have been significantly changed if such errors had not been made."

42 U.S.C. Sec. 7607(d)(9)(D) (paraphrased, except where indicated).

The District of Columbia Circuit has observed that "[t]he essential message of so rigorous a standard is that Congress was concerned that EPA's rulemaking not be casually overturned for procedural reasons." Sierra Club v. Costle, 657 F.2d 298, 391 (D.C.Cir.1981) (referring to 42 U.S.C. Sec. 7607(d)(9)(D)). Because the statute's conditions are stated conjunctively, a reviewing court may not reverse a decision of the EPA solely because the court determines that the Agency has not observed the procedures required by law. The EPA's failure to observe proper procedures must be arbitrary and capricious, and essentially, go to the heart of the decision-making process to justify reversal.

Jefferson County raises various procedural objections. The County contends that the EPA substantially prejudiced the County's rights by delaying the final decision on the section 126 petition far beyond the sixty days mandated by statute. The County's second objection is that the EPA, in making its determination, improperly considered information that was submitted after the close of the official comment period. Finally, the County challenges the EPA's issuance of three new criteria for evaluating section 126 petitions.

A. Delay by the EPA.

The Clean Air Act provides that any state may petition the Administrator for a finding that a major source in one state emits air pollutants in amounts that prevent another state from either achieving the NAAQSs or from preventing the significant deterioration of air quality. 42 U.S.C. Sec. 7426(b). The statute provides that the Administrator must hold a public hearing on the petition and that, within 60 days after the hearing, "the Administrator shall make such finding or deny the petition." Id.

Jefferson County filed its section 126 petition on May 14, 1979; a hearing was not held until April 17, 1980. After waiting 7 1/2 months for a decision, Jefferson County, on December 31, 1980, filed suit in district court to compel a decision. The district court entered an order on May 29, 1981 requiring the Administrator to render a decision on the petition "as expeditiously as possible and in no event later than sixty (60) days" from the order. On July 30, 1981, the Administrator published a proposed determination. Finally, on February 16, 1982, 22 months after the hearing, the EPA denied Jefferson County's petition.

Clearly the EPA failed to observe the time requirement of the Act. The County urges that the inordinate delay alone justifies granting the section 126 petition. However, such an approach would be inappropriate for two reasons.

Under 42 U.S.C. Sec. 7607(d)(9)(D), the Administrator's procedural errors constitute grounds for reversal only if the failure to observe procedure was "arbitrary and capricious," and the errors were so serious that there is a substantial likelihood that absent the errors, a significantly different result would have been reached. Here, although the delay was excessive in light of the statutory time limit, the County has not established that the delay was "arbitrary and capricious." There were legitimate reasons for the delay. The EPA conducted several modeling studies: one prior to the hearing, one subsequent to the hearing, and one subsequent to the proposed denial of the petition. The EPA received comments following each modeling study and solicited additional information from interested parties throughout this period. We are unable to hold that in the circumstances the delay was clearly arbitrary or capricious; it could well have resulted from EPA's desire to evaluate all comments and to run a sufficient number of modeling studies in response to the comments. Also, the record indicates that much of the delay was attributable to EPA's efforts to take the comments and computer modeling of Jefferson County into account in rendering a decision. Jefferson County simply has not met its burden of establishing a substantial likelihood that a significantly different result would have been reached by EPA absent the delay.

The second reason it is inappropriate to grant the section 126 petition in response to EPA's delay is that Jefferson County has already availed itself of the remedy provided under the Clean Air Act. 42 U.S.C. Sec. 7604(a)(2) provides that suits against the Administrator may be brought in federal district court if the Administrator fails to perform an act or duty that is not discretionary. Jefferson County availed itself of this remedy when it obtained a district court order compelling a decision by the Administrator. Although the County may be dissatisfied with this remedy, it appears to be the only relief contemplated under the statute. As the Second Circuit observed regarding the EPA's failure to respond to a section 126 petition before the Agency approved a proposed revision of New York's SIP, "[w]hile we cannot condone the EPA's disregard of this procedural mechanism established by Congress, the Agency's inaction provides no basis for overturning its decision ...." Connecticut v. EPA, 696 F.2d 147, 168 (2d Cir.1982). In fact, the Congressional Conference Committee that considered the 1977 amendments to the Act specifically rejected a Senate amendment which would have treated the Administrator's inaction on a section 126 petition after the 60-day time period as granting the petition. H.R.Rep. No. 564, 95th Cong., 1st Sess. 146 reprinted in 1977 U.S.Code Cong. & Ad.News 1502, 1526-27. Thus, Jefferson County's argument with respect to the delay by the Administrator is not well taken.

B. Information Submitted After the Record was Closed.

Jefferson County contends that the entire decision-making process was tainted, because the EPA accepted data from the Public Service Company of Indiana ("PSI"), after the close of one of the comment periods. This claim must also fail. Although EPA did receive data after the formal comment period, Jefferson County was neither prejudiced thereby nor was it denied an opportunity for meaningful review.

The Clean Air Act does not specify how section 126 proceedings are to be conducted. Consequently, we believe that the Administrator has considerable discretion in determining the extent to which ex parte comments may be considered in a section 126 proceeding. The Act does state that all comments and documents received during the comment period should promptly be placed in the docket; any documents "which become available after the proposed rule has been published and which the Administrator determines are of central relevance to the rulemaking shall be placed in the docket as soon as possible after their availability." 42 U.S.C. Sec. 7607(d)(4)(B)(i) (emphasis added). The D.C. Circuit has read this portion of the Clean Air Act as permitting the EPA to consider comments submitted after the close of the comment period. Sierra Club v. Costle, 657 F.2d 298, 397-98 (D.C.Cir.1981). This seems a reasonable interpretation of section 7607(d)(4)(B)(i), since this subparagraph refers both to comments submitted during the comment period and comments submitted afterward. However, while the Clean Air Act does not require the EPA to reject all information submitted to it outside of the formal comment period, we agree that there must be some check upon ex parte contact with the Agency to ensure that interested parties have an opportunity to comment on important information. The guideline used by the court in Sierra Club v. Costle to determine whether an impermissible ex parte contact had occurred was whether "documents vital to EPA's support for its rule were submitted so late as to preclude any effective public comment." Id. at 398.

While Jefferson County contends that it was prejudiced by EPA's consideration of post-comment documents submitted by PSI, the County had over one year in which to respond to the information submitted to EPA after the comment period. In fact, Jefferson County did respond to this data on August 28, 1981 in its critique of the EPA's proposed determination. Unlike Sierra Club v. Costle where there was no reopening of the formal comment period by EPA, here the Agency conducted two additional comment periods following the allegedly impermissible ex parte contact. 46 Fed.Reg. 15,743 (Mar. 9, 1981); 46 Fed.Reg. 38,937 (July 30, 1981). Jefferson County had ample opportunity to, and actually did, comment on the information accepted by the EPA. The decision-making process was therefore not tainted by the EPA's decision to accept data submitted after the close of the comment period.

C. Publication of Three New Criteria.

In its announcement of the public hearing on Jefferson County's section 126 petition, the EPA listed eight criteria12 as being among the issues "that should be addressed by the interested parties and the public." 45 Fed.Reg. 17,048, 17,049-50 (Mar. 17, 1980). However, in the proposed determination of July 30, 1981, the EPA did not refer to the eight criteria published earlier, but instead announced three new criteria13 "that the Administrator uses in making her determination" on section 126 petitions. 46 Fed.Reg. 38,937, 38,939. Although the proposed determination stated that Jefferson County's petition and submissions addressed each of the three new criteria, Jefferson County argues that it was denied due process because the EPA decision was not based on the eight criteria announced previously.

Jefferson County, relying upon Greene v. United States, 376 U.S. 149, 84 S.Ct. 615, 11 L.Ed.2d 576 (1964), asserts that it was denied due process because the introduction of the new criteria interfered with certain "antecedent rights" which apparently arose when the EPA published the eight original criteria. This argument lacks merit.

The facts here are readily distinguishable from Greene. The eight criteria published by the EPA did not have the force of a statute, as did the regulation in Greene. Further, the EPA made it clear that the eight criteria here were not exhaustive: "Issues that should be addressed by the interested parties and the public include the ... [eight criteria] given below." 45 Fed.Reg. 17,04 8, 17,049 (Mar. 17, 1980) (emphasis added). Finally, although the EPA published the three new criteria, it also stated that Jefferson County had addressed those criteria. Jefferson County was even invited to submit additional information if it so desired. Moreover, we believe that were we to hold that by suggesting guidelines for submitting information the EPA created irrevocable "antecedent rights," the Agency's ability to collect pertinent information regarding a section 126 petition would be seriously hampered.

The limited review authorized by section 7607(d)(9)(D) does not compel reversal here. The procedures employed by the EPA, while not ideal, generally ensured that all parties were given ample opportunity to submit information and to comment on the EPA's determinations. Jefferson County's real quarrel seems to lie with the EPA's substantive determinations.

IV. Substantive Issues.

In addition to the procedural standard of 42 U.S.C. Sec. 7607(d)(9)(D) discussed above, subsections 7607(d)(9)(A), (B), and (C) provide that the court of appeals may reverse any action of the Administrator which is found to be:

(A) arbitrary, capricious, an abuse of discretion, or otherwise not in accordance with law;(B) contrary to constitutional right, power, privilege, or immunity;

(C) in excess of statutory jurisdiction, authority, or limitations, or short of statutory right....

Jefferson County does not argue, pursuant to subsection (B), that the EPA acted unconstitutionally. It does, however, challenge the EPA's decision as arbitrary or capricious under subparagraph (A) and asserts that, contrary to subparagraph (C), the Administrator exceeded her statutory authority, jurisdiction, or limitations.

The "arbitrary or capricious" standard of review is a deferential one which presumes that an agency's actions are valid. E.g., Citizens to Preserve Overton Park, Inc. v. Volpe, 401 U.S. 402, 415, 91 S.Ct. 814, 823, 28 L.Ed.2d 136 (1971); Cincinnati Gas & Electric Co. v. EPA, 578 F.2d 660, 663 (6th Cir.1978), cert. denied, 439 U.S. 1114, 99 S.Ct. 1017, 59 L.Ed.2d 72 (1979). Regarding the EPA's decisions, we have observed that "we are required to affirm if there is a rational basis for the agency action and we are not 'empowered to substitute [our] judgment for that of the agency.' " Cleveland Electric Illuminating Co. v. EPA, 572 F.2d 1150, 1161 (6th Cir.) (citing Overton Park ), cert. denied, 439 U.S. 910, 99 S.Ct. 278, 58 L.Ed.2d 256 (1978); see also EPA v. National Crushed Stone Association, 449 U.S. 64, 83, 101 S.Ct. 295, 306, 66 L.Ed.2d 268 (1980) ("It is by now a commonplace that 'when faced with a problem of statutory construction, this Court shows great deference to the interpretation given the statute by the officers or agency charged with its administration.' ") (quoting Udall v. Tallman, 380 U.S. 1, 16, 85 S.Ct. 792, 801, 13 L.Ed.2d 616 (1965)). This view also comports with Train v. Natural Resources Defense Council, 421 U.S. 60, 95 S.Ct. 1470, 43 L.Ed.2d 731 (1975), where the Supreme Court noted that although the Agency's construction was not "the only one it permissibly could have adopted, we conclude that it was at the very least sufficiently reasonable that it should have been accepted by the reviewing courts." Id. at 75, 95 S.Ct. at 1480.

Thus, our role in reviewing the EPA's determinations is a limited one. If there is a rational basis for the EPA's determination, we must uphold it. Cleveland Electric Illuminating Co. v. EPA, 572 F.2d at 1161; see also National Steel Corp., Great Lakes Division v. Gorsuch, 700 F.2d 314, 321 (6th Cir.1983). At the same time, a reviewing court "does not serve as a mere rubber stamp for agency decisions." Lead Industries Association, Inc. v. EPA, 647 F.2d 1130, 1145 (D.C.Cir.), cert. denied, 449 U.S. 1042, 101 S.Ct. 621, 66 L.Ed.2d 503 (1980).

Jefferson County challenges the EPA's decision on four grounds. First, the County urges that the factors used by the EPA in its computer modeling studies were incorrect. Second, the County argues that the EPA's decision to deny the petition violates the Clean Air Act requirements of fairness and uniformity in the criteria, procedures and policies applied by regional officers and employees of the EPA. Third, Jefferson County contends that the EPA's decision to deny the section 126 petition violates the Clean Air Act because Gallagher has in effect been permitted to usurp Jefferson County's future margin for growth. Finally, the County argues that the EPA's use of the "substantial contribution" test to determine whether interstate pollution must be abated is improper.

A. The Factors Used in the EPA Modeling Studies.

Jefferson County disputes several of the factors used by the EPA in the revised modeling study: (a) the stack base elevation and stack height, (b) the 24-hour background concentration of SO2 , (c) the receptor grid spacing, (d) the choice of meteorological data, and (e) the stack exit gas velocity.

Upon the record provided, we conclude that the EPA had a rational basis for choosing each of the factors.

Jefferson County asserts that the stack base elevation and stack height used by the EPA (460 and 1010 feet, respectively, rather than 410 and 960 feet) are too high. We cannot very well go to the site, take measurements ourselves, and decide who is in fact right. The EPA's choice of the higher figures was based on a certified survey performed specifically for the Gallagher site. We accept the rationality of this choice.

Jefferson County also argues that the 24-hour background concentration of SO2 used in the EPA modeling is too low (17 ug/m³ rather than 37 ug/m³). However, EPA presents a rational basis for its use of the lower figure. According to the Agency, the lower background concentration is "consistent with regional background concentrations as recommended in EPA's monitoring guidelines." Further, the EPA identified 215 sources of SO2 in Jefferson County, individually modeled the significant producers of SO2 , such as the Louisville Gas and Electric power plants, and accounted for other area sources by calculating them