                                                 Volume 1 of 2

                   FOR PUBLICATION
  UNITED STATES COURT OF APPEALS
       FOR THE NINTH CIRCUIT

NAVAJO NATION; HAVASUPAI TRIBE;           
REX TILOUSI; DIANNA UQUALLA;
SIERRA CLUB; WHITE MOUNTAIN
APACHE NATION; YAVAPAI-APACHE
NATION; THE FLAGSTAFF ACTIVIST
NETWORK,
               Plaintiffs-Appellants,
                 and
HUALAPAI TRIBE; NORRIS NEZ; BILL
BUCKY PRESTON; HOPI TRIBE;                      No. 06-15371
CENTER FOR BIOLOGICAL DIVERSITY,                 D.C. Nos.
                                          
                            Plaintiffs,       CV-05-01824-PGR
                  v.                          CV-05-01914-PGR
UNITED STATES FOREST SERVICE;                 CV-05-01949-PGR
NORA RASURE, in her official                  CV-05-01966-PGR
capacity as Forest Supervisor,
Responsible Officer, Coconino
National Forest; HARV FORSGREN,
appeal deciding office, Regional
Forester, in his official capacity,
              Defendants-Appellees,
ARIZONA SNOWBOWL RESORT
LIMITED PARTNERSHIP,
    Defendant-intervenor-Appellee.
                                          



                               2829
2830                 NAVAJO NATION v. USFS



NAVAJO NATION; HUALAPAI TRIBE;            
NORRIS NEZ; BILL BUCKY PRESTON;
HAVASUPAI TRIBE; REX TILOUSI;
DIANNA UQUALLA; SIERRA CLUB;
WHITE MOUNTAIN APACHE NATION;
YAVAPAI-APACHE NATION; CENTER
FOR BIOLOGICAL DIVERSITY; THE
FLAGSTAFF ACTIVIST NETWORK,
                            Plaintiffs,
                 and                            No. 06-15436
HOPI TRIBE,                                      D.C. Nos.
                                          
                 Plaintiffs-Appellant,        CV-05-01824-PGR
                  v.                          CV-05-01914-PGR
UNITED STATES FOREST SERVICE;                 CV-05-01949-PGR
NORA RASURE, in her official                  CV-05-01966-PGR
capacity as Forest Supervisor,
Responsible Officer, Coconino
National Forest; HARV FORSGREN,
appeal deciding office, Regional
Forester, in his official capacity,
              Defendants-Appellees,
ARIZONA SNOWBOWL RESORT
LIMITED PARTNERSHIP,
    Defendant-intervenor-Appellee.
                                          
                     NAVAJO NATION v. USFS                      2831



HUALAPAI TRIBE; NORRIS NEZ; BILL          
BUCKY PRESTON,
               Plaintiffs-Appellants,
                  v.
                                                 No. 06-15455
UNITED STATES FOREST SERVICE;
NORA RASURE, in her official                      D.C. No.
                                               CV-05-01824-PGR
capacity as Forest Supervisor,
Responsible Officer, Coconino                     OPINION
National Forest; HARV FORSGREN,
appeal deciding office, Regional
Forester, in his official capacity,
              Defendants-Appellees.
                                          
         Appeal from the United States District Court
                  for the District of Arizona
         Paul G. Rosenblatt, District Judge, Presiding

                  Argued and Submitted
       September 14, 2006—San Francisco, California

                      Filed March 12, 2007

  Before: William A. Fletcher and Johnnie B. Rawlinson,
 Circuit Judges, and Thelton E. Henderson,* District Judge.

            Opinion by Judge William A. Fletcher




  *The Honorable Thelton E. Henderson, Senior United States District
Judge for the Northern District of California, sitting by designation.
2836               NAVAJO NATION v. USFS


                        COUNSEL

Howard M. Shanker, Tempe, Arizona; William Curtis
Zukosky, DNA People’s Legal Services, Flagstaff, Arizona;
Terence M. Gurley, DNA People’s Legal Services, Window
Rock, Arizona; Laura Lynn Berglan, DNA People’s Legal
Services, Tuba City, Arizona; Anthony S. Canty, Lynelle
Kym Hartway, The Hopi Tribe, Kykotsmovi, Arizona, for the
appellants.

Rachael Dougan, Lane McFadden, United States Department
of Justice, Environment & Natural Resources Division, Wash-
ington, D.C.; Janice M. Schneider, Bruce Babbitt, Latham &
Watkins, Washington, D.C.; Philip A. Robbins, Paul G. John-
son, Jennings Strouss & Salmon, Phoenix, Arizona, for the
appellees.


                         OPINION

W. FLETCHER, Circuit Judge:

   The San Francisco Peaks in the Coconino National Forest
in northern Arizona have long-standing religious significance
to numerous Indian tribes of the American Southwest. The
Arizona Snowbowl is a ski area on Humphrey’s Peak, the
highest and most religiously significant of the San Francisco
                    NAVAJO NATION v. USFS                   2837
Peaks. After preparing an Environmental Impact Statement,
the United States Forest Service approved a proposed expan-
sion of the Snowbowl’s facilities. One component of the
expansion would enable the Snowbowl to make artificial
snow from recycled sewage effluent. Plaintiffs challenged the
Forest Service’s approval of the expansion under the Reli-
gious Freedom Restoration Act (“RFRA”), 42 U.S.C.
§§ 2000bb et seq., the National Environmental Protection Act
(“NEPA”), 42 U.S.C. §§ 4321 et seq., and the National His-
toric Preservation Act (“NHPA”), 16 U.S.C. §§ 470 et seq.

   After a bench trial, the district court held that the proposed
expansion did not violate RFRA. Navajo Nation v. U.S. For-
est Serv., 408 F. Supp. 2d 866, 907 (D. Ariz. 2006). At the
same time, the district court granted summary judgment to the
defendants on the plaintiffs’ NEPA and NHPA claims. Id. at
872-80. This appeal followed as to all three claims.

   Plaintiffs-appellants are the Navajo Nation, the Hopi Tribe,
the Havasupai Tribe, the Hualapai Tribe, the Yavapai-Apache
Nation, the White Mountain Apache Nation, Bill Bucky Pres-
ton (of the Hopi Tribe), Norris Nez (of the Navajo Nation),
Rex Tilousi (of the Havasupai Tribe), Dianna Uqualla (of the
Havasupai Tribe), the Sierra Club, the Center for Biological
Diversity, and the Flagstaff Activist Network. Defendants-
appellees are the United States Forest Service; Nora Rasure,
the Forest Supervisor; Harv Forsgren, the Regional Forester;
and intervenor Arizona Snowbowl Resort Limited Partnership
(“ASR”), the owner of the Snowbowl.

   We reverse the decision of the district court in part. We
hold that the Forest Service’s approval of the Snowbowl’s use
of recycled sewage effluent to make artificial snow on the San
Francisco Peaks violates RFRA, and that in one respect the
Final Environmental Impact Statement prepared in this case
does not comply with NEPA. We affirm the grant of summary
judgment to Appellees on four of Appellants’ five NEPA
claims and their NHPA claim.
2838                NAVAJO NATION v. USFS
                        I.   Background

   Humphrey’s Peak, Agassiz Peak, Doyle Peak, and Fremont
Peak form a single large mountain commonly known as the
San Francisco Peaks, or simply the Peaks. The Peaks tower
over the desert landscape of the Colorado Plateau in northern
Arizona. At 12,633 feet, Humphrey’s Peak is the highest point
in the state. The Peaks are located within the 1.8 million acres
of the Coconino National Forest.

   In 1984, Congress designated 18,960 acres of the Peaks as
the Kachina Peaks Wilderness. Arizona Wilderness Act of
1984, Pub. L. No. 98-406, § 101(a)(22), 98 Stat. 1485. The
Forest Service has identified the Peaks as eligible for inclu-
sion in the National Register of Historic Places and as a “tra-
ditional cultural property.” A traditional cultural property is
one “associat[ed] with cultural practices or beliefs of a living
community that (a) are rooted in that community’s history,
and (b) are important in maintaining the continuing cultural
identity of the community.” National Register Bulletin 38:
Guidelines for Evaluating and Documenting Traditional Cul-
tural Properties (rev. ed. 1998), available at http://
www.cr.nps.gov/nr/publications/bulletins/nrb38/.

   The Forest Service has described the Peaks as “a landmark
upon the horizon, as viewed from the traditional or ancestral
lands of the Hopi, Zuni, Acoma, Navajo, Apache, Yavapai,
Hualapai, Havasupai, and Paiute.” The Service has acknowl-
edged that the Peaks are sacred to at least thirteen formally
recognized Indian tribes, and that this religious significance is
of centuries’ duration. Though there are differences among
these tribes’ religious beliefs and practices associated with the
Peaks, there are important commonalities. As the Service has
noted, many of these tribes share beliefs that water, soil,
plants, and animals from the Peaks have spiritual and medici-
nal properties; that the Peaks and everything on them form an
indivisible living entity; that the Peaks are home to deities and
other spirit beings; that tribal members can communicate with
                   NAVAJO NATION v. USFS                  2839
higher powers through prayers and songs focused on the
Peaks; and that the tribes have a duty to protect the Peaks.

   Organized skiing has existed at the Arizona Snowbowl
since 1938. The original lodge was destroyed by fire in 1952.
A replacement lodge was built in 1956. A poma lift was
installed in 1958, and a chair lift was installed in 1962. In
1977, the then-owner of the Snowbowl requested authoriza-
tion to clear 120 acres of new ski runs and to do additional
development. In 1979, after preparing an Environmental
Impact Statement, the Forest Service authorized the clearing
of 50 of the 120 requested acres, the construction of a new
lodge, and some other development. An association of Navajo
medicine men, the Hopi tribe, and two nearby ranch owners
brought suit under, inter alia, the Free Exercise Clause of the
First Amendment and NEPA. The D.C. Circuit upheld the
Forest Service’s decision. Wilson v. Block, 708 F.2d 735
(D.C. Cir. 1983).

   The Snowbowl has always depended on natural snowfall.
In dry years, the operating season is short, with few skiable
days and few skiers. The driest year in recent memory was
2001-02, when there were 87 inches of snow, 4 skiable days,
and 2,857 skiers. Another dry year was 1995-96, when there
were 113 inches of snow, 25 skiable days, and 20,312 skiers.
By contrast, in wet years, there are many skiable days and
many skiers. For example, in 1991-92, there were 360 inches
of snow, 134 skiable days, and 173,000 skiers; in 1992-93,
there were 460 inches of snow, 130 skiable days, and 180,062
skiers; in 1997-98, there were 330 inches of snow, 115 skiable
days, and 173,862 skiers; and in 2004-05, there were 460
inches of snow, 139 skiable days, and 191,317 skiers.

   ASR, the current owner, purchased the Snowbowl in 1992
for $4 million. In September 2002, ASR submitted a facilities
improvement proposal to the Forest Service. In February
2004, the Forest Service issued a Draft Environmental Impact
Statement. A year later, in February 2005, the Forest Service
2840                NAVAJO NATION v. USFS
issued a Final Environmental Impact Statement (“FEIS”) and
Record of Decision (“ROD”). The ROD approved “Alterna-
tive Two” of the FEIS, the alternative preferred by the Snow-
bowl. Under Alternative Two, a number of changes were
proposed, including: an area for snow play and snow tubing
would be developed; a new high-speed ski lift would be
added; three existing lifts would be relocated and upgraded;
66 new acres of skiable terrain would be developed; 50 acres
of trails would be re-contoured; a three-acre beginner’s area
would be re-contoured and developed; an existing lodge
would be upgraded; and a new lodge would be built.

   Alternative Two also included a proposal to make artificial
snow using treated sewage effluent. Treated sewage effluent
is wastewater discharged by households, businesses, and
industry that has been treated for certain kinds of reuse. Under
Alternative Two, the City of Flagstaff would provide the
Snowbowl with up to 1.5 million gallons per day of its treated
sewage effluent from November through February. A new
14.8-mile pipeline would be built between Flagstaff and the
Snowbowl to carry the treated effluent. At the beginning of
the ski season, during November and December, the Snow-
bowl would cover 205.3 acres of Humphrey’s Peak with arti-
ficial snow to build a base layer. The Snowbowl would then
make additional artificial snow as necessary during the rest of
the season, depending on the amount of natural snow.

                  II.   Standards of Review

   Following a bench trial, we review the district court’s con-
clusions of law de novo and its findings of fact for clear error.
Lentini v. Cal. Ctr. for the Arts, 370 F.3d 837, 843 (9th Cir.
2004).

   We review de novo a grant of summary judgment. Muckle-
shoot Indian Tribe v. U.S. Forest Serv., 177 F.3d 800, 804
(9th Cir. 1999). Appellants bring their NEPA and NHPA
claims under the Administrative Procedure Act (“APA”),
                     NAVAJO NATION v. USFS                    2841
which provides that courts shall “hold unlawful and set aside
agency action, findings, and conclusions of law” that are
either “arbitrary, capricious, an abuse of discretion, or other-
wise not in accordance with law,” or “without observance of
procedure required by law.” 5 U.S.C. § 706(2)(A), (D).

           III.   Religious Freedom Restoration Act

   [1] Under the Religious Freedom Restoration Act of 1993
(“RFRA”), the federal government may not “substantially
burden a person’s exercise of religion even if the burden
results from a rule of general applicability, except as provided
in subsection (b).” 42 U.S.C. § 2000bb-1(a). “Exercise of reli-
gion” is defined to include “any exercise of religion, whether
or not compelled by, or central to, a system of religious
belief.” 42 U.S.C. §§ 2000bb-2(4), 2000cc-5(7)(A); see also
id. § 2000cc-5(7)(B) (further specifying that “[t]he use, build-
ing, or conversion of real property for the purpose of religious
exercise shall be considered to be religious exercise”). Sub-
section (b) of § 2000bb-1 qualifies the ban on substantially
burdening the free exercise of religion. It provides, “Govern-
ment may substantially burden a person’s exercise of religion
only if it demonstrates that application of the burden to the
person — (1) is in furtherance of a compelling governmental
interest; and (2) is the least restrictive means of furthering that
compelling governmental interest.”

   These provisions of RFRA were prompted by two Supreme
Court decisions. RFRA was originally adopted in response to
the Court’s decision in Employment Division, Department of
Human Resources of Oregon v. Smith, 494 U.S. 872 (1990).
In Smith, an Oregon statute denied unemployment benefits to
drug users, including Indians who used peyote in religious
ceremonies. Id. at 890. The Court held that the First Amend-
ment’s Free Exercise Clause does not prohibit burdens on
religious practices if they are imposed by laws of general
applicability, such as the Oregon statute. Characterizing its
prior cases striking down generally applicable laws as “hy-
2842                NAVAJO NATION v. USFS
brid” decisions invoking multiple constitutional interests, the
Court refused to apply the “compelling government interest”
test to a claim brought solely under the Free Exercise Clause.
Id. at 881-82, 885-86. The Court acknowledged, however,
that although the Constitution does not require a compelling
interest test in such a case, legislation could impose one. Id.
at 890.

   In RFRA, enacted three years later, Congress made formal
findings that the Court’s decision in Smith “virtually elimi-
nated the requirement that the government justify burdens on
religious exercise imposed by laws neutral toward religion,”
and that “the compelling interest test as set forth in prior Fed-
eral court rulings is a workable test for striking sensible bal-
ances between religious liberty and competing prior
governmental interests.” Pub. L. No. 103-141, § 2(a), 107
Stat. 1488, 1488 (1993) (codified at 42 U.S.C. § 2000bb(a)).
Congress declared that the purposes of RFRA were “to pro-
vide a claim or defense to persons whose religious exercise is
substantially burdened by government” and “to restore the
compelling interest test as set forth in Sherbert v. Verner, 374
U.S. 398 (1963) and Wisconsin v. Yoder, 406 U.S. 205 (1972)
and to guarantee its application in all cases where free exer-
cise of religion is substantially burdened.” Id. § 2(b), 107 Stat.
at 1488 (codified at 42 U.S.C. § 2000bb(b)). In this initial ver-
sion of RFRA, adopted in 1993, Congress defined “exercise
of religion” as “exercise of religion under the First Amend-
ment to the Constitution.” Id. § 5, 107 Stat. at 1489 (codified
at 42 U.S.C. § 2000bb-2(4) (1994) (repealed)).

   In 1997, in City of Boerne v. Flores, 521 U.S. 507 (1997),
the Supreme Court held RFRA unconstitutional as applied to
state and local governments because it exceeded Congress’s
authority under § 5 of the Fourteenth Amendment. Id. at 529,
534-35. The Court did not, however, invalidate RFRA as
applied to the federal government. See Guam v. Guerrero,
290 F.3d 1210, 1220-21 (9th Cir. 2002) (holding RFRA con-
stitutional as applied to the federal government). Three years
                   NAVAJO NATION v. USFS                  2843
later, in response to City of Boerne, Congress enacted the
Religious Land Use and Institutionalized Persons Act of 2000
(“RLUIPA”). Pub. L. No. 106-274, 114 Stat. 803 (codified at
42 U.S.C. §§ 2000cc et seq.). RLUIPA prohibits state and
local governments from imposing substantial burdens on the
exercise of religion through prisoner or land-use regulations.
42 U.S.C. §§ 2000cc, 2000cc-1. In addition, RLUIPA
replaced RFRA’s original, constitution-based definition of
“exercise of religion” with the broader definition quoted
above. RLUIPA §§ 7-8, 114 Stat. at 806-07. Under RLUIPA,
and under RFRA after its amendment by RLUIPA in 2000,
“exercise of religion” is defined to include “any exercise of
religion, whether or not compelled by, or central to, a system
of religious belief.” 42 U.S.C. § 2000bb-2(4), 2000cc-
5(7)(A).

   In several ways, RFRA provides greater protection for reli-
gious practices than did the Supreme Court’s pre-Smith free
exercise cases. First, as we have previously noted, RFRA
“goes beyond the constitutional language that forbids the
‘prohibiting’ of the free exercise of religion and uses the
broader verb ‘burden’: a government may burden religion
only on the terms set out by the new statute.” United States
v. Bauer, 84 F.3d 1549, 1558 (9th Cir. 1996) (as amended).
Cf. U.S. Const. amd. 1 (“Congress shall make no law . . . pro-
hibiting the free exercise [of religion].”); Lyng v. Nw. Indian
Cemetery Protective Ass’n, 485 U.S. 439, 451 (1988) (“The
crucial word in the constitutional text is ‘prohibit’: ‘For the
Free Exercise Clause is written in terms of what the govern-
ment cannot do to the individual, not in terms of what the
individual can exact from the government.’ ” (quoting Sher-
bert, 374 U.S. at 412 (Douglas, J., concurring))).

  Second, as the Supreme Court noted in City of Boerne,
RFRA provides stronger protection for free exercise than the
First Amendment did under the pre-Smith cases because “the
Act imposes in every case a least restrictive means require-
2844                NAVAJO NATION v. USFS
ment — a requirement that was not used in the pre-Smith
jurisprudence RFRA purported to codify.” 521 U.S. at 535.

   Third, RFRA provides broader protection for free exercise
because it applies Sherbert’s compelling interest test “in all
cases” where the free exercise of religion is substantially bur-
dened. 42 U.S.C. § 2000bb(b). Prior to Smith, the Court had
refused to apply the compelling interest analysis in various
contexts, exempting entire classes of free exercise cases from
such heightened scrutiny. Smith, 494 U.S. at 883 (“In recent
years, we have abstained from applying the Sherbert test (out-
side the unemployment compensation field) at all.”); see, e.g.,
O’Lone v. Estate of Shabazz, 482 U.S. 342, 349 (1987) (not
applicable to prison regulations); Bowen v. Roy, 476 U.S. 693,
707 (1986) (Burger, J., for plurality) (not applicable in enforc-
ing “facially neutral and uniformly applicable requirement for
the administration of welfare programs”); Goldman v. Wein-
berger, 475 U.S. 503, 506-07 (1986) (not applicable to mili-
tary regulations).

   Finally, and perhaps most important, Congress expanded
the statutory protection for religious exercise in 2000 by
amending RFRA’s definition of “exercise of religion.” Under
the amended definition — “any exercise of religion, whether
or not compelled by, or central to, a system of religious
belief” — RFRA now protects a broader range of religious
conduct than the Supreme Court’s interpretation of “exercise
of religion” under the First Amendment. See Guru Nanak Sikh
Soc’y v. County of Sutter, 456 F.3d 978, 995 n.21 (9th Cir.
2006) (noting same). To the extent that our RFRA cases prior
to RLUIPA depended on a narrower definition of “religious
exercise,” those cases are no longer good law. See, e.g., Bry-
ant v. Gomez, 46 F.3d 948, 949 (9th Cir. 1995) (burden must
prevent adherent “from engaging in conduct or having a reli-
gious experience which the faith mandates” and must be “an
interference with a tenet or belief that is central to religious
doctrine” (quoting Graham v. Comm’r, 822 F.2d 844, 850-51
(9th Cir. 1987)); Stefanow v. McFadden, 103 F.3d 1466, 1471
                       NAVAJO NATION v. USFS                 2845
(9th Cir. 1996) (no substantial burden because prisoner was
not prevented from “engaging in any practices mandated by
his religion”); Goehring v. Brophy, 94 F.3d 1294, 1299 (9th
Cir. 1996) (plaintiffs failed to establish “a substantial burden
on a central tenet of their religion”). The district court in this
case therefore erred by disregarding the amended definition
and requiring Appellants to prove that the proposed action
would prevent them “from engaging in conduct or having a
religious experience which the faith mandates.” 408 F. Supp.
2d at 904 (quoting Worldwide Church of God, Inc. v. Phila-
delphia Church of God, Inc., 227 F.3d 1110, 1121 (9th Cir.
2000), decided before RLUIPA’s passage) (emphasis added).

   Even after RLUIPA, RFRA plaintiffs must prove that the
burden on their religious exercise is “substantial.” The burden
must be “more than an ‘inconvenience,’ ” Guerrero, 290 F.3d
at 1222 (quoting Worldwide Church of God, 227 F.3d at
1121), and must prevent the plaintiff “from engaging in [reli-
gious] conduct or having a religious experience,” Bryant, 46
F.3d at 949 (quoting Graham, 822 F.2d at 850-51). Thus, in
addressing the tribes’ RFRA claim we must answer the fol-
lowing questions: (1) What is the “exercise of religion” in
which the tribal members engage with respect to the San
Francisco Peaks? (2) What “burden,” if any, would be
imposed on that exercise of religion if the proposed expansion
of the Snowbowl went forward? (3) If there is a burden,
would the burden be “substantial”? (4) If there would be a
substantial burden, can the “application of the burden” to the
tribal members be justified as “in furtherance of a compelling
governmental interest” and “the least restrictive means of fur-
thering that compelling governmental interest”? We address
these questions in turn.

                  A.     “Exercise of Religion”

  [2] RFRA protects “any exercise of religion, whether or not
compelled by, or central to, a system of religious belief.” 42
U.S.C. §§ 2000bb-2(4), 2000cc-5(7)(A). The district court
2846                NAVAJO NATION v. USFS
stated that it was not “challenging the honest religious beliefs
of any witness.” Nor do Appellees dispute the sincerity of
Appellants’ testimony concerning their religious beliefs and
practices. Indeed, Appellees concede that the Peaks as a
whole are significant to Appellants’ “exercise of religion.”
We focus our analysis on the Peaks’ significance to the Hopi
and Navajo, and to a lesser extent on the Hualapai and Hava-
supai.

                         1.   The Hopi

   Hopi religious practices center on the Peaks. As stated by
the district court, “The Peaks are where the Hopi direct their
prayers and thoughts, a point in the physical world that
defines the Hopi universe and serves as the home of the
Kachinas, who bring water, snow and life to the Hopi peo-
ple.” 408 F. Supp. 2d at 894. The Hopi have been making pil-
grimages to the Peaks since at least 1540, when they first
encountered Europeans, and probably long before that.

   The Hopi believe that when they emerged into this world,
the clans journeyed to the Peaks (or Nuvatukyaovi, “high
place of snow”) to receive instructions from a spiritual pres-
ence, Ma’saw. At the Peaks, they entered a spiritual covenant
with Ma’saw to take care of the land, before they migrated
down to the Hopi villages. The Hopi re-enact their emergence
from the Peaks annually, and Hopi practitioners look to the
Peaks in their daily songs and prayers as a place of tranquility,
sanctity, and purity.

   The Peaks are also the primary home of the powerful spiri-
tual beings called Katsinam (Hopi plural of Katsina, or
Kachina in English). Hundreds of specific Katsinam personify
the spirits of plants, animals, people, tribes, and forces of
nature. The Katsinam are the spirits of Hopi ancestors, and the
Hopi believe that when they die, their spirits will join the Kat-
sinam on the Peaks. As spiritual teachers of “the Hopi way,”
the Katsinam teach children and remind adults of the moral
                    NAVAJO NATION v. USFS                  2847
principles by which they must live. These principles are
embodied in traditional songs given by the Katsinam to the
Hopi and sung by the Hopi in their everyday lives. One Hopi
practitioner compared these songs to sermons, which children
understand simplistically but which adults come to understand
more profoundly. Many of these songs focus on the Peaks.

   Katsinam serve as intermediaries between the Hopi and the
higher powers, carrying prayers from the Hopi villages to the
Peaks on an annual cycle. From July through January, the
Katsinam live on the Peaks. In sixteen days of ceremonies and
prayers at the winter solstice, the Hopi pray and prepare for
the Katsinam’s visits to the villages. In February or March,
the Katsinam begin to arrive, and the Hopi celebrate with
nightly dances at which the Katsinam appear in costume and
perform. The Katsinam stay while the Hopi plant their corn
and it germinates. Then, in July, the Hopi mark the Katsi-
nam’s departure for the Peaks.

   The Hopi believe that pleasing the Katsinam on the Peaks
is crucial to their livelihood. Appearing in the form of clouds,
the Katsinam are responsible for bringing rain to the Hopi vil-
lages from the Peaks. The Katsinam must be treated with
respect, lest they refuse to bring the rains from the Peaks to
nourish the corn crop. In preparation for the Katsinam’s
arrival, prayer sticks and feathers are delivered to every mem-
ber of the village, which they then deposit in traditional loca-
tions, praying for the spiritual purity to receive the Katsinam.
The Katsinam will not arrive until the peoples’ hearts are in
the right place, a state they attempt to reach through prayers
directed at the spirits on the Peaks.

   The Hopi have at least fourteen shrines on the Peaks. Every
year, religious leaders select members of each of the approxi-
mately 40 congregations, or kiva, among the twelve Hopi vil-
lages to make a pilgrimage to the Peaks. They gather from the
Peaks both water for their ceremonies and boughs of Douglas
fir worn by the Katsinam in their visits to the villages.
2848               NAVAJO NATION v. USFS
                      2.   The Navajo

   The Peaks are also of fundamental importance to the reli-
gious beliefs and practices of the Navajo. The district court
found, “[T]he Peaks are considered . . . to be the ‘Mother of
the Navajo People,’ their essence and their home. The whole
of the Peaks is the holiest of shrines in the Navajo way of
life.” 408 F. Supp. 2d at 889. Considering the mountain “like
family,” the Navajo greet the Peaks daily with prayer songs,
of which there are more than one hundred relating to the four
mountains sacred to the Navajo. Witnesses described the
Peaks as “our leader” and “very much an integral part of our
life, our daily lives.”

   The Navajo creation story revolves around the Peaks. The
mother of humanity, called the Changing Woman and com-
pared by one witness to the Virgin Mary, resided on the Peaks
and went through puberty there, an event which the people
celebrated as a gift of new life. Following this celebration,
called the kinaalda, the Changing Woman gave birth to twins,
from whom the Navajo are descended. The Navajo believe
that the Changing Woman’s kinaalda gave them life genera-
tion after generation. Young women today still celebrate their
own kinaalda with a ceremony one witness compared to a
Christian confirmation or a Jewish bat mitzvah. The cere-
mony sometimes involves water especially collected from the
Peaks because of the Peaks’ religious significance.

   The Peaks are represented in the Navajo medicine bundles
found in nearly every Navajo household. The medicine bun-
dles are composed of stones, shells, herbs, and soil from each
of four sacred mountains. One Navajo practitioner called the
medicine bundles “our Bible,” because they have “embedded”
within them “the unwritten way of life for us, our songs, our
ceremonies.” The practitioner traced their origin to the
Changing Woman: When her twins wanted to find their
father, Changing Woman instructed them to offer prayers to
the Peaks and conduct ceremonies with medicine bundles.
                    NAVAJO NATION v. USFS                  2849
The Navajo believe that the medicine bundles are conduits for
prayers; by praying to the Peaks with a medicine bundle con-
taining soil from the Peaks, the prayer will be communicated
to the mountain.

   As their name suggests, medicine bundles are also used in
Navajo healing ceremonies, as is medicine made with plants
collected from the Peaks. Appellant Norris Nez, a Navajo
medicine man, testified that “like the western doctor has his
black bag with needles and other medicine, this bundle has in
there the things to apply medicine to a patient.” Explaining
why he loves the mountain as his mother, he testified, “She
is holding medicine and things to make us well and healthy.
We suckle from her and get well when we consider her our
Mother.” Nez testified that he collects many different plants
from the Peaks to make medicine.

  The Peaks play a role in every Navajo religious ceremony.
The medicine bundle is placed to the west, facing the Peaks.
In the Blessingway ceremony, called by one witness “the
backbone of our ceremony” because it is performed at all cer-
emonies’ conclusion, the Navajo pray to the Peaks by name.

   The purity of nature, including the Peaks, plays an impor-
tant part in Navajo beliefs. Among other things, it affects how
a medicine bundle — described by one witness as “a living
basket” — is made. The making of a medicine bundle is pre-
ceded by a four-day purification process for the medicine man
and the keeper of the bundle. By Navajo tradition, the medi-
cine bundle should be made with leather from a buck that is
ritually suffocated; the skin cannot be pierced by a weapon.
Medicine bundles are “rejuvenated” regularly, every few
years, by replacing the ingredients with others gathered on
pilgrimages to the Peaks and three other sacred mountains.

   The Navajo believe their role on earth is to take care of the
land. They refer to themselves as nochoka dine, which one
witness translated as “people of the earth” or “people put on
2850                NAVAJO NATION v. USFS
the surface of the earth to take care of the lands.” They
believe that the Creator put them between four sacred moun-
tains of which the westernmost is the Peaks, or Do’ok’oos-liid
(“shining on top,” referring to its snow), and that the Creator
instructed them never to leave this homeland. Although the
whole reservation is sacred to the Navajo, the mountains are
the most sacred part. One witness drew an analogy to a
church, with the area within the mountains as the part of the
church where the people sit, and the Peaks as “our altar to the
west.”

   As in Hopi religious practice, the Peaks are so sacred in
Navajo beliefs that, as testified by Joe Shirley, Jr., President
of the Navajo Nation, a person “cannot just voluntarily go up
on this mountain at any time. It’s — it’s the holiest of shrines
in our way of life. You have to sacrifice. You have to sing
certain songs before you even dwell for a little bit to gather
herbs, to do offerings.” After the requisite preparation, the
Navajo go on pilgrimages to the Peaks to collect plants for
ceremonial and medicinal use.

                      3.   The Hualapai

    The Peaks figure centrally in the beliefs of the Hualapai.
The Hualapai creation story takes place on the Peaks. The
Hualapai believe that at one time the world was deluged by
water, and the Hualapai put a young girl on a log so that she
could survive. She landed on the Peaks, alone, and washed in
the water. In the water, she conceived a son, who was a man
born of water. She washed again, and conceived another son.
These were the twin warriors or war gods, from whom the
Hualapai are today descended. Later, one of the twins became
ill, and the other collected plants and water from the Peaks,
thereby healing his brother. From this story comes the Huala-
pai belief that the mountain and its water and plants are sacred
and have medicinal properties. One witness called the story of
the deluge, the twins, and their mother “our Bible story” and
drew a comparison to Noah’s ark. As in Biblical parables and
                     NAVAJO NATION v. USFS                    2851
stories, Hualapai songs and stories about the twins are infused
with moral principles.

   Hualapai spiritual leaders travel to the Peaks to deliver
prayers. Like the Hopi and the Navajo, the Hualapai believe
that the Peaks are so sacred that one has to prepare oneself
spiritually to visit. A spiritual leader testified that he prays to
the Peaks every day and fasts before visiting to perform the
prayer feather ceremony. In the prayer feather ceremony, a
troubled family prays into an eagle feather for days, and the
spiritual leader delivers it to the Peaks; the spirit of the eagle
then carries the prayer up the mountain and to the creator.

   The Hualapai collect water from the Peaks. Hualapai reli-
gious ceremonies revolve around water, and they believe
water from the Peaks is sacred. In their sweat lodge purifica-
tion ceremony, the Hualapai add sacred water from the Peaks
to other water, and pour it onto heated rocks to make steam.
In a healing ceremony, people seeking treatment drink from
the water used to produce the steam and are cleansed by
brushing the water on their bodies with feathers. At the con-
clusion of the healing ceremony, the other people present also
drink the water. A Hualapai tribal member who conducts
healing ceremonies testified that water from the Peaks is used
to treat illnesses of “high parts” of the body like the eyes,
sinuses, mouth, throat, and brain, including tumors, meningi-
tis, forgetfulness, and sleepwalking. He testified that the
Peaks are the only place to collect water with those medicinal
properties, and that he travels monthly to the Peaks to collect
it from Indian Springs, which is lower on the mountain and
to the west of the Snowbowl. The water there has particular
significance to the Hualapai because the tribe’s archaeological
sites are nearby.

   In another Hualapai religious ceremony, when a baby has
a difficult birth, a Hualapai spiritual leader brings a portion of
the placenta to the Peaks so that the child will be strong like
the twins and their mother in the Hualapai creation story. The
2852                NAVAJO NATION v. USFS
Hualapai also grind up ponderosa pine needles from the Peaks
in sacred water from the Peaks to aid women in childbirth.

   A Hualapai religious law forbids mixing the living and the
dead. In testimony in the district court, a spiritual leader gave
the example of washing a baby or planting corn immediately
after taking part in a death ceremony. Mixing the two will
cause a condition that was translated into English as “the
ghost sickness.” The leader testified that purification after
“touching death” depends on the intensity of the encounter. If
he had just touched the dead person’s clothes or belongings,
he might be purified in four days, but if he touched a body,
it would require a month.

                      4.   The Havasupai

   The Peaks are similarly central to the beliefs of the Havasu-
pai, as the Forest Service has acknowledged in the FEIS: “The
Hualapai and the Havasupai perceive the world as flat,
marked in the center by the San Francisco Peaks, which were
visible from all parts of the Havasupai territory except inside
the Grand Canyon. The commanding presence of the Peaks
probably accounts for the Peaks being central to the Havasu-
pai beliefs and traditions, even though the Peaks themselves
are on the edge of their territory.” The Chairman of the Hava-
supai testified that the Peaks are the most sacred religious site
of the Havasupai: “That is where life began.” The Havasupai
believe that when the earth was submerged in water, the
tribe’s “grandmother” floated on a log and landed and lived
on the Peaks, where she survived on water from the Peaks’
springs and founded the tribe.

   Water is central to the religious practices of the Havasupai.
Although they do not travel to the Peaks to collect water,
Havasupai tribal members testified that they believe the water
in the Havasu creek that they use in their sweat lodges comes
ultimately from the Peaks, to which they pray daily. They
believe that spring water is a living, life-giving, pure sub-
                    NAVAJO NATION v. USFS                     2853
stance, and they do not use tap water in their religious prac-
tices. They perform sweat lodge ceremonies, praying and
singing as they use the spring water to make steam; they
believe that the steam is the breath of their ancestors, and that
by taking it into themselves they are purified, cleansed, and
healed. They give water to the dead to take with them on their
journey, and they use it to make medicines. The Havasupai
also gather rocks from the Peaks to use for making steam.

                         B.   “Burden”

  The proposed expansion of the Snowbowl entails deposit-
ing millions of gallons of treated sewage effluent — often
euphemistically called “reclaimed water” — from the City of
Flagstaff onto the Peaks. Depending on weather conditions,
substantially more than 100 million gallons of effluent could
be deposited over the course of the winter ski season.

  Before treatment, the raw sewage consists of waste dis-
charged into Flagstaff’s sewers by households, businesses,
and industry. The FEIS describes the treatment performed by
Flagstaff:

    In the primary treatment stage, solids settle out as
    sludge . . . . Scum and odors are also removed . . . .
    Wastewater is then gravity-fed for secondary treat-
    ment through the aeration/denitrification process,
    where biological digestion of waste occurs . . . . in
    which a two-stage anoxic/aerobic process removes
    nitrogen, suspended solids, and [digestible organic
    matter] from the wastewater. The secondary clarifi-
    ers remove the by-products generated by this biolog-
    ical process, recycle microorganisms back into the
    process from return activated sludge, and separate
    the solids from the waste system. The waste sludge
    is sent to [a different plant] for treatment. The water
    for reuse then passes through the final sand and
    anthracite filters prior to disinfection by ultraviolet
2854                NAVAJO NATION v. USFS
    light radiation. . . . Water supplied for reuse is fur-
    ther treated with a hypochlorite solution to assure
    that residual disinfection is maintained . . . .

   Although the treated sewage effluent would satisfy the
requirements of Arizona law for “reclaimed water,” the FEIS
explains that the treatment does not produce pure water:
“Fecal coliform bacteria, which are used as an indicator of
microbial pathogens, are typically found at concentrations
ranging from 105 to 107 colony-forming units per 100 millili-
ters (CFU/100 ml) in untreated wastewater. Advanced waste-
water treatment may remove as much as 99.9999+ percent of
the fecal coliform bacteria; however, the resulting effluent has
detectable levels of enteric bacteria, viruses, and protazoa,
including Cryptosporidium and Giardia.” According to Ari-
zona law, the treated sewage effluent must be free of “detect-
able fecal coliform organisms” in only “four of the last seven
daily reclaimed water samples.” Ariz. Admin. Code § R18-
11-303(B)(2)(a). The FEIS acknowledges that the treated
sewage effluent also contains “many unidentified and unregu-
lated residual organic contaminants.”

   Treated sewage effluent may be safely and beneficially
used for many purposes. See id. § R18-11-309 Tbl. A (2005)
(permitting its use for, inter alia, irrigating food crops and
schoolyards; flushing toilets; fire protection; certain commer-
cial air conditioning systems; and non-self-service car
washes); 7 Ariz. Admin. Reg. 876 (Feb. 16, 2001) (“Water
reclamation is an important strategy for conserving and aug-
menting Arizona’s drinking water supply. Source substitution,
or the reuse of reclaimed water to replace potable water that
currently is used for nonpotable purposes, conserves higher
quality sources of water for human consumption and domestic
purposes.”). However, the Arizona Department of Environ-
mental Quality (“ADEQ”) requires that users take precautions
to avoid human ingestion. For example, users must “place and
maintain signage . . . so the public is informed that reclaimed
water is in use and that no one should drink from the system.”
                     NAVAJO NATION v. USFS                    2855
Ariz. Admin. Code § R18-9-704(H) (2005). Irrigation users
must employ “application methods that reasonably preclude
human contact with reclaimed water,” including preventing
“contact with drinking fountains, water coolers, or eating
areas,” and preventing the treated effluent from “standing on
open access areas during normal periods of use.” Id. § R18-9-
704(F). Arizona law prohibits uses involving “full-immersion
water activity with a potential of ingestion,” and “evaporative
cooling or misting.” Id. § R18-9-704(G)(2).

   Under the proposed action challenged in this case, up to 1.5
million gallons per day of treated sewage effluent would be
sprayed on the mountain from November through February.
In November and December, the Snowbowl would use it to
build a base layer of artificial snow over 205.3 acres of Hum-
phrey’s Peak. The Snowbowl would then spray more as nec-
essary depending on the amount of natural snowfall. The
proposed action also involves constructing a reservoir on the
mountain with a surface area of 1.9 acres to hold 10 million
gallons of treated sewage effluent. The stored effluent would
allow snowmaking to continue after Flagstaff cuts off the sup-
ply at the end of February.

   The ADEQ approved the use of treated sewage effluent for
snowmaking in 2001, noting that four other states already per-
mitted its use for that purpose. 7 Ariz. Admin. Reg. 880 (Feb.
16, 2001). However, the Snowbowl would be the first ski
resort in the nation to make its snow entirely from undiluted
treated sewage effluent. The Snowbowl’s general manager
testified in the district court that no other resort in the country
currently makes its artificial snow “exclusively” out of undi-
luted sewage effluent.

   Appellants claim that the use of treated sewage effluent to
make artificial snow on the Peaks would substantially burden
their exercise of religion. Because Appellants’ religious
beliefs and practices are not uniform, the precise burdens on
religious exercise vary among the Appellants. Nevertheless,
2856                NAVAJO NATION v. USFS
the burdens fall roughly into two categories: (1) the inability
to perform a particular religious ceremony, because the cere-
mony requires collecting natural resources from the Peaks that
would be too contaminated — physically, spiritually, or both
— for sacramental use; and (2) the inability to maintain daily
and annual religious practices comprising an entire way of
life, because the practices require belief in the mountain’s
purity or a spiritual connection to the mountain that would be
undermined by the contamination.

   The first burden — the contamination of natural resources
necessary for the performance of certain religious ceremonies
— has been acknowledged and described at length by the For-
est Service. The FEIS summarizes: “Snowmaking and expan-
sion of facilities, especially the use of reclaimed water, would
contaminate the natural resources needed to perform the
required ceremonies that have been, and continue to be, the
basis for the cultural identity for many of these tribes.” Fur-
ther, “the use of reclaimed water is believed by the tribes to
be impure and would have an irretrievable impact on the use
of the soil, plants, and animals for medicinal and ceremonial
purposes throughout the entire Peaks, as the whole mountain
is regarded as a single, living entity.”

   Three Navajo practitioners’ testimony at the bench trial
echoed the Forest Service’s assessment in describing how the
proposed action would prevent them from performing various
ceremonies. Larry Foster, a Navajo practitioner who is train-
ing to become a medicine man, testified that “once water is
tainted and if water comes from mortuaries or hospitals, for
Navajo there’s no words to say that that water can be
reclaimed.” He further testified that he objected to the current
use of the Peaks as a ski area, but that using treated sewage
effluent to make artificial snow on the Peaks would be “far
more serious.” He explained, “I can live with a scar as a
human being. But if something is injected into my body that
is foreign, a foreign object — and reclaimed water, in my
opinion, could be water that’s reclaimed through sewage,
                    NAVAJO NATION v. USFS                   2857
wastewater, comes from mortuaries, hospitals, there could be
disease in the waters — and that would be like injecting me
and my mother, my grandmother, the Peaks, with impurities,
foreign matter that’s not natural.”

   Foster testified that if treated sewage effluent were used on
the Peaks he would no longer be able to go on the pilgrimages
to the Peaks that are necessary to rejuvenate the medicine
bundles, which are, in turn, a part of every Navajo healing
ceremony. He explained:

    Your Honor, our way of life, our culture we live in
    — we live in the blessingway, in harmony. We try
    to walk in harmony, be in harmony with all of
    nature. And we go to all of the sacred mountains for
    protection. We go on a pilgrimage similar to Mus-
    lims going to Mecca. And we do this with so much
    love, commitment and respect. And if one mountain
    — and more in particularly with the San Francisco
    Peaks — which is our bundle mountain, or sacred,
    bundle mountain, were to be poisoned or given for-
    eign materials that were not pure, it would create an
    imbalance — there would not be a place among the
    sacred mountains. We would not be able to go there
    to obtain herbs or medicines to do our ceremonies,
    because that mountain would then become impure. It
    would not be pure anymore. And it would be a dev-
    astation for our people.

   Appellant Navajo medicine man Norris Nez testified that
the proposed action would prevent him from practicing as a
medicine man. He told the district court that the presence of
treated sewage effluent would “ruin” his medicine, which he
makes from plants collected from the Peaks. He also testified
that he would be unable to perform the fundamental Blessing-
way ceremony, because “all [medicine] bundles will be
affected and we will have nothing to use eventually.”
2858                NAVAJO NATION v. USFS
   Foster, Nez, and Navajo practitioner Steven Begay testified
that because they believe the mountain is an indivisible living
entity, the entire mountain would be contaminated even if the
millions of gallons of treated sewage effluent are put onto
only one area of the Peaks. According to Foster, Nez, and
Begay, there would be contamination even on those parts of
the Peaks where the effluent would not come into physical
contact with particular plants or ceremonial areas. To them,
the contamination is not literal in the sense that a scientist
would use the term. Rather, the contamination represents the
poisoning of a living being. In Foster’s words, “[I]f someone
were to get a prick or whatever from a contaminated needle,
it doesn’t matter what the percentage is, your whole body
would then become contaminated. And that’s what would
happen to the mountain.” In Nez’s words, “All of it is holy.
It is like a body. It is like our body. Every part of it is holy
and sacred.” In Begay’s words, “All things that occur on the
mountain are a part of the mountain, and so they will have
connection to it. We don’t separate the mountain.”

   The Hualapai also presented evidence that the proposed
action would prevent them from performing particular reli-
gious ceremonies. Frank Mapatis, a Hualapai practitioner and
spiritual leader who visits the Peaks approximately once a
month to collect water for ceremonies and plants for medi-
cine, testified that the use of treated sewage effluent would
prevent him from performing Hualapai sweat lodge and heal-
ing ceremonies with the sacred water from the Peaks. Mapatis
testified that he believes that the treated sewage effluent
would seep into the ground and into the spring below the
Snowbowl where he collects his sacred water, so that the
spring water would be “contaminated” by having been
“touched with death.” Because contact between the living and
the dead induces “ghost sickness,” which involves hallucina-
tions, using water touched with death in healing ceremonies
“would be like malpractice.” Further, Mapatis would become
powerless to perform the healing ceremony for ghost sickness
itself, because that ceremony requires water from the Peaks,
                    NAVAJO NATION v. USFS                       2859
the only medicine for illnesses of the upper body and head,
like hallucinations.

   The second burden the proposed action would impose —
undermining Appellants’ religious faith, practices, and way of
life by desecrating the Peaks’ purity — is also shown in the
record. The Hopi presented evidence that the presence of
treated sewage effluent on the Peaks would fundamentally
undermine all of their religious practices because their way of
life, or “beliefway,” is largely based on the idea that the Peaks
are a pure source of their rains and the home of the Katsinam.

   Leigh Kuwanwisiwma, a Hopi religious practitioner and
the director of the tribe’s Cultural Preservation Office,
explained the connection between contaminating the Peaks
and undermining the Hopi religion:

    The spiritual covenant that the Hopi clans entered
    into with the Caretaker I refer to as Ma’saw, the spir-
    itual person and the other d[ei]ties that reside — and
    the Katsina that reside in the Peaks started out with
    the mountains being in their purest form. They didn’t
    have any real intrusion by humanity.

       The purity of the spirits, as best we can acknowl-
    edge the spiritual domain, we feel were content in
    receiving the Hopi clans. So when you begin to
    intrude on that in a manner that is really disrespect-
    ful to the Peaks and to the spiritual home of the Kat-
    sina, it affects the Hopi people. It affects the Hopi
    people, because as clans left and embarked on their
    migrations and later coming to the Hopi villages, we
    experienced still a mountain and peaks that were in
    their purest form as a place of worship to go to, to
    visit, to place our offerings, the tranquility, the sanc-
    tity that we left a long time ago was still there.

Antone Honanie, a Hopi practitioner, testified that he would
have difficulty preparing for religious ceremonies, because
2860                NAVAJO NATION v. USFS
treated sewage effluent is “something you can’t get out of
your mind when you’re sitting there praying” to the mountain,
“a place where everything is supposed to be pure.” Emory
Sekaquaptewa, a Hopi tribal member and research anthropol-
ogist, testified that the desecration of the mountain would
cause Katsinam dance ceremonies to lose their religious
value. They would “simply be a performance for perfor-
mance[’s] sake” rather than “a religious effort”: “Hopi people
are raised in this belief that the mountains are a revered place.
And even though they begin with kind of a fantasy notion,
this continues to grow into a more deeper spiritual sense of
the mountain. So that any thing that interrupts this perception,
as they hold it, would tend to undermine the — the integrity
in which they hold the mountain.”

  Summarizing the Hopi’s testimony, the district court wrote:

    The individual Hopi’s practice of the Hopi way per-
    meates every part and every day of the individual’s
    life from birth to death. . . . The Hopi Plaintiffs testi-
    fied that the proposed upgrades to the Snowbowl
    have affected and will continue to negatively affect
    the way they think about the Peaks, the Kachina and
    themselves when preparing for any religious activity
    involving the Peaks and the Kachina — from daily
    morning prayers to the regular calendar of religious
    dances that occur throughout the year. . . . The Hopi
    Plaintiffs also testified that this negative effect on the
    practitioners’ frames of mind due to the continued
    and increased desecration of the home of the Kachi-
    nas will undermine the Hopi faith and the Hopi way.
    According to the Hopi, the Snowbowl upgrades will
    undermine the Hopi faith in daily ceremonies and
    undermine the Hopi faith in their Kachina ceremo-
    nies as well as their faith in the blessings of life that
    they depend on the Kachina to bring.

408 F. Supp.2d at 894-95.
                    NAVAJO NATION v. USFS                     2861
   The Havasupai presented evidence that the presence of
treated sewage effluent on the Peaks would, by contaminating
the Peaks, undermine their sweat lodge purification ceremo-
nies and could lead to the end of the ceremonies. Rex Tilousi,
Chairman of the Havasupai, testified that Havasupai religious
stories teach that the water in Havasu creek, which they use
for their sweat ceremonies, flows from the Peaks, where the
Havasupai believe life began. Although none of the three
Havasupai witnesses stated that they would be completely
unable to perform the sweat lodge ceremonies as a conse-
quence of the impurity introduced by the treated sewage efflu-
ent, Roland Manakaja, a traditional practitioner, testified that
the impurity would disrupt the ceremony:

    If I was to take the water to sprinkle the rocks to
    bring the breath of our ancestors — we believe the
    steam is the breath of our ancestors. And the rocks
    placed in the west signify where our ancestors go,
    the deceased. . . . Once the steam rises, like it does
    on the Peaks, the fog or the steam that comes off is
    creation. And once the steam comes off and it comes
    into our being, it purifies and cleanses us and we go
    to the level of trance. . . . It’s going to impact men-
    tally my spirituality. Every time I think about sprin-
    kling that water on the rocks, I’m going to always
    think about this sewer that they’re using to recharge
    the aquifer.

He further testified that he was “concerned” that the water’s
perceived impurity might cause the sweat lodge ceremony to
die out altogether, if tribal members fear “breathing the organ-
isms or the chemicals that may come off the steam.”

  C.   “Substantial Burden” on the “Exercise of Religion”

  [3] To establish a prima facie case under RFRA, a plaintiff
must show that the government’s proposed action imposes a
substantial burden on the plaintiff’s ability to practice freely
2862               NAVAJO NATION v. USFS
his or her religion. Guerrero, 290 F.3d at 1222. Although the
burden need not concern a religious practice that is “com-
pelled by, or central to, a system of religious belief,” 42
U.S.C. §§ 2000bb-2(4), 2000cc-5(7)(A), the burden “must be
more than an ‘inconvenience,’ ” Guerrero, 290 F.3d at 1222
(quoting Worldwide Church of God, 227 F.3d at 1121). The
burden must prevent the plaintiff “from engaging in [reli-
gious] conduct or having a religious experience.” Bryant, 46
F.3d at 949 (quoting Graham, 822 F.2d at 850-51).

   [4] The record supports the conclusion that the proposed
use of treated sewage effluent on the San Francisco Peaks
would impose a burden on the religious exercise of all four
tribes discussed above — the Navajo, the Hopi, the Hualapai,
and the Havasupai. However, on the record before us, that
burden falls most heavily on the Navajo and the Hopi. The
Forest Service itself wrote in the FEIS that the Peaks are the
most sacred place of both the Navajo and the Hopi; that those
tribes’ religions have revolved around the Peaks for centuries;
that their religious practices require pure natural resources
from the Peaks; and that, because their religious beliefs dic-
tate that the mountain be viewed as a whole living being, the
treated sewage effluent would in their view contaminate the
natural resources throughout the Peaks. Navajo Appellants
presented evidence in the district court that, were the pro-
posed action to go forward, contamination by the treated sew-
age effluent would prevent practitioners from making or
rejuvenating medicine bundles, from making medicine, and
from performing the Blessingway and healing ceremonies.
Hopi Appellants presented evidence that, were the proposed
action to go forward, contamination by the effluent would
fundamentally undermine their entire system of belief and the
associated practices of song, worship, and prayer, that depend
on the purity of the Peaks, which is the source of rain and
their livelihoods and the home of the Katsinam spirits.

   [5] We conclude that Appellants have shown that the use
of treated sewage effluent on the Peaks would impose a sub-
                    NAVAJO NATION v. USFS                  2863
stantial burden on their exercise of religion. This showing is
particularly strong for the Navajo and the Hopi. Because we
hold that the Navajo and the Hopi have shown a substantial
burden on their exercise of religion, we need not reach the
somewhat closer question of whether the Hualapai and the
Havasupai have also done so.

       D.   “Compelling Governmental Interest” and
                “Least Restrictive Means”

   [6] The Forest Service and the Snowbowl argue that even
if Appellants have shown a substantial burden on their reli-
gious exercise, approving the use of treated sewage effluent
to make artificial snow at a commercial ski area is “in further-
ance of a compelling governmental interest” and constitutes
“the least restrictive means of furthering that compelling gov-
ernmental interest.” 42 U.S.C. § 2000bb-1(b). “Requiring a
State to demonstrate a compelling interest and show that it has
adopted the least restrictive means of achieving that interest
is the most demanding test known to constitutional law.” City
of Boerne, 521 U.S. at 534. “[O]nly those interests of the
highest order and those not otherwise served can overbalance
legitimate claims to the free exercise of religion.” Yoder, 406
U.S. at 215.

   The Supreme Court has recently emphasized that, even
with respect to governmental interests of the highest order, a
“categorical” or general assertion of a compelling interest is
not sufficient. In Gonzales v. O Centro Espirita Beneficente,
126 S. Ct. 1211 (2006), the Court held under RFRA that the
government’s general interest in enforcing the Controlled
Substances Act was insufficient to justify the substantial bur-
den on religious exercise imposed on a small religious group
by a ban on a South American hallucinogenic plant. Id. at
1220-21. The Court stated that it did not “doubt the general
interest in promoting public health and safety . . . , but under
RFRA invocation of such general interests, standing alone, is
not enough.” Id. at 1225. “[S]trict scrutiny ‘at least requires
2864                NAVAJO NATION v. USFS
a case-by-case determination of the question, sensitive to the
facts of each particular claim.’ ” Id. at 1221 (quoting Smith,
494 U.S. at 899 (O’Connor, J., concurring in the judgment)).

   The Forest Service and the Snowbowl argued successfully
in the district court, and argue here, that approving the use of
treated sewage effluent to make artificial snow serves several
compelling governmental interests. In the words of the district
court, those compelling interests are: (1)“selecting the alterna-
tive that best achieves [the Forest Service’s] multiple-use
mandate under the National Forest Management Act,” which
includes “managing the public land for recreational uses such
as skiing”; (2) protecting public safety by “authorizing
upgrades at Snowbowl to ensure that users of the National
Forest ski area have a safe experience”; and (3) complying
with the Establishment Clause. 408 F. Supp. 2d at 906. The
district court concluded that all three were compelling govern-
mental interests and that approving the proposed action was
“the least restrictive means for achieving [the government’s]
land management decision.” Id. at 907. Before this court, the
Forest Service argues that the first two interests are compel-
ling. The Snowbowl argues that all three are compelling. We
disagree. We take the proffered interests in turn.

   [7] First, the Forest Service’s interests in managing the for-
est for multiple uses, including recreational skiing, are, in the
words of the Court in O Centro Espirita, “broadly formulated
interests justifying the general applicability of government
mandates” and are therefore insufficient on their own to meet
RFRA’s compelling interest test. 126 S. Ct. at 1220. Appel-
lants argue that approving the proposed action serves the
more particularized compelling interest in providing skiing at
the Snowbowl, because the use of artificial snow will allow
a more “reliable and consistent operating season” at one of the
only two major ski areas in Arizona, where public demand for
skiing and snowplay is strong. We are unwilling to hold that
authorizing the use of artificial snow at an already functioning
commercial ski area in order to expand and improve its facili-
                    NAVAJO NATION v. USFS                   2865
ties, as well as to extend its ski season in dry years, is a gov-
ernmental interest “of the highest order.” Yoder, 406 U.S. at
215.

   However, Appellees contend that the very survival of the
Arizona Snowbowl as a commercial ski area depends on their
being able to make artificial snow with treated sewage efflu-
ent. They point to the district court’s statement that “the evi-
dence adduced at trial demonstrates that snowmaking is
needed to maintain the viability of the Snowbowl as a public
recreational resource.” 408 F. Supp. 2d at 907. The record
does not support the conclusion that the Snowbowl will nec-
essarily cease to exist as a ski area if the proposed expansion
does not go forward. As we noted above, there were two very
dry years in 1995-96 and 2001-02. But in other recent years
there has been heavy snowfall, particularly in 1991-91, 1992-
93, 1997-98, and 2004-05. Relying only on natural snowfall,
the Snowbowl has been in operation since 1938, and it under-
took a substantial expansion in 1979. The current owners pur-
chased the Snowbowl in 1992 for $4 million and now seek
approval for another substantial expansion. It is clear that the
current owners expect that the resort would be substantially
more profitable — and the income stream more consistent —
if the expansion were allowed to proceed. But the evidence in
the record does not support a conclusion that the Snowbowl
will necessarily go out of business if it is required to continue
to rely on natural snow and to remain a relatively small, low-
key resort. The current owners may or may not decide to con-
tinue their ownership. But a sale by the current owners is not
the same thing as the closure of the Snowbowl.

   Even if there is a substantial threat that the Snowbowl will
close entirely as a commercial ski area, we are not convinced
that there is a compelling governmental interest in allowing
the Snowbowl to make artificial snow from treated sewage
effluent to avoid that result. We are struck by the obvious fact
that the Peaks are located in a desert. It is (and always has
been) predictable that some winters will be dry. The then-
2866                NAVAJO NATION v. USFS
owners of the Snowbowl knew this when they expanded the
Snowbowl in 1979, and the current owners knew this when
they purchased it in 1992. The current owners now propose
to change these natural conditions by adding treated sewage
effluent. Under some circumstances, such a proposal might be
permissible or even desirable. But in this case, we cannot con-
clude that authorizing the proposed use of treated sewage
effluent is justified by a compelling governmental interest in
providing public recreation. Even without the proposed
expansion of the Snowbowl, members of the public will con-
tinue to enjoy many recreational activities on the Peaks. Such
activities include the downhill skiing that is now available at
the Snowbowl. Even if the Snowbowl were to close (which
we think is highly unlikely), continuing recreational activities
on the Peaks would include “motorcross, mountain biking,
horseback riding, hiking and camping,” as well as other snow-
related activities such as cross-country skiing, snowshoeing,
and snowplay. 408 F. Supp. 2d at 884.

   [8] Second, although the Forest Service undoubtedly has a
general interest in ensuring public safety on federal lands,
there has been no showing that approving the proposed action
advances that interest. Appellees provide no specific evidence
that skiing at the Snowbowl in its current state is unsafe. We
do recognize that there is a legitimate safety concern about
snowplay by non-skiers who drive to the Peaks and park
beside the road. The district court found that such snowplay
next to the road has caused “injuries, traffic management
issues, garbage, and sanitation problems.” Id. at 899. The
court further found that the proposed action would address the
problem by creating an off-road managed snowplay area as
part of the Snowbowl complex. Id. But this safety concern is
not a compelling interest that can justify the burden imposed
by the Snowbowl’s expansion. The current dangerous condi-
tions caused by snowplay do not result from the operation of
the Snowbowl. These conditions are not caused by skiers, but
rather by non-skiers who have stopped along the road. The
Snowbowl’s proposed expansion and the creation of a snow-
                    NAVAJO NATION v. USFS                   2867
play area at the Snowbowl have become linked only because
the Forest Service insisted in the negotiations leading to the
FEIS that, in return for approval of the proposed action, the
Snowbowl agrees to create a snowplay area for non-skiers.
Even assuming that the safety concerns motivating the cre-
ation of the snowplay area are a compelling interest, we do
not agree that inducing a commercial ski resort, which is not
the source of the danger, to develop a snowplay area as a quid
pro quo for approval of the resort’s use of treated sewage
effluent is the least restrictive means of furthering that inter-
est.

    [9] Third, approving the proposed action does not serve a
compelling governmental interest in avoiding conflict with
the Establishment Clause. The Supreme Court has repeatedly
held that the Constitution “affirmatively mandates accommo-
dation, not merely tolerance, of all religions, and forbids hos-
tility toward any.” Lynch v. Donnelly, 465 U.S. 668, 673
(1984). “Anything less would require the ‘callous indiffer-
ence’ we have said was never intended by the Establishment
Clause.” Id. (citations omitted); see also Hobbie v. Unemp.
App. Comm’n of Fla., 480 U.S. 136, 144-45 (1987) (“This
Court has long recognized that the government may (and
sometimes must) accommodate religious practices and that it
may do so without violating the Establishment Clause.”).
Declining to allow a commercial ski resort in a national forest
to put treated sewage effluent on a sacred mountain is an
accommodation that, in our view, falls far short of an Estab-
lishment Clause violation. Indeed, the Forest Service does not
argue that avoiding a conflict with the Establishment Clause
is a compelling interest served by the proposed action. Only
the Snowbowl makes that argument.

  In support of its argument, the Snowbowl cites Estate of
Thornton v. Caldor, Inc., 472 U.S. 703 (1985), in which the
Supreme Court struck down a statute allowing all Sabbath
observers “an absolute and unqualified right not to work on
whatever day they designate as their Sabbath,” because the
2868                 NAVAJO NATION v. USFS
law’s primary effect was to advance religion by “impos[ing]
on employers and employees an absolute duty to conform
their business practices to the particular religious practices of
the employee by enforcing observance of the Sabbath the
employee unilaterally designates.” Id. at 709. The Snowbowl
argues that holding for Appellants would absolutely privilege
Appellants’ religious beliefs and practices over all other inter-
ests. This is not the case.

   The district court found, and the evidence in the record sup-
ports, that Appellants believe that “the presence of the Snow-
bowl desecrates the mountain,” regardless of the use of
treated sewage effluent. Indeed, representatives of several of
the tribes brought an unsuccessful First Amendment Free
Exercise challenge to the 1979 expansion of the Snowbowl on
that basis. Wilson v. Block, 708 F.2d 735, 739-45 (D.C. Cir.
1983). In Appellants’ view, the proposed action, including the
use of treated sewage effluent, would only “further desecrate
their sacred mountain.” 408 F. Supp. 2d at 888 (emphasis
added). Absolutely valuing Appellants’ religious beliefs over
all other interests would require shutting down the existing
operation of the Snowbowl — an option that was not consid-
ered as one of the three main alternatives in the FEIS and is
not now sought by Appellants. In our view, declining to
authorize the use of treated sewage effluent on the Peaks does
not absolutely vindicate Appellants’ interests. Rather, such a
refusal is a permitted accommodation to avoid “callous indif-
ference.” Lynch, 465 U.S. at 673.

   [10] We therefore hold that Appellees have not demon-
strated that approving the proposed action serves a compelling
governmental interest by the least restrictive means.

       E.   Lyng v. Northwest Indian Cemetery Protection
                          Association

   Appellees rely heavily on perceived similarities between
this case and Lyng v. Northwest Indian Cemetery Assoc’n,
                    NAVAJO NATION v. USFS                  2869
485 U.S. 439 (1988), to argue that the proposed action does
not violate RFRA. In Lyng, the Forest Service sought to build
a six-mile section of road connecting two pre-existing roads
in the Chimney Rock area of the Six Rivers National Forest
in northern California. Id. at 442. This area had historically
been used by several Indian tribes for religious purposes. The
route selected for the road was “removed as far as possible
from the sites used by contemporary Indians for specific spiri-
tual activities.” Id. at 443. “Alternative routes . . . were
rejected because they would have required the acquisition of
private land, had serious soil stability problems, and would in
any event have traversed areas having ritualistic value to
American Indians.” Id.

   [11] Plaintiffs, including an Indian organization and several
individual tribal members, challenged the proposed road
under the Free Exercise Clause of the First Amendment, con-
tending that their religious practices required use of undis-
turbed “prayer seats” in the Chimney Rock area. Id. at 443,
453. In their words, “ ‘Prayer seats are oriented so there is an
unobstructed view, and the practitioner must be surrounded
by undisturbed naturalness.’ ” Id. at 453 (emphasis added by
the Court). The Court was willing to “assume that the threat
to the efficacy of at least some religious practices [posed by
the proposed road] is extremely grave.” Id. at 451. The Court
nonetheless held that building the proposed road did not vio-
late the Free Exercise Clause. In the Court’s view, there was
no principled basis for distinguishing the plaintiffs’ suit from
a suit in which tribal members “might seek to exclude all
human activity but their own from sacred areas of the public
lands.” Id. at 452-53.

   [12] For two reasons, Lyng does not control the result in
this case. First, the plaintiffs’ challenge in Lyng was brought
directly under the Free Exercise Clause. As we discuss, supra,
the standard that must be satisfied to justify a burden on the
exercise of religion under RFRA is significantly more
demanding than the standard under the Free Exercise Clause.
2870                NAVAJO NATION v. USFS
Most importantly, “exercise of religion” is defined more
broadly under RFRA than “free exercise” under the First
Amendment. Further, the test for a prima facie case under
RFRA is whether there is a “substantial burden” on the exer-
cise of religion, whereas the traditional test under the First
Amendment is whether free exercise is “prohibited.” Finally,
RFRA adds a “least restrictive means” requirement to the tra-
ditional compelling governmental interest test under the Free
Exercise Clause. The net effect of these changes is that it is
easier for a plaintiff to prevail in a RFRA case than in a pure
free exercise case.

   [13] Second, the facts in Lyng were materially different
from those in this case. In Lyng, the Court was unable to dis-
tinguish the plaintiffs’ claim from one that would have
required the wholesale exclusion of non-Indians from the land
in question. Further, the government had made significant
efforts to reduce the burden, locating the planned road so as
to reduce as much as possible its auditory and visual impacts.
The Court wrote, “Except for abandoning its project entirely,
and thereby leaving the two existing segments of road to
dead-end in the middle of a National Forest, it is difficult to
see how the Government could have been more solicitous.”
Id. at 454. Finally, the failure to build the six-mile segment of
road would have left the unconnected portions of the road vir-
tually useless.

   [14] By contrast, Appellants in this case do not seek to pre-
vent use of the Peaks by others. A developed commercial ski
area already exists, and Appellants do not seek to interfere
with its current operation. There are many other recreational
uses of the Peaks, with which Appellants also do not seek to
interfere. Far from “seek[ing] to exclude all human activity
but their own from sacred areas of the public lands,” id. at
542-53, Appellants in this case are not seeking to exclude any
of the extensive human activity that now takes place on the
Peaks. The currently proposed expansion of the Snowbowl
may reasonably be seen as part of a continuing course of
                    NAVAJO NATION v. USFS                    2871
development begun in 1938 and continued in 1979. The
equivalent in this case to “abandoning the project entirely” in
Lyng would be abandoning the ski area altogether. The equiv-
alent of the Forest Service’s minimizing the adverse impact of
the road in Lyng by carefully choosing its location would be
minimizing the adverse impact of the Snowbowl by restricting
its operation to that which can be sustained by natural snow-
fall.

   The record in this case establishes the religious importance
of the Peaks to the Appellant tribes who live around it. From
time immemorial, they have relied on the Peaks, and the
purity of the Peaks’ water, as an integral part of their religious
beliefs. The Forest Service and the Snowbowl now propose to
put treated sewage effluent on the Peaks. To get some sense
of equivalence, it may be useful to imagine the effect on
Christian beliefs and practices — and the imposition that
Christians would experience — if the government were to
require that baptisms be carried out with “reclaimed water.”

   [15] The Court in Lyng denied the Free Exercise claim in
part because it could not see a stopping place. We uphold the
RFRA claim in this case in part because otherwise we cannot
see a starting place. If Appellants do not have a valid RFRA
claim in this case, we are unable to see how any Native Amer-
ican plaintiff can ever have a successful RFRA claim based
on beliefs and practices tied to land that they hold sacred.

                        F.   Conclusion

   [16] For the foregoing reasons, we conclude that Appel-
lants prevail on their RFRA claim.
NAVAJO NATION v. USFS            2873
                        Volume 2 of 2
2876                NAVAJO NATION v. USFS
          IV.    National Environmental Policy Act

   The National Environmental Protection Act requires federal
agencies to prepare a detailed environmental impact statement
for all “major Federal actions significantly affecting the qual-
ity of the human environment.” 42 U.S.C. § 4332(2)(C). This
requirement “ensures that the agency, in reaching its decision,
will have available, and will carefully consider, detailed infor-
mation concerning significant environmental impacts,” and
that “relevant information will be made available to the larger
audience that may also play a role in both the decisionmaking
process and the implementation of that decision.” Robertson
v. Methow Valley Citizens Council, 490 U.S. 332, 349 (1989).
Appellants assert five NEPA claims. We hold that only the
first of them merits reversal. We consider each in turn.

         A.     Human Ingestion of Snow Made from
                   Treated Sewage Effluent

   The Navajo Nation, the White Mountain Apache Tribe, the
Yavapai-Apache Tribe, the Havasupai Tribe, Rex Tilousi,
Dianna Uqualla, the Sierra Club, the Center for Biological
Diversity, and the Flagstaff Activist Network (“Navajo
Appellants” or “Appellants”) claim that the FEIS failed to
consider adequately the risks posed by human ingestion of
artificial snow made from treated sewage effluent.

    1.   Administrative Exhaustion and Notice of Claim
                    in the District Court

   We begin by addressing Appellees’ argument that we
should not reach the merits of this claim. Appellees argue that
Appellants failed to exhaust the claim in administrative pro-
ceedings as required by the APA, 5 U.S.C. § 704, and that
Appellants failed to raise it in the district court. We conclude
that Appellants sufficiently raised the claim in comments on
the draft EIS and in their administrative appeals, and that they
properly raised it in the district court.
                    NAVAJO NATION v. USFS                  2877
   We have interpreted the NEPA exhaustion requirements
leniently because “[r]equiring more might unduly burden
those who pursue administrative appeals unrepresented by
counsel, who may frame their claims in non-legal terms.”
Native Ecosystems Council v. Dombeck, 304 F.3d 886, 900
(9th Cir. 2002). “The plaintiffs have exhausted their adminis-
trative appeals if the appeal, taken as a whole, provided suffi-
cient notice to the [agency] to afford it the opportunity to
rectify the violations that the plaintiffs alleged.” Id. at 899;
see also Dep’t of Transp. v. Pub. Citizen, 541 U.S. 752, 764
(2004) (plaintiffs’ participation must “ ‘alert[ ] the agency to
the parties’ position and contentions,’ in order to allow the
agency to give the issue meaningful consideration” (quoting
Vt. Yankee Nuclear Power Corp. v. Natural Res. Def. Coun-
cil, Inc., 435 U.S. 519, 553 (1978)). “Claims must be raised
with sufficient clarity to allow the decision maker to under-
stand and rule on the issue raised, but there is no bright-line
standard as to when this requirement has been met and we
must consider exhaustion arguments on a case-by-case basis.”
Idaho Sporting Cong., Inc. v. Rittenhouse, 305 F.3d 957, 965
(9th Cir. 2002). The aim is to prevent plaintiffs from engaging
in “unjustified obstructionism by making cryptic and obscure
reference to matters that ‘ought to be’ considered and then,
after failing to do more to bring the matter to the agency’s
attention, seeking to have that agency determination vacated
on the ground that the agency failed to consider matters
‘forcefully presented.’ ” Vt. Yankee, 435 U.S. at 553-54.

   The core of Appellants’ claim is that the FEIS has insuffi-
ciently analyzed the risk of ingestion — particularly by chil-
dren — of artificial snow made from treated sewage effluent.
This risk was evident to the Forest Service from the begin-
ning. At least from the standpoint of public relations, the Ser-
vice responded to the risk at a very early stage. In October
2002, even before the draft EIS was published, the Service
wrote what it called a “strategic talking point.” The “talking
point” began with the question: “Will my kids get sick if they
eat artificial snow made from treated wastewater?” It contin-
2878                NAVAJO NATION v. USFS
ued with a scripted answer: “[T]his question is really one that
will be thoroughly answered in the NEPA analysis process.”
As we discuss below, the question was not subsequently
“thoroughly answered in the NEPA analysis process.”

   [17] Appellants were among those who raised this issue,
both in comments on the draft EIS and in administrative
appeals. One member of both the Sierra Club and the Flag-
staff Activist Network commented that “we’ll be dealing with
treated sewage that is undiluted with fresh water and people
who will be falling in great frozen piles of the stuff and proba-
bly accidentally swallowing some. Not to speak of children
and even adults who indulge in the winter tradition of eating
snow.” A member of the Sierra Club and the Center for Bio-
logical Diversity noted that “various disturbing trends have
led researchers to believe that environmental exposures are
contributing to children’s declining health status”: “If con-
cerns about wildlife and adult human health are not sufficient
to justify prudence in the further contamination of the north-
ern Arizona Ecosystems and waters with various societal
chemicals, then perhaps concerns for child health might dic-
tate a more conservative approach.”

  Further, the Navajo Nation, the Sierra Club, the Flagstaff
Activist Network, the Center for Biological Diversity, and the
Hualapai Tribe objected in their administrative appeal:

    The Forest Service never asked for interagency con-
    sultation on this matter from any substantial govern-
    ment authority including the National Institute of
    Child Health . . . . Children respond very differently
    from adults to drugs and pollutants. Moreover, dif-
    ferent genetic make-ups respond differently to drugs
    and chemicals. No data at all exist on the long-term
    effects of reclaimed water pollutants on two major
    populations that can be impacted by the “preferred
    alternative,” children and Native Americans.
                    NAVAJO NATION v. USFS                    2879
In their administrative appeal, the Havasupai protested that
“[k]ids and skiers will be getting a mouthful of [the water].”

   [18] These comments and appeals were more than suffi-
cient to put the Forest Service on notice of the claim and to
exhaust Appellants’ administrative remedies. The Forest Ser-
vice was obviously aware, from the outset of the NEPA pro-
cess, of possible health risks from human ingestion of
artificial snow made from treated sewage effluent, and Appel-
lants were among those who gave the Service reason to
address the issue.

   The Appellants’ complaint in the district court satisfied the
notice pleading requirement of Federal Rule of Civil Proce-
dure 8(a)(2) with respect to the risk of ingesting snow, and the
risk to children was specifically briefed in the district court at
summary judgment.

                           2.   Merits

   [19] “NEPA ‘does not mandate particular results,’ but ‘sim-
ply provides the necessary process’ to ensure that federal
agencies take a ‘hard look’ at the environmental consequences
of their actions.” Muckleshoot Indian Tribe v. U.S. Forest
Serv., 177 F.3d 800, 814 (9th Cir. 1999) (quoting Robertson,
490 U.S. at 350). Regulations require that an EIS discuss
environmental impacts “in proportion to their significance.”
40 C.F.R. § 1502.2(b). For impacts discussed only briefly,
there should be “enough discussion to show why more study
is not warranted.” Id.

   We employ a “ ‘rule of reason [standard] to determine
whether the [EIS] contains a reasonably thorough discussion
of the significant aspects of the probable environmental con-
sequences.’ ” Ctr. for Biological Diversity v. U.S. Forest
Serv., 349 F.3d 1157, 1166 (9th Cir. 2003) (first alteration in
original) (quoting Kern v. U.S. Bureau of Land Mgmt., 284
F.3d 1062, 1071 (9th Cir. 2002)). In reviewing an EIS, a court
2880               NAVAJO NATION v. USFS
must not substitute its judgment for that of the agency, but
rather must uphold the agency decision as long as the agency
has “considered the relevant factors and articulated a rational
connection between the facts found and the choice made.”
Selkirk Conservation Alliance v. Forsgren, 336 F.3d 944,
953-54 (9th Cir. 2003) (quoting Wash. Crab Producers, Inc.
v. Mosbacher, 924 F.2d 1438, 1441 (9th Cir. 1990)). This
standard consists of “a pragmatic judgment whether the EIS’s
form, content and preparation foster both informed decision-
making and informed public participation.” Churchill County
v. Norton, 276 F.3d 1060, 1071 (9th Cir. 2001) (quoting Cali-
fornia v. Block, 690 F.2d 753, 761 (9th Cir. 1982)).

   The treated sewage effluent proposed for use in making
artificial snow meets ADEQ standards for what Arizona calls
“A+ reclaimed water.” The ADEQ permits use of A+
reclaimed water for snowmaking, but it has specifically disap-
proved human ingestion of such water. Arizona law requires
users of reclaimed water to “place and maintain signage at
locations [where the water is used] so the public is informed
that reclaimed water is in use and that no one should drink
from the system.” Ariz. Admin. Code § R18-9-704(H) (2005).
Human consumption, “full-immersion water activity with a
potential of ingestion,” and “evaporative cooling or misting”
are all prohibited. Id. § R18-9-704(G)(2). Irrigation users
must employ “application methods that reasonably preclude
human contact,” including preventing “contact with drinking
fountains, water coolers, or eating areas,” and preventing the
treated effluent from “standing on open access areas during
normal periods of use.” Id. § R18-9-704(F).

   We conclude that the FEIS does not contain a reasonably
thorough discussion of the risks posed by possible human
ingestion of artificial snow made from treated sewage efflu-
ent, and does not articulate why such discussion is unneces-
sary.

   The main body of the FEIS addresses the health implica-
tions of using treated sewage effluent in subchapter 3H, “Wa-
                    NAVAJO NATION v. USFS                  2881
tershed Resources.” Much of the subchapter’s analysis
focuses on the “hydrogeologic setting” and on the effect of
the artificial snow once it has melted. The part of the subchap-
ter describing the treated sewage effluent acknowledges that
its risks to human health are not well known because it con-
tains unregulated contaminants in amounts not ordinarily
found in drinking water, including prescription drugs and
chemicals from personal care products. The subchapter con-
tains tables listing the amounts of various organic and inor-
ganic chemical constituents that have been measured in the
treated sewage effluent. One table gives a partial comparison
of Flagstaff’s monitoring data on the treated sewage effluent
to the national drinking water standards, showing that Flag-
staff has not measured thirteen of the regulated contaminants
and has not measured five of them with sufficient precision to
determine whether the treated sewage effluent meets the stan-
dards. However, the FEIS does not go on to discuss either the
health risks resulting from ingestion of the treated sewage
effluent, or the likelihood that humans — either adults or chil-
dren — will in fact ingest the artificial snow.

   Instead, the environmental impact analysis in subchapter
3H, the only part of the FEIS to discuss the characteristics of
treated sewage effluent, addresses only the impact on the
watersheds and aquifers. That analysis assesses the treated
sewage effluent’s impact after it has filtered through the
ground, a process the FEIS estimates may result in “an order
of magnitude decrease in concentration of solutes.” Thus,
although the subchapter reasonably discusses the human
health risks to downgradient users, it does not address the
risks entailed in humans’ direct exposure to, and possible
ingestion of, undiluted treated sewage effluent that has not yet
filtered through the ground.

   Appellees direct our attention to five responses to com-
ments on the draft EIS, contained in the second volume of the
FEIS. None of these brief responses constitutes a reasonable
discussion of the issue, nor does any response articulate why
2882                NAVAJO NATION v. USFS
such a discussion is unnecessary. The first response, objecting
to a commenter’s use of the word “sewage” in advocating a
“sewage-free natural environment,” notes that groundwater
tainted by effluent in southern California has not been shown
to have had adverse human health effects. That response does
not address the risk posed by this project: that is, direct expo-
sure to, and possible ingestion of, snow made from undiluted
treated sewage effluent.

   A second response purports to answer a question about who
would bear liability for illnesses caused by the treated sewage
effluent. The response states that the treated sewage effluent
is “very strictly controlled,” “acceptable for unrestricted body
contact,” and “authorized for artificial snowmaking for skiing
by ADEQ.” Not only does the response fail to answer the lia-
bility question posed; the response also fails to address the
fact that the ADEQ has specifically disapproved human inges-
tion of treated sewage effluent.

   The third response is to a question about why warning signs
are necessary if the reclaimed water is not harmful. The FEIS
states, hypothetically: “The extent to which reclaimed water
is or is not a human health and safety concern would depend
on many factors . . . . Poorly or partially treated wastewater
could give rise to infectious disease. On the other hand, it is
technically and economically feasible to treat wastewater to
acceptable drinking water quality.” As above, this is a non-
responsive answer. While it may be true that “it is technically
and economically feasible” to treat wastewater to the point
where it meets drinking water standards, the fact in this case
is that the treated sewage effluent proposed for use is not
treated to meet standards for potable water. The FEIS then
explains that the signs are required under Arizona law: “In
direct response to the comment, it should be realized that
there are many sites in Arizona where a lower quality of
reclaimed water is used for irrigation. The law protects the
public (e.g., golfers and farm workers) in the hot desert
regions that might otherwise believe the water is potable.”
                    NAVAJO NATION v. USFS                  2883
This response does not address the risk that children or adults
might also think the snow may be ingested. Further, in refer-
ring to the need to guard against ingestion of “lower quality”
reclaimed water, the answer implies (incorrectly) that the arti-
ficial snow would be made of potable water.

   The fourth response follows three combined questions: (1)
whether signs would be posted to warn that “reclaimed water”
has been used to make the artificial snow; (2) how much
exposure to the snow would be sufficient to make a person ill;
and (3) how long it would take to see adverse effects on plants
and animals downstream. The response to these questions is
four sentences long. It states that signs would be posted, but
it does not say how numerous or how large the signs would
be. It then summarizes the treatment the sewage would
undergo. The final sentence asserts: “In terms of microbiolog-
ical and chemical water quality, the proposed use of reclaimed
water for snowmaking represents a low risk of acute or
chronic adverse environmental impact to plants, wildlife, and
humans.” The response does not answer the specific and
highly relevant question: How much direct exposure to the
artificial snow is safe? Nor does the response provide any
analysis of the extent of the likely “exposure,” including the
likelihood that children or adults would accidentally or inten-
tionally ingest the snow made from non-potable treated sew-
age effluent.

   The fifth response is on the last page of responses to com-
ments. The Forest Service in its brief does not call attention
to this response, perhaps because the Service recognizes its
inadequacy. The questions and response are:

    In areas where reclaimed water is presently used,
    there are signs posted to warn against consump-
    tion of the water. Will these signs be posted at the
    Snowbowl? If so, how will that keep children
    from putting snow in there [sic] mouths or acci-
2884                 NAVAJO NATION v. USFS
    dentally consuming the snow in the case of a
    wreck?

    There will be signs posted at Snowbowl informing
    visitors of the use of reclaimed water as a snowmak-
    ing water source. Much like areas of Flagstaff where
    reclaimed water is used, it is the responsibility of the
    visitor or the minor’s guardian to avoid consuming
    snow made with reclaimed water. It is important to
    note that machine-produced snow would be mixed
    and therefore diluted with natural snow decreasing
    the percentage of machine-produced snow within the
    snowpack. Because ADEQ approved the use of
    reclaimed water, it is assumed different types of inci-
    dental contact that could potentially occur from use
    of class A reclaimed water for snowmaking were
    fully considered.

(Emphasis added.)

   There are several problems with this response. First, the
response does not assess the risk that children will eat the arti-
ficial snow. Stating that it is the parents’ responsibility to pre-
vent their children from doing so neither responds to the
question whether signs would prevent children from eating
snow, nor addresses whether ingesting artificial snow would
be harmful. Second, the Forest Service’s assumption that the
ADEQ’s approval means the snow must be safe for ingestion
is inconsistent with that same agency’s regulations, which are
designed to prevent human ingestion. Third, the assumption
that the ADEQ actually analyzed the risk of skiers ingesting
the treated sewage effluent snow is not supported by any evi-
dence in the FEIS (or elsewhere in the administrative record).
Finally, the Forest Service’s answer is misleading in stating
that the treated sewage effluent will be “diluted.” The artifi-
cial snow would itself be made entirely from treated sewage
effluent and would only be “mixed and therefore diluted”
with natural snow insofar as the artificial snow intermingles
                     NAVAJO NATION v. USFS                    2885
with a layer of natural snow. During a dry winter, there may
be little or no natural snow with which to “dilute” the treated
sewage effluent.

   In addition to directing our attention to the responses
above, Appellees further contend that the FEIS “sets forth rel-
evant mitigation measures” to “the possibility that someone
may ingest snow.” Although Appellees do not specify the
“relevant mitigation measures” to which they refer, the only
mitigation measure mentioned in the FEIS is the requirement
under Arizona law that the Snowbowl post signs “so the pub-
lic is informed that reclaimed water is in use and that no one
should drink from the system.” Ariz. Admin. Code § R18-9-
704(H) (2005). This “mitigation measure” is not listed along
with the fifty-five mitigation measures catalogued in a table
in the FEIS. Cf. 40 C.F.R. § 1502.14 (f) (requiring agencies
to include “appropriate mitigation measures” in the EIS’s
description of the proposal and its alternatives). The mea-
sure’s omission from the FEIS table is hardly surprising, how-
ever, given that the FEIS does not address as an
environmental impact the risk to human health from the possi-
ble ingestion of artificial snow made from treated sewage
effluent.

   Our role in reviewing the FEIS under the APA is not to
second-guess a determination by the Forest Service about
whether artificial snow made from treated sewage effluent
would be ingested and, if so, whether such ingestion would
threaten human health. We are charged, rather, with evaluat-
ing whether the FEIS contains “a reasonably thorough discus-
sion of the significant aspects of the probable environmental
consequences.” Ctr. for Biological Diversity, 349 F.3d at
1166 (quotation marks omitted). An agency preparing an EIS
is required to take a “hard look” that “[a]t the least . . . encom-
passes a thorough investigation into the environmental
impacts of an agency’s action and a candid acknowledgment
of the risks that those impacts entail.” Nat’l Audubon Soc’y v.
Dep’t of the Navy, 422 F.3d 174, 185 (4th Cir. 2005) (citing
2886                NAVAJO NATION v. USFS
Robertson, 490 U.S. at 350 (stating that NEPA requires envi-
ronmental costs to be “adequately identified and evaluated”)).
A proper NEPA analysis will “foster both informed decision-
making and informed public participation.” Churchill, 276
F.3d at 1071 (quoting Block, 690 F.2d at 761).

   [20] We conclude that the Forest Service has not provided
a “reasonably thorough discussion” of any risks posed by
human ingestion of artificial snow made from treated sewage
effluent or articulated why such a discussion is unnecessary,
has not provided a “candid acknowledgment” of any such
risks, and has not provided an analysis that will “foster both
informed decision-making and informed public participation.”
We therefore hold that the FEIS does not satisfy NEPA with
respect to the risks of ingesting artificial snow.

              B.   Consideration of Alternatives

   Appellants Norris Nez, Bill “Bucky” Preston, and the
Hualapai Tribe (“Hualapai Appellants” or “Appellants”)
claim that the Forest Service failed to consider a reasonable
range of alternatives in the FEIS. They claim that the range
of alternatives falls short because the Forest Service took
actions that foreclosed considering other alternatives, and
because the Service failed to consider the alternative of drill-
ing for fresh water.

   [21] NEPA provides that an EIS must contain a discussion
of “alternatives to the proposed action,” and that federal agen-
cies must “study, develop, and describe appropriate alterna-
tives to recommended courses of action in any proposal which
involves unresolved conflicts concerning alternative uses of
available resources.” 42 U.S.C. § 4332(2)(C)(iii), (E). This
requirement is “the heart of the environmental impact state-
ment.” 40 C.F.R. § 1502.14.

  Project alternatives derive from an EIS’s “Purpose and
Need” section, which briefly specifies “the underlying pur-
                    NAVAJO NATION v. USFS                  2887
pose and need to which the agency is responding in proposing
the alternatives including the proposed action.” Id. § 1502.13.
“The stated goal of a project necessarily dictates the range of
‘reasonable’ alternatives and an agency cannot define its
objectives in unreasonably narrow terms.” City of Carmel-by-
the-Sea v. U.S. Dep’t of Transp., 123 F.3d 1142, 1155 (9th
Cir. 1997). Federal agencies must present the environmental
impacts of the proposal in comparative form, “[r]igorously
explore and objectively evaluate all reasonable alternatives,”
and “briefly discuss” the reasons for eliminating any alterna-
tives from detailed study. 40 C.F.R. § 1502.14(a). “The rule
of reason guides both the choice of alternatives as well as the
extent to which the EIS must discuss each alternative.” City
of Sausalito v. O’Neill, 386 F.3d 1186, 1207 (9th Cir. 2004)
(alteration and internal punctuation omitted).

   The regulations further provide that “[a]gencies shall not
commit resources prejudicing selection of alternatives before
making a final decision.” 40 C.F.R. § 1502.2(f); see also id.
§ 1506.1. An EIS “shall serve as the means of assessing the
environmental impact of proposed agency actions, rather than
justifying decisions already made.” Id. § 1502.2(g). However,
agencies shall also “[i]dentify the agency’s preferred alterna-
tive or alternatives, if one or more exists, in the draft state-
ment and identify such alternative in the final statement
unless another law prohibits the expression of such a prefer-
ence.” Id. § 1502.14(e). We have interpreted this regulation to
mean that “an agency can formulate a proposal or even iden-
tify a preferred course of action before completing an EIS.”
Ass’n of Pub. Agency Customers, Inc. v. Bonneville Power
Admin., 126 F.3d 1158, 1185 (9th Cir. 1997).

  The FEIS and ROD define the Proposed Action’s “Purpose
and Need” as follows:

    Purpose #1
    To ensure a consistent and reliable operating sea-
    son, thereby maintaining the economic viability of
2888                NAVAJO NATION v. USFS
    the Snowbowl, and stabilizing employment levels
    and winter tourism within the local community.

    ....

    Purpose #2:
    To improve safety, skiing conditions, and recre-
    ational opportunities, bringing terrain and infra-
    structure into balance with current use levels.

The district court upheld this statement of purpose and need
because it responds to documented needs and because it fits
with both the forest plan for the Coconino National Forest and
the Forest Service’s multiple-use mandate. 408 F. Supp. 2d at
873-74. Although Appellants note that an agency does not
have unlimited discretion to define the purpose and need for
a project, they do not appeal this ruling.

  Rather, the Hualapai Appellants argue that certain pre-
scoping memoranda and notes demonstrate that the Forest
Service took actions that foreclosed the consideration of a rea-
sonable range of alternatives. They largely base their argu-
ment on the scripted “Key Messages” contained in the Forest
Service’s June 2002 “Tribal Consultation Plan”:

    1. We [the Forest Service] think it’s a good idea, and
    we already know you [tribes] don’t approve of it, but
    Snowbowl is there & isn’t going away.

    ....

    6.   Upgrade can’t be done without snowmaking

    7.   Recycled water IS clean, disease-free.

    8.   How can YOU help US make it work ???

Appellants argue that another June 2002 talking points memo-
randum also supports the notion that the adoption of the pro-
                    NAVAJO NATION v. USFS                   2889
posed action was predetermined, quoting part of the scripted
response contained in the memorandum: “Once we accept the
proposal, we DO support it . . . .” Further, they point to a note
from a Forest Service meeting in August 2002, before the
Snowbowl had officially submitted its proposal: “[W]e are all
ambassadors of this [project] and need to provide the same
messages.”

   Despite what these scripted responses written early in the
process suggest, the balance of the administrative record suf-
ficiently demonstrates that the Forest Service had not fore-
closed all consideration of alternatives. Among the five
“objectives” listed in the Tribal Consulation Plan are “Get
ideas on possible mitigating measures” and “Are there any
additional tribal concerns we don’t already know about.” The
full sentence from the other talking points memorandum indi-
cates that the Forest Service had not settled on any particular
proposal: “Once we accept the proposal, we DO support it —
That’s why we want your input now so hopefully we can have
a proposal we can all work with.” The Forest Service was
entitled to have in mind a preferred course of action in
advance, see Ass’n of Pub. Agency Customers, 126 F.3d at
1185, and Appellants are unable to point to substantial evi-
dence indicating that the Forest Service impermissibly “com-
mit[ted] resources prejudicing selection of alternatives before
making a final decision.” 40 C.F.R. § 1502.2(f) (emphasis
added).

   Appellants also argue that the Forest Service failed ade-
quately to consider fresh water drilling as an alternative to the
use of treated sewage effluent for snowmaking. The Forest
Service (but not the Snowbowl) argues that the doctrine of
exhaustion bars this claim because Appellants did not raise
the issue during the comment period or in their administrative
appeal. The record contradicts the Forest Service. In his
administrative appeal, Appellant Preston argued that the FEIS
was inadequate because “an alternative was suggested for the
2890                NAVAJO NATION v. USFS
use of freshwater instead of reclaimed water for snowmaking,
but was summarily dismissed.”

   [22] Appellants concede that the FEIS briefly addresses
multiple alternatives to using the treated sewage effluent.
They object, however, that the Forest Service relied on the
Snowbowl’s studies on the feasibility of water alternatives
without conducting sufficient independent investigation and
without disclosing sufficient information to the public to chal-
lenge the Snowbowl’s studies. They further argue that the
Forest Service’s “assertions regarding economic and technical
difficulties are questionable given the exorbitantly high costs
($19,733,000) and the technical difficulty of the selected
alternative.” To the contrary, the fact the Snowbowl is appar-
ently willing to incur such costs supports the Forest Service’s
conclusion that the alternative sources of water were not rea-
sonable. In justifying its elimination of the potable water
alternative, the Forest Service cited “logistical and economic
considerations and water availability research,” as well as
“environmental and political issues.” Appellants have not
shown that a fresh water alternative was reasonable in the
middle of the northern Arizona desert, and that the relatively
brief treatment in the FEIS was therefore inadequate. Thus,
although the Forest Service’s discussion was indeed brief,
Appellants have not shown that the discussion was inadequate
under 40 C.F.R. § 1502.14(a).

          C.   Disclosure of Scientific Viewpoints

   The Navajo Appellants claim that the Forest Service failed
to discuss and consider adequately the scientific viewpoint of
Dr. Paul Torrence. Dr. Torrence criticized the draft EIS for
approving the proposal despite the risks posed by endocrine-
disrupting chemicals present in treated sewage effluent.

   [23] Regulations require an agency preparing an FEIS to
“assess and consider comments both individually and collec-
tively,” to respond to the comments, and to state its responses
                    NAVAJO NATION v. USFS                   2891
in the FEIS. 40 C.F.R. § 1503.4(a). Although the agency need
not “set forth at full length the views with which it disagrees,”
Block, 690 F.2d at 773, the agency must “discuss at appropri-
ate points in the [FEIS] any responsible opposing view which
was not adequately discussed in the draft statement.” 40
C.F.R. § 1502.9(b). Ordinarily, the agency must attach to the
FEIS “all substantive comments . . . whether or not the com-
ment is thought to merit individual discussion.” Id.
§ 1503.4(b). However, if comments have been “exceptionally
voluminous,” summaries suffice. Id. Under some circum-
stances, an agency’s response to a comment need not be given
in the main body of the FEIS and may instead be contained
in a separate “comments and responses” section. Those cir-
cumstances arise when “many of the critical comments
prompted revisions in the body, [the agency] discussed in the
body all of the environmental problems to which the com-
ments were addressed, and [the agency] provided thoughtful
and well-reasoned responses to most of the critical com-
ments.” Ore. Natural Res. Council v. Marsh, 832 F.2d 1489,
1498-99 (9th Cir. 1987) (as amended), rev’d on other
grounds, 490 U.S. 360 (1989).

   In Center for Biological Diversity, we held that an FEIS
was inadequate because it failed “to disclose responsible sci-
entific opposition to the conclusion upon which it [was]
based.” 349 F.3d at 1160. The FEIS in that case evaluated
amendments to a forest management plan, prompted by the
need to protect the habitat of the northern goshawk. Id. at
1160-61. The alternatives evaluated were all based upon the
scientific conclusion that the birds were “habitat generalists.”
Id. at 1160. The agency received comments from multiple
federal and state agencies citing studies indicating that the
birds were not habitat generalists, and that therefore the pro-
posed plans would be inadequate. Id. at 1162-63. The agency
responded to the comments directly via letter, but did not dis-
close or respond to them specifically in the FEIS. Id. at 1161-
62. Rather, the FEIS merely acknowledged in a summary
comment that “[a] few commenters expressed concern that the
2892                NAVAJO NATION v. USFS
proposed standards and guidelines for the . . . northern gos-
hawk are grossly inadequate to protect the birds,” and
responded that “[t]he guidelines have been developed over
several years using the best information and scientific review
available” and could “easily be updated through future
amendments.” Id. at 1163 (alterations in original, quotation
marks omitted). We held that the Forest Service was required
to disclose and respond to the comments in the FEIS itself,
because the comments were undisputedly “responsible oppos-
ing scientific viewpoints,” and because the FEIS’s recommen-
dations undisputedly “rest[ed] upon the Service’s habitat
generalist conclusion.” Id. at 1167.

   The FEIS in this case is unlike the FEIS in Center for Bio-
logical Diversity. The comments of Dr. Torrence alleged by
Appellants to have been inadequately treated in the FEIS do
not represent an undisclosed opposing viewpoint to which the
Forest Service failed to respond openly in the FEIS. Appel-
lants object to the district court’s characterization of Dr. Tor-
rence’s comments as “all . . . variations of the same
allegation: that the agency failed to fully consider the range
of implications of endocrine disruptors.” 408 F. Supp.2d at
877. They assert that Dr. Torrence’s comments raise a broader
set of issues that the FEIS fails to disclose and discuss. Yet
the district court’s characterization is accurate because Dr.
Torrence’s comments all concern endocrine disruptors.

   [24] The FEIS discloses, discusses, and responds to the
substance of Dr. Torrence’s comments. The main body of the
FEIS contains a subsection on endocrine disruptors that cites
a range of research and discusses the growing scientific and
governmental concern about their effects on wildlife, humans,
and the environment. The FEIS also discloses and discusses
studies done on endocrine disruptors in the treated sewage
effluent proposed for use in this case. The FEIS contains a
table listing the amounts of suspected disruptors measured in
the water and briefly summarizes a study of its effect on vari-
ous animals in experiments conducted by a Northern Arizona
                   NAVAJO NATION v. USFS                  2893
University professor, Dr. Catherine Propper. The FEIS com-
ments that the concentrations of the suspected endocrine dis-
ruptors are significantly lower in the Rio de Flag water than
in other waste water also measured in the study, and that “the
proposed use of reclaimed water for snowmaking . . . will not
result in comparable environmental exposure as investigated
by Dr. Propper.” Thus, although the FEIS takes a more san-
guine view of the risk than does Dr. Torrence, the main body
of the FEIS discloses to the public, and makes clear that the
Forest Service considered, the risk posed by endocrine disrup-
tors.

            D.   Impact on the Regional Aquifer

   The Navajo Appellants claim that the FEIS inadequately
considers the environmental impact of diverting the treated
sewage effluent from Flagstaff’s regional aquifer. The Forest
Service argues that this claim was not exhausted in the admin-
istrative process. We disagree. Several comments raised the
issue of diverting water that would have gone into the
regional aquifer, including a comment by the Center for Bio-
diversity and the Flagstaff Activist Network, as well as a
lengthy analysis submitted by the Sierra Club. Appellants’
administrative appeal explicitly incorporated and reasserted
by reference the submissions of these organizations. Thus,
“taken as a whole,” their appeal “provided sufficient notice to
the [agency] to afford it the opportunity to rectify the viola-
tions that the plaintiffs alleged.” Native Ecosystems Council,
304 F.3d at 899.

   On the merits, Appellants claim that the FEIS inadequately
considers the environmental impact of diverting the treated
sewage effluent wastewater from the aquifer. Currently, dur-
ing the winter when there is little demand for “reclaimed
water” for irrigation and other uses, the treated sewage efflu-
ent is pumped into the Rio de Flag, where it is diluted with
fresh water and percolates into the underground regional aqui-
fer. Much of the effluent used to make artificial snow would
2894                NAVAJO NATION v. USFS
eventually make its way back to the aquifer, but some water
would be lost to sublimation and evaporation. The FEIS con-
tains extensive analysis on the question of the impact of this
water loss on the recharge of the regional aquifer; subchapter
3H, discussed above, is largely devoted to the subject.

   Nevertheless, Appellants argue that the FEIS does not ade-
quately address the cumulative impact on the aquifer caused
by diverting the water. First, they argue that the analysis is
inadequate because the FEIS states that the study area of the
watershed analysis is limited to the Hart Prairie Watershed
and the Agassiz Subwatershed, an area that does not include
the location where the treatment plant discharges the treated
sewage effluent into the Rio de Flag. Therefore, they argue,
the analysis fails to consider the impact on the regional aqui-
fer caused by diverting the effluent from the Rio de Flag.
However, the analysis of environmental impacts is plainly not
limited to the designated “study area.” Immediately after
describing the parameters of the “study area” for the water-
shed analysis, the FEIS identifies as one of the cumulative
effects to be analyzed the “potential long-term effects on the
regional aquifer from diversions of reclaimed water for snow-
making.”

   Second, Appellants argue that the FEIS is inadequate,
because the Forest Service “refused” to consider the impact of
the wastewater diversion. They point to two portions of the
FEIS that do, indeed, disclaim responsibility for analyzing the
impact on the regional aquifer. The FEIS states that, due to an
Arizona Supreme Court decision holding that cities can sell
wastewater, “the authority of the city to provide reclaimed
water to the Snowbowl is not subject to decision by the Forest
Service and is therefore not within the jurisdictional purview
of this analysis.” In the comments and responses portion of
the FEIS, the Forest Service reiterates, “The City has the legal
right to put the reclaimed water to any reasonable use they see
fit and is the responsible entity to determine the most suitable
and beneficial use of reclaimed water.”
                     NAVAJO NATION v. USFS                     2895
   [25] Nevertheless, the FEIS contains some analysis of the
environmental impact of the diversion on the regional aquifer.
After stating that the issue “extends well beyond the scope of
the EIS” and “is provided as general information but will not
be specifically considered in selecting an alternative,” the
Forest Service provides a quantitative analysis concluding
that the snowmaking would “result in an estimated net aver-
age reduction in groundwater recharge to the regional aquifer
of . . . . slightly less than two percent of the City of Flagstaff’s
total annual water production.” Ultimately, the FEIS con-
cludes that the cumulative impact is “negligible for overall
change in aquifer recharge.” Despite the odd and backhanded
way in which it is presented, we conclude that the analysis in
the FEIS is a “reasonably thorough discussion” of the issue.
Ctr. for Biological Diversity, 349 F.3d at 1166.

               E.   Social and Cultural Impacts

   The Hopi Appellants argue that the FEIS inadequately ana-
lyzes the social and cultural impacts of the proposed action on
the Hopi people. NEPA requires agencies to “utilize a system-
atic, interdisciplinary approach which will insure the inte-
grated use of the natural and social sciences and the
environmental design arts in planning and in decisionmaking
which may have an impact on man’s environment.” 42 U.S.C.
§ 4332(2)(A). Agencies must “identify and develop methods
and procedures . . . which will insure that presently unquanti-
fied environmental amenities and values may be given appro-
priate consideration in decisionmaking along with economic
and technical considerations.” Id. § 4332(2)(B). Finally, agen-
cies must prepare an EIS for “major Federal actions signifi-
cantly affecting the quality of the human environment.” Id.
§ 4332(2)(C). The regulations define “human environment”
broadly to “include the natural and physical environment and
the relationship of people with that environment,” and note
that “[w]hen an [EIS] is prepared and economic or social and
natural or physical environmental effects are interrelated, then
the [EIS] will discuss all of these effects on the human envi-
2896                NAVAJO NATION v. USFS
ronment.” 40 C.F.R. § 1508.14. The “effects” that should be
discussed include “aesthetic, historic, cultural, economic,
social, or health” effects, “whether direct, indirect, or cumula-
tive.” Id. § 1508.8.

   [26] The FEIS addresses the “human environment” through
lengthy discussions of the relationship of the Hopi and others
to the San Francisco Peaks and the impact of the proposed
action on those relationships. The FEIS acknowledges that “it
is difficult to be precise in the analysis of the impact of the
proposed undertaking on the cultural and religious systems on
the Peaks, as much of the information stems from oral histo-
ries and a deep, underlying belief system of the indigenous
peoples involved.” Nevertheless, the FEIS makes clear that
the Forest Service conducted an extensive analysis of the
issue, drawing from existing literature and extensive consulta-
tion with the affected tribes. The FEIS describes at length the
religious beliefs and practices of the Hopi and the Navajo and
the “irretrievable impact” the proposal would likely have on
those beliefs and practices. The Forest Service has thus satis-
fied its obligations under NEPA to discuss the effects of the
proposed action on the human environment.

                        F.   Conclusion

   For the foregoing reasons, we hold that the FEIS was inad-
equate with respect to its discussion of the risks posed by pos-
sible human ingestion of artificial snow made from treated
sewage effluent. We hold that the FEIS was adequate in the
four other respects challenged.

           V.   National Historic Preservation Act

   [27] If a proposed undertaking will have an effect on his-
toric properties to which Indian tribes attach religious and cul-
tural significance, the National Historic Preservation Act
(“NHPA”) requires the federal agency to consult with the
affected tribes before proceeding. See 16 U.S.C.
                   NAVAJO NATION v. USFS                   2897
§§ 470a(d)(6), 470f; 36 C.F.R. §§ 800.1 et seq. Under NHPA
regulations, “[c]onsultation means the process of seeking, dis-
cussing, and considering the views of other participants, and,
where feasible, seeking agreement with them.” 36 C.F.R.
§ 800.16(f).

   The Hopi Appellants argue that the Forest Service did not
meaningfully consult with them. They concede that the Forest
Service “sought tribal consultation on the religious and cul-
tural significance of the Peaks, and provided a reasonable
opportunity for the tribes to participate in the process,” but
they assert that those consultations were meaningless because
the Forest Service prejudged the matter.

   The evidence proffered by the Hopi Appellants does not
support their claim. Their primary evidence is a letter from
the Forest Service to the tribe. The Hopi Appellants contend
that the letter shows that the proposal ultimately approved in
the FEIS was preordained. The letter informs the Hopi that
the owner of the Snowbowl is working on a draft proposal,
states that the Forest Service believes the Hopi should be
involved in the development of this proposal, and asks for
input on “how the interests and concerns of the Hopi people
might best be addressed” before the Forest Service accepts the
proposal.

  The Hopi Appellants specifically object to the following
paragraph in the letter:

    The proposed development of the Arizona Snow-
    bowl was the subject of a bitter lawsuit in 1981.
    Hopefully by involving the Hopi Tribe in planning
    the development this time, we can all avoid expen-
    sive and time-consuming litigation. However, the
    result of the 1981 lawsuit was a legal decision that
    allows the development of the Arizona Snowbowl
    and the construction of a number of facilities. The
    Snowbowl now wishes to complete the development,
2898                NAVAJO NATION v. USFS
    and it is important to stress that the scope of the pro-
    posal, with a few exceptions, is within the concept
    approved by the court decision. It is also important
    to note that all facilities will stay within the permit-
    ted area.

They argue that this letter “informed [them] at the outset that,
based on its incorrect reading of an earlier court decision
(apparently referring to Wilson v. Block, 708 F.2d 735 (D.C.
Cir. 1983)), the Forest Service had no discretion to disapprove
the development proposed by the Snowbowl, thus making the
Proposed Action a foregone conclusion.”

   The Hopi Appellants’ interpretation misconstrues the For-
est Service’s letter. The letter indicates that most but not all
of the proposal is within the scope of the 1979 decision — the
“few exceptions” include snowmaking. Hence the letter spe-
cifically notes that the Snowbowl intends to introduce new
components never addressed in Wilson, thus implying that the
Forest Service need not accept the proposal. This implication
is supported by the letter’s suggestion that consultation might
avoid a court battle. Thus, while the Forest Service’s letter
signals receptiveness to the Snowbowl’s proposal, it does not
demonstrate that the Forest Service failed to meaningfully
consult with the Hopi.

   [28] The Hopi also incorporate by reference the evidence
that the Hualapai presented in their argument discussed above
that the Forest Service took actions that foreclosed the consid-
eration of a reasonable range of alternatives. However,
because of the extensive record of consultation undertaken by
the Forest Service in this case, we agree with the district court
that “[a]lthough the consultation process did not end with a
decision the tribal leaders supported, this does not mean that
the Forest Service’s consultation process was substantively
and procedurally inadequate.” 408 F. Supp. 2d at 879 n.11;
see also id. at 879-80 & n.11 (describing the scope of the con-
sultations in detail).
                    NAVAJO NATION v. USFS                  2899
                       VI.   Conclusion

   In sum, we reverse the district court on two grounds. First,
we hold that the Forest Service’s approval of the proposed
expansion of the Snowbowl, including the use of treated sew-
age effluent to make artificial snow, violates RFRA. Second,
we hold that the Forest Service’s FEIS does not fulfil its obli-
gations under NEPA because it neither reasonably discusses
the risks posed by the possibility of human ingestion of artifi-
cial snow made from treated sewage effluent nor articulates
why such discussion is unnecessary. We affirm the district
court’s grant of summary judgment on Appellants’ remaining
four NEPA claims and on their NHPA claim.

  AFFIRMED in part, REVERSED in part, and
REMANDED. The parties shall bear their own costs on
appeal.
