Nos. 99-36065
BRUCE BABBITT, Secretary, United
States Department of the Interior;
ROBERT STANTON, Director,                             D.C. No. CV-97-00456-JKS
National Park Service,                                   


Appeal from the United States District Court
for the District of Alaska
James K. Singleton, District Judge, Presiding

Argued and Submitted
July 31, 2000--Anchorage, Alaska

Filed February 23, 2001

Before: Dorothy W. Nelson, Stephen Reinhardt, and
Sidney R. Thomas, Circuit Judges.

Opinion by Judge Reinhardt




Catherine E. Stetson, Hogan & Hartson L.L.P., Washington,
D.C., for the plaintiff-appellant.

Sean H. Donahue, United States Department of Justice, Envi-
ronment and Natural Resources Division, Washington, D.C.,
for the defendants-appellees.

Cynthia Pickering Christianson, Anchorage, Alaska, for the



REINHARDT, Circuit Judge:

Glacier Bay National Park and Preserve is a place of "unri-
valed scenic and geological values associated with natural
landscapes" and "wildlife species of inestimable value to the
citizens." The Bay was proclaimed a national monument in
1925 and a national park in 1980. UNESCO designated Gla-
cier Bay an international biosphere reserve in 1986 and a
world heritage site in 1992.

Not surprisingly, many people wish to visit the park. As
there are no roads to Glacier Bay, most tourists arrive by boat.
To be more specific, most -- approximately 80% of the
park's visitors -- arrive on large, thousand-passenger cruise
ships. In 1996 the National Park Service (Parks Service) com-
menced implementation of a plan that increased the number
of times cruise ships could enter Glacier Bay each summer
season immediately by 30% and overall by 72% if certain
conditions were met. In its environmental assessments, the
Parks Service acknowledged that this plan would expose the
park's wildlife to increased multiple vessel encounters, noise
pollution, air pollution, and an increased risk of vessel colli-
sions and oil spills. The Parks Service also acknowledged that
it did not know how serious these dangers to the environment
were, or whether other dangers existed at all. Nevertheless,
declaring that its plan would have "no significant impact" on
the environment, the Parks Service put it into effect without
preparing an environmental impact statement (EIS).

The plaintiff National Park and Conservation Association
(NPCA), a nonprofit citizen organization, alleges that the

Parks Service's failure to prepare an EIS violated the National
Environmental Policy Act (NEPA), 42 U.S.C. S 4321 et seq.
It seeks an order requiring the Parks Service to prepare an EIS
and enjoining implementation of the plan pending its comple-
tion. The district court ruled that an EIS was not required
because the Parks Service had made its findings after ade-
quately "canvassing the existing knowledge base. " We
reverse the district court's ruling and remand with instructions
to enjoin the plan's increases in vessel traffic, including any
portion already put into effect, until the Parks Service has
completed an EIS.


There may be no place on Earth more spectacular than the
Glacier Bay. Located in the Alaskan panhandle, surrounded
by snow-capped mountain ranges, Glacier Bay extends sixty
miles inland and encompasses ten deep fjords, four of which
contain actively calving tidewater glaciers, and approximately
940 square miles of "pristine" marine waters. The air quality,
though fragile, is still unspoiled and permits those fortunate
enough to be visitors a crisp, clear view of the Bay with its
glacier faces as well as the opportunity to breathe the fresh
and invigorating air. The park is the habitat for an extraordi-
nary array of wildlife. On the land, pioneer plant communities
grow in areas recently exposed by receding glaciers. Moose,
wolves, and black and brown bears roam the park's spruce
and hemlock rain forest. Bald eagles, kittiwakes, murrelets,
and other seabirds nest along the shore; sea otters, harbor
seals, Steller sea lions, harbor and Dall's porpoises, minke,
killer, and humpback whales reside in the bay.

The Steller sea lion and the humpback whale, two of the
marine mammal species that inhabit Glacier Bay, are imper-
iled. The Steller sea lion was listed as a threatened species
under the Endangered Species Act (ESA), 16 U.S.C. 1531 et
seq., in 1990. The worldwide population of the species

declined by as much as 48% in the thirty years prior to 1992.1
Glacier Bay has several "haul-out" sites where hundreds of
Steller sea lions gather. The humpback whale, "the most
gamesome and lighthearted of all the whales," Herman Mel-
ville, Moby Dick, 123 (Harrison Hayford & Hershel Parker,
eds., W.W. Norton & Co. 1967) (1851), has been listed as an
endangered species since the enactment of the ESA in 1973.
Until a moratorium was instituted in 1965, commercial whal-
ing decimated the worldwide population of humpback whales.
Today only 10,000 to 12,000 remain.2 A subpopulation of
humpbacks spends the summer feeding season in southeast
Alaska, including the waters of Glacier Bay; other humpbacks
remain there throughout the year.

Watercraft -- cruise ships, tour boats, charter boats, and
private boats -- provide primary access to Glacier Bay's
attractions. Approximately 80% of the park's visitors are
cruise ship passengers. According to the Parks Service's envi-
ronmental assessment, the "key attraction of the visit to Gla-
cier Bay . . . [is] [t]he glaciers at the head of the West Arm
[of the Bay.] [They] are larger, more active, and considered
by the [cruise-ship] companies to offer a more spectacular expe-
rience."3 The ships linger at the glaciers from between fifteen
1 In 1997 the Steller sea lion was reclassified, for the worse, as an endan-
gered species. Greenpeace v. Nat'l Marine Fisheries Serv., 80 F. Supp. 2d
1137, 1139 (W.D. Wash. 2000).
2 In 1991 the U.S. National Marine Fisheries Service (Fisheries Service)
established a Final Recovery Plan for the humpback. The plan sets a long-
term goal of restoring 60% of the species's pre-whaling population (about
125,000) and a more immediate goal of maintaining and enhancing "cur-
rent or historical habitats used by humpback whales by reducing distur-
bance from human-produced underwater noise in important habitats when
humpback whales are present and [encouraging] government entities at all
levels to correct existing impacts on habitats of humpback whales."
3 To get there, cruise ships cross the entrance to the Bay and traverse its
western bank, both areas particularly frequented by humpback whales. See
Christine M. Gabriele, Population Characteristics of Humpback Whales in
Glacier Bay and Adjacent Waters 9 (1994).

minutes to an hour and provide a large, high viewing platform
from which to witness the crack and crash of the great ice
masses as they cast off huge shards of floating ice. Although
the ships' height permits an unobstructed view of the park's
geologic features, it limits close views of the wildlife and veg-
etation that form such a significant feature of the park.

Between 1968 and 1978, vessel traffic in Glacier Bay
increased dramatically. In 1978 the U.S. National Marine
Fisheries Service (Fisheries Service) produced a "biological
opinion" based on its studies of the humpback whale popula-
tion in Glacier Bay. The biological opinion expressed concern
over the "uncontrolled increase of vessel traffic " in the
whales' departure from the Bay during 1978 and 1979, and
cautioned that a continued increase in the amount of vessel
traffic "would likely jeopardize the continued existence of the
humpback whale population frequenting southeast Alaska."
The Fisheries Service recommended that the Parks Service
regulate the number of vessels entering Glacier Bay; restrict
vessels from approaching and pursuing whales; and conduct
studies on whale feeding behavior, the effect of vessels on
whale behavior, and the acoustic environment.4

The Parks Service soon thereafter promulgated regulations
governing the entry and activity of cruise ships and other ves-
sels in Glacier Bay. The regulations provided that only two
cruise ships could enter the bay each day, with a maximum of
89 cruise ship entries between June 1 and August 31. Smaller
boats, designated "private/pleasure craft," were limited to
twenty-one entries per day with a seasonal maximum of 538
4 The acoustic environment appears to be very important to humpback
whales. As many a schoolchild is aware, humpbacks produce a variety of
sounds, including moans, grunts, screams, and long complex "songs."
According to the Parks Service, "[p]ostulated functions for whale vocal-
izations include maintenance of distance among individuals, species and
individual recognition, maintenance of social organization, localization of
underwater topography, and contextual information about feeding, court-
ship, or alarm."

entries. Vessels were prohibited from intentionally position-
ing themselves within a quarter of a nautical mile of a whale
or attempting to pursue a whale. Within "designated whale
waters," vessels had to operate at a constant speed of ten
knots or less and follow a mid-channel course.

In 1983 the Fisheries Service issued a second biological
opinion, which concluded in part:

      [I]f the existing restrictions on the operation of ves-
      sels within the Bay were removed, the associated
      disturbance would be likely to jeopardize the contin-
      ued existence of the Southeast Alaska humpback
      whale stock. . . . [A]ny increase in vessel traffic in
      Glacier Bay probably will add to the level of traffic
      encountered by humpback whales in southeast
      Alaska, and thereby add to cumulative impacts to the
      humpback whale.

Nevertheless, the Fisheries Service opinion stated that a slight
increase in vessel traffic was tolerable, provided that the num-
ber of individual whales entering the bay did not fall below
the 1982 level and that appropriate corrective measures were
taken. Accordingly, in 1984 the Parks Service promulgated a
Vessel Management Plan (VMP) and regulations that pro-
vided for a 20% increase, in increments, in the previously
authorized vessel entry quotas. This overall increase -- allow-
ing for a total of 107 cruise ship entries per season -- was
fully realized in 1988.

In September 1992 the Parks Service completed an internal
draft of a new VMP that proposed to increase the then current
level of cruise ship entries in Glacier Bay by an additional
72%. On February 19, 1993, the Fisheries Service issued a
third biological opinion expressing its concern "about the
decline in humpback whale use of Glacier Bay," and stating
that there were "no studies to show that this decline is not due
to avoidance of vessel traffic." Although the Fisheries Service

did not oppose the draft VMP, it urged the Parks Service "to
take a conservative approach in all management actions that
may affect humpback whales" and to implement particular
research and monitoring programs.5 The Fisheries Service did
not find that the Parks Service's proposed action was "likely
to jeopardize the continued existence and recovery " of Steller
sea lions.

As mandated by NEPA, the Parks Service investigated
whether a substantial cruise-ship increase would significantly
affect the environment in Glacier Bay. See 42 U.S.C.
S 4332(2)(C); 40 C.F.R. S 1508.27. In May 1995 the Parks
Service issued a combined proposed VMP and environmental
assessment (EA). An EA is a document that, under NEPA, (1)
provides "sufficient evidence and analysis for determining
whether to prepare an environmental impact statement or a
finding of no significant impact;" (2) aids an agency's com-
pliance with NEPA when no EIS is necessary; and (3) facili-
tates preparation of an EIS when one is necessary. 40 C.F.R.
S 1508.9(a). An EA is a "less formal and less rigorous" docu-
ment than an EIS. Conner v. Burford, 848 F.2d 1441, 1446
(9th Cir. 1998).

The combined VMP/EA reported the existence of environ-
mental questions that went far beyond the potential impact on
the humpback whales. It also described and assessed six alter-
5 "Because there has not been systematic monitoring of humpback whale
prey density, distribution and type, and noise produced by vessels, it is
impossible to ascribe whale distribution shifts to one cause or another.
However, it is [the Fisheries Service's] opinion that for the next three sea-
sons (1993, 1994, and 1995), the levels of vessel use combined with vessel
operation requirements as described in the September 25, 1992, Vessel
Management Plan and environmental assessment are not likely to jeopar-
dize the continued existence of the North Pacific population of humpback
whales." This opinion did not consider the localized effects of the pro-
posed action on the portion of the North Pacific whale population that
actually uses Glacier Bay, nor did it address possible effects that were sig-
nificant but less than likely to jeopardize the population's continued exis-

native approaches for managing vessels in Glacier Bay, rang-
ing from Alternative Four's reduction in vessel traffic by
between 14% and 22%, to Alternative One's maintenance of
the status quo, to Alternative Five's increase of cruise ship
entries by 72%. Notwithstanding the environmental problems
it recognized, the Parks Service expressed its preference for
Alternative Five. This alternative maintained the limit of two
cruise ship entries per day, but increased the total number of
seasonal entries from 107 to 184.6 It did not increase seasonal
entries for other vessels.

The Parks Service conducted six public hearings on the
VMP. The Parks Service received approximately 450 com-
ments, approximately 85% of which opposed Alternative Five
and favored Alternative Four. The Sierra Club, the Alaska
Wildlife Alliance, and the plaintiff NPCA spoke out against
Alternative Five at the hearings, and submitted expert opinion
and evidence in opposition to the Parks Service's findings. On
March 20, 1996, the Parks Service announced its decision to
implement a modified version of Alternative Five as its new
VMP. Under this modified plan, the seasonal entry quota for
cruise ships would increase by 30% for 1996 and 1997, and
by as much as 72% thereafter if certain conditions were met.
Also, the entry quotas for charter boats and private/pleasure
craft would increase by 8% and 15%, respectively. An accom-
panying revised EA, titled "Impacts of the Modified Alterna-
tive," discussed the effects of the new VMP on threatened and
endangered marine mammals, other marine mammals, birds,
and the human environment, including air quality.

The revised EA included the following observations:

      - Steller sea lions using open water "would be sub-
6 The EA identifies the "season " as lasting from June 1 through August
31. The proposed increase permits vessel entries every day of the season.
Accordingly, under Alternative Five, there will be thirty-eight more days
of vessel traffic each season.

      ject to increased vessel traffic and its related distur-
      bance. Little is known about the effects of the

      - The increased vessel traffic would expose the har-
      bor seal, harbor porpoise, Dall's porpoise, humpback
      whale, killer whale, and minke whale to "increased
      levels of disturbance," causing the animals to expend
      energy reserves and possibly compromising "the sur-
      vival and reproduction of individual animals." In
      addition, "the potential for daily and seasonal expo-
      sure of humpback whales to underwater noise would
      increase." "The effect of increased levels of distur-
      bance" on these cetacean populations, it concluded,
      was "unknown."

      - Marine mammals "using open-water habitats
      would be subject to increased vessel traffic and its
      related disturbance. However, little is known about
      the effects of the disturbance." The risk of vessels
      colliding with marine mammals would increase,
      although "the degree of increase is unknown." Simi-
      larly, there would be an increased risk of ship colli-
      sions, other accidents, and associated fuel spills.
      "The rate of actual spills could increase, but the
      degree of increase in unknown."

      - "The degree to which disturbance and displace-
      ment would affect the humpback whale populations
      in Glacier Bay is unknown. Several mitigation mea-
      sures implemented under this alternative would
      reduce the risk of whale/vessel interactions and the
      level of potential effects on individual whales. The
      implementation of oil-spill response plans by the
      cruise ship industry could reduce oil spill risks to
      individual whales."

      - It was "unknown" whether populations of Marbled
      Murrelets and Kittlitz Murrelets would change under
      the VMP.

      - "The overall effect on bald eagle populations is

      - "It is unknown if waterfowl populations would
      change under this alternative."

Finally, the revised EA acknowledged that the increase in
cruise ship entries would "result in more violations of state air
quality standards," but stated that the "biological effects of
these air pollutants from stack emissions are unknown."

At the same time it released its revised VMP and EA, 7 the
Parks Service also released a proposed Finding of No Signifi-
cant Impact (FONSI). As its title suggests, a FONSI states the
reasons why an agency's proposed action will not have a sig-
nificant effect on the environment and, therefore, it believes
that the preparation of an EIS is unnecessary under NEPA.
See 40 C.F.R. S 1508.13. The Parks Service's Glacier Bay
FONSI stated, in relevant part:

      The [Parks Service] has determined that the modi-
      fied alternative [Five] . . . can be implemented with
      no significant adverse effect to natural and cultural
      resources as documented by the environmental
      assessment. Key environmental issues associated
      with the modified alternative include effects on
      marine mammals and birds from vessel disturbance
      and air quality degradation from cruise ship stack
      emissions. Some disturbance to these resources
      would be expected. However, the mitigation strate-
      gies included in this action would significantly
7 The revised VMP and EA will hereinafter be referred to simply as the
VMP and EA.

      reduce environmental effects resulting from vessel

The NPCA submitted objections to the VMP/EA and the pro-
posed FONSI on April 19, 1996. The Parks Service adopted
the VMP/EA and issued its FONSI and final regulations on
the plan on May 30. See 61 Fed. Reg. 27,008, codified at 16
C.F.R. 13.65(b).

On May 2, 1997, the NPCA filed suit against Secretary
Babbitt and Dennis J. Galvin, Acting Director of the Parks
Service. The NPCA requested declaratory and injunctive
relief requiring the Parks Service "to rescind the new VMP
and prohibiting any activities to be conducted pursuant to
these rules until such time as [the Parks Service has] complied
with NEPA by preparing an adequate EIS for use in evaluat-
ing the new VMP before reimplementing it." Holland Amer-
ica Line Westours, Inc. ("Westours"), one of the two major
cruise ship operators in Glacier Bay, intervened as a defen-
dant pursuant to Federal Rule of Civil Procedure 24(a).

The NPCA, the Parks Service, and Westours each filed
motions for summary judgment. On August 24, 1999, the dis-
trict court issued an order denying NPCA's motion, granting
the Parks Service's motion, and denying Westours's motion
as moot. The court observed that the EA made it "fairly clear
that interactions between whales and vessels might be seri-
ously disruptive to wildlife residing in the Park. " It also
acknowledged "that the effects cruise ship operations have on
Glacier Bay National Park and the animals that live there are
unknown, either before ship operations increased or since,"
and that the "Modified Alternative Description[EA] attached
to the FONSI contains a long list of uncertainties about the
potential effects of increased vessel traffic." While it pro-
posed that further studies be conducted, it determined that the
existence of the numerous uncertainties was not sufficient to
require an EIS. "The EA in this case," the district court wrote,
"thoroughly canvasses all existing information and recognizes

that theoretical harms might occur, but concludes that there is
no evidence suggesting that a significant risk exists that the
harms will occur." It concluded:

      [A] modest increase in the number of visitors may be
      allowed while the studies are commissioned and the
      existing data base increased with care taken through
      ameliorization [sic] to recognize and eliminate prob-
      lems as they arise.

The district court granted the Parks Service's cross-motion for
summary judgment and dismissed the case. The NPCA
appealed, and Westours cross-appealed.



A. Standard of Review

We review a district court's decision to grant or deny a
motion for summary judgment de novo. Metcalf v. Daley, 214
F.3d 1135, 1141 (9th Cir. 2000) (citation omitted). In review-
ing an agency's decision not to prepare an EIS under NEPA,
we employ an arbitrary and capricious standard, Blue Moun-
tains Biodiversity Project v. Blackwood, 161 F.3d 1208, 1211
(9th Cir. 1998), cert. denied, 527 U.S. 1003 (1999), that
requires us to 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," id., and provided
a "convincing statement of reasons to explain why a project's
impacts are insignificant." Metcalf, 214 F.3d at 1142.

B. Environmental Assessment

[1] NEPA requires that an Environmental Impact Statement
(EIS) be prepared for all "major Federal actions significantly
affecting the quality of the human environment." 42 U.S.C.A.

S 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 Environmental Assessment
(EA) to determine whether the action will have a significant
effect on the environment. See 40 C.F.R.S 1501.4; Salmon
River Concerned Citizens v. Robertson, 32 F.3d 1346, 1356
(9th Cir. 1994). If the EA establishes that the agency's action
"may have a significant effect upon the .. . environment, an
EIS must be prepared." Foundation for N. Am. Wild Sheep v.
United States Dep't of Agric., 681 F.2d 1172, 1178 (9th Cir.
1982) (emphasis added); see also Blue Mountains , 161 F.3d
at 1212. If not, the agency must issue a Finding of No Signifi-
cant Impact (FONSI), see Blue Mountains, 161 F.3d at 1212;
40 C.F.R. SS 1501.4, 1508.9, accompanied by" `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.

[2] Whether there may be a significant effect on the envi-
ronment requires consideration of two broad factors:"context
and intensity." See 40 C.F.R. S 1508.27; 42 U.S.C.
S 4332(2)(C); see also Sierra Club v. United States Forest
Serv., 843 F.2d 1190, 1193 (9th Cir. 1988). 8 Context simply
8 "Significantly" as used in NEPA requires considerations of both con-
text and intensity:

       (a) Context. This means that the significance of an action must
      be analyzed in several contexts such as society as a whole
      (human, national), the affected region, the affected interests, and
      the locality. Significance varies with the setting of the proposed
      action. For instance, in the case of a site-specific action, signifi-
      cance would usually depend upon the effects in the locale rather
      than in the world as a whole. Both short- and long-term effects
      are relevant.

       (b) Intensity. This refers to the severity of impact. Responsible
      officials must bear in mind that more than one agency may make
      decisions about partial aspects of a major action. The following
      should be considered in evaluating intensity:

delimits the scope of the agency's action, including the inter-
ests affected. Intensity relates to the degree to which the
       (1) Impacts that may be both beneficial and adverse. A signifi-
      cant effect may exist even if the Federal agency believes that on
      balance the effect will be beneficial.

       (2) The degree to which the proposed action affects public
      health or safety.

       (3) Unique characteristics of the geographic area such as prox-
      imity to historic or cultural resources, park lands, prime farm-
      lands, wetlands, wild and scenic rivers, or ecologically critical

       (4) The degree to which the effects on the quality of the
      human environment are likely to be highly controversial.

       (5) The degree to which the possible effects on the human
      environment are highly uncertain or involve unique or unknown
       (6) The degree to which the action may establish a precedent
      for future actions with significant effects or represents a decision
      in principle about a future consideration.

       (7) Whether the action is related to other actions with individ-
      ually insignificant but cumulatively significant impacts. Signifi-
      cance exists if it is reasonable to anticipate a cumulatively
      significant impact on the environment. Significance cannot be
      avoided by terming an action temporary or by breaking it down
      into small component parts.

       (8) The degree to which the action may adversely affect dis-
      tricts, sites, highways, structures, or objects listed in or eligible
      for listing in the National Register of Historic Places or may
      cause loss or destruction of significant scientific, cultural, or his-
      torical resources.

       (9) The degree to which the action may adversely affect an
      endangered or threatened species or its habitat that has been
      determined to be critical under the Endangered Species Act of

       (10) Whether the action threatens a violation of Federal, State,
      or local law or requirements imposed for the protection of the

40 C.F.R. S 1508.27.

agency action affects the locale and interests identified in the
context part of the inquiry. Here, the context is Glacier Bay
National Park, its natural setting, its variegated non-human
inhabitants, and its pure but fragile air quality; intensity must
be established in this case by using three of the standards enu-
merated in S 1508.27: (1) the unique characteristics of the
geographic area; (2) the degree to which VMP Alternative
Five's possible effects on the human environment are highly
uncertain; and (3) the degree of controversy surrounding those
possible effects. The unique characteristics of Glacier Bay are
undisputed and of overwhelming importance. Accordingly,
we next consider the agency's determination in light of the
degree of uncertainty manifested, and the degree of contro-
versy generated. Either of these factors may be sufficient to
require preparation of an EIS in appropriate circumstances.
Sierra Club, 843 F.2d at 1193, 1194; Blue Mountains, 161
F.3d at 1212-14. In the end, we conclude that the Parks Ser-
vice clearly erred and that the high degree of uncertainty and
the substantial controversy regarding the effects on the quality
of the environment each necessitates preparation of an EIS.

C. Uncertainty

[3] An agency must generally prepare an EIS if the envi-
ronmental effects of a proposed agency action are highly
uncertain. See Blue Mountains, 161 F.3d at 1213 ("significant
environmental impact" mandating preparation of an EIS
where "effects are `highly uncertain or involve unique or
unknown risks' ").9 Preparation of an EIS is mandated where
uncertainty may be resolved by further collection of data, see
id. at 1213-14 (lack of supporting data and cursory treatment
of environmental effects in EA does not support refusal to
9 Greenpeace Action v. Franklin , 14 F.3d 1324 (9th Cir. 1993), is not to
the contrary. There the court simply noted that the cases cited did "not
stand for the proposition that the existence of uncertainty mandates the
preparation of an impact statement." 14 F.3d at 1334 n.11. Blue Mountains
has since filled that gap. 161 F.3d at 1213-14.

produce EIS), or where the collection of such data may pre-
vent "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 imple-
mentation of the proposed action." Sierra Club, 843 F.2d at

[4] Here, scientific evidence presented in the Parks Ser-
vice's own studies revealed very definite environmental
effects. The uncertainty was over the intensity of those
effects. The FONSI reported increased daily and seasonal
exposure of humpback whales and other denizens of the Bay
to underwater noise (and predicted a range of adverse behav-
ioral responses), "traffic effects" (including increased risk of
collision, affecting whales, harbor seals, sea otters, murrelets,
and molting waterfowl), and increased risk of oil pollution for
all animal life in the Park. An increase in cruise ships would
also "result in more violations of state air quality standards for
cruise ship stack emissions."10 Among the specific effects set
forth in the VMP/EA upon which the FONSI was based were
that increased vessel entry into the Bay would: subject stellar
sea lions to additional disturbance; increase the escape pat-
terns of various types of whales; potentially increase mortality
rates and change the social patterns of the harbor seal; pre-
clude sea otters from colonizing the upper Bay; and increase
disturbance of feeding murrelets, other seabird nesting colo-
nies, and bald eagles.

[5] The EA describes the intensity or practical conse-
quences of these effects, individually and collectively, as "un-
known." See pages 2425-2427, supra . The uncertainty
10 The initial EA reported that"[t]he airsheds of the steep-walled fjords
of Glacier Bay are susceptible to visible stack emissions becoming trapped
by temperature inversions and light winds. . . .[T]he tolerance for air pol-
lution in Glacier Bay is extremely low." In a study conducted in 1986 and
1987, 25 of 77 cruise ships's emissions were over twice the permitted

manifested through the EA stems from two sources: an
absence of information about the practical effect of increased
traffic on the Bay and its inhabitants; and a failure to present
adequate proposals to offset environmental damage through
mitigation measures. The lack of data regarding the practical
effect of increased traffic, like the failure to investigate envi-
ronmental impacts in Blue Mountains, 161 F.3d at 1213,
undermines "[t]he [Parks Service's] EA . . . [which] is where
the [agency's] defense of its position must be found." Id. That
document states that "[l]ittle is known about the effects of the
[cruise ship] disturbance" on steller sea lions; "[t]he effect of
increased levels of disturbance" on Glacier Bay's cetacean
populations is "unknown"; and "the degree of increase [in oil
spills as a result of increased traffic] is unknown." It also
states that the effect of noise and air pollution on murrelets,
bald eagles, and waterfowls remains "unknown" because
unstudied. Moreover, the extent to which air pollution will
diminish the beauty and quality of the natural environment is
also unknown.11 The Parks Service's EA does, however,
establish both that such information may be obtainable and
that it would be of substantial assistance in the evaluation of
the environmental impact of the planned vessel increase. The
EA proposes a park research and monitoring program to "fill
information needs, and understand the effects of vessel traffic
on air quality, marine mammals [and] birds . .. to assist in the
prediction, assessment, and management of potential effects
on the human, marine, and coastal environments of Glacier
Bay resulting from human use of the environment with partic-
ular emphasis on traffic." That is precisely the information
and understanding that is required before a decision that may
have a significant adverse impact on the environment is made,
and precisely why an EIS must be prepared in this case.
11 The initial EA acknowledged, however, that the proposed increase in
vessel traffic "could significantly impair the visual and photographic scene
at the glacier faces in Tarr Inlet, the high point of a Glacier Bay cruise,
and elsewhere in the park."

The Parks Service proposes to increase the risk of harm to
the environment and then perform its studies. It has in fact
already implemented the first part of its VMP. This approach
has the process exactly backwards. See Sierra Club, 843 F.2d
at 1195. Before one brings about a potentially significant and
irreversible change to the environment, an EIS must be pre-
pared that sufficiently explores the intensity of the environ-
mental effects it acknowledges. A part of the preparation
process here could well be to conduct the studies that the Park
Service recognizes are needed. That might be done here by
performing the studies of the current vessel traffic and extrap-
olating or projecting the effects of the proposed increase.12
Ultimately, the Park Service may develop other means for
obtaining the information it currently lacks. The point is,
however, that the "hard look" must be taken before, not after,
the environmentally-threatening actions are put into effect.

[6] The Parks Service's lack of knowledge does not excuse
the preparation of an EIS; rather it requires the Parks Service
to do the necessary work to obtain it. In Blue Mountains, we
found that general statements about possible environmental
effects failed the "hard look" test required under NEPA. 161
F.3d at 1213. Here, the Parks Service's repeated generic state-
ment that the effects are unknown does not constitute the req-
12 With respect to the cruise ships, the addition of thirty-eight extra days
of cruising may simply require the service to determine the current effects
of vessel traffic, and extrapolate or project from that data the effects of
increased traffic, taking into account all available relevant information,
including technological change affecting the cruise ship-industry. It
appears that the impact of the other increases in vessel traffic may also be
determined by studying the effects of the current traffic rates. We do not
decide here, however, how the EIS should be conducted. That is for the
Park Service to determine initially in the context of the applicable statutes
and regulations. We intend only to observe that in this case, unlike some
others, an actual study can probably be conducted on the basis of existing
conditions and that it is not necessary to consider the intensity of the effect
of vessel traffic entirely in the abstract. There are practical consequences
resulting from the current level of traffic that may be studied and consid-
ered in the final report.

uisite "hard look" mandated by the statute if preparation of an
EIS is to be avoided. See id. (" `general statements about
"possible" effects and "some risk" do not constitute a "hard
look" absent a justification regarding why more definitive
information could not be provided' ") (citing Neighbors of
Cuddy Mountain v. United States Forest Serv., 137 F.3d 1372,
1380 (9th Cir. 1998)). The Park Service's statement of rea-
sons does not provide a convincing explanation as to why the
requisite information could not be obtained prior to placing
the VMP into effect. Id. In short, the information currently
provided by the Parks Service in its EA leaves us with the
firm impression that, absent successful mitigation measures,
there is a substantial possibility that the VMP will signifi-
cantly affect Glacier Bay Park, including the air, the water,
and the various species that inhabit the Park.

[7] The second source of uncertainty is the Parks Service's
ability to offset the environmental impact of the increase in
vessel traffic through its proposed mitigation measures. An
agency's decision to forego issuing an EIS may be justified in
some circumstances by the adoption of such measures. Wet-
lands Action Network v. United States Army Corps of Eng'rs,
222 F.3d 1105, 1121 (9th Cir. 2000); Friends of Payette v.
Horseshoe Bend Hydroelectric Co., 988 F.2d 989, 993 (9th
Cir. 1993). "If significant measures are taken to`mitigate the
project's effects, they need not completely compensate for
adverse environmental impacts.' " Wetlands Action Network,
222 F.3d at 1121 (quoting Friends of Payette, 988 F.2d at
993). While the agency is not required to develop a complete
mitigation plan detailing the "precise nature of the mitigation
measures," the proposed mitigation measures must be "devel-
oped to a reasonable degree." Id.13 A " `perfunctory descrip-
13 In Laguna Greenbelt, Inc. v. United States Dep't of Transp., 42 F.3d
517, 528 n.11 (9th Cir. 1994), the court held that "scientific uncertainties
in the mitigation measures" need not be discussed during the EIS discus-
sion period. Such uncertainties must be discussed, however, during the
EIS preparation period. 40 C.F.R. S 1502.22

tion,' " Okanogan Highlands Alliance v. Williams, 236 F.3d
468, 473 (9th Cir. 2000) (quoting Neighbors of Cuddy
Mountain, 137 F.3d at 1380), or " `mere listing' of mitigation
measures, without supporting analytical data," is insufficient
to support a finding of no significant impact. Id. (quoting
Idaho Sporting Congress v. Thomas, 137 F.3d 1146, 1151
(9th Cir. 1998)). In evaluating the sufficiency of mitigation
measures, we consider whether they constitute an adequate
buffer against the negative impacts that may result from the
authorized activity. Specifically, we examine whether the mit-
igation measures will render such impacts so minor as to not
warrant an EIS. See Greenpeace Action, 14 F.3d at 1332.

[8] There is a paucity of analytic data to support the Parks
Service's conclusion that the mitigation measures would be
adequate in light of the potential environmental harms. By
contrast, in Okanogan the Forest Service conducted computer
modeling to predict the quality and quantity of environmental
effects, discussed the monitoring measures to be put in place,
ranked the probable efficacy of the different measures,
detailed steps to achieve compliance should the measures fail,
and identified the environmental standards by which mitiga-
tion success could be measured. Id. at 473-75. Because the
Forest Service "considered extensively the potential effects
and mitigation processes," the court found that discussion of
the mitigation measures was adequate to constitute the con-
vincing statement of reasons to permit preparation of a
FONSI. Id. at 477 (emphasis omitted). In this case, however,
the Parks Service did not conduct a study of the anticipated
effects of the mitigation measures nor did it provide criteria
for an ongoing examination of them or for taking any needed
corrective action (except for the plan to conduct "studies").
As with the rest of its proposal, it planned to act first and
study later.

The Parks Service first described its proposed mitigation
measures in the initial EA. That document reflects the uncer-
tainty that exists as to whether the mitigation measures would

work: moreover, it is unclear from that document whether the
measures are sufficiently related to the effects they are
designed to cure. The Parks Service simply noted, for exam-
ple, that mitigation measures "could mitigate some potential
effects to humpbacks in concentrated whale-use areas";
"could reduce whale/vessel collisions and reduce the noise
emanating from the ships"; "[s]pecial-use-area closures and
restrictions implemented under . . . alternative[five] may off-
set some of the expected disturbance." Air pollution measures
"would be expected to contribute to a reduction in cruise ship
stack emissions over time." Further, the service stated that it:

      intends to institute a comprehensive research and
      monitoring program to fill informational needs and
      quantity the effects of vessel traffic on air quality,
      marine mammals, birds and visitor-use enjoyment.
      The monitoring program, developed within one year
      of the record of decision, will stipulate research and
      protection actions [Parks Service] will undertake to
      ensure that environmental effects do not exceed
      acceptable levels. . .

The final EA was similarly uncertain with respect to the
proposed measures' effects. It recognized that a 10-knot speed
restriction to offset the increased vessel traffic might disturb
the creatures in the park, but that "very little is known about
the effects of the disturbance." The EA also stated that the
increase in seasonal entries "could reduce whale/vessel colli-
sions and reduce the noise level emanating from the ships
. . . , [f]ollow-up research and monitoring will be essential to
define humpback whale use patterns in Glacier Bay resulting
from this alternative"; and that "requiring cruise ships to
implement oil-spill response plans could mitigate the effects
of oil spills." As for air pollution, "the magnitude of increased
violations would presumably be reduced over time. " There is
no indication, however, as to how long any such reduction
might take or how great a reduction might ultimately be
accomplished. In short, there is no evidence that the mitiga-

tion measures would significantly combat the mostly "un-
known" or inadequately known effects of the increase in
vessel traffic. The EA's speculative and conclusory state-
ments are insufficient to demonstrate that the mitigation mea-
sures would render the environmental impact so minor as to
not warrant an EIS. See Greenpeace Action, 14 F.3d at 1332.

It is instructive to contrast this case with Wetlands Action
Network. In that case, the court made clear that, though the
mitigation measures were underdeveloped, the imposition of
special conditions, enforced through a permit, and reviewed
by various other agencies ensured that the measures would be
enforced in a manner that properly reduced negative environ-
mental impact. See Wetlands Action Network, 222 F.3d at
1121. Here, there were no such special conditions applied to
the Parks Service or the tour boat operators in connection with
the measures designed to mitigate the effects of the proposed
increase in cruise ships. In fact, whether the mitigation mea-
sures are fully enforced or not, the EA reflects significant
uncertainty as to whether they could provide an adequate
buffer against the harmful effects of the plan. This is under-
standable in light of the fact that the extent of those harmful
effects is itself unknown, and that in such circumstance it is
particularly difficult to estimate the effects of mitigation mea-
sures. That fact, however, does not help make the measures
adequate for purposes of avoiding the preparation of an EIS
-- quite the contrary.

As with the question of the extent of the unremediated
injury that might otherwise occur, the question of the impact
of the proposed mitigation measures must be studied as part
of the preparation of an EIS rather than after the injury has
transpired. The fact that the agency plans to test the effect of
its mitigation measures does not relieve it of the obligation to
prepare an EIS prior to the time of the threatened environmen-
tal damage. Rather, the Parks Service's testing proposal
shows that the information necessary to determine the impact
of any mitigation measures, like the information relating to

the extent of the injurious effects, may well be obtainable
before any environmental injury occurs. The proposed mitiga-
tion studies thus argue in favor of preparing an EIS, not
against it.

The district court found that the agency's decision not to
prepare an EIS was justified because the uncertainty reflected
the existing state of knowledge. The passage of cruise ships
through Glacier Bay is not a new development, however.
Both the vessels' sailings and the dispute over the potential
environmental damage have existed for a substantial period of
time. No new scientific developments are required in order to
obtain the requisite information. The Parks Service itself pro-
poses to conduct studies which it anticipates may provide the
answers. We simply hold that, under these circumstances,
where significant environmental damage may occur to a trea-
sured natural resource, the studies must be conducted first, not

D. Controversy

The district court also found that NPCA had not made a
sufficient showing of controversy to require preparation of an
EIS. Again, we disagree.

[9] Agencies must prepare environmental impact state-
ments whenever a federal action is "controversial," that is,
when "substantial questions are raised as to whether a project
. . . may cause significant degradation of some human envi-
ronmental factor," Northwest Envtl. Def. Ctr. v. Bonneville
Power Admin., 117 F.3d 1520, 1539 (9th Cir. 1997) (quoting
LaFlamme v. FERC, 852 F.2d 389, 397 (9th Cir. 1988))
(Reinhardt, J., concurring in part and dissenting in part), or
there is "a substantial dispute [about] the size, nature, or effect
of the major Federal action." Blue Mountains , 161 F.3d at
1212 (citing Greenpeace Action, 14 F.3d at 1335; Sierra
Club, 843 F.2d at 1190). A substantial dispute exists when
evidence, raised prior to the preparation of an EIS or FONSI,

see Greenpeace Action, 14 F.3d at 1334 (holding that party
may not establish controversy post hoc, when at the time of
the agency's action no controversy existed), casts serious
doubt upon the reasonableness of an agency's conclusions.14
See Idaho Sporting Congress, 137 F.3d at 1150; Blue
Mountains, 161 F.3d at 1212. NEPA then places the burden
on the agency to come forward with a "well-reasoned expla-
nation" demonstrating why those responses disputing the
EA's conclusions "do not suffice to create a public contro-
versy based on potential environmental consequences."
LaFlamme, 852 F.2d at 401 (citing Jones v. Gordon, 792 F.2d
821, 829 (1986)).15 The term "well reasoned explanation" is
simply a less direct way of saying that the explanation must
be "convincing." See Metcalf, 214 F.3d at 1142.

[10] After publication of the initial EA, and before publica-
tion of the EA and FONSI, the Parks Service received 450
comments on the VMP, approximately 85% of which opposed
Alternative Five and favored Alternative Four. This volume
of negative comment is more than sufficient to meet the "out-
pouring of public protest" discussed in Greenpeace Action.16
14 Although a court should not take sides in a battle of the experts,
Greenpeace Action, 14 F.3d at 1333; see also Wetlands Action Network,
222 F.3d at 1120-21, it must decide whether the agency considered con-
flicting expert testimony in preparing its FONSI, and whether the agency's
methodology indicates that it took a hard look at the proposed action by
reasonably and fully informing itself of the appropriate facts. See Idaho
Sporting Congress, 137 F.3d at 1150 (precluding the agency from relying
on expert opinion in the absence of hard data).
15 Consensus among the parties over the proposed measures is ordinarily
sufficient to satisfy the agency's burden. See Greenpeace Action, 14 F.3d
1334 (holding that consensus among objecting parties before agency
declined to prepare EIS sufficient to rebut showing of controversy); Bon-
neville Power, 117 F.3d at 1536 (holding that where agency cooperated
with objecting parties, and alleviated most of those parties concerns,
agency need not prepare EIS). No such consensus existed here.
16 That case distinguished other showings of public controversy made in
cases such as Wild Sheep, 681 F.2d at 1175 and n.10, by requiring that any
"outpouring of public protest" be contemporaneous with the period for
commentating on the EA, and holding that a post hoc dispute was insuffi-
cient to establish the necessary type of controversy. Greenpeace Action,
14 F.3d at 1334. That is not the case here.

See 14 F.3d at 1334. More important, to the extent the com-
ments urged that the EA's analysis was incomplete, and the
mitigation uncertain, they cast substantial doubt on the ade-
quacy of the Parks Service's methodology and data. The dis-
pute between NPCA and the Parks Service thus goes beyond
a disagreement of qualified experts over the "reasoned con-
clusions" as to what the data reveal. See Greenpeace Action,
14 F.3d at 1335.17 Here, the agency's conclusions were not
reached by reasoned extrapolation from the data, rather the
data were simply insufficient. The Parks Service acknowl-
edged that an increase in vessel traffic would have an environ-
mental impact. The data, however, did not establish the
intensity of that impact, nor the efficacy of the mitigation
measures designed to offset that unquantified impact. NPCA
asserted that the effects on the environment would likely be
substantial. The Parks Service responded that the extent of the
effects was unknown. Therein lay the controversy. In its
response, the agency proposed to determine the extent of the
effects by implementing the VMP and studying its conse-
quences. As we have stated in Section I.C, the absence of cur-
rently available information does not excuse the Parks Service
from preparing an EIS when there is a reasonable possibility
that such information can be obtained in connection with the
preparatory process. The agency's response is therefore not
sufficient to resolve the controversy. Accordingly, the case
before us is controlled by Blue Mountains, Idaho Sporting
Congress, and Sierra Club; and Greenpeace Action is not to
the contrary. Here, preparation of an EIS is mandated by the
"controversy," as well as by the "uncertainty," factor of the
intensity provision. 40 C.F.R. S 1508.27(b).


[11] NPCA asks this court to "reverse the District Court
17 Where there is conflict in the data, or the evidence supports several
conflicting opinions, the agency may rely upon the opinion of its expert.
Wetlands Action Network, 222 F.3d at 1121.

and remand the case with instructions to enjoin further imple-
mentation of the 1996 Vessel Management Plan until a full
Environmental Impact Statement is prepared." To determine
whether injunctive relief is appropriate, "even in the context
of environmental litigation," we apply "the traditional balance
of harms analysis." Forest Conservation Council v. United
States Forest Serv., 66 F.3d 1489, 1496 (9th Cir. 1995) (cita-
tions omitted); see also Amoco Prod. Co. v. Village of Gam-
bell, 480 U.S. 531, 541, 542 (1987) (holding that unless
Congress directed otherwise, "a court must balance the com-
peting claims of injury" in determining whether injunctive
relief is appropriate). "Environmental injury, by its nature,
can seldom be adequately remedied by money damages and
is often permanent or at least of long duration, i.e., irrepara-
ble," Amoco Prod. Co., 480 U.S. at 545. When the "proposed
project may significantly degrade some human environmental
factor," injunctive relief is appropriate. Alaska Wilderness
Recreation & Tourism Assoc. v. Morrison, 67 F.3d 723, 732.
See also Sierra Club, 843 F.2d at 1195; Save the Yaak, 840
F.2d at 722.

[12] NPCA has made the requisite showing for injunctive
relief. As we concluded in Section I, an EIS is required. We
so held because of the significant adverse impact on the envi-
ronment that might result from the implementation of the
VMP. See Blue Mountains, 161 F.3d at 1216 (an EIS is
required of an agency in order that it explore, more thor-
oughly than an EA, the environmental consequences of a pro-
posed action whenever "substantial questions are raised as to
whether a project may cause significant [environmental] deg-
radation"). Where an EIS is required, allowing a potentially
environmentally damaging project to proceed prior to its prep-
aration runs contrary to the very purpose of the statutory require-
ment.18 Here, the Parks Service has already undertaken a 30%
18 We have recognized, nevertheless, that in "unusual circumstances" an
injunction may be withheld, or, more likely, limited in scope. See Forest

increase in cruise-ship traffic preliminary to a seventy-two
percent increase. The potential effects of its action extend
beyond the endangered marine mammal population to the rest
of the wildlife at Glacier Bay, as well as the Park's air quality.
Kittiwakes, murrelet, eagles, sea otters, seals, sea lions, por-
poises, and killer and minke whales, as well as the better
known humpbacks, are affected. Until an EIS is prepared and
the effects of increased vessel traffic on the inhabitants and air
quality of Glacier Bay are properly examined, there is a suffi-
cient possibility of environmental harm that the VMP may not
be implemented.

Westours argues that the damage to its business should be
considered when addressing injunctive relief, that its financial
losses outweigh the potential damage to the environment, and
that NPCA "is not entitled to an injunction against the 32 sea-
sonal cruise ship entries" that the Parks Service authorized for
the 2000-2004 seasons. As a general rule, only the federal
government may be a defendant in a NEPA action. Wetlands
Action Network, 222 F.3d at 1114. An exception may be made
in the remedial phase of a case where the contractual rights
of the applicant are affected by the proposed remedy. See
Forest Conservation Council, 66 F.3d at 1495. Here, Wes-
Conservation Council, 66 F.3d at 1496. Amoco Production Co. is not to
the contrary. There, the Supreme Court rejected a presumption of irrepara-
ble injury where an agency failed adequately to investigate the conse-
quences of its proposed action, see Amoco Prod. Co., 480 U.S. at 544-45:
it required courts to undertake the traditional "balance of harms" analysis.
Id. at 545. We have fully weighed the competing interests using our tradi-
tional equitable jurisdiction, and conclude that injunctive relief is appro-
priate. Finally, in Sierra Club v. Marsh, 872 F.2d 497 (1st Cir. 1989),
then-Circuit Judge Breyer held that, because NEPA is a purely procedural
statute, the requisite harm is the failure to follow the appropriate proce-
dures. See id. at 500 (because NEPA can do no more than require the
agency to produce and consider a proper EIS, the harm that NEPA intends
to prevent is imposed when a decision to which NEPA obligations attach
is made without the informed environmental consideration that NEPA
requires). Marsh also justifies injunctive relief in this case.

tours was permitted to intervene, and appears before us as a
party-defendant. Westours has asserted financial damages
premised upon its contracts of carriage. Its loss of anticipated
revenues, however, does not outweigh the potential irrepara-
ble damage to the environment. Moreover, neither Westours
nor those of its passengers who may be unable to view Gla-
cier Bay at the time they originally planned have cause to
claim surprise as a result of any injunction. The plaintiffs filed
their objections to the plan approximately five years ago and
just one year later sought an injunction. If the passengers who
booked cruises on any "excess" tours were not warned by
Westours of the pending litigation, their interests were not
well served by that company. Thus, while Westours has
standing to object to our grant of injunctive relief, its evidence
fails to tilt the balance of harms in its favor.

For the purposes of injunctive relief, we may admit evi-
dence not before the district court to show that an agency has
rectified a NEPA violation after the onset of legal proceed-
ings. See Friends of the Clearwater v. Dombeck , 222 F.3d
552, 560 (9th Cir. 2000). Here, Westours asks us to consider
evidence addressing one aspect of NPCA's complaint, the
humpback whale population. We will assume that such evi-
dence is admissible. Westour's evidence shows a short term
increase in the humpback whale population, but completely
fails to address the other environmental effects at issue here.
Nor does it address the deficiencies in the Parks Service's EA
and FONSI. Accordingly, Westours's evidence is insufficient
to dissuade us from granting injunctive relief.

Finally, we note that where the question of injunctive relief
"raise[s] intensely factual issues," the scope of the injunction
should be determined in the first instance by the district court.
See Alaska Wilderness, 67 F.3d at 732. Here, however, there
are no such intensely factual issues and the scope of the
injunction to which NPCA is entitled is quite plain. It is
appropriate, therefore, for us to decide the injunction question
on this appeal.

We direct the district court to enjoin the further increases
in vessel traffic, and to return traffic levels to their pre-1996
levels. We agree, however, with the Parks Service's conten-
tion that "the current vessel regulations are in important
respects more environmentally protective than the 1984 regu-
lations they replaced." The NPCA does not contend (and the
record would not support a finding) that the 1996 VMP's
establishment of protected "whale waters" in parts of Glacier
Bay or implementation of oil-spill response plans pose an
actual or potential threat to the environment. Accordingly,
there is no basis for enjoining that part of Alternative Five.
Our order is limited to the thirty to seventy-two percent
increase in the seasonal entry quota for cruise ships, and the
eight percent increase for charter boats and fifteen percent
increase for "private/pleasure" craft. All entry quotas shall be
returned to the levels preceding the introduction of Alterna-
tive Five. The other measures adopted by the Parks Service in
its VMP shall remain in effect, and will not be subject to the

Notwithstanding the above, we recognize that the issuance
of the mandate in this case may be delayed for some period
of time as a result of the en banc procedures that this court
follows, and that such delay may occur even if we ultimately
decide not to grant a rehearing en banc. We do not believe,
however, that a sufficient emergency exists to warrant our
ordering that the injunction become effective prior to the
completion of our customary process. Accordingly, we cannot
know in advance how close to the opening of this year's
cruising season the mandate will issue, or even whether issu-
ance will be delayed until after the season has already begun.
Nor can we determine how great may be the practical disrup-
tion that would occur were last minute cancellation of a sig-
nificant number of voyages required. Accordingly, we leave
it to the district court to decide upon the effective date of the
injunction it is ordered to issue, and, specifically, to decide in
its informed discretion, and on the basis of any evidence that
may be presented, whether the injunction should take effect

prior to the completion of this year's cruising season, some-
time this September.


Much of the briefing and argument in this appeal has
focused on the impact of the VMP on the imperilled hump-
back whale population. However, a variety of other non-
human inhabitants of the Park -- bald eagles, kittiwakes,
murrelets, sea otters, harbor seals, Steller sea lions, harbor and
Dall's porpoises, minke, and killer whales -- are, as the EA
reflects, affected, and the already fragile air quality is as well.
The existence of adverse effects is not uncertain. What is
uncertain is the extent of the likely environmental injury, and
the impact of the proposed mitigation measures. The Parks
Service's own experts, whose integrity the government com-
mended at oral argument, admitted both the likelihood of cer-
tain harms to the environment of Glacier Bay and their
uncertainty about the likelihood of other harms. In giving
insufficient respect to their experts' evaluation of harm,
declaring that no significant environmental effects were
likely, and implementing the vessel traffic increase without
complying with the requirements of NEPA, the Parks Ser-
vice's decision-makers made a "clear error of judgment."
Marsh v. Or. Natural Res. Council, 490 U.S. 360, 378 (1989).

Glacier Bay Park is too precious an ecosystem for the Parks
Service to ignore significant risks to its diverse inhabitants
and its fragile atmosphere. We reverse the decision below and
remand with instructions that the district court issue an
injunction enjoining the granting of permits to vessels pursu-
ant to the 1996 increase in vessel entry quotas pending the
Parks Service's completion of an EIS. Permits shall be limited
in number to those authorized prior to the issuance of the EA,
the VMP, and the FONSI. The district court shall provide in
its order for whatever specific actions it deems necessary to
ensure that the number of cruise ships and other vessels
authorized to enter Glacier Bay (pending completion of an

EIS) shall not exceed the number authorized prior to the 1996
increase. It shall have the discretion, however, to determine
the effective date of its injunction, including whether the
order shall be made effective prior to the completion of this
year's cruising season.