McEvoy v. IEI Barge Services, Inc.

In the

United States Court of Appeals
For the Seventh Circuit

Nos. 09-3494 & 09-3495

C HARLES M C E VOY,
Plaintiff-Appellant,
and

KKL D EVELOPMENT, LLC, et al.,
Plaintiffs-Appellants,
v.

IEI B ARGE S ERVICES, INC.,
Defendant-Appellee.

Appeals from the United States District Court
for the Northern District of Illinois, Western Division.
Nos. 06 C 50080 & 07 C 50007—Frederick J. Kapala, Judge.

A RGUED A PRIL 5, 2010—D ECIDED S EPTEMBER 7, 2010

Before E ASTERBROOK, Chief Judge, and B AUER and
W OOD , Circuit Judges.
W OOD , Circuit Judge. East Dubuque, Illinois, is a small
town on the Mississippi River. One local company that
has profited from the river’s proximity is IEI Barge Ser-
2 Nos. 09-3494 & 09-3495

vices, Inc. (“IEI”). IEI stores coal in an outdoor pile and
loads it onto river barges. As the coal is moved around,
coal dust is thrown off into the air. One of IEI’s neighbors,
Charles McEvoy, objected to the coal dust from IEI’s
operations, because it was drifting into his home; he
filed suit in federal court. McEvoy’s concerns were
shared by others in the area. KKL Development, LLC
(“KKL”), which owns commercial property in East
Dubuque, and Vroom Auto Mall and RV Plaza, Inc.
(“Vroom”), which runs its business on KKL’s property,
worried that the dust would accumulate on their inven-
tory and would create a hazard for their employees.
The companies filed their own lawsuit, which mirrored
McEvoy’s.
Law students and professors around the country
might find this story familiar; in a famous hypothetical,
pollution emanating from a nearby factory sullies recently
cleaned laundry drying on a clothesline. See, e.g., R OBERT
C OOTER & T HOMAS U LEN, L AW & E CONOMICS 100-04
(5th ed. 2007); Guido Calabresi & A. Douglas Melamed,
Property Rules, Liability Rules, and Inalienability: One View
of the Cathedral, 85 H ARV . L. R EV. 1089 (1972); Frank I.
Michelman, Pollution as a Tort: A Non-Accidental Perspec-
tive on Calabresi’s Costs, 80 Y ALE L.J. 647 (1971). The facts
offer a pedagogically useful vehicle for discussing how
different legal rules can be used to internalize external
costs. This appeal is not, however, about clean laundry
or the proper allocation of costs. Rather, it is about
which legal tools are available to someone who wants
to shift the cost of pollution to the polluter. We must
consider whether the Clean Air Act (the “Act”), 42 U.S.C.
Nos. 09-3494 & 09-3495 3

§§ 7401 et seq., supports a private right of action per-
mitting neighbors adversely affected by this coal dust to
enforce two Illinois environmental regulations that IEI
allegedly violated. The district court concluded that the
Act’s citizen-suit provision does not support such
an action. While we have no trouble recognizing why
plaintiffs are seeking a remedy, we too conclude that
the plaintiffs’ allegations fall outside the scope of the Act.

I
In the 1950s, Dubuque Sand & Gravel began opera-
tions in East Dubuque. In 1988, the company was
renamed IEI; it has conducted operations on the Missis-
sippi under that name ever since. IEI works with bulk
materials, including coal. The company receives the
materials from train cars, and either immediately loads
them onto river barges or stores them on its premises
in East Dubuque for later loading. According to the
plaintiffs, all of IEI’s activities release coal dust that is
blown by the wind onto adjacent properties.
As we have mentioned, each of the plaintiffs has a
stake in nearby property that is affected by the coal dust.
McEvoy owns residential property. He alleged that he
routinely observes coal dust crossing IEI’s property line;
he shuts his doors and windows to prevent the dust
from accumulating in his home. KKL owns commer-
cial property, which it leases to Vroom for use as a car
and RV-camper dealership. The companies alleged that
coal dust is regularly deposited on the dealership’s in-
4 Nos. 09-3494 & 09-3495

ventory. They also worried that constant exposure to
the coal dust would adversely affect employee health.
Fed up with this situation, the plaintiffs repaired to
federal court. McEvoy filed a complaint in April 2006, and
KKL and Vroom followed in January 2007. The com-
plaints alleged theories of recovery under the citizen-suit
provision of the Act. See 42 U.S.C. § 7604(a). (They also
raised claims under the Resource Conservation and Re-
covery Act (“RCRA”), 42 U.S.C. §§ 6901 et seq., and state-
law theories— namely, trespass, negligence, and nui-
sance.) As described in further detail below, the Act
provides for citizen suits to enforce certain limits set by
federal and state environmental laws. Invoking this
mechanism, the plaintiffs asserted that IEI was vio-
lating five Illinois environmental regulations. Two of
those regulations are at issue in this appeal. The first
is Section 201.141, entitled “Prohibition of Air Pollu-
tion,” which provides:
No person shall cause or threaten or allow the dis-
charge or emission of any contaminant into the en-
vironment in any State so as, either alone or in com-
bination with contaminants from other sources, to
cause or tend to cause air pollution in Illinois, or so as
to violate the provisions of this Chapter, or so as to
prevent the attainment or maintenance of any ap-
plicable ambient air quality standard.
ILL. A DMIN. C ODE , tit. 35, § 201.141. Second is Section
212.301, the “Fugitive Particulate Matter” regulation,
which states:
No person shall cause or allow the emission of fugitive
particulate matter from any process, including any
Nos. 09-3494 & 09-3495 5

material handling or storage activity, that is visible
by an observer looking generally toward the zenith
at a point beyond the property line of the source.
ILL. A DMIN. C ODE, tit. 35, § 212.301.
IEI responded with motions for summary judgment in
both cases; it asked the court to find that the plaintiffs
had failed to state a federal claim and then to dismiss the
supplemental state-law claims without prejudice. The
district court did just that on September 11, 2009,
granting IEI’s motions for summary judgment. Of particu-
lar relevance to this appeal, the district court concluded
that the Act did not provide a private right of action to
enforce the two Illinois regulations quoted above. (The
district court amended its judgment to comply with the
Federal Rules on May 7, 2010, but the substantive deci-
sions remained the same.)
The plaintiffs appeal only from the district court’s
judgment barring them from using the Act to enforce
Illinois’s Prohibition of Air Pollution and Fugitive Par-
ticular Matter regulations. They do not challenge the
district court’s disposition of the claims based on the
other Illinois regulations, nor have they complained about
its decisions on their RCRA and state-law claims. We
consolidated these appeals for our review.

II
The Act brings together federal, state, and private
resources for the purpose of protecting and enhancing
the quality of the nation’s air. 42 U.S.C. § 7401. Central
6 Nos. 09-3494 & 09-3495

among the tools that the Act creates to effectuate these
objectives are the national ambient air quality standards
(the “NAAQS”), see id. § 7409. The NAAQS are set by
the federal Environmental Protection Agency (the “EPA”)
and further implemented through State Implementa-
tion Plans (“SIPs”), see id. § 7410. (We apologize for this
mess of alphabet soup, but these abbreviations are in
such common use that it would only confuse to adopt
anything more felicitous.) SIPs are required if the state
wants additional emission limitations; they also estab-
lish the regime governing pollution permits. Id.
Setting standards is just the first step; without effective
enforcement those standards would be so many words
on a piece of paper. The Act authorizes the EPA to
enforce its provisions and implementing rules. 42 U.S.C.
§ 7413. In addition, the Act includes a “citizen suits”
provision, which provides that private citizens may
bring civil actions in federal courts against, among
others, violators of emission standards or limitations. Id.
§ 7604(a)(1)(A). Citizen-suit provisions in environmental
laws empower individual persons to serve as private
attorneys general and to enforce standards set at the
federal or state level. The theory is that the efforts of these
private parties will supplement governmental enforce-
ment.

A
As we have already noted, McEvoy and his fellow
plaintiffs have alleged that IEI violated Illinois’s Prohibi-
tion of Air Pollution and Fugitive Particulate Matter
Nos. 09-3494 & 09-3495 7

regulations. They identified the Act’s citizen-suit provi-
sion as the source of their entitlement to seek a remedy
for those alleged violations. This appeal asks us to look
closely at the types of provisions that a citizen may
enforce through the Act. The plaintiffs invoked the Act’s
express right of action “against any person . . . who is
alleged to have violated . . . or to be in violation of (A) an
emission standard or limitation under this chapter . . . .”
42 U.S.C. § 7604(a)(1)(A). One learns immediately from
this language that the right to sue is tethered to the
Act’s definition of the phrase “emission standard or
limitation under this chapter.” See id. § 7604(f). Paragraph
(f) creates four categories of enforceable standards and
limitations. The plaintiffs are relying on subparagraphs
(f)(1) and (f)(4), and so we reprint only those parts of the
definition here. Emission standards and limitations
enforceable through § 7604(a)(1)(A) include:
(1) a schedule or timetable of compliance, emis-
sion limitation, standard of performance or emis-
sion standard, [or]
...
(4) any other standard, limitation, or schedule
established under any permit issued pursuant to
[42 U.S.C. §§ 7661-7661f] or under any applicable
State implementation plan approved by the Ad-
ministrator, any permit term or condition, and
any requirement to obtain a permit as a condition
of operations[,]
which is in effect under this Act (including a
requirement applicable by reason of [42 U.S.C.
8 Nos. 09-3494 & 09-3495

§ 7418]) or under an applicable implementation
plan.
42 U.S.C. § 7604(f). To establish a right of action, there-
fore, the plaintiffs must identify a regulation that
qualifies as an “emission standard or limitation” as
defined in subparagraphs (1) and (4). We begin by ex-
amining what these subparagraphs tell us about the
types of emission standards or limitations that are en-
forceable under the Act, and then we consider whether
the particular Illinois regulations on which plaintiffs
rely meet those criteria.
A plaintiff may sue to enforce a regulation if that regula-
tion is “a schedule or timetable of compliance, emission
limitation, standard of performance or emission stan-
dard.” 42 U.S.C. § 7604(f)(1). We look to the definitions
section of the Act for the meaning of the key terms, in-
cluding “emission limitation,” “emission standard,”
“standard of performance,” and “schedule and timetable
of compliance.” Id. § 7602(k), (l) & (p).
The plaintiffs take the position that because § 7604(f) is
itself a definition, it “trumps” any other definitions pro-
vided in the statute, by which they seem to mean
that when it came to this subsection, Congress for
some mysterious reason wanted its more precise defini-
tions not to apply. Pressing on, the plaintiffs argue that
§ 7604(f)(1) is independent of § 7602. This does not
make sense. There is nothing in the citizen-suit provision
indicating that Congress intended it to be insulated
from the rest of the statute. In fact, Congress said the
opposite in the chapeau to the definitions section; that
Nos. 09-3494 & 09-3495 9

introductory sentence begins by instructing readers that
the definitions apply “[w]hen used in this chapter.” Id.
§ 7602. The citizen-suit provision is most certainly part of
“this chapter,” and there is no language in the statute
indicating that the definitions are not applicable across-the-
board.
The plaintiffs’ citations to First and Fifth Circuit deci-
sions do not rescue their position. They rely on a foot-
note from a First Circuit decision, Conservation Law Founda-
tion v. Federal Highway Administration, 24 F.3d 1465, 1477
n.5 (1st Cir. 1994) (suggesting the “trumping” theory),
but that court has since applied the definitions section to
§ 7604(f)(1), see Conservation Law Foundation v. Busey, 79
F.3d 1250, 1258 (1st Cir. 1996). The Fifth Circuit decision
addressed § 7604(f)(4). See CleanCOALition v. TXU
Power, 536 F.3d 469 (5th Cir. 2008). Subparagraph
(f)(4)—unlike (f)(1)—uses terms that are not defined in
§ 7602, and so there is nothing strange about a con-
clusion that § 7604(f)(4) to that extent stands on its own
legs, while at the same time realizing that terms defined
in § 7602 retain those definitions when they appear in
§ 7604(f)(1).
We therefore proceed on the understanding that plain-
tiffs are bound to the statutory definitions, wherever the
defined terms appear. Their argument on appeal can
thus be boiled down to the proposition that the Illinois
provisions constitute “emission standards” or “emission
limitations” under § 7602(k). They do not assert that IEI
has violated any “standards of performance” and “sched-
ules or timetables of compliance” under § 7602(l) and (p).
10 Nos. 09-3494 & 09-3495

Accordingly, in order to prevail, they must identify an
Illinois regulation that establishes:
a requirement . . . which limits the quantity, rate,
or concentration of emissions of air pollutants on
a continuous basis, including any requirement
relating to the operation or maintenance of a
source to assure continuous emission reduction,
and any design, equipment, work practice or
operational standard promulgated under this
chapter.
42 U.S.C. § 7602(k) (defining “emission limitation” and
“emission standard”).
In addition to this general definition of “emission
standard or limitation under this chapter,” there is a
catchall provision in the Act that allows citizens to sue
to enforce
any other standard, limitation, or schedule estab-
lished under any permit issued pursuant to [42
U.S.C. §§ 7661-7661f] or under any applicable
State implementation plan approved by the Ad-
ministrator, any permit term or condition, and
any requirement to obtain a permit as a condition
of operations . . . .
42 U.S.C. § 7604(f)(4). Plaintiffs seek to enforce both of
the Illinois regulations under this provision as well.

B
The question that perplexed the district court was
whether a plaintiff is authorized to enforce standards
Nos. 09-3494 & 09-3495 11

and limitations found only in an SIP through this provi-
sion. The key phrase for this purpose is “under any
applicable State implementation plan.” The district
court concluded that this text lends itself to two
reasonable interpretations. Under the first, the statute
authorizes citizen enforcement of “any other standard,
limitation, or schedule established . . . under any ap-
plicable State implementation plan,” while under the
narrower reading it would allow enforcement only of
“any other standard, limitation, or schedule established
under any permit issued . . . under any applicable State
implementation plan.” (Emphasis added.) Under the
former view, a plaintiff is entitled to enforce all par-
ticular standards spelled out in an SIP, while the
latter view contemplates private enforcement only of
standards, limitations, or schedules reiterated in a
permit issued under an SIP. The district court concluded
that the language of the statute was ambiguous, but
that other tools of statutory interpretation favored the
latter option. Since McEvoy and his fellow plaintiffs
were not seeking to enforce a permit term, the district
court concluded that their case had to be dismissed.
Contrary to the district court, we find that the
statute permits citizen enforcement of standards found
in an SIP, even if those standards are not repeated in a
permit. We begin with the language of the statute.
Unlike the district court, we do not find the statute to
be ambiguous. It can and should be read in the first way
that the district court identified. Looking again at the
language, we see that citizens may sue to enforce
standards “under any permit . . . or under any applicable
12 Nos. 09-3494 & 09-3495

State implementation plan . . . .” 42 U.S.C. § 7604(f)(4). That
does not suggest that permits are always necessary; to
the contrary, it indicates that the state plans are an alter-
nate legal basis for suit. The district court distinguished
between permits issued “pursuant” to the statute and
permits issued “under” an SIP. But that disregards the
fact that the Act—taking advantage of cooperative fed-
eralism—is enforced more generally through state
plans. At least in states that have an approved SIP, like
Illinois, there are no permits somehow issued directly
under the Act. The most natural grammatical reading
also has the advantage of avoiding this tension with
the overall statutory scheme.
Since the district court found the statute ambiguous,
it turned to legislative history, policy, and other deci-
sions for assistance. We see no need to delve into the
legislative history, but we will say a word about the
court’s other concerns.
First, the district court thought that the plaintiffs’
reading of subparagraph (f)(4), under which they would
be authorized to enforce any standard or limitation
found in an SIP, would render the more particularized
definition from § 7604(f)(1) redundant and superfluous.
If subparagraph (f)(4) applied to standards found in an
SIP that are not in a permit, it feared, then plaintiffs
would never need to show that a particular regulation in
an SIP met the definition in § 7602. To avoid this prob-
lem, the district court limited (f)(4) to suits about permits.
But the district court’s reading of (f)(1) and (f)(4) failed
to acknowledge the subtle differences between these
Nos. 09-3494 & 09-3495 13

two subparagraphs. Recall that (f)(1) defines the term
“emission standard or limitation under this chapter” as
“a schedule or timetable of compliance, emission limita-
tion, standard of performance or emission standard,”
and (f)(4) is a catchall that sweeps in “any other
standard, limitation, or schedule established [1] under
any permit issued pursuant to [the Act] or [2] under
any applicable State implementation plan . . . .” There
would have been no reason to include subpart (f)(4)
if Congress wanted enforcement only of permit terms;
that is the specific topic of § 7604(f)(3), and may also
overlap with (f)(1). We will not assume that Congress
had no purpose in mind for (f)(4). The fact that the dif-
ferent subparagraphs of § 7604(f) may overlap to a
degree is no reason to reject the natural reading of a
statute. Congress may choose a belt-and-suspenders
approach to promote its policy objectives, and it
appears that this is what it was doing when it
added the broader provision to the statute through a
later amendment. See Clean Air Act Amendments, Pub. L.
No. 101-549, § 707 (adding subparagraph (f)(4) to the
existing § 7604(f) in 1990).
The district court found it significant that § 7604(f)(4)
was adopted as part of the 1990 amendments to the Act,
but not for the sequencing reason we just mentioned.
Instead, the district court saw the 1990 amendments
as focused on permits and concluded that any am-
biguity in § 7604(f)(4) should be resolved in favor of an
interpretation that restricts citizen suits to the enforce-
ment of standards and limitations under permits. But,
as the plaintiffs rightly note, the 1990 amendments ex-
14 Nos. 09-3494 & 09-3495

panded the scope of the Act in a number of areas, only
some of which related to permits. For example, the 1990
amendments expanded the EPA’s civil enforcement
authority for SIPs without reference to permits. See Pub. L.
No. 101-549, § 701 (amending 42 U.S.C. § 7413).
Finally, the district court relied on a number of cases
to support its view. In our opinion, however, some of
those decisions are not on point, and others actually
support the plaintiffs. The district court cited five cases
in the main text of its memorandum to support its
reading of § 7604(f)(4), but four of those are not helpful, as
they address only the applicability of (f)(4) to permit
terms. See Romoland Sch. Dist. v. Inland Empire Energy Ctr.,
LLC, 548 F.3d 738 (9th Cir. 2008); Sierra Club v. Georgia
Power Co., 443 F.3d 1346 (11th Cir. 2006); United States
v. Northshore Mining Co., 2007 WL 4563418 (D. Minn.
2007); New York v. American Elec. Power Serv. Corp., 2006
WL 840390 (S.D. Ohio 2006). The fifth case, National
Parks Conservation Association v. Tennessee Valley Authority,
480 F.3d 410, 418 (6th Cir. 2007), quotes the relevant
statutory provision and inserts ellipses in the same
places as the district court did, but the question before
that court was whether the plaintiffs’ suit was timely, not
the substantive breadth of the citizen-suit provision. The
Sixth Circuit thus had no need to explore the issue that
is before us.
The district court acknowledged in an endnote that the
Fifth Circuit has adopted what it called a “broader
reading of the statute,” in CleanCOALition, supra. That is
true; moreover, that court addressed our question head
on and resolved it in the plaintiffs’ favor:
Nos. 09-3494 & 09-3495 15

It is true that § 7604(f)(4) was added as part of Title
V of [the Act’s] operating permit program . . . and
that certain clauses of that section are expressly
limited to operating permits. However, the first
clause is not so limited and broadly defines “emis-
sion standard and limitation” to include “any other
standard, limitation, or schedule established . . .
under any applicable State implementation plan.”
. . . Thus, the district court erred in concluding
that § 7604(f)(4), in its entirety, is limited to op-
erating permits.
536 F.3d at 476-77 (quoting 42 U.S.C. § 7604(f), and
citing Conservation Law Foundation, Inc. v. Romney, 421
F. Supp. 2d 344, 350 n.6 (D. Mass. 2006), and Communities
for a Better Environment v. Cenco Refining Co., 180 F. Supp.
2d 1062, 1082 (C.D. Cal. 2001), which reach the same
conclusion) (internal citations and footnote omitted). On
appeal, the plaintiffs have identified two other decisions
adopting their approach in dicta. See Ellis v. Gallatin
Steel Co., 390 F.3d 461, 475 (6th Cir. 2004); Save Our
Health Org. v. Recomp of Minnesota, 37 F.3d 1334, 1336
(8th Cir. 1994). The weight of authority thus favors
the approach plaintiffs have advocated.
We conclude that the natural reading of § 7604(f)(4) is
the best interpretation of that provision. Congress added
this paragraph to expand the scope of citizen suits to
include those based on standards, limitations, and sched-
ules under an SIP. This reading does not interfere
with citizen suits based on permit terms; so long as a
plaintiff has identified a standard, limitation, or schedule
16 Nos. 09-3494 & 09-3495

under any permit issued pursuant to 42 U.S.C. §§ 7661-
7661f, then that route is also available.

III
All of this may be enough to put the plaintiffs on the
path they desire, but it is not enough by itself. The final
and critical step is to decide whether the particular reg-
ulations that plaintiffs accuse IEI of violating set forth
judicially enforceable standards or limitations.
The first of the two provisions invoked by the plain-
tiffs illustrates well why one cannot take for granted
the suitability of judicial enforcement. Section 201.141 of
Illinois’s environmental regulations, entitled “Prohibition
of Air Pollution,” is little more than the commandment
“thou shall not pollute.” It states in relevant part that
“No person shall cause . . . or allow the discharge or
emission of any contaminant into the environment in
any State so as . . . to cause or tend to cause air pollution
in Illinois . . . .” ILL. A DMIN. C ODE, tit. 35, § 201.141. This
is not an “emission limitation” or “emission stan-
dard,”which § 7602(k) tells us must limit “the quantity,
rate, or concentration of emissions”—and so § 7604(f)(1)
does not apply. Indeed, we cannot see how this broad,
hortatory statement could be viewed as a “standard” or
“limitation” at all, and since it is not, then § 7604(f)(4) is
also unavailable. The Illinois environmental regulations
are chock full of specific rules; we do not think that this
statement of principle is the type of “standard” or “limita-
tion” for which Congress provided a cause of action in
§ 7604(a)(1)(A). (Plaintiffs proceed as if all “emissions”
Nos. 09-3494 & 09-3495 17

were also “pollution.” Perhaps that would make the
rule concrete, but it would also make it absurd. Pol-
lution is almost certainly a subset of emissions; otherwise,
every time a person exhales carbon dioxide or sneezes
she would be “polluting” the air. No one thinks that
Illinois has prohibited breathing. The emissions covered
by the Act must therefore be defined with some
greater specificity, so that people will know what is
forbidden.)
The “Fugitive Particular Matter” regulation, ILL. A DMIN.
C ODE, tit. 35, § 212.301, is a closer call. IEI argues that the
Fugitive Particular Matter regulation cannot qualify
through § 7604(f)(1) because it does not regulate “emissions
of air pollutants on a continuous basis” (emphasis added),
as the definition in § 7602(k) requires. Whether or not IEI
is right on this issue is of no importance, though, if plain-
tiffs can fall back on the broader language in § 7604(f)(4)
and avoid any requirement of continuity.
Once again, the central question is whether the
Fugitive Particulate Matter regulation is specific
enough for judicial enforcem ent. The Fugitive
Particulate Matter regulation is not like the highly
specific limitations and standards found elsewhere in
Illinois’s environmental regulations, see, e.g., ILL. A DMIN.
C ODE, tit. 35, §§ 212.123 (limiting certain visible
emissions to specified opacity percentages) and 214.121
(limiting certain sulfur-dioxide emissions based on
actual heat input), but it is not as grandly general as the
Prohibition of Air Pollution, supra. We must decide
where on the spectrum running from the specific and
18 Nos. 09-3494 & 09-3495

enforceable to the hortatory and unenforceable this reg-
ulation falls. This is a question of first impression in
federal or state court.
The regulation refers to fugitive particulate matter “that
is visible by an observer looking generally toward the
zenith at a point beyond the property line of the
source.” ILL. A DMIN . C ODE, tit. 35, § 212.301. The ques-
tions raised by these mere 19 words are manifold: What
are the characteristics of the observer? Where is she
standing? Must the matter be visible to the naked eye, and
if so, whose naked eye? Is “looking generally toward
the zenith” different from looking toward the zenith?
Do weather conditions matter? Are there a minimum
number of days per year, or hours per day, for assessing
visibility? We do not mean that these are metaphysical
questions that cannot be answered. Indeed, we have
identified some potential answers in Illinois law. See
Cassens Transp. Co. v. The Industrial Comm’n, 844 N.E.2d
414, 419 (Ill. 2006) (discussing relevant background rules
of statutory interpretation); Paulus v. Smith, 217 N.E.2d
527, 534 (Ill. App. Ct. 1966) (discussing the meaning of
“visible” in a municipal ordinance); see also ILL. A DMIN.
C ODE, tit. 35, § 201.122 (providing a background rule for
evaluating evidence of emissions, but not, by its terms, for
evaluating standards or limitations placed on emissions).
But the regulation does not tell us which of these
standards it has incorporated, nor does it suggest that
judges have any particular expertise that might be used
to craft a parallel system of regulation for this potentially
broad area.
Nos. 09-3494 & 09-3495 19

We are not the only ones to recognize that this kind of
regulation occupies a grey area. The history of this part
of Illinois’s environmental code reveals that the drafters
knew that visual emission standards are inherently prob-
lematic, yet they concluded that visual emission
standards can play a vital part in Illinois’s attempt to
protect its air quality:
Standards based upon the visual appearance of an
emission are long-standing, familiar, and relatively
unsophisticated. They were much assailed by
industry during our hearings, largely because of their
subjective nature. . . . On the other hand, pending
considerable improvements in scientific monitoring
practices, in many cases the appearance of an opaque
plume may be the best available evidence of
improper operation. With all its drawbacks, therefore,
the visual standard is an indispensable enforce-
ment tool.
In re Emissions Standards, Illinois Pollution Control Board,
Opinion of the Board, R71-23 (Apr. 13, 1972), at 4-310. We
do not, however, read this history as a directive that all
references to visual emissions necessarily create rules
that may be enforced by courts in private suits, rather
than standards that the public authorities might wish to
use. It is noteworthy that other visual emission limits in
the same part of the Code are better candidates for
judicial enforcement. See, e.g., ILL. A DMIN. C ODE, tit. 35,
§§ 212.122 (setting particulate-matter limits based on
opacity percentage), 212.123 (same), 212.304 (establishing
storage pile operational procedures where uncontrolled
20 Nos. 09-3494 & 09-3495

fugitive-particulate-matter emissions exceed a particular
mass per year); see also ILL. A DMIN. C ODE, tit. 35, § 212.107
(establishing a method for measuring visual emission,
and expressly providing that it does not apply to the
Fugitive Particulate Matter regulation). These regula-
tions include metrics that are susceptible to objective
evaluation in court. The Fugitive Particulate Matter
regulation does not.
Recognizing the ambiguity in the text of the regula-
tion, we asked the parties during oral argument if they
could identify any specific rules or background principles
in Illinois law to guide our interpretation. The parties
submitted supplemental briefs on this question, and we
thank them for their efforts. In the final analysis, however,
we were convinced by these submissions and our own
research that it is not our role to flesh out this regulation
without better guidance from the competent administra-
tive bodies. In addition, we do not exclude the possi-
bility that an Illinois court might be able to clarify some
of the ambiguity. Any statements from the Illinois execu-
tive branch—including, but not limited to, formal or
informal guidance from the Illinois Environmental Protec-
tion Agency—should be given due consideration by
any court interpreting this provision and its interaction
with the Act. Without any such guidance, however, we
conclude that the Fugitive Particulate Matter regulation
cannot be used as the basis of a citizen’s suit under
the Clean Air Act.
With the federal claims out of the case, the district court
was well within its rights to dismiss the supplemental
Nos. 09-3494 & 09-3495 21

state claims without prejudice. The judgments of the
district court are A FFIRMED.

9-7-10