Volume 1 of 2

FOR PUBLICATION

UNITED STATES COURT OF APPEALS

FOR THE NINTH CIRCUIT

NATURAL RESOURCES DEFENSE 

COUNCIL, INC.; THE INTERNATIONAL

FUND FOR ANIMAL WELFARE;

CETACEAN SOCIETY INTERNATIONAL;

LEAGUE FOR COASTAL PROTECTION;

OCEAN FUTURES SOCIETY; JEANMICHEL COUSTEAU,

Plaintiffs-Appellees,

CALIFORNIA COASTAL COMMISSION,

Intervenor-Appellee,

v. No. 08-55054

DONALD C. WINTER, Secretary of D.C. No. the Navy; UNITED STATES  CV-07-00335-FMC DEPARTMENT OF THE NAVY; CARLOS

M. GUTIERREZ, Secretary of the OPINION

Department of Commerce;

NATIONAL MARINE FISHERIES

SERVICES; WILLIAM HOGARTH,

Assistant Administrator for

Fisheries of the National

Oceanographic and Atmospheric

Administration; CONRAD C.

LAUTENBACHER, JR., Administrator

of the National Oceanographic and

Atmospheric Administration,

Defendants-Appellants. 

Appeal from the United States District Court

for the Central District of California

Florence Marie Cooper, District Judge, Presiding

2079
Argued and Submitted

February 27, 2008—Pasadena, California

Filed February 29, 2008

Before: Betty B. Fletcher, Dorothy W. Nelson, and

Stephen Reinhardt, Circuit Judges.

Opinion by Judge B. Fletcher

2080 NRDC v. WINTER
COUNSEL

Ronald J. Tenpas (argued), Acting Assistant Attorney General; Michael R. Eitel, Luther L. Hajek, and Allen M. Brabender, Appellate Section, U.S. Department of Justice,

Environment & Natural Resources Division, Washington,

D.C.; Craig D. Jensen and J. Page Turney, Office of General

Counsel, Department of the Navy, for the federal defendantsappellants. 

Joel R. Reynolds, Cara A. Horowitz, Stephen Zak Smith, Natural Resources Defense Council, Inc., Santa Monica, California; Richard B. Kendall (argued), Gregory A. Fayer, and Josh

B. Gordon, Irell and Manella LLP, Los Angeles, California,

for the plaintiffs-appellees. 

Edmund G. Brown, Jr., Janet Gaard, J. Matthew Rodriguez,

Jamee Jordan Patterson (argued), Office of the Attorney Gen2084 NRDC v. WINTER
eral of California, for intervenor-appellee California Coastal

Commission.

OPINION

B. FLETCHER, Circuit Judge: 

Defendants Secretary of the Navy, Department of the Navy,

Secretary of the Department of Commerce, National Marine

Fisheries Service (NMFS),1 and two Administrators of the

National Oceanographic and Atmospheric Administration

(NOAA) appeal the district court’s January 3, 2008 order, as

modified on January 10, 2008, granting a motion for a preliminary injunction and imposing certain conditions on the completion of the remaining eight of fourteen large training

exercises scheduled to be conducted by the Navy’s Third

Fleet in the waters off the coast of southern California

between February 2007 and January 2009 (the “SOCAL exercises”).2

 The motion was filed by plaintiffs Natural Resources

Defense Council, Inc., International Fund for Animal Welfare, Cetacean Society International, League for Coastal Protection, Ocean Futures Society, and Jean-Michel Cousteau

(collectively “NRDC” or “plaintiffs”), who are concerned that

the Navy’s use of high-intensity, mid-frequency active sonar

(“MFA sonar”) in the SOCAL exercises will cause serious

harm to various species of marine mammal present in the

southern California waters, and by extension, to plaintiffs

themselves. 

1The National Marine Fisheries Service has now been renamed “NOAA

Fisheries.” Because many of the documents refer to the agency by its former name, it shall be referred to as “the NMFS” throughout this opinion.

2While the district court imposed the injunction when the Navy had yet

to conduct nine training exercises, it issued a temporary partial stay of its

injunction on January 17, 2008, after which the Navy conducted its sixth

exercise. Accordingly, only eight of the fourteen scheduled exercises have

not yet been conducted. 

NRDC v. WINTER 2085
In granting NRDC’s motion for a preliminary injunction,

the district court found that NRDC had demonstrated probable

success on the merits of its claim that the Navy violated the

National Environmental Policy Act (“NEPA”), 42 U.S.C.

§ 4321 et seq., by failing to prepare an Environmental Impact

Statement (“EIS”). The district court also found that NRDC

had demonstrated probable success on the merits of its claim

that the Navy violated the Coastal Zone Management Act

(“CZMA”), 16 U.S.C. § 1451 et seq., by submitting a consistency determination to the California Coastal Commission

(“CCC”) that did not take into account the planned use of

MFA sonar and by failing to adopt the mitigation measures

the CCC determined were necessary for the SOCAL exercises

to be consistent with the California Coastal Management Program (“CCMP”). 

On January 15, 2008, the Council on Environmental Quality (“CEQ”) purported to approve “alternative arrangements,”

pursuant to 40 C.F.R. § 1506.11, that would permit the Navy

to continue its exercise without first completing an EIS. On

the same day, President George W. Bush, pursuant to 16

U.S.C. § 1456(c)(1)(B), exempted from the requirements of

the CZMA the Navy’s use of MFA sonar in the SOCAL exercises. 

On February 4, 2008, the district court upheld its injunction

on the basis of plaintiffs’ NEPA claim, concluding CEQ’s

action was invalid and therefore not entitled to deference. The

district court also expressed concerns about the constitutionality of the President’s CZMA exemption on the ground that it

appeared to amount to an executive revision of a judicial decision and thus violated the principle, recognized in Hayburn’s

Case, 2 U.S. (2 Dall.) 408 (1792), that Congress cannot vest

review of the decisions of Article III courts in officials of the

Executive Branch. However, the court declined to decide the

constitutionality of the CZMA exemption because it concluded the preliminary injunction was firmly supported on

2086 NRDC v. WINTER
NEPA grounds.3

 The district court also found that plaintiffs

had demonstrated a possibility of irreparable harm and that

the balance of hardships tipped in plaintiffs’ favor. Natural

Res. Def. Council v. Winter, ___ F.Supp. 2d ___, 2008 WL

314192 (C.D. Cal. Feb. 4, 2008) (“Feb. 4, 2008 Dist. Ct.

Order”). 

For the reasons stated below, we uphold the district court’s

preliminary injunction. 

I. Procedural History

Plaintiffs commenced this action on March 22, 2007. On

August 7, 2007, the district court granted in part NRDC’s

motion for a preliminary injunction and enjoined the Navy

from conducting the then remaining eleven SOCAL exercises.4

After appealing the district court’s preliminary injunction

order,5 the Navy filed an emergency motion with this court for

a stay of the order while its appeal was pending. On August

31, 2007, a divided motions panel granted the Navy’s motion

on the grounds that the district court had failed to consider the

“public interest” in having a trained and effective Navy and

had failed to explain why an unconditional injunction on the

SOCAL exercises, rather than an injunction conditioning the

conduct of those exercises on the adoption of additional mitigation measures, was appropriate. NRDC v. Winter, 502 F.3d

859 (9th Cir. 2007). 

3Because the district court did not rule on the likelihood of success of

plaintiffs’ CZMA claim in light of the President’s exemption, we decline

to reach that issue. 

4The district court granted NRDC’s motion only in part because it found

that NRDC had not demonstrated probable success on the merits of its

additional claim that the NMFS and the other non-Navy defendants had

failed to prepare an adequate Biological Opinion and Incidental Take

Statement in violation of the Endangered Species Act and the Administrative Procedure Act. NRDC has not appealed that portion of the district

court’s ruling. 

5The CCC has intervened as appellee in this action. 

NRDC v. WINTER 2087
On November 13, 2007, after hearing oral argument, we

filed an order concluding that NRDC had met the necessary

burden of proof to demonstrate that some form of preliminary

injunctive relief was appropriate. Accordingly, we vacated the

stay of the preliminary injunction order effective upon the

Navy’s completion of its fifth SOCAL exercise, which was in

progress at the time of oral argument. However, we also concluded that an injunction conditioning continuation of the

exercises on the Navy’s adoption of narrowly tailored mitigation measures would be more appropriate than a total injunction. Accordingly, we remanded the case for the district court

to enter a modified preliminary injunction containing appropriate mitigating measures. NRDC v. Winter, 508 F.3d 885

(9th Cir. 2007). 

On January 3, 2008, the district court, after having received

briefing from the parties and having toured the destroyer USS

Milius at the naval base in San Diego, California, to improve

its understanding of the Navy’s sonar training procedures and

the feasibility of the parties’ proposed mitigation measures,

issued a new preliminary injunction that allowed the Navy to

conduct the remaining SOCAL exercises provided that it

employ certain measures intended to mitigate the impact of

the Navy’s use of MFA sonar on the environment. On January

9, 2008, the Navy applied for a stay pending appeal and

requested relief from the district court by January 14, 2008.

On January 10, 2008, in response to arguments raised in the

Navy’s stay application, the district court modified the preliminary injunction by narrowing the mitigation measures

contained in the January 3, 2008 order. The Navy filed a

notice of appeal the following day. The district court denied

the Navy’s stay application on January 14, 2008. 

On the evening of January 15, 2008, the Navy filed an

emergency motion with this court requesting vacatur of the

preliminary injunction or, alternatively, a partial stay of the

preliminary injunction pending a decision on its appeal by our

2088 NRDC v. WINTER
court. The Navy’s motion was based in part on two developments that occurred on the same day that the motion was

filed. First, the President of the United States, pursuant to 16

U.S.C. § 1456(c)(1)(B), exempted from the provisions of the

CZMA the Navy’s use of MFA sonar during the SOCAL

exercises, finding that such use of MFA sonar is “essential to

national security” and in the “paramount interest of the United

States.” Second, the CEQ, finding “emergency circumstances,” purported to approve “alternative arrangements” to

accommodate those emergency circumstances, pursuant to 40

C.F.R. § 1506.11. It permitted the Navy to follow the prescribed arrangements to continue its exercises pending completion of the Navy’s EIS. The Navy subsequently adopted

the alternative arrangements and determined that it would

comply with them. See Decision Memorandum Accepting

Alternative Arrangements for the U.S. Navy’s Southern California Operating Area Composite Training Unit Exercises and

Joint Task Force Exercises Scheduled To Occur Between

Today and January 2009, 73 Fed. Reg. 4189 (Jan. 24, 2008).

On January 16, 2008, we remanded the matter to the district

court to consider in the first instance the effect, if any, of

these developments on its preliminary injunction order. On

January 17, 2008, the district court issued a temporary partial

stay of its preliminary injunction order pending the court’s

consideration of the Navy’s ex parte application to vacate the

preliminary injunction. The Navy subsequently conducted its

sixth SOCAL exercise. 

On February 4, 2008, following briefing by the parties and

oral argument, the district court denied the Navy’s application

to vacate the preliminary injunction and lifted the temporary

partial stay. In its published order, the district court held in

relevant part that CEQ’s approval of “alternative arrangements” was invalid because there are no “emergency circumstances” within the meaning of 40 C.F.R. § 1506.11. Feb. 4,

2008 Dist. Ct. Order at 13-25. Thus, the district court left in

NRDC v. WINTER 2089
place the original preliminary injunction. The Navy filed a

notice of appeal two days later. 

On February 8, 2008, we issued a sua sponte order expediting the appeal of the district court’s order imposing the preliminary injunction. On February 15, 2008, the Navy filed an

emergency motion for a partial stay of the preliminary injunction pending our consideration of the appeal on the ground

that the injunction would interfere with the Navy’s conduct of

two exercises in March, 2008. On February 19, 2008, we

denied the Navy’s motion for a partial stay in light of our

order expediting the appeal, which set oral argument for

Wednesday, February 27, 2008. We now affirm the district

court’s order imposing the preliminary injunction. 

II. Factual Background

A. The SOCAL Exercises and the Effect of MFA

Sonar on Marine Mammals

The scheduled SOCAL exercises consist of seven Composite Training Unit Exercises (“COMPTUEX”), which last three

to four weeks each, and seven Joint Tactical Force Exercises

(“JTFEX”), which last approximately ten days each. The

exercises, which involve the use of multiple surface ships, aircraft and submarines, are part of the “integrated” training

phase of the Navy’s Fleet Response Training Plan, in which

individual naval units — ships, submarines and aviation

squadrons — learn and demonstrate skills as members of a

strike group.6 Declaration of Captain Martin N. May (“May

6The Navy employs two types of strike groups. A carrier strike group

generally consists of an aircraft carrier and five surface combatant ships.

May decl. ¶ 5. An expeditionary strike group includes surface combatant

ships and an amphibious ready group. Id. 

A strike group starts developing skill sets at the individual ship, submarine, or aviation squadron level by conducting unit-level training. Id. ¶ 6.

As skill levels increase, units coordinate training with other units. Id. Prior

2090 NRDC v. WINTER
decl.) ¶ 6. In a COMPTUEX exercise a strike group must

demonstrate that it is capable of operating in a “complicated

threat-based scenario environment that simulates real world

situations.” Id. In a JTFEX exercise, which follows the

COMPTUEX exercise and typically includes other Department of Defense services and Allied Forces, the focus is on

“mission planning and strategy and on the orchestration of

integrated maneuvers, communication and coordination.” Id.

¶ 7. Upon completion of the integrated training phase the

Fleet Commander is able to certify that a strike group is ready

for deployment. Id. 

According to the Navy, the ability to execute antisubmarine warfare (“ASW”) is critical to a Commander’s certification of a strike group. Id. Improving ASW is the Pacific

Fleet’s top “war-fighting” priority because of the proliferation

of extremely quiet diesel electric submarines throughout the

world.7Id. ¶ 11; Dec. 14, 2007 Declaration of Rear Admiral

John M. Bird (“Bird. Decl”) ¶ 16. In turn, an important part

of ASW is the use of active sonar, a technology which the

Navy deems absolutely necessary to detect today’s extremely

quiet submarines. The type of active sonar, the use of which

to commencing the “integrated” phase of the Navy’s training plan, the

individual units comprising a strike group must be trained and attain proficiency in the “basic” phase of the training plan. Id. ¶ 25. During the “integrated” training phase, an individual unit learns and demonstrates skills as

a team member of the strike group. Following completion of the “integrated” phase, strike groups enter the “sustainment” phase of the training plan.

Id. This phase continues through the strike group’s scheduled deployment

and post-deployment periods and ends with the commencement of the

“maintenance” phase, during which the ships comprising the strike group

undergo maintenance and modernization. Id. ¶¶ 24, 25. 

7We note that neither quiet submarines, nor the use of active sonar to

detect them, are new technologies. According to the Navy’s Environmental Assessment (“EA”), active sonar was used effectively against German

U-boats during World War II, and during the Cold War technological

developments in active sonar were “critical” for tracking sophisticated

Soviet submarines. 

NRDC v. WINTER 2091
NRDC challenges, is mid frequency active sonar; other categories of active sonar are low-frequency active sonar and

high-frequency active sonar.8

Active sonar involves a vessel or other sonar source emitting a loud noise underwater and then listening for whether

the noise comes back to the source, indicating that the noise

may have bounced off the hull of a previously undetected submarine. According to the Navy, active sonar has two important advantages over passive sonar, which merely involves

listening for noise made by submarines themselves: active

sonar gives both the bearing and the distance of the target

submarine, while passive sonar gives only the bearing;9 and

active sonar allows the Navy to target submarines that emit

sound at levels below those of the surrounding marine environment. Bird decl. ¶ 9. Accordingly, the Navy has concluded

that in certain environments, including shallow coastal waters

where ambient noise levels are high, MFA sonar allows better

detection of quiet submarines than passive sonar. May decl.

¶¶ 9, 14. 

According to the Navy, personnel using MFA sonar must

train with it regularly, under realistic conditions, and in a variety of situations. May decl. ¶ 10. The Navy therefore trains

with MFA sonar in the ASW exercises that constitute an

important component of the SOCAL exercises.

The SOCAL exercises are conducted in the Navy’s training

ranges off the coast of southern California (“the Southern California Operating Area”). This area is located in biologically

8According to the Navy, low-frequency active sonar is transmitted at

frequencies between 0.1 kHz and 1.0 kHz; mid-frequency active sonar at

frequencies between 1.0 kHz and 10.0 kHz; and high-frequency active

sonar at frequencies greater than 10.0 kHz. Bird decl. ¶ 12; May decl. ¶ 9.

9Active sonar allows a calculation of the distance of a target submarine

by considering the speed at which the sonar sound moves through water

and the time it takes for emitted sonar sound to travel to the target and

back. Bird decl. ¶ 12. 

2092 NRDC v. WINTER
diverse waters. At least thirty-seven species of marine mammals are found there, with the most common being various

species of dolphin and whale, as well as the California sea

lion. Nine of those species are listed as threatened or endangered under the Endangered Species Act (“ESA”), 16 U.S.C.

§ 1531 et seq.: the blue whale, fin whale, humpback whale,

Northern Pacific right whale, sei whale, sperm whale, sea

otter, Stellar sea lion, and Guadalupe fur seal. In addition, up

to eight species of beaked whale are found in the Southern

California Operating Area. A study submitted by NRDC classifies the California coastal waters as a “key area” for beaked

whales because over 25% of all beaked whale species are

found there.10

The Navy acknowledges in its EA that MFA sonar may

affect both the physiology and behavior of marine mammals.

Exposure to “very high” acoustic energy levels may impair

the functioning of marine mammals’ visual system, vestibular

system and internal organs, and may cause injury to their

lungs and intestines. However, the primary physiological

effects of MFA sonar are on marine mammals’ auditory system: very high sound levels may rupture the eardrum or damage small bones in the middle ear, but even exposure to lower

levels of sound may cause permanent or temporary hearing

loss. 

Several studies suggest that active sonar may also cause a

form of decompression sickness (or the “bends”) in marine

mammals by inducing growth of gas bubbles in their blood

stream or tissues, potentially leading to fatal hemorrhaging,

lesions and emboli in the organs. However, the Navy disputes

the conclusions of these studies and it has submitted a decla10According to the study, the “key area” in southern California comprises the California shelf margins, which the study defines as the area

west of the Californian coast up until the 125.0 degree longitude. Navy

maps in the record show that the Southern California Operating Area falls

largely within this area. 

NRDC v. WINTER 2093
ration by an expert on marine mammal auditory systems stating that decompression sickness requires super-saturation of

tissue with gas and that such super-saturation has not been

shown to occur in marine mammals. See Declaration of Dr.

Darlene R. Ketten (“Ketten decl.”) ¶¶ 12-16. 

The Navy also acknowledges that the use of MFA sonar

may overtly disrupt the normal behavior of marine mammals

even if it does not affect their physiology. While the Navy

acknowledges that active sonar may cause behavioral

responses such as attempting to avoid the site of sound exposure, swimming erratically, sluggish behavior, tail slapping,

“jaw popping,” and aggressive behavior, those responses were

observed in studies using trained animals held in captivity.11

NOAA concluded in 2006 that studies of marine mammals in

the wild “strongly suggest” that the use of sonar at levels

lower than those found to produce behavioral effects in the

tests of captive animals can result in “profound” behavioral

alterations, including changes in feeding, diving, and social

behavior. In a February 9, 2007 Biological Opinion concerning the SOCAL exercises,12 the NMFS found that acoustic

exposures can impair marine mammals’ foraging ability and

their ability to detect predators or communicate. The NMFS

cited studies finding that noise has caused whales to move

away from their feeding and mating grounds and migration

routes, and to change their calls. 

11These behavioral responses were observed in a study to which the EA

cites for the effects of MFA sonar on marine mammals. See J.J. Finneran

and C.E. Schlundt, Effects of Intense Pure Tones on the Behavior of

Trained Odontocetes, Space and Naval Warfare Systems Center, San

Diego, Technical Document (September 2004). 

12The NMFS issued the Biological Opinion pursuant to section 7(a)(2)

of the Endangered Species Act (“ESA”), 16 U.S.C. § 1536(a)(2), which

concluded that while the SOCAL exercises might “adversely affect” certain threatened and endangered species, the exercises were not “likely to

jeopardize the [species’] continued existence.” The NMFS also issued an

Incidental Take Statement under which harm done to animals of the

threatened or endangered species would be excused under the ESA as incidental. 

2094 NRDC v. WINTER
As the record demonstrates, substantial evidence suggests

that beaked whales are particularly vulnerable to MFA sonar.

While it is not settled what causes this vulnerability,13 it is

clear that use of MFA sonar may lead to the stranding of

beaked whales. A 2004 Navy-sponsored study concluded that

“the evidence of sonar causation is . . . completely convincing

and that therefore there is a serious issue of how best to avoid/

minimize future beaching events.” Likewise, the Standing

Working Group on Environmental Concerns of the International Whaling Commission’s Scientific Committee concluded in 2004 that “[t]he weight of accumulated evidence

now associates mid-frequency, military sonar with atypical

beaked whale mass strandings,” and found that “[t]his evidence is very convincing and appears overwhelming.” 

A 2006 study cited as possible explanations for the association between MFA sonar and strandings of beaked whales that

(1) beaked whales may swim into shallow waters to avoid the

sonar sound and strand if they are unable to navigate back to

deeper waters, and (2) that behavioral responses to sonar may

lead to tissue damage that in turn leads to stranding. The study

explains that while a stranding need not be fatal, stranded

marine mammals have died from cardiovascular collapse due

to hyperthermia or from the stress associated with the stranding. Several mass strandings of marine mammals—mostly,

though not exclusively, beaked whales—have been associated

with the use of active sonar. Another 2006 study describes a

stranding of twelve beaked whales in Greece in 1996, a

stranding of seventeen marine mammals (including fourteen

beaked whales) in the Bahamas in 2000, and a stranding of

13A 2004 Navy-sponsored study investigated several possible explanations for beaked whales’ vulnerability to MFA sonar, including that

beaked whales have a specialized anatomy, possibly due to their deep diving, which renders them especially sensitive to sound, and that beaked

whales are “especially skittish” such that loud, reverberant acoustic fields

cause “uncontrolled attempts to escape.” The study concluded that the latter explanation was the most likely to be correct, but that this conclusion

could change “as more research is done on this problem.” 

NRDC v. WINTER 2095
fourteen beaked whales in the Canary Islands in 2002,14 all of

which occurred at the same time and place as the naval use

of MFA sonar. The study also recounts a stranding of three

beaked whales in the Madeira Islands in 2000, which coincided with NATO’s conduct of naval exercises,15 as well as a

stranding of two beaked whales in the Gulf of California,

Mexico, in 2002, which coincided with the conduct of seismic

surveys involving, among other acoustic sources, a multibeam, high-frequency sonar. In addition, a 2006 report by the

NMFS recounts that 150 to 200 melon-head whales stranded

in a Hawaiian bay in 2004, at the same time and place as the

Navy’s use of active sonar as part of its biennial Rim of the

Pacific (RIMPAC) exercise.16

Necropsies of the dead whales involved in the Bahamas,

Canary Islands and Madeira Islands strandings revealed hemorrhages in and around the ears, in the cranial spaces, and in

other parts of the body such as the jaw fat, lungs and kidneys.

In a joint report, the Navy and NOAA concluded that the injuries to the whales that stranded in the Bahamas constituted

“some sort of acoustic or impulse trauma,” and that the

Navy’s use of MFA sonar was the “most plausible” source of

that trauma. The International Whaling Commission agreed

14Notably, the study states that after the stranding in the Canary Islands,

local researchers examined past stranding records and found reports of

eight other strandings of beaked whales in the Canaries since 1985, at least

five of which coincided with naval activities offshore. 

15According to the study, NATO has been unwilling to provide information on its sonar activity during the Madeira Island exercises. 

16The RIMPAC exercises have been conducted biennially since 1968 in

the “Hawaiian operating area” and are intended to enhance the communication and coordination between Pacific Rim armed forces “as a means of

promoting stability in the region to the benefit of all participating nations.”

Bird decl. ¶ 34. Unlike the JTFEX and COMPTUEX exercises, the RIMPAC exercises are not part of the “integrated” phase of the Fleet Response

Training Plan; they are focused on command and control among the

nations involved, and not focused on certifying strike groups for deployment. Id. However, like the JTFEX and COMPTUEX exercises, the RIMPAC exercises include ASW training that involves the use of MFA sonar.

2096 NRDC v. WINTER
that the hemorrhages in the inner ears and cranial spaces were

consistent with “direct acoustic effects.” 

According to a biologist on whose declaration NRDC

relies, the use of MFA sonar in the Bahamas may also have

had a serious effect on the local population of beaked whales.

See Declaration of Dr. Hal Whitehead. The biologist cites a

study showing that no Cuvier’s beaked whales were sighted

for twenty months following the stranding in the Bahamas,

despite an increased survey effort. Id. ¶ 8. He also cited

studies showing that of the Cuvier’s beaked whales that had

been photo-identified over a nine-year period, only a few have

been sighted since the stranding in 2000. Id. 

With respect to the stranding of the melon-head whales in

Hawaii, the NMFS issued a report concluding that “[w]hile

causation of this stranding event may never be unequivocally

determined, we consider the active sonar transmissions . . . a

plausible, if not likely, contributing factor in what may have

been a confluence of events.” 

Undoubtedly, many training exercises involving the use of

active sonar occur around the world without marine mammal

strandings being observed or reported. However, a declaration

by a NOAA scientist submitted by the Navy acknowledges

that it is generally poorly understood in which combinations

of physical and biological circumstances such strandings are

likely to occur. Declaration of Brandon L. Southall ¶ 19. The

declaration also acknowledges that whether marine mammal

strandings are observed depends on the extent to which people are looking for them. Id.

B. The Navy’s EA and the Predicted Harm to Marine

Mammals in the Southern California Waters

In February 2007, the Navy issued an Environmental

Assessment (“EA”) for the SOCAL exercises pursuant to

NEPA. See 40 C.F.R. § 1501.3. The EA set forth the Navy’s

NRDC v. WINTER 2097
estimate of how much harm the use of MFA sonar would

inflict on marine mammals, classifying the harm as either

“Level A harassment” or “Level B harassment.” 

Level A harassment is an act that physically injures the

marine mammal. Level A harassment refers to an exposure to

MFA sonar that “injures or has the significant potential to

injure a marine mammal or marine mammal stock in the

wild.” Injury is defined as any destruction or loss of any biological tissues, and includes permanent hearing loss. 

Level B harassment is an act that disrupts the behavior of

a marine mammal. Level B harassment refers to an exposure

to MFA sonar that “disturbs or is likely to disturb a marine

mammal or marine mammal stock by causing disruption of

natural behavioral patterns including, but not limited to,

migration, surfacing, nursing, feeding, or sheltering to a point

where such behaviors are abandoned or significantly altered.”

Notably, Level B harassment may also, though it need not,

include temporary hearing loss. 

The behavioral effects that result from Level B harassment

may have severe consequences. According to the Biological

Opinion of the NMFS, acoustic exposures can result in the

death of a marine mammal by impairing its foraging or its

ability to detect predators or communicate by increasing stress

or by disrupting important physiological events. 

In its EA, the Navy classified predicted sonar exposures as

either Level A harassments or Level B harassments based on

the sound intensity to which a marine mammal would be

exposed. For cetaceans—which include whales and dolphins

and which are the focus of NRDC’s challenge to the SOCAL

exercises—the Navy applied the following “impact thresholds”: it classified as Level A harassments exposures to sonar

levels of 215 decibels (dB) or greater, as Level B harassments

including temporary hearing loss exposures to sonar levels

between 195 dB and 215 dB, and as Level B harassments not

2098 NRDC v. WINTER
including temporary hearing loss exposures to sonar levels

between 173 dB and 195 dB.17

Significantly, the Navy acknowledged in the EA that it

does not know whether the above impact thresholds apply to

beaked whales. Recognizing the recent beaked whale strandings and the fact that the exact causes of those strandings are

unknown, the Navy concluded that “separate, meaningful

impact thresholds cannot be derived specifically for beaked

whales.” Put simply, the Navy did not know whether exposure of a beaked whale to an acoustic energy of less than 215

dB might nevertheless cause permanent injury to the whale.

Accordingly, the Navy took a “conservative approach” and

counted all predicted Level B exposures of beaked whales as

non-lethal Level A exposures. Thus, the Navy treated every

predicted exposure of a beaked whale to a sonar level of 173

dB or greater as causing physical injury including permanent

hearing loss. 

In its EA, the Navy estimated that over the course of the

SOCAL exercises, the use of MFA sonar would result in 564

instances of Level A harassment to marine mammals, 548 of

which would be to beaked whales.18 Specifically, the follow17The EA expressed the impact thresholds in terms of “energy flux density level,” which is a measure of the flow of sound energy through an

area, or, more formally, the time integral of the squared pressure divided

by the impedance. Energy flux density is expressed in units of decibels

referenced to the pressure and duration of the sound, e.g., 215 dB re 1 μPa2

-s. For convenience, we express the impact thresholds, and exposures to

MFA sonar generally, only in units of decibels. 

18The statements in the EA that “[t]he modeling efforts and harassment

analysis for mid-frequency active sonar estimate that no Level A harassment” of beaked whales will occur is not to the contrary. As explained

above, the Navy acknowledged in the EA that it did not know whether the

impact thresholds it established for cetaceans generally also applied to

beaked whales. Accordingly, the Navy decided that although its harassment model using those impact thresholds did not predict any Level A

harassments to beaked whales, it would nevertheless treat all predicted

Level B harassments to beaked whales as Level A harassments. 

NRDC v. WINTER 2099
ing species would be subjected to Level A harassments:

Cuvier’s beaked whales in 436 instances; Ziphiid beaked

whales in 104 instances; common dolphins in 16 instances;

and Baird’s beaked whales in 8 instances.19

The Navy also estimated that the use of MFA sonar would

result in 8,160 exposures to Level B harassment with temporary hearing loss and 161,368 exposures to Level B harassment without hearing loss. Eight marine mammal species,

including one endangered species, would be exposed to over

1,000 incidents of Level B harassment: 145,444 exposures to

common dolphins; 6,460 exposures to Northern Pacific right

whale dolphins; 4,292 exposures to Risso’s dolphins; 4,100

exposures to Pacific white-sided dolphins, 3,252 exposures to

striped dolphins; 1,830 exposures to pygmy sperm whales

(endangered); 1,094 exposures to Pantropical spotted dolphins; and 1,092 exposures to bottlenose dolphins. 

In light of the harm that marine mammals are expected to

suffer as a result of the SOCAL exercises, plaintiffs contend

that they and their members living in southern California will

be harmed. For example, plaintiff Jean-Michel Cousteau

alleges that as an environmental enthusiast and film-maker his

ability to enjoy and educate others about the marine environment in southern California will be impaired if the harmful

effects of MFA sonar on marine mammals are not sufficiently

mitigated. Other plaintiffs make similar allegations.

The Navy stated in the EA that it “assumed” that its methodology for estimating harm overestimated the effects of

MFA sonar on marine mammals, citing the lack of observed

effects during several past major exercises. However, the EA

also maintained that the methodology used was based on the

19These figures appear in the EA’s Appendix A; the slightly different

figures cited by the parties and the district court appear to be incorrect

because they fail to account for 98 instances of Level A harassment to

Ziphiid whales.

2100 NRDC v. WINTER
“best available science,” and it provided no indication of the

extent to which its methodology overestimated the effects of

MFA sonar. In fact, there is at least some evidence that the

Navy’s methodology may have underestimated the effects of

MFA sonar on marine mammals. NRDC has submitted declarations of several scientists who cite evidence that extraordinary behavior in marine mammals, including stranding by

beaked whales, may be caused by acoustic energy levels

below the Navy’s bottom impact threshold of 173 dB. See

Declaration of Dr. David E. Bain ¶¶ 6-11; Declaration of Dr.

Edward C.M. Parsons ¶ 4; Declaration of Dr. Linda Weilgart

(“Weilgart decl.”) ¶ 9. 

While NRDC has presented no evidence that marine mammals have actually been harmed by the Navy’s use of MFA

sonar in the Southern California Operating Area over the past

forty years,20 the record indicates that because harm to marine

mammals is difficult to detect, except in cases of stranding,

marine mammals may nonetheless be harmed by the Navy’s

use of MFA sonar in the Southern California Operating Area.

In the Navy’s January 2007 “after action report” following

the completion of the first three SOCAL exercises, the Navy

acknowledged that “it is difficult to assess the potential expo20The “after action reports” compiled by the Navy following completion

of COMPTUEX and JTFEX exercises in the Southern California Operating Area do catalogue a number of marine mammal deaths. For example,

the Navy’s June 2007 “after action report” following the first three

SOCAL exercises notes that during one of the exercises the Navy

observed a floating, badly decomposed whale carcass, and that during two

of the exercises it observed floating pinniped and dolphin carcasses. The

report does not disclose whether necropsies were performed on the carcasses and it does not discuss whether the deaths might be related to the

use of MFA sonar. Instead, the report proffers only the tentative explanation that “circumstantial evidence” of a link between “potential” algal

toxin in California ocean waters and increased marine mammal mortality

“is not unexpected” and “may” have “contributed” to the fact that pinniped and dolphin carcasses were observed. June 28, 2007 COMPTUEX/

JTFEX Combined After Action Report at 13-14. 

NRDC v. WINTER 2101
sure to sonar for species not observed.” Indeed, the “after

action reports” for the last eight COMPTUEX and JTFEX

exercises in the Southern California Operating Area reveal

that in less than 15% of the instances in which marine mammals were observed, MFA sonar was in fact being used.21

Thus, the Navy’s reports show that relatively few marine

mammals have been observed while MFA sonar was being

used. 

Beaked whales are particularly difficult to observe. According to a 2004 Navy-sponsored report, “[t]heir very low

broaching profile and the limited time they spend at the surface have conspired to make them resistant to easy surveying.” The report notes that beaked whales are “very deep

divers” and spend an estimated 80% of their time at considerable depths. According to the EA, Cuvier’s and Mesoplodont

beaked whales make dives of up to 87 minutes.22 An international workshop on beaked whales organized by the U.S.

Marine Mammal Commission noted that only 1 in 50 beaked

whales would be detected in naval mitigation surveys using

shipboard visual observation, even assuming ideal observation conditions. 

Correspondingly, injuries to beaked whales are also difficult to observe. In a January 2007 memorandum, the NMFS

concluded that “injuries or mortalities . . . would rarely be

documented, due to the remote nature of many [naval activities] and the low probability that an injured or dead beaked

whale would strand.” While the parties have presented conflicting declarations on the issue whether whale carcasses

resurface for some time after they initially sink, compare

21The data in the “after action reports” for the eight COMPTUEX and

JTFEX exercises in the Southern California Operating Area show that of

345 instances of marine mammal sighting, MFA sonar was being used

only in 51 instances, or 14.8% of the time. 

22The EA provides no information on the length of the dives of Baird’s

and Ziphiid beaked whales. 

2102 NRDC v. WINTER
Weilgart decl. ¶ 7 with Ketten decl. ¶ 17, the likelihood that

a whale carcass would be detected if it does not strand logically depends on how well the waters are searched for such

carcasses. A 2007 study by NMFS researchers suggests that

the likelihood of detecting dead beaked whales is low, as it

concluded that, given current biological survey efforts, in

90% of beaked whale stocks a decline in population of 50%

over a 15-year period would go undetected as a decline at all.

Non-fatal injuries not leading to stranding would be even

more difficult to detect because no beaked whale carcass

would surface. 

Moreover, it is not clear from the record whether in the past

forty years the waters of southern California have been

exposed to MFA sonar at the same power level and frequency

and for the same duration as they are now. First, the Navy has

provided no information about the frequency with which exercises involving the use of MFA sonar were conducted prior to

1992. 

Second, while the Navy states that “Navy data going back

to 1992 shows that the number of yearly exercises in the last

15 years and amount of [MFA sonar] use in SOCAL waters

was greater in the past than it is now, showing a slight reduction trend,” Bird decl. ¶ 18, that statement is too vague to

allow conclusions to be drawn from it. The statement says

nothing about the type of exercises or their duration over the

years, and it does not make clear whether “in SOCAL waters”

refers only to sonar use or also to the number of yearly exercises. Further, the statement does not specify whether

“amount of [MFA sonar] use” refers to sonar use in each

exercise or to total sonar use in a year, nor does it make clear

whether that phrase refers to the number of times sonar was

employed or to the aggregate duration of sonar transmission.

The Navy produces no data in the record to clarify its statement. 

Third, while the EA states that an average of seven JTFEX

or COMPTUEX exercises are conducted each year, which is

NRDC v. WINTER 2103
consistent with fourteen SOCAL exercises to be conducted

over two years, the EA does not state the starting date after

which that average has been maintained. 

Fourth, while the Navy points out that its currently-used

SQS-53 sonar system transmits sonar at the same power

levels and frequencies as the SQS-26 system that the Navy

used in earlier years, it acknowledges that in a new class of

destroyers the SQS-53 system has replaced the SQS-56 system. Bird. decl. ¶ 18. As the Biological Opinion of the NMFS

makes clear, the SQS-56 system transmits MFA sonar at a

lower power level and at different frequencies than the SQS53 system.23 Thus, the record suggests that with the new class

of destroyers the average MFA sonar transmission may have

increased in power level and changed in frequency. The Navy

does not cite evidence to the contrary. 

Finally, we can draw no conclusion from the statement in

the EA that “output from active sonar systems used in [the

Southern California Operating Area] and throughout the Navy

has remained largely the same for the past 30 years.” The EA

does not explain whether “output” refers to frequency, sound

intensity level, amount of time used during an exercise, or

amount of time used per year.24 Even assuming the statement

23Moreover, the NMFS’ Biological Opinion states that two lowfrequency sonar systems are likely to be employed in the SOCAL exercises, but it does not state in what proportion they have been used in the

past or will be used now. The fact that one of those systems has the same

acoustic capabilities as, but improved processing capabilities over, the

other system—a fact to which the Navy refers in its November 13, 2007

letter to the court—is irrelevant. 

24The same lack of clarity afflicts the statement in a Navy declaration

that the Navy’s training activities involving sonar during World War II

“were similar in nature and intensity to those currently analyzed in the

[EA for the SOCAL exercises].” Declaration of Conrad Erkelens ¶ 16. The

statement does not make clear whether “intensity” refers generally to the

frequency or size of the exercises or more specifically to the length of time

during which sonar was used. Even if it refers to the latter, it appears to

refer to the use of sonar per training activity, not per year. 

2104 NRDC v. WINTER
refers to the use of the sonar systems during an exercise or

during the year, it is unclear whether it refers to total use in

the Southern California Operating Area or rather to total use

by the Navy in all its training areas combined. 

In any event, the Navy’s estimate that its use of MFA sonar

in the SOCAL exercises will expose marine mammals to 564

instances of Level A harassment and nearly 170,000 instances

of Level B harassment clearly indicates that at least some substantial harm will likely occur in the Southern California

Operating Area. 

C. The Mitigation Measures Employed by the Navy

and Those Imposed by the District Court

While the Navy adopted a number of mitigation measures

intended to reduce the harm caused by the use of MFA sonar

in the SOCAL exercises, the district court concluded that

those measures were inadequate both to cure the Navy’s

likely NEPA violation and to avoid the possibility of irreparable harm to NRDC. Accordingly, following our November

13, 2007 remand order, the district court established additional, narrowly-tailored mitigation measures which the Navy

would have to employ during the remaining SOCAL exercises. To place these mitigation measures in context, we

explain what mitigation measures the Navy has previously

employed and is currently employing in the SOCAL exercises. 

In June 2006, shortly before the Navy was to conduct that

year’s “Rim of the Pacific” exercise off the coast of Hawaii

(the “2006 RIMPAC exercise”), plaintiffs sued the Navy and

the same co-defendants here,25 seeking to enjoin the Navy

from using MFA sonar in that exercise. Following the district

court’s grant of NRDC’s motion for a temporary restraining

25Only the League for Coastal Protection was not a plaintiff in the 2006

action. 

NRDC v. WINTER 2105
order, the parties entered into a settlement agreement that

allowed the Navy to use MFA sonar in the 2006 RIMPAC

exercise but only if it employed certain mitigation measures

in addition to those already imposed by the NMFS in its June

27, 2006 Incidental Harassment Authorization and by the

Department of Defense in its June 30, 2006 National Defense

Exemption (“NDE I”).26

The mitigation measures the Navy adopted for the 2006

RIMPAC exercise include operating MFA sonar at the lowest

practicable level not to exceed 235 dB except for short periods to meet tactical training objectives, and using at least one

lookout dedicated to the detection of marine mammals, as

well as three non-dedicated lookouts, on each ship operating

MFA sonar and requiring them to report sightings of marine

mammals. 

The following mitigation measures employed during the

2006 RIMPAC exercise are of particular importance here: 

• The designation of “safety zones” in which: 

- the MFA sonar level is reduced by 6 dB

if a marine mammal is detected within

1,000 meters of the sonar dome (located

in the bow of the vessel);27

26The NMFS’s Incidental Harassment Authorization (IHA), issued pursuant to 16 U.S.C. § 1371(a)(5), authorized the incidental “taking” of a

small number of marine mammals under the Marine Mammal Protection

Act (MMPA), 16 U.S.C. § 1361 et seq. The Deputy Secretary of Defense

incorporated the mitigation measures imposed by the NMFS into NDE I

issued pursuant to 16 U.S.C. § 1371(f), which exempted from the MMPA

for a period of six months all military readiness activities employing MFA

sonar, including the 2006 RIMPAC exercise. The NDE I imposed different mitigation measures for non-RIMPAC exercises during the six month

period, including the prohibition on use of MFA sonar within 12 nautical

miles of a coast. 

27Because the decibel is a logarithmic unit of acoustic power (using the

base-10 logarithm), a reduction in sonar level of 6 dB corresponds to a

reduction in sound intensity of approximately 75%, and a reduction in

sonar level of 10 dB corresponds to a reduction in sound intensity of 90%.

See Bird decl. ¶ 29. 

2106 NRDC v. WINTER
- the MFA sonar level is reduced by 10

dB if a marine mammal is detected

within 500 meters of the sonar dome;

and 

- the use of MFA sonar is stopped if a

marine mammal is detected within 200

meters of the sonar dome.28

• In conditions of strong surface ducting—where

sonar sound carries over a greater distance than

would otherwise be the case—the safety zones

will be expanded such that the MFA sonar level

is reduced by 6 dB if a marine mammal is

detected within 2,000 meters of the sonar dome

and by 10 dB if one is detected within 1,000

meters of the dome, and that the use of MFA

sonar is stopped if a marine mammal is detected

within 500 meters of the sonar dome. 

• In conditions of low visibility—i.e., whenever a

safety zone is not fully visible—additional detection measures will be used, such as infrared or

enhanced passive acoustic detection. If detection

of marine mammals is not possible out to the limits of the safety zone, the sonar level will be

reduced as if a marine mammal is present immediately beyond the extent of detection. 

• With the exception of three specific “choke

point” exercises, MFA sonar will not be operated

in constricted channels or canyon-like areas or

within 25 kilometers of the 200 meter isobath.29

28As one meter equals 1.094 yards, the sizes of the three safety zones

correspond to approximately 1,100 yards, 550 yards, and 220 yards,

respectively. 

29An isobath is a line (either imaginary or on a map) joining places

where water has equal depth. 

NRDC v. WINTER 2107
• During the three choke point exercises, additional

mitigation measures will be employed, including

two hours of pre-exercise monitoring for marine

mammals. 

Following the 2006 RIMPAC exercise, the Navy issued an

“after action report” in which it reported that it had used MFA

sonar for a total of 472 hours during the 2006 RIMPAC exercise and that the mitigation measures resulted in a loss of 8

hours of MFA sonar use.30 Dec. 7, 2006 Rim of the Pacific

After Action Report at 9. Although no unusual behavior of

marine mammals had been observed, the Navy reported that

of the estimated 256 marine mammals potentially affected by

the 472 hours of MFA sonar use, approximately 100 of them

had been precluded from exposure to MFA sonar as a result

of the mitigation measures. 

In October 2006, in anticipation of the SOCAL exercises,

the Navy submitted a consistency determination to the CCC,

seeking the CCC’s concurrence in the Navy’s determination

that the SOCAL exercises were consistent to the maximum

extent possible with the enforceable policies of the CCMP,

which, for purposes of the CZMA, are contained in the California Coastal Act. See Cal. Pub. Res. Code § 30008.31 The

CCC disagreed with the Navy that the use of MFA sonar in

the SOCAL exercises would not affect California’s coastal

resources. Accordingly, the CCC conditioned its concurrence

in the Navy’s consistency determination on the Navy adopting

30The Navy asserted in its “after action report” that 8 hours of lost MFA

sonar use translated into a somewhat greater amount of lost exercise time

because once the sonar is turned off, simply turning it back on does not

usually allow the Navy Commander to continue the exercise where it left

off. 

31The CZMA requires that a federal agency planning to conduct activities that may have reasonably foreseeable effects on California’s coastal

resources must apply to the CCC for a determination that those activities

are consistent to the maximum extent practicable with the enforceable policies of the CCMP. See 16 U.S.C. § 1456(c)(1)(C); 15 C.F.R. § 930.36. 

2108 NRDC v. WINTER
fourteen mitigation measures, several of which the Navy had

already employed in the 2006 RIMPAC exercise. The Navy

agreed to adopt only four of the CCC’s measures—all but one

of which do not actually prevent the use of MFA sonar from

harming marine mammals32 —and it refused to adopt the

remaining ten measures: 

• The measures used in the 2006 RIMPAC exercise

for reducing sonar levels during conditions of

low visibility; 

• The measures used in the 2006 RIMPAC exercise

in “choke points;” 

• Increasing the outer safety zone to 2 kilometers

even in conditions not involving strong surface

ducting;33

• Reducing sonar level by 6 dB during strong surface ducting conditions; 

32Following the CCC’s conditional concurrence, the Navy agreed to

adopt two of the CCC’s mitigation measures: retrieving inert dropped

mine shapes from the water and submitting to the CCC all monitoring

results provided to the NMFS. The mitigation measures set forth in the

EA, which have been standard operating procedure since 2004, appear to

include two other measures proposed by the CCC: requiring passive sonar

operators to monitor for marine mammals and report the detection of any

such mammals; and providing a report to the NMFS following a major

exercise that includes the results of marine mammal monitoring (a measure already employed in the 2006 RIMPAC exercise). The Navy concedes that the measure concerning dropped mine shapes “has nothing to

do with MFA sonar usage,” Dec. 20, 2007 Declaration of Rear Admiral

John M. Bird ¶ 13, and the two reporting requirements do not mitigate

actual harm to marine mammals but instead assist in the determination of

the impacts of the SOCAL exercises. See Feb. 4, 2008 Dist. Ct. Order at

6 n.7. Only the use of passive sonar to monitor for marine mammals mitigates the harm caused by the use of MFA sonar. 

33As stated above, the Navy had agreed to employ in the 2006 RIMPAC

exercise a 2,000 meter safety zone in strong surface ducting conditions. 

NRDC v. WINTER 2109
• Using two marine mammal observers who have

received NOAA-approved training for surveillance during use of MFA sonar; 

• Requiring aerial monitoring off San Clemente

Island throughout exercises involving MFA

sonar; 

• Monitoring for marine mammals for 30 minutes

prior to commencing use of MFA sonar; 

• Avoiding training in areas with known high concentrations of marine mammals; and 

• Locating and scheduling training outside the

migration season for the grey whale.34

In January 2007, the Deputy Secretary of Defense issued,

pursuant to 17 U.S.C. § 1371(f), a second National Defense

Exemption (“NDE II”), which exempted from the requirements of the MMPA all the Navy’s military readiness activities employing MFA sonar for the duration of the SOCAL

exercises. The Deputy Secretary of Defense conditioned the

exemption on the Navy adopting a number of mitigation measures, which already had been standard operating procedure in

the Navy’s ASW exercises since 2004. As the EA makes

clear, it is those mitigation measures, and only those measures, which the Navy adopted for the SOCAL exercises. 

While the Navy describes the adopted mitigation measures

as consisting of 29 separate measures, the district court found

that, in effect, they consist of only four basic measures: “(1)

personnel training (providing approved Marine Species

Awareness Training materials for lookouts and commanding

34The nine bullet points reflect the substance of the ten mitigation measures the Navy refused to adopt; two of the conditions have been consolidated in the fifth bullet point. 

2110 NRDC v. WINTER
officers), (2) on-deck lookouts, armed with binoculars or

night vision goggles, to watch for marine mammals, (3) operating procedures to ensure that any sightings of marine mammals are communicated up the chain of command, so that

MFA sonar is powered down [(i.e., sonar power is reduced)]

when a marine mammal approaches within 1,000 yards, 500

yards, and ‘secured’ (shut-down) at 200 yards,35 and (4) coordination and reporting procedures.” Feb. 4, 2008 Dist. Ct.

Order at 6 n.7. Our review of the EA reveals at most two

additional basic measures: that passive sonar will be used to

detect marine mammals and that Navy aircraft participating in

exercises will conduct surveillance when doing so does not

interfere with safety or the “accomplishment of primary operational duties.”

36 Notably, the measures adopted by the Navy

35We note that the Navy has recently agreed to slightly enlarge its safety

zones by applying safety zones of 1,000, 500 and 200 meters instead of

1,000, 500 and 200 yards. Bird decl. ¶ 58. As a result, those safety zones

are now of equal size as those employed in the 2006 RIMPAC exercise.

However, the Navy has not agreed to employ expanded safety zones in

strong surface ducting conditions. 

36The Navy also adopted a mitigation measure requiring “increased vigilance” during major ASW exercises using MFA sonar when “critical conditions” are present: a rapid change in bathymetry in areas of a certain

depth; where three or more vessels are operating MFA sonar in the same

area for six hours or more; where MFA sonar may “cut off” the exit route

for marine mammals from a bay or channel; and the historical presence of

a significant surface duct. However, in its June 2007 “after action report”

the Navy explained that it had assessed the conditions of the Southern California Operating Area and concluded that “the requirements stated in [the

aforementioned mitigation measure] do not apply to the physical conditions found in Southern California.” Accordingly, this mitigation measure

is not being employed in the SOCAL exercises and therefore does not, in

fact, mitigate the impact of MFA sonar on marine mammals during those

exercises. 

Similarly, the Navy adopted as a mitigation measure the requirement

that MFA sonar be operated “at the lowest practical level, not to exceed

235 dB, except as required to meet tactical training objectives.” However,

that requirement, also adopted for the 2006 RIMPAC exercise, has no

apparent mitigating effect because (1) it is not clear whether the Navy ever

NRDC v. WINTER 2111
do not include the ten aforementioned mitigation measures

recommended by the CCC, such as increasing the outer safety

zone to 2 kilometers, monitoring for marine mammals at least

30 minutes before commencing MFA sonar use, and conducting the SOCAL exercises outside the grey whale’s migratory

season and outside areas with high concentrations of marine

mammals. Moreover, the adopted measures do not include the

2006 RIMPAC measures requiring that MFA sonar not be

used in constricted channels and canyon-like areas or within

25 kilometers of the 200 meter isobath. Nor do they include

the requirement, imposed by NDE I for non-RIMPAC exercises in 2006, that MFA sonar not be used within 12 nautical

miles from the coastline.

Following our November 13, 2007 remand order, the district court set out to determine what narrowly-tailored mitigation measures should be imposed for the remaining SOCAL

exercises. In the words of the district court, NRDC proposed

“sweeping geographic exclusions” to the Navy’s use of MFA

sonar, including a 25 nautical mile coastal exclusion, locating

exercises to the maximum extent possible in waters deeper

than 1,500 meters, and an exclusion in the Catalina Basin, the

Westfall seamount, and the Cortez and Tanner Banks. Jan. 3,

2008 Dist. Ct. Order at 13 n.6. The Navy also proposed several mitigation measures. See id. 

After reviewing the parties’ briefs and taking a Navyguided tour of the USS Milius, the district court imposed six

mitigation measures in addition to those already required by

assumed higher sonar levels when using its harassment model to predict

harm to marine mammals, (2) the Navy’s interim report on the Bahamas

stranding indicates that sonar levels during the Bahamas exercise did not

exceed 235 dB even without the mitigation measure, and (3) the exception

that the Navy may exceed the 235 dB limit “as required to meet tactical

training objectives” swallows the rule, as tactical training objectives are

the only reason for using MFA sonar to begin with, thus allowing the

Navy to exceed the 235 dB limit whenever it in fact uses MFA sonar. 

2112 NRDC v. WINTER
NDE II: (1) the Navy shall suspend use of MFA sonar when

a marine mammal is detected within 2,200 yards from the

sonar source, except where the marine mammal is a dolphin

or a porpoise and it appears that the mammal is intentionally

following the sonar-emitting naval vessel in order to play in

or ride the vessel’s bow wave; (2) the Navy shall reduce the

MFA sonar level by 6 dB when significant surface ducting

conditions are detected;37 (3) the Navy shall not use MFA

sonar within 12 nautical miles from the California coastline;

(4) the Navy shall monitor, including by aircraft, for the presence of marine mammals for 60 minutes before employing

MFA sonar, shall utilize two dedicated, NOAA- and NMFStrained lookouts at all times when MFA sonar is being used,

shall employ passive acoustic monitoring to supplement

visual detection of the presence of marine mammals, and shall

use aircraft participating in the training exercises to monitor

for marine mammals for the duration of the exercises when

MFA sonar is being used; (5) Navy helicopters shall monitor

for marine mammals for 10 minutes before employing active

dipping sonar; and (6) the Navy shall refrain from using MFA

sonar in the Catalina Basin between the Santa Catalina and

San Clemente Islands because ingress and egress to the basin

are restricted and the basin has a high density of marine mammals. See Jan. 10, 2008 Dist. Ct. Order at 1-5. 

The district court rejected many of the geographic exclusions proposed by NRDC in favor of a 2,200-yard safety

zone, accepted the Navy’s representations that the bathymetry

off the shores of southern California presents unique training

opportunities, see Feb. 4, 2008 Dist. Ct. Order at 7, and

declined to limit the use of sonar at night or in conditions of

low visibility despite the Navy’s voluntarily adoption of such

limitations for the 2006 RIMPAC exercise, see Jan. 3, 2008

Dist. Ct. Order at 7-8. 

37The parties clarified at oral argument on February 27, 2008, that “significant” is the same as “strong,” the term used to modify surface ducting

conditions in the mitigation measures for the 2006 RIMPAC exercise. 

NRDC v. WINTER 2113
The Navy takes issue only with the first two of the mitigation measures imposed by the district court, namely the 2,200

yard “shutdown zone” and the “power-down” requirement

during significant surface ducting conditions. Specifically, the

Navy argues that those two mitigation measures tip the balance of hardships in its favor and are contrary to the public

interest. 

In support of its argument the Navy has submitted declarations by high-ranking officers attesting to the adverse consequences that those measures will have on the Navy’s military

readiness. For example, Vice Admiral Locklear, Commander

of the U.S. Third Fleet, opines that “imposing a 2200-yard

shutdown zone will have crippling implications on Navy’s

ability to conduct realistic pre-deployment ASW training

employing MFA sonar” and will “jeopardize the training and

readiness of U.S. THIRD Fleet [strike groups].” Declaration

of Vice Admiral Samuel J. Locklear. ¶¶ 9, 13. Likewise, Rear

Admiral Bird opines that “[t]raining in surface ducting conditions is critical to effective training.” Bird decl. ¶ 52. In their

classified declarations, Admiral Gary Roughead and Rear

Admiral Ted N. Branch opine that both the 2200-yard shutdown zone and the power-down requirement in significant

surface ducting conditions will create an unacceptable risk

with respect to the Navy’s ability to certify its strike groups

as combat ready and will thus profoundly affect national

security. 

III. Standards of Review

Our review of a district court’s grant of a preliminary

injunction is “very deferential.” Nat’l Wildlife Fed’n v. Nat’I

Marine Fisheries Serv., 422 F.3d 782, 794 (9th Cir. 2005).

We do not reverse the district court unless it “relie[s] on an

erroneous legal premise or abuse[s] its discretion.” Sports

Form, Inc. v. United Press Int’l, Inc., 686 F.2d 750, 752 (9th

Cir. 1982) (internal citations omitted). A court abuses its discretion if it bases its decision on an erroneous legal standard

2114 NRDC v. WINTER
or clearly erroneous findings of fact. Earth Island Inst. v. U.S.

Forest Serv., 442 F.3d 1147, 1156 (9th Cir. 2006) (“Earth

Island II”). 

A district court may grant a preliminary injunction if one

of two sets of criteria are met. “Under the ‘traditional’ criteria,

a plaintiff must show (1) a strong likelihood of success on the

merits, (2) the possibility of irreparable injury to plaintiff if

preliminary relief is not granted, (3) a balance of hardships

favoring the plaintiff, and (4) advancement of the public interest (in certain cases). Alternatively, a court may grant the

injunction if the plaintiff demonstrates either a combination of

probable success on the merits and the possibility of irreparable injury or that serious questions are raised and the balance

of hardships tips sharply in his favor.” Freecycle Network,

Inc. v. Oey, 505 F.3d 898, 902 (9th Cir. 2007); see also Earth

Island II, 442 F.3d at 1158. 

IV. Discussion

A. Likelihood of Success on the Merits

1. Effect of CEQ’s Alternative Arrangements for

NEPA Compliance

On January 15, 2008 CEQ purported to approve “alternative arrangements” for the Navy to continue its use of MFA

sonar while complying with NEPA, reasoning that “emergency circumstances” prevented normal compliance. CEQ’s

authority to grant such relief derives from 40 C.F.R.

§ 1506.11, which provides in full: 

Where emergency circumstances make it necessary

to take an action with significant environmental

impact without observing the provisions of these

regulations, the Federal agency taking the action

should consult with the Council about alternative

arrangements. Agencies and the Council will limit

NRDC v. WINTER 2115
such arrangements to actions necessary to control the

immediate impacts of the emergency. Other actions

remain subject to NEPA review. 

40 C.F.R. § 1506.11. CEQ’s letter of explanation to the Navy

stated that the district court’s modified injunction “imposes

training restrictions . . . that continue to create a significant

and unreasonable risk that Strike Groups will not be able to

train and be certified as fully mission capable.” CEQ Letter

to Donald C. Winter at 3. CEQ also stated that “the inability

to train effectively with MFA sonar puts the lives of thousands of Americans directly at risk. . . . Therefore, there are

urgent national security reasons for providing alternative

arrangements under the CEQ regulations.” Id. at 3-4. 

The Navy then petitioned this court to vacate the district

court’s preliminary injunction, arguing that CEQ’s approval

of “alternative arrangements” deprived NRDC of the “likelihood of success on the merits” of its NEPA claims, thus eliminating the legal basis for the injunction. We remanded to the

district court to allow it to consider in the first instance

whether this legal development merited vacatur or a partial

stay of the injunction. 

On remand, the Navy maintained that the CEQ’s “emergency circumstances” determination relieved it of the requirement to prepare an EIS prior to commencing the remaining

SOCAL exercises. NRDC argued that CEQ’s action was

beyond the scope of the regulation and otherwise invalid, and

that the preliminary injunction should remain in place. The

district court considered these arguments and concluded that

its preliminary injunction was “not affected by [CEQ’s]

approval of emergency alternative arrangements because there

is no emergency.” Feb. 4, 2008 Dist. Ct. Order at 2. Accordingly, it held that “CEQ’s action is beyond the scope of the

regulation and is invalid[ ]” and that “[t]he Navy is not, therefore exempted from compliance” with NEPA and the preliminary injunction. Id. The district court found that CEQ’s

2116 NRDC v. WINTER
interpretation of “emergency circumstances” to include a

court order entered in the course of pending litigation was not

authorized by 40 C.F.R. §1506.11, because it was contrary to

both the plain meaning of “emergency circumstances” and the

drafters’ original intent. It also found that CEQ’s action was

contrary to the governing statute, NEPA.38

The Navy makes two basic arguments as to why the district

court erred by failing to vacate the preliminary injunction in

light of CEQ’s approval of “alternative arrangements.” First,

the Navy argues that the district court lacked subject matter

jurisdiction to review CEQ’s approval of alternative arrangements because such approval constitutes a superseding agency

action that removes as moot any basis for an injunction predicated on plaintiffs’ original claims concerning the Navy’s EA.

Second, the Navy argues that, even if the district court could

review CEQ’s action, the court erred by not deferring to

CEQ’s and the Navy’s assessment that “emergency circumstances” exist within the meaning of 40 C.F.R. § 1506.11. We

address the Navy’s arguments in turn.

a. Subject Matter Jurisdiction over NRDC’s Challenge

to CEQ’s Action

[1] The Navy argues that the district court lacked subject

matter jurisdiction to consider the validity of CEQ’s action

because that action allegedly moots the plaintiffs’ original

claims. Specifically, the Navy contends that the adoption of

CEQ’s “alternative arrangements” in a superseding Decision

Memorandum constitutes a new administrative action, which

can only be challenged by a new claim on the merits. See Rat38The district court also noted that CEQ had essentially crafted its own,

alternative injunction, which suggested that CEQ, as an executive body,

was effectively “sitting in review of a decision of the judicial branch.” The

district court observed that CEQ’s actions raised “serious constitutional

concerns under the Separation of Powers doctrine,” but it declined, pursuant to the doctrine of constitutional avoidance, to make a finding as to the

constitutionality of its action. See Feb. 4, 2008 Dist. Ct. Order at 24. 

NRDC v. WINTER 2117
tlesnake Coalition v. EPA, 509 F.3d 1095, 1103-04 (holding

that the district court lacked subject matter jurisdiction over

new final agency action).39 The district court implicitly

rejected this argument by continuing to exercise jurisdiction

over the plaintiffs’ NEPA claim. Its decision to do so is firmly

grounded in the familiar principle that only a valid subsequent

action can render a legal claim moot. See Adarand Constructors, Inc. v. Slater, 528 U.S. 216, 222-23 (2000); United

States v. Larson, 302 F.3d 1016, 1020 (9th Cir. 2002) (“The

stipulation moots [plaintiff’s] challenge to the suppression

ruling only if it is valid.”). Accordingly, the district court did

not rely on an erroneous legal premise or abuse its discretion

in concluding that it had jurisdiction to assess the validity of

the new action in order to determine whether plaintiffs’ original claims could survive. See Adarand, 528 U.S. at 222-23. 

[2] Nor did the district court abuse its discretion by leaving

in place the preliminary injunction after determining that

CEQ’s action did not require its vacatur. The Navy’s contention that the district court issued “an entirely new injunction

. . . based on new, ancillary claims” mischaracterizes the posture of this case. The Navy challenged the injunction based on

39Notably, none of the cases that the Navy cites in support of this argument involve a plaintiff’s challenge to the validity of a new agency action.

For example, in Forest Guardians v. U.S. Forest Serv., 329 F.3d 1089,

1096 (9th Cir. 2003), plaintiffs’ claims were rendered moot because the

superseding and controlling environmental documentation that displaced

the earlier agency action did not rely on the challenged assumptions that

formed the basis of plaintiffs’ claims. In W. Radio Serv. Co. Inc. v. Glickman, 113 F.3d 966, 974 (9th Cir. 1997), a challenge to a letter postponing

the issuance of certain permits until a fee structure was established was

rendered moot by the subsequent issuance of a fee structure. In Aluminum

Co. of Am. v. Bonneville Power Admin., 56 F.3d 1075 (9th Cir. 1995),

challenges to a 1993 Rule of Decision were moot because augmentations

were being issued under a subsequent Rule of Decision. Finally, in Oregon Natural Res. Council v. Harrell, 52 F.3d 1499, 1501-02, 1508 (9th

Cir. 1995), the district court ordered a challenged ROD withdrawn

because it was incomplete, and a subsequent challenge to that nonoperative ROD was thus held to be moot. 

2118 NRDC v. WINTER
CEQ’s action; NRDC argued only that CEQ’s action did not

change the merits of its NEPA claims. Thus, the district court

here did not “[g]rant[ ] a preliminary injunction based on a

showing that the plaintiffs were likely to succeed in establishing a violation of an ancillary court order, rather than a showing that they were likely to succeed on the merits of any of

their claims.” Alabama v. U.S. Army Corps of Engineers, 424

F.3d 1117, 1135 (11th Cir. 2005). 

b. The District Court’s Assessment of Whether

“Emergency Circumstances” Existed

(1) Deference

The district court concluded that CEQ’s interpretation of 40

C.F.R. § 1506.11 is not entitled to deference. It reasoned that

under the Administrative Procedure Act (“APA”), 5 U.S.C.

§ 551 et seq., the courts traditionally afford deference to (1)

an agency’s reasonable interpretation of a statute it administers “if the statute is silent or ambiguous with respect to the

specific issue . . . ,” citing Chevron, U.S.A., Inc. v. NRDC, 467

U.S. 837, 843 (1984), and (2) an agency’s interpretation of its

own regulations unless “an alternative reading is compelled

by the regulation’s plain language or by other indications of

the [agency’s] intent at the time of the regulation’s promulgation,” citing Thomas Jefferson Univ. v. Shalala, 512 U.S. 504,

512 (1994), and Bowles v. Seminole Rock & Sand Co., 325

U.S. 410, 414 (1945). See Feb. 4, 2008 Dist. Ct. Order at 13-

14. 

NRDC challenged neither the propriety of CEQ’s original

promulgation of 40 C.F.R. § 1506.11 nor the fact that

§ 1506.11 allows alternative arrangements for compliance

with NEPA under genuine emergency circumstances. Instead,

NRDC limited its challenge to CEQ’s application of the regulation to the facts of this case. Accordingly, the district court

considered whether the term “emergency circumstances”

could be afforded so broad an interpretation as to encompass

NRDC v. WINTER 2119
the Navy’s need to continue its long-planned, routine sonar

training exercises without the mitigation measures imposed

by the district court. The district court concluded that the

plain language of the regulation and the limited indicia of the

agency’s original intent compelled a narrower interpretation

of “emergency circumstances” than the one afforded it by

CEQ. Accordingly, the district court concluded that it did not

owe deference to CEQ’s interpretation of § 1506.11 under

Thomas Jefferson and Seminole Rock. We review that conclusion to determine whether in so doing it relied on an erroneous legal premise or abused its discretion; we conclude that

it did neither. 

[3] The district court followed established Supreme Court

precedent in finding that an agency’s interpretation of its own

regulation is not entitled to deference when it is inconsistent

with the regulation itself, conflicts with agency intent at the

time of promulgation, and reaches beyond “the limits imposed

by the statute,” NEPA. See Auer v. Robbins, 519 U.S. 452,

461-63 (1997). Next, the district court, after concluding that

the meaning of “emergency circumstances” was clear, applied

the appropriate legal principles that an agency’s interpretation

of its own regulation is entitled to deference “only when the

language of the regulation is ambiguous.” See Christensen v.

Harris County, 529 U.S. 576, 588 (2000). Accordingly, the

district court did not abuse its discretion when it determined

not to give deference to CEQ’s overly broad interpretation of

“emergency circumstances.”

40

40The district court also held that Skidmore deference is inapplicable

because this case involves an agency’s interpretation of a regulation, not

its informal interpretation of a statute it administers. See Feb. 4, 2008 Dist.

Ct. Order at 19 n.13 (rejecting plaintiffs’ argument that because it does not

arise out of formal rulemaking, CEQ’s interpretation is entitled to little or

no deference under Skidmore v. Swift & Co., 323 U.S. 134, 140 (1944)).

While this holding is correct as a matter of law, our determination that the

district court neither abused its discretion nor relied on an erroneous legal

premise in concluding that no deference is owed CEQ’s overly broad

interpretation of “emergency circumstances” renders this issue moot. 

2120 NRDC v. WINTER
(2) Plain Meaning and Intent of CEQ Regulation

In finding that no emergency circumstances existed, the

district court reasoned that the “Navy’s current ‘emergency’

is simply a creature of its own making, i.e., its failure to prepare adequate environmental documentation in a timely fashion, via the traditional EIS process or otherwise.” Feb. 4, 2008

Dist. Ct. Order at 17. In short, it was not a sudden unanticipated event. The district court supported its conclusion by

noting that the CEQ letter does not specify an “emergency”

other than the district court’s mitigation order itself, which, in

CEQ’s view, creates a “significant and unreasonable risk” that

strike groups will not be able to train and be certified as fully

mission capable. Id. at 16-17. 

[4] On appeal, the Navy argues that “no matter its genesis[,] . . . the inability to certify its west coast-based strike

groups for deployment to hostile areas overseas during a time

of war” is a pressing national emergency. The Navy cites to

declarations, including one of the Chief of Naval Operations,

that attests to the national security impacts of such a failure

at a time when the United States is currently engaged in war

in two countries. The Navy contends that the district court’s

view that the term “emergency circumstances” as used in the

regulation per se excludes the circumstances presented here is

an impermissible substitution of its judgment for that of multiple federal agencies (citing Ass’n of Pac. Fisheries v. EPA,

615 F.2d 794, 810-11 (9th Cir. 1980)). We reject this argument and hold, for the reasons explained above, that the district court did not abuse its discretion in determining that the

plain meaning of “emergency circumstances” precludes an

interpretation so broad as to encompass the Navy’s need to

continue long-planned, routine training exercises without mitigation measures ordered by the court. 

[5] There is ample support for the manner in which the district court exercised its discretion. The district court properly

relied on dictionary definitions of “emergency” and “emerNRDC v. WINTER 2121
gency circumstances” to support its conclusion that CEQ’s

interpretation is not entitled to deference. See Watson v.

United States, 128 S. Ct. 579, 583 (2007) (noting that terms

are construed consistently with their everyday meaning,

including by reference to the dictionary absent statutory definition or definitive clue). As the district court observed, the

Oxford English Online Dictionary defines “emergency” as

“[t]he arising, sudden or unexpected occurrence (of a state of

things, an event, etc.).” Oxford English Online Dictionary,

available at http://dictionary.oed.com. Black’s Law Dictionary defines the term “emergency circumstances,” through a

cross-reference to “exigent circumstances,” as “[a] situation

that demands unusual or immediate action and that may allow

people to circumvent usual procedures, as when a neighbor

breaks through a window of a burning house to save someone

inside.” Blacks Law Dictionary 260, 562 (8th ed. 2004)

(emphasis added). The district court did not abuse its discretion in concluding that the circumstances in the present case

fall outside the scope of these definitions because its preliminary injunction was entirely predictable given the parties’ litigation history. Feb. 4, 2008 Dist. Ct. Order at 15.41

The Navy urges that the risk to national security created by

the preliminary injunction falls squarely within the legal definition of “emergency circumstances.” However, the Navy has

been on notice of its possible legal obligations to prepare an

EIS for the SOCAL exercises from the moment it first

41NRDC provides several more dictionary definitions of “emergency,”

all of which include the terms “unexpected” or “unforseen.” The Navy

refers us to another source that defines “emergency” as “a situation

demanding immediate attention.” Random House Dict. of the English

Lang. 636 (2d ed. 1987). We do not adjudicate the meaning of the word

“emergency” here. Rather, we need conclude only that the district court

did not rely on erroneous legal principles or abuse its discretion in reaching its determination as to that term’s plain meaning. Because we are not

“left with the definite and firm conviction that a mistake has been committed[,]” we leave the district court’s determination intact. Sports Form, Inc.,

686 F.2d at 752. 

2122 NRDC v. WINTER
planned those exercises. In addition, NRDC filed its complaint almost a year ago, and on August 7, 2007, the district

court held that the Navy was likely to lose on the merits of

NRDC’s claims. We affirmed that ruling in November of

2007. Still, the Navy waited until January 10, 2008, to raise

a cry of “emergency” and request the NEPA and CZMA

waivers it relies on here, in order to continue its routine,

planned training exercises. We find no abuse of discretion in

the district court’s determination that such a series of events

gives rise to a predictable outcome, not an unforeseeable one

demanding “unusual or immediate action.” 

Moreover, the district court’s conclusion finds support in

CEQ’s recent response to Hurricane Katrina. In March 2006,

CEQ approved alternative arrangements to allow the Federal

Emergency Management Agency to respond on an emergency

basis to “[d]amages to the critical physical infrastructure in

the New Orleans Metropolitan Area from the impact of Hurricanes Katrina and Rita [that] rendered parts of the city inoperable and uninhabitable.” NEPA Alternative Arrangements for

Critical Physical Infrastructure in New Orleans, 71 Fed. Reg.

14712, 14713 (March 23, 2006). The alternative arrangements

explain that generally, such arrangements are made when

“emergency circumstances require taking actions with significant environmental impacts and there is not sufficient time to

follow the regular [EIS] process.” Id. (emphasis added). This

language supports the district court’s view that the words

“emergency circumstances” in 40 C.F.R. § 1506.11 refer to

unexpected, suddenly arising situations that require agency

action in a shorter time frame than would be required to prepare an EIS. By contrast, the Navy’s routine SOCAL exercises were planned well in advance and with “sufficient time

to follow the regular [EIS] process.” 

In concluding that the Navy’s failure to comply timely with

NEPA does not constitute an “emergency circumstance”

within the meaning of 40 C.F.R. § 1506.11, the district court

also relied on the limited drafting history of the regulation. As

NRDC v. WINTER 2123
the district court pointed out, the initial proposed version of

the regulation required an agency “proposing to take” an

emergency action to consult with CEQ regarding alternative

arrangements.42 See Proposed Implementation of Procedural

Provisions, 43 Fed. Reg. 25230, 25243 (June 9, 1978)

(emphasis added). However, the drafters changed “proposing

to take” to “taking” in order to remove the inference that consultation must necessarily precede agency action because

“such a requirement might be impractical in emergency circumstances and could defeat the purpose of the section.”

Implementation of Procedural Provisions; Final Regulations,

43 Fed. Reg. 55978, 55988 (Nov. 29, 1978). While the Navy

dismisses this drafting history as reflecting only that “the proposed regulation was broadened to allow actions to be taken

prior to consultation with CEQ,” we find no abuse of discretion in the district court’s contrary conclusion that the regulatory history “supports a narrow, rather than a broad

interpretation of the phrase ‘emergency circumstances’ ” and

that the regulatory history reflects CEQ’s intent to use the regulation to accommodate “sudden unanticipated events” but

not more predictable events such as provisionally unfavorable

litigation results. Feb. 4, 2008 Dist. Ct. Order at 19. 

Accordingly, we conclude that the district court did not rely

on an erroneous legal premise or abuse its discretion in finding that the Navy’s attempt to characterize a federal court

injunction as an “emergency circumstance” is contrary to the

plain meaning of the language and to the intended purpose of

CEQ’s emergency circumstances regulation.43

42In its analysis of the agency’s intent, the district court appropriately

declined to consider the declaration of Nicholas C. Yost, CEQ general

counsel at the time the regulation was drafted, as “an unreliable guide” to

CEQ’s intent, comparing the declaration to “subsequent legislative history.” Feb. 4, 2008 Dist. Ct. Order at 18-19 (quoting Chapman v. United

States, 500 U.S. 453, 464 n.4 (1991) (internal citations omitted)). 

43NRDC makes the additional argument that CEQ’s order goes beyond

the scope of the regulation because the “alternative arrangements,” pre2124 NRDC v. WINTER
(3) Prior Decisions

[6] Prior judicial decisions also support our conclusion that

the district court did not rely on erroneous legal premises or

abuse its discretion in concluding that CEQ’s action is invalid.

In each of the cases sustaining an application of 40 C.F.R.

§ 1506.11, CEQ allowed “alternative arrangements” in

response to unanticipated emergencies that required federal

agencies to respond quickly to new and changing events. 

For example, in Valley Citizens for a Safe Environment v.

Vest, the court upheld “alternative arrangements” which permitted the Air Force to fly C-5A transport planes into and out

of Westover Air Force Base on a twenty-four hour schedule,

despite a previously prepared EIS’s prohibition of such

flights. 1991 WL 330963 (D. Mass. May 30, 1991). The court

in Valley Citizens denied the plaintiffs’ request for an injunction until a supplemental EIS was completed because it concluded that the modified flight schedule was essential to

supply military equipment and personnel for Operation Desert

Storm, an emergency response to Iraq’s sudden invasion of

Kuwait that same month. Id. at *5-6. The court agreed with

the determination of CEQ and the Air Force that Iraq’s invasion of Kuwait reasonably constituted an emergency “given

the military’s operational and scheduling difficulties and the

hostile and unpredictable nature of the Persian Gulf region.”

Id. at *5. 

Other cases sustaining CEQ’s application of 40 C.F.R.

§ 1506.11 also support the district court’s narrow interpretation of the phrase “emergency circumstances.” Courts have

scribed prospectively through January 2009, go beyond those “actions

necessary to control the immediate impacts of the emergency,” even if

there were an emergency. Because we hold that there is no basis for

reversing the district court’s determination that there were no “emergency

circumstances” under 40 C.F.R. § 1506.11, and therefore no basis for

CEQ’s order, we do not reach the merits of this argument. 

NRDC v. WINTER 2125
routinely given deference to CEQ’s finding of “emergency

circumstances” in situations where that finding has been used

to “avert imminent crises outside the agency’s control.” Id. at

17; see, e.g., Nat’l Audobon Society v. Hester, 801 F.2d 405,

405-7 (D.C. Cir. 1986) (giving deference where immediate

action was necessary to prevent the extinction of the California condor); Miccousukee Tribe of Indians of Fla. v. United

States, 509 F.Supp.2d 1288, 1290-91 (S.D. Fla. 2007) (giving

deference where immediate deviation from a water delivery

method was necessary to avoid pending extinction of the

Cape Sable seaside sparrow in the Everglades); NRDC v.

Pena, 20 F.Supp.2d 45, 50 (D.D.C. 1998) (giving deference

where immediate action was necessary to secure storage of

nuclear materials); Crosby v. Young, 512 F.Supp. 1363, 1380,

1386 (E.D. Mich. 1981) (where an immediate response was

required for a city to meet a federal funding deadline for a

development project to counteract potentially dire economic

effects of the closure of a General Motors plant). In looking

to prior decisions, the district court certainly did not apply an

erroneous legal principle. Rather, it found legal authority that

supported its view. 

(4) CEQ’s Broad Reading of “Emergency

Circumstances” and NEPA

The district court also held that CEQ’s broad reading of

“emergency circumstances” here is ultra vires because it subverts NEPA’s directive that agencies perform their NEPA

duties “to the fullest extent possible.”

44 See 42 U.S.C. § 4332.

The existence of specific Congressional exemptions to NEPA

informed the district court’s decision not to read the regulation “so broadly as to independently authorize CEQ to do the

same, in the absence of a legitimate ‘emergency.’ ” Feb. 4,

2008 Dist. Ct. Order at 21. Moreover, the court noted that

44Moreover, NEPA also requires agencies to use “all practicable means

and measures” to fulfill their duties under it. 42 U.S.C. § 4331(b). 

2126 NRDC v. WINTER
many of the exemptions granted in other cases involved agencies faced with conflicting Congressional mandates. Id. at 22.

NEPA, the statute authorizing 40 C.F.R. § 1506.11,

requires federal agencies to prepare an EIS for a major federal

action “significantly affecting the quality of the human environment,” 42 U.S.C. § 4332(2)(C), or, in the alternative, to

implement mitigation measures to minimize impacts to the

point where an EIS in not required. See, e.g., Nat’l Parks &

Conservation Ass’n v. Babbitt, 241 F.3d 722, 734 (9th Cir.

2001). Although CEQ justified its approval of “alternative

arrangements” to satisfy NEPA as grounded in “urgent

national security” concerns, see Jan. 15, 2008 CEQ Letter at

4, the district court noted that, in the absence of a bona fide

emergency, the “alternative arrangements” “operate[ ] to

exempt [the Navy] from the ususal rigors involved in the

preparation of an EIS, which forms the ‘heart’ of NEPA.”

Feb. 4, 2008 Dist. Ct. Order at 21 n.14 (quoting Envtl. Def.

Fund, Inc. v. Andrus, 619 F.2d 1368, 1374-5 (10th Cir.

1980)). 

Reviewing CEQ’s justification in this light, the district

court concluded that CEQ’s broad reading of “emergency circumstances” has the effect of reading a “national security” or

“defense” exemption into NEPA, where none exists.45 As the

45Moreover, the district court’s conclusion was grounded in the wellestablished fact that there is no “national defense” exception to NEPA. See

San Luis Obispo Mothers for Peace v. Nuclear Regulatory Comm’n, 449

F.3d 1016, 1035 (9th Cir. 2006); No GWEN Alliance of Lane County, Inc.

v. Aldridge, 855 F.2d 1380, 1384 (9th Cir. 1988). “ ‘The Navy, just like

any federal agency, must carry out its NEPA mandate to the fullest extent

possible and this mandate includes weighing the environmental costs of

the [project] even though the project has serious security implications.’ ”

San Luis Obispo, 449 F.3d at 1035 (quoting No GWEN, 855 F.2d at 1384).

Indeed, Congress has included exemptions for “paramount” national

security concerns in many environmental statutes, but not in NEPA. See,

e.g., Toxic Substances Control Act, 15 U.S.C. § 2621 (compliance waived

if the President determines a requested waiver to be necessary “in the

NRDC v. WINTER 2127
district court pointed out, Congress knows well how to

exempt planned Defense Department activities from the

requirements of NEPA. See, e.g., Nat’l Defense Auth. Act,

Pub. L. No. 106-398, § 317, 114 Stat. 1654, 1654A-57 (2000)

(specifically exempting Defense Department from preparing

nationwide EIS for low-level flight training). The fact that

Congress has not so exempted the Navy’s exercises in the

Southern California Operating Area further supports the district court’s conclusion that 40 C.F.R. § 1506.11 should not be

read to exempt the routine SOCAL exercises from NEPA’s

requirements. 

The district court’s interpretation also comports with wellestablished Supreme Court precedent that narrowly interprets

NEPA’s requirement that agencies comply with its provisions

“to the fullest extent possible.” The Supreme Court has made

clear that the “to the fullest extent possible” language was

intended to address only cases in which there is an “irreconcilable and fundamental conflict” between NEPA’s requireinterest of national defense”); Coastal Zone Management Act, 16 U.S.C.

§ 1456(c)(1)(b) (under certain circumstances the President may exempt an

activity that is in the “paramount interest of the United States”); Endangered Species Act, 16 U.S.C. § 1536(j) (exemption granted if the Secretary of Defense finds such exemption necessary “for reasons of national

security”); Clean Water Act, 33 U.S.C. § 1323(a) (the President may

exempt federal effluent source for up to one year if in the “paramount

interest of the United States”); Safe Drinking Water Act, 42 U.S.C. § 300j6(a) (the President may exempt federal facility for up to one year if in the

“paramount interest of the United States”); Resource Conservation and

Recovery Act, 42 U.S.C. § 6961(a) (the President may exempt federal

solid waste management facility for up to one year if in the “paramount

interest of the United States”); Clean Air Act, 42 U.S.C. § 7417(b) (the

President may exempt federal emission source for up to one year if in the

“paramount interest of the United States”); Comprehensive Environmental

Response, Compensation and Liability Act, 42 U.S.C. § 9620(j) (the President may issue orders to exempt facilities of the Department of Energy

and the Department of Defense “as may be necessary to protect the

national security interests of the United States . . .”). See Oct. 1, 2007

Brief of Amicus Curiae Law Professors Hope Babcock, et al. at 16 & n.4.

2128 NRDC v. WINTER
ments and the requirements of another statute. See Flint Ridge

Dev. Co. v. Scenic Rivers Ass’n. of OK, 426 U.S. 776, 787-88

(1976). Here, as the district court noted, the Navy has never

contended that it could not reconcile the district court’s

injunction with the requirements of NEPA. 

Similarly, NEPA regulations interpret the language “to the

fullest extent possible” to mean that “each agency of the Federal Government shall comply with that section unless existing law . . . expressly prohibits or makes compliance

impossible.” 40 C.F.R. § 1500.6. The legislative history of

§ 1500.6 explains that this language “shall not be used by any

Federal agency as a means of avoiding compliance with

[NEPA’s] directives . . . .” 115 Cong. Rec. (Part 29) 39702-

39703 (1969); see also Calvert Cliffs’ Coordinating Comm.

Inc. v. U.S. Atomic Energy Comm’n, 449 F.2d 1109, 1114

(D.C. Cir. 1971) (“We must stress as forcefully as possible

that this language does not provide an escape hatch for footdragging agencies; it does not make NEPA’s procedural

requirements somehow ‘discretionary.’ . . . Indeed, [the language] sets a high standard for the agencies, a standard which

must be rigorously enforced by the reviewing courts.”). 

The Navy asserts that national policy requires that it must

be confident that its west coast-based strike groups are prepared and certified for deployment to hostile areas overseas

during a time of war. However, as the district court noted,

nothing prevented the Navy from preparing an EIS prior to

commencing the SOCAL exercises; indeed, the fact that the

Navy is currently developing an EIS for exercises in the

Southern California Operating Area confirms that it is fully

capable of meeting NEPA’s requirements. See Notice of

Intent To Prepare an Environmental Impact Statement/

Overseas Environmental Impact Statement for the Southern

California Range Complex, 71 Fed. Reg. 76,639 (Dec. 21,

2006). 

NRDC v. WINTER 2129
Although the Navy argues that “NEPA must give way” so

that it may proceed with its training and certification unhindered by environmental rules, quoting Flint Ridge, 426 U.S.

at 788, Flint Ridge itself holds that NEPA’s procedural

requirements are not discretionary and do not give way unless

a “clear and unavoidable conflict in statutory authority

exists,” id, here, the district court carefully examined the

record, with which it has longstanding familiarity, and determined that there was no such conflict in statutory authority,

concluding that conditioning phrases like “consistent with

other essential considerations of national policy,” 42 U.S.C.

§4331(b), and “to the fullest extent possible,” id. §4332, do

not indicate Congressional intent to create a statutory escape

hatch. Nor does any intent appear in the implementing regulations, that would allow the Navy to conduct its exercises

before completing an EIS.46 Feb. 4, 2008 Dist. Ct. Order at

22-23. 

In reaching these conclusions, the district court examined

the various legal rules and applied those that were relevant to

this proceeding. Having done so, it acted well within its discretion in determining that CEQ’s broad interpretation of

“emergency circumstances” is contrary to the dictates of

NEPA. 

(5) Additional Considerations

We also note that NRDC has raised a serious question as

to whether CEQ acted arbitrarily and capriciously in the procedure it used to reach its “emergency circumstances” determination pursuant to 40 C.F.R. § 1506.11. The Navy, arguing

46The Navy argues, in the alternative, that CEQ’s action comports with

NEPA because it actually gives effect to the district court’s conclusion

that an EIS is likely required and provides “alternative arrangements” as

a bridge until the agency completes this EIS. Because we have concluded

that the district court did not abuse its discretion in determining that no

emergency existed and that CEQ had no authority to issue its order, we

need not reach this argument. 

2130 NRDC v. WINTER
that the district court’s order created an emergency by compromising its ability to effectively train and certify its strike

groups, requested alternative arrangements on January 10,

2008, and submitted evidence supporting that request the following day. Jan. 15, 2008 CEQ Letter at 1. CEQ approved the

Navy’s request four days later, on January 15, 2008. Id. In the

intervening time, CEQ held discussions with, and received

briefings from, the Navy and NMFS and reviewed the Navy’s

supporting documents. Id. at 4. At no point did CEQ request,

nor did the Navy provide it, any of the evidence in the district

court record contrary to the Navy’s position that the challenged mitigation measures would compromise its ability to

train and certify its strike groups. Thus, CEQ reached its

“emergency circumstances” determination without considering any of the substantial evidence on which the district court

relied in concluding that the mitigation measures it imposed

would not render the Navy unable to train and certify its strike

groups. Where, as here, the basis for an emergency is alleged

to be the effect of a district court order, entered after careful

review of a full record submitted by both parties, a substantial

question exists as to whether CEQ acted arbitrarily and capriciously when it failed to review the full record, and instead

considered only one side’s views, and on that basis determined that the court’s order gave rise to “emergency circumstances.”47

47CEQ’s action raises a serious question not only under the APA, but

also under the Constitution. The separation of powers doctrine prevents

Congress from vesting review of the decisions of Article III courts in the

Executive Branch. See Plaut v. Spendthrift Farm, Inc., 514 U.S. 211, 218-

19 (1995) (explaining that Article III “gives the Federal Judiciary the

power, not merely to rule on cases, but to decide them, subject to review

only by superior courts in the Article III hierarchy”); see also Hayburn’s

Case, 2 U.S. (2 Dall.) 409, 410 (1792). Here, the Navy represented, and

CEQ determined, that “emergency circumstances” existed because the district court’s preliminary injunction prevented the Navy from effectively

training and certifying its strike groups for deployment. In making this

determination, CEQ presumably reviewed the same evidence that the

Navy presented to the district court (without, as noted above, the benefit

of NRDC’s evidence) and concluded, despite the district court’s explicit

NRDC v. WINTER 2131
(6) Conclusion

[7] For the foregoing reasons, we hold that the district court

did not abuse its discretion or rely on an erroneous legal

premise in determining that CEQ’s broad interpretation of

“emergency circumstances” was not authorized by 40 C.F.R.

§ 1506.11 because it was contrary to the plain meaning of the

regulation and contrary to NEPA and, accordingly, that the

Navy remains subject to the traditional requirements of

NEPA.

factual finding to the contrary, that the imposed mitigation measures

would compromise the Navy’s ability to train and certify its forces. We

find substantial merit in NRDC’s argument that even if the district court’s

factual findings with respect to the effect of its mitigation measures were

erroneous, it was the job of the appellate court—and not the Executive

Branch—to so conclude. However, because the district court declined to

reach this question, we, too, do not consider the constitutional argument

in determining that the district court did not rely on an erroneous legal

premise or abuse its discretion when it held that CEQ’s action was invalid.

2132 NRDC v. WINTER
Volume 2 of 2

NRDC v. WINTER 2133
2. NRDC’s NEPA Claim

We next address the district court’s conclusion that NRDC

has shown probable success on the merits of its claim that the

Navy violated NEPA by failing to prepare an EIS for the

SOCAL exercises. 

In our November 13, 2007 order we concluded that “Plaintiffs have shown a strong likelihood of success on the merits

of their claims under [NEPA].” NRDC, 508 F.3d at 886.

While that conclusion was based on our review of the record

underlying the district court’s August 7, 2007 preliminary

injunction order, the only subsequent developments are

CEQ’s approval of “alternative arrangements” pursuant to 40

C.F.R. § 1506.11 and the Navy’s concession, by virtue of

seeking such approval, that the SOCAL exercises will have a

“significant environmental impact.” See 40 C.F.R. § 1506.11

(“Where emergency circumstances make it necessary to take

an action with significant environmental impact without

observing the provisions of these regulations, the Federal

agency taking the action should consult with the Council

about alternative arrangements.”) (emphasis added). Although

we elaborate on our reasons, our original conclusion remains

unchanged.

2134 NRDC v. WINTER
a. Statutory Background

As discussed earlier, NEPA requires a federal agency such

as the Navy to prepare a detailed EIS for all “major Federal

actions significantly affecting the quality of the human environment.” 42 U.S.C. § 4332(2)(C). However, if, as here, an

agency’s regulations do not categorically require the preparation of an EIS, then the agency must first prepare an EA to

determine whether the action will have a significant effect on

the environment. Nat’l Parks & Conservation Ass’n v. Babbitt, 241 F.3d 722, 730 (9th Cir. 2001); see 40 C.F.R.

§ 1501.4. If the action will significantly affect the environment, an EIS must be prepared, while if the project will have

only an insignificant effect, the agency issues a Finding of No

Significant Impact (FONSI). Ocean Advocates v. U.S. Army

Corps of Eng’rs, 402 F.3d 846, 864 (9th Cir. 2005); see 40

C.F.R. §§ 1501.3, 1501.4. 

[8] “An EIS must be prepared ‘if substantial questions are

raised as to whether a project . . . may cause significant degradation of some human environmental factor.’ ” Blue Mountains Biodiversity Project v. Blackwood, 161 F.3d 1208, 1212

(9th Cir. 1998) (quoting Idaho Sporting Congress v. Thomas,

137 F.3d 1146, 1149 (9th Cir. 1998)). Thus, a plaintiff need

not show that significant effects on the environment will in

fact occur; raising “substantial questions whether a project

may have a significant effect” on the environment is enough.

Id.; Idaho Sporting, 137 F.3d at 1150. 

NEPA’s procedural requirements mandate that an agency

take a “hard look” at the environmental consequences of its

actions. Earth Island II, 442 F.3d at 1159. NEPA is unique in

that it does not direct or require any particular substantive

action on the part of an agency. Its sole purpose is to require

that the agency be fully informed as to the environmental consequences of its actions, the mitigation measures available,

and the alternatives to its proposed action. Once fully

informed, the agency may make its own final rule or decision.

NRDC v. WINTER 2135
However, an agency may not avoid preparing an EIS by making conclusory assertions that an activity will have only an

insignificant impact on the environment. Ocean Advocates,

402 F.3d at 864. If an agency opts not to prepare an EIS, it

must put forth a “convincing statement of reasons” to explain

why a project’s impacts are insignificant. Blue Mountains,

161 F.3d at 1212 (quoting Save the Yaak Comm. v. Block, 840

F.2d 714, 717 (9th Cir. 1988)). 

[9] NEPA challenges are reviewed under the APA, which

provides that an agency action may be set aside if it is “arbitrary, capricious, an abuse of discretion, or otherwise not in

accordance with law[.]” 5 U.S.C. § 706(2)(A). The agency’s

decisions are “entitled to a presumption of regularity. But that

presumption is not to shield [the agency’s] action from a thorough, probing, in-depth review.” Citizens to Preserve Overton

Park, Inc. v. Volpe, 401 U.S. 402, 415 (1971) (citations omitted). Thus, in reviewing an agency’s decision not to prepare

an EIS, a court must “determine whether the agency has taken

a ‘hard look’ at the consequences of its actions, ‘based [its

decision] on a consideration of the relevant factors,’ and provided a ‘convincing statement of reasons to explain why a

project’s impacts are insignificant.’ ” Native Ecosystems

Council v. U.S. Forest Serv., 428 F.3d 1233, 1239 (9th Cir.

2005) (quoting Nat’l Parks & Conservation Ass’n, 241 F.3d

at 730). 

Agencies have wide discretion in assessing scientific evidence, but they “must ‘take a hard look at the issues and

respond[ ] to reasonable opposing viewpoints.’ ” Earth Island

II, 442 F.3d at 1160 (internal quotation omitted, brackets in

original). “ ‘When specialists express conflicting views, an

agency must have discretion to rely on the reasonable opinions of its own experts, even if a court may find contrary

views more persuasive. At the same time, courts must independently review the record in order to satisfy themselves that

the agency has made a reasoned decision based on its evaluation of the evidence.’ ” Id. (quoting Marsh v. Or. Nat. Res.

2136 NRDC v. WINTER
Council, 490 U.S. 360, 378 (1989)). “If an agency has failed

to make a reasoned decision based on an evaluation of the

evidence, we may properly conclude that an agency has acted

arbitrarily and capriciously.” Id. 

b. Substantial Questions about the Environmental

Impact of the Exercises

The district court found that NRDC had raised substantial

questions as to whether the SOCAL exercises would have a

significant impact on the environment. Jan. 3, 2008 Dist. Ct.

Order at 6-7. Accordingly, the court concluded that NRDC

had demonstrated probable success on the merits of its claim

that the Navy’s failure to prepare an EIS was arbitrary and

capricious and in violation of NEPA and the APA. Id. at 7.

The district court did not rely on an erroneous legal premise

or abuse its discretion in so concluding. 

[10] Initially, we repeat our observation that the Navy, by

seeking approval by CEQ of “alternative arrangements” pursuant to 40 C.F.R. § 1506.11, has effectively conceded that

the SOCAL exercises will have a significant impact on the

environment. See 40 C.F.R. § 1506.11. As the text of

§ 1506.11 indicates, the very purpose of the regulation is to

provide for the possibility of alternative arrangements where

emergency circumstances require the taking of an action

“with significant environmental impact” without observing

the requirements of NEPA. See id. The fact that the Navy

sought relief under § 1506.11 is evidence that the Navy recognizes that the SOCAL exercises have a “significant environmental impact.” 

Moreover, the fact that “[t]he Navy is currently evaluating

the environmental impact of MFA sonar training exercises

through its development of the SOCAL Range Complex Environmental Impact Statement,” Jan. 15, 2008 CEQ Letter at 2,

confirms that, at the very least, the Navy acknowledges that

substantial questions have been raised as to whether the

NRDC v. WINTER 2137
SOCAL exercises will have a significant impact on the environment. Accordingly, were we not to review the Navy’s EA,

we would have little difficulty concluding that the district

court did not rely on an erroneous legal premise or abuse its

discretion in determining that NRDC has demonstrated probable success on the merits of its NEPA claim. Our own review

of the EA leads us to the same conclusion.48

The Navy argues that the district court made a clearly erroneous assessment of the evidence of the effect of MFA sonar

on marine mammals in the waters of southern California. Specifically, the Navy asserts that the court misunderstood the

significance of the EA’s reference to the 548 predicted

instances of Level A harassments of beaked whales. The

Navy explains that it categorized predicted sonar exposures to

beaked whales as Level A harassments not because beaked

whales were expected to suffer such harassments but rather

because such categorization would allow the Navy to analyze

the potential impacts of MFA sonar on each beaked whale

species in greater detail than it would otherwise. 

We find no abuse of discretion in the district court’s rejection of the Navy’s argument. The Navy’s explanation for its

categorization of predicted sonar exposures to beaked whales

as Level A harassments finds no support in the EA, and counsel for the Navy was unable to explain at oral argument on

November 8, 2007, how classifying exposures as Level A

harassments would allow the Navy to better analyze the

impacts of MFA sonar on various species of beaked whales.

Rather, the EA makes clear that the Navy categorized the

expected exposures to beaked whales as Level A harassments

because it concluded, in light of recent beaked whale strandings linked to the use of MFA sonar, that beaked whales may

48The Navy does not reargue the merits of NRDC’s NEPA claim in its

current appeal brief. We therefore assume that the Navy’s current position

is the same as set forth in its brief filed with our court on September 14,

2007. 

2138 NRDC v. WINTER
be more sensitive to sonar exposures than other cetaceans.

Because the lack of data precluded the Navy from establishing separate impact thresholds for beaked whales, the Navy

decided that for beaked whales it would categorize exposures

as Level A harassments that would constitute Level B harassments for other cetaceans. 

The Navy’s decision to do so is supported by ample evidence indicating that beaked whales are particularly vulnerable to MFA sonar. The documented strandings of marine

mammals that have been linked to the use of MFA sonar

overwhelmingly involve beaked whales.49 Indeed, according

to the International Whaling Commission the evidence associating the use of MFA sonar with beaked whale strandings is

“very convincing” and “appears overwhelming.” Similarly, a

Navy-sponsored study found “completely convincing” the

evidence that MFA sonar had caused strandings of beaked

whales. 

Moreover, to the extent that a paucity of scientific data prevents the Navy from establishing meaningful impact thresholds for beaked whales, that is a reason to conduct further

research and prepare an EIS—not a reason to ignore the data

that does exist and proceed with the SOCAL exercises with49We reject the Navy’s argument that the district court erred by relying

on evidence not included in the Navy’s administrative record in reaching

its conclusion that NRDC had demonstrated probable success on the merits. While generally a district court’s review under the APA is limited to

the administrative record before the agency, it may consider evidence

beyond the administrative record in certain situations. See, e.g., Ranchers

Cattlemen Action v. USDA, 499 F.3d 1108, 1117 (9th Cir. 2007). The district court properly considered extra-record evidence here because the

Navy never submitted an administrative record to the district court despite

having had almost a year to do so since NRDC filed its complaint on

March 22, 2007. The Navy has not offered any valid explanation for why

it failed to submit an administrative record. We note that the Navy filed

a fourteen-volume record in the related litigation concerning the 2006

RIMPAC exercise only two days after NRDC filed its complaint in that

case. 

NRDC v. WINTER 2139
out adequate mitigation measures. As we explained in

National Parks: 

An agency must generally prepare an EIS if the environmental effects of a proposed agency action are

highly uncertain. Preparation of an EIS is mandated

where uncertainty may be resolved by further collection of data or where the collection of such data may

prevent speculation on potential . . . effects. The purpose of an EIS is to obviate the need for speculation

by insuring that available data are gathered and analyzed prior to the implementation of the proposed

action. 

Nat’l Parks & Conservation Ass’n, 241 F.3d at 732 (internal

citations and quotations omitted). 

The Navy also contends that the district court misunderstood the significance of the nearly 170,000 predicted Level

B harassments. First, the Navy argues that this number is an

overestimate resulting from conservative assumptions in its

model and from the fact that it does not take into account the

mitigation measures the Navy would employ. However, the

Navy stated in the EA that its prediction of the harm to marine

mammals was “consistent with the best available science.”

And while the Navy “assumed” that its prediction was an

overestimate, it acknowledged that the science was “incomplete,” which apparently precluded the Navy from even

approximating by how much it had overestimated the harm.

Likewise, the Navy made no attempt to approximate how

many Level B harassments its mitigation measures would prevent.50 Accordingly, we, like the Navy, must rely on the estimate of nearly 170,000 predicted Level B harassments. 

50The Navy has estimated that in the 2006 RIMPAC exercise, the

employed mitigation measures prevented approximately 100 marine mammals from being exposed to MFA sonar. Even ignoring the fact that the

mitigation measures employed in the 2006 RIMPAC exercise were more

2140 NRDC v. WINTER
Second, the Navy argues that most of the predicted Level

B harassments are below the threshold for causing temporary

hearing loss and will induce only temporary behavioral

responses which can be as minor as causing an animal to

avoid the noise source. But according to the Navy’s own definition of Level B harassment, those temporary behavioral

responses are nevertheless profound, as they cause “disruption

of natural behavioral patterns . . . to a point where such

behaviors are abandoned or significantly altered.”

51 As the

NMFS’ Biological Opinion makes clear, such disruption of

natural behavioral patterns can be lethal for marine mammals.

While the EA also states that it is “highly unlikely” that

Level B harassments would cause disturbance to a point

where behavioral patterns are abandoned or significantly

altered, the EA provides no support for that statement and

fails to explain why those harassments are nevertheless classified as Level B under the EA’s own definition. The district

court did not abuse its discretion in determining that such a

conclusory statement does not dispense with the requirement

of preparing an EIS. See Ocean Advocates, 402 F.3d at 864

(“[An agency] cannot avoid preparing an EIS by making conclusory assertions that an activity will have only an insignificant impact on the environment.”). 

Next, the Navy argues that it was “entitled to rely” on the

stringent than those the Navy has agreed to employ in the SOCAL exercises, that estimate would suggest that in the fourteen SOCAL exercises

the mitigation measures would prevent only 1,400 exposures to marine

mammals (14 exercises x 100 prevented exposures). Accordingly, the estimate of 170,000 Level B harassments would hardly be diminished by the

Navy’s current mitigation measures. 

51The Navy derived this definition from the MMPA, 16 U.S.C.

§ 1362(18)(B)(ii), which was amended in 2003 to exclude from the definition those acts that disrupted natural behavioral patterns but not to the

point where the behaviors were abandoned or significantly altered. See

H.R. Rep. No. 99(I), 108th Cong. 1 Sess. 2003 (5/14/03). 

NRDC v. WINTER 2141
conclusion of the NMFS in its Biological Opinion, which the

district court held satisfied the NMFS’ statutory obligation,

see 16 U.S.C. § 1536(a)(2), that the SOCAL exercises were

not likely to jeopardize the continued existence of threatened

or endangered marine mammal species. But the NMFS opined

only on the effects of MFA sonar on six species of marine mammal,52 which do not include several rare or uncommon species

of marine mammal that are expected to be exposed to a significant number of sonar harassments.53 For example, the EA

predicts 436 Level A harassments of Cuvier’s beaked whales.

According to NOAA, as few as 1,121 Cuvier’s beaked whales

may exist in California, Oregon and Washington combined.

Likewise, the EA predicts 1,092 Level B harassments of bottlenose dolphins, of which only 5,271 may exist in the California Coastal and Offshore stocks. 

The Navy suggests that the test is whether the continued

existence of marine mammal species is jeopardized. This is

wrong. An agency action can have “significant effects” on the

environment short of threatened extinction. NEPA regulations

promulgated by CEQ provide that “significantly” has two

components: context and intensity. 40 C.F.R. § 1508.27. Context refers to the setting in which the proposed action takes

place, in this case the Southern California Operating Area.

See id. § 1508.27(a). Intensity means “the severity of impact.”

Id. § 1508.27(b). In considering the severity of the potential

52Those six species are the fin whale, humpback whale, sei whale,

sperm whale, and Guadalupe fur seal. 

53While in a recent memorandum—written well after the Navy prepared

its EA—the NMFS concluded that the Navy’s own mitigation measures

“will minimize the likelihood of beaked whales being caught in circumstances that characterize known strandings of beaked whales,” Jan. 9,

2008 Memorandum from NMFS to the Under Secretary of Commerce for

Oceans and Atmosphere at 3, the NMFS did not conclude that the Navy’s

measures would prevent direct physical injury (such as tissue damage) to

beaked whales. Indeed, the NMFS acknowledged that “the mechanism by

which MFA sonar appears to be injurious to beaked whales is poorly

understood.” Id. at 4. 

2142 NRDC v. WINTER
environmental impact, a reviewing agency may consider up to

ten factors to help inform the “significance” of a project,

including the degree to which the effects on the quality of the

human environment are likely to be “highly controversial”

and the degree to which the possible effects on the human

environment are “highly uncertain or involve unique or

unknown risks.” Id. §§ 1508.27(b)(4), (b)(5). We have held

that “one of these factors may be sufficient to require preparation of an EIS in appropriate circumstances.” Ocean Advocates, 402 F.3d at 865; see Ctr. for Biological Diversity v.

Nat’l Highway Traffic Safety Admin., 508 F.3d 508, 553 (9th

Cir. 2007); Nat’l Parks & Conservation Ass’n, 241 F.3d at

731. 

Notably, whether an agency action will jeopardize the continued existence of an endangered or threatened species is not

among these factors. See 40 C.F.R. § 1508.27(b). However,

the degree to which the action may “adversely affect” an

endangered or threatened species is. See id. § 1508.27(b)(9).

While the NMFS’ Biological Opinion concluded that the

SOCAL exercises were not likely to jeopardize the continued

existence of the six endangered species it studied, it nevertheless acknowledged that the exercises “may adversely affect”

those species. Thus, while the Navy was not required to disregard the NMFS’ “no jeopardy” opinion, see Envtl Prot. Info.

Ctr. v. U.S. Forest Serv., 451 F.3d 1005, 1012 (9th Cir. 2006),

the Biological Opinion by its own terms makes clear that the

SOCAL exercises may “significantly” affect the environment,

see Greater Yellowstone Coalition v. Flowers, 359 F.3d 1257,

1275-76 (10th Cir. 2004) (regarding as not determinative for

NEPA purposes the Fish and Wildlife Service’s “no jeopardy”

opinion as to bald eagles). 

The Navy further argues that its finding of no significant

impact was not arbitrary and capricious because no sonarinflicted injuries have been observed in the Southern California Operating Area in almost forty years of MFA sonar use

by the Navy. But as explained above, that fact has limited

NRDC v. WINTER 2143
probative value in establishing whether marine mammals will

in fact be harmed by the Navy’s use of MFA sonar. Exposure

to MFA sonar may physically and behaviorally harm marine

mammals even if it does not cause them to strand. And absent

stranding, such harm is difficult to observe. That is particularly true for the beaked whale—the marine mammal most

vulnerable to MFA sonar—in which a population decline of

50% over 15 years would go undetected as a decline at all in

90% of the beaked whale stocks. 

Finally, the Navy claims that the correlation between the

past marine mammal strandings and MFA sonar is irrelevant

because the combination of environmental conditions “found

at the locations of documented marine mammal stranding

incidents” is not present in the Southern California Operating

Area. But contrary to this claim, the EA indicates that the

Navy has studied only the stranding in the Bahamas in 2000

and not any of the other stranding events. 

Moreover, while the Navy’s study of the Bahamas stranding identified a combination of factors that contributed to the

whales’ injury—the presence of a strong surface duct, unusual

water bathymetry, intensive use of multiple sonar units over

an extended period of time, a constricted channel with limited

egress, and the presence of beaked whales that appear to be

sensitive to the frequencies produced by these sonars—the EA

provided no supporting data or analysis for its conclusion that

this combination of factors does not exist in the Southern California Operating Area. Thus, we find no abuse of discretion

in the district court’s conclusion that the Navy has failed to

provide the support for its conclusion that NEPA requires. See

40 C.F.R. § 1502.24. 

In addition, the Navy’s Bahamas study acknowledged that

combinations of factors different from the one present in the

Bahamas “may be more or less likely to cause strandings”

(emphasis added). Thus, even if the combination of factors

present in the Bahamas in fact does not exist in the Southern

2144 NRDC v. WINTER
California Operating Area, the combination of factors that

does exist may be even more likely to cause injury to marine

mammals. The EA does not explore that possibility. 

[11] In sum, the district court did not abuse its discretion

in concluding that NRDC raised substantial questions as to

whether the SOCAL exercises would have a significant

impact on the environment. All of the reasons stated in the EA

for why the Navy believed the SOCAL exercises would not

have the deleterious effect that the Navy’s own model predicted were cursory, unsupported by cited evidence, or unconvincing. Thus, we find ample support for the district court’s

conclusion that the Navy has not “articulate[d] a rational connection between the facts found and the conclusion[ ]

reached.” Earth Island II, 442 F.3d at 1156-57 (quoting Midwater Trawlers Co-op v. Envtl. Def. Ctr., 282 F.3d 710, 716

(9th Cir. 2002)). 

c. The Navy’s Mitigation Measures

The district court also concluded that NRDC had demonstrated probable success on the merits of its claim that the

Navy’s mitigation measures were inadequate to obviate the

need for preparing an EIS. Again, we find no reliance on an

erroneous legal premise and no abuse of discretion in the district court’s conclusion. 

[12] The Navy correctly points out that “[a]n agency’s

decision to forego issuing an EIS may be justified in some circumstances by the adoption of [mitigation] measures” and

that those measures, if significant, “need not completely compensate for adverse environmental impacts.” Nat’l Parks &

Conservation Ass’n, 241 F.3d at 733-34 (citations and internal

quotation marks omitted). However, we have also held that a

“perfunctory description” or “mere listing of mitigation measures, without supporting analytical data,” is insufficient to

support a finding of no significant impact. Okanogan Highlands Alliance v. Williams, 236 F.3d 468, 473 (9th Cir. 2000)

NRDC v. WINTER 2145
(citations and internal quotation marks omitted). We find no

reversible error in the district court’s conclusion that the

Navy’s list of proposed mitigation measures was precisely

such a perfunctory description devoid of supporting data. 

[13] The explanation contained in the EA as to why the

mitigation measures are effective is contained in four short

bullet points, stating that whales and dolphins spend extended

periods of time on the surface, have relatively short dive periods, tend to move in large groups (pods), and frequently come

to the surface and have a high level of activity there. Three of

those bullet points in effect state the same thing, namely that

whales and dolphins spend little time under water. This explanation is inadequate for several reasons. 

[14] First, the Navy’s explanation overlooks the fact that

beaked whales spend much of their time under water, surface

infrequently, and are generally difficult to detect. A study by

NMFS scientists observed that “beaked whales are always difficult to see when they are on the surface, spend most of their

time below the surface, and are found at low densities over

large areas.” Likewise, NRDC submitted a declaration by a

biologist who opines that visual monitoring by ship-based

lookouts would result in the detection of only 2% of beaked

whales in the Southern California Operating Area, in part

because of the speed at which Navy vessels travel. Declaration of Dr. Robin William Baird ¶ 6. 

[15] Second, the Navy’s explanation fails to address the

effectiveness of the Navy’s safety zones—the only measure

that directly reduces exposure of marine mammals to MFA

sonar. Specifically, the EA fails to explain why a safety zone

of only 1,000 yards is adequate, why reducing the sonar level

by 6dB and 10dB at the 1,000-yard and 500-yard marks,

respectively, is adequate, and why it is effective to halt MFA

sonar transmission altogether only at the 200-yard mark.54 The

54As stated earlier, the Navy has recently agreed to adopt safety zones

with radii of 1,000, 500 and 200 meters instead of 1,000, 500 and 200

2146 NRDC v. WINTER
Navy’s explanation also does not relate to the effectiveness of

the measure requiring passive sonar to be used to detect

sounds made by marine mammals. 

While the Navy claims in the EA that it is “very likely” that

lookouts would detect a group of common dolphins because

of “frequent surfacing” and group sizes of “over a thousand

animals,” it notably makes no such claims about Cuvier’s

beaked whales, Mesoplodont beaked whales or Ziphiid

beaked whales. Indeed, the EA acknowledged that Cuvier’s

beaked whales and Mesoplodont beaked whales exhibit a

range of dives lasting up to 87 minutes. 

Moreover, while the EA claims that it is “very likely” that

Baird’s beaked whales will be detected by lookouts, it states

nothing about the frequency with which those whales surface.

While it may be that, as the EA states, beaked whales are

large in size and travel in groups of between nine and thirteen

animals, those facts hardly prove the effectiveness of visual

surveillance measures considering that beaked whales generally come to the surface infrequently. 

We find further support for the district court’s conclusion

that the Navy’s mitigation measures did not obviate the need

to prepare an EIS in the fact that, as explained above, the

Navy refused to adopt several of the more aggressive mitigation measures recommended by the CCC, employed in the

2006 RIMPAC exercise, or imposed by the Department of

yards. However, the radius of the Navy’s outer safety zone is still half of

the radius recommended by the CCC, resulting in a safety zone that is

75% smaller than the one found necessary by the CCC. 

Notably, NRDC has submitted declarations by scientists who state that

sonar levels even below the Navy’s lowest impact threshold of 173 dB

may be fatal and that sonar sound can travel up to hundreds of miles under

water, which suggests that the Navy’s significantly smaller safety zones

are inadequate. See Parsons decl. ¶ 13, Weilgart decl. ¶ 10. 

NRDC v. WINTER 2147
Defense for non-RIMPAC exercises in 2006. Specifically, the

Navy refused to: 

• Expand the outer safety zone to 2 kilometers;55

• Reduce sonar power in conditions of low visibility or strong surface ducting; 

• Avoid training in areas known to have high concentrations of marine mammals or during the

gray whale’s migratory season; 

• Monitor for 30 minutes prior to commencement

of MFA sonar use; 

• Restrict operation of MFA sonar within 25 kilometers from the 200-meter isobath; 

• Restrict operation of MFA sonar within 12 nautical miles from the coast;56 and 

• Restrict operation of MFA sonar in choke points,

constricted channels, or canyon-like areas.57

55The Navy did not discuss this measure in its EA, let alone explain why

it would not be effective. In its “after action report” following the 2006

RIMPAC exercise, the Navy disposed of this mitigation measure simply

by declaring it “not prudent” and “without scientific merit.” 

56The Navy asserts on appeal that the SOCAL exercises will occur more

than twelve nautical miles from the mainland coastline, but concedes that

the exercises will occur within twelve nautical miles of Clemente Island,

which falls within the Southern California Operating Area. In its January

3, 2008 preliminary injunction order the district court required the Navy

to refrain from using MFA sonar within 12 nautical miles from the California coastline. Jan. 3, 2008 Dist. Ct. Order at 14. 

57The parties disagree as to whether there are any choke points in the

Southern California Operating Area. In its January 3, 2008 preliminary

injunction order the district court found that the Catalina Basin poses the

same concerns as a choke point: ingress and egress to the basin are

restricted and the area has a high density of marine mammals. Jan. 3, 2008

Dist. Ct. Order at 17. Accordingly, the district court ordered the Navy to

refrain from using MFA sonar in the Catalina Basin. Id. at 17-18. 

2148 NRDC v. WINTER
Notably, as to most of these measures the Navy does not

contest that they would be effective. While the Navy claims

that some of the measures would adversely affect its ability to

achieve the objectives of the exercises, that does not render

the measures the Navy has adopted adequate to avoid the

need for preparing an EIS. Indeed, the Navy states in its “after

action report” following the first three SOCAL exercises that

in future exercises it intends to incorporate data collection

necessary to address the question of how many marine mammals not observed by lookouts may have been exposed to

dangerous sonar levels, and will integrate additional monitoring tools and techniques. While the Navy’s intent is commendable, it implicitly acknowledges that its current

mitigation and data collection efforts are less than adequate.

[16] We conclude that the district court did not abuse its

discretion in determining that the Navy’s cursory explanation

in the EA for why its mitigation measures are effective does

not demonstrate that those measures “constitute an adequate

buffer against the negative impacts” that may result from the

SOCAL exercises. See Nat’l Parks & Conservation Ass’n,

241 F.3d at 734. Accordingly, we uphold the district court’s

conclusion that the Navy’s reliance on its incomplete mitigation plan in deciding not to prepare an EIS was likely arbitrary and capricious and affirm its determination that NRDC

has demonstrated probable success on the merits of its NEPA

claims. Cf. Wetlands Action Network v. U.S. Army Corps of

Eng’rs, 222 F.3d 1105, 1112 (9th Cir. 2000).58

58The district court also concluded that NRDC had demonstrated probable success on the merits of its claims that the Navy violated NEPA by

preparing an EA that failed to adequately consider reasonable alternatives

to its proposed action, see, e.g., Bob Marshall Alliance v. Hodel, 852 F.2d

1223, 1228 (9th Cir. 1998) (explaining that under NEPA federal agencies

must sufficiently study, develop, and describe alternatives as part of the

“environmental decisionmaking process”), as well as the cumulative

impacts of its actions, see, e.g., Klamath-Siskiyou Wildlands Ctr. v.

Bureau of Land Mgmt., 387 F.3d 989, 994 (9th Cir. 2004) (explaining that

an EA must provide a “useful analysis of the cumulative impacts of past,

NRDC v. WINTER 2149
B. Possibility of Irreparable Injury

In our November 13, 2007 order we affirmed the district

court’s conclusion that NRDC had met its burden of demonstrating the possibility of irreparable injury. NRDC, 508 F.3d

at 886. We now explain that decision. 

[17] As the district court noted, “[w]here, as here, plaintiffs

demonstrate a likelihood of prevailing on the merits of their

claims, injunctive relief is appropriate where there is a ‘possibility of irreparable harm.’ ” Jan. 3, 2008 Dist. Ct. Order at 12

(quoting Faith Ctr. Church Evangelistic Ministries v. Glover,

480 F.3d 891, 906 (9th Cir. 2007)). NRDC must show the

possibility of irreparable harm to its membership. See Friends

of the Earth, Inc. v. Laidlaw Environmental Services (TOC),

Inc., 528 U.S. 167, 180-81 (2000). After analyzing the “numerous scientific studies, declarations, reports, and other evidence submitted,” the district court concluded that NRDC had

established “to a near certainty” that use of MFA sonar in the

SOCAL exercises will cause irreparable harm to the environment and to NRDC’s membership. Jan. 3, 2008 Dist. Ct.

Order at 12. 

[18] The Navy argues that the harm resulting to the environment from the use of MFA sonar in the SOCAL exercises

is merely “speculative.” But the Navy’s own EA proves otherwise. The EA estimates that the use of MFA sonar in the

SOCAL exercises will result in 564 instances of physical

injury including permanent hearing loss (Level A harassment)

and nearly 170,000 behavioral disturbances (Level B harassment), more than 8,000 of which would also involve tempopresent, and future projects”). Jan. 3, 2008 Dist. Ct. Order at 8-10. We

decline to address this aspect of the district court’s order as we have

already concluded that the court did not abuse its discretion in finding that

NRDC has demonstrated probable success on the merits of its other NEPA

claims. 

2150 NRDC v. WINTER
rary hearing loss. As explained above, while the Navy

protests that these figures are overestimates resulting from its

conservative approach, the EA makes clear that the figures are

“consistent with the best available science.” Indeed, the

Navy’s failure to suggest by how much its figures overestimate the actual harm to marine mammals confirms that the

EA’s figures are the best available estimates. Those estimates,

in turn, contradict the Navy’s suggestion that the harm caused

by MFA sonar in the SOCAL exercises is merely speculative.

Moreover, while the record contains no evidence that

marine mammals have been harmed by the use of MFA sonar

in the Southern California Operating Area, the scientific consensus that MFA sonar may cause injury and death to marine

mammals combined with the evidence that such injury, absent

a stranding, is difficult to detect—especially in the case of the

vulnerable beaked whale—further disproves the suggestion

that the harm caused by MFA sonar in the SOCAL exercises

is merely speculative. 

The Navy also argues that its use of MFA sonar will cause

only temporary harm to marine mammals and therefore will

not result in irreparable injury. But the EA again undermines

the Navy’s argument. The EA’s estimate that 564 instances of

Level A harassment will occur demonstrates that the use of

MFA sonar will also cause permanent harm to marine mammals. Likewise, the EA’s own definition of Level B harassment indicates that the nearly 170,000 estimated instances of

such harassment may result in the outright abandonment of

important behaviors by marine mammals. 

Finally, the Navy argues that NRDC failed to meet its burden of demonstrating that marine mammals “will suffer irreparable injury at the species or stock-level.” For two reasons,

the Navy has not shown that the district court relied on an

erroneous legal premise or abused its discretion in rejecting

this argument. 

NRDC v. WINTER 2151
First, NRDC had only the burden of demonstrating the

“possibility of irreparable injury,” Freecycle Network, 505

F.3d at 902, not that irreparable injury “will” necessarily

occur. See Earth Island II, 442 F.3d at 1159 (holding that the

district court erred in requiring that the plaintiff show a “significant threat of irreparable injury” because that standard

imposes a higher burden of proof than the “mere possibility

of irreparable harm” standard). 

Second, the Navy has cited no support for the proposition

that NRDC was required to demonstrate the possibility of

irreparable injury at the species or stock-level. While the

Navy relies on Water Keeper Alliance v. Dep’t of Defense,

271 F.3d 21 (1st Cir. 2001), the court in that case only concluded that the district court did not abuse its discretion in

concluding that the “death of even a single member of an

endangered species” would be an insufficient basis for the

plaintiffs to demonstrate the possibility of irreparable injury.

See id. at 34. Here, the district court found that, according to

the Navy’s EA, the SOCAL exercises “will cause widespread

harm to nearly thirty species of marine mammals, including

five species of endangered species, and may cause permanent

injury and death.” January 3, 2008 Dist. Ct. Order at 12. 

In any event, even if NRDC were required to demonstrate

the possibility of irreparable injury at the species or stocklevel, it would have satisfied that requirement here. As discussed earlier, the EA predicts 436 Level A harassments of

Cuvier’s beaked whales, of which, according to NOAA, as

few as 1,121 may exist in California, Oregon and Washington

combined. Similarly, the EA predicts 1,092 Level B harassments of bottlenose dolphins, of which only 5,271 may exist

in the California Coastal and Offshore stocks. 

[19] Accordingly, we hold that the district court did not

rely on an erroneous legal premise or abuse its discretion in

concluding that NRDC has demonstrated the possibility of

irreparable injury. 

2152 NRDC v. WINTER
C. Balance of Hardships

[20] Having determined that the district court neither relied

on erroneous legal premises nor abused its discretion in determining that NRDC has demonstrated a strong likelihood of

success on the merits of its NEPA claim and the possibility

of irreparable injury, we turn to the “balance of hardships.”

See Freecycle Network, 505 F.3d at 902. The Supreme Court

has held that environmental injury, in addition to often being

permanent or of long duration, can seldom, by its nature, “be

adequately remedied by money damages”; therefore, “[i]f

such injury is sufficiently likely, . . . the balance of harms will

usually favor the issuance of an injunction to protect the environment.” Amoco Prod. Co. v. Vill. of Gambell, AK, 480 U.S.

531, 545 (1987). 

The Navy maintains, and the district court did not contest,

that its ability to train and certify its west-coast strike groups

for combat deployment is critical.59 The Navy argues that its

59For example, Captain Martin M. May states that “[m]odern, quiet submarines . . . pose the primary threat to the littorals, control of strategic

maritime choke points, transit through international straits, and protection

of sea lines of communication vital to international commerce.” May decl.

¶ 19. These submarines are “nearly undetectable to U.S. and allied naval

forces without the use of [MFA] sonar.” Id. at ¶ 20. Captain May also

asserts that “[s]onar operators and crews must train regularly and frequently to develop the skills necessary to master the art and processes of

identifying submarines in the complex subsurface environment[,]” and

that computer simulations are not adequate for teaching these skills. Id. at

¶ 22. Captain May maintains that if sonar use is enjoined, the Navy would

be unable to gauge a fleet’s ability to use active sonar. Id. at ¶ 26. 

Captain May also contends that “[t]he ranges that comprise the Southern California Operating Area make up a unique area in which strike

groups can meet all required training objectives at the same time. Id. at

¶ 25. Another significant factor is that many of the operating areas have

been surveyed and closely mirror the prospective operating environments

in many of the world’s ‘hot’ spots where U.S. Naval forces may be

required to fight.” Id. Training “in our own littorals . . . also build[s] proficiency and experience in our own waters should the enemy attempt to

interdict U.S. forces deploying to the area of conflict.” Id.

NRDC v. WINTER 2153
ability to engage in these critical activities is severely

degraded by: (1) the requirement that it shut down its use of

MFA sonar when a marine mammal is detected within 2,200

yards of a sonar-emitting source; and (2) the requirement that

it power down its sonar use by 6 dB (75%) when significant

surface ducting conditions are detected. Without proper training and certification, the Navy asserts that it will not be able

to deploy a sufficient number of combat-ready forces to provide for the national defense. 

The district court rejected the Navy’s argument that the balance of hardships tipped in its favor. It concluded that

although “the imposition of these mitigation measures will

require the Navy to alter and adapt the way it conducts antisubmarine warfare training—a substantial challenge,” the

measures would not preclude the Navy from effectively training and certifying forces for deployment to combat zones in

the western Pacific and the Middle East.60 Feb. 4, 2008 Dist.

Ct. Order. 

The gravity of the Navy’s asserted hardship requires that

we review the district court’s determination, as well as the

affidavits submitted by the Navy, with the utmost care. We

have done so here and, for the reasons set forth below, we

conclude that the district court did not abuse its discretion in

reaching its determination. 

We note that any negative impact on the Navy’s ability to

successfully conduct its exercises under the challenged miti60The district court crafted its mitigation order after carefully weighing

evidence submitted by the parties over a period of “longstanding involvement” with the matters at issue. It took into account the Navy’s need for

training in certain bathymetry and under certain conditions, and declined

to impose several of plaintiffs’ proposed “sweeping geographic exclusions” which would have precluded the Navy from training with MFA

sonar within 25 nautical miles of the coast, in waters shallower than 1,500

meters to the maximum extent possible, and in the Westfall seamount and

the Cortez and Tanner Banks. Jan. 3, 2008 Dist. Ct. Order at 13 n.6. 

2154 NRDC v. WINTER
gation measures is necessarily speculative because the Navy

has never before employed these measures in the context of

MFA sonar training.61 The speculative nature of the Navy’s

asserted harm is reflected in its own characterization of the

hardship; the Navy does not claim that the challenged measures will categorically preclude effective training and certification, but rather that they will give rise to an “unacceptable

risk” of such a result. Our task, then, is to determine, as best

we are able from the record before us, whether the district

court erred by giving insufficient weight to the Navy’s

asserted hardship or by resting its conclusions on clearly erroneous factual findings. 

In support of its assessment that the challenged measures

will significantly impair its training exercises, the Navy offers

the declarations of various high-ranking officers. For example, Admiral John Locklear explains that the 2,200 yard safety

zone will in “[his] opinion . . . have crippling implications on

Navy’s ability to conduct realistic pre-deployment [ASW]

training employing MFA sonar” and “will significantly

impact ASW training.” Locklear decl. ¶¶ 9, 13. The Chief of

Naval Operations refers to an unacceptable risk to strike

group certification posed by both the safety zone and surface

ducting measures. The judgment of these naval officers and,

in particular, that of the Chief of Naval Operations, who is

charged with the statutory responsibility under 10 U.S.C.

61The Navy has not represented that, if the challenged measures are

upheld, it will cease its training exercises. Further, the Navy acknowledged at oral argument on February 27, 2008, that it can certify strike

groups despite the inability to train in surface ducting conditions. We

therefore proceed under the assumption that the exercises will continue to

take place, thereby preserving the possibility of successful training and

certification of strike groups. Thus, the district court did not err in failing

to weigh the hardship to the Navy, and the public, that would result if the

Navy stopped training altogether. Rather, the district court did not abuse

its discretion and properly considered the hardship that would result if the

Navy were required to abide by the challenged mitigation measures during

its remaining exercises in 2008 and 2009. 

NRDC v. WINTER 2155
§ 5062 for organizing, training, and equipping the Navy, is

entitled to substantial deference. See Khalsa v. Weinberger,

779 F.2d 1393, 1400 n.4 (9th Cir. 1985) (“The degree of deference due to factual assertions by the military is proportionate to the need for the application of military experience,

judgment, and expertise in evaluating the assertion.”). 

Nevertheless, a court’s deference is not absolute, even

when a government agency claims a national security interest.

See, e.g., Campbell v. U.S. Dep’t of Justice, 164 F.3d 20, 30

(D.C. Cir. 1998) (“[D]eference is not equivalent to acquiescence . . . .”). The district court therefore did not abuse its discretion when it considered the Navy’s declarations along with

the evidence contained in the record as a whole. This evidence, much of it submitted by the Navy itself, supports the

district court’s conclusion that the challenged mitigation measures will not likely compromise the Navy’s ability to effectively train and certify its west-coast strike groups. We

address the evidence with respect to each of the challenged

mitigation measures in turn. 

1. The 2,200 Yard Shutdown Zone

We first consider the requirement that the Navy shut down

its use of MFA sonar when a marine mammal is detected

within 2,200 yards of a sonar-emitting source.62 Upon a careful review of the record, we find no clear error in the district

court’s factual finding that this measure would not compromise the Navy’s ability to train and certify its strike groups.

62Although our discussion supra addresses the evidence contained in the

record with respect to the likely impact that the increase in the safety

zone’s size will have on training and certification, the Navy also contests

this measure’s application to all sonar sources, including helicopter dipping sonar and sonobuoys which emit less powerful sonar waves. See, e.g.,

Locklear decl. ¶ 11. Despite the fact that the dipping sonar and sonobuoys

have lower energy source levels, they still operate at levels above those

shown to pose a danger to marine mammals. See, e.g., Parsons decl. ¶ 13.

Accordingly, the district court’s decision to include these sonar sources in

its mitigation measure was not an abuse of discretion. 

2156 NRDC v. WINTER
[21] The “after action reports” compiled by the Navy following eight prior COMPTUEX and JTFEX exercises in the

Southern California Operating Area undermine the Navy’s

assessment of the significance of the hardship that this mitigation measure would impose.63 The reports contain several relevant data points. First, the data reveal a relatively low

likelihood that a marine mammal will be sighted during a time

when the Navy’s MFA sonar is in use, thereby triggering

implementation of this mitigation measure. During two of the

eight exercises, no marine mammals were sighted while MFA

sonar was in use. In the remaining exercises, sightings rarely

occurred while MFA sonar was in use.64 In fact, over the

course of eight exercises lasting one or more weeks each, the

Navy observed marine mammals only 51 times while using

MFA sonar, which represents less than 15% of all marine

mammal observations (345) during those exercises. Second,

the data show that the Navy shut down its MFA sonar twentyseven times over the course of its eight prior exercises. If the

district court’s mitigation measure had been in place, the

Navy would have had to shut down at most an additional

twenty-one times: an increase of only two to three shutdowns

per exercise.65 Moreover, of the twenty-one additional times

63During these exercises, the Navy’s preferred 1,000 yard safety zone

was implemented requiring a 6 dB power-down when a marine mammal

was detected within 500-1,000 yards, an additional 4 dB power-down

within 200 and 500 yards, and a mandatory shutdown within 200 yards.

We note that the first four of the eight exercises for which the record

contains “after action reports” were not part of the current SOCAL exercises. 

64The low likelihood of a sighting occurring while MFA sonar is being

used does not mean it is rare for marine mammals to be exposed to dangerous noise levels. Rather, two facts demonstrate that the number of

sightings does not equate to the number of mammals affected by an MFA

sonar event: (1) the presence of marine mammals is difficult to detect by

“sight” because many spend significant amounts of time submerged

underwater; and (2) sound travels long distances in water (in some cases

up to many hundreds of miles) creating the potential for adverse effects

beyond the range of sight. 

65The Navy argues that this mitigation measure will result in a five-fold

increase in the number of times it is required to shut down during training

NRDC v. WINTER 2157
that the Navy would have been required to shut down, in

eleven of these instances, the Navy powered down its sonar.

During these power-downs, the Navy’s detection capability

was significantly reduced. See, e.g., Bird decl. ¶ 49. Accordingly, if the district court’s injunction had been in place, the

Navy would have had to compromise detection capability

only approximately one more time per exercise. Third, the

“after action reports” do not establish any serious, negative

effects on operational impact from the smaller safety zone

imposed in the eight exercises.66 Because the broader safety

zone likely will not require significantly more shutdowns, the

exercises. The Navy arrives at this higher number by excluding from its

calculation shutdowns that occurred beyond the 200 yard mandatory shutdown zone. But this calculation fails to account for the Navy’s actual practice of shutting down sonar in a significant number of cases where marine

mammals were detected beyond 200 yards, including at distances as far as

3,100, 4,000, and 6,000 yards. In fact, the “after action reports” reveal that

of the twenty-seven times the Navy shut down MFA sonar, it did so fifteen

times when the observed marine mammals were outside the 200 yard mandatory shutdown zone and four times when the marine mammals were at

an “unknown” distance. 

There is no dispute that the Navy continued to certify its strike groups

throughout these exercises. The Navy defends its exclusion of any nonmandatory shutdowns in its count by claiming that any shutdowns that

occurred beyond the 200 yard range “likely occurred during tactically

insignificant times.” Locklear decl. ¶ 11. The record fails to support this

claim. The “after action reports” do not distinguish between shutdown

events in evaluating training impacts. Indeed, the very same language is

used to describe the loss of detection opportunities during all of the exercises, without regard to whether the shutdowns occurred within or beyond

200 yards. 

66Indeed, the “after action reports” contain only one instance in which

the Navy comments that its operation was actually affected by a safety

zone mitigation measure. See After Action Report for COMPTUEX 07-01

(19 November-19 December 2006) at 6. All the other reports state that the

impact of the safety zone measure was “not determinable in the reactions

of the particular units” and only speculate that “the proximity of a submarine in the vicinity meant there was a potential submarine detection opportunity missed by the exercise participants.” 

2158 NRDC v. WINTER
district court’s conclusion that this mitigation measure does

not pose a significant risk of rendering the Navy’s training

exercises ineffective is well-supported. We cannot, on this

record, find that the district court abused its discretion. 

In addition to data drawn from “after action reports,” the

record contains other evidence of the feasibility of mandatory

shutdown zones of this size, and even greater, during naval

training exercises. Indeed, the size of the district court’s

imposed shutdown zone was based on the CCC’s proposed

mitigation measure, which in turn was drawn from the Navy’s

own imposition of a 2,000 meter shutdown requirement when

it uses low-frequency active sonar.67 While the record does

not indicate whether low-frequency active sonar has the same

effect on marine mammals as MFA sonar, the Navy offers no

explanation as to why a 2,000 meter safety zone is feasible

during its operation of low-frequency active sonar but not

during its use of MFA sonar.68

67While we recognize that each Navy has unique operating requirements, the record shows that NATO imposes a 2,000 meter shutdown zone

when a marine mammal is detected—the same zone that the district

court’s preliminary injunction requires. The Australian Navy goes farther,

mandating a shutdown of activities if a marine mammal is detected within

4,000 yards of a sonar-emitting vessel. 

68To the contrary, in its initial submissions to the court, the Navy represented that “[p]rior to [the district court’s] requirement, the maximum

mandatory shutdown zone the Navy ever employed was 200 meters.” Jan.

15 Emergency Motion at 16 (emphasis added). This representation is

plainly contradicted by the record. In its most recent brief to the court, the

Navy clarified that, “Prior to this requirement, the maximum mandatory

shutdown zone ever employed for MFA sonar was 200 meters.” However,

the Navy still does not discuss nor defend its ability to implement a 2,000

meter safety zone in its low-frequency, but not in its mid-frequency, sonar

activities. 

NRDC v. WINTER 2159
2. The Requirement to Power-Down in Significant

Surface Ducting Conditions

[22] We next consider the requirement that the Navy

power-down its sonar use by 6 dB when significant surface

ducting conditions are detected. Although the Navy stresses

the importance of training in surface ducting conditions, it

admits—and the record confirms—that such conditions occur

relatively rarely in the southern California waters in which the

Navy has chosen to conduct its exercises. Indeed, the “after

action reports” from JTFEX and COMPTUEX exercises conducted in the Southern California Operating Area in 2006

show that significant surface ducting conditions were not

detected during any of those exercises. Yet despite the strike

groups’ inability to train under such conditions, the Navy certified them. The record, then, undermines the Navy’s contention that the district court’s mitigation measure regarding

surface ducting conditions will significantly impact its ability

to certify strike groups. 

[23] Thus, although the actual effect of the challenged mitigation measures on the exercises at issue is necessarily speculative, data from past Navy exercises and practices supports

the district court’s conclusion that the imposition of these

measures is not likely to prevent effective training and certification of strike groups. After a thorough review of this record,

we are not “left with the definite and firm conviction that a

mistake has been committed.” Sports Form, Inc., 686 F.2d at

752. To the contrary, there is significant evidence of the

Navy’s ability to successfully train and certify its strike

groups under the conditions imposed by the district court. We

therefore conclude that the district court did not abuse its discretion in ordering the Navy to comply with the challenged

mitigation measures. 

3. Balancing

As explained earlier, the scientific studies, declarations and

reports in the record confirm the district court’s determination

2160 NRDC v. WINTER
that irreparable harm to marine mammals will almost certainly result should the Navy be permitted to conduct its

remaining exercises without appropriate mitigation measures.

See, e.g., Bain decl. ¶ 14 (explaining that “the monitoring and

mitigation adopted by the Navy is insufficient to detect, much

less prevent, marine mammal injury and mortality”); Declaration of Dr. Thomas A. Jefferson decl. ¶ 4 (describing the link

between military sonar and the stranding and deaths of beaked

whales and other cetaceans). As the district court observed,

the 2,200 yard shutdown zone might protect marine mammals

from only “the harshest of sonar-related consequences.” Jan.

3, 2008 Dist. Ct. Order at 15. 

Further, as the district court noted, the exercises in southern

California are only a subset of the Navy’s training activities

involving active sonar.69 Id. at 12-13. NRDC submitted evidence that the Navy uses active sonar in hundreds of exercises

each year throughout the world. The evidence linking several

whale strandings to the Navy’s use of active sonar in training

exercises around the world further confirms that the Navy

trains in its use of active sonar in many different areas. 

[24] While we are mindful of the importance of protecting

national security, courts have often held, in the face of assertions of potential harm to military readiness, that the armed

forces must take precautionary measures to comply with the

law during its training. See, e.g., NRDC v. Evans, 364

F.Supp.2d 1083, 1143 (N.D. Cal. 2003) (“A tailored injunction reconciles the very compelling interests on both sides of

69Indeed, the EA shows that the Navy considered as alternatives conducting the exercises in other locations, including Alaska and Hawaii,

reducing the number of exercises, and using exercise simulation. While

the Navy’s EA provides reasonably detailed justifications for why the

Southern California Operating Area is uniquely suited to these exercises,

and demonstrates that the Navy would suffer a certain hardship if the considered alternatives were employed instead, the EA nonetheless shows the

Navy is still able to conduct its exercises in alternate locations, in reduced

number, or through simulation. 

NRDC v. WINTER 2161
this case, by enabling the Navy to continue to train with and

test [low-frequency active] sonar as it needs to do, while taking some additional measures to better protect against harm to

marine life.”); Makua v. Rumsfeld, 163 F.Supp.2d 1202, 1221

(D. Haw. 2001) (“Although the court recognizes the importance of national security and live-fire training, the potential

harm to the Army resulting from a brief preliminary injunction will not be significant.”). As in those cases, the district

court here carefully balanced the significant interests and

hardships at stake to ensure that the Navy could continue to

train without causing undue harm to the environment. We

review that balance to determine whether it rests on clearly

erroneous findings of fact. Having concluded that it does not,

we determine that the district court did not abuse its discretion

and therefore do not disturb its carefully considered injunction. 

We recognize that although the record indicates that the

Navy will be able to continue to train and certify strike groups

effectively despite the two challenged mitigation measures,

there remains the possibility that, when they are actually

implemented, it will be unable to do so. In light of the hardship that the Navy and the public would suffer should the

imposed measures actually result in an inability to train and

certify sufficient naval forces to provide for the national

defense, we conclude that, in the unlikely event that such a

situation arises, the Navy may return to the district court to

request relief on an emergency basis. 

D. Advancement of the Public Interest

There are two dimensions to the public interest in this case.

The public has an interest both in national security and in protection of the marine environment. The public interest with

respect to national security is the same as that discussed in our

consideration of the hardship the Navy would suffer if it were

unable to effectively train and certify its strike groups. The

public interest with respect to protection of the marine envi2162 NRDC v. WINTER
ronment is the same as that discussed in our consideration of

the irreparable injury NRDC would suffer if the SOCAL exercises were carried out in the absence of appropriate mitigation

measures. As our discussion makes clear, we conclude that

the district court did not rely on an erroneous legal premise

or abuse its discretion in analyzing either of these interests.

Accordingly, there is no need for any additional discussion of

the public interest. 

V. Conclusion 

The district court concluded that plaintiffs have met the

necessary burden of proof to demonstrate that preliminary

injunctive relief is appropriate. It held that plaintiffs have

shown a strong likelihood of success on the merits, as well as

the possibility of irreparable injury if relief is not granted. It

also held that plaintiffs have shown that the balance of hardships tips in their favor in light of the preliminary injunction’s

narrowly-tailored mitigation measures which provide that the

Navy’s SOCAL exercises may proceed as planned if conducted under circumstances that provide satisfactory safeguards for the protection of the environment. Finally, it held

that the public interest is advanced by a preliminary injunction that imposes adequate mitigation measures. In reaching

these conclusions, the district court neither relied on erroneous legal premises nor abused its discretion. We therefore

affirm the district court’s preliminary injunction. 

AFFIRMED. 

NRDC v. WINTER 2163