                              PRECEDENTIAL

     UNITED STATES COURT OF APPEALS
          FOR THE THIRD CIRCUIT
             ________________

                No. 13-4079


   AMERICAN FARM BUREAU FEDERATION;
      PENNSYLVANIA FARM BUREAU;
        THE FERTILIZER INSTITUTE;
       NATIONAL CHICKEN COUNCIL;
UNITED STATES POULTRY & EGG ASSOCIATION;
   NATIONAL PORK PRODUCERS COUNCIL;
  NATIONAL CORN GROWERS ASSOCIATION;
 NATIONAL TURKEY FEDERATION; NATIONAL
     ASSOCIATION OF HOME BUILDERS

                    v.

     UNITED STATES ENVIRONMENTAL
          PROTECTION AGENCY;


     CHESAPEAKE BAY FOUNDATION INC;
   CITIZENS FOR PENNSYLVANIA’S FUTURE;
          DEFENDERS OF WILDLIFE;
JEFFERSON COUNTY PUBLIC SERVICE DISTRICT;
   MIDSHORE RIVERKEEPER CONSERVANCY;
      NATIONAL WILDLIFE FEDERATION;
     VIRGINA ASSOCIATION OF MUNICIPAL
        WASTEWATER AGENCIES, INC.;
  MARYLAND ASSOCIATION OF MUNICIPAL
         WASTEWATER AGENCIES;
    NATIONAL ASSOCIATION OF CLEAN
            WATER AGENCIES;
  PENNSYLVANIA MUNICIPAL AUTHORITIES
              ASSOCIATION;
      CITY OF ANAPOLIS, MARYLAND

                         (Intervenors in D.C.)

                   American Farm Bureau Federation;
                   Pennsylvania Farm Bureau;
                   The Fertilizer Institute; National
                   Chicken Council; U.S. Poultry & Egg
                   Association; National Pork Producers
                   Council; National Corn Growers
                   Association; National Turkey
                   Federation; National Association of
                   Home Builders,

                                     Appellants
                ________________

    Appeal from the United States District Court
      for the Middle District of Pennsylvania
      (D.C. Civil Action No. 1-11-cv-00067)
    District Judge: Honorable Sylvia H. Rambo


            Argued November 18, 2014

Before: AMBRO, SCIRICA, and ROTH, Circuit Judges




                         2
                (Opinion filed: July 6, 2015)

Paul J. Bruder, Esquire
Amanda J. Lavis, Esquire
Robert J. Tribeck, Esquire
Rhoads & Sinon
One South Market Square
P.O. Box 1146, 12th Floor
Harrisburg, PA 17108

Kirsten L. Nathanson, Esquire
Richard E. Schwartz, Esquire (Argued)
David Y. Chung, Esquire
Crowell & Moring
1001 Pennsylvania Avenue, N.W.
Washington, DC 20004

Ellen Steen, Esquire
Danielle Quist, Esquire
American Farm Bureau Federation
600 Maryland Avenue, S.W., Suite 1000W
Washington, DC 20024

Gregg I. Adelman, Esquire
William D. Auxer, Esquire
Marc B. Kaplin, Esquire
Kaplin, Stewart, Meloff, Reiter & Stein
910 Harvest Drive
P.O. Box 3037
Blue Bell, PA 19422

      Counsel for Appellants




                               3
Stephen R. Cerutti, II, Esquire
Office of United States Attorney
228 Walnut Street, P.O. Box 11754
220 Federal Building and Courthouse
Harrisburg, PA 17108


Robert G. Dreher
   Acting Assistant Attorney General
Kent E. Hanson, Esquire
J. David Gunter, II, Esquire (Argued)
James Curtin, Esquire
Christopher Day, Esquire
Kelly Gable, Esquire
United States Department of Justice
Environmental Defense Section
Environment & Natural Resources Division
P.O. Box 7415
Washington, DC 20044

      Counsel for Appellee, US EPA

John A. Mueller, Esquire (Argued)
Chesapeake Bay Foundation
6 Herndon Avenue
Annapolis, MD 21403

Lee Ann H. Murray, Esquire
Chesapeake Bay Foundation
614 North Front Street, Suite G
The Old Water Works Building




                             4
Harrisburg, PA 17019

Richard A. Parrish, Esquire
Southern Environmental Law Center
201 West Main Street, Suite 14
Charlottesville, VA 22901

      Counsel for Intervenor Appellees:
      Chesapeake Bay Foundation,
      Citizens for Pennsylvania’s Future,
      Defenders of Wildlife,
      Jefferson County Public Service District,
      Midshore Riverkeeper Conservancy,
      National Wildlife Federation

Lisa M. Ochsenhirt, Esquire
Christopher D. Pomeroy, Esquire (Argued)
Justin W. Curtis, Esquire
Carla S. Pool, Esquire
AquaLaw
6 South 5th Street
Richmond, VA 23219

      Counsel for Intervenor Appellees:
      Virginia Association of Municipal Wastewater
      Agencies, Inc., Maryland Association of Municipal
      Wastewater Agencies, National Association of Clean
      Water Agencies




                             5
Steven A. Hann, Esquire (Argued)
Hamburg, Rubin, Mullin, Maxwell & Lupin
375 Morris Road
P.O. Box 1479
Landsdale, PA 19446

      Counsel for Intervenor Appellee
      Pennsylvania Municipal Authorities Association

Cory L. Andrews, Esquire
Richard A. Samp, Esquire
Washington Legal Foundation
2009 Massachusetts Avenue, N.W.
Washington, DC 20036

      Counsel for Amici Appellants:
      Representatives Robert Aderholt, Lou Barletta,
      Joe Barton, Marsha Blackburn, Kevin Brady,
      Chris Collins, Doug Collins, Scott Desjarlais,
      Jeff Duncan, John Fleming, Bob Gibbs,
      Louie Gohmert, Bob Goodlatte, Sam Graves,
      Morgan Griffith; Brett Guthrie, Andy Harris,
      Vicky Hartzler, Tim Huelskamp, Robert Hurt,
      Billy Long, Frank Lucas, Blaine Luetkemeyer,
      Thomas Massie, David McKinley, Randy Neugebauer,
      Scott Perry, Collin Peterson, Robert Pittenger,
      Mike Pompeo, Todd Rokita, Dennis A. Ross,
      Kurt Schrader, Bill Shuster, Adrian Smith,
      Glenn Thompson, Scott Tipton, Pat Toomey,
      David Vitter, Washington Legal Foundation.

Zachary W. Carter
  Corporation Counsel of the City of New York




                            6
Hilary Meltzer, Esquire
Haley Stein, Esquire
Scott N. Shorr, Esquire
New York City Law Department
100 Church Street
New York, NY 10007

      Counsel for Amici Appellees:
      City of New York, City of Baltimore MD,
      City of Chicago, City of Los Angeles,
      City of Philadelphia, City of San Francisco,
      County of San Francisco.

Stuart A. Raphael
  Solicitor General of Virginia
Trevor S. Cox
  Deputy Solicitor General
Mark R. Herring
  Attorney General of Virginia
Cynthia E. Hudson
  Chief Deputy Attorney General
John W. Daniel, II
  Deputy Attorney General
Joshua D. Heslinga
  Assistant Attorney General
Office of Attorney General of Virginia
900 East Main Street
Richmond, VA 23219

      Counsel for Amicus Appellee
      Commonwealth of Virginia




                             7
Allison M. LaPlante, Esquire
Lewis & Clark Law School
Earthrise Law Center
10015 Southwest Terwilliger Boulevard
Portland, OR 97219

      Counsel for Individual Amici Appellees:
      Robert W. Adler, William Andreen, Michael C.
      Blumm, David Case, Jamison E. Colburn, Victor B.
      Flatt, William Funk, Professor Craig N. Johnston,
      Jeffrey G. Miller, Patrick Parenteau, Robert Percival,
      Zygmunt J.B. Plater, Melissa Powers, Kalyani
      Robbins, Daniel Rohlf, Erin Ryan, Gerald Torres.

Justin M. Gundlach, Esquire
Hope M. Babcock, Esquire
Brian S. Wolfman, Esquire
600 New Jersey Avenue, N.W.
Washington, DC 20001

      Counsel for Amici Appellees:
      Alliance for the Great Lakes, Apalachicola
      Riverkeeper, Card Sound Yachts Inc., Charleston
      Waterkeeper Chattahoochee Riverkeeper, Cook
      Inletkeeper, Grand Riverkeeper, Grand Traverse
      Baykeeper, Gulf Restoration Network, Hoosier
      Environmental Law Center, Kansas Riverkeeper for
      Friends of the Kaw, Kentucky Resources Council,
      Kentucky Waterways Alliance, Lower Mississippi
      Riverkeeper, Missouri Coalition for Environment,
      National Parks Conservation Association, Nebraska
      Wildlife Federation, Ocean Reed Conservation
      Association, One World Adventure Co., Ozark




                             8
      Society, Save The Dunes, Upper Missouri
      Waterkeeper, Utah Rivers Council, West Virginia
      Rivers Coalition, Wyoming Outdoor Council.

Derek Schmidt
   Kansas Attorney General
Jeffrey A. Chanay
   Deputy Attorney General
Bryan C. Clark
   Assistant Solicitor General
Office of Attorney General of Kansas, Room 301
120 Southwest Tenth Avenue, Second Floor
Topeka, KS 66612

Chris Koster
   Missouri Attorney General
Gregory F. Zoeller
  Indiana Attorney General
Luther Strange
   Alabama Attorney General
Michael C. Geraghty
   Alaska Attorney General
Dustin M. McDaniel
   Arkansas Attorney General
Pamela Jo Bondi
   Florida Attorney General
Samuel S. Olens
   Georgia Attorney General
Jack Conway
   Kentucky Attorney General
James D. Caldwell
   Louisiana Attorney General
Bill Schuette




                                9
   Michigan Attorney General
Timothy C. Fox
   Montana Attorney General
Jon Bruning
   Nebraska Attorney General
Wayne Stenehjem
   North Dakota Attorney General
E. Scott Pruitt
   Oklahoma Attorney General
Alan Wilson
   South Carolina Attorney General
Marty J. Jackley
   South Dakota Attorney General
Gregg Abbott
   Texas Attorney General
Sean D. Reyes
   Utah Attorney General
Patrick Morrisey
   West Virginia Attorney General
Peter K. Michael
   Wyoming Attorney General

      Counsel for Amicus Appellants:
      States of Alabama, Alaska, Arkansas, Florida,
      Georgia, Indiana, Kansas, Kentucky, Louisiana,
      Michigan, Missouri, Montana, Nebraska,
      North Dakota, Oklahoma, South Carolina,
      South Dakota, Texas, Utah, West Virginia,
      Wyoming.




                            10
Brooks M. Smith, Esquire
Troutman Sanders, LLP
1001 Haxall Point, 15th Floor
Richmond, VA 23219

Maria V. Souder, Esquire
Troutman Sanders, LLP
600 Peachtree Street, NE, Suite 5200
Atlanta, GA 30308

      Counsel for Amici Appellees:
      Clearfield County Pennsylvania,
      County of Cambria,
      County of Hardy West Virginia,
      County of Pendleton West Virginia,
      County of Perry, County of Tioga,
      Lancaster County, New Castle County,

William P. Bowden, Esquire
Amanda M. Winfree Herrmann, Esquire
Ashby & Geddes
500 Delaware Avenue, 8th Floor
P.O. Box 1150
Wilmington, DE 19899

Russell B. Stevenson, Jr., Esquire
733 Dividing Road
Severna Park, MD 21146

Ridgway Hall, Esquire
3500 Ordway Street, NW
Washington, DC 20016




                                11
      Counsel for Amicus Appellee
      City of Annapolis

Bradley I.B. Marshall, Esquire
Earthjustice
111 South Martin Luther King Jr. Blvd
Tallahassee, FL 32301

      Counsel for Amici Appellees:
      Conservancy of Southwest Florida,
      Environmental Confederation of Southwest Florida,
      Florida Wildlife Federation, Sierra Club,
      St. Johns Riverkeeper

Douglas F. Gansler
  Attorney General of Maryland
Peter K. Killough
Steven R. Johnson
Paul N. De Santis
  Assistant Attorneys General
Office of the Attorney General
People’s Insurance Counsel
200 St. Paul Place
Baltimore, MD 21202

Matthew Denn
  Attorney General of Delaware
820 N. French Street, 6th Floor
Wilmington, DE 19801

Irvin B. Nathan
   Attorney General for the District of Columbia
One Judiciary Square




                             12
441 Fourth Street, N.W.
Washington, DC 20001

          Counsel for Amici Appellees:
          States of Delaware, Maryland,
          District of Columbia



                       OPINION OF THE COURT


AMBRO, Circuit Judge

                                       Contents

I.   Introduction ............................................................................................................... 14
II.  Background ............................................................................................................... 15
   A. The Chesapeake Bay, 1608–1972 ......................................................................... 15
   B. The Clean Water Act, 1972 ................................................................................... 17
   C. Definition and Development of TMDLs, 1972–2000 ........................................... 20
   D. The Chesapeake Bay TMDL, 2000–2010 ............................................................. 23
   E. Procedural Background, 2011–Present ................................................................. 25
III.    Jurisdiction ............................................................................................................ 25
   A. Standing ................................................................................................................. 26
   B. Ripeness................................................................................................................. 27
IV.     Merits..................................................................................................................... 28
   A. Framework for our Decision ................................................................................. 29
   B. Chevron Step One ................................................................................................. 31
     1. Case Law on TMDLs ....................................................................................... 31
     2. Statutory Text ................................................................................................... 34
     3. Statutory Structure and Purpose ....................................................................... 37




                                            13
      i.   Allocations Between Point and Nonpoint
      Sources .................................................................................................................. 38
      ii. “Deadlines” or “Target Dates”...................................................................... 40
      iii. Reasonable Assurance .................................................................................. 41
      iv. Summary of Structure and Purpose .............................................................. 41
    4. Avoidance Canons ............................................................................................ 42
      i.   Federalism ..................................................................................................... 43
      ii. Constitutional Avoidance.............................................................................. 49
    5. Conclusion With Respect to Step One ............................................................. 53
  D. Chevron Step Two ................................................................................................. 53
V. Conclusion ................................................................................................................. 60


I.        Introduction

        The Environmental Protection Agency (“EPA”)
published in 2010 the “total maximum daily load” (“TMDL”)
of nitrogen, phosphorous, and sediment that can be released
into the Chesapeake Bay (the “Bay”) to comply with the
Clean Water Act, 33 U.S.C. § 1251 et seq.. The TMDL is a
comprehensive framework for pollution reduction designed to
“restore and maintain the chemical, physical, and biological
integrity” of the Bay, 33 U.S.C. § 1251, the subject of much
ecological concern over several decades.

        Trade associations with members who will be affected
by the TMDL’s implementation—the American Farm Bureau
Federation, the National Association of Home Builders, and
other organizations for agricultural industries that include
fertilizer, corn, pork, and poultry operations (collectively,
“Farm Bureau”)—sued. They allege that all aspects of the
TMDL that go beyond an allowable sum of pollutants (i.e.,
the most nitrogen, phosphorous, and sediment the Bay can
safely absorb per day) exceeded the scope of the EPA’s




                                           14
authority to regulate, largely because the agency may intrude
on states’ traditional role in regulating land use.

       The District Court ruled against Farm Bureau, and it
appeals. For the reasons that follow, we side with the EPA
and affirm the District Court’s ruling.

II.   Background

       The EPA and seven states—Virginia, West Virginia,
Maryland, Delaware, Pennsylvania, New York, and the
District of Columbia, which is a “state” for Clean Water Act
purposes, 33 U.S.C. § 1362(3)—have engaged in a decades-
long process to develop a plan to improve the quality of the
water in the Chesapeake Bay, the largest estuary in North
America. The Bay’s watershed area of 64,000 square miles
contains tens of thousands of lakes, rivers, streams and
creeks. The Bay itself has a surface area of 4,500 square
miles, and it has 11,684 miles of shoreline, longer than the
coastline from San Diego, California to Seattle, Washington.
      A.      The Chesapeake Bay, 1608–1972

        Before Europeans settled the Bay, it supported much
sea life. As two associates of John Smith wrote, “Neither
better fish more plenty or variety had any of us ever seene, in
any place swimming in the water, then in the bay of
Chesapeack.” Walter Russell & Anas Todkill et al., The
Accidents that Happened in the Discoverie of the Bay, in 1
The Complete Works of Captain John Smith (1580–1631)
Philip L. Barbour, ed., 224, 228 (1986). The fertile land of
the watershed and the beauty and commercial value of the
Bay proved attractive. By 1950 about 7,000,000 people lived
in the watershed; today it is home to 17,000,000, and by 2030
the population may reach 20,000,000.




                              15
        The watershed area not only sustains its growing
human population; it also supports a great deal of commerce,
including fishing, shipping, farming, and tourism. All these
activities, as well as other incidents of daily life, contribute
pollutants to the Bay. As a result, it is plagued by dead zones
with opaque water and algae blooms that render significant
parts of it unable to support aquatic life. Surrounding
jurisdictions recognize that the Bay absorbs far too much
nitrogen, phosphorous, and sediment to be the healthy
ecosystem it once was. These threats to the Bay (and to the
livelihood of many who depend on its bounty) have been
known for a long time both to scientists and to observant lay
people. As a Pulitzer-Prize winning chronicler of Bay life put
it:

       Coliform bacteria indices, atomic plant pass-
       throughs,        siltation-caused        reduced
       photosynthetic capabilities, oxygen deprivation,
       nutrient loading and the doubling rate . . . I
       doubted many watermen understood the full
       threat of their quiet and insidious workings.
       Perhaps it was easier to put it the way they do.
       You look hard at the water and sometimes it
       seems like it’s getting a little old and tired, a
       little messy. Simple as that, if anyone cares to
       notice.

William W. Warner, Beautiful Swimmers: Watermen, Crabs
and the Chesapeake Bay 273–74 (1976).1

1
  Warner wrote in the afterword to the 1994 edition of his
book, “There is . . . no doubt that the Bay’s natural resources
have seriously eroded since” Beautiful Swimmers was first
published.    William W. Warner, Beautiful Swimmers:
Watermen, Crabs and the Chesapeake Bay 293 (1994).




                              16
      B.     The Clean Water Act, 1972

       Congress took official note that the waters of the
United States, including the Bay, needed protection and
rescue. In 1972, it passed major revisions to federal water
pollution legislation known as the Clean Water Act. Under
that law, the EPA and the states participate in a “cooperative
federalism” framework working together to clean the
Nation’s waters.

        We deal primarily with one provision of this complex
statute, which calls for the establishment of a “total maximum
daily load” of pollution for certain waters. 33 U.S.C.
§ 1313(d)(1)(C).2 The parties dispute what those words
mean. They are not defined in the Act, but the EPA has
interpreted them to require publication of a comprehensive
framework for pollution reduction in a given body of water.
When we discuss this comprehensive document, we refer to it
by the acronym “TMDL”; by contrast, when we analyze the
statutory text, we refer to the words “total maximum daily
load.”

       The Act provides that states set a total maximum daily
load, and the EPA approves or disapproves it. If the EPA
disapproves, it must create the TMDL itself. In this case, the
Chesapeake Bay watershed jurisdictions agreed that they

2
  As in many areas of the law, specialized practitioners refer
to the uncodified sections of provisions in the Statutes at
Large. The parties thus, for example, cite the Clean Water
Act § 303(d)(1)(C) as the total maximum daily load
provision. Unless otherwise noted, we cite the law by
reference to the U.S. Code, as we find those volumes easier to
navigate than the Statutes at Large.




                             17
would not submit TMDLs, and the EPA would do so in the
first instance.

        To understand the parties’ arguments, we consider the
statutory context in which the words “total maximum daily
load” arise. The Clean Water Act does not simply direct the
publication of the TMDL; it is one step in a process with
several layers, each placing primary responsibility for
pollution controls in state hands with “backstop authority”
vested in the EPA. TMDLs happen after a state enacts
pursuant to its law (but required by the Clean Water Act)
“water quality standards.” The state designates a use for each
relevant water (e.g., recreation or fishing) and sets a target
water quality based on that use. Id. § (c)(1) & (2). The EPA
must approve or disapprove the water quality standards. If
the latter, it must promulgate its own water quality standard
for the state. 33 U.S.C. § 1313(a)(3)(A)–(C) & (b).

       Once water quality standards are in effect, the EPA
and the states share responsibility for making sure that
pollutants discharged into waters do not violate those
standards. Under the legislative and regulatory system for
cleaning our Nation’s waters, pollution comes from “point”
and “nonpoint” sources. The former are discrete places
where pollutants are discharged, like a drainpipe at a
wastewater treatment plant, while the latter are diffuse
sources of pollution, like farms or roadways, from which
runoff drains into a watershed.

       The Clean Water Act gives the EPA primary
responsibility for regulating point sources by establishing
“effluent limitations,” 33 U.SC. § 1311(b)(1)(A), which are
pollution caps that by statutory definition apply only to point
sources. Id. § 1362(11). States in turn regulate nonpoint
sources. There is significant input and oversight from the




                              18
EPA, but it does not regulate nonpoint sources directly. Id.
§ 1329(b) & (e).

       Section 1313 anticipates that effluent limitations on
point sources will be the front line of the defense against
water pollution. But, acknowledging that effluent limitations
may not be enough, § 1313(d) requires the states to submit to
the EPA a list of all bodies of water (or, by regulation, any
segment of a body of water) for which effluent limitations
and technology-based point source controls are insufficient to
meet the applicable water quality standard. These areas are
known as “water quality limited segment[s],” 40 C.F.R.
§ 131.3(h), and the list on which they appear often goes by
the “Section 303(d) list” after the part of the uncodified Clean
Water Act to which 33 U.S.C. § 1313(d) corresponds.

       Together with the Section 303(d) list, states must
submit “total maximum daily loads” for those pollutants that
cannot be brought to an acceptable level by point source
controls. 33 U.S.C. § 1313(d)(1)(A) & (C). After a state
submits its Section 303(d) list and TMDL, the EPA must
approve or disapprove them; if it disapproves, it must create
its own list and TMDL. 33 U.S.C. § 1313(d)(2).

        To recap: states set water quality standards for the
waters within their borders, and they must submit to the EPA
a list of those waters for which point-source pollution
limitations alone are not enough to make the water meet the
applicable quality standard; for all the waters on that list, a
state must submit a TMDL. If the EPA disapproves a state
submission, it takes responsibility for the unmet
requirement(s). As noted, for the Chesapeake Bay the
relevant states and the EPA agreed that the EPA would draft
the TMDL in the first instance.




                              19
      This case primarily concerns the meaning of “total
maximum daily load,” words that occur in the part of the
Clean Water Act that requires states (or, in this case, the
EPA) to:

      establish . . . the total maximum daily load[] for
      those pollutants which the Administrator
      identifies under section 1314(a)(2) of this title as
      suitable for such calculation. Such load shall be
      established at a level necessary to implement the
      applicable water quality standards with seasonal
      variations and a margin of safety which takes
      into account any lack of knowledge concerning
      the relationship between effluent limitations and
      water quality.

33 U.S.C. § 1313(d)(1)(C). The Act directed states to include
“total maximum daily load[s]” in their required “continuing
planning process[es]” no later than February 15, 1973. 33
U.S.C. § 1313(e)(2).

      C.     Definition and Development of TMDLs, 1972–
             2000
       This deadline, it turns out, was overly optimistic, as
both states and the EPA have been slow in establishing
TMDLs. See Oliver A. Houck, TMDLs, Are We There Yet?:
The Long Road Toward Water Quality–Based Regulation
under the Clean Water Act, 27 Envtl. L. Rep. (Envtl. L. Inst.)
10,391, 10,392–93 (1997). The initial blame cannot be laid
on the states because the statute explicitly requires “the
Administrator” of the EPA to identify the pollutants to which
the TMDL requirement would apply.                  33 U.S.C.
§ 1313(d)(1)(C). In 1975 the EPA issued a regulation to
define “total maximum daily load,” but even then “the
Agency still had not identified those pollutants that would be




                              20
subject to TMDL development.” Dianne K. Conway, TMDL
Litigation: So Now What?, 17 Va. Envtl. L.J. 83, 98 (1997).
It did so in 1978 and required states to submit TMDLs by
June 1979.

        The EPA’s regulations define “total maximum daily
load” as the sum of “waste load allocations” and “load
allocations.” 40 C.F.R. § 130.2(i). Also by regulatory
definition, waste load allocations are pollutant loads that
come from point sources; load allocations come from
nonpoint sources. 40 C.F.R. § 130.2(g) & (h).3 The EPA
applies these allocations to any pollutant that brings a body of
water below an acceptable standard of cleanliness. See 43
Fed. Reg. 60,662 (Dec. 28, 1978) (identifying “all pollutants”
as suitable for TMDL development).

        Once the EPA had laid out the required contents of
TMDLs, it and the states remained tardy in establishing them.
As a result, a wave of citizen-suits in the 1980s led to a
consensus that a state’s failure to submit a TMDL should be
deemed a “constructive submission” that no TMDL is needed,
triggering the EPA’s duty to accept that conclusion or
promulgate its own TMDL. Kingman Park Civic Ass’n v.
EPA, 84 F. Supp. 2d 1, 5 (D.D.C. 1999) (collecting cases).
Even these successes did not spur immediate action, as courts
initially would not follow the “constructive submission”
theory “in cases brought against states which engaged in
some level of TMDL activity, no matter how minute.”
Conway, TMDL Litigation, 17 Va. Envtl. L.J. at 95.

      In the mid-1990s, nearly a quarter century past the
Clean Water Act’s “deadline,” courts became frustrated with

3
 In the initial regulation defining TMDLs, the terms were
different, but the EPA still required allocation between point
and nonpoint sources. 40 Fed. Reg. 55,346 (Nov. 28, 1975).




                              21
the prevailing “wait-and-see” approach and directed states
and the EPA to develop TMDLs with more dispatch. See
Sierra Club v. Hankinson, 939 F. Supp. 865 (N.D. Ga. 1996),
939 F. Supp. 872 (N.D. Ga. 1996); Idaho Sportsmen’s
Coalition v. Browner, 951 F. Supp. 962 (W.D. Wash. 1996).
Following the success of these cases, “citizen-plaintiffs,
imbued with the ecosystem consciousness, launched a tidal
wave of lawsuits to force the EPA and the states to implement
the TMDLs process.” Michael M. Wenig, How “Total” Are
“Total Maximum Daily Loads”?—Legal Issues Regarding
the Scope of Watershed-Based Pollution Control Under the
Clean Water Act, 12 Tul. Envtl. L.J. 87, 94 (1998).

       The lawsuits of the 1990s were followed by the actual
drafting of thousands of TMDLs, which the EPA has
described as “the technical backbone” of its approach to
cleaning the Nation’s waters. EPA Office of Water, Total
Maximum Daily Load (TMDL) Program Draft TMDL
Program Implementation Strategy § 1.2 (1996). TMDLs are
now thorough “informational tools that allow the states to
proceed from the identification of waters requiring additional
planning to the required plans.” Pronsolino v. Nastri, 291
F.3d 1123, 1129 (9th Cir. 2002). TMDLs are not self-
executing, but they serve as the cornerstones for pollution-
reduction plans that do create enforceable rights and
obligations.4


4
   The parties debate what precisely TMDLs are. Our
understanding of them as informational tools is supported by
every case and piece of scholarship to consider them as well
as the language of the Chesapeake Bay TMDL itself. See
City of Arcadia v. EPA, 411 F.3d 1103, 1105 (9th Cir. 2005);
Sierra Club v. Meiburg, 296 F.3d 1021, 1025 (11th Cir. 2002)
(“Each TMDL serves as the goal for the level of that pollutant




                             22
      D.     The Chesapeake Bay TMDL, 2000–2010

       Development of the Chesapeake Bay TMDL began in
earnest with the Chesapeake 2000 Agreement, whereby the
EPA and political backers from the Bay states made
commitments geared to reducing pollution in the Bay. This
Agreement eventually gave way to states’ submission to the
EPA of “Phase I Watershed Improvement Plans,” which were
drafts proposing target pollutant limitations and how the

in the waterbody to which that TMDL applies.”); Bravos v.
Green, 306 F. Supp. 2d 48, 56 (D.D.C. 2004) (“EPA’s
approval of a State’s TMDL does not translate into approval
of the State’s implementation plan.”); City of Arcadia v. EPA,
265 F. Supp. 2d 1142, 1144 (N.D. Cal. 2003) (“TMDLs
established under Section 303(d)(1) of the CWA function
primarily as planning devices and are not self-executing.”);
Idaho Sportsmen’s Coal. v. Browner, 951 F. Supp. 962, 966
(W.D. Wash. 1996) (“TMDL development in itself does not
reduce pollution. It is only a step toward bringing [water
quality limited segments] into compliance with water quality
standards; TMDLs inform the design and implementation of
pollution control measures.”); Corey Longhurst, Where Is the
Point? Water Quality Trading’s Inability to Deal with
Nonpoint Source Agricultural Pollution, 17 Drake J. Agric. L.
175, 187 (2012); Jan G. Laitos & Heidi Ruckriegle, The
Clean Water Act and the Challenge of Agricultural Pollution,
37 Vt. L. Rev. 1033, 1054–57 (2013) (criticizing courts for
the limited legal effect they have given to TMDLs); J.A. 1113
(“The cornerstone of the accountability framework is the
jurisdictions’ development of [Watershed Improvement
Plans], which serve as roadmaps for how and when a
jurisdiction plans to meet its pollutant allocations under the
TMDL.”).




                             23
states would achieve them.          The EPA developed the
Chesapeake Bay TMDL in reliance on these plans and did so
only after approving the pollutant limitations and concluding
that each state had given “reasonable assurance” of actually
meeting the targets in its Watershed Improvement Plan.
Several of the first drafts of the Phase I Watershed
Improvement Plans did not provide reasonable assurance,
whereupon the EPA conferred with the relevant jurisdictions,
they revised their Plans, and the EPA incorporated those
revisions. It determined that the final draft Phase I Watershed
Improvement Plans provided reasonable assurance in all
respects save two sources of pollution (Pennsylvania urban
stormwater and West Virginia agriculture), and it imposed a
“backstop adjustment,” meaning that it will require greater
reductions from point sources in Pennsylvania and West
Virginia if those states cannot meet their projected load
allocations. The EPA also decided to provide a “backstop
allocation” for New York because that jurisdiction proposed
to discharge too much nitrogen and phosphorous; this will
also require more stringent point-source limitations than New
York proposed.

        After making these adjustments to the states’
Watershed Improvement Plans, the EPA incorporated them
into the final Chesapeake Bay TMDL. It is detailed, as it
includes point- and nonpoint-source limitations on nitrogen,
phosphorous, and sediment for 92 segments of the Bay
identified as overpolluted and further allocates those limits to
specific point sources and to nonpoint source sectors. The
TMDL sets target dates, anticipating that 60% of its proposed
actions will be complete by 2017, with all pollution control
measures in place by 2025. The next step, yet to happen, is
for the states to develop their Phase II Watershed
Improvement Plans to implement the TMDL.




                              24
       On December 29, 2010, the EPA promulgated the
TMDL through the notice-and-comment rulemaking process
of the Administrative Procedure Act (“APA”). See 5 U.S.C.
§ 553. Over 45 days, the EPA held 18 public meetings (at
which 2,500 members of the public attended), and it received
more than 14,000 comments. It took these comments and
meetings into account when publishing the final TMDL.

       E.     Procedural Background, 2011–Present

       As discussed above, TMDLs have long been the
subject of litigation. Environmental groups continue to press
the EPA to promulgate more stringent TMDLs. E.g., Ctr. For
Biological Diversity v. EPA, No. 13-cv-1866, 2015 WL
918686 (W.D. Wash. Mar. 2, 2015). Not to be left on the
sidelines, commercial concerns took to the courts to air their
grievances with the EPA—this time not for acting too slowly,
but for acting at all. Our case is of this most recent variety.

       In January 2011, Farm Bureau sued the EPA under the
APA and the citizen-suit provision of the Clean Water Act. It
asserted that the EPA exceeded its statutory authority by
including deadlines and allocations in the TMDL and by
requiring “reasonable assurance” from the states in drafting
that document.      The District Court granted summary
judgment in favor of the EPA, and this appeal followed.

III.   Jurisdiction

       The District Court had jurisdiction under 5 U.S.C.
§ 702 and 28 U.S.C. § 1331. We have jurisdiction pursuant
to 28 U.S.C. § 1291, and our standard of review is de novo.
Pastore v. Bell Tel. Co. of Pennsylvania, 24 F.3d 508, 511 (3d
Cir. 1994).




                              25
        The TMDL is yet unenforced against anyone, nor can
it be until it is implemented as part of a state’s continuing
planning process for managing water pollution, 33 U.S.C.
§ 1313(e). Thus, Farm Bureau’s standing to challenge the
TMDL and the ripeness of this dispute are open to debate.
The EPA does not challenge Farm Bureau’s standing on
appeal, but we have a free-standing duty to determine our
jurisdiction.

       A.     Standing

        “To ensure the proper adversarial presentation, . . . a
litigant must demonstrate that it has suffered a concrete and
particularized injury that is either actual or imminent, that the
injury is fairly traceable to the defendant, and that it is likely
that a favorable decision will redress that injury.”
Massachusetts v. EPA, 549 U.S. 497, 517 (2007) (emphases
added). The injury claimed by members of the trade
associations comprising Farm Bureau is the certainty that
they will incur compliance costs when the TMDL is
implemented and enforcement mechanisms are put in place.
Thus, even if the TMDL does not cause injury by itself, it will
give way to requirements with which Farm Bureau will have
to comply. See 33 U.S.C. § 1313(e) (mandating TMDL’s
incorporation into states’ “continuing planning process[es]”).
Specifically, states’ continuing planning processes will, by
operation of the Clean Water Act, impose on the sectors in
which Farm Bureau operates more stringent nonpoint source
pollutant limitations than currently in place. See TMDL
Appendix R.         These requirements will in turn cause
compliance costs for Farm Bureau, a classic injury-in-fact.
Danvers Motor Co. v. Ford Motor Co., 432 F.3d 286, 291 (3d
Cir. 2005) (“While it is difficult to reduce injury-in-fact to a
simple formula, economic injury is one of its paradigmatic
forms.”).




                               26
       Although there is a plausible argument that Farm
Bureau’s injury is insufficiently particularized and too
speculative, as we do not know precisely what form new
regulations will take, it is akin to injuries the Supreme Court
has found sufficient for standing. Ass’n of Data Processing
Serv. Organizations, Inc. v. Camp, 397 U.S. 150, 152 (1970)
(data processors have standing when regulation expanded
number of institutions authorized to perform data processing,
thus increasing competition in the field); Barlow v. Collins,
397 U.S. 159, 164 (1970) (tenant-farmers had standing when
new regulation effectively gave incentives to landlords to
charge higher rents). In general, regulated entities that assert
likely economic injury have standing even before the
challenged regulatory action fully takes effect. See Sierra
Club v. Morton, 405 U.S. 727, 733–34 (1972) (“[P]alpable
economic injuries have long been recognized as sufficient to
lay the basis for standing, with or without a specific statutory
provision for judicial review.”)

       Fair traceability and redressability are easily met here.
There is no doubt that the EPA promulgated the TMDL, and
removing the parts to which Farm Bureau objects would
substantially lighten its regulatory burden.

       B.     Ripeness

       Similarly, a pre-enforcement challenge to a regulation
is ripe where the issues presented are fit for judicial review
and hardship to the parties would result without hearing the
suit. Abbott Labs. v. Gardner, 387 U.S. 136, 149 (1967).
Here the parties present a purely legal dispute on a well-
developed record about the EPA’s process of promulgating a
TMDL. Although the TMDL has yet to be incorporated into
a state’s continuing planning process and enforced against
any individual plaintiff, members of the trade associations
will have reason to limit their discharge of pollutants in




                              27
anticipation of the TMDL’s implementation. And it would
impose hardship on the EPA and the states not to hear this
dispute now because they are poised to spend more time,
energy, and money in developing an implementation plan. If
there is something wrong with the TMDL, it is better to know
now than later.

      As we have jurisdiction and the case is ripe, we
proceed to the merits.

IV.   Merits

        Farm Bureau interprets the words “total maximum
daily load” in the Clean Water Act, codified at 33 U.S.C.
§ 1313(d)(1)(C), as unambiguous: a TMDL can consist only
of a number representing the amount of a pollutant that can be
discharged into a particular segment of water and nothing
more. Thus it argues that the EPA overstepped its statutory
authority in drafting the Chesapeake Bay TMDL when the
agency (1) included in the TMDL allocations of permissible
levels of nitrogen, phosphorous, and sediment among
different kinds of sources of these pollutants, (2) promulgated
target dates for reducing discharges to the level the TMDL
envisions, and (3) obtained assurance from the seven affected
states that they would fulfill the TMDL’s objectives. In Farm
Bureau’s view, even if allocations, target dates, and
reasonable assurance are useful in calculating the number that
is the TMDL, the final document may not specify a
distribution of pollutants from point and nonpoint sources or
deadlines for meeting the target reductions in pollutant
discharge, nor may the EPA in drafting the document obtain
any assurance from states that they will meet the targets.




                              28
      A.      Framework for our Decision

       The parties agree that this case is governed by Chevron
v. NRDC, 467 U.S. 837 (1984). The mechanics of Chevron
are familiar: at “Step One,” courts inquire “whether Congress
has directly spoken to the precise question at issue. 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.
In framing “the precise question at issue,” we ask “whether
the statute unambiguously forbids the Agency’s
interpretation.” Barnhart v. Walton, 535 U.S. 212, 217–18
(2002).       When the intent of Congress is expressed
ambiguously in some way relevant to the case at hand, courts
proceed to “Step Two.” There the agency’s interpretations
“are given controlling weight unless they are arbitrary,
capricious, or manifestly contrary to the statute.” Chevron,
467 U.S. at 844.
        Underlying Chevron’s framework is courts’
understanding that Congress sometimes uses ambiguous
language to delegate a scope of authority (or a gap to fill) to
an administrative agency charged with administering the
ambiguous statute. This has not always been clear, as
Chevron itself offered a variety of justifications for its
outcome, but “the [Supreme] Court over the last decade,
beginning in United States v. Mead Corp., [533 U.S. 218
(2001)], has explicitly re-grounded Chevron in congressional
intent,” specifically, “intent to delegate.” Abbe R. Gluck,
What 30 Years of Chevron Teach Us About the Rest of
Statutory Interpretation, 83 Fordham L. Rev. 607, 610 & n.7
(2014) (footnotes omitted); Mead, 533 U.S. at 226–27
(“[A]dministrative implementation of a particular statutory
provision qualifies for Chevron deference when it appears
that Congress delegated authority to the agency generally to
make rules carrying the force of law, and that the agency




                              29
interpretation claiming deference was promulgated in the
exercise of that authority.”). Four years after Mead, the
Supreme Court reaffirmed and made more explicit that
Chevron deference recognizes Congress’s intent to delegate
gap-filling power to agencies. National Cable & Telecomms.
Ass’n v. Brand X Internet Services, 545 U.S. 967, 980 (2005)
(“Chevron . . . held that ambiguities in statutes within an
agency’s jurisdiction to administer are delegations of
authority to the agency to fill the statutory gap in reasonable
fashion.”); see also Peter L. Strauss, “Deference” Is Too
Confusing—Let’s Call Them “Chevron Space” and
“Skidmore Weight,” 112 Colum. L. Rev. 1143, 1145 (2012)
(“‘Chevron space’ denotes the area within which an
administrative agency has been statutorily empowered to act
in a manner that creates legal obligations or constraints—that
is, its delegated or allocated authority.”).

       Whether an interpretation falls within the scope of
authority that Congress has delegated is for the courts to
decide at Step One because “[t]he fact that Congress has left a
gap for the agency to fill means that courts should defer to the
agency’s reasonable gap-filling decisions, not that courts
should cease to mark the bounds of delegated agency choice.”
Negusie v. Holder, 555 U.S. 511, 531 (2009) (Stevens, J.,
concurring in part and dissenting in part); see also Util. Air
Regulatory Grp. v. EPA, 134 S. Ct. 2427, 2442 (2014) (“Even
under Chevron’s deferential framework, agencies must
operate within the bounds of reasonable interpretation.”
(internal quotation marks omitted)); MCI Telecomms. Corp.
v. Am. Tel. & Tel. Co., 512 U.S. 218, 229 (1994) (“[A]n
agency’s interpretation of a statute is not entitled to deference
when it goes beyond the meaning that the statute can bear.”);
Peter L. Strauss et al., Gellhorn & Byse’s Administrative Law
1073 (11th ed. 2011) (“Chevron said that within the possible
meanings of a statute, a reviewing court should accept any
reasonable meaning given by the agency. As the MCI case




                               30
[which never reached Step Two, 512 U.S. at 229] emphasizes,
what the reasonable meanings might be is, within the
Chevron universe, a question for the courts to decide.”).

       When the agency interpretation faithfully fills the gap
that Congress created, we move to Step Two, where we do
not ask whether it is the best possible interpretation of
Congress’s ambiguous language.          Instead, we extend
considerable deference to the agency and inquire only
whether it made “a reasonable policy choice” in reaching its
interpretation. Brand X, 545 U.S. at 986.

      With the above framework in mind, we proceed to
Step One.

      B.      Chevron Step One

       To repeat, before us is whether in calculating and
expressing a “total maximum daily load,” 33 U.S.C.
§ 1313(d)(1)(C), the EPA may include (1) allocations of
pollution levels among different kinds of sources, (2) a
timeframe for complying with the TMDL’s requirements, and
(3) assurance from the states that will implement the TMDL.
Farm Bureau concludes that the statute unambiguously
forecloses the EPA’s interpretation and hence the agency is
not entitled to deference. Several considerations persuade us
otherwise.

               1.    Case Law on TMDLs

       The District Court noted that it was a question of first
impression whether a TMDL could include more than a
quantity of a pollutant. Am. Farm Bureau Fed’n v. EPA, 984
F. Supp. 2d 289, 316–18 (M.D. Pa. 2013). Since its decision,
there has been no development in the case law on that point.
However, we do not write on a completely blank slate. As




                              31
the District Court also observed, many circuit and district
courts have defined TMDLs to accord with the EPA’s
regulations (implying they did not present a problem). E.g.,
Upper Blackstone Water Pollution Abatement Dist. v. EPA,
690 F.3d 9, 14 n.8 (1st Cir. 2012); Thomas v. Jackson, 581
F.3d 658, 662 (8th Cir. 2009); Friends of Earth v. EPA, 333
F.3d 184, 186 n.5 (D.C. Cir. 2003); Sierra Club v. Meiburg,
296 F.3d 1021, 1025 (11th Cir. 2002); Hayes v. Whitman,
264 F.3d 1017, 1021 n.2 (10th Cir. 2001);
Dioxin/Organochlorine Ctr. v. Clarke, 57 F.3d 1517, 1520
(9th Cir. 1995). If Farm Bureau were correct that the statute
unambiguously supports its reading, we would expect one of
the judges who has presided over TMDL litigation to have
noticed the disconnect between the statute and the regulation,
but there has been none.

        Additionally, in response to challenges from both
environmental and industry groups, courts have recognized
the EPA’s authority to fill the Clean Water Act’s considerable
gaps on how to promulgate a “total maximum daily load.”
Pronsolino, 291 F.3d at 1131 (“[T]he EPA has the delegated
authority to enact regulations carrying the force of law
regarding the identification of § 303(d)(1) waters and
TMDLs.”); NRDC v. Muszynski, 268 F.3d 91, 98–99 (2d Cir.
2001) (“We are not prepared to say Congress intended that
such far-ranging agency expertise be narrowly confined in
application to regulation of pollutant loads on a strictly daily
basis. . . . Accordingly, we agree with [the] EPA that a ‘total
maximum daily load’ may be expressed by another measure
of mass per time.”); Anacostia Riverkeeper, Inc. v. Jackson,
798 F. Supp. 2d 210, 245 (D.D.C. 2011) (“[T]he [Clean
Water Act]’s references to water quality standards require
only that a TMDL set load levels ‘necessary to attain and
maintain applicable water quality standards,’ 33 U.S.C. §
1313(d)(1)(C), and do[] not otherwise refer to any particular
timeframe. . . . In light of the CWA’s silence on whether




                              32
applicable criteria must be achieved at all times or may be
periodically violated, the Court looks to whether [the] EPA
has reasonably resolved the issue.”).

       The only time a court has considered an aspect of the
phrase “total maximum daily load” unambiguous was in
response to a challenge to the EPA’s practice of promulgating
total maximum seasonal or annual loads. The D.C. Circuit
held that the word “daily” was unambiguous, though it did
not consider the above phrase unambiguous in all respects.
Friends of Earth, Inc. v. EPA, 446 F.3d 140, 144 (D.C. Cir.
2006). The Second Circuit disagrees with the D.C. Circuit on
this point, Muszynski, 268 F.3d at 98–99, and even after
Friends of Earth the District of D.C. has allowed the EPA to
issue total maximum annual or seasonal loads in addition to
daily loads because, although the statute is explicit about the
requirement for a daily load, it is silent on whether another
timeframe may be used when that would be more appropriate
for the particular pollutant at issue. Anacostia Riverkeeper,
798 F. Supp. 2d at 245.

        Turning from the specific statutory language in this
case, the Supreme Court has held that Chevron deference is
appropriate where an agency is charged with administering a
complex statutory scheme requiring technical or scientific
sophistication. Brand X, 545 U.S. at 1002–03; Nat’l Cable &
Telecomms. Ass’n, Inc. v. Gulf Power Co., 534 U.S. 327, 339
(2002) (“As it was in Chevron, the subject matter here is
technical, complex, and dynamic. . . .” (citation omitted)).
There is no doubt that the Clean Water Act falls into this
category of legislation. See, e.g., United States v. Riverside
Bayview Homes, Inc., 474 U.S. 121, 132–33 (1985) (“[The
Act] constituted a comprehensive legislative attempt to
restore and maintain the chemical, physical, and biological
integrity of the Nation’s waters. This objective incorporated
a broad, systemic view of the goal of maintaining and




                              33
improving water quality.” (internal quotation marks and
citation omitted)). Moreover, Congress’s delegations to the
EPA under the Clean Water Act are not limited to occasional
ambiguous words; instead, Congress granted broad regulatory
authority to the EPA, charging that, “[e]xcept as otherwise
expressly provided in this chapter, the Administrator of the
[EPA] . . . shall administer this chapter.” 33 U.S.C. §
1251(d).

       Mindful of agencies’ considerable power under
complex statutory regimes like the Clean Water Act, coupled
with courts’ consistent determinations that “total maximum
daily load” is ambiguous (except—though there is a split of
authority on the point—the word “daily”) and the fact that no
court has adverted to any problem with the EPA’s regulatory
interpretation of the phrase, we turn to the text of the TMDL
provision.

              2.     Statutory Text
       Farm Bureau’s strongest argument is that Congress
specifically authorized the EPA to publish “total maximum
daily load[s] . . . at a level necessary to implement the
applicable water quality standards . . . .”          33 U.S.C.
§ 1313(d)(1)(C) (emphases added). Under Farm Bureau’s
reading, a “total load” is just a number, like the “total” at the
bottom of a restaurant receipt. This ordinary understanding
of the word “total” is supported, the argument continues,
because the load is to be established at a “level,” which can
be high or low (so long as it is necessary to implement the
water quality standards); in any event it should not be
expressed as a comprehensive framework, and in no event
can a TMDL include allocations among point and nonpoint
sources, deadlines, and the reasonable assurance requirement.




                               34
         This argument has some intuitive appeal, but other
readings are possible. Our most significant textual concern is
that Farm Bureau’s analysis makes the word “total”
redundant. “Maximum daily load[s] . . . . established at a
level necessary to implement the applicable water standard”
would mean the same thing that Farm Bureau argues “total
maximum daily load” means: a number set at a level needed
to alleviate water pollution. Applying the canon against
surplusage, a plausible understanding of “total” is that it
means the sum of the constituent parts of the load. The load
is still set at the level necessary to fight pollutants, but it is
expressed in terms of a total of the different relevant
allocations.

        Other uses of “total” in the Clean Water Act support
this reading. For example, in a section relating to the EPA’s
power to grant funds to publicly owned treatment works, the
agency must consider “the total cost of operation and
maintenance of such works by each user class (taking into
account total waste water loading of such works, the
constituent elements of the wastes, and other appropriate
factors).”     33 U.S.C. § 1284(b)(1) (emphasis added).
Admittedly, the explicit listings of factors in calculating the
“total cost” under § 1284 distinguishes that use of “total”
from the language in § 1313, yet it indicates that Congress
does use the word to mean something more than a single
number. See also id. § 1284(b)(4) (requiring “applicant to
establish a procedure under which the residential user will be
notified as to that portion of his total payment which will be
allocated to the cost of the waste treatment services.”
(emphases added)). Another law relating to our Nation’s
waters requires the EPA to consider “the total quantity of
commerce supported by” a given body of water. Id.
§ 2238(d)(1)(C)(i)     (Water     Resources     Reform     and
Development Act of 2014, P.L. 113-121 § 2102). It is
unclear how “commerce” can be expressed as a number, and




                               35
we surmise that “total” in that context allows the EPA to
consider and express a complex mix of activities that affect
its judgment.

        Additionally, although Congress explicitly required the
EPA to establish “total maximum daily loads,” it nowhere
prescribed how the EPA is to do so. The agency has chosen
to lay out in detail (1) how and why it arrived at the number it
chose; (2) how it thinks it and affected jurisdictions will be
able to achieve that number; (3) why that number is
“necessary to implement the applicable water quality
standard[],” id. § 1313(d)(1)(C); (4) when it expects the
TMDL to achieve the applicable water quality standard; and
(5) what it will do if the water quality standard is not met. As
the EPA has chosen to use notice-and-comment rulemaking
to promulgate TMDLs, the APA likely requires the EPA to
provide sufficient information in connection with the TMDL
for the public adequately to comment on the agency’s
judgment and to make suggestions where appropriate.
Cement Kiln Recycling Coal. v. EPA, 493 F.3d 207, 225
(D.C. Cir. 2007) (“A notice of proposed rulemaking must
provide sufficient factual detail and rationale for the rule to
permit interested parties to comment meaningfully.” (internal
quotation marks and citations omitted)). The EPA would fall
afoul of this requirement if it published only a number with
no supporting information, as the public would be unable to
comment on the number without knowing whether or how the
EPA thought such a level of discharged pollutant could be
achieved.

        The EPA’s approach also fits the statute’s requirement
that the load be established in light of “seasonal variations
and a margin of safety which takes into account any lack of
knowledge concerning the relationship between effluent
limitations and water quality.” 33 U.S.C. § 1313(d)(1)(C).
Under Farm Bureau’s approach, these factors that affect the




                              36
EPA’s calculation would need to remain absent from the
TMDL. It would be strange to require the EPA to take into
account these specific considerations but at the same time
command the agency to excise them from its final product. If
anything, the requirements that the TMDL (1) be established
at a level necessary to implement water quality standards,
with (2) seasonal variations, and (3) a margin of safety that
takes into account (4) any lack of knowledge concerning the
relationship between effluent limitations and water quality,
taken together, tend to suggest that “total maximum daily
load” is a term of art meant to be fleshed out by regulation,
and certainly something more than a number.

       Farm Bureau’s textual argument at Step One fails to
persuade us that Congress excluded everything other than the
sum of pollutants from a TMDL. Congress was ambiguous
on the content of the words “total maximum daily load”: they
are not defined in the statute, and “total” is susceptible to
multiple interpretations. Furthermore, the Clean Water Act
includes certain substantive requirements that expand the
scope of a TMDL beyond a mere number. It is silent on how
the EPA must set the loads, and the APA requires the EPA to
provide information about how it arrived at its conclusion.
These factors suggest that Congress wanted an expert to give
meaning to the words it chose, and, as we explain below, we
believe the EPA’s interpretation falls within the gap created
by Congress.

              3.     Statutory Structure and Purpose

        Turning from the text of the provision, we consider the
structure and purpose of the Clean Water Act. Broadly
speaking, it “anticipates a partnership between the States and
the Federal Government, animated by a shared objective: ‘to
restore and maintain the chemical, physical, and biological
integrity of the Nation’s waters.’ 33 U.S.C. § 1251(a).”




                              37
Arkansas v. Oklahoma, 503 U.S. 91, 101 (1992). This goal
informs our understanding that “total maximum daily load” is
broad enough to include allocations, target dates, and
reasonable assurance.

                     i.     Allocations Between Point and
                            Nonpoint Sources

       As noted, the Act assigns the primary responsibility for
regulating point sources to the EPA and nonpoint sources to
the states. The EPA sets limits on pollution that may come
from point sources via a permitting process (which can be
delegated to the states) known as the National Pollutant
Discharge Elimination System.           33 U.S.C. § 1342.
Nonetheless, in drafting a TMDL the Clean Water Act
unambiguously requires the author (here, the EPA) to take
into account nonpoint sources (though whether those sources
must be expressed is not obvious). This conclusion follows
when we consider the steps that precede and culminate in a
TMDL.

       1.     Each state5 must designate a use for each body
of water within its borders and set a target water quality based
on that use. 33 U.S.C. § 1313 (c)(1) & (2). The state must
then enact “water quality standards” pursuant to state law. Id.
§ 1313(a) & (b).

        2.    In order to meet water quality standards, the
EPA (or the states to which the EPA has delegated this
responsibility) sets “effluent limitations,” which are pollution
limits on point sources. Id. §§ 1311(b)(1)(A) & 1362(11).



5
  If a state does not comply with any of the requirements
outlined in this list, responsibility shifts to the EPA.




                              38
        3.    States must submit to the EPA a list of the
waters within their boundaries for which effluent limitations
(a.k.a. point-source pollution limits) are, by themselves,
inadequate to attain the applicable water quality standard—
i.e., those waters for which both point source and nonpoint
source limitations will be necessary. Id. § 1313(d).

      4.      It is only for these waters, for which point
source effluent limitations alone are insufficient, that a state
must establish a TMDL.

       5.     TMDLs set the maximum amount of pollution a
water body can absorb before violating applicable water
quality standards. In the statutory context noted above, it is
impossible to meet those standards by point-source reductions
alone. Therefore, the Clean Water Act requires the drafter of
a TMDL to consider nonpoint-source pollution.

       “As should be apparent, TMDLs are central to the
Clean Water Act’s water-quality scheme because . . . they tie
together point-source and nonpoint-source pollution issues in
a manner that addresses the whole health of the water.”
Meiburg, 296 F.3d at 1025 (internal quotation marks
omitted). As far as allocations are concerned, the EPA’s
construction of the TMDL requirement comports well with
the Clean Water Act’s structure and purpose. Specifically
allocating the pollution load between point sources (primarily
the EPA’s responsibility) and nonpoint sources (the states’
dominion) is a commonsense first step to achieve the target
water quality. See Wenig, How “Total,” 12 Tul. Envtl. L.J.
at 150 (“Ideally, all ecosystem harms should be subject to
numerical loading and allocation calculations to maximize
TMDLs’ value of providing the ‘technical backbone’ or
‘blueprint’ for a watershed approach.”).




                              39
        Because TMDLs only relate to bodies of water for
which point source limitations are insufficient, they must take
into account pollution from both point and nonpoint sources.
We believe the congressional silence on how to promulgate a
TMDL and the congressional command that a TMDL be
established only for waters that cannot be cleaned by point-
source limitations alone (necessarily implying that, whatever
form the TMDL takes, it must incorporate nonpoint source
limitations) combine to authorize the EPA to express load and
waste load allocations. To be sure, the statute does not
command the EPA’s final regulation to allocate explicitly
parts of a load among different kinds of sources, but we agree
with the EPA that it may do so.

                     ii.   “Deadlines” or “Target Dates”

        Similarly, it is common sense that a timeline
complements the Clean Water Act’s requirement that all
impaired waters achieve applicable water quality standards.
The amount of acceptable pollution in a body of water is
necessarily tied to the date at which the EPA and the states
believe the water should meet its quality standard; if the
target date is 100 years from now, more pollution per day will
be allowable than if the target date is five years from now.
Additionally, any meaningful pollution-reduction plan needs
to take into account the dynamic nature of watersheds,
particularly the fact that they change over time. Robert W.
Adler, Addressing Barriers to Watershed Protection, 25
Envtl. L. 973, 982 (1995) (“[R]iver systems are four-
dimensional in nature: 1) longitudinal (upstream-
downstream); 2) lateral (floodplain-uplands); 3) vertical
(groundwater-surface water); and 4) temporal (all three
spatial dimensions change over time).”). As promulgating an
accurate TMDL—that is, one that states a pollutant load
“necessary to implement the applicable water quality
standards,”      33      U.S.C.     § 1313(d)(1)(C)—requires




                              40
consideration of a timeline and of changes over time, it is
more consistent with the purpose of the Clean Water Act to
express the deadline that the EPA relied on in calculating the
TMDL than to make states and the public guess what it is.

                     iii.   Reasonable Assurance

       Farm Bureau’s argument that the Act forbids the EPA
from seeking reasonable assurance from the states that their
Watershed Improvement Plans will meet their stated goals is
also inconsistent with the purpose and structure of the Clean
Water Act. The TMDL must be set “at a level necessary to
implement the applicable water quality standards.” 33 U.S.C.
§ 1313(d)(1)(C). The EPA chose to set the TMDL with
substantial input from the states but, in order to comply with
the Clean Water Act and the APA, the EPA would not blindly
accept states’ submissions. Instead it decided to satisfy itself
that the states’ proposals would actually “implement the
applicable water quality standards.” Id. This requirement
made sure that the EPA could exercise “reasoned judgment”
in evaluating the states’ proposed standards and was thus
consistent with the Clean Water Act. Ctr. for Biological
Diversity v. EPA, 749 F.3d 1079, 1087 (D.C. Cir. 2014).

                     iv.    Summary      of    Structure    and
Purpose

       The point of the TMDL is to take into consideration
nonpoint-source pollution; no meaningful decision about
limiting pollution can be made without specifying a time
frame within which pollution is to be eliminated; and the
Clean Water Act envisions assurance of effective pollution
controls. Preventing the EPA from expressing allocations and
timelines and from obtaining reasonable assurance from
affected states appears to frustrate those goals, and thus the
phrase “total maximum daily load” has enough play in the




                              41
joints to allow the EPA to consider and express these factors
in its final action.

              4.     Avoidance Canons

       Farm Bureau counters that the Chesapeake Bay TMDL
intrudes on land use, an area traditionally regulated by states.
It contends that we should not accept the EPA’s construction
of the words “total maximum daily load” without a clear
statement that Congress intended federal involvement in this
realm of state policymaking.

       This argument requires us to consider Chevron’s
interaction with two canons of statutory construction—
constitutional avoidance and the related “federalism canon”
that “Congress does not readily interfere” with states’
“substantial sovereign powers under our constitutional
scheme.” Gregory v. Ashcroft, 501 U.S. 452, 461 (1991).

       How and even whether to apply these canons during a
Chevron analysis has been a matter of debate in both the
judiciary and academia. Rapanos v. United States, 547 U.S.
715, 737–38 (2006) (plurality opinion) (rejecting agency
interpretation that would impinge on “the States’ traditional
and primary power over land and water use”); id. at 757–58
(Roberts, C.J., concurring) (implying agency interpretation
would have been upheld had it been promulgated through
notice-and-comment rulemaking); id. at 776–77 (Kennedy, J.,
concurring in the judgment) (rejecting plurality’s “federalism
concerns”); id. at 803 (Stevens, J., dissenting) (“The two
canons of construction [federalism and constitutional
avoidance] relied on by the plurality . . . fail to overcome the
deference owed to the Corps.”); Kenneth A. Bamberger,
Normative Canons in the Review of Administrative
Policymaking, 118 Yale L.J. 64, 118 (2008) (suggesting
federalism canon could be applied at Chevron Step Two);




                              42
Scott A. Keller, How Courts Can Protect State Autonomy
from Federal Administrative Encroachment, 82 S. Cal. L.
Rev. 45, 81–91 (2008) (arguing that courts should apply the
federalism canon whenever an agency interpretation
encroaches on state autonomy); Abbe R. Gluck, Intersystemic
Statutory Interpretation: Methodology as “Law” and the Erie
Doctrine, 120 Yale L.J. 1898, 1987–89 (2011) (arguing that
Supreme Court should (but does not) give stare decisis effect
to interpretive methodologies, including federalism canon);
Strauss et al., Administrative Law 1091 (questioning
existence of federalism canon).

        We think the two interpretive canons can be used—
like all “traditional tools of statutory construction,” Chevron,
467 U.S. at 843 n.9—at the Step One stage of defining the
scope of a congressional delegation in light of an agency’s
actual interpretation. Put another way, they may be of use as
we consider whether an agency’s interpretation falls within a
gap Congress has authorized an agency to fill. We begin with
federalism.

                     i.     Federalism
        The two most factually on-point cases that consider the
federalism canon are Solid Waste Agency of N. Cook Cnty. v.
Army Corps of Eng’rs (SWANCC), 531 U.S. 159 (2001), and
Rapanos, 547 U.S. 715. In both cases, the Army Corps of
Engineers asserted the authority to regulate—i.e.,
“jurisdiction” in the administrative law sense of the word—
certain geographical areas as “waters of the United States.”
There was debate among the Supreme Court’s justices about
how wet these areas were, but for our purposes it suffices to
say that you could not float a ship on them. In those cases,
Congress’s intent to alter the traditional federal-state balance
was doubtful, as it was unclear whether the Corps even had
jurisdiction over the areas at issue. The Court in SWANCC




                              43
and a plurality in Rapanos were unwilling to accept the
Corps’ assertion of jurisdiction over what looked like places
traditionally regulated by the states.

        In our case, however, jurisdiction over the Chesapeake
Bay is not at issue. The question is far finer grained: what is
a “total maximum daily load”? Even if the consequences of
defining the terms of the statute as the EPA has done intrudes
more significantly on certain state prerogatives than Farm
Bureau’s proposal, we already know that the term “total
maximum daily load” exists within a cooperative federalism
framework and that the area being regulated is clearly within
the agency’s jurisdiction. In this context, requiring another
“clear statement” of congressional intent for every ambiguous
term in a highly technical statute, before accepting an
interpretation that could affect our federal structure, would
defeat one of the central virtues of the Chevron framework:
Congress may leave interstitial details to expert agencies and
need not think through at the drafting stage every possible
permutation of agencies’ plausible future interpretations. To
use the Supreme Court’s language disposing of a similar
argument (in a different regulatory context), the TMDL
provision “explicitly supplants state authority by requiring”
states to participate in pollution-reduction programs by, in
part, submitting a TMDL, “and the meaning of that phrase
[here, total maximum daily load] is indisputably a question of
federal law.” City of Arlington v. FCC, 133 S. Ct. 1863, 1873
(2013). Nor can we say that defining “loads” of pollution as
allocated among different sources or expressed as a single
number is a matter of regulation traditionally reserved to the
states. Thus, to the extent the TMDL may affect land-use
decisions, we do not see that as foreclosing the EPA’s
interpretation.

        Perhaps we would reach a different result if the TMDL
in fact made land-use decisions diminishing state authority in




                              44
a significant way; we might then say that Congress delegated
some authority over the definitions of technical terms in the
Clean Water Act but not so much discretion as to usurp
states’ zoning powers. Indeed, the heart of Farm Bureau’s
federalism argument is that the TMDL impermissibly grants
the EPA the authority to make land-use and zoning
regulations. The challenge is long on swagger but short on
specificity. That is likely because the TMDL’s provisions
that could be read to affect land use are either explicitly
allowed by federal law or too generalized to supplant state
zoning powers in any extraordinary way.

        The TMDL comes closest to dictating a land-use
regulation by allocating pollution limits to specific point
sources. See Appendix R. As each of these sources is
regulated by the National Pollutant Discharge Elimination
System, see 33 U.S.C. § 1342, and the TMDL’s allocations
are not alleged to be inconsistent with that scheme, these
waste load allocations do not trespass onto an area of
traditional state regulation to some greater degree than the
Clean Water Act anticipates.
       The next most intrusive aspect of the TMDL is its
allocations of limits to nonpoint-source sectors, as opposed to
specific sources. The TMDL prescribes

       daily Land Based [Load Allocation]s for
       specific nonpoint source sectors: agriculture,
       forest, nontidal atmospheric deposition, onsite
       septic, and urban.        Land Based [Load
       Allocations] are presented as delivered load for
       each of the 92 impaired segments by
       jurisdiction and by nonpoint source sector for
       [total nitrogen, total phosphorous, and total
       suspended solids].




                              45
J.A. 1597 (emphases added); see also TMDL Appendix R. In
presenting load allocations by sector, the TMDL gives the
states flexibility in achieving the limits the EPA set—
preserving state autonomy in land-use and zoning.

        Further undermining the claim that the TMDL
impermissibly takes over state power to regulate land is that
the TMDL nowhere prescribes any particular means of
pollution reduction to any individual point or nonpoint
source. Instead, it contains pollution limits and allocations to
be used as an informational tool used in connection with a
state’s efforts to regulate water pollution. This conclusion is
confirmed by the Act, as it requires states to have a
“continuing planning process,” which must include (but is not
limited to) “total maximum daily load[s].” 33 U.S.C.
§ 1313(e)(1) & (3). It is further confirmed by the language of
the TMDL, which provides that “[t]he cornerstone of the
accountability framework is the jurisdictions’ development of
[Watershed Improvement Plans], which serve as roadmaps
for how and when a jurisdiction plans to meet its pollutant
allocations under the TMDL,” J.A. 1113, and by the EPA’s
repeated concessions that it will not undertake any
enforcement action under the TMDL. Tr. of Oral Argument
at 91:3, Oct. 4, 2012, American Farm Bureau Fed’n v. EPA,
No. 11-cv-67 (M.D. Pa.), J.A. 1758; EPA Response Br. at 23.

       Farm Bureau characterizes the TMDL as more than an
informational tool by pointing to incentives for states to
implement it. By virtue of 33 U.SC. § 1313(e), the TMDL
must be included in each state’s “continuing planning
process,” something the states are ostensibly required to put
in place.6 The sanction for failing to adopt an adequate
6
  From the record before us, it is not clear that any
Chesapeake Bay state has or will adopt a continuing planning
process within the meaning of § 1313(e), or that such a




                              46
continuing planning process under § 1313(e) is that the state
loses its authority to administer its portion of the National
Pollution Discharge Elimination System.            33 U.S.C.
§ 1313(e)(2). Another means of incentivizing states to follow
the TMDL involves overseeing their implementation of
Watershed Improvement Plans. “If progress is insufficient,
EPA will utilize contingencies to place additional controls on
federally permitted sources of pollution . . . as well as target
compliance and enforcement activities.” J.A. 1118. The EPA
lays out in more detail what these compliance and
enforcement activities may be in Section 7.2.4 of the TMDL;
they include establishing finer-scale waste load allocations
and load allocations (i.e., more tightly overseeing states’
pollution control) and conditioning federal grants based on
progress in implementing the Watershed Improvement Plans
(i.e., withholding money if progress is unsatisfactory). The
allocations are not self-executing, and all the other
enforcement actions concern administration of federal
programs plainly within the EPA’s authority.

       Despite these incentives, Farm Bureau does not argue
that the “inducement offered by Congress” for the states to
adopt and enforce the TMDL is “so coercive as to pass the
point at which pressure turns into compulsion.” South Dakota
v. Dole, 483 U.S. 203, 211 (1987) (internal quotation marks
omitted). Because Farm Bureau does not say that the EPA
coerced the states into accepting the TMDL and because it
only obliquely affects land use regulations, we conclude that



process will include the TMDL, but the states’ Phase II
Watershed Improvement Plans, which are to be implemented
now that the TMDL has been published, may satisfy the
statute’s requirements.




                              47
the TMDL does not prescribe land use rules that excessively
intrude on traditional state authority.

       Put another way, it is illogical to assert that the EPA
usurps states’ traditional land-use authority when it (1) makes
no actual, identifiable, land-use rule and (2) proposes
regulatory actions that are specifically allowed under federal
law. Hence we fail to see how this case presents federalism
concerns so significant as to require a “clear statement” from
Congress called for in SWANCC before we prohibit the
EPA’s interpretation of the statute. When a statutory scheme
clearly inserts the federal Government into an area of typical
state authority, we may require a plain statement from
Congress about the scope of the statute’s applicability before
upholding an agency’s assertion of jurisdiction over an area
(physical or legal) historically regulated by the states. But, as
here, once an agency is operating in the weeds of a statute
that obviously requires federal oversight of some state
functions, we will not require subordinate clear statements of
congressional intent every time an interpretation arguably
varies the usual balance of responsibilities between federal
and state sovereigns.

       We add an important caveat: if an agency interprets a
statute in a way that pushes a constitutional boundary
(whether that boundary comes from the federal structure or a
different constitutional principle), we may find that
interpretation outside the scope of Congress’s delegation if it
does not clearly flow from the statutory text. That brings us
to the next question. Does the EPA’s interpretation of “total
maximum daily load” push at the Constitution’s outer
bounds?




                               48
                     ii.    Constitutional Avoidance

        When the TMDL is implemented, some land will need
to be used differently from the way it is now, and it is true
that land use law is an area typically within the states’ police
power. At the same time, federal power over interstate
waterways, “from the commencement of the [federal]
government, has been exercised with the consent of all, and
has been understood by all to be a commercial regulation.”
Gibbons v. Ogden, 22 U.S. (9 Wheat) 1, 190 (1824). And for
at least a century, federal common law has governed disputes
over interstate water pollution. Arkansas v. Oklahoma, 503
U.S. at 98 (citing Missouri v. Illinois, 200 U.S. 496 (1906),
and Georgia v. Tennessee Copper Co., 206 U.S. 230 (1907)).

        Regulation of the channels of interstate commerce lies
at the very core of Congress’s commerce power. E.g., United
States v. Lopez, 514 U.S. 549, 558 (1995) (“[W]e have
identified three broad categories of activity that Congress
may regulate under its commerce power. First, Congress may
regulate the use of the channels of interstate commerce.”
(citations omitted)); Heart of Atlanta Motel, Inc. v. U.S., 379
U.S. 241, 256 (1964) (“[T]he authority of Congress to keep
the channels of interstate commerce free from immoral and
injurious uses has been frequently sustained, and is no longer
open to question.”). And there can be no serious question that
the Chesapeake Bay is a channel of interstate commerce: it
produces 500 million pounds of seafood per year, leads ships
to many port towns (including Baltimore), and has an
estimated economic value of more than one trillion dollars.
EPA Response Br. at 4. Broadly speaking, then, the federal
Government’s traditional authority to regulate this part of the
country is secure.

      By contrast, in Clean Water Act cases where there
were arguable Commerce Clause problems, the SWANCC




                              49
Court would not interpret the Act to confer federal
jurisdiction over an abandoned, man-made sand and gravel pit
absent a “clear statement” from Congress to that effect
because such an interpretation raised serious constitutional
concerns (that the Government had failed to identify an
activity that substantially affected interstate commerce, 531
U.S. at 173), and the Rapanos plurality rejected the Corps’
interpretation of the “waters of the United States” to include
wetlands near ditches that eventually drain into navigable
waters because that understanding “presses the envelope of
constitutional validity.” 547 U.S. at 738.

        Moreover, in Rapanos it appears five justices had no
constitutional concerns in any event. Justice Kennedy, who
provided the fifth vote to vacate the Sixth Circuit’s judgment,
concluded only that the Court of Appeals had not faithfully
applied SWANCC. Id. at 759. He forcefully rejected the
plurality’s reasoning, id. at 776 (“[T]he plurality’s opinion is
inconsistent with the Act’s text, structure, and purpose.”), and
asserted a broad theory of federal authority under the
Commerce Clause:
       Even assuming, then, that federal regulation of remote
       wetlands and nonnavigable waterways would raise a
       difficult Commerce Clause issue notwithstanding those
       waters’ aggregate effects on national water quality, but
       cf. Wickard v. Filburn, 317 U.S. 111 (1942); see also
       infra, at 2249–2250 [citing Justice Stevens’s dissent],
       the plurality’s reading is not responsive to this
       concern. As for States’ “responsibilities and rights,”
       [33 U.S.C.] § 1251(b), it is noteworthy that 33 States
       plus the District of Columbia have filed an amici brief
       in this litigation asserting that the Clean Water Act is




                              50
       important to their own water policies.[7] These amici
       note, among other things, that the Act protects
       downstream States from out-of-state pollution that
       they cannot themselves regulate.

Id at 777. Justice Stevens and the three other dissenters who
joined him would have held that it was reasonable and

7
   We recognize that private parties may rely on the
Constitution’s structural division of labor between states and
the federal Government to argue that one has gone too far.
See, e.g., United States v. Morrison, 529 U.S. 598, 654 (2000)
(Souter, J. dissenting) (“Thirty-six [states] and the
Commonwealth of Puerto Rico have filed an amicus brief in
support of petitioners in these cases, and only one State has
taken respondents’ side. It is, then, not the least irony of these
cases that the States will be forced to enjoy the new
federalism whether they want it or not.”). And in any event
the rooting interests of the states (both those directly affected
by the TMDL and others) are not one-sided here. None of the
seven states within the Chesapeake Bay’s watershed sued the
EPA over this TMDL. Virginia, Maryland, Delaware, and the
District of Columbia have filed briefs in support of the
District Court’s decision, while West Virginia has signed on
to the amici brief of states that oppose the EPA’s decision.
The other states (Pennsylvania and New York) are on the
sidelines, but local governments are involved: municipalities
from both states have filed amici briefs in favor of the EPA;
on the other hand, six Pennsylvania counties and one
Delaware county have filed a brief in support of Farm
Bureau. Last, 21 other states have filed an amici brief in
support of Farm Bureau, relying primarily on federalism
arguments.




                               51
constitutional for the Corps to include within the definition of
“waters of the United States” wetlands that drain into
navigable waters. Id. at 788.

        Notwithstanding the constitutional concerns raised in
those cases, SWANCC and Rapanos are easily distinguishable
on the critical and obvious ground that we are not concerned
here with a small intrastate area of wetland; we are dealing
with North America’s largest estuary. Indeed, the Rapanos
plurality approvingly quoted a previous case for the
proposition that “‘[i]n view of the breadth of federal
regulatory authority contemplated by the Act itself and the
inherent difficulties of defining precise bounds to regulable
waters, the Corps’ ecological judgment about the relationship
between waters and their adjacent wetlands provides an
adequate basis for a legal judgment that adjacent wetlands
may be defined as waters under the Act.’” Id. at 740–41
(quoting United States v. Riverside Bayview Homes, Inc., 474
U.S. 121, 134 (1985) (emphasis in Rapanos)). It is beyond
debate that navigable-in-fact waters are regulable and that the
Chesapeake Bay is navagible-in-fact. SWANCC and Rapanos
are also distinguishable because no one here is challenging
the EPA’s authority to set a total maximum daily load; rather,
Farm Bureau challenges how the EPA is allowed to express
the load and what it may consider in drafting the TMDL.
And, although Justice Kennedy’s concurrence is Delphic on
this point, it appears that in Rapanos five Justices had no
constitutional concerns. For us, the key point is that, in terms
of the conflict between state and federal regulatory authority,
we are far removed from SWANCC and Rapanos.

      Because the TMDL forms part of a plan to clean up a
channel of interstate commerce, we have no constitutional
concerns with the EPA’s interpretation of the statute.




                              52
                    5.     Conclusion With Respect to Step
                           One

        “Total” is susceptible to multiple meanings.
Interpreting “total maximum daily load” as requiring one
number and nothing more is in tight tension with the Clean
Water Act’s goal of providing a cooperative framework for
states and the federal Government to work together to
eliminate water pollution. The Act’s structure supports that
TMDLs need to account for point and nonpoint sources, but
the Act is silent on how to account for those sources. It is
also silent on (1) whether the EPA in calculating a TMDL
may consider and express the time frames within which it and
the states will strive to achieve water quality standards and
(2) the extent to which the EPA may consider and express
whether a state will meet the goals it sets (the “reasonable
assurance” requirement). Last, the APA prefers overt rather
than covert reasoning by agencies. For these reasons, we
conclude that the phrase “total maximum daily load” is
ambiguous enough to allow the EPA to include the elements
of the TMDL challenged here.
      D.     Chevron Step Two

       We briefly summarize the reasoning from Step One
that also supports the EPA’s Step Two argument (Farm
Bureau merely repeats its Step One contentions at Step Two,
so there is no need to dive too deep here). As noted above,
“total” can mean “a sum of parts,” and interpreting “total”
that way gives greater guidance to states in cleaning their
waters, provides greater transparency to the public who may
comment on a TMDL, and furthers the Act’s requirement that
the TMDL account for both point and nonpoint sources.
Moreover, expressing the allocation of pollution limits
between the EPA-regulated point sources and state-regulated
nonpoint sources furthers the Clean Water Act’s goal of




                             53
achieving water quality standards. Including deadlines in a
TMDL furthers the Act’s goal that the TMDL promptly
achieve something beneficial (recall that the enacting
Congress’s goal was to have the Nation’s waters clean by
1985), and the reasonable assurance requirement helps guide
the EPA’s discretion in determining whether to approve a
TMDL or a state’s mandatory “continuing planning process,”
which must include the TMDL, 33 U.S.C. § 1313(e), as it
would surely be arbitrary or capricious for the EPA to
approve a plan that a state is incapable of following.

       In addition to the factors just discussed, at Step Two
we may consider legislative history to the extent that it may
clarify the policies framing the statute.8 And we must

8
  In United States v. Geiser, 527 F.3d 288, 294 (3d Cir. 2008),
we wrote “that legislative history should not be considered at
Chevron step one.” This statement is a well-considered
precedent of our Court, and we adhere to it here.
        There is an argument that Geiser’s language excising
legislative history from Step One is too broad. It derives
from discussions of how to construe unambiguous language.
See id., 527 F.3d at 293 (citing Zuni Pub. Sch. Dist. 89 v.
Dep’t of Educ., 550 U.S. 81, 93 (2007); Dep’t of Hous. &
Urban Dev. v. Rucker, 535 U.S. 125, 132–33 (2002)).
Legislative history is generally not used to assess whether the
words of a statute are ambiguous or to interpret unambiguous
words. See Milner v. Dep’t of Navy, 131 S. Ct. 1259, 1267
(2011). But at Step One we consider (1) whether a statute is
ambiguous, and, if so, (2) whether the agency’s interpretation
falls within the scope of the ambiguity and (3) whether the
ambiguity signifies a congressional delegation. See supra
Part IV.A (discussing content of Chevron inquiry); United
States v. Home Concrete & Supply, LLC, 132 S. Ct. 1836,




                              54
1844 (2012) (opinion of Breyer, J.) (concluding despite
“linguistic ambiguity” that Congress had not “delegated gap-
filling power to the agency”). Legislative history can be
helpful in the latter inquiries. If, for example, a committee
report notes that Congress has left a gap for an agency to fill,
one might question whether that would be relevant to a judge
who considers the use of legislative history to be permissible.
See, e.g., H.R. Rep 92-911 at 93 (“The use of the word
‘generally’ is intended to provide the Administrator with
some discretion . . . .”).
        Geiser’s holding on when we may consult legislative
history in construing statutes is arguably in tension with the
Supreme Court’s general practice of declining to make
interpretive methodologies binding (as academics put it, the
Court typically avoids “methodological stare decisis”),
particularly in the context of legislative history. See Evan J.
Criddle & Glen Staszewski, Against Methodological Stare
Decisis, 102 Geo. L.J. 1573, 1576 (2014) (“[F]ederal courts
do not treat interpretive methodology as a traditional form of
‘law,’ and federal judges are therefore permitted to use
whichever interpretive methods they prefer to resolve each
particular case.”); Abbe R. Gluck, The States as Laboratories
of Statutory Interpretation: Methodological Consensus and
the New Modified Textualism, 119 Yale L.J. 1750, 1765
(2010) (“Indeed, the Court does not give stare decisis effect to
any statements of statutory interpretation methodology.”
(emphasis in original)); Jordan Wilder Connors, Treating Like
Subdecisions Alike: The Scope of Stare Decisis as Applied to
Judicial Methodology, 108 Colum. L. Rev. 681, 707 (2008);
Jonathan R. Siegel, The Polymorphic Principle and the
Judicial Role in Statutory Interpretation, 84 Tex. L. Rev. 339,
389 (2005); Nicholas Quinn Rosenkranz, Federal Rules of




                              55
consider whether the agency made “‘a reasonable policy
choice’” in its interpretation. Brand X, 545 U.S. at 997
(quoting Chevron, 467 U.S. at 845).

        Although the parties do not cite any pre-enactment
legislative history that describes the meaning of “total
maximum daily load,” one committee report, by the House
Public Works Committee, commented in discussing draft
legislation that “[a] maximum daily load shall also be
developed by a State for all waters within its boundaries
which are not identified as requiring more stringent effluent
limitations to meet water quality standards. The committee
recognizes that this is a time-consuming and difficult task.”
H.R. Rep. No. 92-911, at 106 (1972). This is the only
discussion in the pre-enactment legislative history of the
TMDL requirement, and it provides no help beyond
recognizing that developing a TMDL is “time consuming and
difficult.” If anything, this undercuts the idea that a TMDL is
just a number, but it offers only weak support at best for the
EPA.

       Post-enactment developments are more informative.
Specifically, in 1987, after the EPA had defined “total
maximum daily load” as the sum of waste load allocations for
point sources and load allocations for nonpoint sources,
Congress added § 1313(d)(4)(A) & (B) governing the
revision of effluent limitations “based on a total maximum
daily load or other waste load allocation established under


Statutory Interpretation, 115 Harv. L. Rev. 2085, 2144–45
(2002). However, as whether we consider legislative history
at Step One or Step Two does not affect the outcome of this
case, we have no occasion to explore further the contours of
this debate. We follow the instruction in Geiser and turn to
the relevant legislative history at Chevron’s second step.




                              56
this section.” P.L. 100-4 § 404(b) (Feb. 4, 1987) (emphasis
added). The word “other” suggests that a TMDL contains a
waste load allocation. Interestingly, § 1313 makes no
reference to a “waste load allocation”; that phrase occurs only
in the EPA’s regulations. The EPA therefore has a strong
argument that Congress not only agreed to its definition of
TMDL as the sum of load and waste load allocations, but also
affirmatively incorporated the EPA’s rule in an addition to the
statute.

        A second development in 1987 was that Congress
ratified the Chesapeake Bay Program, a voluntary partnership
among several watershed states and the EPA. See 33 U.S.C.
§ 1267. The 1987 legislation supported cleanup efforts by a
program of grants and study; in 2000 Congress added
§ 1267(g), which directed the EPA to “ensure that
management plans are developed and implementation is
begun” to meet the goals of the Chesapeake Bay Agreement.
Although § 1267 does not add to the EPA’s regulatory
authority, it strongly suggests that cleaning up the Bay is a
priority for Congress and that it did not have a problem with
the EPA’s role in developing goals for the watershed even
though the EPA had promulgated its TMDL rules long before
§ 1267 was added to the U.S. Code.
       Farm Bureau claims that Congress, far from
acquiescing to the regulatory definitions of the EPA, has
specifically rejected its “reasonable assurance” requirement
by blocking implementation of an EPA rule in 2000. 68 Fed.
Reg. 13,608–09 (Mar. 19, 2003). As the EPA convincingly
counters, the entire rule was blocked for just one year,
contained dozens of changes to the EPA’s Clean Water Act
regulations (which included the reasonable assurance
requirement), and was ultimately withdrawn in its entirety in
2003. Farm Bureau gives no reason to think that Congress




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blocked the rule because of the reasonable assurance
requirement.

       Although legislative history in general and
“congressional acquiescence” in particular are controversial
legal methods, to the extent they have the power to persuade,
they provide support to the EPA that it has reasonably carried
out Congress’s directives in administering the TMDL section
of the Clean Water Act.

       More to the point, even Farm Bureau “agree[s] with
EPA that developing source limits, assurances, and deadlines
is useful.” Reply Br. at 2. Although Farm Bureau claims that
the Chesapeake Bay will be cleaned up without EPA
intervention, the contention defies common sense and
experience. The Clean Water Act sought to eliminate water
pollution by 1985, but by 2010 62% of the Bay had
insufficient oxygen to support aquatic life, and only 18% of
the Bay had acceptable water clarity. NGO Response Br. at
6.

       In an important article on the allocation of property
rights in land, Robert Ellickson distinguished among small,
medium, and large events (using, he acknowledged tongue-in-
cheek, “highly sophisticated adjectives”).          Robert C.
Ellickson, Property in Land, 102 Yale L.J. 1315, 1325
(1993). “Large events,” he noted, “are inherently difficult to
regulate. Identifying the institutions that govern them best—
or, more bluntly, least badly—should be an exercise in
experience, not logic.” Id. at 1335. The drainage of 64,000
square miles of land into the continent’s largest estuary
qualifies as a large event, and it has proved difficult to
regulate. Our experience in state regulation of water
pollution gave environmentalists poster material in the 1969
burning of the Cuyahoga River, the consequence of a classic
“tragedy of the commons,” which occurs when society fails to




                             58
create incentives to use a common resource responsibly. See
Garrett Hardin, The Tragedy of the Commons, 162 Science
1243, 1244 (1968). Producers of industrial waste used the
Cuyahoga River to diffuse oil and other chemicals—and thus
the river “ooze[d] rather than flow[ed]” and a person who fell
in would “not drown but decay”—until the waste caught fire.
Time, America’s Sewage System and the Price of Optimism
(Aug. 1, 1969). In response to that fire and to the general
degradation of American water that followed the post-war
industrial boom, Congress determined that the EPA should
have a leadership role in coordinating among states to restore
the Nation’s waters to something approaching their natural
state. See 33 U.S.C. § 1251. The EPA has carried out that
duty by publishing approximately 61,000 TMDLs with a level
of detail commensurate with the challenge of cleaning and
maintaining our waters. The EPA’s approach makes sense, as
even Farm Bureau acknowledges, and therefore represents a
reasonable policy choice at Chevron’s second step.

        Farm Bureau’s reading of the Act would stymie the
EPA’s ability to coordinate among all the competing possible
uses of the resources that affect the Bay. At best, it would
shift the burden of meeting water quality standards to point
source polluters, but regulating them alone would not result in
a clean Bay. See supra Part IV.B.3.i (explaining how 33
U.S.C. § 1313(d) requires “impaired waters” to be listed only
when point source regulation is insufficient to meet water
quality standards). As the Supreme Court has admonished in
the water-pollution context, “We cannot, in these
circumstances, conclude that Congress has given authority
inadequate to achieve with reasonable effectiveness the
purposes for which it has acted.” E.I. Du Pont De Nemours v.
Train, 430 U.S. 112, 132 (1977) (quoting Permian Basin
Area Rate Cases, 390 U.S. 747, 777 (1968)). Establishing a
comprehensive, watershed-wide TMDL—complete with
allocations among different kinds of sources, a timetable, and




                              59
reasonable assurance that it will actually be implemented—is
reasonable and reflects a legitimate policy choice by the
agency in administering a less-than-clear statute. Therefore
we uphold these decisions at Chevron Step Two.

V.     Conclusion

        Water pollution in the Chesapeake Bay is a complex
problem currently affecting at least 17,000,000 people (with
more to come). Any solution to it will result in winners and
losers. To judge from the arguments and the amici briefs
filed in this case, the winners are environmental groups, the
states that border the Bay, tourists, fishermen, municipal
waste water treatment works, and urban centers. The losers
are rural counties with farming operations, nonpoint source
polluters, the agricultural industry, and those states that would
prefer a lighter touch from the EPA. Congress made a
judgment in the Clean Water Act that the states and the EPA
could, working together, best allocate the benefits and
burdens of lowering pollution. The Chesapeake Bay TMDL
will require sacrifice by many, but that is a consequence of
the tremendous effort it will take to restore health to the
Bay—to make it once again a part of our “land of living,”
Robert Frost, The Gift Outright line 10—a goal our elected
representatives have repeatedly endorsed. Farm Bureau’s
arguments to the contrary are unpersuasive, and thus we
affirm the careful and thorough opinion of the District Court.




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