In the
United States Court of Appeals
For the Seventh Circuit
No. 10-3891
S TATE OF M ICHIGAN, et al.,
Plaintiffs-Appellants,
and
G RAND T RAVERSE B AND OF O TTAWA
AND C HIPPEWA INDIANS,
Intervenor-Appellant,
v.
U NITED S TATES A RMY C ORPS OF E NGINEERS, et al.,
Defendants-Appellees,
and
C ITY OF C HICAGO, et al.,
Intervenors-Appellees.
Appeal from the United States District Court
for the Northern District of Illinois, Eastern Division.
No. 10 C 4457—Robert M. Dow, Jr., Judge.
A RGUED M AY 5, 2011—D ECIDED A UGUST 24, 2011
O PINION P UBLISHED S EPTEMBER 13, 2011
This opinion was originally released in typescript on
August 24, 2011.
2 No. 10-3891
Before M ANION, W OOD , and W ILLIAMS, Circuit Judges.
W OOD , Circuit Judge. Ambitious engineering projects
that began at the time that the City of Chicago was
founded have established a waterway in northeastern
Illinois that connects Lake Michigan to the Mississippi
watershed. (Additional links between the Mississippi
and the Great Lakes exist elsewhere, from northern
Minnesota to New York.) The system of canals, channels,
locks, and dams, with which we are concerned, known
today as the Chicago Area Waterway System (or CAWS,
as the parties call it in their briefs), winds from the
mouth of the Chicago River and four other points on
Lake Michigan to tributaries of the Mississippi River in
Illinois. The navigable link has been a boon to industry
and commerce, and it supports transportation and recre-
ation. Public health crises that once were common
because the Chicago River emptied the City’s sewage
into the lake—the City’s freshwater supply—vanished
thanks to the Chicago Sanitary and Ship Canal, which
reversed the flow of the Chicago River so that it now
pulls water from the lake, into the CAWS, and down
toward the Mississippi. During heavy rains and seasonal
high waters in the region, the CAWS is used to control
flooding.
This effort to connect the Great Lakes and Mississippi
watersheds has not been without controversy. At the
turn of the 20th century, Missouri sued in the Supreme
Court to stop Illinois from opening the Sanitary and Ship
Canal. An opinion by Justice Holmes rejected Missouri’s
challenge; the Court concluded that the state had not
No. 10-3891 3
presented enough evidence to establish that the flow of
sewage toward the Mississippi would create a public
nuisance. Missouri v. Illinois, 200 U.S. 496 (1906); see also
Missouri v. Illinois, 180 U.S. 208 (1901). Several years
later a broader fight erupted among the states bordering
the Great Lakes, and the Court began to issue decrees
setting the maximum rate at which Illinois may divert
water away from Lake Michigan and into the CAWS.
E.g., Wisconsin v. Illinois, 449 U.S. 48 (1980); Wisconsin v.
Illinois, 388 U.S. 426 (1967); Wisconsin v. Illinois, 311 U.S. 107
(1940); Wisconsin v. Illinois, 278 U.S. 367 (1929). Nor has
opening a pathway between these bodies of fresh water
come without costs. This appeal requires us to consider
one of those costs: the environmental and economic
harm posed by two invasive species of carp, commonly
known as Asian carp, which have migrated up the Missis-
sippi River and now are poised at the brink of this man-
made path to the Great Lakes. The carp are voracious
eaters that consume small organisms on which the
entire food chain relies; they crowd out native species
as they enter new environments; they reproduce at a
high rate; they travel quickly and adapt readily; and they
have a dangerous habit of jumping out of the water
and harming people and property.
In an attempt to stop the fish, Michigan, Minnesota,
Ohio, Pennsylvania, and Wisconsin, all states bordering
the Great Lakes, filed this lawsuit against the U.S. Army
Corps of Engineers (the Corps) and the Metropolitan
Water Reclamation District of Greater Chicago (the Dis-
trict), which together own and operate the facilities that
make up the CAWS. The plaintiff states allege that
4 No. 10-3891
the Corps and the District are managing the CAWS in a
manner that will allow invasive carp to move for the
first time into the Great Lakes. The states fear that if the
fish establish a sustainable population there, ecological
disaster and the collapse of billion-dollar industries that
depend on the existing ecosystem will follow. They say
that the defendants’ failure to close down parts of the
CAWS to avert the crisis creates a grave risk of harm, in
violation of the federal common law of public nuisance, see
American Electric Power Co., Inc. v. Connecticut, 131 S. Ct.
2527 (2011), and they advance a related claim against
the Corps based on the Administrative Procedure Act
(APA), 5 U.S.C. § 702. The states asked the district court
for declaratory and injunctive relief and moved for a
preliminary injunction that would require the defendants
to put in place additional physical barriers throughout
the CAWS, implement new procedures to stop invasive
carp, and expedite a study of how best to separate the
Mississippi and Great Lakes watersheds permanently.
Other parties intervened to protect their interests—the
Grand Traverse Band of Ottawa and Chippewa Indians
on the side of the plaintiffs, and the City of Chicago,
Wendella Sightseeing Company, and the Coalition to
Save Our Waterways as defendants. The district court
denied the motion for a preliminary injunction, and the
states appealed immediately. See 28 U.S.C. § 1292(a)(1).
We conclude that the court’s decision to deny prelimi-
nary relief was not an abuse of discretion. Our analysis,
however, differs in significant respects from that of the
district court, which was persuaded that the plaintiffs
had shown only a minimal chance of succeeding on
No. 10-3891 5
their claims. We are less sanguine about the prospects of
keeping the carp at bay. In our view, the plaintiffs pre-
sented enough evidence at this preliminary stage of the
case to establish a good or perhaps even a substantial
likelihood of harm—that is, a non-trivial chance that the
carp will invade Lake Michigan in numbers great enough
to constitute a public nuisance. If the invasion comes to
pass, there is little doubt that the harm to the plaintiff
states would be irreparable. That does not mean, how-
ever, that they are automatically entitled to injunctive
relief. The defendants, in collaboration with a great
number of agencies and experts from the state and
federal governments, have mounted a full-scale effort to
stop the carp from reaching the Great Lakes, and this
group has promised that additional steps will be taken
in the near future. This effort diminishes any role that
equitable relief would otherwise play. Although this
case does not involve the same kind of formal legal
regime that caused the Supreme Court to find displace-
ment of the courts’ common-law powers in American
Electric Power, on the present state of the record we have
something close to it. In light of the active regulatory
efforts that are ongoing, we conclude that an interim
injunction would only get in the way. We stress,
however, that if the agencies slip into somnolence or if
the record reveals new information at the permanent
injunction stage, this conclusion can be revisited.
I
To justify a preliminary injunction, the plaintiff states
must show that they are likely to succeed on the merits
6 No. 10-3891
of their claims, that they are likely to suffer irreparable
harm without an injunction, that the harm they would
suffer without the injunction is greater than the harm
that preliminary relief would inflict on the defendants,
and that the injunction is in the public interest. Winter v.
Natural Res. Def. Council, Inc., 555 U.S. 7, 20 (2008). We
will affirm the decision to deny a preliminary injunction
unless the district court has abused its discretion. Judge
v. Quinn, 612 F.3d 537, 557 (7th Cir. 2010). As usual, we
review questions of fact for clear error and questions of
law de novo. Girl Scouts of Manitou Council, Inc. v. Girl
Scouts of United States of Am., Inc., 549 F.3d 1079, 1086-87
(7th Cir. 2008).
II
We begin with the states’ likelihood of succeeding on
their common law public nuisance claim. The district
court thought that the states had “at best, a very modest
likelihood of success.” For the reasons discussed below,
we think that the district court underestimated the
likely merit of the states’ claim, particularly at this
early stage of the case.
A
The Supreme Court recently reminded us that when
it said, “There is no federal general common law,” in Erie
Railroad Co. v. Tompkins, 304 U.S. 64, 78 (1938), it did not
close the door on federal common law entirely. American
Electric Power, 131 S. Ct. at 2535-37. Instead, following
No. 10-3891 7
Erie, a “keener understanding” of federal common law
developed, under which federal courts “fill in ‘statutory
interstices,’ and, if necessary, even ‘fashion federal law’ ”
in areas “ ‘within national legislative power.’ ” Id. at 2535
(quoting Henry J. Friendly, In Praise of Erie—And of the
New Federal Common Law, 39 N.Y.U. L. Rev. 383 (1964)).
In American Electric Power, the Court reaffirmed a long
line of cases that have “approved federal common law
suits brought by one State to abate pollution emanating
from another State.” 131 S. Ct. at 2535-36. These
decisions reach at least as far back as the battle between
Missouri and Illinois over sewage, see Missouri v. Illinois,
supra, and they have continued from there, see Georgia
v. Tennessee Copper Co., 206 U.S. 230 (1907), New York v.
New Jersey, 256 U.S. 296 (1921), New Jersey v. City of
New York, 283 U.S. 473 (1931), Illinois v. City of Milwaukee,
406 U.S. 91 (1972) (Milwaukee I), City of Milwaukee v.
Illinois, 451 U.S. 304 (1981) (Milwaukee II), and American
Electric Power, 131 S. Ct. 2527. But it has been recognized
for a much longer period that the equitable power of
the courts extends to suits to abate public nuisances. See
United Steelworkers of America v. United States, 361 U.S. 39,
60-61 (1959) (Frankfurter, J., concurring) (assembling
examples from 16th century England to the turn of the
20th century in the United States).
It is our federal system that creates the need for a
federal common law to govern interstate disputes over
nuisances. Tennessee Copper explains that when the
states joined the union and in so doing abandoned their
right to abate foreign nuisances by force, “they did not
thereby agree to submit to whatever might be done.
8 No. 10-3891
They did not renounce the possibility of making rea-
sonable demands on the ground of their still remaining
quasi-sovereign interests; and the alternative to force is
a suit in this court.” 206 U.S. at 237. A state that wants
to bring a lawsuit attacking a nuisance emanating
from outside of its borders faces at least two legal dif-
ficulties: whom to sue, and what law to apply? If the
offender is another state, then the Constitution permits
an original action in the Supreme Court. U.S. C ONST.
art. III sec. 2, cl. 5. Whatever the venue, applicable law
is a problem: the offending state owes no allegiance to
the law of the plaintiff state, but the plaintiff state may
rightly fear protectionism if the law of the offending
state is used. Committee for Consideration of Jones Falls
Sewage Sys. v. Train, 539 F.2d 1006, 1008 (4th Cir. 1976)
(en banc). Responding to this concern, the Court has
concluded that in the context of interstate nuisances
“where there is an overriding federal interest in the
need for a uniform rule of decision or where the contro-
versy touches basic interests of federalism,” federal
common law governs. Milwaukee I, 406 U.S. at 105 n.6.
When evaluating claims based on the federal common
law of nuisance, courts must be mindful that they do
not have “creative power akin to that vested in Con-
gress.” American Electric Power, 131 S. Ct. at 2536.
1
The states’ public nuisance action here is based on
allegations that non-native species of carp (specifically,
bighead and silver carp) will migrate through water-
No. 10-3891 9
works operated by the defendants from rivers connected
to the Mississippi into Lake Michigan and on to the
other Great Lakes. “When we deal with air and water
in their ambient and interstate aspects, there is a federal
common law.” Milwaukee I, 406 U.S. at 103. We know
that this body of law applies in a dispute about “the
pollution of a body of water such as Lake Michigan
bounded, as it is, by four States,” id. at 105 n.6. But the
Court has cautioned that it has never “held that a
State may sue to abate any and all manner of pollution
originating outside its borders.” American Electric Power,
131 S. Ct. at 2536. The Corps and the District contend
that the common law does not extend to the allegations
in this case. They stress that they are not emitting “tradi-
tional pollutants”; all they have done, they say, is to
operate facilities in the CAWS through which invasive
species already living in local rivers might travel on
their own. We can dismiss the latter part of this argu-
ment without much discussion: the defendants bear
responsibility for nuisances caused by their operation of
a manmade waterway between the Great Lakes and
Mississippi watersheds. That they are not themselves
physically moving fish from one body of water to the
other does not mean that their normal operation of the
CAWS cannot cause a nuisance. See, e.g., R ESTATEMENT
(SECOND) T ORTS § 834 (“One is subject to liability for a
nuisance caused by an activity, not only when he carries
on the activity but also when he participates to a sub-
stantial extent in carrying it on.”) & cmt. (b) (defining
“activity” to include acts “that create physical condi-
tions that are harmful to neighboring land after the
activity that created them has ceased”).
10 No. 10-3891
Similarly, we know of no rule saying that the de-
fendants must emit a “traditional pollutant” in order for
federal common law to apply. While it may be true that
the introduction of an invasive species of fish into a
new ecosystem does not fit the concept of nuisance as
neatly as a spill of toxic chemicals into a stream, we do
not think the Supreme Court has limited the concept of
public nuisance as much as the defendants suggest. A
public nuisance is defined as a substantial and unreason-
able interference with a right common to the general
public, usually affecting the public health, safety, peace,
comfort, or convenience. R ESTATEMENT (SECOND) T ORTS
§ 821B; D AN B. D OBBS, T HE L AW OF T ORTS § 467, at 1334
(2000). It would be arbitrary to conclude that this type
of action extends to the harm caused by industrial pol-
lution but not to the environmental and economic de-
struction caused by the introduction of an invasive, non-
native organism into a new ecosystem (assuming that
the states have correctly forecast the depletion of the
Great Lakes fishery and the corresponding damage to
the multi-billion-dollar sports fishing industry). Public
nuisance traditionally has been understood to cover
a tremendous range of subjects:
It includes interferences with the public health, as
in the case of a hogpen, the keeping of diseased ani-
mals, or a malarial pond; with the public safety, as in
the case of the storage of explosives, the shooting of
fireworks in the streets, harboring a vicious dog, or
the practice of medicine by one not qualified; with
public morals, as in the case of houses of prostitution,
illegal liquor establishments, gambling houses, inde-
No. 10-3891 11
cent exhibitions, bullfights, unlicensed prize fights, or
public profanity; with the public peace, as by loud
and disturbing noises, or an opera performance
which threatens to cause a riot; with the public com-
fort, as in the case of bad odors, smoke, dust and
vibration; with public convenience, as by obstructing
a highway or a navigable stream, or creating a con-
dition which makes travel unsafe or highly disagree-
able, or the collection of an inconvenient crowd; and
in addition, such unclassified offenses as eavesdrop-
ping on a jury, or being a common scold.
K EETON, et al., P ROSSER AND K EETON ON T ORTS § 90, at 643-
45 (5th ed. 1984) (citations omitted). The Supreme Court’s
application of public nuisance principles to cases
involving shared water resources reflects this broad
understanding. For example, the Court has held that a
change in one state’s water-drainage system that causes
flooding on another state’s farms may create a public
nuisance, see North Dakota v. Minnesota, 263 U.S. 365, 374
(1923); just as the industrial contamination of a body
of water might, Arizona Copper Co. v. Gillespie, 230 U.S.
46, 57 (1913). In this vein, American Electric Power em-
phasized “that public nuisance law, like common law
generally, adapts to changing scientific and factual cir-
cumstances.” 131 S. Ct. at 2536. The types of invasive
carp that are the concern in this case have been
designated as injurious species by the U.S. Fish and
Wildlife Service, see 50 C.F.R. § 16.13(a)(2)(v); this designa-
tion means that it is a federal crime under the Lacy Act
to transport them around or into the United States, 16
U.S.C. §§ 3371-78. We conclude that the federal common
12 No. 10-3891
law of public nuisance extends to the problem that
the plaintiff states have identified.
2
The next question, which is raised only by the Corps,
is whether the plaintiff states may state a claim based on
the federal common law of public nuisance against the
United States. The Corps asserts that “the States have
shown no basis for recognizing a federal common-law
public nuisance claim against a federal agency.” But the
Corps has not developed the argument much beyond
this broad statement. Its brief moves instead to a discus-
sion of whether federal common law has been displaced
by congressional legislation and whether there is any
role for the courts to play when agencies have taken
concerted action to address a problem. These are two
important issues that we will explore below, but neither
point explains why a claim based on the federal common
law of public nuisance cannot move forward against
the United States. The plaintiff states have done little
to counter the Corps’s suggestion. They reply (unrespon-
sively, in our view) that “the federal common law of
public nuisance undoubtedly exists.”
The implications of finding that the United States
has created a public nuisance strike us as potentially
important and complex; this is not a topic that can be
thrown on the table and then ignored. In this connec-
tion, it is telling that the Supreme Court went out of its
way in American Electric Power to point out that it “ha[d]
not yet decided whether private citizens . . . or political
No. 10-3891 13
subdivisions . . . of a State may invoke the federal
common law of nuisance to abate out-of-state pollution.”
131 S. Ct. at 2536. It declined to answer that question
because it thought it best to resolve the case on other
grounds. But the Court’s statement cautions us to tread
carefully whenever we consider how far to push a
theory of federal common law. This concern is less
pressing for claims the Court has already recognized,
such as those against state or local governmental entities
or private parties. See, e.g., Missouri v. Illinois, 200 U.S.
496 (states), Milwaukee I, 406 U.S. 91 (political subdivi-
sions); Tennessee Copper, 206 U.S. 230 (private citizens).
We have not discovered any case in which the
Supreme Court has expressly authorized a public
nuisance action against the United States in its sovereign
capacity. A recent concurring opinion in the D.C. Circuit
makes the same observation, noting that “the Court has
not endorsed any federal common-law causes of action
against the Government during the post-Erie period.”
El-Shifa Pharm. Indus. Co. v. United States, 607 F.3d 836,
853 (D.C. Cir. 2010) (Kavanaugh, J., concurring). To under-
stand common-law public nuisance in a way that
would exclude suits against the United States would be
faithful to the ancient origins of nuisance, where the
term described the criminal act of infringing on the
rights of the Crown, see William L. Prosser, Private Action
for Public Nuisance, 52 Va. L. Rev. 997, 998 (1966); at
least during that era, no one would have contemplated
that the King or Queen could be the source of a nui-
sance. Whether this sort of sovereign prerogative has any
place in modern American law, as a concept distinct
14 No. 10-3891
from the sovereign immunity of the United States, is
a separate question. Perhaps there is also a modern justifi-
cation for the position that the federal common law of
public nuisance cannot operate against the government:
this area of federal common law exists to provide a uni-
form rule for interstate disputes that will serve the
national interest, and it may be thought illogical to say
that a federal actor, which in theory embodies the
national interest, is at the same time violating a judge-
made concept of that same interest.
On the other hand, there are respectable arguments
in favor of applying public nuisance to the acts of
federal agencies, depending on the activity in which the
agency is engaged. We have moved far beyond the
Divine Right of Kings and the concept that the Crown
can do no wrong. We may assume that an agency’s effort
to regulate private actors in a particular area would not
give rise to a claim of public nuisance. But it is hard
to see why the United States’s ownership of a dam,
power plant, or other facility should automatically fore-
close a public nuisance claim brought by a state for
harms created by the operation of that facility. If the
facility were located in and owned by State A and it was
damaging State B, then State B would be entitled to
assert a common-law claim against State A (or one of
its subdivisions or private citizens). Our case offers a
good illustration of the point: the Corps and the
District together operate facilities that are allegedly on
the verge of creating a nuisance in waters of the plaintiff
states; why should the plaintiffs be able to state a claim
against the District but not the Corps?
No. 10-3891 15
The possible inconsistencies that would be created by
such a rule may be the reason that no court has ex-
pressed concern about the appearance of the Tennessee
Valley Authority—a federally owned entity that was
created by Congress and acts like a private corporation—as
a defendant in a public nuisance lawsuit. See American
Electric Power, 131 S. Ct. 2527; North Carolina ex rel. Cooper
v. TVA, 615 F.3d 291 (4th Cir. 2010); North Carolina
ex rel. Cooper v. TVA, 515 F.3d 344 (4th Cir. 2008). In fact,
out of all public nuisance decisions we have identified
from either the Supreme Court or the Courts of Appeals
that involve a federal agency as a defendant, none
contains a whisper of discussion about whether the
claim runs against the United States. In addition to the
cases just mentioned, see Middlesex Cnty. Sewerage Auth. v.
National Sea Clammers Ass’n, 453 U.S. 1, 4 & n.3 (1981)
(claims against the Environmental Protection Agency
(EPA) and the Corps); Committee for Consideration of Jones
Falls Sewage Sys., 539 F.2d 1006 (claims against the
EPA); Massachusetts v. U.S. Veterans Admin., 541 F.2d
119 (1st Cir. 1976) (claims against the Veterans Admin-
istration). Whether the plaintiffs’ common-law action
can proceed against the Corps is a question that may
well require attention as this case proceeds. Given the
parties’ cursory exposition of the issue and our ultimate
conclusion that preliminary relief is not warranted, we
find it unnecessary to say more at this point. (We see
this as a question relating to the plaintiffs’ ability to
state a claim; it does not implicate the court’s jurisdic-
tion, and so there is nothing to prevent our declining to
reach it.) For now, we will assume that the states’ federal
16 No. 10-3891
common-law claim may proceed against all of the de-
fendants.
B
The defendants argue that two additional obstacles
also diminish the states’ likelihood of succeeding on
their public nuisance claim. The first concerns the sover-
eign immunity of the United States. The Corps contends
that even if it makes sense to apply public nuisance
principles against the United States, the Corps is never-
theless not subject to suit because the United States has
not waived its sovereign immunity for this kind of
claim. The second argument, which we address below,
is that congressional regulation of the invasive carp
problem has displaced any role for federal common law.
“Absent a waiver, sovereign immunity shields the
Federal Government and its agencies from suit.” F.D.I.C.
v. Meyer, 510 U.S. 471, 475 (1994). The Corps takes the
position that there is no such waiver of immunity for
lawsuits against the United States that seek declaratory
and injunctive relief based on a federal common-law
tort. Whether this is correct depends on the interaction
between section 702 of the APA and the Federal Tort
Claims Act (FTCA), 28 U.S.C. § 1346(b).
We begin with a look at the APA. Section 702 reads
as follows:
A person suffering legal wrong because of agency
action, or adversely affected or aggrieved by agency
action within the meaning of a relevant statute, is
No. 10-3891 17
entitled to judicial review thereof. An action in a
court of the United States seeking relief other than
money damages and stating a claim that an agency
or an officer or employee thereof acted or failed
to act in an official capacity or under color of legal
authority shall not be dismissed nor relief therein be
denied on the ground that it is against the United
States or that the United States is an indispensable
party.
5 U.S.C. § 702. “The first and second sentences of § 702
play quite different roles.” Veterans for Common Sense v.
Shinseki, 644 F.3d 845, 866 (9th Cir. 2011). The first
supplies a right to seek review of agency action; the
second, added by the 1976 amendments to the statute,
provides a waiver of sovereign immunity. Id. The
waiver covers actions that seek specific relief other than
money damages; this aptly describes the plaintiffs’ claim
for declaratory and injunctive relief. See Blagojevich v.
Gates, 519 F.3d 370, 371-72 (7th Cir. 2008) (noting that
§ 702 “waived sovereign immunity for most forms of
prospective relief”); see also Bowen v. Massachusetts, 487
U.S. 879, 893 (1988) (construing § 702’s waiver broadly
and remarking that “complaints [for] declaratory and
injunctive relief . . . [are] certainly not actions for money
damages”); Veterans for Common Sense, 644 F.3d at 864-65.
Moreover, the waiver in § 702 is not limited to claims
brought pursuant to the review provisions contained in
the APA itself. The waiver applies when any federal
statute authorizes review of agency action, as well as in
cases involving constitutional challenges and other
claims arising under federal law. Blagojevich, 519 F.3d at
18 No. 10-3891
372; Czerkies v. U.S. Dep’t of Labor, 73 F.3d 1435, 1437-38
(7th Cir. 1996) (en banc); see also Veterans for Common
Sense, 644 F.3d at 867-68; Trudeau v. Federal Trade
Comm’n, 456 F.3d 178, 186-87 (D.C. Cir. 2006); United
States v. City of Detroit, 329 F.3d 515, 520-21 (6th Cir. 2003)
(en banc); Jaffee v. United States, 592 F.2d 712, 718 (3d
Cir. 1979).
Although the United States has argued from time to
time that the “final agency action” requirement of § 704
limits the waiver of immunity in § 702, it has not prevailed
on that ground. E.g., Veterans for Common Sense, 644 F.3d at
866-68; Trudeau, 456 F.3d at 186-87. The Corps wisely does
not take that position here; as the Ninth Circuit explained
recently, the conditions of § 704 affect the right of action
contained in the first sentence of § 702, but they do not
limit the waiver of immunity in § 702’s second sentence.
Veterans for Common Sense, 644 F.3d at 866-68. The only
limitation on § 702 that requires our attention is the
clause that says, “Nothing herein . . . confers authority
to grant relief if any other statute that grants consent
to suit expressly or impliedly forbids the relief which is
sought,” 5 U.S.C. § 702(2), which Congress added to
the statute at the same time that it introduced the
waiver of sovereign immunity, see Pub. L. 94-574, 90 Stat.
2721 (Oct. 21, 1976). Pointing to this provision, the
Corps frames an argument by negative implication: it
says that when Congress enacted the FTCA in 1946, it did
so against a backdrop of no tort liability for the United
States; the FTCA waives the government’s sovereign
immunity in suits for money damages to the extent that
a private person would be held liable under applicable
No. 10-3891 19
state tort law, see 28 U.S.C. § 1346(b)(1); Smith v. United
States, 507 U.S. 197, 201-02 (1993); Parrott v. United States,
536 F.3d 629, 635 (7th Cir. 2008); but while the FTCA
authorizes actions for damages, it says nothing at all
about injunctive relief; thus, the FTCA implicitly
prohibits injunctive relief in tort suits against the United
States; and because of § 702(2), the Corps’s argument
concludes, the plaintiffs cannot use the APA’s waiver of
immunity to assert a common-law tort claim against
the United States.
That argument reads too much into congressional
silence. The FTCA authorizes various tort claims for
damages against the government to the extent that state
law would provide relief, and it spells out a number of
explicit exceptions. E.g., 28 U.S.C. § 2674 (barring puni-
tive damages and interest before judgment); id. § 2680
(limiting the waiver, among other circumstances, where
the alleged tort concerns the government’s enforcement
of a statute or a discretionary function). There is nothing
in the statute suggesting that Congress meant to forbid
all actions that were not expressly authorized. To the
contrary, section 702(2) requires evidence, in the form
of either express language or fair implication, that Con-
gress meant to forbid the relief that is sought. The
Corps’s effort to transform silence into implicit prohibi-
tion would seriously undermine Congress’s effort in
the APA to authorize specific relief against the United
States. When Congress amended the APA in 1976 it
gave every indication that it intended to provide specific
relief for all nonstatutory claims against the govern-
ment. See Trudeau, 456 F.3d at 186-87 (noting that all the
20 No. 10-3891
reports from Congress “identified as the measure’s
clear purpose elimination of the sovereign immunity
defense in all equitable actions” and that “the Senate
Report plainly indicated that Congress expected the
waiver to apply to nonstatutory actions”) (internal quota-
tion marks and alterations removed); Jaffee, 592 F.2d
at 718-19 (outlining the reasons for the amendments to
§ 702, the concern that some executive departments
were hiding behind their immunity, and concluding,
“It was therefore precisely for equitable actions under
section 1331 that Congress enacted the amendments
to section 702”).
The D.C. Circuit has read the Tucker Act, which it
interprets as the exclusive remedy for contract claims
against the government, to include an implicit prohibi-
tion against specific relief in contract actions against the
United States and thus to prevent reliance on the APA’s
waiver of immunity in such cases. Sharp v. Weinberger,
798 F.2d 1521, 1523-24 (D.C. Cir. 1986) (Scalia, J.). But the
same court has since decided that, whatever the
unspoken effect of the Tucker Act may be, the FTCA
does not contain a comparable implicit ban against
specific relief in tort cases against the government, and
thus that plaintiffs in such cases may take advantage of
the waiver in § 702 of the APA. U.S. Info. Agency v. Krc,
989 F.2d 1211, 1216 (D.C. Cir. 1993). To the same effect,
we recently explained that while “[t]he tort claims act
doesn’t authorize equitable relief . . . . [T]he Administra-
tive Procedure Act does,” and we went on to say that
a plaintiff asserting a tort claim against a federal
agency could take advantage of the APA to obtain equita-
No. 10-3891 21
ble relief. Robinson v. Sherrod, 631 F.3d 839, 841 (7th
Cir. 2011).
If that were not reason enough to reject the Corps’s
immunity defense, there is more. By its terms, the FTCA
does not apply to any federal common-law tort claim,
no matter what relief is sought. As the Corps itself
points out, state tort law—not federal law—is the source
of substantive liability under the FTCA. See Meyer, 510
U.S. at 478-79; Sobitan v. Glud, 589 F.3d 379, 388-89 (7th Cir.
2009); cf. Smith, 507 U.S. at 198 (no FTCA claim for tort
committed in Antarctica, a sovereignless entity not
subject to either state law or the law of a foreign country).
The states’ tort claim is based entirely on federal common
law, and so the claim would not be cognizable under
the FTCA in the first place. Meyer, 510 U.S. at 478. And
if the FTCA could never apply to the type of claim ad-
vanced, then there is no reason to think that it implicitly
forbids a particular type of relief for a claim outside its
scope. For all these reasons, we conclude that the waiver
contained in § 702 of the APA subjects the Corps to the
plaintiffs’ common-law claims for declaratory and in-
junctive relief.
C
The Corps and the District next contend that congres-
sional regulation has displaced as a matter of law the
federal common law on which the states rely. The
district court rejected this argument on the ground that
Congress had not done enough about the threat of
invasive carp to qualify for displacement of the federal
22 No. 10-3891
common-law claim. The defendants say this was error.
As they see things, it is enough that Congress has passed
legislation to stop the carp and that federal and state
agencies are hard at work to address the problem.
Because the parties disagree about the effect of American
Electric Power and the way in which the displacement
analysis should proceed, we begin with a few important
principles.
The doctrine of displacement rests on the premise
that federal common law is subject to the paramount
authority of Congress. New Jersey v. New York, 283 U.S. 336,
348 (1931); see also American Electric Power, 131 S. Ct. at
2537 (“[I]t is primarily the office of Congress, not
the federal courts, to prescribe national policy in areas of
special federal interest.”). “ ‘[W]hen Congress addresses
a question previously governed by a decision rested on
federal common law . . . the need for such an unusual
exercise of law-making by federal courts disappears.’ ”
American Electric Power, 131 S. Ct. at 2537 (quoting Mil-
waukee II, 451 U.S. at 314). Displacement focuses on
the relation between Congress and the federal courts—
it is not a doctrine that is concerned with the relation
between the federal courts and the executive branch.
This is a distinction often neglected by courts, as well as
by the parties to this case. Whether federal courts can
or should play a role in the face of comprehensive
agency action is a critical issue, which we address
below, but executive action or lack thereof does not
affect the displacement analysis. See American Electric
Power, 131 S. Ct. 2538-39 (rejecting the argument that an
agency must have taken action before common law is
No. 10-3891 23
displaced and explaining that the EPA’s outright refusal
to regulate emissions would not create a role for
federal common law because “the delegation [of reg-
ulatory authority from Congress to the agency] is
what displaces federal law”); Milwaukee II, 451 U.S. at
317-18, 324 n.18 (concluding that displacement had oc-
curred because “Congress . . . has occupied the field
through the establishment of a comprehensive reg-
ulatory program supervised by an expert administrative
agency,” regardless of how thoroughly the agency has
implemented that program) (emphasis added). Congress’s
decision to assign a particular problem to an executive
agency or its description of an agency’s role in addressing
a problem may be evidence of displacement, but the
ebb and flow of agency action neither diminishes nor
increases the role of federal common law. The important
displacement question is whether Congress has pro-
vided a sufficient legislative solution to the particular
interstate nuisance here to warrant a conclusion that
this legislation has occupied the field to the exclusion
of federal common law.
We readily concede that Congress has not been mute
on the subject of the carp, but that simply underscores
the critical question: how much congressional action is
enough? In their supplemental memoranda filed after
American Electric Power was decided, the defendants
seize upon the statement from the opinion that we
quoted above—that “the delegation is what displaces
federal law.” 131 S. Ct. at 2538. Their view is that
all Congress must do to displace federal law is to
indicate its intention to delegate a particular problem to
24 No. 10-3891
an executive agency. They read American Electric Power
as an enlargement of whatever displacement doctrine
existed previously. But the defendants have taken the
Court’s statement out of context. The Court in that
passage was responding to an argument that an agency
must have acted pursuant to its statutory power before
federal common law is displaced. See id. at 2538-39. The
Court explained that this was not the case and that it
is congressional action, not executive action, that guides
the displacement analysis. In so ruling the Court did not
establish a new test based solely on Congress’s delega-
tion of regulatory power; it simply pointed out that
delegation is one type of congressional action that is
evidence of displacement. “The test for whether con-
gressional legislation excludes the declaration of federal
common law,” the Court said, “is simply whether the
statute ‘speak[s] directly to [the] question’ at issue.” Id.
at 2537 (quoting Mobil Oil Corp. v. Higginbotham, 436 U.S.
618, 625 (1978), and citing Milwaukee II, 451 U.S. at 315,
and County of Oneida v. Oneida Indian Nation of N.Y., 470
U.S. 226, 236-37 (1985)). Importantly, while Congress
must have spoken to the particular question at issue, it
is not necessary for us to find the same manifest congres-
sional purpose that we would require in an analysis
of whether Congress has preempted state law. Id. at 2537.
Earlier federal nuisance cases provide additional
insight into the level of congressional action that is suffi-
cient to displace federal common law. In Milwaukee I,
where Illinois sued Milwaukee and other cities to stop
them from dumping sewage into Lake Michigan, the
Court decided that the federal common law of public
No. 10-3891 25
nuisance had not been displaced, despite the fact that
Congress had by that time “enacted numerous laws
touching interstate waters.” 406 U.S. at 101-07. Laws that
touched on the issue at hand were not enough, and
thus the common-law action could move forward. At
the same time, however, the Court foreshadowed
that federal legislation “may in time pre-empt the field
of federal common law of nuisance.” Id. at 107. Six
months after Milwaukee I, Congress passed sweeping
amendments to the Federal Water Pollution Control
Act (FWPCA), and nine years after its first decision, the
Court decided in Milwaukee II that those amendments
displaced federal common law in the area. 451 U.S. at
317-18. The Court viewed the amended statute as “a
comprehensive regulatory program supervised by an
expert administrative agency,” and it noted that under
that regulatory program “[e]very point source discharge
is prohibited unless covered by a permit.” Id. at 317-18.
This permitting requirement brought every potential
interstate water polluter within Congress’s admini-
strative scheme; any discharge had to be done with the
permission of the EPA or a qualifying state agency;
and there were enforcement options available when
polluters failed to meet the conditions of permits that
had been issued. See id. at 310-11.
Most recently, American Electric Power held “that the
Clean Air Act and the EPA actions it authorizes displace
any federal common law right to seek abatement of
carbon-dioxide emissions from fossil-fuel fired power
plants.” 131 S. Ct. at 2537. The Court found it important
that the Clean Air Act requires the EPA to identify
26 No. 10-3891
and establish performance standards for all carbon-
dioxide emitters; the statute also “provides multiple
avenues for enforcement,” which include state agencies
(operating under power delegated by EPA), the EPA
itself, criminal proceedings against violators, and
private enforcement in the event that the EPA or the
states fail to regulate emissions. If the EPA has not acted,
states and private parties may petition the agency for
a rulemaking, after which parties have a right to review
in federal court. Id. at 2537-38. The Court concluded
with the observation that “[t]he Act itself thus provides
a means to seek limits on emissions of carbon dioxide
from domestic power plants—the same relief the plain-
tiffs seek by invoking federal common law. We see no
room for a parallel track.” Id. at 2538.
For better or for worse, congressional efforts to curb
the migration of invasive species, and of invasive carp
in particular, have yet to reach the level of detail one
sees in the air or water pollution schemes. In 1990, Con-
gress passed the Aquatic Nuisance Prevention and
Control Act in an attempt to stop the spread of zebra
mussels and other nuisance species. See 16 U.S.C. §§ 4701
et seq. That statute established the Aquatic Nuisance
Species Task Force and gave it the job of studying
invasive species and implementing a program “to
prevent introduction and dispersal of aquatic nuisance
species” in the United States. See id. § 4722. In 1996, the
National Invasive Species Act amended the 1990 law
and directed the Corps and the task force to “investigate
and identify environmentally sound methods for pre-
venting and reducing the dispersal of aquatic nuisance
No. 10-3891 27
species between the Great Lakes [basin] and the Missis-
sippi River [basin] through the Chicago River Ship and
Sanitary Canal,” including any methods that could be
incorporated in the normal operation of the CAWS. Id.
§ 4722(i)(3)(A). This mandate led to the construction of
an underwater electric barrier in the Chicago Ship and
Sanitary Canal. The barrier sits just upstream of the
point where the CAWS empties into the Des Plaines
River; it is designed to deter fish from moving in either
direction through the canal. In 2003 the Corps, relying
on the continuing authority given to the Secretary of the
Army in 33 U.S.C. § 2309a, began construction of a
second barrier next to the first. The barrier projects re-
ceived an additional influx of cash from the District
of Columbia Appropriations Act of 2005, Pub. L. 108-335,
§ 345, 118 Stat. 1352 (Oct. 18, 2004). In 2007, Congress
passed the Water Resources Development Act, Pub. L.
No. 110-114, § 3061(b)(1), 121 Stat. 1121 (Nov. 8, 2007),
which allowed the Corps to upgrade its first barrier and
officially authorized the construction of the already-in-
progress second barrier. Finally, the Corps received
more money to complete a third barrier as part of the
American Reinvestment and Recovery Act of 2009.
Sections 3061(b) and (d) of the Water Resources Dev-
elopment Act of 2007, supra, instructed the Corps to
undertake two studies: a short-term examination of
how the electric barrier systems might more effec-
tively stop invasive species (this is the Efficacy Study,
which so far consists of four interim reports, see
http://www.lrc.usace.army.mil/AsianCarp/efficacy.htm);
and a long-term study of how the Mississippi and Great
28 No. 10-3891
Lakes basins might be separated on a more permanent
basis (this is the Great Lakes and Mississippi River
Interbasin Study or “GLMRIS,” see http://glmris.anl.gov).
In an appropriations bill for fiscal year 2009, Congress
provided that “the Secretary of the Army shall im-
plement measures recommended in the efficacy study,
or provided in interim reports, authorized under sec-
tion 3061 of the Water Resources Development Act of
2007 . . . with such modifications or emergency
measures as the Secretary of the Army determines to be
appropriate, to prevent aquatic nuisance species from
bypassing the Chicago Sanitary and Ship Canal Dispersal
Barrier Project referred to in that section and to prevent
aquatic nuisance species from dispersing into the Great
Lakes.” Energy and Water Development and Related
Agencies Appropriations Act 2010, Pub. L. No. 111-85,
§ 126, 123 Stat. 2845, 2853 (Oct. 28, 2009). This authority—
referred to informally as the Section 126 power—is set
to expire on September 30, 2011. Department of Defense
and Full-Year Continuing Appropriations Act 2011, Pub.
L. No. 112-10, §§ 1101(a)(2), 1104, 1106, 125 Stat. 38, 103
(Apr. 15, 2011). Add to these measures the appropria-
tion of funds so that the Corps can ensure proper
operation of the CAWS, e.g., Pub. L. No. 98-63, 97 Stat. 301,
311 (July 30, 1983); Pub. L. No. 97-88 § 107, 95 Stat. 1135,
1137 (Dec. 4, 1981); Pub. L. No. 79-525, 60 Stat. 634, 636
(July 24, 1946), and one has the whole of Congress’s
efforts to stop invasive species from moving through
the CAWS. Recent legislative proposals targeted at
halting invasive carp have failed in both Houses.
E.g., Close All Routes and Prevent Asian Carp Today Act
of 2010 (CARP ACT), H.R. 4472, S. 2946.
No. 10-3891 29
Although this legislation demonstrates that Congress
is aware of the problem of invasive species generally, and
carp in particular, it falls far short of the mark set by the
Clean Air Act or the Federal Water Pollution Control Act.
Congress has not passed any substantive statute that
speaks directly to the interstate nuisance about which
the states are complaining. Most of the laws that we
have summarized appropriate funds to the Corps for
routine maintenance of the CAWS or for the electric
barrier project. Apart from requiring the construction
of these barriers and giving the Secretary of the Army
temporary power to implement various recommenda-
tions, Congress has ordered agencies (or, more com-
monly, informal task forces composed of various execu-
tive actors) only to study the invasive species problem
and propose solutions. Beyond that, neither the Corps
nor any other agency has been empowered actively
to regulate the problem of invasive carp, and Congress
has not required any agency to establish a single
standard to deal with the problem or to take any other
action. The narrow delegation that has taken place
bears little resemblance to the regulatory power that
the EPA wields under the Clean Air Act. Tellingly, Con-
gress has not provided any enforcement mechanism
or recourse for any entity or party negatively affected
by the carp, and there is certainly no recourse to the
courts under the minimal scheme that has been estab-
lished. The district court was correct that the current
state of congressional regulation is much closer to the
situation examined in Milwaukee I—and perhaps even less
extensive than that—than the regimes reviewed in Mil-
waukee II or American Electric Power.
30 No. 10-3891
D
With these important preliminary questions out of
the way, we are at last ready to consider whether the
plaintiff states have presented enough evidence in
support of their nuisance claim to establish that they are
likely to succeed on the merits. The district court
thought that the states failed to demonstrate more than
a minimal chance of success. Before this court, the
states contend that the district court misunderstood the
elements of public nuisance. They point to the district
judge’s statement that the tort “contemplates an ac-
tive—or, at least, an imminent—threat of injury” as
evidence of that error. In their view, all they must show
to win final relief in a trial on the merits is that there
is a “significant threat” that the nuisance will occur. This
is a distinction without a difference; the district court
correctly understood the law of public nuisance. None-
theless, for different reasons we think that the district
judge may have underestimated the states’ likelihood
of success. We will elaborate on this point after a brief
review of the governing law.
1
The district court began with the definition of public
nuisance found in the Restatement (Second) of Torts,
which has been a common reference point for courts
considering cases arising under federal common law. See
Connecticut v. American Electric Power Co., Inc., 582 F.3d
309, 351 & n.28 (2d Cir. 2009), rev’d on other grounds,
American Electric Power, 131 S. Ct. 2527 (explaining that
No. 10-3891 31
“[t]he Restatement definition of public nuisance has . . .
been used in . . . federal cases involving the federal com-
mon law of nuisance . . . and the Restatement principles
have served as the backbone of state nuisance law”).
The Restatement provides that “[a] public nuisance is an
unreasonable interference with a right common to the
general public,” R ESTATEMENT (S ECOND ) OF T ORTS
§ 821B(1), and it goes on to explain that conduct meets
this standard when it interferes significantly with the
public health, safety, peace, comfort, or convenience, id.
§ 821B(2)(a). We described above the reasons why the
federal common law of public nuisance is available to
redress the type of harm that the states have alleged.
And all sides agree that if invasive carp were to achieve
a sustainable population in the Great Lakes, the environ-
mental and economic impact would qualify as an unrea-
sonable interference with a public right. As the district
court noted, the Corps and other agencies have re-
peatedly and publicly acknowledged the seriousness of
the problem. The Corps, for example, has said that
invasive carp “have the potential to damage the Great
Lakes and confluent large riverine ecosystems,” and that
it regards “[t]he prevention of an inter-basin transfer of
bighead and silver carp from the Illinois River to Lake
Michigan [as] paramount in avoiding ecologic and eco-
nomic disaster.” As a result, the central question on
the merits of the states’ public nuisance claim will be
whether the harm that the states have described is suf-
ficiently close to occurring that the courts should order
the defendants to take some new action that will be
effective to abate the public nuisance. We stress at the
32 No. 10-3891
outset an important point to which we will return:
this question is one that will be resolved after a full trial
on the merits, rather than at this preliminary stage of
the case.
A court may grant equitable relief to abate a public
nuisance that is occurring or to stop a threatened nuisance
from arising. See Tennessee Copper, 206 U.S. at 238-39
(requiring the plaintiff to show that a defendant’s
actions “cause and threaten damage”). In Missouri v.
Illinois, 200 U.S. at 518, the Court wrote that the threatened
harm underlying the nuisance claim “must be shown to
be real and immediate.” We have read the Court’s cases
to say that “[t]he elements of a claim based on the
federal common law of nuisance are simply that the
defendant is carrying on an activity that is causing an
injury or significant threat of injury to some cognizable
interest of the complainant,” Illinois v. City of Milwaukee,
599 F.2d 151, 165 (7th Cir. 1979), rev’d on other grounds,
Milwaukee II, 451 U.S. 304. Additional statements about
averting threatened nuisances appear in the Restate-
ment, see R ESTATEMENT (SECOND) T ORTS § 821B cmt. (i)
(“[F]or damages to be awarded [in public nuisance cases]
significant harm must have been actually incurred, while
for an injunction harm need only be threatened and need
not actually have been sustained at all.”); id. § 821F cmt. (b)
(“[E]ither a public or a private nuisance may be en-
joined because harm is threatened that would be signifi-
cant if it occurred.”), and in other treatises, see, e.g., 5 J.
P OMEROY, A T REATISE ON E QUITY JURISPRUDENCE AND
E QUITABLE R EMEDIES, § 1937 (§ 523), at 4398 (2d ed. 1919)
(noting that while “a mere possibility of a future nuisance
No. 10-3891 33
will not support an injunction,” relief will be warranted
when “the risk of its happening is greater than a rea-
sonable man would incur”).
The plaintiffs believe that the district court’s “im-
minent threat” requirement is inconsistent with these
principles, but we do not share that view. The district
court reproduced verbatim the elements of the claim as
we described them in Illinois v. City of Milwaukee, supra.
Its discussion of “immediacy” did nothing more
than flesh out the Court’s requirement of a “real and im-
mediate” threat in public nuisance cases. There is no
meaningful legal difference for purposes of the ultimate
resolution of a public nuisance claim between a
threatened nuisance that is “imminent” and one that is
“immediate,” “significant,” “real,” an “unreasonable risk,”
or anything similar. The job of a court considering the
merits of a public nuisance claim is simply to deter-
mine whether the activity complained of is a nuisance
and, if so, whether it is sufficiently close to occurring that
equitable relief is necessary to prevent it from happening.
2
We part company with the district court when it comes
to the assessment of the states’ likelihood of success on
the merits. Here we think it critical to bear in mind the
difference between preliminary or interim relief, on the
one hand, and permanent relief, on the other. The princi-
ples that we just reviewed relate to the ultimate outcome
of a public nuisance proceeding. This case has not
yet reached that stage, and one consequence of its prelimi-
34 No. 10-3891
nary posture is that the states were not required to
prove that they will ultimately win on the merits in
order to secure preliminary relief.
“The propriety of preliminary relief and resolution of
the merits are of course significantly different issues.”
Parents Involved in Cmty. Sch. v. Seattle Sch. Dist. No. 1, 551
U.S. 701, 721 n.10 (2007) (internal quotation marks omit-
ted). This is the reason why findings made at the pre-
liminary injunction stage do not bind the district court
as the case progresses. Cf. Guaranty Bank v. Chubb Corp.,
538 F.3d 587, 591 (7th Cir. 2008). The most significant
difference between the preliminary injunction phase
and the merits phase is that a plaintiff in the former
position needs only to show “a likelihood of success on
the merits rather than actual success.” Amoco Prod. Co. v.
Village of Gambell, 480 U.S. 531, 546 n.12 (1987); cf. Chathas
v. Local 134 Int’l Bhd. of Elec. Workers, 233 F.3d 508, 513
(7th Cir. 2000) (“A plaintiff cannot obtain a permanent
injunction merely on a showing that he is likely to win
when and if the merits are adjudicated.”). In some cases,
it is necessary to expedite an ultimate decision, and so
courts sometimes consolidate the preliminary injunction
hearing with the trial on the merits. See F ED. R. C IV.
P. 65(a)(2). But where such consolidation has not taken
place—and it has not here—and the question is the pro-
priety of preliminary relief, the Supreme Court has
warned against “improperly equat[ing] ‘likelihood of
success’ with ‘success’ . . . .” University of Texas v.
Camenisch, 451 U.S. 390, 394 (1981); see also Meridian Mut.
Ins. Co. v. Meridian Ins. Group, Inc., 128 F.3d 1111, 1119
(7th Cir. 1997). This is in keeping with the often-repeated
No. 10-3891 35
rule that the threshold for establishing likelihood of
success is low. E.g., Cooper v. Salazar, 196 F.3d 809, 813 (7th
Cir. 1999); Brunswick Corp. v. Jones, 784 F.2d 271, 275 (7th
Cir. 1986).
We are concerned that the district court here may
have lost sight of this distinction. By applying directly
the law of public nuisance, the judge seems to have
required the plaintiff states actually to show that they
were entitled to permanent injunctive relief during the
preliminary injunction hearing. The court concluded its
discussion of the threat posed by invasive carp, for ex-
ample, by saying that the states “ha[d] not made a con-
vincing case” that the fish had pushed into the CAWS
in significant numbers; and it said that the plaintiffs
had not “shown that the fish [are] anywhere near . . .
establishing a population in Lake Michigan.” Because
the states had not yet shown that the threat of nuisance
was great enough in the final analysis to warrant an
injunction to abate it, the district court seems to have
assumed that they had also failed to show enough to
obtain preliminary relief. To demonstrate the requisite
likelihood of success, however, the states needed only
to present a claim plausible enough that (if the other
preliminary injunction factors cut in their favor) the
entry of a preliminary injunction would be an appro-
priate step. The preliminary injunction, after all, is often
seen as a way to maintain the status quo until merits
issues can be resolved at trial. By moving too quickly
to the underlying merits, the district court required too
much of the plaintiffs and, correspondingly, gave too
36 No. 10-3891
little weight to the strength of their claim at this stage
of the case.
3
We also question the inferences drawn by the dis-
trict court from the facts that it so carefully found after
evaluating five days of hearings, which included the
testimony of expert witnesses and volumes of written
materials on complex scientific and engineering issues.
There is very little to criticize about the court’s factual
findings themselves. For instance, the district judge’s
decision to admit the expert testimony of Dr. David
Lodge, who has been hired by the Corps and who
testified for the states at the preliminary injunction
hearing about his efforts to track invasive carp through
the use of environmental DNA (eDNA) testing, reflects
a proper application of Federal Rule of Evidence 702.
(We agree that any lack of peer review of Dr. Lodge’s
work would go to the weight of his testimony, not to
the court’s ability to consider it. Moreover, the situation
will be different at the merits phase, given Dr. Lodge’s
recent publication of his research. See Christopher L. Jerde,
Andrew R. Mahon, W. Lindsay Chadderton & David M.
Lodge, “Sight Unseen” Detection of Rare Aquatic Species
Using Environmental DNA, 4 Conservation Letters 150
(April/May 2011).) We also see nothing to criticize in
the district court’s assessment that the electric barriers
built by the Corps near the intersection of the Chicago
Sanitary and Ship Canal and the Des Plaines River seem
to have at least some deterrent effect on the movement
No. 10-3891 37
of invasive carp toward the Great Lakes. In addition,
we consider it significant, as the district judge did, that
efforts to detect carp by techniques including netting, so-
called electrofishing, and rotenone poisoning, have led
to few signs of the carp.
Along the same lines, the district court was right to
take into account the results of eDNA testing. Despite
its skepticism about the reliability of the technique and
its concern that the state of eDNA science “did not permit
a reasonable inference that live Asian carp are in the
[CAWS] . . . in numbers that present an imminent
threat,” the court acknowledged that the eDNA evidence
lent some support to the conclusion that there may be
invasive carp above (i.e., lakeside of) the Corps’s electric
barriers. Although we are less skeptical of the science
than the district court, we too believe that caution in
drawing inferences from the existence of carp DNA in
the water is warranted. The eDNA technique, which
tests water samples for markers matching a particular
species, has a number of shortcomings: it is difficult, if
not impossible, to know definitively whether a positive
result signals a living specimen above the barrier (DNA
may be shed by a dead or distant fish); a positive test
does not reveal the number of live fish; and negative
results do not necessarily signal the absence of carp.
Efforts to corroborate eDNA results with traditional
methods of capturing fish have not been successful
thus far. On the other hand, the evidence is worth some-
thing. The eDNA technique detects carp when the fish
are present in small numbers and in situations where
the other fishing methods we described above might
38 No. 10-3891
scare them away or simply miss them, and the large
number of negative test results make sense given the
sensitivity of the technique. In addition, the Corps and
other agencies have voted with their feet: they have
been using eDNA tests to manage the invasive carp
crisis, and they have said that this testing will continue.
(This is undoubtedly why the private intervenor-defen-
dants are the primary critics of this methodology.) If
the tests are good enough for expert agencies, it is hard
to see why we should flatly forbid their consideration.
A January 2011 report on eDNA sampling conducted in
2010 showed positive eDNA results in approximately a
dozen locations throughout the CAWS, and experts have
opined that these results indicate the presence of carp at
multiple locations in the CAWS. On July 29, 2011, federal
officials announced that they would begin daily efforts
to find invasive carp around Lake Calumet, after multiple
rounds of testing revealed carp DNA in that area. See
Asian Carp Regional Coordinating Committee, Press
Release, July 29, 2011, http://asiancarp.org/news/asian-
carp-regional-coordinating-committee-to-begin-intensive-
monitoring-in-lake-calumet-in-response-to-environmental-
dna-results; Tammy Webber, Feds to Step Up Hunt for
Asian Carp Near Chicago, Chicago Tribune, July 29, 2011.
The district court thought that this evidence, in combina-
tion with the discovery of two invasive carp specimens
(one dead and one living) in the CAWS, supported a theory
that invasive carp are present in the CAWS in “low num-
bers.” This conclusion was reasonable. The carp may
even be present in greater numbers, but for present
purposes we do not need any more precision.
No. 10-3891 39
Our greatest hesitation with respect to the district
court’s findings is over its conclusion that “it is far from
certain that Asian carp can survive and reproduce in
the Great Lakes.” Given the record that was before
Judge Dow, this prediction may have been sound at the
time he ruled. The situation has been evolving rapidly
since the preliminary injunction hearing, however, and
so we think it worth mentioning that the newest
publicly available evidence suggests that when and if
the time comes, the carp are unlikely to have trouble
establishing themselves in the Great Lakes. Before the
district court there was testimony reflecting great uncer-
tainty about how easily the carp could live and
reproduce in this new habitat. A species typically
requires multiple introductions before it takes root in a
new ecosystem, and there has been a substantial debate,
reflected in the literature, about whether the food supply
and other features of the Great Lakes could support
the carp. See generally Sandra L. Cooke & Walter R. Hill,
Can Filter-Feeding Asian Carp Invade the Laurentian Great
Lakes? A Bioenergetic Modelling Exercise, 55 Freshwater
Biology 2138 (2010); Cynthia S. Kolar & David M. Lodge,
Ecological Predictions and Risk Assessment for Alien Fishes
in North America, 298 Science 1233 (2002). On April 28,
2011, however, the Obama Administration presented
two pieces of what it called “bad news” at a meeting in
Chicago on invasive carp: first, it said that while it was
once thought that the carp could not establish breeding
populations in Lake Michigan because of the low levels
of plankton (the carp’s normal food source) in the water,
new evidence suggests that the fish will happily switch
40 No. 10-3891
from eating plankton to consuming the green algae that
now covers the lake floor (thanks to another invasive
species, the zebra mussel); and (2) while experts had
thought the carp need coastal rivers between 30 and
60 miles long to spawn, it turns out they can make do
with much shorter breeding grounds. See, e.g., Asian Carp
Possibly Hardier than Once Thought, Chicago Tribune,
Apr. 28, 2011. At this point, therefore, we must assume
that once in the Great Lakes, the invasive carp would
make it their home.
We need not explore the factual record further. As
we have said, our review of the district court’s findings
is deferential, and we see nothing that demands cor-
rection. The critical point is that this record is not a
static thing. The district court will undoubtedly have
more evidence before it when it is time to rule on the
request for a permanent injunction, and we are
confident that the court will keep its mind open to the
implications of any new information. For purposes of
assessing the need for preliminary relief, the court relied
on its findings that at best a limited number of invasive
carp were present in the CAWS and its observation that
the so-called invasion front was approximately 30 miles
downstream of the CAWS (60 miles from Lake Michigan)
as of the spring of 2009. On this basis, it reached the
conclusion that while the potential for damage to the
Great Lakes is high, the problem had not advanced far
enough to present a threat to the plaintiff states. From
that it drew the conclusion that the states had shown
little likelihood of success on the merits.
No. 10-3891 41
It is that final step that gives us trouble. As the
district court rightly noted, the magnitude of the
potential harm here is tremendous, and the risk that this
harm will come to pass may be growing with every
passing day. (It certainly has grown since the ill-fated
day around 1970 when the carp escaped from various
aquaculture facilities and began their march up the Miss-
issippi River. See generally Wisconsin Dep’t of Nat. Res.,
Bighead and Silver Carp (Hypophthalmichthys nobilis and H.
molitrix), http://dnr.wi.gov/invasives/fact/asian_carp.htm.)
Given the magnitude of the harm, we are inclined to
give the benefit of the doubt to the states on the question
whether they have shown enough of a risk of nuisance
to satisfy the likelihood-of-success requirement at this
preliminary stage. See Van De Sande v. Van De Sande,
431 F.3d 567, 570 (7th Cir. 2005) (“The gravity of a risk
involves not only the probability of harm, but also the
magnitude of the harm if the probability materializes.”)
(citing United States v. Carroll Towing Co., 159 F.2d 169, 173
(2d Cir. 1947)). In addition, the nature of the threat—an
ecological harm—suggests that a broader perspective
on the problem might be necessary. It is hard to see
60 miles of separation between the carp invasion front
and the Great Lakes (and remember this was the
estimated distance more than two years ago) as a par-
ticularly safe margin, even with functioning electric
barriers to deter fish and efforts to reduce propagule
pressure (the volume of invasive carp in the water down-
stream of the front). It is especially chilling to recall that
in just 40 years the fish have migrated all the way from
the lower Mississippi River to within striking distance
42 No. 10-3891
of the lakes and have come to dominate the ecosystem
in the process. Commercial harvesting of carp in the
Mississippi basin increased from just over five tons to
55 tons in the three-year period from 1994 to 1997; there
is evidence that by 1999 invasive carp made up 97% of
the Mississippi’s biomass; and as of 2007 commercial
fishers were catching 12 tons of invasive carp each day.
These numbers are sobering even apart from the hints
that some of the fish may have made it into the CAWS
already.
In our view, the proper inference to draw from the
evidence is that invasive carp are knocking on the door
to the Great Lakes. We need not wait to see fish being
pulled from the mouth of the Chicago River every day
before concluding that a threat of a nuisance exists. It is
enough that the threat is substantial and that it may be
increasing with each day that passes. Unlike many nui-
sances that can be eliminated after they are discovered,
this one in all likelihood cannot be. The fact that it
would be impossible to un-ring the bell in this case is
another reason to be more open to a conclusion that the
threat is real. In our view, the plaintiff states presented
enough evidence to establish a good or even sub-
stantial likelihood of success on the merits of their
public nuisance claim.
III
Before moving on to the other preliminary injunction
factors, there are some particular questions about the
APA claim against the Corps that we must address. We
No. 10-3891 43
turn again to § 702 of the APA, which authorizes a suit
by “[a] person suffering legal wrong because of agency
action, or adversely affected or aggrieved by agency
action within the meaning of a relevant statute.” 5 U.S.C.
§ 702. A reviewing court is required to “compel agency
action unlawfully withheld or unseasonably delayed,”
5 U.S.C. § 706(1), and to “set aside agency action . . . found
to be . . . arbitrary, capricious, an abuse of discretion, or
otherwise not in accordance with law,” id. § 706(2)(A). The
states do not ask us to compel the Corps to take action, at
least as far as § 706(1) is concerned. Norton v. Southern
Utah Wilderness Alliance, 542 U.S. 55, 64 (2004), explains
that “a claim under § 706(1) can proceed only where a
plaintiff asserts that an agency failed to take a discrete
agency action that it is required to take”; the states have
named no action that they think the agency is required to
take. We understand the states’ argument as a request
to set aside agency action that they regard as
unlawful within the meaning of § 706(2)(A).
The obvious starting point is to identify the final
Corps action that the states assert has affected them.
See 5 U.S.C. § 704; Lujan v. National Wildlife Fed’n, 497
U.S. 871, 882 (1990). The states contend that five such
actions fit the bill. They say that the Corps’s (1) opera-
tion of the CAWS in a manner that will let invasive
carp into Lake Michigan, (2) reliance on ineffective
electric barriers, (3) use of locks in areas where living
and dead carp have been found, (4) denial of the states’
requests for additional relief, and (5) implementation of
recommendations contained in the Corps’s third interim
report (which is part of the Efficacy Study we discussed
44 No. 10-3891
in connection with our analysis of displacement, supra)
are all final agency actions. The district court equivocated
on the issue, but it seems to have agreed with the states
in the end.
There is a good chance that most of the “actions” named
by the states are not “final agency actions” for purposes
of the APA. “Agency action” is defined as “the whole or
a part of an agency rule, order, license, sanction, relief or
the equivalent or denial thereof, or failure to act,” 5 U.S.C.
§ 551(13). The Supreme Court has explained that these
categories all “involve circumscribed, discrete agency
actions,” Norton, 542 U.S. at 62. Agency action is “final”
when it marks the consummation of the agency’s
decisionmaking process and determines legal rights or
obligations. Bennett v. Spear, 520 U.S. 154, 177-78 (1997); see
also Western Illinois Home Health Care, Inc. v. Herman,
150 F.3d 659, 662 (7th Cir. 1998) (citing Franklin v. Massa-
chusetts, 505 U.S. 788 (1992), for the proposition that
“[t]he core question is whether the agency has com-
pleted its decisionmaking process, and whether the
result of that process is one that will directly affect
the parties”). Applying these standards, we cannot see
why any of the “actions” that are numbered 1 through 4
on the states’ list of complaints above should be con-
sidered final agency action. Most of the four “actions” are
not discrete at all; and those that might be so classified
do not represent the final outcome of any decision-
making process by the Corps. The Corps’s effort to im-
plement its third interim report—which recommended
the installation of screens over two gates that control
water flow between the CAWS and Lake Michigan but
No. 10-3891 45
which otherwise called for normal operation of lake-
facing locks—is the only activity that may be suitable
for an APA challenge. We need not evaluate that claim
in any detail, however, because it is part of the states’
larger request for relief based on the common law of
public nuisance.
Two types of plaintiffs are given a right of review in
§ 702: those suffering a “legal wrong,” and those “ad-
versely affected or aggrieved by agency action within
the meaning of a relevant statute.” In their briefs in this
court, the states have not pointed to a single statute
against which one might judge the Corps’s behavior. (This
is not surprising, given the dearth of pertinent federal
legislation that we discussed in connection with displace-
ment.) The Corps submits that this means that the
states have no APA claim; the states respond their
APA claim is “free-standing.” Neither answer is satis-
factory. We know that the states have not alleged that
the Corps’s actions failed to comply with some
statutory provision, and so they must instead be
asserting that they have suffered a “legal wrong” because
of those actions. The only legal wrong that comes to
mind, however, is the infliction of a common-law public
nuisance. See Lujan, 497 U.S. at 883 (distinguishing be-
tween legal wrongs and the failure of an agency to
comply with a statutory provision); Tennessee Electric
Power Co. v. Tennessee Valley Authority, 306 U.S. 118, 137
(1939) (explaining that “legal wrong” includes tortious
invasions and interferences with property and contractual
rights). See generally Antonin Scalia, The Doctrine of
Standing as an Essential Element of the Separation of Powers,
46 No. 10-3891
17 S UFFOLK U. L. R EV. 881, 887-90 (1983) (discussing
the use of the term “legal wrong” in the APA and ex-
plaining that it “could only mean a wrong already cog-
nizable in the courts”). The result is that the states’ APA
claim against the Corps sinks or swims (so to speak)
with its public nuisance theory. Because they are indis-
tinguishable, we address only the latter from this point on.
IV
To satisfy the second threshold requirement for pre-
liminary injunctive relief, the states must establish that
irreparable harm is likely without an injunction. Judge v.
Quinn, 612 F.3d 537, 557 (7th Cir. 2010). In the district
court’s view, this issue was the same as the question
whether the states had shown a likelihood of success on
the merits of their public nuisance claim. The states
contend that it was error to conflate these inquiries.
They are right. In this case, for example, the likelihood
of success on the merits focuses on the threat of a
nuisance, while the irreparable harm is concerned with
the ability to correct that nuisance if it is created. Not
every nuisance will give rise to irreparable harm. These
two steps of the preliminary injunction analysis thus
play different roles. The likelihood of success on the
merits is an early measurement of the quality of the
underlying lawsuit, while the likelihood of irreparable
harm takes into account how urgent the need for
equitable relief really is. Typically, these lines of inquiry
will have some overlap, but they should not be treated
as the same. With that in mind, we realize that the
No. 10-3891 47
same evidence will inform both steps of the preliminary
injunction analysis in this case. As long as the distinc-
tions we have just mentioned remain clear, there is no
harm in analyzing all of the evidence once rather
than twice. As a result, the states’ criticism of the district
court is largely academic and provides no reason to
reverse that court’s decision.
Putting theory to one side, we have very little trouble
concluding that the environmental and economic harm
that the states have shown might come to pass would be
genuinely irreparable if it did occur. The district court
implied that this was the case when it discussed the
magnitude of the potential harm. Last year in Supreme
Court filings related to this litigation, the United States
explained in a memorandum that it agreed with
Michigan “that allowing a reproducing population of
Asian carp to establish itself in Lake Michigan likely
would be an irreparable injury.” Memorandum in Op-
position of the United States, at 43, Original Nos. 1, 2,
and 3, http://www.supremecourt.gov/SpecMastRpt/US_
Memorandum_in_Opposition.pdf; see also id. at 47 (calling
the harm “grave and irreparable”). All of the other
parties seem to agree with this view. (To the extent that
the defendants argue that there is no irreparable harm
because the carp cannot establish a breeding population
in Lake Michigan, they are avoiding the key question:
what if the fish did establish a successful breeding
group?) This near-unanimity on the question of ir-
reparable injury makes sense. “Environmental injury, by
its nature, can seldom be adequately remedied by
money damages and is often permanent or at least of
48 No. 10-3891
long duration, i.e., irreparable.” Amoco Prod., 480 U.S. at
545; Sierra Club v. Franklin County Power of Illinois, LLC, 546
F.3d 918, 936 (7th Cir. 2008). Harms like those the states
allege here are irreparable because they are difficult—if
not impossible—to reverse. See Hollingsworth v. Perry,
130 S. Ct. 705, 712 (2010) (per curiam).
For preliminary relief to be granted, the irreparable
harm must also be likely. That is, there must be more
than a mere possibility that the harm will come to pass,
Winter, 555 U.S. at 21-23, but the alleged harm need not
be occurring or be certain to occur before a court may
grant relief, United States v. W.T. Grant Co., 345 U.S. 629,
633 (1953); United States v. Oregon State Med. Soc’y, 343
U.S. 326, 333 (1952); Bath Indus., Inc. v. Blot, 427 F.2d 97,
111 (7th Cir. 1970). Commentators describe the required
level of certainty this way: “[A] preliminary injunction
will not be issued simply to prevent the possibility of
some remote future injury. A presently existing actual
threat must be shown. However, the injury need not
have been inflicted when application is made or be
certain to occur.” 11A C HARLES A LAN W RIGHT, ET AL.,
F EDERAL P RACTICE AND P ROCEDURE § 2948.1, at 154-55
(2d ed. 1995). Because the district court analyzed
likelihood of success on the merits at the same time as it
assessed the danger of irreparable harm, all of the res-
ervations we had about the inferences drawn by the
district court in the former context apply with equal
force here.
As we have already pointed out, no one knows whether
this irreparable harm will come to pass. The intense
No. 10-3891 49
factual dispute we are witnessing here about the rate
at which invasive carp are progressing makes evaluating
its likelihood even more tricky. In our view, the district
court required a level of proof too close to certainty
when it assessed the danger of invasive carp escaping
into Lake Michigan. Given the dire nature of the harm
posed by the carp and their close proximity to the CAWS,
we again will give the plaintiff states the benefit of the
doubt. Just as they produced enough evidence to
establish a likelihood of success on the merits war-
ranting injunctive relief, so too have they shown, to
the degree necessary for preliminary relief, that it is
likely that irreparable harm will come to pass. This sets
the stage for the dispositive issue: how must the harms
the states have identified be balanced against those that
the defendants will suffer should an injunction be granted?
V
The balancing process to which we now turn is a
classic part of any preliminary injunction inquiry. See
Winter, 555 U.S. at 24 (“A preliminary injunction is an
extraordinary remedy never awarded as of right. In each
case, courts must balance the competing claims of injury
and must consider the effect on each party of the
granting or withholding of the requested relief.”) (internal
quotation marks and citations omitted). How much of
the danger forecast by the states would be avoided by
the particular injunction they have asked for? And what
harm would the injunction impose on the defendants?
Typically, after we balance these party-specific equities,
50 No. 10-3891
we evaluate whether the injunction would advance or
impede the public interest. See, e.g., Ferrell v. U.S. Dep’t
of Hous. and Urban Dev., 186 F.3d 805, 811 (7th Cir. 1999).
That additional analysis is not necessary in this case,
however, because the parties themselves, with the ex-
ception of two intervenors, are governmental entities
that represent the interests of the public.
When it appears that preliminary relief may be bur-
densome, the Supreme Court has instructed courts to be
careful as they balance the competing interests. Winter,
555 U.S. at 27; see also Kartman v. State Farm Mut. Auto.
Ins. Co., 634 F.3d 883, 892 (7th Cir. 2011). In light of the
multifarious ideas the states have for an injunction in
this case, there can be no doubt that caution must be
our word of the day. Even if a plaintiff’s suit appears
to have merit, an injunction should not necessarily issue
if the harm to the defendant would substantially out-
weigh the benefit to the plaintiff. MacDonald v. Chicago
Park Dist., 132 F.3d 355, 357 (7th Cir. 1997).
In the end we conclude that a preliminary injunction
would cause significantly more harm that it would pre-
vent. We reach this result for two reasons, which we
summarize here before explaining the balance of harms
in more detail. First, there are a number of problems
with various line items in the plaintiffs’ proposed
package of relief. Taken together, these problems leave
us doubting whether the proposed injunction would
reduce by a significant amount the risk that invasive
carp will gain a foothold in the Great Lakes between
now and the time that a full trial on the merits is com-
No. 10-3891 51
pleted. It is clear, on the other side, that the requested
measures would impose substantial costs on the defen-
dants and the public interests they represent, as well as
added expenses for commerce, recreation, and tourism.
Second, as circumstances currently stand, there is a
more fundamental reason that the states’ requested
injunction is unlikely to prevent much harm and actually
may impose costs. The courts would not be acting
alone. As we have explained, there is a powerful array
of expert federal and state actors that are engaged in a
monumental effort to stop invasive carp from entering
the Great Lakes. The last thing we need is an injunction
operating at cross-purposes with their efforts or
imposing needless transactional costs that divert scarce
resources from science to bureaucracy. Furthermore,
from an institutional perspective courts are compara-
tively ill situated to solve this type of problem. The
balance of harms favors the defendants and the public
interests they represent to such an extent that we
conclude that the district court’s decision to deny pre-
liminary relief was not an abuse of discretion.
A
1
It is best to begin by trying to understand precisely
what preliminary relief the states would like. As the
district court noted, their request has evolved as the
case has moved forward. Indeed, their position has
shifted even between their opening brief in this court and
oral argument. The moving nature of the target compli-
52 No. 10-3891
cates our job of evaluating the propriety of injunctive
relief. Moreover, their request has been phrased at a
high level of generality. They have given us the broad
strokes of additional steps they would like us to order
the defendants to take, but they have not furnished
many details about how this relief would be imple-
mented, on what schedule, at what cost, and on whose
nickel. From time to time the states urge that the
injunctive measures should be “consistent with public
health and safety,” but they do not say what precisely
that means. This vagueness is unhelpful; it stands as an
obstacle to the entry of an injunction that will satisfy
Federal Rule of Civil Procedure 65(d). See PMC, Inc. v.
Sherwin-Williams Co., 151 F.3d 610, 619-20 (7th Cir. 1998);
see also Patriot Homes, Inc. v. Forest River Hous., Inc.,
512 F.3d 412, 414-15 (7th Cir. 2008). When a plaintiff
seeks relief of the type the states ask for here, we have
required a more specific plan about the measures to be
taken and the costs of implementing those measures.
See Jordan v. Wolke, 593 F.2d 772, 774-75 (7th Cir. 1978).
At this time, it is our understanding that the states
believe that they are entitled to a preliminary injunction
that would require the defendants to take these five steps:
a. Closing the Locks. Close and stop operating the
locks at the Chicago River Controlling Works (the
Controlling Works) and the O’Brien Lock and Dam
(O’Brien), which sit at two of the five points of
contact between the CAWS and Lake Michigan;
b. Screens over Sluice Gates. Install nine additional
screens over sluice gates that are used to control water
No. 10-3891 53
flow between the CAWS and the lake at the Control-
ling Works, O’Brien, and the Wilmette Pumping
Station, a third contact point with Lake Michigan;
c. Block Nets in the Rivers. Place block nets to stop
fish in the Little Calumet River, which connects the
CAWS to the lake at the Burns Small Boat Harbor in
Indiana, and if necessary in the Grand Calumet
River, which runs between the CAWS and the
Indiana Harbor and Canal (Burns Harbor and Indiana
Harbor are last of the five contact points between
the CAWS and Lake Michigan);
d. Rotenone Poisoning. Use rotenone to poison fish in
the CAWS, especially in areas north of O’Brien.
e. Accelerating GLMRIS. Finish the part of the Great
Lakes and Mississippi River Interbasin Study that
relates to the CAWS, which Congress called for in the
Water Resources Development Act of 2007, within
18 months.
The states have made two additional requests that do
not require discussion. They say that the defendants
should use the best methods to stop, capture, and kill
carp that are present in the CAWS. We see this as a
more general statement of the specific measures we
have just outlined. In addition, the states want the de-
fendants to continue using monitoring techniques, in-
cluding eDNA testing, to search for invasive carp. But
the Corps and the other agencies working on this prob-
lem are continuing eDNA monitoring efforts. In July
2011, for example, three rounds of positive eDNA testing
results led to a four-day hunt for invasive carp (none
54 No. 10-3891
was found). This request asks for steps already being
taken, and so we will not discuss it further.
2
Before we discuss the harm and benefit of the prelimi-
nary relief the states request, we must point out an error
in the states’ view of how the harms should be weighed.
The states say that any harm the defendants might suffer
because of the injunction pales “in comparison to the
grave and truly irreparable harm that will occur if Asian
carp establish a breeding population in the Great Lakes.”
But that is not the correct measure of the harm avoided
by the states’ proposed injunction. The states assume,
without providing much explanation, that preliminary
relief would stop invasive carp from ever reaching the
Great Lakes. While that may be the effect that a perfectly
designed permanent injunction would have, it is not
an accurate measure of the harm that would be avoided
by the states’ proposed preliminary injunction. At this
early point, the question is to what extent would the
proposed measures decrease the risk of invasive carp
establishing themselves in the Great Lakes between
now and when the litigation concludes? Stepping back
from the subject matter of this litigation, we note that
in addition to the CAWS, the Corps has identified a total
of 18 places in Minnesota, Wisconsin, Indiana, Ohio, and
New York where invasive carp could move from the
Mississippi basin into the Great Lakes. These pathways
outside of the CAWS necessarily reduce the likelihood
that the states’ preliminary injunction will prevent carp
No. 10-3891 55
from establishing themselves in the Great Lakes, because
the states’ proposed measures say nothing about these
alternate routes. Even focusing exclusively on the
CAWS, the states overlook similar limitations inherent
in the steps they are proposing—limitations that would
reduce the effectiveness of preliminary relief, as we
now explain.
a. Closing the Locks. If the locks at the Controlling Works
and O’Brien are closed, the states concede that the
closure need not be permanent or unqualified; instead,
they say, the locks may be opened if closure would put
public health or safety at risk. We are not sure how that
would work. The City of Chicago says that police and
fire services use the locks routinely, as do Coast Guard
boats. At one point, the states agreed that passage
for emergency boats through the locks was needed for
public safety. That sounds reasonable to us. Now, how-
ever, their injunction would allow the defendants to
open the locks only when the District needs to release
water from the CAWS into the lake to control
flooding (during so-called “reversal” operations). The
states’ proposed injunction is made more effective by
keeping the locks closed to all boat traffic, but in so
doing, it increases the cost to emergency services. Even
in its current iteration, the efficacy of the states’ plan
for closing the locks is compromised because any
flooding that would require the defendants to conduct
reversal operations decreases the chances that the carp
will be stopped—when the locks are open, water pours
out of the CAWS and into Lake Michigan. (This hap-
pened most recently on July 24, 2011, after nearly seven
56 No. 10-3891
inches of rain fell in only two hours, see Michelle
Gallardo, 2 Locks Opened During Record Rainfall, Chicago
Tribune, July 25, 2011, http://abclocal.go.com/wls/story?
section=news/local&id=8270514. It also happened exactly
one year before, on July 24, 2010.) A related complication
concerns how effectively the locks stop fish even when
they are closed. By most accounts, a watertight closure
would require bulkheads to be installed on the locks.
Without bulkheads, fish might slip through small open-
ings. The states have been less than explicit about
whether their ideal injunction would require bulkheads,
but if it would, then all the risks of flooding come right
back into the equation. Bulkheads take time to install
and remove, which means that it would be very difficult
to respond quickly to floods. In short, this aspect of the
states’ requested relief puts them into a bind: the risk of
carp migration is reduced the most by closing the locks
permanently with bulkheads; but that measure, as the
states recognize, would dramatically escalate the costs
imposed by flooding. While keeping the locks closed
more often no doubt reduces the risk of fish migrating
into Lake Michigan, it does not bring it down to zero.
And this unquantified reduction in risk comes with an
increased immediate burden on public health and safety
measures.
b. Screens over Sluice Gates. The states encounter
similar problems with their request that the defendants
screen off nine additional sluice gates. The District
operates these huge gates, which open and close to
adjust the rate of water flow, as part of its diversion
effort—the process of drawing water out of Lake
No. 10-3891 57
Michigan and into the CAWS to maintain navigability
and water quality. In addition, when heavy rains occur,
sluice gates (like the locks) are opened to let water from
the CAWS into the lake. There are eight sluice gates at
the Controlling Works, four at O’Brien, and one in
Wilmette. To prevent the migration of adult carp, the
District already has installed four screens over sluice
gates: two at the Controlling Works and two at O’Brien.
The District uses the four screened-off gates for diver-
sion; the other nine remain closed except during flooding.
Initially, the states wanted to force the defendants to
close all of the gates, except when public health or safety
might be harmed. They have revised that request so
that now they ask for screens over the nine remaining
sluice gates at these sites. This request would mitigate
the risk of carp migration only (at best) during floods, for
at other times the gates, unlike the locks, are closed
anyway. Further reducing the effectiveness of this
measure is the fact that in some flooding incidents
where additional sluice gates must be opened, the locks
must be opened as well. Screens over additional sluice
gates would not do much good if fish could swim
through open locks. Finally, all available evidence
suggests that it will take a long time for the District
to acquire additional property, to research feasible
options for a system of screens that will not become
clogged with debris during flooding, and to build those
screens. This means that this portion of the states’ prelimi-
nary injunction might not even be in place before the
full trial on the merits has concluded. For all of these
reasons, we think that installing screens over sluice
58 No. 10-3891
gates will have at most a tiny effect on the odds of
invasive carp making it to Lake Michigan.
c. Block Nets in the Rivers. The prospect of placing block
nets in the Little Calumet and Grand Calumet Rivers
strikes us as potentially the most effective element of the
proposed relief. At the time of oral argument, the states
asked that the Corps place block nets only in the Little
Calumet River; at that point, a cofferdam in the Grand
Calumet River prevented fish migration and alleviated
the need for nets there. We will assume that were this
dam removed, the states would ask the Corps to place
nets in the Grand Calumet River as well. The Corps,
however, has said that it is already looking at the possi-
bility of installing nets in both waterways, but that it is
concerned that flooding will increase as debris becomes
caught in the nets. The states respond that block nets
could be cut free and replaced with new nets if risks of
flooding materialized. All of the parties are vague about
the possibilities and implications of this plan. At this
stage, it is enough to say that this step seems more prom-
ising than others when it comes to mitigating the risk
that fish will appear in Lake Michigan. We take the
Corps at its word that this option is under serious con-
sideration and would be implemented if and when a
feasible plan can be developed.
d. Rotenone Poisoning. In contrast to the block net
idea, the suggestion that the Corps use rotenone to
poison fish in the CAWS seems untenable to us.
Rotenone is a chemical that acts as a piscicide when it
is released in a body of water. Though humans would
No. 10-3891 59
not digest much of it if it were ingested, rotenone enters
the bloodstream of a fish through the gills, causing death
quickly. Rotenone dumped into a river kills the vast
majority of fish living there; when dead, they usually
float to the surface. The poison generally is less
dangerous to other animals, but it is toxic and its toxicity
varies depending on the species. See generally Cornell
University, Resource Guide for Organic Insect and
Disease Management, Material Fact Sheets—Rotenone,
h t t p : / / w e b . p p p m b . c a l s . c o r n e l l . e d u / r e s o u rc e g u id e /
mfs/11rotenone.php. It is unclear just how the states’
proposal for rotenone use differs from what the Corps
is already doing in the CAWS. We know that the
states would like poison to be applied near O’Brien,
but there is no indication how often or where else it
might be used. In May 2010, the Corps and other
agencies used the poison to search for fish in a two-mile
stretch of the Little Calumet River. Dozens of tons of fish
were killed, and no specimens of invasive carp were
found. While poisoning may be an effective way to
search for elusive carp in some circumstances, the record
does not explain why ordering the Corps to poison the
CAWS on a regular basis would be a sound step toward
reducing the risk that invasive carp will migrate into
the Great Lakes.
e. Accelerating GLMRIS. That brings us to the aspect
of the proposed injunction that would require the Corps
to accelerate its long-term study of ways in which it
might permanently prevent the migration of invasive
species (including, but not limited to, the carp) between
the Great Lakes and the Mississippi basins. The states
60 No. 10-3891
raise a side issue here, saying that the district court
erred when it denied their request to expedite GLMRIS
because it failed to make the findings required by
Federal Rule of Civil Procedure 52(a)(2). The argument
is frivolous. The district court explained its reasons for
denying all of the relief that the states sought. The
court had—and will continue to have as the case
moves forward—the power to grant or deny equitable
measures either in whole or in part. It did not need to
discuss every facet of the relief requested.
According to the Corps, GLMRIS examines every poten-
tial pathway between the two watersheds and proposes
solutions to stop migration through each one. Examina-
tion of the CAWS, which the Corps intends to finish by
2015, is just one portion of the study. The Corps adds
that it has the power to implement solutions that are
devised as the study progresses. The states would like the
court to order the Corps to finish the CAWS portion of
GLMRIS within 18 months. They are not the only ones
who have criticized the study for taking too long; the
City of Chicago and others have as well. See, e.g., Dan
Egan, Chicago Urges Army Corps to Report on Carp Sooner,
Milwaukee Journal Sentinel, Apr. 10, 2011, http://
www.jsonline.com/news/wisconsin/119547049.html. It may
well be that faster action is appropriate if possible; and,
as the Corps conceded during oral argument, it may be
necessary for the Corps to implement measures devised
through GLMRIS on a rolling basis. But we do not see
how a preliminary injunction that would essentially ask
the Corps to study harder and think faster would
No. 10-3891 61
reduce the odds that invasive carp will establish them-
selves in the short term.
When we take all five aspects of the states’ proposed
injunction together, we can say only that there is some
evidence that the relief sought would reduce by an unde-
fined amount the risk of carp establishing a breeding
population in the Great Lakes. It is equally apparent,
however, that the steps the states have proposed offer
no assurance that they will block the carp over the short
run or, over the long run, that they will save the Great
Lakes ecosystem and the $7 billion industry that
depends on that ecosystem. We must therefore turn to
the other side of the equation: the harm that the
proposed steps would inflict on the opponents of pre-
liminary relief.
3
The states have adopted a rather insouciant attitude
about the potential harm that their proposal might inflict.
“[T]he federal government has made it clear that it is
willing to spend significant resources to reduce this
threat,” the states write, “so the cost of a few bulkheads
should not prove a serious impediment to protecting the
Great Lakes.” This tone continues throughout their
briefs, with remarks like, “While the Corps asserts that
the Coast Guard doesn’t have the funds to [dock addi-
tional ships on both sides of locks that would be closed
by the injunction], this is just a matter of money.” Of
course this dispute is in part a matter of money; but
scoffing at the defendants’ concerns about the costs of
62 No. 10-3891
relief does not aid our assessment of the expense of the
relief that the states want. It should go without saying
in these straitened times that the federal and local gov-
ernments do not have bottomless coffers. Indeed, 19
members of the plaintiff states’ delegations to Congress
recently voted against raising the federal borrowing
limit. Nor do we understand why the states take this
view when they apparently feel no obligation to
contribute to the costs of averting this crisis. When we
inquired at oral argument how the costs of the proposed
injunction should be apportioned among the parties,
the states informed us that their citizens would con-
tribute to the costs by paying federal income taxes. This
is not very helpful. Indeed, one might wonder why the
federal government and the State of Illinois should be
saddled with the entire cost of an injunction that is
aimed at a problem that has been developing for four
decades in a watershed that touches roughly half of
the states in the Union.
To make matters worse, both sides throw around large
numbers to make the case that the balance of harms
favors their position. We have already explained why
the proposed injunction is quite unlikely to prevent the
states’ forecasted $7 billion in harm. But the defendants
invent similarly extreme costs. We are told repeatedly
that almost $2 billion in cargo moves through locks in
the CAWS each year. This, however, is not the cost that
an injunction would impose on commercial shipping. If
the locks were closed, cargo would have to be loaded
from ships onto ground transportation at some point
along the journey. Estimates of the cost of off-loading
No. 10-3891 63
range from about $70 million per year (from the plain-
tiffs’ perspective) to $150 million (according to the
Corps). The intervening defendant Coalition to Save
Our Waterways, which represents various business
interests, tells us that closing the locks would cost
$4.7 billion. We find no support in the record for that
astronomical estimate. The dollar value of the harm to
either side is of course difficult to calculate, but we
need not settle on a precise number to resolve this appeal.
If the requested preliminary injunction were to issue,
we can be sure that it would impose significant costs.
First, we would have the expenses of implementing all
of the measures that the states have recommended.
In addition, funds that the defendants spend complying
with the injunction likely would be diverted from other
agency efforts to curb invasive carp. If we required
the Corps to complete its long-term study within
18 months, the Corps suggests that it would not have
time to study the problem comprehensively and that the
study might not adequately support any proposed solu-
tions. The prospect of closing the locks permanently,
installing screens on sluice gates, and placing block nets
in the CAWS increases the risk of flooding, which (to the
extent that it occurs) would impose costs throughout the
region. The states say that there are ways to avoid
those costs. The locks, for example, could be opened
at the District’s discretion during flooding. But, as we
have explained, this would be possible only if the states
agreed that bulkheads were not necessary. (The states
argue that bulkheads could be removed by a barge and
crane to permit for flood relief. Even if that were possible,
64 No. 10-3891
stationing barges at both locks would cost thousands of
dollars per day.) Screens installed over sluice gates
used during flooding could become clogged, and the
states’ suggestion that raking systems be installed to
alleviate this concern is both untested and would
require significant additional expenditures. Mean-
while, closing the locks to boat traffic would have a
tremendous impact. Police and fire services on which the
City of Chicago relies would not be able to move from the
Chicago River and other points in the CAWS to Lake
Michigan, which means that the city would have to
establish redundant emergency response fleets on either
side of the locks. The same goes for Coast Guard opera-
tions around the CAWS. Recreational and tourist vessels
would be stopped. And last but certainly not least,
closed locks would mean that all commercial shipping in
the area between the Great Lakes and the Mississippi
would have to find alternative routes.
We can stop there. This overview demonstrates that
the preliminary injunction the states have requested
would impose substantial costs, yet given the current
state of the record, we are not convinced that the pre-
liminary injunction would assure much of a reduction
in the risk of the invasive carp establishing themselves
in Lake Michigan in the near future. That the balance
of harms at this stage of the litigation favors the
defendants might be enough by itself to support a con-
clusion that preliminary relief is not warranted, even
though we have concluded that the states have demon-
strated a likelihood of success on the merits and a threat
of irreparable harm. See Hoosier Energy Rural Elec. Co-op
No. 10-3891 65
v. John Hancock Life Ins. Co., 582 F.3d 721, 725 (7th Cir.
2009) (describing the relation between the harm pre-
vented by the plaintiff’s proposed injunction and the
strength of a plaintiff’s claim for preliminary relief).
Even if one were to conclude that the harms are in equi-
poise, however, there is a final reason why preliminary
injunctive relief is not warranted. As things now stand,
the case for judicial intervention is refuted by the fact
that the competent federal and state actors are actively
pursuing an array of efforts to solve the problem of in-
vasive carp.
B
1
While American Electric Power is a case about congres-
sional displacement of federal common law, the Su-
preme Court took the opportunity to touch generally on
the relative competence of courts and expert agencies
when it comes to solving complex environmental prob-
lems. “It is altogether fitting that Congress designated
an expert agency, here, EPA, as best suited to serve as
primary regulator of greenhouse gas emissions,” the
Court wrote, explaining further:
The expert agency is surely better equipped to do the
job than individual district judges issuing ad hoc,
case-by-case injunctions. Federal judges lack the
scientific, economic, and technological resources an
agency can utilize in coping with issues of this order.
Judges may not commission scientific studies or
66 No. 10-3891
convene groups of experts for advice, or issue rules
under notice-and-comment procedures inviting
input by any interested person, or seek the counsel
of regulators in the States where the defendants are
located. Rather, judges are confined by a record com-
prising the evidence the parties present. Moreover,
federal district judges, sitting as sole adjudicators,
lack authority to render precedential decisions
binding other judges, even members of the same court.
American Electric Power, 131 S. Ct. 2539-40 (internal citation
omitted). This limitation of the judiciary is a familiar
feature of American law. See, e.g., Negusie v. Holder, 129
S. Ct. 1159, 1171 (2009) (Stevens, J., concurring in part and
dissenting in part); Kelo v. City of New London, 545 U.S. 469,
487-88 (2005); Lingle v. Chevron U.S.A., Inc., 544 U.S. 528,
544-45 (2005); Chevron, U.S.A., Inc. v. Natural Res. Def.
Council, Inc., 467 U.S. 837, 865-66 (1984); Tennessee Valley
Authority v. Hill, 437 U.S. 153, 194-95 (1978).
Our sister circuits have explored the impact of this
inherent limitation of the judicial role in cases
comparable to ours. The Second Circuit has written
that “[c]ourts traditionally have been reluctant to enjoin
as a public nuisance activities which have been con-
sidered and specifically authorized by the government.”
New England Legal Found. v. Costle, 666 F.2d 30, 33 (2d Cir.
1981). In the same vein, the Fourth Circuit recently re-
versed a lower court’s decision to enter an injunction
that would have required the TVA to implement new
emissions controls. North Carolina, ex rel. Cooper, 615
F.3d 291. The district court in that case entered an in-
No. 10-3891 67
junction after North Carolina sued the TVA for air pol-
lution based on a state common-law public nuisance
theory. The court of appeals concluded that granting
“the injunction would encourage courts to use vague
public nuisance standards to scuttle the nation’s
carefully created system for accommodating the need for
energy production and the need for clear air.” Id. at 296.
Though the case involved a more robust regulatory
scheme than the one that has been cobbled together for
the invasive carp, the court’s discussion is instructive
insofar as it relates to the problems created when courts
attempt to stop a nuisance at the same time that
agencies are working to solve the problem. An approach
that would allow the federal court and the EPA simulta-
neously to regulate a single emissions problem, said
the Fourth Circuit, would result in multiple and
perhaps contradictory decrees emanating from different
branches of government and confusion about what stan-
dards should govern air pollution. Id. at 301-04. In addi-
tion, judicial action in the face of strong agency
measures “would reorder the respective functions of
courts and agencies.” Id. at 304. Environmental problems
require the balancing of many complicated interests,
and agencies are better suited to weigh competing pro-
posals and select among solutions. Id. at 305 (“[W]e
doubt seriously that . . . a judge holding a twelve-day
bench trial could evaluate more than a mere fraction of
the information that regulatory bodies can consider.”).
None of this means that courts can no longer craft
remedies designed to abate a public nuisance. In light
of the general approach the Supreme Court took in Ameri-
68 No. 10-3891
can Electric Power, however, it does mean that the
court should not blind itself to other remedies that are
available under the law or to other measures that are
actively being pursued to solve the problem. Even if
legal displacement like that found in American Electric
Power does not exist, the practical effect of agency
actions might add up to displace as a matter of fact
any role that equity might otherwise play. Efforts of
other branches of government might be so complete
that additional action ordered by a court would risk
undermining agency efforts to abate the nuisance.
How much the equitable power of the court has been
limited by agency action will be a factual question that
turns on the quality and quantity of the agency’s (or, as
here, agencies’) efforts. This kind of institutional con-
sideration of the court’s relative ability to craft
meaningful relief fits naturally in the balance-of-harms
analysis. For if an injunction might hamper agency
efforts or can improve upon them only slightly, that is
all the more reason to conclude that the equities tilt in
favor of the defendant.
2
The record in this case leaves no doubt that federal and
state agencies, executive officials, and working groups
have mounted a tremendous effort to halt the migration
of invasive carp. As we have already mentioned, the
Aquatic Nuisance Prevention and Control Act of 1990
created the Aquatic Nuisance Species Task Force, which
includes among other agencies the National Oceanic
No. 10-3891 69
and Atmospheric Administration, the U.S. Fish and
Wildlife Service, the U.S. Geological Survey, and the
EPA. This task force coordinates invasive species issues
generally across the country. In addition, during the
fall of 2009, 21 federal, state, and local agencies and
other entities combined forces to form the Asian Carp
Regional Coordinating Committee (the ACRCC), which is
designed (as the name suggests) to track and to stop the
migration of invasive carp. See generally Asian Carp
Control, http://www.asiancarp.org/. The ACRCC counts
as members those agencies that comprise the task force,
the Corps and the District, the Coast Guard, the U.S.
Department of Transportation, the White House Council
on Environmental Quality, the Great Lakes Fishery Com-
mission, the City of Chicago, and the state departments
of natural resources of all of the plaintiff states, plus
Illinois, Indiana, and New York.
In order to stop the invasive carp, the ACRCC has
developed what it calls the “Asian Carp Control
Strategy Framework,” which is now in its third edition.
The most recent document lists over 40 collaborative
projects that the working group has designed to deal
with invasive carp; many of these initiatives are under-
way or have been completed already. As the ACRCC
describes it, the projects fall into eight categories:
(1) targeted monitoring assessment activities above
and below the electric barrier system, including en-
hanced monitoring above and below the barriers,
electrofishing, and rapid response teams;
(2) commercial harvesting and removal actions
below the electric barriers (which involves fishing
70 No. 10-3891
and removal of fish in the Lockport area, where the
CAWS connects to the Des Plaines River; creating
new markets for the fish; and investigating certifica-
tion requirements for invasive carp to be sold com-
mercially);
(3) electric barrier actions and waterway separation
measures (consisting of the construction of barriers
between various waterways so that fish cannot move
from one to the other during flooding; expedited
construction of the now-completed third electric
barrier; fish tagging to test the effectiveness of the
barriers; and separation of various watersheds
that pose risks);
(4) myriad studies on how best to separate the water-
sheds; the effectiveness of various measures; and
risk modeling;
(5) research and technology development (including
investigation of how fish move around the CAWS;
food sources for invasive carp in the lakes and how
those sources might be eliminated; the use of seismic
technology to divert or kill invasive carp; attraction
and repulsion pheromones of invasive carp; creation
of toxin screens to kill fish; study of the weaknesses
of carp to different toxins; physical barriers; reducing
carp egg viability; and new detection methods,
among other things);
(6) eDNA analysis and refinement (which involves
monitoring and sampling for eDNA in the CAWS
and increasing the effectiveness of eDNA testing);
No. 10-3891 71
(7) enforcement activities designed to prevent people
from transferring carp between bodies of water; and
(8) work on funding, including the development of
methods to pay for measures among the contributing
groups.
In addition, the ACRCC has established three working
groups: monitoring and rapid response; invasion control;
and communication and outreach.
What we have described already reflects a substantial
effort, but there is more. The Corps has been fulfilling the
marching orders that it has received from Congress. In
addition to the electric barriers and GLMRIS, which we
have discussed in detail, we have mentioned the Corps’s
study of the effectiveness of its three electric barriers for
stopping the movement of invasive carp through the
CAWS. The final version of the Efficacy Study is due later
this year, but there already have been four interim
reports (numbered in typical bureaucratic fashion as
Interim I, II, III, and IIIA), and the Corps has implemented
measures pursuant to some of these reports. Interim I
identified an area where the Des Plaines River and the
Chicago Sanitary and Ship Canal are so close together
that carp could wash between them during floods. (The
plaintiffs had argued in their complaint that this area
represented a huge problem.) The Corps has since built
a fence to stop migration between these waterways, and
that fence has already proven effective. Meanwhile,
Interim II, which is not yet completed, will set operational
parameters for the three electric barriers so that they
can most effectively deter the movement of invasive
72 No. 10-3891
species. The Corps says that even though this study is
not finished, it now operates the barriers at the maximum
safe strength. In connection with its Interim III report,
the Corps consulted a panel of experts about a number
of potential changes to its operation of the CAWS. The
report concluded that additional screens should be in-
stalled on sluice gates, and the District responded by
adding screens to two gates at O’Brien, which supple-
mented the two it had installed months earlier at the
Controlling Works. In addition, Interim III recom-
mended that the District cease using the sluice gate at
Wilmette for diversion, and it hypothesized that the
District might be able to create “atoxic zones” in the
CAWS that would be so toxic that no fish would ever be
able to swim through them. Finally, the Corps in Interim
IIIA recommended the construction of an acoustic,
air-bubble, and strobe-light curtain (more or less a disco
screen), which would be designed to frighten fish back
toward the Mississippi. The disco screen has not been
started, but the Corps represented to us at oral argument
that it intends to undertake the project at some location
downstream of the existing electric barriers.
In addition to the measures outlined in the interim
efficacy reports, the agencies continue to rely on traditional
methods to monitor and kill invasive carp, including
tracking, netting, electrofishing, and rotenone poisoning;
and, as we have discussed, they have also continued eDNA
testing throughout the CAWS. Where eDNA reveals a
potential threat, the agencies have responded with
days-long hunts for invasive carp. Continual fishing south
No. 10-3891 73
of the CAWS reduces the propagule pressure that would
otherwise push carp closer to Lake Michigan. Finally, the
Obama Administration has named an “Asian carp czar,”
who is charged with leading the administration’s effort
to stop invasive carp. Recently, the administration an-
nounced plans to install a high-intensity water cannon
that would deter fish by firing huge, underwater blasts
of water across Chicago Ship and Sanitary Canal.
It is our understanding that the defendants and the
agencies we have just discussed are actively pursuing
the measures that we have just described. In addition,
where the defendants have represented that future
steps will be taken—whether a disco screen, the water
gun, operating the electric barriers at optimal settings,
considering the possibility of block nets in the CAWS,
completing and implementing GLMRIS in phases, con-
tinuing to monitor aggressively with traditional and
eDNA techniques, or any of the other actions we have
highlighted—we have no reason at this point to assume
that this work will not be done. Whatever happens, the
plaintiff states will continue to have a seat at the table
as these and future plans are made and implemented.
We conclude that on this record, there is nothing
that any preliminary injunction from the court could
add that would protect the Great Lakes from invasive
carp while this suit is being adjudicated any better than
the elaborate measures we have just described. This
tips the balance of harms decisively in favor of the de-
fendants.
74 No. 10-3891
VI
We take very seriously the threat posed by the
invasive species of carp that have come to dominate
parts of the Mississippi River basin and now stand
at the border of one of the most precious freshwater
ecosystems in the world. Any threat to the irreplaceable
natural resources on which we all depend demands the
most diligent attention of government. As the case pro-
ceeds, the district judge should bear in mind that the
risk of harm here depends upon both the probability of
the harm and the magnitude of the problem that would
result. In the end, however, the question whether
the federal courts can offer meaningful equitable re-
lief—either preliminary or permanent—to help abate a
public nuisance in the face of agency action is factual
in nature. It depends on the actual measures that the
agencies have implemented already and those that they
have committed to put in place going forward. Our
ruling today is tied to our understanding of the
current state of play. We recognize that the facts on the
ground (or in the water) could change. The agencies
currently working hard to solve the carp problem might
find themselves unable to continue, for budgetary
reasons, because of policy changes in Washington, D.C.,
or for some other reason. If that happens, it is possible
that the balance of equities would shift. Similarly, new
evidence might come to light which would require more
drastic action, up to and including closing locks on
Lake Michigan for a period of time. If either situation
comes to pass, then the district court would have the
authority to revisit the question whether an exercise of
No. 10-3891 75
its equitable powers is warranted, taking into account
the principles we have discussed in this opinion. As
things stand now, however, preliminary relief is not
appropriate. The district court’s judgment is A FFIRMED.
9-13-11