Michigan v. US Army Corps of Engineers

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 Œ

O PINION P UBLISHED S EPTEMBER 13, 2011

Œ

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