National Ass'n of Home Builders v. Defenders of Wildlife

(Slip Opinion) OCTOBER TERM, 2006 1

Syllabus

NOTE: Where it is feasible, a syllabus (headnote) will be released, as is
being done in connection with this case, at the time the opinion is issued.
The syllabus constitutes no part of the opinion of the Court but has been
prepared by the Reporter of Decisions for the convenience of the reader.
See United States v. Detroit Timber & Lumber Co., 200 U. S. 321, 337.

SUPREME COURT OF THE UNITED STATES

Syllabus

NATIONAL ASSOCIATION OF HOME BUILDERS

ET AL. v. DEFENDERS OF WILDLIFE ET AL.

CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR
THE NINTH CIRCUIT

No. 06–340. Argued April 17, 2007—Decided June 25, 2007*
Under the Clean Water Act (CWA), petitioner Environmental Protec
tion Agency (EPA) initially administers each State’s National Pollu
tion Discharge Elimination System (NPDES) permitting program,
but CWA §402(b) provides that the EPA “shall approve” transfer of
permitting authority to a State upon application and a showing that
the State has met nine specified criteria. Section 7(a)(2) of the En
dangered Species Act of 1973 (ESA) requires federal agencies to con
sult with agencies designated by the Secretaries of Commerce and
the Interior to “insure” that a proposed agency action is unlikely to
jeopardize an endangered or threatened species. The Fish and Wild
life Service (FWS) and the National Marine Fisheries Service
(NMFS) administer the ESA. Once a consultation process is com
plete, a written biological opinion is issued, which may suggest alter
native actions to protect a jeopardized species or its critical habitat.
When Arizona officials sought EPA authorization to administer the
State’s NPDES program, the EPA initiated consultation with the
FWS to determine whether the transfer would adversely affect any
listed species. The FWS regional office wanted potential impacts
taken into account, but the EPA disagreed, finding that §402(b)’s
mandatory nature stripped it of authority to disapprove a transfer
based on any other considerations. The dispute was referred to the
agencies’ national offices for resolution. The FWS’s biological opinion
concluded that the requested transfer would not jeopardize listed
species. The EPA concluded that Arizona had met each of §402(b)’s
——————
* Together with No. 06–549, Environmental Protection Agency v. De
fenders of Wildlife et al., also on certiorari to the same court.
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nine criteria and approved the transfer, noting that the biological
opinion had concluded the consultation “required” by ESA §7(a)(2).
Respondents sought review in the Ninth Circuit, petitioner National
Association of Home Builders intervened, and part of respondent De
fenders of Wildlife’s separate action was consolidated with the suit.
The court held that the EPA’s transfer approval was arbitrary and
capricious because the EPA had relied on contradictory positions re
garding its §7(a)(2) responsibilities during the administrative proc
ess. Rather than remanding the case for the agency to explain its de
cision, however, the court reviewed the EPA’s substantive
construction of the statutes. It did not dispute that Arizona had met
CWA §402(b)’s nine criteria, but nevertheless concluded that ESA
§7(a)(2) required the EPA to determine whether its transfer decision
would jeopardize listed species, in effect adding a tenth criterion.
The court dismissed the argument that the EPA’s approval was not
subject to §7(a)(2) because it was not a “discretionary action” under
50 CFR §402.03, §7(a)(2)’s interpretative regulation. The court thus
vacated the EPA’s transfer decision.
Held:
1. The Ninth Circuit’s determination that the EPA’s action was ar
bitrary and capricious is not fairly supported by the record. This
Court will not vacate an agency’s decision under the arbitrary and
capricious standard unless the agency “relied on factors which Con
gress had not intended it to consider, entirely failed to consider an
important aspect of the problem, offered an explanation for its deci
sion that runs counter to the evidence before the agency, or is so im
plausible that it could not be ascribed to a difference in view or the
product of agency expertise.” Motor Vehicle Mfrs. Assn. of United
States, Inc. v. State Farm Mut. Automobile Ins. Co., 463 U. S. 29, 43.
Here, the Ninth Circuit concluded that the EPA’s decision was inter
nally inconsistent in its statements during the review process. Fed
eral courts ordinarily are empowered to review only an agency’s final
action, and the fact that a local agency representative’s preliminary
determination is later overruled at a higher agency level does not
render the decisionmaking process arbitrary and capricious. The
EPA’s final approval notice stating that §7(a)(2)’s required consulta
tion process had been concluded may be inconsistent with its previ
ously expressed position—and position in this litigation—that
§7(a)(2)’s consultation requirement is not triggered by a §402 transfer
application, but that is not the type of error requiring a remand. By
the time the statement was issued, the EPA and FWS had already
consulted, and the question whether that consultation had been re
quired was not germane to the final agency decision. Thus, this
Court need not further delay the permitting authority transfer by
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remanding to the agency for clarification. Respondents suggest that
the EPA nullified their right to participate in the application proceed
ings by altering its legal position during the pendency of the transfer
decision and its associated litigation, but they do not suggest that
they were deprived of their right to comment during the comment pe
riod made available under the EPA’s regulations. Pp. 10–14.
2. Because §7(a)(2)’s no-jeopardy duty covers only discretionary
agency actions, it does not attach to actions (like the NPDES permit
ting transfer authorization) that an agency is required by statute to
undertake once certain specified triggering events have occurred.
Pp. 14–25.
(a) At first glance the legislative commands here are irreconcil
able. Section 402(b)’s “shall approve” language is mandatory and its
list exclusive; if the nine specified criteria are satisfied, the EPA does
not have the discretion to deny a transfer application. Section
7(a)(2)’s similarly imperative language would literally add a tenth
criterion to §402(b). Pp. 14–15.
(b) While a later enacted statute (such as the ESA) can some
times operate to amend or even repeal an earlier statutory provision
(such as the CWA), “repeals by implication are not favored” and will
not be presumed unless the legislature’s intention “to repeal [is] clear
and manifest.” Watt v. Alaska, 451 U. S. 259, 267. Statutory repeal
will not be inferred “unless the later statute ‘ “expressly contradict[s]
the original act” ’ or such a construction ‘ “is absolutely necessary [to
give the later statute’s words] any meaning at all.” ’ ” Traynor v.
Turnage, 485 U. S. 535, 548. Otherwise, “a statute dealing with a
narrow, precise, and specific subject is not submerged by a later en
acted statute covering a more generalized spectrum.” Radzanower v.
Touche Ross & Co., 426 U. S. 148, 153. The Ninth Circuit’s reading
of §7(a)(2) would effectively repeal §402(b)’s mandate that the EPA
“shall” issue a permit whenever all nine exclusive statutory prerequi
sites are met. Section 402(b) does not just set minimum require
ments; it affirmatively mandates a transfer’s approval, thus operat
ing as a ceiling as well as a floor. By adding an additional criterion,
the Ninth Circuit raises that floor and alters the statute’s command.
Read broadly, the Ninth Circuit’s construction would also partially
override every federal statute mandating agency action by subjecting
such action to the further condition that it not jeopardize listed spe
cies. Pp. 15–17.
(c) Title 50 CFR §402.03, promulgated by the NMFS and FWS
and applying §7(a)(2) “to all actions in which there is discretionary
Federal involvement or control” (emphasis added), harmonizes the
CWA and ESA by giving effect to the ESA’s no-jeopardy mandate
whenever an agency has discretion to do so, but not when the agency
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is forbidden from considering such extrastatutory factors. The Court
owes “some degree of deference to the Secretary’s reasonable inter
pretation” of the ESA, Babbitt v. Sweet Home Chapter, Communities
for Great Ore., 515 U. S. 687, 703. Deference is not due if Congress
has made its intent “clear” in the statutory text, Chevron U. S. A. Inc.
v. Natural Resources Defense Council, Inc., 467 U. S. 837, 842, but “if
the statute is silent or ambiguous . . . the question . . . is whether the
agency’s answer is based on a permissible construction of the stat
ute,” id., at 843. Because the “meaning—or ambiguity—of certain
words or phrases may only become evident . . . in context,” FDA v.
Brown & Williamson Tobacco Corp., 529 U. S. 120, 132, §7(a)(2) must
be read against the statutory backdrop of the many mandatory
agency directives whose operation it would implicitly abrogate or re
peal were it construed as broadly as the Ninth Circuit did below.
Such a reading leaves a fundamental ambiguity. An agency cannot
simultaneously obey the differing mandates of ESA §7(a)(2) and CWA
§402(b), and consequently the statutory language—read in light of
the canon against implied repeals—does not itself provide clear guid
ance as to which command must give way. Thus, it is appropriate to
look to the implementing agency’s expert interpretation, which har
monizes the statutes by applying §7(a)(2) to guide agencies’ existing
discretionary authority, but not reading it to override express statu
tory mandates. This interpretation is reasonable in light of the stat
ute’s text and the overall statutory scheme and is therefore entitled
to Chevron deference. The regulation’s focus on “discretionary” ac
tions accords with the commonsense conclusion that, when an agency
is required to do something by statute, it simply lacks the power to
“insure” that such action will not jeopardize listed species. The basic
principle of Department of Transportation v. Public Citizen, 541 U. S.
752—that an agency cannot be considered the legal “cause” of an ac
tion that it has no statutory discretion not to take, id., at 770—
supports the reasonableness of the FWS’s interpretation. Pp. 17–22.
(d) Respondents’ contrary position is not supported by TVA v.
Hill, 437 U. S. 153, which had no occasion to answer the question
presented in these cases. Pp. 22–24.
(e) Also unavailing is the argument that EPA’s decision to trans
fer NPDES permitting authority to Arizona represented a “discre
tionary” agency action. While the EPA may exercise some judgment
in determining whether a State has shown that it can carry out
§402(b)’s enumerated criteria, the statute clearly does not grant it
the discretion to add another entirely separate prerequisite to that
list. Nothing in §402(b) authorizes the EPA to consider the protec
tion of listed species as an end in itself when evaluating a transfer
application. And to the extent that some of §402(b)’s criteria may re
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sult in environmental benefits to marine species, Arizona has satis
fied each of those criteria. Respondents’ argument has also been dis
claimed by the FWS and the NMFS, the agencies primarily charged
with administering §7(a)(2) and the drafters of the regulations im
plementing that section. Pp. 24–25.
420 F. 3d 946, reversed and remanded.

ALITO, J., delivered the opinion of the Court, in which ROBERTS, C. J.,
and SCALIA, KENNEDY, and THOMAS, JJ., joined. STEVENS, J., filed a dis
senting opinion, in which SOUTER, GINSBURG, and BREYER, JJ., joined.
BREYER, J., filed a dissenting opinion.
 Cite as: 551 U. S. ____ (2007) 1

Opinion of the Court

NOTICE: This opinion is subject to formal revision before publication in the
preliminary print of the United States Reports. Readers are requested to
notify the Reporter of Decisions, Supreme Court of the United States, Wash
ington, D. C. 20543, of any typographical or other formal errors, in order
that corrections may be made before the preliminary print goes to press.

SUPREME COURT OF THE UNITED STATES
_________________

Nos. 06–340 and 06–549
_________________

NATIONAL ASSOCIATION OF HOME BUILDERS,
ET AL., PETITIONERS
06–340 v.
DEFENDERS OF WILDLIFE ET AL.

ENVIRONMENTAL PROTECTION AGENCY,
PETITIONER
06–549 v.
DEFENDERS OF WILDLIFE ET AL.
ON WRITS OF CERTIORARI TO THE UNITED STATES COURT OF
APPEALS FOR THE NINTH CIRCUIT
[June 25, 2007]

JUSTICE ALITO delivered the opinion of the Court.
These cases concern the interplay between two federal
environmental statutes. Section 402(b) of the Clean Water
Act requires that the Environmental Protection Agency
transfer certain permitting powers to state authorities
upon an application and a showing that nine specified
criteria have been met. Section 7(a)(2) of the Endangered
Species Act of 1973 provides that a federal agency must
consult with agencies designated by the Secretaries of
Commerce and the Interior in order to “insure that any
action authorized, funded, or carried out by such agency
. . . is not likely to jeopardize the continued existence of
any endangered species or threatened species.” The ques
tion presented is whether §7(a)(2) effectively operates as a
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Opinion of the Court

tenth criterion on which the transfer of permitting power
under the first statute must be conditioned. We conclude
that it does not. The transfer of permitting authority to
state authorities—who will exercise that authority under
continuing federal oversight to ensure compliance with
relevant mandates of the Endangered Species Act and
other federal environmental protection statutes—was
proper. We therefore reverse the judgment of the United
States Court of Appeals for the Ninth Circuit.
I
A
1
The Clean Water Act of 1972 (CWA), 86 Stat. 816, 33
U. S. C. §1251 et seq., established a National Pollution
Discharge Elimination System (NPDES) that is designed
to prevent harmful discharges into the Nation’s waters.
The Environmental Protection Agency (EPA) initially
administers the NPDES permitting system for each State,
but a State may apply for a transfer of permitting author
ity to state officials. See 33 U. S. C. §1342; see also
§1251(b) (“It is the policy of Congress that the Stat[e] . . .
implement the permit progra[m] under sectio[n] 1342 . . .
of this title”). If authority is transferred, then state offi
cials—not the federal EPA—have the primary responsibil
ity for reviewing and approving NPDES discharge per
mits, albeit with continuing EPA oversight.1
Under §402(b) of the CWA, “the Governor of each State
desiring to administer its own permit program for dis
charges into navigable waters within its jurisdiction may
submit to [the EPA] a full and complete description of the
——————
1 The State must advise the EPA of each permit it proposes to issue,

and the EPA may object to any permit. 33 U. S. C. §§1342(d)(1), (2); see
also 40 CFR §123.44(c) (2006). If the State cannot address the EPA’s
concerns, authority over the permit reverts to the EPA. 33 U. S. C.
§1342(d)(4).
 Cite as: 551 U. S. ____ (2007) 3

Opinion of the Court

program it proposes to establish and administer under
State law or under an interstate compact,” as well as a
certification “that the laws of such State . . . provide ade
quate authority to carry out the described program.” 33
U. S. C. §1342(b). The same section provides that the EPA
“shall approve each submitted program” for transfer of
permitting authority to a State “unless [it] determines
that adequate authority does not exist” to ensure that nine
specified criteria are satisfied. Ibid. These criteria all
relate to whether the state agency that will be responsible
for permitting has the requisite authority under state law
to administer the NPDES program.2 If the criteria are
met, the transfer must be approved.
2
The Endangered Species Act of 1973 (ESA), 87 Stat.
884, as amended, 16 U. S. C. §1531 et seq., is intended to
protect and conserve endangered and threatened species
and their habitats. Section 4 of the ESA directs the Secre
taries of Commerce and the Interior to list threatened and

——————
2 The State must demonstrate that it has the ability: (1) to issue
fixed-term permits that apply and ensure compliance with the CWA’s
substantive requirements and which are revocable for cause; (2) to
inspect, monitor, and enter facilities and to require reports to the
extent required by the CWA; (3) to provide for public notice and public
hearings; (4) to ensure that the EPA receives notice of each permit
application; (5) to ensure that any other State whose waters may be
affected by the issuance of a permit may submit written recommenda
tions and that written reasons be provided if such recommendations are
not accepted; (6) to ensure that no permit is issued if the Army Corps of
Engineers concludes that it would substantially impair the anchoring
and navigation of navigable waters; (7) to abate violations of permits or
the permit program, including through civil and criminal penalties; (8)
to ensure that any permit for a discharge from a publicly owned treat
ment works includes conditions requiring the identification of the type
and volume of certain pollutants; and (9) to ensure that any industrial
user of any publicly owned treatment works will comply with certain of
the CWA’s substantive provisions. §§1342(b)(1)–(9).
4 NATIONAL ASSN. OF HOME BUILDERS v. DEFENDERS

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endangered species and to designate their critical habi
tats. §1533. The Fish and Wildlife Service (FWS) admin
isters the ESA with respect to species under the jurisdic
tion of the Secretary of the Interior, while the National
Marine Fisheries Service (NMFS) administers the ESA
with respect to species under the jurisdiction of the Secre
tary of Commerce. See 50 CFR §§17.11, 222.101(a),
223.102, 402.01(b) (2006).
Section 7 of the ESA prescribes the steps that federal
agencies must take to ensure that their actions do not
jeopardize endangered wildlife and flora. Section 7(a)(2)
provides that “[e]ach Federal agency shall, in consultation
with and with the assistance of the Secretary [of Com
merce or the Interior], insure that any action authorized,
funded, or carried out by such agency (hereinafter in this
section referred to as an ‘agency action’) is not likely to
jeopardize the continued existence of any endangered
species or threatened species.” 16 U. S. C. §1536(a)(2).
Once the consultation process contemplated by §7(a)(2)
has been completed, the Secretary is required to give the
agency a written biological opinion “setting forth the
Secretary’s opinion, and a summary of the information on
which the opinion is based, detailing how the agency
action affects the species or its critical habitat.”
§1536(b)(3)(A); see also 50 CFR §402.14(h). If the Secre
tary concludes that the agency action would place the
listed species in jeopardy or adversely modify its critical
habitat, “the Secretary shall suggest those reasonable and
prudent alternatives which he believes would not violate
[§7(a)(2)] and can be taken by the Federal agency . . . in
implementing the agency action.” 16 U. S. C.
§1536(b)(3)(A); see also 50 CFR §402.14(h)(3). Regulations
promulgated jointly by the Secretaries of Commerce and
the Interior provide that, in order to qualify as a “reason
able and prudent alternative,” an alternative course of
action must be able to be implemented in a way “consis
 Cite as: 551 U. S. ____ (2007) 5

Opinion of the Court

tent with the scope of the Federal agency’s legal authority
and jurisdiction.” §402.02. Following the issuance of a
“jeopardy” opinion, the agency must either terminate the
action, implement the proposed alternative, or seek an
exemption from the Cabinet-level Endangered Species
Committee pursuant to 16 U. S. C. §1536(e). The regula
tions also provide that “Section 7 and the requirements of
this part apply to all actions in which there is discretion
ary Federal involvement or control.” 50 CFR §402.03.
B
1
In February 2002, Arizona officials applied for EPA
authorization to administer that State’s NPDES program.3
The EPA initiated consultation with the FWS to deter
mine whether the transfer of permitting authority would
adversely affect any listed species.
The FWS regional office concluded that the transfer of
authority would not cause any direct impact on water
quality that would adversely affect listed species. App. to
Pet. for Cert. in No. 06–340, p. 564. However, the FWS
office was concerned that the transfer could result in the
issuance of more discharge permits, which would lead to
more development, which in turn could have an indirect
adverse effect on the habitat of certain upland species,
such as the cactus ferruginous pygmy-owl and the Pima
pineapple cactus. Specifically, the FWS feared that, be
cause §7(a)(2)’s consultation requirement does not apply to
permitting decisions by state authorities,4 the transfer of
authority would empower Arizona officials to issue indi
vidual permits without considering and mitigating their
——————
3 At the time when Arizona applied, the EPA had already transferred

permitting authority to local authorities in 44 other States and several
United States Territories.
4 By its terms, §7(a)(2)’s consultation requirement applies only to

“action[s] authorized, funded, or carried out” by “Federal agenc[ies].”
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indirect impact on these upland species. Id., at 565–566.
The FWS regional office therefore urged that, in consider
ing the proposed transfer of permitting authority, those
involved in the consultation process should take these
potential indirect impacts into account.
The EPA disagreed, maintaining that “its approval
action, which is an administrative transfer of authority,
[would not be] the cause of future non-discharge-related
impacts on endangered species from projects requiring
State NPDES permits.” Id., at 564. As a factual matter,
the EPA believed that the link between the transfer of
permitting authority and the potential harm that could
result from increased development was too attenuated.
Id., at 654. And as a legal matter, the EPA concluded that
the mandatory nature of CWA §402(b)—which directs that
the EPA “shall approve” a transfer request if that section’s
nine statutory criteria are met—stripped it of authority to
disapprove a transfer based on any other considerations.
Id., at 654–655.
Pursuant to procedures set forth in a memorandum of
understanding between the agencies, the dispute was
referred to the agencies’ national offices for resolution. In
December 2002, the FWS issued its biological opinion,
which concluded that the requested transfer would not
cause jeopardy to listed species. The opinion reasoned
that “the loss of section 7-related conservation benefits . . .
is not an indirect effect of the authorization action,” id., at
117, because
“loss of any conservation benefit is not caused by
EPA’s decision to approve the State of Arizona’s pro
gram. Rather, the absence of the section 7 process
that exists with respect to Federal NPDES permits re
flects Congress’ decision to grant States the right to
administer these programs under state law provided
the State’s program meets the requirements of
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[§]402(b) of the Clean Water Act.” Id., at 114.
In addition, the FWS opined that the EPA’s continuing
oversight of Arizona’s permitting program, along with
other statutory protections, would adequately protect
listed species and their habitats following the transfer.
Id., at 101–107.
The EPA concluded that Arizona had met each of the
nine statutory criteria listed in §402(b) and approved the
transfer of permitting authority. In the notice announcing
the approval of the transfer, the EPA noted that the issu
ance of the FWS’s biological opinion had “conclude[d] the
consultation process required by ESA section 7(a)(2) and
reflects the [FWS’] agreement with EPA that the approval
of the State program meets the substantive requirements
of the ESA.” Id., at 73.
2
On April 2, 2003, respondents filed a petition in the
United States Court of Appeals for the Ninth Circuit
seeking review of the transfer pursuant to 33 U. S. C.
§1369(b)(1)(D), which allows private parties to seek direct
review of the EPA’s determinations regarding state per
mitting programs in the federal courts of appeals. The
court granted petitioner National Association of Home-
builders leave to intervene as a respondent in that case.
Respondent Defenders of Wildlife also filed a separate
action in the United States District Court for the District
of Arizona, alleging, among other things, that the biologi
cal opinion issued by the FWS in support of the proposed
transfer did not comply with the ESA’s standards. The
District Court severed that claim and transferred it to the
Court of Appeals for the Ninth Circuit, which consolidated
the case with the suit challenging the EPA transfer. See
420 F. 3d 946 (2005).
A divided panel of the Ninth Circuit held that the EPA’s
approval of the transfer was arbitrary and capricious
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because the EPA “relied during the administrative pro
ceedings on legally contradictory positions regarding its
section 7 obligations.” Id., at 959. The court concluded
that the EPA “fail[ed] to understand its own authority
under section 7(a)(2) to act on behalf of listed species and
their habitat,” id., at 977, because “the two propositions
that underlie the EPA’s action—that (1) it must, under the
[ESA], consult concerning transfers of CWA permitting
authority, but (2) it is not permitted, as a matter of law, to
take into account the impact on listed species in making
the transfer decision—cannot both be true,” id., at 961.
The court therefore concluded that it was required to
“remand to the agency for a plausible explanation of its
decision, based on a single, coherent interpretation of the
statute.” Id., at 962.
The panel majority, however, did not follow this course
of action. Rather, the panel went on to review the EPA’s
substantive construction of the statutes at issue and held
that the ESA granted the EPA both the power and the
duty to determine whether its transfer decision would
jeopardize threatened or endangered species. The panel
did not dispute that Arizona had met the nine criteria set
forth in §402(b) of the CWA, but the panel nevertheless
concluded that §7(a)(2) of the ESA provided an “affirma
tive grant of authority to attend to [the] protection of
listed species,” id., at 965, in effect adding a tenth crite
rion to those specified in §402(b). The panel dismissed the
argument that the EPA’s approval of the transfer applica
tion was not subject to §7(a)(2) because it was not a “dis
cretionary action” within the meaning of 50 CFR §402.03
(interpreting §7(a)(2) to apply only to agency actions “in
which there is discretionary Federal involvement and
control”). 420 F. 3d, at 967–969. It viewed the FWS’s
regulation as merely “coterminous” with the express
statutory language encompassing all agency actions that
are “ ‘authorized, funded, or carried out’ ” by the agency.
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Opinion of the Court

Id., at 969 (quoting 16 U. S. C. §1536(a)(2)). On these
grounds, the court granted the petition and vacated the
EPA’s transfer decision.
In dissent, Judge Thompson explained that the transfer
decision was not a “discretionary action” under 50 CFR
§402.03 because “[t]he Clean Water Act, by its very terms,
permits the EPA to consider only the nine specified fac
tors. If a state’s proposed permitting program meets the
enumerated requirements,” he reasoned, “the EPA admin
istrator ‘shall approve’ the program. 33 U. S. C. §1342(b).
This [c]ongressional directive does not permit the EPA to
impose additional conditions.” 420 F. 3d, at 980.
The Ninth Circuit denied rehearing and rehearing en
banc. 450 F. 3d 394 (2006). Writing for the six judges who
dissented from the denial of rehearing en banc, Judge
Kozinski disagreed with the panel’s conclusion that the
EPA’s analysis was so internally inconsistent as to be
arbitrary and capricious. He further noted that, if the
panel was correct on this point, the proper resolution
would have been to remand to the EPA for further expla
nation. Id., at 396–398. On the statutory question, Judge
Kozinski echoed Judge Thompson’s conclusion that once
the nine criteria set forth in §402(b) of the CWA are satis
fied, a transfer is mandatory and nondiscretionary. Id., at
397–399. He rejected the panel majority’s broad construc
tion of ESA §7(a)(2), concluding that “[i]f the ESA were as
powerful as the majority contends, it would modify not
only the EPA’s obligation under the CWA, but every cate
gorical mandate applicable to every federal agency.” Id., at
399, n. 4.
The Ninth Circuit’s construction of §7(a)(2) is at odds
with that of other Courts of Appeals. Compare 420 F. 3d
946 (case below), with Platte River Whooping Crane Criti
cal Habitat Maintenance Trust v. FERC, 962 F. 2d 27, 33–
34 (CADC 1992), and American Forest & Paper Associa
tion v. EPA, 137 F. 3d 291, 298–299 (CA5 1998). We
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granted certiorari to resolve this conflict, 549 U. S. ___
(2007), and we now reverse.
II
Before addressing this question of statutory interpreta
tion, however, we first consider whether the Court of
Appeals erred in holding that the EPA’s transfer decision
was arbitrary and capricious because, in that court’s
words, the agencies involved in the decision “relied . . . on
legally contradictory positions regarding [their] section 7
obligations.” App. to Pet. for Cert. in No. 06–340, at 23.
As an initial matter, we note that if the EPA’s action
was arbitrary and capricious, as the Ninth Circuit held,
the proper course would have been to remand to the
agency for clarification of its reasons. See Gonzales v.
Thomas, 547 U. S. 183 (2006) (per curiam). Indeed, the
court below expressly recognized that this finding required
it to “remand to the agency for a plausible explanation of
its decision, based on a single, coherent interpretation of
the statute.” App. to Pet. for Cert. in No. 06–340, at 28.
But the Ninth Circuit did not take this course; instead, it
jumped ahead to resolve the merits of the dispute. In so
doing, it erroneously deprived the agency of its usual
administrative avenue for explaining and reconciling the
arguably contradictory rationales that sometimes appear
in the course of lengthy and complex administrative deci
sions. We need not examine this question further, how
ever, because we conclude that the Ninth Circuit’s deter
mination that the EPA’s action was arbitrary and
capricious is not fairly supported by the record.
Review under the arbitrary and capricious standard is
deferential; we will not vacate an agency’s decision unless
it
“has relied on factors which Congress had not in
tended it to consider, entirely failed to consider an
important aspect of the problem, offered an explana
 Cite as: 551 U. S. ____ (2007) 11

Opinion of the Court

tion for its decision that runs counter to the evidence
before the agency, or is so implausible that it could
not be ascribed to a difference in view or the product
of agency expertise.” Motor Vehicle Mfrs. Assn. of
United States, Inc. v. State Farm Mut. Automobile Ins.
Co., 463 U. S. 29, 43 (1983).
“We will, however, ‘uphold a decision of less than ideal
clarity if the agency’s path may reasonably be discerned.’ ”
Ibid. (quoting Bowman Transp., Inc. v. Arkansas-Best
Freight System, Inc., 419 U. S. 281, 286 (1974)).
The Court of Appeals concluded that the EPA’s decision
was “internally inconsistent” because, in its view, the
agency stated—both during preliminary review of Ari
zona’s transfer application and in the Federal Register
notice memorializing its final action—“that section 7
requires consultation regarding the effect of a permitting
transfer on listed species.” App. to Pet. for Cert. in No.
06–340, at 23.
With regard to the various statements made by the
involved agencies’ regional offices during the early stages
of consideration, the only “inconsistency” respondents can
point to is the fact that the agencies changed their
minds—something that, as long as the proper procedures
were followed, they were fully entitled to do. The federal
courts ordinarily are empowered to review only an
agency’s final action, see 5 U. S. C. §704, and the fact that
a preliminary determination by a local agency representa
tive is later overruled at a higher level within the agency
does not render the decisionmaking process arbitrary and
capricious.
Respondents also point to the final Federal Register
notice memorializing the EPA’s approval of Arizona’s
transfer application. This notice stated that the FWS’s
issuance of its biological opinion had “conclude[d] the
consultation process required by ESA section 7(a)(2).”
12 NATIONAL ASSN. OF HOME BUILDERS v. DEFENDERS
OF WILDLIFE
Opinion of the Court

App. to Pet. for Cert. in No. 06–340, at 73. Respondents
contend that this statement is inconsistent with the EPA’s
previously expressed position—and their position
throughout this litigation—that §7(a)(2)’s consultation
requirement is not triggered by a transfer application
under §402 of the CWA.
We are not persuaded that this statement constitutes
the type of error that requires a remand. By the time the
Federal Register statement was issued, the EPA had
already consulted with the FWS about the Arizona appli
cation, and the question whether that consultation had
been required, as opposed to voluntarily undertaken by
the agency, was simply not germane to the final agency
transfer decision. The Federal Register statement, in
short, was dictum, and it had no bearing on the final
agency action that respondents challenge. Mindful of
Congress’ admonition that in reviewing agency action,
“due account shall be taken of the rule of prejudicial er
ror,” 5 U. S. C. §706, we do not believe that this stray
statement, which could have had no effect on the underly
ing agency action being challenged, requires that we
further delay the transfer of permitting authority to Ari
zona by remanding to the agency for clarification. See also
PDK Labs., Inc. v. United States Drug Enforcement
Admin., 362 F. 3d 786, 799 (CADC 2004) (“In administra
tive law, as in federal civil and criminal litigation, there is
a harmless error rule”).5
——————
5 We also note that the agencies involved have resolved any ambigu

ity in their positions going forward. Following the issuance of the
panel’s opinion below, the EPA—in connection with the State of
Alaska’s pending application for transfer of NPDES permitting author
ity—requested confirmation from the FWS and NMFS of the EPA’s
position that “the no-jeopardy and consultation duties of ESA Section
7(a)(2) do not apply to approval of a State’s application to administer
the NPDES program,” in the apparent hope that obtaining those
agencies’ views “in advance of processing Alaska’s application may
avoid a repetition of” the confusion that occurred during the Arizona
 Cite as: 551 U. S. ____ (2007) 13

Opinion of the Court

We further disagree with respondents’ suggestion that,
by allegedly altering its legal position while the Arizona
transfer decision and its associated litigation was pending,
the “EPA is effectively nullifying respondents’ rights to
participate in administrative proceedings concerning
Arizona’s application, and particularly respondents’ rights
under EPA’s own regulations to comment on NPDES
transfer applications.” Brief for Respondents 28 (citing 40
CFR §123.61(b); emphasis deleted). Consistent with EPA
regulations, the agency made available “a comment period
of not less than 45 days during which interested members
of the public [could] express their views on the State pro
gram.” §123.61(a)(1). Respondents do not suggest that
they were deprived of their right to comment during this
period.6
Respondents also contend that if the case were re
manded to the EPA, they would raise additional chal
lenges—including, for example, a challenge to the EPA’s
provision of financial assistance to Arizona for the admini
stration of its NPDES program. However, as explained
below, any such agency action is separate and independ
ent of the agency’s decision to authorize the transfer of
——————
permitting process. App. to Pet. for Cert. in No. 06–549, at 96a, 95a. In
response, both the FWS and the NMFS confirmed their understanding
that “there is no need to conduct Section 7 consultations on proposed
actions to approve State NPDES programs because such actions are not
the cause of any impact on listed species and do not constitute discre
tionary federal agency actions to which Section 7 applies.” Id., at 107a;
see also id., at 116a (NMFS “concur[s] with EPA’s conclusion that EPA
is not required to engage in section 7 consultation on applications to
approve State programs in situations under Section 402(b) of the
CWA”).
6 Nor is there any independent right to public comment with regard to

consultations conducted under §7(a)(2)—a consultation process that we
conclude, in any case, was not required here. See 51 Fed. Reg. 19928
(1986) (“Nothing in section 7 authorizes or requires the Service to
provide for public involvement (other than that of the applicant) in the
‘interagency’ consultation process”).
14 NATIONAL ASSN. OF HOME BUILDERS v. DEFENDERS
OF WILDLIFE
Opinion of the Court

permitting authority pursuant to §402(b). See n. 11, infra.
We express no opinion as to the viability of a separate
administrative or legal challenge to such actions.
III

A

We turn now to the substantive statutory question
raised by the petitions, a question that requires us to
mediate a clash of seemingly categorical—and, at first
glance, irreconcilable—legislative commands. Section
402(b) of the CWA provides, without qualification, that the
EPA “shall approve” a transfer application unless it de
termines that the State lacks adequate authority to per
form the nine functions specified in the section. 33
U. S. C. §1342(b). By its terms, the statutory language is
mandatory and the list exclusive; if the nine specified
criteria are satisfied, the EPA does not have the discretion
to deny a transfer application. Cf. Lopez v. Davis, 531
U. S. 230, 241 (2001) (noting Congress’ “use of a manda
tory ‘shall’ . . . to impose discretionless obligations”); Lexe
con Inc. v. Milberg Weiss Bershad Hynes & Lerach, 523
U. S. 26, 35 (1998) (“[T]he mandatory ‘shall’ . . . normally
creates an obligation impervious to judicial discretion”);
Association of Civil Technicians v. FLRA, 22 F. 3d 1150,
1153 (CADC 1994) (“The word ‘shall’ generally indicates a
command that admits of no discretion on the part of the
person instructed to carry out the directive”); Black’s Law
Dictionary 1375 (6th ed. 1990) (“As used in statutes . . .
this word is generally imperative or mandatory”). Neither
respondents nor the Ninth Circuit has ever disputed that
Arizona satisfied each of these nine criteria. See 420
F. 3d, at 963, n. 11; Brief for Respondents 19, n. 8.
The language of §7(a)(2) of the ESA is similarly impera
tive: it provides that “[e]ach Federal agency shall, in con
sultation with and with the assistance of the Secretary,
insure that any action authorized, funded, or carried out
 Cite as: 551 U. S. ____ (2007) 15

Opinion of the Court

by such agency . . . is not likely to jeopardize” endangered
or threatened species or their habitats. 16 U. S. C.
§1536(a)(2). This mandate is to be carried out through
consultation and may require the agency to adopt an
alternative course of action. As the author of the panel
opinion below recognized, applying this language literally
would “ad[d] one [additional] requirement to the list of
considerations under the Clean Water Act permitting
transfer provision.” 450 F. 3d, at 404, n. 2 (Berzon, J.,
concurring in denial of rehearing en banc) (emphasis in
original). That is, it would effectively repeal the manda
tory and exclusive list of criteria set forth in §402(b), and
replace it with a new, expanded list that includes §7(a)(2)’s
no-jeopardy requirement.
B
While a later enacted statute (such as the ESA) can
sometimes operate to amend or even repeal an earlier
statutory provision (such as the CWA), “repeals by impli
cation are not favored” and will not be presumed unless
the “intention of the legislature to repeal [is] clear and
manifest.” Watt v. Alaska, 451 U. S. 259, 267 (1981) (in
ternal quotation marks omitted). We will not infer a
statutory repeal “unless the later statute ‘ “expressly
contradict[s] the original act” ’ or unless such a construc
tion ‘ “is absolutely necessary . . . in order that [the] words
[of the later statute] shall have any meaning at all.” ’ ”
Traynor v. Turnage, 485 U. S. 535, 548 (1988) (quoting
Radzanower v. Touche Ross & Co., 426 U. S. 148, 153
(1976), in turn quoting T. Sedgwick, The Interpretation
and Construction of Statutory and Constitutional Law 98
(2d ed. 1874)); see also Branch v. Smith, 538 U. S. 254,
273 (2003) (“An implied repeal will only be found where
provisions in two statutes are in ‘irreconcilable conflict,’ or
where the latter Act covers the whole subject of the earlier
one and ‘is clearly intended as a substitute’ ”); Posadas v.
16 NATIONAL ASSN. OF HOME BUILDERS v. DEFENDERS
OF WILDLIFE
Opinion of the Court

National City Bank, 296 U. S. 497, 503 (1936) (“[T]he
intention of the legislature to repeal must be clear and
manifest”). Outside these limited circumstances, “a stat
ute dealing with a narrow, precise, and specific subject is
not submerged by a later enacted statute covering a more
generalized spectrum.” Radzanower, supra, at 153.
Here, reading §7(a)(2) as the Court of Appeals did would
effectively repeal §402(b)’s statutory mandate by engraft
ing a tenth criterion onto the CWA.7 Section 402(b) of the
CWA commands that the EPA “shall” issue a permit
whenever all nine exclusive statutory prerequisites are
met. Thus, §402(b) does not just set forth minimum re
quirements for the transfer of permitting authority; it
affirmatively mandates that the transfer “shall” be ap
proved if the specified criteria are met. The provision
operates as a ceiling as well as a floor. By adding an
additional criterion, the Ninth Circuit’s construction of
§7(a)(2) raises that floor and alters §402(b)’s statutory
command.8
——————
7 JUSTICE STEVENS’ dissenting opinion attempts to paper over this

conflict by suggesting that the EPA and the agencies designated by the
Secretary of the Interior could reconcile the commands of the CWA and
the ESA by “generat[ing] an alternative course of action whereby the
transfer could still take place . . . but in such a way that would honor
the mandatory requirements of §7(a)(2).” Post, at 15. For example, it
suggests that the EPA could condition transfers of permitting authority
on the State’s acceptance of additional continuing oversight by the EPA
(presumably beyond that oversight already contemplated by the CWA’s
statutory language). Post, at 17–19. But such a take-it-or-leave-it
approach, no less than a straightforward rejection of a transfer applica
tion, would impose conditions on an NPDES transfer beyond those set
forth in §402(b), and thus alter the CWA’s statutory command.
8 It does not matter whether this alteration is characterized as an

amendment or a partial repeal. Every amendment of a statute effects a
partial repeal to the extent that the new statutory command displaces
earlier, inconsistent commands, and we have repeatedly recognized
that implied amendments are no more favored than implied repeals.
See, e.g., Regional Rail Reorganization Act Cases, 419 U. S. 102, 134
 Cite as: 551 U. S. ____ (2007) 17

Opinion of the Court

The Ninth Circuit’s reading of §7(a)(2) would not only
abrogate §402(b)’s statutory mandate, but also result in
the implicit repeal of many additional otherwise categori
cal statutory commands. Section 7(a)(2) by its terms
applies to “any action authorized, funded, or carried out
by” a federal agency—covering, in effect, almost anything
that an agency might do. Reading the provision broadly
would thus partially override every federal statute man
dating agency action by subjecting such action to the
further condition that it pose no jeopardy to endangered
species. See, e.g., Platte River Whooping Crane Critical
Habitat Maintenance Trust v. FERC, 962 F. 2d, at 33–34
(considering whether §7(a)(2) overrides the Federal Power
Act’s prohibition on amending annual power licenses).
While the language of §7(a)(2) does not explicitly repeal
any provision of the CWA (or any other statute), reading it
for all that it might be worth runs foursquare into our
presumption against implied repeals.
C
1
The agencies charged with implementing the ESA have
attempted to resolve this tension through regulations
implementing §7(a)(2). The NMFS and FWS, acting
jointly on behalf of the Secretaries of Commerce and the
Interior and following notice-and-comment rulemaking
procedures, have promulgated a regulation stating that
“Section 7 and the requirements of this part apply to all
——————
(1974) (“ ‘A new statute will not be read as wholly or even partially
amending a prior one unless there exists a ‘positive repugnancy’ be
tween the provisions of the new and those of the old that cannot be
reconciled’ ”) (quoting In re Penn Central Transportation Co., 384
F. Supp. 895, 943 (Sp. Ct. R. R. R. A. 1974)); United States v. Welden,
377 U. S. 95, 103, n. 12 (1964) (“Amendments by implication . . . are not
favored”); United States v. Madigan, 300 U. S. 500, 506 (1937) (“[T]he
modification by implication of the settled construction of an earlier and
different section is not favored”).
18 NATIONAL ASSN. OF HOME BUILDERS v. DEFENDERS
OF WILDLIFE
Opinion of the Court

actions in which there is discretionary Federal involve
ment or control.” 50 CFR §402.03 (emphasis added).
Pursuant to this regulation, §7(a)(2) would not be read as
impliedly repealing nondiscretionary statutory mandates,
even when they might result in some agency action.
Rather, the ESA’s requirements would come into play only
when an action results from the exercise of agency discre
tion. This interpretation harmonizes the statutes by
giving effect to the ESA’s no-jeopardy mandate whenever
an agency has discretion to do so, but not when the agency
is forbidden from considering such extrastatutory factors.
We have recognized that “[t]he latitude the ESA gives
the Secretary in enforcing the statute, together with the
degree of regulatory expertise necessary to its enforce
ment, establishes that we owe some degree of deference to
the Secretary’s reasonable interpretation” of the statutory
scheme. Babbitt v. Sweet Home Chapter, Communities for
Great Ore., 515 U. S. 687, 703 (1995). But such deference
is appropriate only where “Congress has not directly ad
dressed the precise question at issue” through the statu
tory text. Chevron U. S. A. Inc. v. Natural Resources
Defense Council, Inc., 467 U. S. 837, 843 (1984).
“If the intent of Congress is clear, that is the end of
the matter; for the court, as well as the agency, must
give effect to the unambiguously expressed intent of
Congress. . . . [However,] if the statute is silent or am
biguous with respect to the specific issue, the question
for the court is whether the agency’s answer is based
on a permissible construction of the statute.” Id., at
842–843 (footnotes omitted).
In making the threshold determination under Chevron,
“a reviewing court should not confine itself to examining a
particular statutory provision in isolation.” FDA v. Brown
& Williamson Tobacco Corp., 529 U. S. 120, 132 (2000).
Rather, “[t]he meaning—or ambiguity—of certain words or
 Cite as: 551 U. S. ____ (2007) 19

Opinion of the Court

phrases may only become evident when placed in con
text. . . . It is a ‘fundamental canon of statutory construc
tion that the words of a statute must be read in their
context and with a view to their place in the overall statu
tory scheme.’ ” Id., at 132–133 (quoting Davis v. Michigan
Dept. of Treasury, 489 U. S. 803, 809 (1989)).
We must therefore read §7(a)(2) of the ESA against the
statutory backdrop of the many mandatory agency direc
tives whose operation it would implicitly abrogate or
repeal if it were construed as broadly as the Ninth Circuit
did below. When §7(a)(2) is read this way, we are left with
a fundamental ambiguity that is not resolved by the statu
tory text. An agency cannot simultaneously obey the
differing mandates set forth in §7(a)(2) of the ESA and
§402(b) of the CWA, and consequently the statutory lan
guage—read in light of the canon against implied re
peals—does not itself provide clear guidance as to which
command must give way.
In this situation, it is appropriate to look to the imple
menting agency’s expert interpretation, which cabins
§7(a)(2)’s application to “actions in which there is discre
tionary Federal involvement or control.” 50 CFR §402.03.
This reading harmonizes the statutes by applying §7(a)(2)
to guide agencies’ existing discretionary authority, but not
reading it to override express statutory mandates.
2
We conclude that this interpretation is reasonable in
light of the statute’s text and the overall statutory scheme,
and that it is therefore entitled to deference under Chev
ron. Section 7(a)(2) requires that an agency “insure” that
the actions it authorizes, funds, or carries out are not
likely to jeopardize listed species or their habitats. To
“insure” something—as the court below recognized—
means “ ‘[t]o make certain, to secure, to guarantee (some
thing, event, etc.).’ ” 420 F. 3d, at 963 (quoting 7 Oxford
20 NATIONAL ASSN. OF HOME BUILDERS v. DEFENDERS
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Opinion of the Court

English Dictionary 1059 (2d ed. 1989)). The regulation’s
focus on “discretionary” actions accords with the common
sense conclusion that, when an agency is required to do
something by statute, it simply lacks the power to “insure”
that such action will not jeopardize endangered species.
This reasoning is supported by our decision in Depart
ment of Transportation v. Public Citizen, 541 U. S. 752
(2004). That case concerned safety regulations that were
promulgated by the Federal Motor Carrier Safety Admini
stration (FMCSA) and had the effect of triggering a Presi
dential directive allowing Mexican trucks to ply their
trade on United States roads. The Court held that the
National Environmental Policy Act (NEPA) did not re
quire the agency to assess the environmental effects of
allowing the trucks entry because “the legally relevant
cause of the entry of the Mexican trucks is not FMCSA’s
action, but instead the actions of the President in lifting
the moratorium and those of Congress in granting the
President this authority while simultaneously limiting
FMCSA’s discretion.” Id., at 769 (emphasis in original).
The Court concluded that “where an agency has no ability
to prevent a certain effect due to its limited statutory
authority over the relevant actions, the agency cannot be
considered a legally relevant ‘cause’ of the effect.” Id., at
770.
We do not suggest that Public Citizen controls the out
come here; §7(a)(2), unlike NEPA, imposes a substantive
(and not just a procedural) statutory requirement, and
these cases involve agency action more directly related to
environmental concerns than the FMCSA’s truck safety
regulations. But the basic principle announced in Public
Citizen—that an agency cannot be considered the legal
“cause” of an action that it has no statutory discretion not
to take—supports the reasonableness of the FWS’s inter
pretation of §7(a)(2) as reaching only discretionary agency
actions. See also California v. United States, 438 U. S.
 Cite as: 551 U. S. ____ (2007) 21

Opinion of the Court

645, 668, n. 21 (1978) (holding that a statutory require
ment that federal operating agencies conform to state
water usage rules applied only to the extent that it was
not “inconsistent with other congressional directives”).
3
The court below simply disregarded §402.03’s interpre
tation of the ESA’s reach, dismissing “the regulation’s
reference to ‘discretionary . . . involvement’ ” as merely
“congruent with the statutory reference to actions ‘author
ized, funded, or carried out’ by the agency.” 420 F. 3d,
968. But this reading cannot be right. Agency discretion
presumes that an agency can exercise “judgment” in con
nection with a particular action. See Citizens to Preserve
Overton Park, Inc. v. Volpe, 401 U. S. 402, 415–416 (1971);
see also Random House Dictionary of the English Lan
guage 411 (unabridged ed. 1967) (“discretion” defined as
“the power or right to decide or act according to one’s own
judgment; freedom of judgment or choice”). As the manda
tory language of §402(b) itself illustrates, not every action
authorized, funded, or carried out by a federal agency is a
product of that agency’s exercise of discretion.
The dissent’s interpretation of §402.03 is similarly
implausible. The dissent would read the regulation as
simply clarifying that discretionary agency actions are
included within the scope of §7(a)(2), but not confining the
statute’s reach to such actions. See post, at 7–11. But this
reading would render the regulation entirely superfluous.
Nothing in either §7(a)(2) or the other agency regulations
interpreting that section, see §402.02, suggests that dis
cretionary actions are excluded from the scope of the ESA,
and there is thus no need for a separate regulation to
bring them within the statute’s scope. On the dissent’s
reading, §402.03’s reference to “discretionary” federal
involvement is mere surplusage, and we have cautioned
against reading a text in a way that makes part of it re
22 NATIONAL ASSN. OF HOME BUILDERS v. DEFENDERS
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Opinion of the Court

dundant. See, e.g., TRW Inc. v. Andrews, 534 U. S. 19, 31
(2001).
This history of the regulation also supports the reading
to which we defer today. As the dissent itself points out,
the proposed version of §402.03 initially stated that “Sec
tion 7 and the requirements of this Part apply to all ac
tions in which there is Federal involvement or control,” 48
Fed. Reg. 29999 (1983) (emphasis added); the Secretary of
the Interior modified this language to provide (as adopted
in the Final Rule now at issue) that the statuory require
ments apply to “all actions in which there is discretionary
Federal involvement or control,” 51 Fed. Reg. 19958 (1986)
(emphasis added). The dissent’s reading would rob the
word “discretionary” of any effect, and substitute the
earlier, proposed version of the regulation for the text that
was actually adopted.
In short, we read §402.03 to mean what it says: that
§7(a)(2)’s no-jeopardy duty covers only discretionary
agency actions and does not attach to actions (like the
NPDES permitting transfer authorization) that an agency
is required by statute to undertake once certain specified
triggering events have occurred. This reading not only is
reasonable, inasmuch as it gives effect to the ESA’s provi
sion, but also comports with the canon against implied
repeals because it stays §7(a)(2)’s mandate where it would
effectively override otherwise mandatory statutory duties.
D
Respondents argue that our opinion in TVA v. Hill, 437
U. S. 153 (1978), supports their contrary position. In that
case, we held that the ESA prohibited the Tennessee
Valley Authority (TVA) from putting into operation the
Tellico Dam—despite the fact that the agency had already
spent over $100 million on the nearly completed project—
because doing so would have threatened the critical habi
tat of the endangered snail darter. In language on which
 Cite as: 551 U. S. ____ (2007) 23

Opinion of the Court

respondents rely, the Court concluded that “the ordinary
meaning” of §7 of the ESA contained “no exemptions” and
reflected “a conscious decision by Congress to give endan
gered species priority over the ‘primary missions’ of fed
eral agencies.” Id., at 173, 185, 188.
TVA v. Hill, however, had no occasion to answer the
question presented in these cases. That case was decided
almost a decade before the adoption in 1986 of the regula
tions contained in 50 CFR §402.03. And in any event, the
construction project at issue in TVA v. Hill, while expen
sive, was also discretionary. The TVA argued that by
continuing to make lump-sum appropriations to the TVA,
some of which were informally earmarked for the Tellico
Dam project, Congress had implicitly repealed §7’s no-
jeopardy requirement as it applied to that project. See 437
U. S., at 189–193. The Court rejected this argument,
concluding that “[t]he Appropriations Acts did not them
selves identify the projects for which the sums had been
appropriated” and that reports by congressional commit
tees allegedly directing the TVA to complete the project
lacked the force of law. Id., at 189, n. 35. Central to the
Court’s decision was the conclusion that Congress did not
mandate that the TVA put the dam into operation; there
was no statutory command to that effect; and there was
therefore no basis for contending that applying the ESA’s
no-jeopardy requirement would implicitly repeal another
affirmative congressional directive.9

——————
9 The dissent is incorrect in suggesting that “if the Secretary of the

Interior had not declared the snail darter an endangered species . . . the
TVA surely would have been obligated to spend the additional funds
that Congress appropriated to complete the project.” Post, at 4. To the
contrary, the Court in TVA v. Hill found that there was no clear repug
nancy between the ESA and the Acts appropriating funds to the TVA
because the latter simply did not require the agency to use any of the
generally appropriated funds to complete the Tellico Dam project. 437
U. S., at 189–193.
24 NATIONAL ASSN. OF HOME BUILDERS v. DEFENDERS
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Opinion of the Court

TVA v. Hill thus supports the position, expressed in
§402.03, that the ESA’s no-jeopardy mandate applies to
every discretionary agency action—regardless of the ex
pense or burden its application might impose. But that
case did not speak to the question whether §7(a)(2) applies
to non-discretionary actions, like the one at issue here.
The regulation set forth in 50 CFR §402.03 addressed that
question, and we defer to its reasonable interpretation.
IV
Finally, respondents and their amici argue that, even if
§7(a)(2) is read to apply only to “discretionary” agency
actions, the decision to transfer NPDES permitting au
thority to Arizona represented such an exercise of discre
tion. They contend that the EPA’s decision to authorize a
transfer is not entirely mechanical; that it involves some
exercise of judgment as to whether a State has met the
criteria set forth in §402(b); and that these criteria incor
porate references to wildlife conservation that bring con
sideration of §7(a)(2)’s no-jeopardy mandate properly
within the agency’s discretion.
The argument is unavailing. While the EPA may exer
cise some judgment in determining whether a State has
demonstrated that it has the authority to carry out
§402(b)’s enumerated statutory criteria, the statute clearly
does not grant it the discretion to add another entirely
separate prerequisite to that list. Nothing in the text of
§402(b) authorizes the EPA to consider the protection of
threatened or endangered species as an end in itself when
evaluating a transfer application. And to the extent that
some of the §402(b) criteria may result in environmental
benefits to marine species,10 there is no dispute that Ari
——————
10 Forexample, §402(b) requires the EPA to consider whether the
State has the legal authority to enforce applicable water quality stan
dards—some of which, in turn, are informed by the “judgment” of the
EPA’s Administrator. 33 U. S. C. §1342(b)(1)(A); see also, e.g., §1312.
 Cite as: 551 U. S. ____ (2007) 25

Opinion of the Court

zona has satisfied each of those statutory criteria.
Respondents’ argument has been disclaimed not only by
the EPA, but also by the FWS and the NMFS, the two
agencies primarily charged with administering §7(a)(2)
and the drafters of the regulations implementing that
section. Each agency recently issued a formal letter con
cluding that the authorization of an NPDES permitting
transfer is not the kind of discretionary agency action that
is covered by §402.03. See App. to Pet. for Cert. in No. 06–
549, at 103a–116a. An agency’s interpretation of the
meaning of its own regulations is entitled to deference
“unless plainly erroneous or inconsistent with the regula
tion,” Auer v. Robbins, 519 U. S. 452, 461 (1997) (internal
quotation marks omitted), and that deferential standard is
plainly met here.11

——————
But the permit transfer process does not itself require scrutiny of the
underlying standards or of their effect on marine or wildlife—only of
the state applicant’s “authority . . . [t]o issue permits which . . . apply,
and insure compliance with” the applicable standards. §1342(b)(1)(A)
(emphasis added). In any event, respondents do not dispute that, as
both the EPA and the FWS determined, the transfer of permitting
authority to Arizona officials would have no adverse water quality
related impact on any listed species. See App. to Pet. for Cert. in No.
06–340, at 562–563, 615–617.
11 Respondents also contend that the EPA has taken, or will take,

other discretionary actions apart from the transfer authorization that
implicate the ESA. For example, they argue that the EPA’s alleged
provision of funding to Arizona for the administration of its clean water
programs is the kind of discretionary agency action that is subject to
§7(a)(2). However, assuming this is true, any such funding decision is a
separate agency action that is outside the scope of this lawsuit. Re
spondents also point to the fact that, following the transfer of permit
ting authority, the EPA will retain oversight authority over the state
permitting process, including the power to object to proposed permits.
But the fact that the EPA may exercise discretionary oversight author
ity—which may trigger §7(a)(2)’s consultation and no-jeopardy obliga
tions—after the transfer does not mean that the decision authorizing
the transfer is itself discretionary.
26 NATIONAL ASSN. OF HOME BUILDERS v. DEFENDERS
OF WILDLIFE
Opinion of the Court

* * *
Applying Chevron, we defer to the agency’s reasonable
interpretation of ESA §7(a)(2) as applying only to “actions
in which there is discretionary Federal involvement or
control.” 50 CFR §402.03. Since the transfer of NPDES
permitting authority is not discretionary, but rather is
mandated once a State has met the criteria set forth in
§402(b) of the CWA, it follows that a transfer of NPDES
permitting authority does not trigger §7(a)(2)’s consulta
tion and no-jeopardy requirements. Accordingly, the
judgment of the Court of Appeals for the Ninth Circuit is
reversed, and these cases are remanded for further pro
ceedings consistent with this opinion.
 Cite as: 551 U. S. ____ (2007) 1

STEVENS, J., dissenting

SUPREME COURT OF THE UNITED STATES
_________________

Nos. 06–340 and 06–549
_________________

NATIONAL ASSOCIATION OF HOME BUILDERS,
ET AL., PETITIONERS
06–340 v.
DEFENDERS OF WILDLIFE ET AL.

ENVIRONMENTAL PROTECTION AGENCY,
PETITIONER
06–549 v.
DEFENDERS OF WILDLIFE ET AL.
ON WRITS OF CERTIORARI TO THE UNITED STATES COURT OF
APPEALS FOR THE NINTH CIRCUIT
[June 25, 2007]

JUSTICE STEVENS, with whom JUSTICE SOUTER, JUSTICE
GINSBURG, and JUSTICE BREYER join, dissenting.
These cases present a problem of conflicting “shalls.”
On the one hand, §402(b) of the Clean Water Act (CWA)
provides that the Environmental Protection Agency (EPA)
“shall” approve a State’s application to administer a Na
tional Pollution Discharge Elimination System (NPDES)
permitting program unless it determines that nine criteria
are not satisfied. 33 U. S. C. §1342(b). On the other hand,
shortly after the passage of the CWA, Congress enacted
§7(a)(2) of the Endangered Species Act of 1973 (ESA),
which commands that federal agencies “shall” insure that
their actions do not jeopardize endangered species. 16
U. S. C. §1536(a)(2).
When faced with competing statutory mandates, it is
our duty to give full effect to both if at all possible. See,
e.g., Morton v. Mancari, 417 U. S. 535, 551 (1974) (“[W]hen
2 NATIONAL ASSN. OF HOME BUILDERS v. DEFENDERS

OF WILDLIFE

STEVENS, J., dissenting

two statutes are capable of co-existence, it is the duty of
the courts, absent a clearly expressed congressional inten
tion to the contrary, to regard each as effective”). The
Court fails at this task. Its opinion unsuccessfully tries to
reconcile the CWA and ESA by relying on a federal regula
tion, 50 CFR §402.03 (2006), which it reads as limiting the
reach of §7(a)(2) to only discretionary federal actions, see
ante, at 17–19. Not only is this reading inconsistent with
the text and history of §402.03, but it is fundamentally
inconsistent with the ESA itself.
In the celebrated “snail darter” case, TVA v. Hill, 437
U. S. 153 (1978), we held that the ESA “reveals a con
scious decision by Congress to give endangered species
priority over the ‘primary missions’ of federal agencies,”
id., at 185. Consistent with that intent, Chief Justice
Burger’s exceptionally thorough and admirable opinion
explained that §7 “admits of no exception.” Id., at 173.
Creating precisely such an exception by exempting non
discretionary federal actions from the ESA’s coverage, the
Court whittles away at Congress’ comprehensive effort to
protect endangered species from the risk of extinction and
fails to give the Act its intended effect. After first giving
Hill the attention it deserves, I will comment further on
the irrelevance of §402.03 to these cases and offer other
available ways to give effect to both CWA and the ESA.
Having done so, I conclude by explaining why these cases
should be remanded to the EPA for further proceedings.
I
In Hill, we were presented with two separate questions:
(1) whether the ESA required a court to enjoin the opera
tion of the nearly completed Tellico Dam and Reservoir
Project because the Secretary of the Interior had deter
mined that its operation would eradicate a small endan
gered fish known as a snail darter; and (2) whether post
1973 congressional appropriations for the completion of
the Tellico Dam constituted an implied repeal of the ESA,
 Cite as: 551 U. S. ____ (2007) 3

STEVENS, J., dissenting

at least insofar as it applied to the Dam. 437 U. S., at 156.
More than 30 pages of our opinion explain our affirmative
answer to the first question, see id., at 156–188, but just
over four pages sufficed to explain our negative answer to
the second, see id., at 189–193. While it is our ruling on
the first question that is relevant to the cases before us, it
is our refusal to hold that the ESA itself had been impli
edly repealed that the majority strangely deems most
significant. See ante, at 21–22.
In answering Hill’s first question, we did not discuss
implied repeals. On the contrary, that portion of the
opinion contained our definitive interpretation of the ESA,
in which we concluded that “the language, history, and
structure of the [ESA] indicates beyond doubt that Con
gress intended endangered species to be afforded the
highest of priorities.” 437 U. S., at 174; see also id., at 177
(“ ‘The dominant theme pervading all Congressional dis
cussion of the proposed [ESA] was the overriding need to
devote whatever effort and resources were necessary to
avoid further diminution of national and worldwide wild
life resources’ ” (quoting Coggins, Conserving Wildlife
Resources: An Overview of the Endangered Species Act of
1973, 51 N. D. L. Rev. 315, 321 (1975) (emphasis added in
Hill))). With respect to §7 in particular, our opinion could
not have been any clearer. We plainly held that it “admits
of no exception.” 437 U. S., at 173 (emphasis added).1
Our opinion in Hill explained at length why §7 imposed
obligations on “all federal agencies” to ensure that “actions
authorized, funded, or carried out by them do not jeopard
——————
1 See also Babbitt v. Sweet Home Chapter, Communities for Great

Ore., 515 U. S. 687, 692 (1995) (“Section 7 requires federal agencies to
ensure that none of their activities, including the granting of licenses
and permits, will jeopardize the continued existence of endangered
species ‘or result in the destruction or adverse modification of habitat of
such species which is determined by the Secretary . . . to be critical’ ”
(emphasis added)).
4 NATIONAL ASSN. OF HOME BUILDERS v. DEFENDERS

OF WILDLIFE

STEVENS, J., dissenting

ize the continued existence of endangered species.” 437
U. S., at 173 (emphasis deleted; internal quotation marks
omitted). Not a word in the opinion stated or suggested
that §7 obligations are inapplicable to mandatory agency
actions that would threaten the eradication of an endan
gered species. Nor did the opinion describe the Tennessee
Valley Authority’s (TVA) attempted completion of the
Tellico Dam as a discretionary act. How could it? After
all, if the Secretary of the Interior had not declared the
snail darter an endangered species whose critical habitat
would be destroyed by operation of the Tellico Dam, the
TVA surely would have been obligated to spend the addi
tional funds that Congress appropriated to complete the
project.2 Unconcerned with whether an agency action was
mandatory or discretionary, we simply held that §7 of the
ESA
“reveals an explicit congressional decision to require
agencies to afford first priority to the declared na
tional policy of saving endangered species. The
pointed omission of the type of qualifying language
previously included in endangered species legislation
reveals a conscious decision by Congress to give en
dangered species priority over the ‘primary missions’

——————
2 The Court misreads this sentence and, in so doing, overreads our

decision in Hill. JUSTICE ALITO maintains that Hill held that the “acts
appropriating funds to the TVA . . . did not require the agency to use
any of the generally appropriated funds to complete the Tellico Dam
project.” Ante, at 23–24, n. 9. But Hill said no such thing. That case
only held that the subsequent appropriation of funds for the Tellico
Dam Project could not overcome the mandatory requirements of §7 of
the ESA; it did not hold that the TVA would not have been required to
spend any and all appropriated funds if the ESA had never been
passed. See Hill, 437 U. S., at 189–190. If the ESA had never been
enacted and did not stand in the way of the completion of the Tellico
Dam, there is no doubt that the TVA would have finished the project
that Congress had funded.
 Cite as: 551 U. S. ____ (2007) 5

STEVENS, J., dissenting

of federal agencies. ” Id., at 185 (emphasis added).3
The fact that we also concluded that the post-1973
congressional appropriations did not impliedly repeal the
ESA provides no support for the majority’s contention that
the obligations imposed by §7(a)(2) may be limited to
discretionary acts. A few passages from the relevant parts
of Hill belie that suggestion. After noting the oddity of
holding that the interest in protecting the survival of a
relatively small number of 3-inch fish “would require the
permanent halting of a virtually completed dam for which
Congress has expended more than $100 million,” we found
“that the explicit provisions of the Endangered Species Act
require precisely that result.” Id., at 172, 173. We then
continued:
“One would be hard pressed to find a statutory provi
sion whose terms were any plainer than those in §7 of
the Endangered Species Act. Its very words affirma
tively command all federal agencies ‘to insure that ac
tions authorized, funded, or carried out by them do
not jeopardize the continued existence’ of an endan
gered species or ‘result in the destruction or modifica
tion of habitat of such species . . . .’ ” Id., at 173 (quot
ing 16 U. S. C. §1536 (1976 ed.) (emphasis added in
Hill)).
We also reviewed the ESA’s history to identify a variety of
——————
3 The road not taken in Hill also helps to clarify our interpretation

that §7 was not limited to discretionary agency action. Throughout the
course of the litigation, the TVA insisted that §7 did not refer to “all the
actions that an agency can ever take.” Brief. for Petitioner in Tennessee
Valley Authority v. Hill, O.T. 1977, No. 76–1701, p. 26. Instead, the
TVA sought to restrict §7 to only those actions for “which the agency
has reasonable decision-making alternatives before it.” Ibid. We
rejected that narrow interpretation, stating that the only way to
sustain the TVA’s position would be to “ignore the ordinary meaning of
plain language.” Hill, 437 U. S., at 173.
6 NATIONAL ASSN. OF HOME BUILDERS v. DEFENDERS

OF WILDLIFE

STEVENS, J., dissenting

exceptions that had been included in earlier legislation
and unenacted proposals but were omitted from the final
version of the 1973 statute. We explained that earlier
endangered species legislation “qualified the obligation of
federal agencies,” but the 1973 Act purposefully omitted
“all phrases which might have qualified an agency’s re
sponsibilities.” 437 U. S., at 181, 182. Moreover, after
observing that the ESA creates only a limited number of
“hardship exemptions,” see 16 U. S. C. §1539—none of
which would apply to federal agencies—we applied the
maxim expressio unius est expression alterius to conclude
that “there are no exemptions in the Endangered Species
Act for federal agencies,”437 U. S., at 188.
Today, however, the Court countenances such an ex
emption. It erroneously concludes that the ESA contains
an unmentioned exception for nondiscretionary agency
action and that the statute’s command to enjoin the com
pletion of the Tellico Dam depended on the unmentioned
fact that the TVA was attempting to perform a discretion
ary act. But both the text of the ESA and our opinion in
Hill compel the contrary determination that Congress
intended the ESA to apply to “all federal agencies” and to
all “actions authorized, funded, or carried out by them.”
Id., at 173 (emphasis deleted).
A transfer of NPDES permitting authority under
§402(b) of the CWA is undoubtedly one of those “actions”
that is “authorized” or “carried out” by a federal agency.
See 16 U. S. C. §1536(b); 50 CFR §402.02 (defining “ac
tion” as “all activities or programs of any kind authorized,
funded, or carried out, in whole or in part, by Federal
agencies in the United States or upon the high seas.
Examples include, but are not limited to . . . actions di
rectly or indirectly causing modifications to the land,
water, or air”). It follows from Hill that §7(a)(2) applies to
such NPDES transfers—whether they are mandatory or
discretionary.
 Cite as: 551 U. S. ____ (2007) 7

STEVENS, J., dissenting

II
Given our unequivocal holding in Hill that the ESA has
“first priority” over all other federal action, 437 U. S., at
185, if any statute should yield, it should be the CWA.
But no statute must yield unless it is truly incapable of
coexistence. See, e.g., Morton, 417 U. S., at 551. There
fore, assuming that §402(b) of the CWA contains its own
mandatory command, we should first try to harmonize
that provision with the mandatory requirements of
§7(a)(2) of the ESA.
The Court’s solution is to rely on 50 CFR §402.03, which
states that “Section 7 and the requirements of this part
apply to all actions in which there is discretionary Federal
involvement or control.” The Court explains that this
regulation “harmonizes the statutes by giving effect to the
ESA’s no-jeopardy mandate whenever an agency has
discretion to do so, but by lifting that mandate when the
agency is forbidden from considering such extrastatutory
factors.” Ante, at 17. This is not harmony, and it certainly
isn’t effect. Rather than giving genuine effect to §7(a)(2),
the Court permits a wholesale limitation on the reach of
the ESA. Its interpretation of §402.03 conflicts with the
text and history of the regulation, as well as our interpre
tation of §7 in the “snail darter” case.
To begin with, the plain language of §402.03 does not
state that its coverage is limited to discretionary actions.
Quite the opposite, the most natural reading of the text is
that it confirms the broad construction of §7 endorsed by
our opinion in Hill. Indeed, the only way to read §402.03
in accordance with the facts of the case and our holding
that §7 “admits of no exception[s],” 437 U. S., at 173, is
that it eliminates any possible argument that the ESA
does not extend to situations in which the discretionary
federal involvement is only marginal.
The Court is simply mistaken when it says that it reads
§402.03 “to mean what it says: that §7(a)(2)’s no-jeopardy
8 NATIONAL ASSN. OF HOME BUILDERS v. DEFENDERS

OF WILDLIFE

STEVENS, J., dissenting

duty covers only discretionary agency actions . . . .” Ante,
at 21 (emphasis added). That is not, in fact, what §402.03
“says.” The word “only” is the Court’s addition to the text,
not the agency’s. Moreover, that text surely does not go on
to say (as the Court does) that the duty “does not attach to
actions (like the NPDES permitting transfer authoriza
tion) that an agency is required by statute to undertake
once certain specified triggering events have occurred.”
Ibid. If the drafters of the regulation had intended such a
far-reaching change in the law, surely they would have
said so by using language similar to that which the Court
uses today.
Nothing in the proceedings that led to the promulgation
of the regulation suggests any reason for limiting the pre
existing understanding of the scope of §7’s coverage. EPA
codified the current version of §402.03 in 1986 as part of a
general redrafting of ESA regulations. In the 1983 Notice
of Proposed Rulemaking, the proposed version of §402.03
stated that Ҥ7 and the requirements of this Part apply to
all actions in which there is Federal involvement or con
trol.” 48 Fed. Reg. 29999 (1983). Without any explana
tion, the final rule inserted the word “discretionary” before
“Federal involvement or control.” 51 Fed. Reg. 19958
(1986).4 Clearly, if the Secretary of the Interior meant to
limit the pre-existing understanding of the scope of the
coverage of §7(a)(2) by promulgating this regulation, that
intent would have been mentioned somewhere in the text
of the regulations or in contemporaneous comment about
them. See National Cable & Telecommunications Assn. v.
——————
4 See also Kilbourne, The Endangered Species Act Under the Micro

scope: A Closeup Look From A Litigator’s Perspective, 21 Envtl. L. 499,
529 (1991) (noting that the agency did not explain the addition of the
word “discretionary”); Weller, Limiting the Scope of the Endangered
Species Act: Discretionary Federal Involvement or Control Under
Section 402.03, 5 Hastings W.-Nw. J. Envtl. L. & Pol’y 309, 311, 334
(Spring 1999) (same)
 Cite as: 551 U. S. ____ (2007) 9

STEVENS, J., dissenting

Brand X Internet Services, 545 U. S. 967, 1001 (2005)
(holding that an agency is free within “the limits of rea
soned interpretation to change course” only if it “ade
quately justifies the change”); Motor Vehicle Mfrs. Assn. of
United States, Inc. v. State Farm Mut. Automobile Ins. Co.,
463 U. S. 29, 48 (1983) (“We have frequently reiterated
that an agency must cogently explain why it has exercised
its discretion in a given manner”). Yet, the final rule said
nothing about limiting the reach of §7 or our decision in
Hill. Nor did it mention the change from the notice of
proposed rulemaking. I can only assume, then, that the
regulation does mean what both it and the notice of pro
posed rulemaking says: Section 7(a)(2) applies to discre
tionary federal action, but not only to discretionary action.
The only explanation the agency provided for §402.03
was the following:
“This section, which explains the applicability of sec
tion 7, implicitly covers Federal activities within the
territorial jurisdiction of the United States and upon
the high seas as a result of the definition of ‘action’ in
§402.02. The explanation for the scope of the term
‘action’ is provided in the discussion under §402.01
above.” 51 Fed. Reg. 19937.
This statement directs us to two sources: the definition of
“action” in §402.02 and the “explanation for the scope of
the term ‘action’ ” in §402.01. Ibid. Both confirm that
there was no intent to draw a distinction between discre
tionary and nondiscretionary actions.
Section 402.02 provides in relevant part:
“Action means all activities or programs of any kind
authorized, funded, or carried out, in whole or in part,
by Federal agencies in the United States or upon the
high seas. Examples include, but are not limited to:
“(a) actions intended to conserve listed species or
their habitat;
10 NATIONAL ASSN. OF HOME BUILDERS v. DEFENDERS
OF WILDLIFE
STEVENS, J., dissenting

“(b) the promulgation of regulations . . . ” (second
and third emphases added.)
Actions in either of the described sub-categories are some
times mandatory and sometimes discretionary. Likewise,
as the italicized portions indicate, the term “action” ex
pressly refers to “all” agency activities or programs “of any
kind,” regardless of whether they are discretionary or
mandatory. By reading the term “discretionary” as a
limitation on “action,” the Court creates a contradiction in
the EPA’s own regulation.5
As for the final rule’s explanation for the scope of the
term ’action’ in §402.01, that too is fully consistent with
my interpretation of §402.03. That explanation plainly
states that “all Federal actions including ‘conservations
programs’ are subject to the consultation requirements of
section 7(a)(2) if they ‘may affect’ listed species or their
critical habitats.” 51 Fed. Reg. 19929 (emphasis added).
The regulation does not say all “discretionary” federal
actions, nor does it evince an intent to limit the scope of
§7(a)(2) in any way. Rather, it just restates that the ESA
applies to “all” federal actions, just as the notice of pro
——————
5 Petitioner National Association of Home Builders (NAHB) points to

the following language from the final rule as an indication that §7 only
applies to discretionary action: “ ‘a Federal agency’s responsibility
under section 7(a)(2) permeates the full range of discretionary authority
held by that agency.’ ” Brief for Petitoioners NAHB et al. 32 (quoting 51
Fed. Reg. 19937). However, that language is found in a different
section of the Final Rule—the section describing the definition of
“ ‘[r]easonable and prudent alternatives’ ” under 50 CFR §402.02. When
put in its proper context, the cited language simply indicates that any
“reasonable and prudent alternative” may involve the “maximum
exercise federal agency authority when to do so is necessary, in the
opinion of the Service, to avoid jeopardy.” 51 Fed. Reg. 19926. If that
isn’t enough, the quoted text supports my reading of §402.03 even on
petitioner’s reading. By indicating that an agency’s §7(a)(2) responsi
bility “permeates the full range” of its discretionary authority, EPA
confirmed that the ESA covers the all discretionary actions.
 Cite as: 551 U. S. ____ (2007) 11

STEVENS, J., dissenting

posed rulemaking did. This explanation of the scope of the
word “action” is therefore a strong indication that the
Court’s reading of “discretionary” is contrary to its in
tended meaning.
An even stronger indication is the fact that at no point
in the administrative proceedings in these cases did EPA
even mention it.6 As an initial matter, it is worth empha
sizing that even if EPA had relied on §402.03, its interpre
tation of the ESA would not be entitled to deference under
Chevron U. S. A. Inc. v. Natural Resources Defense Coun
cil, Inc., 467 U. S. 837 (1984), because it is not charged
with administering that statute, id., at 844 (“We have long
recognized that considerable weight should be accorded to
an executive department’s construction of a statutory
scheme it is entrusted to administer.” (emphasis added));
Department of Treasury v. FLRA, 837 F. 2d 1163, 1167
(CADC 1988) (“[W]hen an agency interprets a statute
other than that which it has been entrusted to administer,
its interpretation is not entitled to deference”). The De
partments of the Interior and Commerce, not EPA, are
charged with administering the ESA. See Babbitt v. Sweet
Home Chapter, Communities for Great Ore., 515 U. S.,
687, 703–704 (1995). And EPA has conceded that the
Department of the Interior’s biological opinion “did not
discuss 50 CFR. 402.03, and it did not address the ques
tion whether the consultation that produced the [biological
opinion] was required by the ESA.” Pet. for Cert. in
No. 06–549, p. 24; see App. 77–124 (never mentioning
§402.03). Left with this unfavorable administrative re
——————
6 EPA also did not rely on §402.03 in the Court of Appeals. See 420

F. 3d 946, 968 (“EPA makes no argument that its transfer decision was
not a ‘discretionary’ one within the meaning of 50 CFR §402.03. . . .
We may not affirm the EPA’s transfer decision on grounds not relied
upon by the agency. As the EPA evidently does not regard §402.03 as
excluding the transfer decision, we should not so interpret the regula
tions.” (citations omitted)).
12 NATIONAL ASSN. OF HOME BUILDERS v. DEFENDERS
OF WILDLIFE
STEVENS, J., dissenting

cord, EPA can only lean on the fact that the Department of
the Interior has recently “clarified” its position regarding
§402.03 in a different administrative proceeding. See Pet.
for Cert. in No. 06–549, pp. 24–25; id., at 26 (“The recent
F[ish and Wildlife Service] and N[ational Marine Fisheries
Service] communications regarding Alaska’s pending
transfer application reflect those agencies’ considered
interpretations . . . of [50 CFR] 402.03”); App. to Pet. for
Cert. in No. 06–340, pp. 103a–116a; see also ante, at 12
n. 5. We have long held, however, that courts may not
affirm an agency action on grounds other than those
adopted by the agency in the administrative proceedings.
See SEC v. Chenery Corp., 318 U. S. 80, 87 (1943). The
majority ignores this hoary principle of administrative law
and substitutes a post-hoc interpretation of §7(a)(2) and
§402.03 for that of the relevant agency. For that reason
alone, these cases should be remanded to the agency. And
for the other reasons I have given, §402.03 cannot be used
to harmonize the CWA and the ESA.
III
There are at least two ways in which the CWA and the
ESA can be given full effect without privileging one stat
ute over the other.
A
The text of §7(a)(2) itself provides the first possible way
of reconciling that provision with §402(b) of the CWA.
The subsection reads:
“Each Federal agency shall, in consultation with and
with the assistance of the Secretary, insure that any
action authorized, funded, or carried out by such
agency (hereinafter in this section referred to as an
‘agency action’) is not likely to jeopardize the contin
ued existence of any endangered species or threatened
species or result in the destruction or adverse modifi
 Cite as: 551 U. S. ____ (2007) 13

STEVENS, J., dissenting

cation of habitat of such species which is determined
by the Secretary, after consultation as appropriate
with affected States, to be critical, unless such agency
has been granted an exemption for such action by the
Committee pursuant to subsection (h) of this section.”
16 U. S. C. §1536(a)(2) (emphasis added).
The Court is certainly correct that the use of the word
“shall” in §7(a)(2) imposes a mandatory requirement on
the federal agencies. See ante, at 14. It is also correct
that the ESA’s “mandate is to be carried out through
consultation and may require the agency to adopt an
alternative course of action.” Ante, at 15. The Court is too
quick to conclude, however, that this consultation re
quirement creates an irreconcilable conflict between this
provision and §402(b) of the CWA. It rushes to this flawed
judgment because of a basic conceptual error—an error
that is revealed as early as the first paragraph of its opin
ion. Rather than attempting to find a way to give effect to
§7(a)(2)’s consultation requirement, the Court frames the
question presented as “whether §7(a)(2) effectively oper
ates as a tenth criterion on which the transfer of permit
ting power under the first statute must be conditioned. ”
Ante, at 1–2. The Court is not alone in this. The author of
the Ninth Circuit opinion below also stated that the ESA
“adds one requirement to the list of considerations under
the Clean Water Act permitting transfer provision.” 450
F. 3d, at 404 n. 2 (2006) (Berzon, J., concurring in denial of
rehearing en banc) (emphasis in original). But while the
ESA does mandate that the relevant agencies “consul[t]”
with the Interior Department, that consultation process
also provides a way for the agencies to give effect to both
statutes.
The first step in the statutory consultation process is to
identify whether any endangered species will be affected
by an agency action. An agency proposing a particular
14 NATIONAL ASSN. OF HOME BUILDERS v. DEFENDERS
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STEVENS, J., dissenting

action, such as an NPDES transfer, will typically ask the
Secretary of the Interior whether any listed species may
be present in the area of the proposed action and whether
that action will “affect” those species. See 16 U. S. C.
§1536(c). It is entirely possible that no listed species will
be affected, and any anticipated conflict between the ESA
and another statute will have been avoided at this thresh
old stage. If, however, the Secretary determines that a
proposed action may affect an endangered species or its
critical habitat, the agency must formally consult with the
Secretary. This consultation culminates in the issuance of
a “biological opinion,” which “detail[s] how the agency
action affects the species or its critical habitat.”
§1536(b)(3)(A); see also 50 CFR §402.14(h). Even at this
stage, it is still possible that formal consultation will
reveal that the agency action will not jeopardize any spe
cies. See, e.g., 63 Fed. Reg. 51199 (1998) (noting that FWS
rendered a “no jeopardy” finding with respect to the trans
fer of permitting authority to Texas).
If the biological opinion concludes that the agency action
would put a listed species in jeopardy, however, the ESA
contains a process for resolving the competing demands of
agency action and species protection. The ESA provides
that “the Secretary shall suggest those reasonable and
prudent alternatives which he believes would not violate
subsection (a)(2) and can be taken by the Federal agency
or applicant in implementing the agency action.” 16
U. S. C. §1536(b)(3)(A); see also 50 CFR §402.14(h)(3).
The agency’s regulations define “[r]easonable and prudent
alternatives” as
“alternative actions identified during formal consul
tation that can be implemented in a manner consis
tent with the intended purpose of the action, that can
be implemented consistent with the scope of the Fed
eral agency’s legal authority and jurisdiction, that is
 Cite as: 551 U. S. ____ (2007) 15

STEVENS, J., dissenting

economically and technologically feasible, and that the
Director [of FWS] believes would avoid the likelihood
of jeopardizing the continued existence of listed spe
cies or resulting in the destruction or adverse modifi
cation of critical habitat. ” 50 CFR §402.02.
Thus, in the face of any conflict between the ESA and
another federal statute, the ESA and its implementing
regulations encourage federal agencies to work out a
reasonable alternative that would let the proposed action
move forward “consistent with [its] intended purpose” and
the agency’s “legal authority,” while also avoiding any
violation of §7(a)(2).
When applied to the NPDES transfer program, the
“reasonable and prudent alternatives” process would
enable EPA and the Department of the Interior to develop
a substitute that would allow a transfer of permitting
authority and would not jeopardize endangered species.
Stated differently, the consultation process would gener
ate an alternative course of action whereby the transfer
could still take place—as required by §402(b) of the
CWA—but in such a way that would honor the mandatory
requirements of §7(a)(2) of the ESA. This should come as
no surprise to EPA, as it has engaged in pre-transfer
consultations at least six times in the past and has stated
that it is not barred from doing so by the CWA.7
Finally, for the rare case in which no “reasonable and
prudent alternative” can be found, Congress has provided
——————
7 See, e.g., 63 Fed. Reg. 51199 (1998) (approving Texas’ application to

administer the NPDES program after consultation with FWS and
stating that “EPA believes that section 7 does apply” to EPA’s action);
61 Fed. Reg. 65053 (1996) (approving Oklahoma’s NPDES application
after consultation with FWS and stating that “EPA’s approval of the
State permitting program under section 402 of the Clear Water Act is a
federal action subject to [§7’s consultation] requirement”); see also Tr.
of Oral Arg. 5 (conceding that EPA conducted six pre-transfer consulta
tions in the past).
16 NATIONAL ASSN. OF HOME BUILDERS v. DEFENDERS
OF WILDLIFE
STEVENS, J., dissenting

yet another mechanism for resolving any conflicts between
the ESA and a proposed agency action. In 1978, shortly
after our decision in Hill, Congress amended the ESA to
create the “Endangered Species Committee,” which it
authorized to grant exemptions from §7(a)(2). 16 U. S. C.
§1536(e). Because it has the authority to approve the
extinction of an endangered species, the Endangered
Species Committee is colloquially described as the “God
Squad” or “God Committee.” In light of this weighty
responsibility, Congress carefully laid out requirements
for the God Committee’s membership,8 procedures,9 and
the factors it must consider in deciding whether to grant
an exemption.10

——————
8 The Endangered Species Committee is composed of six high-ranking

federal officials and a representative from each affected State ap
pointed by the President. See 16 U. S. C. §1536(e)(3).
9 See 16 U. S. C. §§1536(e)–(l).
10 Title 16 U. S. C. §1536(h)(1) provides:

“The Committee shall grant an exemption from the requirements of
subsection (a)(2) for an agency action if, by a vote of not less than five of
its members voting in person—
“(A) it determines on the record, based on the report of the Secretary,
the record of the hearing held under subsection (g)(4) and on such other
testimony or evidence as it may receive, that—
“(i) there are no reasonable and prudent alternatives to the agency
action;
“(ii) the benefits of such action clearly outweigh the benefits of
alternative courses of action consistent with conserving the species or
its critical habitat, and such action is in the public interest;
“(iii) the action is of regional or national significance; and
“(iv) neither the Federal agency concerned nor the exemption appli
cant made any irreversible or irretrievable commitment of resources
prohibited by subsection (d); and
“(B) it establishes such reasonable mitigation and enhancement
measures, including, but not limited to, live propagation, transplan
tation, and habitat acquisition and improvement, as are necessary
and appropriate to minimize the adverse effects of the agency action
upon the endangered species, threatened species, or critical habitat
concerned.”
 Cite as: 551 U. S. ____ (2007) 17

STEVENS, J., dissenting

As the final arbiter in situations in which the ESA
conflicts with a proposed agency action, the God Commit
tee embodies the primacy of the ESA’s mandate and
serves as the final mechanism for harmonizing that Act
with other federal statutes. By creating this Committee,
Congress recognized that some conflicts with the ESA may
not be capable of resolution without having to forever
sacrifice some endangered species. At the same time, the
creation of this last line of defense reflects Congress’ view
that the ESA should not yield to another federal action
except as a final resort and except when authorized by
high level officials after serious consideration. In short,
when all else has failed and two federal statutes are inca
pable of resolution, Congress left the choice to the Com
mittee—not to this Court; it did not limit the ESA in the
way the majority does today.
B
EPA’s regulations offer a second way to harmonize the
CWA with the ESA. After EPA has transferred NPDES
permitting authority to a State, the agency continues to
oversee the State’s permitting program. See Arkansas v.
Oklahoma, 503 U. S. 91, 105 (1992) (“Congress preserved
for the Administrator broad authority to oversee state
permit programs”). If a state permit is “outside the guide
lines and the requirements” of the CWA, EPA may object
to it and block its issuance. See 33 U. S. C. §1342(d)(2); 66
Fed. Reg. 11206 (2001). Given these ongoing responsibili
ties, EPA has enacted a regulation that requires a State to
enter into a Memorandum of Agreement (MOA) that sets
forth the particulars of the agency’s oversight duties. See
40 CFR §123.24(a) (2006).
The regulation governing MOAs contains several de
tailed requirements. For instance, the regulation states
that an MOA must contain “[p]rovisions specifying classes
and categories of permit applications, draft permits and
18 NATIONAL ASSN. OF HOME BUILDERS v. DEFENDERS
OF WILDLIFE
STEVENS, J., dissenting

proposed permits that the State will send to the [EPA]
Regional Administrator for review, comment and, where
applicable, objection,” §123.24(b)(2); “[p]rovisions specify
ing the frequency and content of reports, documents and
other information which the State is required to submit to
the EPA,” §123.24(b)(3); and “[p]rovisions for coordination
of compliance monitoring activities by the State and by
EPA,” §123.24(b)(4)(i). More generally, the regulation
provides that an MOA “may include other terms, condi
tions, or agreements” that are “relevant to the administra
tion and enforcement of the State’s regulatory program.”
§123.24(a). Under the MOA regulation, furthermore, EPA
will not approve any MOA that restricts its statutory
oversight responsibility. Ibid.
Like the §7(a)(2) consultation process described above,
MOAs provide a potential mechanism for giving effect to
§7 of the ESA while also allowing the transfer of permit
ting authority to a State. It is important to remember
that EPA must approve an MOA prior to the transfer of
NPDES authority. As such, EPA can use—and in fact has
used—the MOA process to structure its later oversight in
a way that will allow it to protect endangered species in
accordance with §7(a)(2) of the ESA. EPA might negotiate
a provision in the MOA that would require a State to
abide by the ESA requirements when issuing pollution
permits. See Brief for American Fisheries Society et al. as
Amici Curiae 28. (“In the Maine MOA, for example, EPA
and the state agreed that state permits would protect
ESA-listed species by ensuring compliance with state
water quality standards”). Alternatively, “EPA could
require the state to provide copies of draft permits for
discharges in particularly sensitive habitats such as those
of ESA-listed species or for discharges that contain a
pollutant that threatens ESA-listed wildlife.” Id., at 10.
Or the MOA might be drafted in a way that would allow
the agency to object to state permits that would jeopardize
 Cite as: 551 U. S. ____ (2007) 19

STEVENS, J., dissenting

any and all endangered species. See id., at 28 (explaining
that the Maine MOA includes a provision allowing EPA to
“object to any state permit that risks harm to a listed
species by threatening water quality”). These are just
three of many possibilities. I need not identify other ways
EPA could use the MOA process to comply with the ESA;
it is enough to observe that MOAs provide a straightfor
ward way to give the ESA its full effect without restricting
§7(a)(2) in the way the Court does.
IV
As discussed above, I believe that the Court incorrectly
restricts the reach of §7(a)(2) to discretionary federal
actions. See Part II, supra. Even if such a limitation
were permissible, however, it is clear that EPA’s author
ity to transfer permitting authority under §402(b) is
discretionary.11
The EPA Administrator’s authority to approve state
permit programs pursuant to §402(b) of the CWA does not
even fit within the Court’s description of the category of
mandatory actions that the Court holds are covered by the
ESA. In the Court’s words, that category includes actions
“that an agency is required by statute to undertake once
certain specified triggering events have occurred.” Ante,
at 22. The “triggering event” for EPA’s approval is simply
the filing of a satisfactory description of the State’s pro
posed program. See 33 U. S. C. §1342(b). The statute
then commands that the EPA Administrator “shall ap
prove” the submitted program unless he determines that
state law does not satisfy nine specified conditions. Those
conditions are not “triggering events”; they are potential
objections to the exercise of the Administrator’s authority.
What is more, §402(b) is a perfect example of why our

——————
11 Because it is quite lengthy, I include the full text of §402(b) in an

appendix to this dissent.
20 NATIONAL ASSN. OF HOME BUILDERS v. DEFENDERS
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STEVENS, J., dissenting

analysis should not end simply because a statute uses the
word “shall.” Instead, we must look more closely at its
listed criteria to determine whether they allow for discre
tion, despite the use of “shall.” After all, as then-Justice
Rehnquist’s dissenting opinion in the “snail darter” case
explains, a federal statute using the word “shall” will
sometimes allow room for discretion. See Hill, 437 U. S. at
211–212 (Rehnquist, J., dissenting).12 In these cases,
there is significant room for discretion in EPA’s evaluation
of §402(b)’s nine conditions. The first criterion, for exam
ple, requires the EPA Administrator to examine five other
statutes and ensure that the State has adequate authority
to comply with each. 33 U. S. C. §1342(b)(1)(A). One of
those five statutes, in turn, expressly directs the Adminis
trator to exercise his “judgment.” §1312. Even the Court
acknowledges that EPA must exercise “some judgment in
determining whether a State has demonstrated that it has
the authority to carry out §402(b)’s enumerated statutory
criteria.” Ante, at 24. However, in the very same breath,
the Court states that the dispositive fact is that “the stat
ute clearly does not grant it the discretion to add another
entirely separate prerequisite to that list.” Ibid. This
reasoning flouts the Court’s own logic. Under the Court’s
reading of §402.03, §7(a)(2) applies to discretionary federal
actions of any kind. The Court plainly acknowledges that
EPA exercises discretion when deciding whether to trans
fer permitting authority to a State. If we are to take the

——————
12 See Gutierrez de Martinez v. Lamagno, 515 U. S. 417, 432–433, n. 9

(1995) (“Though ‘shall’ generally means ‘must,’ legal writers sometimes
use, or misuse, ‘shall’ to mean ‘should,’ ‘will,’ or even ‘may.’ See D.
Mellinkoff, Mellinkoff's Dictionary of American Legal Usage 402–403
(1992) (‘shall’ and ‘may’ are ‘frequently treated as synonyms’ and their
meaning depends on context); B. Garner, Dictionary of Modern Legal
Usage 939 (2d ed. 1995) (“Courts in virtually every English-speaking
jurisdiction have held—by necessity—that shall means may in some
contexts, and vice versa.’)”).
 Cite as: 551 U. S. ____ (2007) 21

STEVENS, J., dissenting

Court’s approach seriously, once any discretion has been
identified—as it has here—§7(a)(2) must apply.13
The MOA regulation described in Part III–B, supra, also
demonstrates that an NPDES transfer is not as ministe

——————
13 The Court also claims that the “basic principle announced in” De

partment of Transportation v. Public Citizen, 541 U. S. 752 (2004),—
“that an agency cannot be considered the legal ‘cause’ of an action that
it has no statutory discretion not to take”—supports its reliance on
§402.03. Ante, at 20. First of all, the Court itself recognizes that it
must distance itself from that case, ibid., because Public Citizen dealt
with a procedural requirement under the National Environmental
Policy Act (NEPA), not a substantive requirement like that imposed by
§7(a)(2) of the ESA, see TVA v. Hill, 437 U. S. 158, 188, n. 34 (1978)
(holding that NEPA cases are “completely inapposite” to the ESA
context). What the Court does not recognize, however, is that what it
views as the “basic principle” of Public Citizen is stated too broadly and
therefore inapplicable to this case. Ante, at 20.
Our decision in Public Citizen turned on what we called “a critical
feature of the case”: that the Federal Motor Carrier Safety Administra
tion (FMCSA) had “no ability to countermand” the President’s lifting a
moratorium that prohibited certain motor carriers from obtaining
authority to operate within the United States. 541 U. S., at 766. Once
the President decided to lift that moratorium, and once the relevant
vehicles had entered the United States, FMCSA was required by
statute to register the vehicles if certain conditions were met. Ibid.
(“Under FMCSA’s entirely reasonable reading of this provision, it must
certify any motor carrier that can show that it is willing and able to
comply with the various substantive requirements for safety and
financial responsibility contained in DOT regulations; only the morato
rium prevented it from doing so for Mexican motor carriers before 2001”
(emphasis deleted)). Therefore, any potential NEPA concerns were
generated by another decisionmaker, the President, and not the
FMCSA. Here, by contrast, EPA is not required to act ministerially
once another person or agency has made a decision. Instead, EPA must
exercise its own judgment when considering the transfer of NPDES
authority to a State; it also has its own authority to deny such a trans
fer. Any effect on endangered species will be caused, even if indirectly,
by the agency’s own decision to transfer NPDES authority. Cf. 50 CFR
§402.02 (providing that the ESA will apply to all agency activities that
“directly or indirectly caus[e] modifications to the land, water, or air”
(emphasis added)).
22 NATIONAL ASSN. OF HOME BUILDERS v. DEFENDERS
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STEVENS, J., dissenting

rial a task as the Court would suggest. The agency retains
significant discretion under §123.24 over the content of an
MOA, which of course must be approved prior to a trans
fer. For instance, EPA may require a State to file reports
on a weekly basis or a monthly basis. It may require a
State to submit only certain classes and categories of
permit applications. And it may include any additional
terms and conditions that are relevant to the enforcement
of the NPDES program. There is ample room for judg
ment in all of these areas, and EPA has exercised such
judgment in the past when approving MOAs from many
States. See, e.g., Approval of Application by Maine to
Administer the NPDES Program, 66 Fed. Reg. 12791,
(2001); Approval of Application by Maine to Administer
the NPDES Program; Texas, 63 Fed. Reg. 51165 (1998).
In fact, in an earlier case raising a question similar to
this one, see American Forest & Paper Assn. v. EPA, 137
F. 3d 291, 298–299 (CA5 1998), EPA itself explained how
40 CFR §123.24 gives it discretion over the approval of a
State pollution control program, see Brief for EPA in No.
96–60874 (CA5). Arguing that “[i]ndicia of discretionary
involvement or control abound in [its] regulations,” the
agency listed its MOA regulation as a prime example.14
Again, because EPA’s approval of a State application to
administer an NPDES program entails significant—
indeed, abounding—discretion, I would find that §7(a)(2)
of the ESA applies even under the Court’s own flawed
theory of these cases.
——————
14 EPA also discussed several other regulations that give it discretion.
For example, under 40 CFR §123.61(b), EPA is required to solicit public
comments on a State’s transfer application, and it must “approve or
disapprove the program” after “taking into consideration all comments
received.” As EPA explained in its Fifth Circuit brief, if it “were simply
acting in a ministerial fashion, such weighing of the merits of public
comments would be unnecessary.” Brief for EPA in No. 96–60874
(CA5).
 Cite as: 551 U. S. ____ (2007) 23

STEVENS, J., dissenting

V
Mindful that judges must always remain faithful to the
intent of the legislature, Chief Justice Burger closed his
opinion in the “snail darter” case with a reminder that
“[o]nce the meaning of an enactment is discerned and its
constitutionality determined, the judicial process comes to
an end.” Hill, 437 U. S., at 194. This Court offered a
definitive interpretation of the Endangered Species Act
nearly 30 years ago in that very case. Today the Court
turns its back on our decision in Hill and places a great
number of endangered species in jeopardy, including the
cactus ferruginous pygmy-owl and Pima pineapple cactus
at issue here. At the risk of plagiarizing Chief Justice
Burger’s fine opinion, I think it is appropriate to end my
opinion just as he did—with a quotation attributed to Sir
Thomas More that has as much relevance today as it did
three decades ago. This quotation illustrates not only the
fundamental character of the rule of law embodied in §7 of
the ESA but also the pernicious consequences of official
disobedience of such a rule. Repetition of that literary
allusion is especially appropriate today:
“The law, Roper, the law. I know what’s legal, not
what’s right. And I’ll stick to what’s legal. . . . I’m not
God. The currents and eddies of right and wrong,
which you find such plain-sailing, I can’t navigate, I’m
no voyager. But in the thickets of the law, oh there
I’m a forester. . . . What would you do? Cut a great
road through the law to get after the Devil? . . . And
when the last law was down, and the Devil turned
round on you—where would you hide, Roper, the laws
all being flat? . . . This country's planted thick with
laws from coast to coast—Man’s laws, not God’s—and
if you cut them down . . . d’you really think you could
stand upright in the winds that would blow then? . . .
Yes, I’d give the Devil benefit of law, for my own
24 NATIONAL ASSN. OF HOME BUILDERS v. DEFENDERS
OF WILDLIFE
STEVENS, J., dissenting

safety’s sake.” R. Bolt, A Man for All Seasons, Act I,
p. 147 (Three Plays, Heinemann ed. 1967) (quoted in
Hill, 437 U. S., at 195).
Although its reasons have shifted over time, at both
the administrative level and in the federal courts, EPA
has insisted that the requirements of §7(a)(2) of the ESA
do not apply to its decision to transfer permitting author
ity under §402(b) of the CWA. See App. 114; Brief for
Petitioner EPA 16, 42. As I have explained above, that
conclusion is contrary to the text of §7(a)(2), our decision
in the TVA v. Hill, and the regulation on which the
agency has since relied and upon which the Court relies
on today. Accordingly, I would hold that EPA’s decision
was arbitrary and capricious under the Administrative
Procedure Act, see 5 U. S. C. §706(2)(A), and would re
mand to the agency for further proceedings consistent
with this opinion.
I respectfully dissent.
 Cite as: 551 U. S. ____ (2007) 25

STEVENS, J., dissenting
Appendix to opinion of STEVENS, J.

APPENDIX TO OPINION OF STEVENS, J.
33 U. S. C. §1342(b)
“(b) State permit programs.
“At any time after the promulgation of the guidelines
required by subsection (i)(2) of section 1314 of this title,
the Governor of each State desiring to administer its own
permit program for discharges into navigable waters
within its jurisdiction may submit to the Administrator a
full and complete description of the program it proposes to
establish and administer under State law or under an
interstate compact. In addition, such State shall submit a
statement from the attorney general (or the attorney for
those State water pollution control agencies which have
independent legal counsel), or from the chief legal officer
in the case of an interstate agency, that the laws of such
State, or the interstate compact, as the case may be, pro
vide adequate authority to carry out the described pro
gram. The Administrator shall approve each submitted
program unless he determines that adequate authority
does not exist:
“(1) To issue permits which—
“(A) apply, and insure compliance with, any applicable
requirements of sections 1311, 1312, 1316, 1317, and 1343
of this title;
“(B) are for fixed terms not exceeding five years; and
“(C) can be terminated or modified for cause including,
but not limited to, the following:
“(i) violation of any condition of the permit;
“(ii) obtaining a permit by misrepresentation, or failure
to disclose fully all relevant facts;
“(iii) change in any condition that requires either a
temporary or permanent reduction or elimination of the
permitted discharge;
“(D) control the disposal of pollutants into wells;
“(2)(A) To issue permits which apply, and insure com
26 NATIONAL ASSN. OF HOME BUILDERS v. DEFENDERS
OF WILDLIFE
STEVENS, J., dissenting
Appendix to opinion of STEVENS, J.

pliance with, all applicable requirements of section 1318 of
this title; or
“(B) To inspect, monitor, enter, and require reports to at
least the same extent as required in section 1318 of this
title;
“(3) To insure that the public, and any other State the
waters of which may be affected, receive notice of each
application for a permit and to provide an opportunity for
public hearing before a ruling on each such application;
“(4) To insure that the Administrator receives notice of
each application (including a copy thereof) for a permit;
“(5) To insure that any State (other than the permitting
State), whose waters may be affected by the issuance of a
permit may submit written recommendations to the per
mitting State (and the Administrator) with respect to any
permit application and, if any part of such written recom
mendations are not accepted by the permitting State, that
the permitting State will notify such affected State (and
the Administrator) in writing of its failure to so accept
such recommendations together with its reasons for so
doing;
“(6) To insure that no permit will be issued if, in the
judgment of the Secretary of the Army acting through the
Chief of Engineers, after consultation with the Secretary
of the department in which the Coast Guard is operating,
anchorage and navigation of any of the navigable waters
would be substantially impaired thereby;
“(7) To abate violations of the permit or the permit
program, including civil and criminal penalties and other
ways and means of enforcement;
“(8) To insure that any permit for a discharge from a
publicly owned treatment works includes conditions to
require the identification in terms of character and volume
of pollutants of any significant source introducing pollut
ants subject to pretreatment standards under section
1317(b) of this title into such works and a program to
 Cite as: 551 U. S. ____ (2007) 27

STEVENS, J., dissenting
Appendix to opinion of STEVENS, J.

assure compliance with such pretreatment standards by
each such source, in addition to adequate notice to the
permitting agency of (A) new introductions into such
works of pollutants from any source which would be a new
source as defined in section 1316 of this title if such source
were discharging pollutants, (B) new introductions of
pollutants into such works from a source which would be
subject to section 1311 of this title if it were discharging
such pollutants, or (C) a substantial change in volume or
character of pollutants being introduced into such works
by a source introducing pollutants into such works at the
time of issuance of the permit. Such notice shall include
information on the quality and quantity of effluent to be
introduced into such treatment works and any anticipated
impact of such change in the quantity or quality of effluent
to be discharged from such publicly owned treatment
works; and
(9) To insure that any industrial user of any publicly
owned treatment works will comply with sections 1284(b),
1317, and 1318 of this title.
 Cite as: 551 U. S. ____ (2007) 1

BREYER, J., dissenting

SUPREME COURT OF THE UNITED STATES
_________________

Nos. 06–340 and 06–549
_________________

NATIONAL ASSOCIATION OF HOME BUILDERS,
ET AL., PETITIONERS
06–340 v.
DEFENDERS OF WILDLIFE ET AL.

ENVIRONMENTAL PROTECTION AGENCY,
PETITIONER
06–549 v.
DEFENDERS OF WILDLIFE ET AL.
ON WRITS OF CERTIORARI TO THE UNITED STATES COURT OF
APPEALS FOR THE NINTH CIRCUIT
[June 25, 2007]

JUSTICE BREYER, dissenting.
I join JUSTICE STEVENS’ dissent, while reserving judg
ment as to whether §7(a)(2) of the Endangered Species Act
of 1973, 16 U. S. C. §1536(a)(2), really covers every possi
ble agency action even of totally unrelated agencies—such
as, say, a discretionary determination by the Internal
Revenue Service whether to prosecute or settle a particu
lar tax liability, see 26 U. S. C. §7121.
At the same time I add one additional consideration in
support of his (and my own) dissenting views. The Court
emphasizes that “[b]y its terms, the statutory language [of
§402(b) of the Clean Water Act, 33 U. S. C. §1342(b)] is
mandatory and the list exclusive; if the nine specified
criteria are satisfied, the EPA does not have the discretion
to deny a transfer application.” Ante, at 14 (emphasis
added). My own understanding of agency action leads me
to believe that the majority cannot possibly be correct in
2 NATIONAL ASSN. OF HOME BUILDERS v. DEFENDERS

OF WILDLIFE

BREYER, J., dissenting

concluding that the structure of §402(b) precludes applica
tion of §7(a)(2) to the EPA’s discretionary action. See ante,
at 19–21 (STEVENS, J., dissenting). That is because grants
of discretionary authority always come with some implicit
limits attached. See L. Jaffe, Judicial Control of Adminis
trative Action 359 (1965) (discretion is “a power to make a
choice” from a “permissible class of actions”). And there
are likely numerous instances in which, prior to, but not
after, the enactment of §7(a)(2), the statute might have
implicitly placed “species preservation” outside those
limits.
To take one example, consider the statute that once
granted the old Federal Power Commission (FPC) the
authority to grant a “certificate of public convenience and
necessity” to permit a natural gas company to operate a
new pipeline. See 15 U. S. C. §717f(c)(1)(A). It says that
“a certificate shall be issued to any qualified applicant
therefor . . . if it is found that the applicant is able and
willing properly to do the acts and to perform the service
proposed . . . and that the proposed service . . . is or will be
required by the present or future public convenience and
necessity.” §717f(e).
Before enactment of the Endangered Species Act of
1973, 87 Stat. 884, it is at least uncertain whether the
FPC could have withheld a certificate simply because a
natural gas pipeline might threaten an endangered ani
mal, for given the Act’s language and history, species
preservation does not naturally fall within its terms. But
we have held that the Endangered Species Act changed
the regulatory landscape, “indicat[ing] beyond doubt that
Congress intended endangered species to be afforded the
highest of priorities.” TVA v. Hill, 437 U. S. 153, 174
(1978) (emphasis added). Indeed, the Endangered Species
Act demonstrated “a conscious decision by Congress to
give endangered species priority over the ‘primary mis
sions’ of federal agencies.” Id., at 185. And given a new
 Cite as: 551 U. S. ____ (2007) 3

BREYER, J., dissenting

pipeline’s potential effect upon habitat and landscape, it
seems reasonable to believe, once Congress enacted the
new law, the FPC’s successor (the Federal Energy Regula
tory Commission) would act within its authority in taking
species-endangering effects into account.
To take another example, the Food and Drug Admini
stration (FDA) has, by statute, an “exclusive” list of crite
ria to consider in reviewing applications for approval of a
new drug. See 21 U. S. C. §355(d) (“If the Secretary finds .
. . [e.g.,] the investigations . . . do not include adequate
tests by all methods reasonably applicable to show
whether or not such drug is safe . . . he shall issue an
order refusing to approve the application”). Preservation
of endangered species is not on this “exclusive” list of
criteria. Yet I imagine that the FDA now should take
account, when it grants or denies drug approval, of the
effect of manufacture and marketing of a new drug upon
the preservation or destruction of an endangered species.
The only meaningful difference between the provision
now before us, §402(b) of the Clean Water Act, and the
energy- and drug-related statutes that I have mentioned is
that the very purpose of the former is to preserve the state
of our natural environment—a purpose that the Endan
gered Species Act shares. That shared purpose shows that
§7(a)(2) must apply to the Clean Water Act a fortiori.