KY Waterways v. Johnson ( 2008 )


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  •                          RECOMMENDED FOR FULL-TEXT PUBLICATION
    Pursuant to Sixth Circuit Rule 206
    File Name: 08a0333p.06
    UNITED STATES COURT OF APPEALS
    FOR THE SIXTH CIRCUIT
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    KENTUCKY WATERWAYS ALLIANCE; SIERRA CLUB
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    CUMBERLAND CHAPTER; KENTUCKIANS FOR THE
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    COMMONWEALTH; FLOYDS FORK ENVIRONMENTAL
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    No. 06-5614
    ASSOCIATION,
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    Plaintiffs-Appellants,        >
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    v.
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    STEPHEN L. JOHNSON, in his official capacity as
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    ADMINISTRATOR OF THE UNITED STATES
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    ENVIRONMENTAL PROTECTION AGENCY,
    Defendant-Appellee, -
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    COMMONWEALTH OF KENTUCKY; KENTUCKY COAL
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    ASSOCIATION; ASSOCIATED INDUSTRIES OF
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    KENTUCKY; KENTUCKY CHAMBER OF COMMERCE;
    KENTUCKY LEAGUE OF CITIES,                           -
    Intervening Defendants-Appellees. -
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    Appeal from the United States District Court
    for the Western District of Kentucky at Bowling Green.
    No. 04-00145—Thomas B. Russell, District Judge.
    Argued: January 30, 2008
    Decided and Filed: September 3, 2008
    Before: SILER, CLAY, and COOK, Circuit Judges.
    _________________
    COUNSEL
    ARGUED: Albert F. Ettinger, ENVIRONMENTAL LAW & POLICY CENTER, Chicago, Illinois,
    for Appellants. Robert J. Lundman, UNITED STATES DEPARTMENT OF JUSTICE, Washington,
    D.C., for Appellees. ON BRIEF: Albert F. Ettinger, ENVIRONMENTAL LAW & POLICY
    CENTER, Chicago, Illinois, Thomas J. FitzGerald, KENTUCKY RESOURCES COUNCIL, INC.,
    Frankfort, Kentucky, for Appellants. Robert J. Lundman, UNITED STATES DEPARTMENT OF
    JUSTICE, Washington, D.C., Sharon R. Vriesenga, Brenda Gail Lowe, KENTUCKY
    ENVIRONMENTAL AND PUBLIC PROTECTION CABINET, Frankfort, Kentucky, Timothy J.
    1
    No. 06-5614                  Kentucky Waterways, et al. v. Johnson, et al.                                         Page 2
    Hagerty, FROST BROWN TODD, LLC, Louisville, Kentucky, Carolyn M. Brown, John C. Bender,
    GREENEBAUM, DOLL & McDONALD, PLLC, Lexington, Kentucky, Mark S. Riddle,
    GREENEBAUM, DOLL & McDONALD, PLLC, Louisville, Kentucky, Culver V. Halliday,
    Kenneth T. Williams, STOLL KEENON OGDEN, PLLC, Louisville, Kentucky, Ronald R. Van
    Stockum, Jr., Louisville, Kentucky, for Appellees. Kevin Reuther, MINNESOTA CENTER FOR
    ENVIRONMENTAL ADVOCACY, St. Paul, Minnesota, Nancy K. Stoner, NATURAL
    RESOURCES DEFENSE COUNCIL, INC., Washington, D.C., Karla Raettig, Michele Merkel,
    ENVIRONMENTAL INTEGRITY PROJECT, Washington, D.C., Scott L. Long, BROWN,
    WINICK, GRAVES, GROSS, BASKERVILLE & SCHOENEBAUM, Des Moines, Iowa, for Amici
    Curiae.
    CLAY, J., delivered the opinion of the court. COOK, J. (pp. 21-24), delivered the remainder
    of the court’s opinion in a separate concurring opinion, in which SILER, J., joined.
    _________________
    OPINION
    _________________
    CLAY, Circuit Judge. Plaintiffs, Kentucky Waterways Alliance, Sierra Club Cumberland
    Chapter, Kentuckians for the Commonwealth, and Floyds Fork Environmental Association, appeal
    the district court’s grant of summary judgment in favor of Defendants, Stephen L. Johnson, in his
    official capacity as Administrator of the United States Environmental Protection Agency (“EPA”),
    the Commonwealth of Kentucky, the Kentucky Coal Association, Associated Industries of
    Kentucky, the Kentucky Chamber of Commerce, and the Kentucky League of Cities, on Plaintiffs’
    challenge, brought pursuant to the Administrative Procedures Act (“APA”), 5 U.S.C. § 701 et seq.
    (2000), of the EPA’s approval, under § 303(c) of the Clean Water Act, 33 U.S.C. § 1313(c) (2000),
    of Kentucky’s regulatory implementation of its Tier II water quality antidegradation rules. For the
    reasons set forth in parts I, II, and III-A of this opinion as well as for the reasons expressed in Judge
    Cook’s concurring opinion, we AFFIRM in part and REVERSE in part the district court’s opinion
    and order, VACATE in part the EPA’s approval of Kentucky’s Tier II antidegradation rules, and
    REMAND the matter to the EPA for further proceedings consistent with these opinions.1
    I. BACKGROUND
    A.       Statutory and Regulatory Framework
    The Federal Water Pollution Control Act, commonly known as the Clean Water Act
    (“CWA”), 33 U.S.C. § 1251 et seq., “is a comprehensive water quality statute designed to ‘restore
    and maintain the chemical, physical, and biological integrity of the Nation’s waters.’” PUD No. 1
    of Jefferson County v. Wash. Dept. of Ecology, 
    511 U.S. 700
    , 704 (1994) (quoting 33 U.S.C.
    § 1251(a)). In passing the CWA,  Congress sought to eliminate “the discharge of pollutants into the
    [nation’s] navigable waters”2 and to attain “an interim goal of water quality which provides for the
    protection and propagation of fish, shellfish, and wildlife.” 33 U.S.C. § 1251(a)(1)-(2).
    1
    Part III-A of this opinion contains the Court’s holding with respect to Plaintiffs’ first argument. The Court’s
    holding with respect to Plaintiff’s second claim is set forth in Judge Cook’s concurring opinion. Part III-B of this opinion
    expresses the views of Judge Clay only.
    2
    The CWA defines “pollutant”as “dredged spoil, solid waste, incinerator residue, sewage, garbage, sewage
    sludge, munitions, chemical wastes, biological materials, radioactive materials, heat, wrecked or discarded equipment,
    rock, sand, cellar dirt and industrial, municipal, and agricultural waste discharged into water.” 33 U.S.C. § 1362(6).
    No. 06-5614                  Kentucky Waterways, et al. v. Johnson, et al.                                        Page 3
    To achieve these goals, the CWA “provides for two sets of water quality measures.”
    Arkansas v. Oklahoma, 
    503 U.S. 91
    , 101 (1992). First, the CWA requires the EPA “to establish and
    enforce technology-based   limitations on individual discharges into the country’s navigable waters
    from point-sources.”3 PUD No. 1 of Jefferson 
    County., 511 U.S. at 704
    (citing 33 U.S.C. §§ 1311,
    1314). These effluent limitations “restrict the quantities, rates, and concentrations of specified
    substances which are discharged from point sources.” Arkansas v. 
    Oklahoma, 503 U.S. at 101
    . In
    order to comply with the CWA, an individual point-source discharger must obtain and adhere to the
    terms of a National Pollutant Discharge Elimination System (“NPDES”) permit issued by the EPA
    or an EPA-authorized state agency. 33 U.S.C. § 1342(a)-(d). The EPA has authorized Kentucky
    to issue NPDES permits for waters within the Commonwealth, see Approval of Kentucky’s NPDES
    Program, 48 Fed. Reg. 45,597 (Oct. 6, 1983), under a program referred to as the Kentucky Pollution
    Discharge Elimination System (“KPDES”). 401 Ky. Admin. Regs. 5:050 (2007).
    Second, § 303 of the CWA “requires each State, subject to federal approval, to institute
    comprehensive water quality standards establishing water quality goals for all intrastate waters.”
    PUD No. 1 of Jefferson 
    County, 511 U.S. at 704
    (citing 33 U.S.C. §§ 1311(b)(1)(C), 1313). The
    statute provides that these water quality standards “shall consist of the designated uses of the
    navigable waters involved and the water quality criteria for such waters based upon such uses. Such
    standards shall be such as to protect the public health or welfare, enhance the quality of water and
    serve the purposes of [the CWA].” 33 U.S.C. § 1313(c)(2)(A). The Supreme Court has further
    explained that “[t]hese state water quality standards provide ‘a supplementary basis . . . so that
    numerous point sources, despite individual compliance with effluent limitations, may be further
    regulated to prevent water quality from falling below acceptable levels.’” PUD No. 1 of Jefferson
    
    County, 511 U.S. at 704
    (quoting EPA v. California ex rel. State Water Resources Control Bd., 
    426 U.S. 200
    , 205 n.12 (1976)).
    Pursuant to a 1987 amendment to the CWA, these state-established water quality standards
    must include an antidegradation policy, which is “a policy requiring that state standards be sufficient
    to maintain existing beneficial uses of navigable waters, preventing their further degradation.” 
    Id. at 705.
    Specifically, the CWA permits the revision of certain effluent limitations or water quality
    standards “only if such revision is subject to and consistent with the antidegradation policy
    established under [the CWA].” 33 U.S.C. § 1313(d)(4)(B). Accordingly, the EPA’s regulations
    implementing the CWA require each State to “develop and adopt a statewide antidegradation policy
    and identify the methods for implementing such policy.” 40 C.F.R. § 131.12(a) (2008).
    The EPA regulations further provide that “[t]he antidegradation policy and implementation
    methods shall, at a minimum, be consistent with” certain federal standards provided for in the
    regulation. 40 C.F.R. § 131.12(a). These federal standards establish three levels of water quality
    protection: Tier I, Tier II, and Tier III.
    Tier I protection establishes the minimum water quality standard for all of a State’s waters
    and requires that “[e]xisting instream water uses and the level of water quality necessary to protect
    the existing uses shall be maintained and protected.” 40 C.F.R. § 131.12(a)(1).
    3
    The CWA defines “point source” as “any discernible, confined and discrete conveyance, including, but not
    limited to any pipe, ditch, channel, tunnel, conduit, well, discrete fissure, container, rolling stock, concentrated animal
    feeding operation, or vessel or other floating craft, from which pollutants are or may be discharged.” 33 U.S.C. §
    1362(14). The CWA does not define non-point source pollution and does not appear to regulate such pollution. See
    Defenders of Wildlife v. EPA, 
    415 F.3d 1121
    , 1124 (10th Cir. 2005); American Wildlands v. Browner, 
    260 F.3d 1192
    ,
    1193-1194 (10th Cir. 2001). One court has described non-point source pollution as “nothing more than a pollution
    problem not involving a discharge from a point source.” Nat’l Wildlife Fed’n v. Gorsuch, 
    693 F.2d 156
    , 166 n.28 (D.C.
    Cir. 1982).
    No. 06-5614                  Kentucky Waterways, et al. v. Johnson, et al.                                      Page 4
    Tier II protection applies when “the quality of the waters exceed levels necessary to support
    propagation of fish, shellfish, and wildlife and recreation in and on the water.” 40 C.F.R.
    § 131.12(a)(2). For such waters, the regulation requires that their “quality shall be maintained and
    protected unless the State finds, after full satisfaction of the intergovernmental coordination and
    public participation provisions of the State’s continuing planning process, that allowing lower water
    quality is necessary to accommodate important economic and social development in the area in
    which the waters are located.” 40 C.F.R. § 131.12(a)(2). However, “[i]n allowing such degradation4
    or lower water quality, the State shall assure water quality adequate to protect existing uses fully.”
    40 C.F.R. § 131.12(a)(2).
    Finally, Tier III protection provides that “[w]here high quality waters constitute an
    outstanding National resource, such as waters of National and State parks and wildlife refuges and
    waters of exceptional recreational or ecological significance, that water quality shall be maintained
    and protected.” 40 C.F.R. § 131.12(a)(3).
    Once a State adopts or revises its water quality standards, including its antidegradation
    policy, the CWA requires the State to submit these standards to the EPA for review. 33 U.S.C.
    § 1313(c)(1). If the State’s standards and implementation procedures are consistent with the
    minimum federal standards required by the CWA and the EPA’s implementing regulations, then the
    EPA must approve the state standards within sixty days. 33 U.S.C. § 1313(c)(3). However, if the
    state water quality standards do not satisfy the CWA’s requirements, the EPA must, within ninety
    days, “notify the State and specify the changes to meet such requirements. If such changes are not
    adopted by the State within ninety days after the date of notification, the [EPA] shall promulgate
    such standard[s].” 33 U.S.C. § 1313(c)(3).
    B.       Factual and Procedural History
    Kentucky adopted its original antidegradation policy in 1979.5 In 1995, the Kentucky
    Environmental and Public Protection Cabinet (the “Cabinet”) established  implementation procedures
    for this policy by adopting 401 Ky. Admin. Regs. 5:030.6 On August 11, 1995, the Cabinet
    submitted these antidegradation implementation procedures to the EPA for approval. Two years
    later, on August 7, 1997, the EPA disapproved a portion of Kentucky’s antidegradation program
    because it found that the selection criteria for water bodies that would be given Tier II protection
    were not sufficiently inclusive and, therefore, did not meet the requirements of 40 C.F.R. § 131.12.
    On December 8, 1999, in response to this disapproval, Kentucky adopted revisions to its
    water quality standards, including revisions to 401 Ky. Admin. Regs. 5:030. The Cabinet submitted
    4
    This Tier II standard may also be described as protecting the water body’s “assimilative capacity” which is
    the amount by which the water body exceeds the quality level necessary to support its designated uses. Under the
    regulation, a pollution increase that would decrease a water body’s assimilative capacity would need to be justified by
    the necessity of the pollution for achieving important economic and social development. However, the regulation
    prohibits any pollution increase that would create negative assimilative capacity, regardless of the economic or social
    necessity for the pollution.
    5
    Kentucky’s antidegradation policy, which provides for the type of protection afforded to various qualitative
    categories of water bodies, is found in 401 Ky. Admin. Regs. 5:029.
    6
    While Kentucky’s general antidegradation policy is contained in 401 Ky. Admin. Regs. 5:029, the
    implementation procedures specifying which particular water bodies fall within each protection category are contained
    in 401 Ky. Admin. Regs. 5:030. Thus, Plaintiffs’ challenge regarding the EPA’s approval of the Cabinet’s revision of
    401 Ky. Admin. Regs. 5:030 is not technically a challenge to Kentucky’s antidegradation policy, but rather is a challenge
    to Kentucky’s implementation of this policy through its selection of which waters merit Tier II protection and its
    categorical exclusion of certain types of discharges from Tier II review.
    No. 06-5614             Kentucky Waterways, et al. v. Johnson, et al.                           Page 5
    these revisions to the EPA for approval on December 15, 1999. On August 30, 2000, the EPA
    notified the Cabinet that these revised Tier II rules failed to fully address the concerns identified in
    the EPA’s 1997 disapproval.
    On May 19, 2001, Plaintiffs served notice of their intent to commence a civil action under
    the citizen suit provision of the CWA, 33 U.S.C. § 1365, for the alleged failure of the EPA
    Administrator to perform his mandatory duty under 33 U.S.C. § 1313(c)(4) to promulgate a federal
    standard implementing antidegradation requirements for Kentucky. In November 2002, the EPA
    proposed a federal antidegradation implementation procedure for Kentucky to adopt. Plaintiffs,
    however, advised the EPA that the proposal was inadequate to ensure compliance with the CWA.
    On February 17, 2004, Plaintiffs renewed their 60-day notice, demanding that the EPA
    perform its duty to finalize Tier II antidegradation rules for Kentucky that comply with the CWA.
    On September 8, 2004, the Cabinet adopted a revised version of its antidegradation implementation
    procedure regulation, 401 Ky. Admin. Reg. 5:030, and submitted it to the EPA for approval on
    September 23, 2004. However, two days prior to this submission, on September 21, 2004, Plaintiffs
    commenced the instant action against the EPA in the United States District Court for the Western
    District of Kentucky. Plaintiffs’ initial two-count complaint alleged that: (1) the EPA had failed to
    comply with its mandatory duty under the CWA to finalize federal water quality Tier II
    antidegradation standards for Kentucky; and (2) this failure to comply with a mandatory CWA duty
    was arbitrary, capricious, and contrary to law, in violation of the APA.
    On January 29, 2005, Plaintiffs filed a motion for summary judgment requesting that the
    district court order the EPA to promulgate antidegradation regulations for Kentucky. However, on
    April 12, 2005, prior to the district court’s issuance of a ruling on Plaintiffs’ summary judgment
    motion, the EPA approved Kentucky’s revised antidegradation implementation procedures, based
    on its extensive evaluation of those procedures. See J.A. at 176-233 (EPA Determination Under
    Section 303(c) of the Clean Water Act, Review of Regulation 401 KAR 5:030, Kentucky
    Antidegradation Policy Implementation Methodology (Apr. 12, 2005) (hereinafter “EPA Approval
    Document”)).
    In response to this development, Plaintiffs amended their complaint on May 27, 2005 to
    include a third count—that the EPA’s approval of Kentucky’s revised antidegradation
    implementation procedures was arbitrary, capricious, and otherwise contrary to law. On June 6,
    2005, Plaintiffs moved to dismiss counts I and II of their amended complaint. Thereafter, the
    Commonwealth of Kentucky, the Kentucky Coal Association, Associated Industries of Kentucky,
    the Kentucky Chamber of Commerce, and the Kentucky League of Cities intervened as defendants.
    On June 13, 2005, the district court approved Plaintiffs’ voluntary dismissal of counts I and II of the
    amended complaint, leaving only Plaintiffs’ count III claim that the EPA acted arbitrarily and
    capriciously in approving Kentucky’s revised antidegradation implementation procedures.
    On September 6, 2005, Plaintiffs filed a motion for summary judgment on count III of their
    amended complaint. Defendants responded by filing a cross-motion for summary judgment on
    October 31, 2005. On March 31, 2006, the district court issued an opinion and order denying
    Plaintiffs’ motion for summary judgment and granting Defendants’ motion for summary judgment.
    See Kentucky Waterways Alliance v. Johnson, 
    426 F. Supp. 2d 612
    , 616 (W.D. Ky. 2006). This
    timely appeal followed.
    No. 06-5614              Kentucky Waterways, et al. v. Johnson, et al.                            Page 6
    II. STANDARD OF REVIEW
    A.      Review Under the APA
    When a district court upholds on summary judgment an administrative agency’s final
    decision under the APA, we review the district court’s summary judgment decision de novo, while
    reviewing the agency’s decision under the APA’s arbitrary and capricious standard. City of
    Cleveland v. Ohio, 
    508 F.3d 827
    , 838 (6th Cir. 2007) (quoting Coalition for Gov’t Procurement v.
    Fed. Prison Indus., Inc., 
    365 F.3d 435
    , 457 (6th Cir. 2004)). The APA directs that when reviewing
    the decision of an administrative agency, a court shall “hold unlawful and set aside the agency
    action” if the action is “arbitrary, capricious, an abuse of discretion or otherwise not in accordance
    with law.” 5 U.S.C. § 706(2)(A). “A court reviewing an agency’s adjudicative action should accept
    the agency’s factual findings if those findings are supported by substantial evidence on the record
    as a whole.” Arkansas v. 
    Oklahoma, 503 U.S. at 113
    (emphasis altered).
    Under this APA standard, the reviewing court “must consider whether the decision was
    based on a consideration of the relevant factors and whether there has been a clear error of
    judgment.” Marsh v. Oregon Natural Res. Council, 
    490 U.S. 360
    , 378 (1989) (quoting Citizens to
    Preserve Overton Park, Inc. v. Volpe, 
    401 U.S. 402
    , 416 (1971)). An agency decision is “arbitrary
    and capricious” when the agency:
    has relied on factors which Congress had not intended it to consider, entirely failed
    to consider an important aspect of the problem, offered an explanation 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.
    Nat’l Ass’n of Home Builders v. Defenders of Wildlife, 
    127 S. Ct. 2518
    , 2529 (2007) (quoting Motor
    Vehicle Mfrs. Ass’n of United States, Inc. v. State Farm Mut. Auto. Ins. Co., 
    463 U.S. 29
    , 43 (1983)).
    The reviewing court “may not supply a reasoned basis for the agency’s action that the agency itself
    has not given.” Motor Vehicle Mfrs. 
    Ass’n, 463 U.S. at 43
    . However, “[e]ven when an agency
    explains its decision with less than ideal clarity, a reviewing court will not upset the decision on that
    account if the agency’s path may be reasonably discerned.” Alaska Dep’t of Env’t Conservation v.
    EPA, 
    540 U.S. 461
    , 497 (2004).
    The Supreme Court has explained that “[r]eview under the arbitrary and capricious standard
    is deferential.” Nat’l Ass’n of Home 
    Builders, 127 S. Ct. at 2529
    . “Nevertheless, merely because
    our review must be deferential does not mean that [it] must also be inconsequential.” Moon v. Unum
    Provident Corp., 
    405 F.3d 373
    , 379 (6th Cir. 2005). “The arbitrary-and-capricious standard . . . does
    not require us merely to rubber stamp the [agency’s] decision.” Jones v. Metropolitan Life Ins. Co.,
    
    385 F.3d 654
    , 661 (6th Cir. 2004). Indeed, “[d]eferential review is not no review, and deference
    need not be abject.” McDonald v. Western-Southern Life Ins. Co., 
    347 F.3d 161
    , 172 (6th Cir.
    2003).
    B.      Deference to Agency Interpretation of Statutes and Regulations
    In reviewing a federal agency’s interpretation of a statute that it administers, a reviewing
    court must first ask “whether Congress has directly spoken to the precise question at issue.”
    Chevron U.S.A., Inc. v. Natural Res. Def. Council, Inc., 
    467 U.S. 837
    , 842 (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.” 
    Id. at 842-43.
    However, if “Congress has not
    directly addressed the precise question at issue” and “the statute is silent or ambiguous with respect
    to the specific issue,” then “the question for the court is whether the agency’s answer is based on
    a permissible construction of the statute.” 
    Id. at 843.
    If the agency’s construction is a permissible
    one, even if it is not “the reading the court would have reached if the question initially had arisen
    No. 06-5614             Kentucky Waterways, et al. v. Johnson, et al.                           Page 7
    in a judicial proceeding,” then the court must defer to the agency’s interpretation. 
    Id. at 843
    n.11.
    “In such a case, a court may not substitute its own construction of a statutory provision for a
    reasonable interpretation made by the administrator of an agency.” 
    Id. at 843.
             When interpreting an agency regulation, a court should also defer to the agency’s
    interpretation of the regulation unless it is plainly erroneous or inconsistent with the regulation.
    Auer v. Robbins, 
    519 U.S. 452
    , 461 (1997). However, “deference is warranted only when the
    language of the regulation is ambiguous.” Christensen v. Harris County, 
    529 U.S. 576
    , 588 (2000).
    If the language of the regulation is clear, then “[t]o defer to the agency’s position would be to permit
    the agency, under the guise of interpreting a regulation, to create a de facto new regulation.” 
    Id. III. DISCUSSION
            On appeal, Plaintiffs raise two challenges to the EPA’s approval of Kentucky’s
    antidegradation implementation regulation, 401 Ky. Admin. Regs. 5:030. First, Plaintiffs contend
    that the EPA’s approval of Kentucky’s classification of certain waters as eligible for Tier I
    protection rather than Tier II protection was arbitrary, capricious, and contrary to law. Second,
    Plaintiffs argue that the EPA’s approval of Kentucky’s categorical exemption of six types of
    pollution discharges from the Tier II review procedure was arbitrary, capricious, and contrary to law.
    We consider each of these challenges in turn.
    A.      EPA’s Approval of Kentucky’s Selection of Waters for Tier II Protection
    Plaintiffs first challenge concerns the EPA’s approval of the way in which Kentucky
    designates waters for Tier II protection. Kentucky’s antidegradation implementation procedures
    divide Kentucky’s water bodies into four categories: (1) outstanding national resource water
    (“ONRW”); (2) exceptional water; (3) high quality water; and (4) impaired water. See 401 Ky.
    Admin. Regs. 5:030. ONRWs, which consist of about 30 miles of two streams and all of the
    underground rivers in Mammoth Cave National Park, are afforded Tier III protection. See 401 Ky.
    Admin. Regs. 5:030 § 1(1)(a)-(b). Exceptional water, which consists of water bodies satisfying the
    criteria set forth in 401 Ky. Admin. Regs. 5:030 § 1(2)(a), receives Tier II protection. See 401 Ky.
    Admin. Regs. 5:030 § 1(2)(b). High quality water, which is defined as all water that is not
    designated as ONRW, exceptional water, or impaired water, is also afforded Tier II protection. See
    401 Ky. Admin. Regs. 5:030 § 1(3)(a)-(b). Finally, impaired water, which consists of those water
    bodies for which one or more designated uses are listed as impaired by Kentucky in its biennial
    report required under 33 U.S.C. § 1315, is afforded Tier I protection. See 401 Ky. Admin. Regs.
    5:030 § 1(4)(a)-(b).
    Plaintiffs contend that the EPA’s approval of Kentucky’s exclusion of impaired waters from
    Tier II protection was arbitrary and capricious for three reasons. First, Plaintiffs maintain that
    Kentucky’s use of a water body-by-water body approach instead of a parameter-by-parameter
    approach for determining which waters merit Tier II protection was inconsistent with the goals of
    the CWA and the language of 40 C.F.R. § 131.12(a)(2). Second, Plaintiffs claim that, even if the
    regulations permitted Kentucky to use a water body-by-water body approach, Kentucky’s
    categorical exclusion of waters listed as “impaired” under 33 U.S.C. § 1315 is arbitrary and
    unsupported by the evidence in the record. Third, and finally, Plaintiffs argue that exclusion of
    impaired water from Tier II protection results in the exclusion of a substantial number of Kentucky’s
    water bodies from Tier II protection. We find none of these arguments to have merit.
    No. 06-5614                 Kentucky Waterways, et al. v. Johnson, et al.                                     Page 8
    1.       Water Body-by-Water Body Approach vs. Parameter-by-
    Parameter Approach
    Plaintiffs first contend that the EPA contradicted the CWA by approving Kentucky’s water
    body-by-water body approach to antidegradation policy implementation because both the CWA and
    40 C.F.R. § 131.12(a)(2) require States to adopt a parameter-by-parameter approach in designating
    which waters receive Tier II protection. The district court rejected a similar argument, see Kentucky
    
    Waterways, 426 F. Supp. 2d at 631-33
    , and we likewise find the argument unpersuasive.
    The EPA’s CWA-implementing regulations require States to ensure that waters whose
    quality “exceed[s] levels necessary to support propagation of fish, shellfish, and wildlife and
    recreation in and on the water” receive Tier II protection, i.e., their existing high water quality must
    be maintained and protected unless it is demonstrated that a lowering of water quality is necessary
    to accommodate important economic or social development. 40 C.F.R. § 131.12(a)(2). However,
    as the EPA itself has publicly noted in its advance notice of proposed rule-making, “the regulation
    does not include specific guidelines for identifying [these] high quality waters.” Water Quality
    Standards Regulation,   63 Fed. Reg. 36,742, 36,782 (proposed July 7, 1998) (to be codified at 40
    C.F.R. pt. 131).7 Instead, “States and Tribes have developed various ways to identify their [T]ier
    [II] waters.” 
    Id. These “approaches
    for identifying high quality waters fall into two basic categories:
    (1) pollutant-by-pollutant approaches, and (2) water body-by-water body approaches.” 
    Id. Under the
    pollutant-by-pollutant approach (which is the same as Plaintiffs’ parameter-by-parameter
    approach), “the State makes a classification for each pollutant in a given water body.” Ohio Valley
    Environmental Coalition v. Horinko, 
    279 F. Supp. 2d 732
    , 747 (S.D. W.Va. 2003). The water body
    is then given Tier II protection against those pollutants for which “water quality is better than
    applicable criteria.” Water Quality Standards Regulation, 63 Fed. Reg. at 36,782. “[A]vailable
    assimilative capacity for any given pollutant is always subject to [Tier II] protection, regardless of
    whether the criteria for other pollutants are satisfied.” 
    Id. Thus, under
    this approach, the same water
    body could be classified as Tier II for certain pollutants and Tier I for other pollutants. See Ohio
    
    Valley, 279 F. Supp. 2d at 747
    .
    Under the water body-by-water body approach (also know as the designational approach),
    States “weigh a variety of factors to judge a water body segment’s overall quality.” Water Quality
    Standards Regulation, 63 Fed. Reg. at 36,782. Tier II classification is then “based on the overall
    quality of the water body segment, not on individual pollutants.” Ohio 
    Valley, 279 F. Supp. 2d at 747
    . “Under this approach, assimilative capacity for a given pollutant may not be subject to [Tier
    II] protection if, overall, the segment is not deemed ‘high quality.’” Water Quality Standards
    Regulation, 63 Fed. Reg. at 36,782.
    The EPA has not found either of these approaches to be compelled by the language of 40
    C.F.R. § 131.12(a)(2) or the CWA. See 
    id. On the
    contrary, the EPA has found that “[t]here are
    advantages and disadvantages to each approach.” 
    Id. The pollutant-by-pollutant
    approach is easier
    to implement for some States “because the need for an overall assessment considering various
    factors is avoided.” 
    Id. This approach
    might also have the benefit of generally including more
    waters within Tier II protection “because it would cover waters that are clearly not attaining goal
    uses (i.e., waters which are not supporting ‘fishable/swimmable’ goal uses but that possess
    assimilative capacity for one or more pollutant [sic]).” 
    Id. at 36,782-36,783.
    “The water body-by-
    water body approach, on the other hand, allows for a weighted assessment of chemical, physical,
    7
    As noted previously, an administrative agency’s interpretation of its own regulation is entitled to great
    deference, see 
    Auer, 519 U.S. at 461
    (1997), and thus provides useful guidance to this Court in assessing the merits of
    Plaintiffs’ argument in this case.
    No. 06-5614              Kentucky Waterways, et al. v. Johnson, et al.                            Page 9
    biological, and other information (e.g., unique ecological or scientific attributes).” 
    Id. at 36,
    783.
    By allowing the high quality water decision to be made in advance of the antidegradation review,
    this approach may facilitate implementation. 
    Id. The approach
    “also allows States and Tribes to
    focus limited resources on protecting higher-value State or Tribal waters.” 
    Id. Accordingly, the
    EPA has concluded that “neither approach is clearly superior and that either, when properly
    implemented, is acceptable.” 
    Id. at 36,
    782.
    Likewise, the United States District Court for the Southern District of West Virginia, the
    only court which has previously considered this issue, has also concluded that the federal statute and
    regulations do not require States to choose the pollutant-by-pollutant approach over the water body-
    by-water body approach. See Ohio 
    Valley, 279 F. Supp. 2d at 747
    . On the contrary, in Ohio Valley
    Environmental Coalition v. Horinko, that court found that “the EPA’s regulations permit a State to
    adopt a water body-by-water body approach to classification, assuming that this approach is
    implemented adequately.” 
    Id. Plaintiffs nevertheless
    contend that the language of 40 C.F.R. § 131.12(a) requires a
    pollutant-by-pollutant approach. They emphasize “the fact that the regulation speaks of protecting
    levels of quality rather than protecting ‘high quality waters.’” Pl. Br. at 23. They argue that,
    because the regulation protects the quality of waters when that quality “exceeds levels necessary to
    support” fish and recreation, a water body with safe levels of one or more pollutant must be
    protected from unnecessary new loadings of that pollutant, even if the water body is suffering from
    excess loadings of a different pollutant. 
    Id. at 21
    (quoting 40 C.F.R. § 131.12(a)(2)). Thus, they
    conclude that the regulation requires Tier II protection be determined according to a pollutant-by-
    pollutant approach.
    We find Plaintiffs’ argument to demonstrate only that a pollutant-by-pollutant approach is
    consistent with the regulation, not that it is required by the regulation. Plaintiffs’ focus on the plural
    “levels” ignores the rest of the phrase in which that word appears. The regulation requires
    protection of water quality when “the quality of the waters exceed levels necessary to support the
    propagation of fish, shellfish, and wildlife and recreation in and on the water.” 40 C.F.R.
    § 131.12(a)(2). This language is susceptible to two interpretations. The first is that offered by
    Plaintiffs, i.e., that “levels” refers to the levels of various pollutants in the water body. However,
    the word “levels” here could also refer to the overall quality levels necessary to support the various
    water uses mentioned in the regulation. For any particular water body there could be one quality
    level necessary to support the propagation of fish, a different quality level necessary to support the
    propagation of wildlife, and finally a third quality level necessary to support recreation. Either
    reading seems consistent with the plain language of the regulation and neither reading seems
    compelled by the language. Given this ambiguity in the regulation, we defer to the EPA’s
    interpretation, see 
    Auer, 519 U.S. at 461
    , which holds that either approach is permissible. Thus, we
    do not find the EPA’s approval of Kentucky’s use of a water body-by-water body approach to be
    arbitrary, capricious, or contrary to law.
    2.      Evidence Supporting the Categorical Exclusion of “Impaired
    Waters” From Tier II Protection
    Plaintiffs next argue that, even if Kentucky’s use of a water body-by-water body approach
    in classifying waters for Tier II protection is permissible, “the Kentucky rules cannot be upheld
    because the method for selecting waters to be left unprotected is arbitrary and without support in the
    record.” Pl. Br. at 24. Relying on Ohio Valley, Plaintiffs claim that merely listing a water body as
    “impaired” is insufficient to justify denial of Tier II protection. They maintain that “[t]he fact that
    a water body fails to meet one or more water quality criteria is not determinative of the overall
    quality of its water or whether existing ‘quality of the waters exceed[s] levels necessary to support
    propagation of fish shellfish, and wildlife and recreation in and on the water.’” 
    Id. at 26
    (quoting
    No. 06-5614                  Kentucky Waterways, et al. v. Johnson, et al.                                     Page 10
    40 C.F.R. § 131.12(a)(2)). Instead of focusing on whether the water is impaired, Plaintiffs argue,
    Kentucky “must look at a full range of ‘qualification criteria’ to determine if a water body is of
    sufficient quality for Tier II protection.” 
    Id. at 25.
    Because the Kentucky implementation
    procedures fail to classify Tier II waters on this basis, Plaintiffs contend that the EPA erred in
    approving them.
    Defendants counter that exclusion of Tier II protection from impaired waters is consistent
    with 40 C.F.R. § 131.12(a)(2). They argue that, because the regulation requires Tier II protection
    only for waters whose quality supports both aquatic life-based uses and recreation-based uses,
    Kentucky may reasonably     exclude bodies of water from Tier II protection if the water is impaired
    for any of those uses.8 We agree with Defendants that Kentucky’s exclusion of “impaired” waters
    from Tier II protection is consistent with the requirements of 40 C.F.R. § 131.12(a).
    Kentucky’s antidegradation implementation procedures provide Tier II protection to the
    State’s “exceptional waters” and its “high quality waters.” 401 Ky. Admin. Regs. 5:030 §§ 1(2)(b)
    and (3)(b). In contrast, Kentucky extends only Tier I protection to “surface water categorized as
    impaired for applicable designated uses” unless “the surface water is listed as an outstanding state
    resource water in 401 KAR 5:026.” 401 Ky. Admin. Regs. 5:030 § 1(4)(a). The Kentucky
    regulation clarifies that “a surface water categorized as impaired for applicable designated uses shall
    be a water identified pursuant to 33 U.S.C. § 1315.” 
    Id. Section 1315
    (§ 305 of the CWA),
    however, does not provide a definition of impaired water. Rather, § 1315 requires each State to
    submit a biennial report to the EPA (“§ 305 report”) which includes, inter alia:
    (A) a description of the water quality of all navigable waters in [the] State during the
    preceding year . . . (B) an analysis of the extent to which all navigable waters of [the]
    State provide for the protection and propagation of a balanced population of
    shellfish, fish, and wildlife, and allow recreational activities in and on the water;
    [and] (C) an analysis of the extent to which the elimination of the discharge of
    pollutants and a level of water quality which provides for the protection and
    propagation of a balanced population of shellfish, fish, and wildlife and allows
    recreational activities in and on the water, have been or will be achieved by the
    requirements of [the CWA], together with recommendations as to additional action
    necessary to achieve such objectives and for what waters such additional action is
    necessary.
    33 U.S.C. § 1315(b)(1). Section 1315 does not require this report to include an identification of
    impaired waters. Instead, the requirement to identify impaired waters in this § 305 report seems to
    come from 33 U.S.C. § 1313(d)(1) (§ 303(d) of the CWA) which requires each State to “identify
    those waters within its boundaries for which the effluent limitations required by [the CWA] are not
    8
    Defendant Commonwealth of Kentucky further argues that excluding impaired waters from Tier II protection
    is consistent with 33 U.S.C. § 1313(d)(4)(B). The Commonwealth interprets this provision of the CWA as requiring
    States to apply antidegradation review only to waters whose applicable water quality standard has been attained. As
    impaired waters, by definition, have not attained their applicable water quality standard, the Commonwealth argues that
    it is appropriate not to afford them Tier II antidegradation protection.
    We find the Commonwealth’s statutory argument to be misguided. A careful reading of 33 U.S.C. § 1313(d)
    reveals that the section has nothing to do with identifying which water bodies should receive Tier II protection. Rather,
    this section sets out the conditions that must be satisfied prior to modifying NPDES permits to include less stringent
    effluent limitations. See 33 U.S.C. § 1313(d). Section 1313(d)(4)(b) provides that, for water bodies whose quality
    “equals or exceeds levels necessary to protect [their] designated uses,” any revisions to the effluent limitations placed
    on that water body must be “consistent with the antidegradation policy established under this section.” The section does
    not address the question of how States must determine which waters receive Tier II antidegradation protection and is thus
    not helpful in resolving the parties’ dispute on this point.
    No. 06-5614              Kentucky Waterways, et al. v. Johnson, et al.                          Page 11
    stringent enough to implement any water quality standard applicable to such waters.” 33 U.S.C.
    § 1313(d)(1)(A). Kentucky submits its § 303(d) list of such impaired waters as part of its annual
    § 305 report. See, e.g., J.A. at 788 (2004 Kentucky Report to Congress on Water Quality). This list
    of impaired waters includes “all waters not supporting one or more designated uses.” Final 2006
    Integrated Report to Congress on the Condition of Water Resources in Kentucky, Volume II, p.1
    (April 4, 2007). Thus, the Kentucky antidegradation implementation regulation clarifies that
    “[s]urface water categorized as impaired shall be assessed by the [C]abinet as not fully supporting
    any applicable designated uses.” 401 Ky. Admin. Regs. 5:030 § 1(4)(a).
    The EPA approved Kentucky’s exclusion of impaired waters from Tier II protection, finding
    it to be “consistent with the federal requirement that high quality waters have water quality that
    supports both aquatic life-based uses and recreation-based uses.” J.A. at 184 (EPA Approval
    Document). In approving Kentucky’s classification of Tier II waters, the EPA noted that, as
    Plaintiffs have argued, Kentucky did not implement a strict water body-by-water body approach:
    Kentucky’s combined selection criteria for classification of waters for
    antidegradation purposes combines some elements of the designational approach and
    some elements of the pollutant-by-pollutant approach. Qualification for the
    exceptional waters category [which receive Tier II protection] is based on meeting
    certain criteria, which include high levels of biological diversity, recognition of
    outstanding values through other statutory provisions, exceptional aesthetic or
    ecological values, historical significance, or high levels of water quality. This is
    typically considered a designational approach.
    However, in adopting the category high quality waters [which are also
    afforded Tier II protection], Kentucky has chosen to create a “default” category that
    contains all other waters of the Commonwealth, unless the water is an ONRW or has
    been show to be impaired for a designated use. This approach is clearly not a
    “designational” approach, since no data are required for a water to be placed in the
    high quality waters category, and Kentucky does not maintain a listing of high
    quality waters that have been classified in that category.
    Qualification for the impaired waters category (i.e., the only waters of the
    Commonwealth that are not considered for [Tier II] protection, at a minimum) is
    based solely on a determination by Kentucky that a water body does not meet the 40
    C.F.R. § 131.12(a)(2) requirement for waters that “exceed levels necessary to support
    propagation of fish, shellfish, and wildlife and recreation in and on the water.”
    (emphasis added). This method of exclusion of waters from consideration as [Tier
    II] waters combines some concepts of both approaches, in that chemical and
    biological data are evaluated in making an impairment decision, but the final
    decision to include waters in this category is based on whether each designated use
    for the water body is being attained.
    J.A. at 185-86 (EPA Approval Document) (emphasis in original). The EPA found that Kentucky’s
    use of this hybrid approach for classifying Tier II waters is consistent with 40 C.F.R. § 131.12(a)(2).
    The EPA also noted that “Kentucky’s categorization approach is similar to the approach approved
    by EPA Region 4 in Alabama and Tennessee.” J.A. at 186 (EPA Approval Document).
    Plaintiffs nevertheless contend that merely listing a water as “impaired” for its designated
    uses is insufficient to justify denial of Tier II protection. Plaintiffs rely on Ohio Valley for support.
    This reliance, however, is misplaced. In Ohio Valley, the issue faced by the court was whether there
    was sufficient evidence in the record to permit the EPA’s approval of West Virginia’s exclusion of
    Tier II protection from particular segments of the Monongahela and Kanawha rivers. 
    279 F. Supp. 2d
    at 746. The court found the that the administrative record was insufficient to support the EPA’s
    decision because the only evidence pertaining to the water quality of those river segments was “the
    No. 06-5614             Kentucky Waterways, et al. v. Johnson, et al.                          Page 12
    fact that both river segments [were] on a list of impaired waters prepared by the WVDEP for
    submission to the EPA under section 303(d) of the Clean Water Act.” 
    Id. at 748.
    The court noted
    that other waters on that list had been classified as Tier II and that the EPA had provided no
    justification for why the particular impairments to Monongahela and Kanawha river segments
    rendered those rivers Tier I “as opposed to other listed waters with similar impairments.” 
    Id. at 749.
    In other words, the problem that the court found with the EPA’s evidence was not that it classified
    the rivers as Tier I based upon their impairment, but rather that the EPA did not have any evidence
    to justify treating some impaired waters as Tier I while classifying others as Tier II. Accordingly,
    Ohio Valley cannot properly be read to stand for the proposition that a water’s impairment is not
    enough to exclude it from Tier II protection when all impaired waters are treated the same for
    antidegradation purposes.
    Perhaps recognizing the flimsy support provided by Ohio Valley, Plaintiffs alternatively
    argue that excluding impaired waters from Tier II protection is arbitrary because, under such an
    approach, a water body’s exclusion from Tier II protection is determined by the designated uses of
    the water rather than by the water’s overall quality. However, this argument overlooks the fact that
    40 C.F.R. § 131.12(a)(2) links a water body’s relevant quality level to its designated uses. Under
    this regulation, Kentucky’s implementation procedures must provide Tier II protection to all of
    Kentucky’s waters whose quality “exceed levels necessary to support propagation of fish, shellfish,
    and wildlife and recreation in and on the water.” 40 C.F.R. § 131.12(a)(2) (emphasis added). In
    other words, Kentucky must provide Tier II protection to waters whose quality is better than the
    minimum level of quality needed to support aquatic-life based uses, wildlife uses, and recreational
    uses. Impaired waters, which, by definition do not have the quality needed to support their uses and
    must “be assessed by the [C]abinet as not fully supporting any designated uses,” 401 Ky. Admin.
    Regs. 5:030 § 1(4)(a) (emphasis added), do not fall within this category of Tier II waters. Impaired
    waters do not even have the minimum quality level that is necessary to support their designated uses,
    let alone a quality that is better than necessary to support aquatic-life based uses, wildlife uses, and
    recreational uses. Plaintiffs have failed to convincingly explain how the exclusion of such waters
    from Tier II protection is problematic under 40 C.F.R. § 131.12(a)(2). Accordingly, we are not
    persuaded that the EPA’s approval of Kentucky’s exclusion of impaired waters from Tier II
    protection was arbitrary, capricious, or contrary to law.
    3.     Percentage of Kentucky Water Bodies Receiving Tier II
    Protection
    Finally, Plaintiffs argue that the district court’s decision should be reversed because it is
    “based on the misunderstanding that the approach [the] EPA approved provided for 90% of
    Kentucky’s waters with Tier II protection.” Pl. Br. at 27. Plaintiffs contend that “the record only
    shows that 90% of the stream miles that had been studied as of the time of the decision were not
    listed as impaired” and that “the 90% stream mile figure does not address the extent to which lakes
    would be protected.” 
    Id. at 28.
    Plaintiffs maintain that “[a]s Kentucky continues to collect data, the
    percentage of waters found to be impaired is likely to be much higher.” 
    Id. We find
    this final argument to be misguided. While Plaintiffs’ criticisms of the district
    court’s calculation of the percentage of Kentucky waters afforded Tier II protection may be well-
    founded—the record only indicates that 90% of the stream miles that had been studied at the time
    of the EPA’s decision are afforded Tier II protection, see J.A. at 187 (EPA Approval
    Document)—Plaintiffs fail to explain how the district court’s factual mischaracterization of the
    record is relevant to our de novo evaluation of whether the EPA’s approval of Kentucky’s
    antidegradation regulations was arbitrary, capricious, or contrary to law. Kentucky’s criteria for
    identifying waters afforded Tier II protection are not to be evaluated based on the percentage of
    waters for which they provide Tier II protection, but rather upon their consistency with 40 C.F.R.
    § 131.12(a)(2). Neither the CWA nor its implementing regulations specify that a certain percentage
    No. 06-5614                  Kentucky Waterways, et al. v. Johnson, et al.                                      Page 13
    of a State’s waters must be afforded Tier II protection. As long as all waters whose quality
    “exceed[s] levels necessary to support propagation of fish, shellfish, and wildlife and recreation in
    and on the water” are granted Tier II protection, the regulation is satisfied. 40 C.F.R. § 131.12(a)(2).
    Plaintiffs’ contention that less than 90% of Kentucky’s waters are afforded Tier II protection does
    not, by itself, demonstrate that the EPA’s approval of Kentucky’s antidegradation implementation
    procedures was arbitrary, capricious, or contrary to law.
    For the foregoing reasons, we AFFIRM the district court’s grant of summary judgment to
    Defendants with respect to the EPA’s approval of Kentucky’s method of selecting which waters merit
    Tier II protection.
    B.      EPA’s Approval of Kentucky’s Multiple Exceptions to Tier II Review9
    Plaintiffs’ second challenge concerns the EPA’s approval of specific exemptions to the Tier
    II review procedure which applies to new discharges into Tier II waters. While Kentucky’s
    antidegradation implementation regulation generally affords Tier II protection to “exceptional water”
    and “high quality water,” the regulation exempts pollution discharges resulting from specific
    categories of activity from Tier II review and allows dischargers in other categories of activity to
    avoid Tier II review by accepting specified permit effluent limitations. In particular, the regulation
    provides categorical exemptions from the Tier II review process specified in 401     Ky. Admin. Regs.
    5:029 for: (1) discharges issued pursuant to storm water general permits;10 (2) coal mining
    discharges; (3) domestic sewage discharges      from single-family residences; (4) concentrated animal
    feeding operation (“CAFO”) discharges;11 and (5) discharges pursuant to KPDES permit renewals
    and modifications that result in less than a twenty percent increase in pollutant loading. See 401 Ky.
    Admin. Regs. 5:030 §§ 1(2)(b)(1)(a)-(e), (3)(b)(1)(a)-(e). The regulation also allows non-domestic
    dischargers (e.g., factories) to opt out of Tier II review for new KPDES permits if they accept permit
    limits that are “restricted to no more than one-half (1/2) of the water quality based limitations that
    would have been permitted at standard design conditions.” 401 Ky. Admin. Regs. 5:030
    9
    This portion of the opinion expresses only the views of Judge Clay. For the Court’s holding with respect to
    Plaintiffs’ second claim, the reader should refer to Judge Cook’s concurring opinion.
    10
    The EPA and States often use general permits for classes of dischargers where there is a basis for the agency
    to establish the same permit conditions for all dischargers in the class. See, e.g., 40 C.F.R. § 122.28. “With a general
    permit, the [agency] issues a permit for specific types of activities and establishes specific rules for complying with the
    permit. Then, rather than apply for an individual permit, operators must file a Notice of Intent (“NOI”) stating that they
    plan to operate under the general permit, and absent a negative ruling by the [agency], discharges that comply with the
    terms of the general permit are automatically authorized.” Texas Indep. Producers & Royalty Owners Assoc. v. EPA,
    
    410 F.3d 964
    , 968 (7th Cir. 2005). Both the EPA and States have found general permits particularly useful for
    discharges of storm water. See 
    id. Kentucky has
    established general permits for several different categories of storm
    water discharges.
    11
    Under 40 C.F.R. § 122.23(b)(1), an animal feeding operation (“AFO”) is defined as “a lot or facility (other
    than an aquatic animal production facility)” in which:
    (i)      Animals (other than aquatic animals) have been, are, or will be stabled or confined
    and fed or maintained for a total of 45 days or more in any 12 month period, and
    (ii)     Crops, vegetation, forage growth, or post-harvest residues are not sustained in the
    normal growing season over any portion of the lot or facility.
    The regulation defines a CAFO as a large or medium AFO. 40 C.F.R. § 122.23(b)(2). In other words, “CAFOs are
    large-scale industrial operations that raise extraordinary numbers of livestock. For example, a ‘Medium CAFO’ raises
    as many as 9,999 sheep, 54,999 turkeys, or 124,999 chickens (other than laying hens). ‘Large CAFOs’ raise even more
    staggering numbers of livestock—sometimes, raising literally millions of animals in one location.” Waterkeeper
    Alliance, Inc. v. EPA, 
    399 F.3d 486
    , 492 (2d Cir. 2005).
    No. 06-5614              Kentucky Waterways, et al. v. Johnson, et al.                          Page 14
    §§ 1(2)(b)(5), (3)(b)(5). The EPA approved most of these exemptions from Tier II review because
    it found them to be de minimus.
    Plaintiffs argue that the EPA’s approval of Kentucky’s categorical exemption of these six
    types of pollution discharges from the Tier II review procedure was arbitrary, capricious and contrary
    to law. In particular, Plaintiffs contend that the EPA acted contrary to law by: (1) failing to ensure
    that each exemption only allowed individual pollution discharges that would not reduce more than
    ten percent of a Tier II water body’s assimilative capacity; (2) failing to provide for a cumulative cap
    on the loss of assimilative capacity caused by the combined effect of discharges allowed under these
    exemptions; and (3) basing its determination of the effect of these exemptions on non-binding
    assurances made by the Cabinet, rather than on the text of the Kentucky regulation itself. Unlike the
    majority, I find each of these arguments persuasive.
    1.      Limit of Ten Percent Destruction of Assimilative Capacity for De
    Minimus Discharges
    The text of 40 C.F.R. § 131.12(a)(2) does not provide for any exceptions to Tier II review
    based on the type or quantity of new sources of pollution, but rather requires that, for waters whose
    quality is better than necessary to support the propagation of fish and wildlife as well as recreation,
    i.e., Tier II waters, “that quality shall be maintained and protected unless the State finds, after full
    satisfaction of the intergovernmental coordination and public participation provisions of the State’s
    continuing planning process, that allowing lower water quality is necessary to accommodate
    important economic or social development in the area in which the waters are located.” (emphasis
    added). Likewise, the CWA does not provide for any exceptions to Tier II antidegradation review
    but instead demands that any revision to effluent limitation standards for Tier II waters be “consistent
    with the antidegradation policy established under this section.” 33 U.S.C. § 1313(d)(4)(B).
    Despite this lack of text-based exceptions to Tier II antidegradation review, the EPA approved
    most of Kentucky’s categorical exemptions to Tier II review for certain types of discharges under the
    administrative law principle which allows an agency to create unwritten exceptions to a statute or rule
    for insignificant or “de minimus” matters. Under this well-established principle, it is “permissible
    as an exercise of agency power, inherent in most statutory schemes,” to create categorical exemptions
    “to overlook circumstances that in context may fairly be considered de minimus.” Alabama Power
    Co. v. Costle, 
    636 F.2d 323
    , 360 (D.C. Cir. 1979). This authority to create exemptions “is not an
    ability to depart from the statute, but rather a tool to be used in implementing the legislative design.”
    
    Id. In other
    words, “this exemption authority is narrow in reach and tightly bounded by the need to
    show that the situation is genuinely de minimus or one of administrative necessity.” 
    Id. at 361.
    Accordingly, an agency only has implied authority to create an exemption “when the burdens of
    regulation yield a gain of trivial or no value.” Greenbaum v. EPA, 
    370 F.3d 527
    , 534 (6th Cir. 2004)
    (quoting Alabama 
    Power, 636 F.2d at 360-61
    ). This “implied authority is not available for a situation
    where the regulatory function does provide benefits, in the sense of furthering the regulatory
    objectives, but the agency concludes that the acknowledged benefits are exceeded by the costs.”
    Alabama 
    Power, 636 F.2d at 361
    . “Determination of when matters are truly de minimus naturally
    will turn on the assessment of particular circumstances, and the agency will bear the burden of
    making the required showing.” 
    Greenbaum, 370 F.3d at 534
    (quoting Alabama 
    Power, 636 F.2d at 360
    ).
    Plaintiffs contend that, in the context of Tier II review, “a narrow reading of the de minimus
    doctrine is appropriate given the clear intent of the federal antidegradation requirements to allow for
    the lowering of water quality only when necessary to accommodate important economic or social
    development in the area.” Pl. Br. at 31 (citing 40 C.F.R. § 131.12(a)(2)). I agree with this
    suggestion and would hold that the EPA’s approval of any exemptions from the Tier II review
    No. 06-5614                   Kentucky Waterways, et al. v. Johnson, et al.                                         Page 15
    process must be based upon a well-founded determination that the pollution discharges permitted
    under such exemptions will have a truly de minimus impact upon the water quality of Tier II waters.12
    In their primary challenge to the EPA’s approval of Kentucky’s categorical Tier II
    exemptions, Plaintiffs contend that the EPA should have ensured that individual discharges allowed
    under these exemptions would not cause more than a specified decrease in water quality. In
    particular, Plaintiffs argue that an exemption for an individual pollution discharge that would 13
    use up
    more than ten percent of a water’s remaining assimilative capacity cannot be de minimus. By
    approving Kentucky’s categorical exemptions without ensuring that they would only exempt new
    discharges that would have an insignificant effect on water quality, Plaintiffs argue, the EPA
    exceeded its legal authority under the CWA and 40 C.F.R. § 131.12(a) to allow de minimus
    exceptions. I agree.
    The EPA has previously indicated that the central purpose of the federal Tier II
    antidegradation regulations is to protect a water body’s assimilative capacity, which is “the difference
    between the applicable water quality criterion for a pollutant parameter and the ambient water quality
    for that parameter when it is better that the criterion.” J.A. at 922 (Memorandum from Ephraim S.
    King, Director of EPA Office of Science and Technology, to Water Management Division Directors,
    Regions 1-10 (Aug. 10, 2005) (hereinafter “King Memorandum”)); accord J.A. at 208 (EPA
    Approval Document). In short, a water body’s assimilative capacity is a measurement of the amount
    by which its quality exceeds levels necessary to support fish, wildlife, and recreation. The Tier II
    review process ensures that this assimilative capacity is maintained so as to avoid further degradation
    of the high quality of Tier II waters. Thus, any exceptions to Tier II review cannot be deemed de
    minimus if they permit new discharges which significantly decrease a Tier II water body’s
    assimilative capacity. Indeed, the EPA has cautioned States against using “a high threshold of
    significance” for creating categorical exemptions, because such an approach could “unduly restrict[]
    the number of proposed activities that are subject to a full antidegradation review” and “may not
    adequately prevent cumulative water quality degradation on a watershed scale.” Water Quality
    Standards Regulation, 63 Fed. Reg at 36,783. The EPA has likewise indicated that, while “the
    current regulation does not specify a significance threshold below which antidegradation review
    would not be required[, the] EPA’s current thinking is that a clear national norm regarding this
    ‘significance test’ is necessary and should be developed and established in either the regulation or
    national guidance.” 
    Id. 12 As
    an initial matter, I question whether such de minimus exceptions should even be allowed for Tier II
    review. The Tier II review process, required by 40 C.F.R. § 131.12(a)(2), does not create a situation where “the burdens
    of regulation yield a gain of trivial or no value.” 
    Greenbaum, 370 F.3d at 534
    (6th Cir. 2004) (quoting Alabama 
    Power, 636 F.2d at 360-61
    ). On the contrary, this Tier II review process directly furthers Congress’ regulatory objective “to
    restore and maintain the chemical, physical, and biological integrity of the Nation’s waters.” 33 U.S.C. § 1251(a)
    (emphasis added). This acknowledged benefit of the protection afforded by the Tier II review procedures cannot be
    ignored by the EPA simply because Tier II review also imposes some economic costs on certain pollutant dischargers.
    Nevertheless, the only court to have considered this issue has not found de minimus exceptions to be
    impermissible in this context. See Ohio Valley, 
    279 F. Supp. 2d
    at 769 (finding that “nothing in the EPA’s regulation
    prohibits a de minimus exception from Tier 2 review when water quality is lowered only a ‘trivial’ amount”). Likewise,
    the EPA has permitted States to create categorical exemptions from Tier II review for discharges whose effect on Tier
    II waters is deemed trivial. See, e.g., Water Quality Standards Regulation, 63 Fed. Reg. at 36,783. Finally, Plaintiffs
    do not directly challenge on appeal the EPA’s authority to permit de minimus exceptions to the requirements of 40 C.F.R.
    § 131.12(a). Given this apparent acceptance of the EPA’s authority to approve de minimus exemptions, I am hesitant
    to conclude that the EPA has acted contrary to law simply by allowing Kentucky to provide for some exemptions to Tier
    II review. However, I agree with Plaintiffs that the EPA’s authority to approve Kentucky’s exemptions from Tier II
    review as de minimus is quite limited.
    13
    Plaintiffs actually seem to argue for a lower threshold, but insist that, regardless, ten percent is the outer limit
    of permissible reduction of assimilative capacity.
    No. 06-5614              Kentucky Waterways, et al. v. Johnson, et al.                         Page 16
    Neither the EPA nor any federal court has previously determined the precise threshold
    between significant and insignificant decreases in assimilative capacity. Nevertheless, the EPA’s
    prior guidance statements indicate that more than a ten percent reduction in assimilative capacity
    would be significant, and thus not de minimus. In its Water Quality Guidance for the Great Lakes
    System Supplementary Information Document (“Great Lakes SID”), issued in 1995, the EPA
    addressed de minimus water degradation in the Great Lakes ecosystem. In particular, the EPA
    allowed States to categorize as de minimus any discharge of non-bioaccumulative chemicals (“non-
    BCCs”) that caused a loss of less than ten percent of the available assimilative capacity. The EPA
    stated:
    Although de minimus provisions do involve non-conservative assumptions, the de
    minimus provisions included in the proposed Guidance are not likely to seriously
    undermine the protection afforded a high quality water body through antidegradation.
    De minimus provisions provide a means for States and Tribes to differentiate between
    actions that will result in an increased loading of a pollutant to a receiving water that
    is likely to have a significant impact on water quality and those that are unlikely to
    do so and focus review efforts on actions that will degrade water quality. It is
    reasonable to assume that loading increases of non-BCCs that will use less than ten
    percent of the remaining assimilative capacity in a water body will have a negligent
    effect on ambient water quality.
    J.A. at 698 (Great Lakes SID) (emphasis added). More recently, the EPA embraced this ten percent
    threshold in the context of Tier II review generally. In a memorandum to the EPA’s Water
    Management Division Directors, the Director of the EPA’s Office of Science and Technology stated:
    EPA has afforded the states and tribes some discretion in determining what constitutes
    a significant lowering of water quality. EPA has accepted a range of approaches to
    defining a “significance threshold” over which a full antidegradation review is
    required. This issue was considered at length in the process of developing the Water
    Quality Guidance for the Great Lakes. Relying on input offered during a four-year
    open public process involving environmental groups, industry representatives, and
    other experts, with numerous opportunities for public input, the directors of the eight
    Great Lakes states and EPA technical experts reached a consensus on a significance
    threshold value of ten percent (10%) of the available assimilative capacity, coupled
    with a cumulative cap. . . . A ten percent (10%) value is within the range of values for
    significance thresholds that EPA has approved in other states as well. EPA considers
    this approach to be workable and protective in identifying those significant lowerings
    of water quality that should receive a full tier 2 antidegradation review, including
    public participation.
    J.A. at 923 (King Memorandum) (emphasis added). The only court to have considered this issue has
    likewise suggested that a ten percent reduction in assimilative capacity is the outer limit for any de
    minimus exception. See Ohio Valley, 
    279 F. Supp. 2d
    at 770 (finding that the EPA’s approval of
    West Virginia’s exception from Tier II review for individual discharges causing up to a ten percent
    loss of available assimilative capacity was reasonable, but failing to indorse the EPA’s approval of
    West Virginia’s twenty percent de minimus provision for cumulative discharges).
    Based on these authorities’ interpretations of the amount of loss of assimilative capacity that
    would be considered significant, I would find that, in order to be considered de minimus (and thus
    permissible as an exception to 40 C.F.R. § 131.12(a)(2)’s requirement that all Tier II waters be
    afforded Tier II review), a categorical exemption from Tier II review must not permit any individual
    discharge that would destroy more than ten percent of a Tier II water’s available assimilative
    capacity. While discharges causing less than a ten percent loss of assimilative capacity might also
    No. 06-5614              Kentucky Waterways, et al. v. Johnson, et al.                        Page 17
    be too significant to be considered de minimus, I find this the ten percent outer limit to be clearly
    supported by the EPA’s own practice. As the EPA in this case did not even consider whether
    Kentucky’s categorical exemptions could allow individual discharges that would cause a significant,
    i.e., more than ten percent, loss of assimilative capacity in Tier II waters, I would hold that the EPA
    acted contrary to law in approving these exemptions as de minimus. For this reason alone, I find
    reversal required and would remand the matter to the EPA, so that it could consider whether
    Kentucky’s categorical exemptions would permit individual discharges that would cause more than
    a ten percent loss of a Tier II water’s assimilative capacity.
    2.      Cumulative Cap on De Minimus Discharges
    Plaintiffs next argue that “[a] second requirement for any de minimus exemption from Tier
    II antidegradation requirements is that such exemption be subject to a cumulative cap, so that
    individual discharges allowed to pass as trivial do not end up having a significant combined impact.”
    Pl. Br. at 34. Again, I agree that such a cumulative cap is required in order for a discharge exemption
    to be permitted as de minimus.
    As already noted, in order to qualify as de minimus, any exemption to the strict requirements
    of Tier II review must only exempt pollution discharges whose combined effect does not lead to a
    significant degradation of a Tier II water body’s quality. While the limit of ten percent destruction
    of assimilative capacity for individual exempted discharges helps to ensure that the exemptions have
    only a trivial impact on water quality, a cumulative cap is necessary to ensure that the combined
    effect of the many discharges allowed under the exemption is truly de minimus. See Shays v. FEC,
    
    414 F.3d 76
    , 115 (D.C. Cir. 2005) (rejecting the Federal Election Commission’s approval of a de
    minimus exemption of $5000 from a campaign finance reform regulation because it was not “an
    obviously trivial amount, considering that donors could give that amount to each and every state,
    district, and local party organization”); Alabama 
    Power, 636 F.2d at 360
    (indicating that an agency’s
    power to find categorical exemptions to statutory schemes is designed to “overlook circumstances
    that in context may fairly be considered de minimus”). Indeed, if a significant degradation of Tier
    II water quality were allowed to occur because of numerous individually exempted de minimus
    discharges, then the non-textual de minimus exception would be allowed to swallow the rule set forth
    in 40 C.F.R. § 131.12(a)’s plain language that a Tier II water’s quality “shall be maintained and
    protected unless” the State determines, after engaging in the Tier II review process, that “allowing
    lower water quality is necessary to accommodate important economic or social development in the
    area in which the waters are located.” (emphasis added).
    Accordingly, the only court to have considered this issue has found that a cumulative cap is
    necessary in order for an exemption to be permitted as de minimus. Ohio Valley, 
    279 F. Supp. 2d
    at
    770. The Ohio Valley court persuasively articulated the rationale for such a cap:
    From the perspective of maintaining the water quality of a Tier 2 water body (which
    is the focus of § 131.12(a)(2)), the de minimus standard for cumulative discharges is
    more important than the de minimus standard for individual discharges; it is the
    former that will dictate the total reduction in available assimilative capacity that a
    water body may undergo without any Tier 2 review. Without a cumulative cap on de
    minimus discharges, individual de minimus discharges could easily consume all of the
    available assimilative capacity for a given pollutant parameter, reducing water quality
    to the minimum level necessary to support existing uses without ever having
    undergone Tier 2 review.
    
    Id. at 770-771.
    Likewise, the EPA has indicated that in order to qualify as de minimus an exemption
    must have a cumulative cap on the reduction of assimilative capacity that may be caused by exempted
    discharges. See J.A. at 923 (King Memorandum) (noting that in defining a “sufficiency threshold”
    No. 06-5614              Kentucky Waterways, et al. v. Johnson, et al.                           Page 18
    for discharges into the Great Lakes the “EPA technical experts reached a consensus on a significance
    threshold value of ten percent (10%) of the available assimilative capacity, coupled with a cumulative
    cap” (emphasis added)).
    In light of the foregoing concerns, I would hold that a cumulative cap on the allowable
    reduction of assimilative capacity is required in order for a categorical exemption to Tier II review
    to be approved as de minimus. Neither party has suggested an appropriate limit for this cumulative
    cap. However, given the previous discussion regarding the significant negative impact on water
    quality caused by the loss of more than ten percent of a water body’s assimilative capacity, I am
    convinced that an exemption that would allow for combined discharges to cause more than a ten
    percent loss of assimilative capacity, i.e., a significant loss of Tier II water quality, cannot, under the
    EPA’s own scientific standards, be considered de minimus. As the EPA never even considered
    whether a cumulative cap is necessary when approving Kentucky’s categorical exemptions, let alone
    whether the combined effect of the individual discharges allowed under such exemptions would fall
    below the requirements of such a cap, I would find that the EPA acted contrary to law in approving
    these exemptions as de minimus. Accordingly, I would reverse the district court’s grant of summary
    judgment to Defendants on Plaintiffs’ challenge to Kentucky’s Tier II review exemptions and remand
    the matter to the EPA. On remand, in addition to considering whether Kentucky’s categorical
    exemptions would permit individual discharges that would cause more than a ten percent loss of a
    Tier II water’s assimilative capacity, I would also require the EPA to evaluate the potential
    cumulative effect of these individual discharges so as to ensure that they do not cause a combined
    loss of more than ten percent of the assimilative capacity of Kentucky’s Tier II waters.
    3.      EPA’s Reliance on Kentucky’s Commitments Regarding Its
    Regulations When Assessing Their Impact as De Minimus
    Finally, Plaintiffs argue that in determining whether Kentucky’s exemptions are in fact de
    minimus, the EPA was not entitled to rely on Kentucky’s unenforceable commitments regarding these
    exemptions, but rather was required to assess the impact of each exemption based solely on the
    language of the exemption itself. I agree that this conclusion is compelled by the federal regulations.
    The EPA’s CWA implementing regulations require each State to include, as part of its water
    quality standards submitted to the EPA for review, “[a]n antidegradation policy consistent with [40
    C.F.R.] § 131.12.” 40 C.F.R. § 131.6(d). These federal regulations further require the State to
    provide “[c]ertification by the State Attorney General or other appropriate legal authority within the
    State that the [submitted] water quality standards were duly adopted pursuant to State law.” 40
    C.F.R. § 131.6(e). Thus, in reviewing Kentucky’s antidegradation rules for compliance with 40
    C.F.R. § 131.12, the EPA must consider only the Kentucky water quality regulations that “were duly
    adopted pursuant to State law.” 40 C.F.R. § 131.6(e).
    Commitments by state agencies, such as the Cabinet, regarding the application of Kentucky’s
    antidegradation implementation procedures do not have the force of law in Kentucky. See Ky. Rev.
    Stat. Ann. § 13A.130(1) (2006) (“An administrative body shall not by internal policy, memorandum,
    or other form of action . . . [m]odify . . . [or] [e]xpand upon or limit a statute or administrative
    regulation.”); Hagan v. Farris, 
    807 S.W.2d 488
    , 490 (Ky. 1991) (“An agency must be bound by the
    regulations it promulgates. . . . KRS 13A.130 prohibits an administrative body from modifying an
    administrative regulation by internal policy or another form of action.”); Kerr v. Ky. State Bd. of
    Registration for Prof’l Eng’rs & Land Surveyors, 
    797 S.W.2d 714
    , 717 (Ky. Ct. App. 1990)
    (“Regulatory agencies are creatures of statute, and have not powers of their own; [their] internally
    adopted policies are null and void, and of no effect whatsoever.”). Accordingly, they may not be
    considered by the EPA when evaluating whether Kentucky’s Tier II review exemptions will have a
    de minimus impact on the quality of Kentucky’s Tier II waters. See Northwest Envtl. Advocates v.
    EPA, 
    268 F. Supp. 2d 1255
    , 1268-69 (D. Or. 2003) (finding that the EPA was not entitled to rely on
    No. 06-5614              Kentucky Waterways, et al. v. Johnson, et al.                          Page 19
    unenforceable commitment from the State when approving state-promulgated environmental
    standards).
    While the Cabinet’s promises or commitments regarding the way in which it will apply
    Kentucky’s antidegradation policies should not be considered when assessing the de minimus effects
    of the categorical exemptions contained in Kentucky’s antidegradation regulations, the Cabinet’s
    interpretations of those regulations may be useful in understanding the effects of their application.
    Kentucky’s duly adopted antidegradation rules and implementation policy are found in 401 Ky.
    Admin. Regs. 5:029 and 5:030. In interpreting these regulations, the EPA must first look to the plain
    language of the regulations themselves. See Baptist Physician Hosp. Org., Inc. v. Humana Military
    Healthcare Serv., Inc., 
    481 F.3d 337
    , 344 (6th Cir. 2007) (“As with all matters of regulatory
    interpretation, we look first to the plain and unambiguous meaning of the regulation, if any.”). If the
    EPA reasonably concludes that Kentucky’s regulations are ambiguous, then it may rely on the
    Cabinet’s interpretation of these regulations, which, if reasonable in light of the regulations’ plain
    language, is entitled to deference. See 
    Auer, 519 U.S. at 462
    ; Defenders of Wildlife v. EPA, 
    415 F.3d 1121
    , 1127 (10th Cir. 2005) (finding it permissible for the EPA to rely on a state environmental
    agency’s interpretation of the State’s antidegradation provisions when reviewing them for compliance
    with 40 C.F.R. § 131.12); 
    Hagan, 807 S.W.2d at 490
    (“In most cases, an agency’s interpretation of
    its own regulations is entitled to substantial deference.”). However, “the EPA may not [permit the
    Cabinet to] effectively rewrite or amend existing state regulations, nor may it ‘escape the notice and
    comment requirements . . . by labeling a major substantive addition to a rule a mere interpretation.’”
    Defenders of 
    Wildlife, 415 F.3d at 1127
    (citing Riverside Cement Co. v. Thomas, 
    843 F.2d 1246
    , 1248
    (9th Cir. 1988), and quoting Appalachian Power Co. v. EPA, 
    208 F.3d 1015
    , 1024 (D.C. Cir. 2000)).
    See also 
    Hagan, 807 S.W.2d at 490
    (“An agency’s interpretation of a regulation is valid, however,
    only if the interpretation complies with the actual language of the regulation.”). Thus, the EPA may
    rely on the Cabinet’s reasonable interpretation of Kentucky’s categorical exemptions from Tier II
    review to the extent that it finds the regulation ambiguous, but it may not rely on the Cabinet’s
    substantive additions to those exemptions when determining their compliance with the requirements
    of 40 C.F.R. § 131.12.
    In the instant case, the EPA relied upon unenforceable commitments made by the Cabinet in
    determining whether the exemptions at issue would have an insignificant effect on the quality of
    Kentucky’s Tier II waters. The language of Kentucky’s antidegradation implementation regulation
    clearly provides that the Tier II review process specified in the regulation “shall not apply” to certain
    specified dischargers. See 401 Ky. Admin. Regs. 5:030 §§ 1(2)(b)(1)(a)-(e), (3)(b)(1)(a)-(e). The
    regulation does not, on its face, provide for an exception to these exemptions in cases where the
    exempted discharge would cause a significant lowering of water quality. Nevertheless, in approving
    these exemptions, the EPA relied on the Cabinet’s commitments that it would not issue discharge
    permits under these exemptions for discharges that would cause a significant lowering of water
    quality. For example, the EPA approved Kentucky’s exemption for discharges subject to storm water
    general permits, in part, because of Kentucky’s indication that “the Commonwealth has determined
    that it will . . . assure that such permits only allow discharges that will not cause a significant
    lowering of water quality.” J.A. at 191 (EPA Approval Document). Likewise in approving the
    exemption for domestic sewage dischargers who accept certain pollutant limits, the EPA noted:
    Kentucky has represented that these default [pollutant] limits will prevent any
    [significant lowering of water quality]. In those rare instances where these default
    limits are not protective of water quality, [the Kentucky Department of Water
    (“KDOW”)] has required more stringent options for permit applicants in the form of
    more stringent limits or a prohibition on discharge. The effect of this provision and
    its implementation by KDOW is to prevent any significant lowering of water quality.
    No. 06-5614              Kentucky Waterways, et al. v. Johnson, et al.                          Page 20
    J.A. at 215 (EPA Approval Document). Finally, in approving the exemptions for CAFO discharges
    and discharges pursuant to KPDES permit renewals that result in less than a twenty percent pollution
    expansion, the EPA explicitly stated that it was relying on the Cabinet’s assurances that it would not
    allow such exemptions to cause a significant lowering of water quality without applying Tier II
    review. See J.A. at 206 (EPA Approval Document) (“By providing that antidegradation review is
    not required for discharges from CAFOs, Kentucky has represented that it will assure that these
    KPDES permits (both individual and general permits) will authorize only those new or increased
    discharges that will not cause significant lowering of water quality. Based on that understanding,
    EPA approves these provisions as revisions to Kentucky’s water quality standards.”); J.A. at 209
    (EPA Approval Document) (“EPA’s analysis shows that it is possible that, in limited situations, a
    20% expansion could use more than 10% of the available assimilative capacity of the receiving water,
    or could leave little assimilative capacity after the expansion. However, Kentucky stated in its April
    11, 2005, letter that if such situations arise, the Commonwealth would require an antidegradation
    review. In light of EPA’s analyses and Kentucky’s assurances, EPA is approving this provision.”).
    These commitments made by the Cabinet cannot reasonably be construed as mere interpretations of
    401 Ky. Admin. Regs. 5:030, and the EPA was not entitled to rely upon them in evaluating the de
    minimus impact of the regulation on the quality of Kentucky’s Tier II waters.
    In my view, the EPA acted contrary to law by relying on these unenforceable commitments.
    Accordingly, I would find this last contention by Plaintiffs to be a third reason to reverse the district
    court’s grant of summary judgment to Defendants with respect to the EPA’s approval of Kentucky’s
    six categorical exemptions from Tier II review and to remand the matter to the EPA. In determining,
    on remand, whether Kentucky’s regulatory exemptions to Tier II review only exempt discharges that
    have an insignificant effect on Tier II water quality, I would require the EPA to focus primarily on
    the language of 401 Ky. Admin. Regs. 5:030. In particular, I would prohibit the EPA from relying
    on unenforceable commitments from the Cabinet concerning its methods for implementing that
    regulation.
    IV. CONCLUSION
    For the reasons expressed in parts I, II, and III-A of this opinion as well as for the reasons
    expressed in Judge Cook’s concurring opinion below, we AFFIRM in part and REVERSE in part
    the opinion and order of the district court. We AFFIRM the district court’s grant of summary
    judgment to Defendants on Plaintiffs’ challenge to the EPA’s approval of Kentucky’s selection of
    Tier II waters. However, we REVERSE the district court’s grant of summary judgment to
    Defendants with respect to Plaintiffs’ challenge to the EPA’s approval of Kentucky’s categorical
    exemption of six types of pollution discharges from Tier II review. We thus VACATE that portion
    of the EPA’s decision approving Kentucky’s categorical exemption of certain discharges from Tier
    II review, and REMAND this matter to the EPA so that it may review this aspect of Kentucky’s
    antidegradation implementation procedures in a manner that is consistent with Judge Cook’s
    concurring opinion.
    No. 06-5614                  Kentucky Waterways, et al. v. Johnson, et al.                                     Page 21
    _________________
    CONCURRENCE
    _________________
    COOK, Circuit Judge, concurring, joined by SILER, Circuit Judge. While we join parts I,
    II, III-A, and IV of Judge Clay’s opinion, we write separately to express the Court’s holding with
    respect to Plaintiffs’ second claim—that the EPA erred in approving Kentucky’s six exemptions from
    Tier II review. For the reasons that follow, we find that the EPA did err in approving these
    exemptions, and thus REVERSE the district court’s grant of summary judgment to the EPA on this
    point and REMAND the matter to the EPA for further proceedings consistent with this opinion.
    I.
    A.
    Kentucky’s antidegradation regulations require new or expanded discharges into
    “exceptional” or “high quality” waters to pass Tier II review, but exempt five categories of
    discharges, designating them as causing insignificant water-quality loss. These discharges are:
    1.       Any expanded discharge under a renewed or modified KPDES permit, so long as the
    expansion does not increase pollutant loading by 20% or more;
    2.       Industrial discharges if the emitter discharges pollutants at less than half the
    concentration authorized by a normal KPDES water permit;
    3.       Domestic discharges if the emitter limits seven pollutants below certain targets—for
    example, residual chlorine to “no greater than 0.010 milligrams per liter”;
    4.       Discharges under storm water general permits;1 and
    5.       Discharges from concentrated animal feeding operations (“CAFOs”).2
    See 401 Ky. Admin. Reg. 5:030 §§ 1(2)(b)(1)(a),(d),(e); 1(2)(b)(4)-(6); 1(3)(b)(1)(a),(d),(e);
    1(3)(b)(2)-(4).
    Unless a statute or regulation employs “extraordinarily rigid” language, courts recognize an
    administrative law principle that allows agencies to create unwritten exceptions to a statute or rule
    for “de minimis” matters. Greenbaum v. EPA, 
    370 F.3d 527
    , 534 (6th Cir. 2004); see also Ober v.
    Whitman, 
    243 F.3d 1190
    , 1193–95 (9th Cir. 2001) (finding that the EPA may “exempt de minimis
    sources of [a pollutant] from [Clean Air Act] pollution controls”). Under this principle, it is
    1
    “With a general permit, the EPA issues a permit for specific types of activities and establishes specific rules
    for complying with the permit. Then, rather than apply for an individual permit, operators must file a Notice of Intent
    (‘NOI’) stating that they plan to operate under the general permit, and absent a negative ruling by the EPA, discharges
    that comply with the terms of the general permit are automatically authorized.” Tex. Indep. Producers & Royalty Owners
    Ass’n v. EPA, 
    410 F.3d 964
    , 968 (7th Cir. 2005).
    2
    “CAFOs are large-scale industrial operations that raise extraordinary numbers of livestock. For example, a
    ‘Medium CAFO’ raises as many as 9,999 sheep, 54,999 turkeys, or 124,999 chickens (other than laying hens). ‘Large
    CAFOs’ raise even more staggering numbers of livestock—sometimes, raising literally millions of animals in one
    location.” Waterkeeper Alliance, Inc. v. EPA, 
    399 F.3d 486
    , 492 (2d Cir. 2005) (footnotes omitted).
    No. 06-5614              Kentucky Waterways, et al. v. Johnson, et al.                         Page 22
    “permissible as an exercise of agency power, inherent in most statutory schemes, to overlook
    circumstances that in context may fairly be considered de minimis.” Ala. Power Co. v. Costle, 
    636 F.2d 323
    , 360 (D.C. Cir. 1979). This authority “is not an ability to depart from the statute, but rather
    a tool to be used in implementing the legislative design.” 
    Id. An agency
    thus has the implied
    authority to exempt “‘when the burdens of regulation yield a gain of trivial or no value.’”
    
    Greenbaum, 370 F.3d at 534
    (quoting Ala. 
    Power, 636 F.2d at 360
    –61). “‘Determination of when
    matters are truly de minimis naturally will turn on the assessment of particular circumstances, and
    the agency will bear the burden of making the required showing.’” 
    Id. (quoting Ala.
    Power, 636
    F.2d at 360
    ).
    Though Plaintiffs accept the EPA’s authority to approve de minimis exemptions to § 131.12,
    they challenge the EPA’s conclusion that the five exemptions listed above will result in only
    “insignificant” water degradation; Plaintiffs contend that these exemptions eviscerate Kentucky’s
    Tier II review process, allowing significant degradations in water quality without demonstrated
    necessity.
    To assess whether Kentucky’s regulations permit significant degradation, we normally turn
    to the EPA’s calculations. See Citizens Coal 
    Council, 447 F.3d at 890
    (reiterating that courts must
    afford the highest level of deference to the EPA’s technical or scientific evaluations). Because
    § 131.12 protects assimilative capacity, we necessarily focus on how much assimilative capacity
    would be lost by utilization of the five Tier II exemptions. See JA 922 (Memorandum from Ephraim
    S. King, Director of EPA Office of Science and Technology, to Water Management Division
    Directors, Regions 1-10 (Aug. 10, 2005)) (stating proposed regulations “need to be very carefully
    evaluated to determine how they translate to reduction in assimilative capacity in order to understand
    whether a significant decrease in assimilative capacity will occur”). Relying on the EPA’s
    assimilative-capacity-loss estimates, we must determine de novo whether this loss is significant or
    merely de minimis.
    While the EPA’s decision document in this case offers detailed technical analysis, it fails to
    aim its analysis at the legally operative question: will the extent to which various emitters avail
    themselves of the exemptions result in significant, rather than de minimis, degradation? The EPA
    measured Kentucky’s § 131.12 compliance by assessing whether each individual exemption resulted
    in “significant” or “insignificant” degradation, but that approach avoids assessing the exemptions’
    cumulative effects on the State’s antidegradation compliance. Because § 131.12 regulates
    degradation, not individual sources of degradation, see 
    id. (“The State
    shall develop and adopt a
    statewide antidegradation policy and identify the methods for implementing such policy pursuant to
    this subpart.”), the legally relevant inquiry is whether Kentucky’s Tier-II-review exemptions together
    permit significant degradation, see Ohio Valley, 
    279 F. Supp. 2d
    at 770 n.3 (“From the perspective
    of water quality . . . it does not matter whether the number of discharges is one or one hundred; the
    relevant question is how much water quality is lowered by any and all discharges into a water body”).
    The EPA’s decision document avoids answering this question, and we accordingly lack the
    information needed to meaningfully review the EPA’s decision to approve Kentucky’s regulations.
    See Motor Vehicle Mfrs. 
    Ass’n, 463 U.S. at 43
    (holding that an agency action is arbitrary and
    capricious if the agency has “entirely failed to consider an important aspect of the problem”).
    Moreover, though the EPA’s decision document details the tests conducted to measure each
    exemption’s impact, the document often fails to include the resulting measurements—i.e., the EPA’s
    estimate as to how much assimilative capacity would be lost. Instead, the EPA concludes only that
    the tests show “insignificant” degradation will occur. We cannot review this legal conclusion’s
    reasonableness without the EPA’s first discussing its assimilative-capacity loss estimates and
    explaining why it deems them insignificant. See 
    id. (stating that
    a reviewing court “may not supply
    a reasoned basis for the agency’s action that the agency itself has not given”). We thus find a remand
    No. 06-5614              Kentucky Waterways, et al. v. Johnson, et al.                          Page 23
    to the EPA necessary so that it may address these deficiencies in its consideration of Kentucky’s de
    minimis exemptions.
    B.
    Having determined that the EPA’s approval of five of Kentucky’s six exemptions must be
    reconsidered, we turn to the remaining exemption for coal-mining discharges. Unlike the de minimis
    exemptions, Kentucky carved this exception out of its general antidegradation provisions believing
    that its existing coal-mining regulations satisfy § 131.12’s requirements. JA 192–93. The EPA
    evaluated these existing regulations and agreed that they complied with § 131.12, acknowledging the
    five steps Kentucky takes before issuing a permit for a coal-mining discharge into Tier II waters.
    Taking issue with one discrete aspect of the EPA’s approval, Plaintiffs contend that the EPA
    erroneously credited Kentucky’s existing regulations as requiring coal-mining dischargers to
    demonstrate economic or social necessity when, in fact, the regulations do not. Indeed, Kentucky’s
    “socioeconomic review” is found not in its water-quality regulations, but in an informal commitment
    to the EPA. See JA 253. The Plaintiffs insist that the EPA may not rely on such promises, and we
    agree.
    Kentucky agreed to subject proposed coal-mining discharges to socioeconomic review during
    the EPA’s audit of its antidegradation procedures. When the EPA probed Kentucky about how it
    determined socioeconomic necessity for coal-mining discharges, the Cabinet replied that Kentucky
    “believes that the socioeconomic importance of coal mining is well documented . . . and supported
    by sufficient data, so that a demonstration of importance for each coal mining activity is not
    required.” JA 298. Finding this explanation unsatisfactory, the EPA pressed for more. See 40 C.F.R.
    § 131.12(a)(2) (requiring a demonstration that degradation in Tier II waters is “necessary to
    accommodate important economic or social development in the area in which the waters are located”
    (emphasis added)). Through a response letter, the Cabinet assured the EPA that prior to issuing
    KPDES coal-mining permits to discharge into Tier II waters, it would “interpret” its existing
    regulations governing such permits to require a showing that the “discharge is from an activity of
    important social or economic development to the area in which the waters are located.” JA 253.
    Relying on this commitment, the EPA approved the coal-mining exemption. JA 194–95.
    The Plaintiffs maintain that Kentucky’s response letter “effectively amended” the regulations
    outside the State’s procedure for promulgating or modifying administrative rules. See Ky. Rev. Stat.
    Ann. § 13A.130(1) (“An administrative body shall not by internal policy, memorandum, or other
    form of action . . . [m]odify . . . [or] [e]xpand upon or limit a statute or administrative regulation.”).
    The EPA counters that Kentucky’s letter did not amend its regulations but merely furnished the
    State’s interpretation.
    The EPA may clarify ambiguous state regulations by consulting with the state and relying on
    authorized state interpretations, see Defenders of Wildlife v. EPA, 
    415 F.3d 1121
    , 1127–28 (10th Cir.
    2005) (holding that the EPA could rely on a state’s interpretation of an ambiguous water quality
    standard, so long as the EPA did not “effectively rewrite or amend” it), but that is not what happened
    here. Kentucky’s Tier II exemption for coal-mining discharges was not ambiguous. The
    antidegradation regulations stated, in explicit terms, that Tier II review “shall not apply” to coal-
    mining discharges regulated under existing regulations. See 401 Ky. Admin. Reg. 5:030
    §§ 1(2)(b)(1)(b), 1(3)(b)(1)(b). Those existing regulations do not require socioeconomic review.
    Indeed, when the EPA first queried the State on socioeconomic review for coal-mining discharges,
    the State responded that there was no such review. JA 298. Only after further inquiries from the
    EPA did Kentucky adopt a starkly different position—that its regulations (it did not cite a particular
    one) compelled a socioeconomic review for each proposed discharge. JA 253.
    No. 06-5614             Kentucky Waterways, et al. v. Johnson, et al.                      Page 24
    This securing an informal commitment from a state agency rather than requiring the state to
    amend its regulations violates the federal approval procedure established by 33 U.S.C.
    § 1313(c)(3)—the EPA either approves or disapproves the regulations proposed by a state. See
    Riverside Cement Co. v. Thomas, 
    843 F.2d 1246
    , 1248 (9th Cir. 1988); Ohio Valley, 
    279 F. Supp. 2d
    at 756 (finding the EPA’s strained reading of an unambiguous West Virginia regulation to be “an
    impermissible attempt to amend the regulation”); Natural Res. Defense Council v. EPA, 
    16 F.3d 1395
    , 1399 (4th Cir. 1993) (“EPA sits in a reviewing capacity of the state-implemented standards,
    with approval and rejection powers only.”) (citing 33 U.S.C. § 1313(c)). Short-circuiting the normal
    promulgation process by addressing deficiencies through agency commitments not only contravenes
    § 1313(c)(3), but also hinders an important objective—public participation in the rule-making
    process. See generally Appalachian Power Co. v. EPA, 
    208 F.3d 1015
    , 1024 (D.C. Cir. 2000)
    (stating the EPA may not “escape the notice and comment requirements . . . by labeling a major
    substantive legal addition to a rule a mere interpretation”). Enforceability also argues against the
    EPA’s reliance on informal state commitments. See, e.g., Riverside 
    Cement, 843 F.2d at 1247
    (an
    informal state interpretation at odds with a regulation’s text is the “bureaucratic equivalent of an
    illusory contract”); Nw. Envtl. Advocates v. EPA, 
    268 F. Supp. 2d 1255
    , 1269 (D. Or. 2003) (finding
    the EPA erred by relying on an “unenforceable promise”—the state’s informal commitment to use
    a more protective water standard—to approve certain Clean Water Act regulations). Because the
    EPA relied on an informal Cabinet commitment to approve Kentucky’s Tier II exemption for coal-
    mining discharges, we find that the agency’s approval was “not in accordance with law.” 5 U.S.C.
    § 706(2). Accordingly, we hold that this exemption too requires remand to the EPA for
    reconsideration.
    II.
    For the these reasons, we REVERSE the district court’s grant of summary judgment to the
    EPA on Plaintiffs’ challenge to the approval of Kentucky’s six Tier-II-review exemptions and
    REMAND this matter for further proceedings consistent with this opinion.
    

Document Info

Docket Number: 06-5614

Filed Date: 9/3/2008

Precedential Status: Precedential

Modified Date: 9/22/2015

Authorities (30)

Defenders of Wildlife v. United States Environmental ... , 415 F.3d 1121 ( 2005 )

American Wildlands v. Browner , 260 F.3d 1192 ( 2001 )

Dolores K. Jones v. Metropolitan Life Insurance Company, ... , 385 F.3d 654 ( 2004 )

Baptist Physician Hospital Organization, Inc. And Baptist ... , 481 F.3d 337 ( 2007 )

waterkeeper-alliance-inc-american-farm-bureau-federation-national , 399 F.3d 486 ( 2005 )

natural-resources-defense-council-incorporated-environmental-defense-fund , 16 F.3d 1395 ( 1993 )

Texas Independent Producers and Royalty Owners Association ... , 410 F.3d 964 ( 2005 )

Riverside Cement Company v. Lee M. Thomas, Administrator, ... , 843 F.2d 1246 ( 1988 )

Diane M. Moon v. Unum Provident Corporation , 405 F.3d 373 ( 2005 )

Coalition for Government Procurement v. Federal Prison ... , 365 F.3d 435 ( 2004 )

robert-greenbaum-sierra-club-intervenor-v-united-states-environmental , 370 F.3d 527 ( 2004 )

City of Cleveland v. Ohio , 508 F.3d 827 ( 2007 )

Edward M. Ober Robin d.silver David Matusow Sandra L. Bahr ... , 243 F.3d 1190 ( 2001 )

james-mcdonald-v-western-southern-life-insurance-company-western-southern , 347 F.3d 161 ( 2003 )

Shays v. Federal Election Commission , 414 F.3d 76 ( 2005 )

Appalachian Power Co. v. Environmental Protection Agency , 208 F.3d 1015 ( 2000 )

Hagan v. Farris , 807 S.W.2d 488 ( 1991 )

national-wildlife-federation-v-anne-gorsuch-in-her-official-capacity-as , 693 F.2d 156 ( 1982 )

Motor Vehicle Mfrs. Assn. of United States, Inc. v. State ... , 103 S. Ct. 2856 ( 1983 )

Kentucky Waterways Alliance v. Johnson , 426 F. Supp. 2d 612 ( 2006 )

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