
    ENVIRONMENTAL DEFENSE CENTER, INC., Petitioner, Natural Resources Defense Council, Inc., Petitioner-Intervenor, v. UNITED STATES ENVIRONMENTAL PROTECTION AGENCY, Respondent. American Forest & Paper Association; National Association of Home Builders, Petitioners, v. United States Environmental Protection Agency, Respondent, Natural Resources Defense Council, Inc., Applicant-Intervenor. Texas Cities Coalition on Stormwater; Texas Counties Storm Water Coalition, Petitioners, v. United States Environmental Protection Agency, Respondent, Natural Resources Defense Council, Inc., Respondent-Intervenor.
    Nos. 00-70014, 00-70734, 00-70822.
    United States Court of Appeals, Ninth Circuit.
    Argued and Submitted Dec. 3, 2001.
    Filed Sept. 15, 2003.
    
      Victoria Clark, Environmental Defense Center, Santa Barbara, CA, for petitioner Environmental Defense Center, Inc.
    Andrew G. Frank and Arlene Yang, Paul, Weiss, Rifkind, Wharton & Garrison, New York, NY, and Nancy K. Stoner, Natural Resources Defense Council, Washington, DC, for intervenor National Resources Defense Council, Inc.
    R. Timothy McCrum, Ellen B. Steen, and Donald J. Kochan, Crowell & Moring, Washington, DC, for petitioners American Forest & Paper Association and National Association of Home Builders.
    Steven P. Quarles and J. Michael Klise, Crowell & Moring, Washington, DC, and William R. Murray, American Forest & Paper Association, Washington, DC, for petitioner American Forest & Paper Association.
    Jim Mathews and Clarence Joe Free-land, Mathews & Freeland, Austin, TX, for petitioner Texas Cities Coalition on Storm-water.
    Sydney W. Falk, Jr. and William D. Dugat III, Bickerstaff, Heath, Smiley, Pol-lan, Kever & McDaniel, Austin, TX, for petitioner Texas Counties Storm Water Coalition.
    John C. Cruden, Daniel M. Flores and Kent E. Hanson, United States Department of Justice, Washington, DC, and Stephen J. Sweeny, United States Environmental Protection Agency, Washington, DC, for respondent United States Environmental Protection Agency.
   Opinion by Judge JAMES R. BROWNING; Partial Concurrence and Partial Dissent by Judge TALLMAN.

ORDER AND OPINION

ORDER

The opinion and dissent filed in this case on January 14, 2003, and published at 319 F.3d 398 are vacated. They are replaced by the Opinion and Dissent filed today.

With the filing of the new Opinion and Dissent, the panel has voted to deny the petitions for rehearing and the petition for rehearing en banc. (Judge Tallman would grant the petition for rehearing filed by the Environmental Protection Agency.) The full court has been advised of the new Opinion, new Dissent, and petition for rehearing en banc. No judge has requested a vote on the petition for rehearing en banc. Fed. R.App. P. 35.

The petitions for rehearing and the petition for rehearing en banc are DENIED. The clerk is instructed not to accept for filing any new petitions for rehearing or petitions for rehearing en banc in this case.

Each party shall bear its own costs in this appeal.

OPINION

JAMES R. BROWNING, Circuit Judge.

Petitioners challenge a rule issued by the United States Environmental Protection Agency pursuant to the Clean Water Act, 33 U.S.C. §§ 1251-1387, to control pollutants introduced into the nation’s waters by storm sewers.

Storm sewers drain rainwater and melted snow from developed areas into water bodies that can handle the excess flow. Draining stormwater picks up a variety of contaminants as it filters through soil and over pavement on its way to sewers. Sewers are also used on occasion as an easy (if illicit) means for the direct discharge of unwanted contaminants. Since storm sewer systems generally channel collected runoff into federally protected water bodies, they are subject to the controls of the Clean Water Act.

In October of 1999, after thirteen years in process, the Environmental Protection Agency (“EPA”) promulgated a final administrative rule (the “Phase II Rule” or “the Rule”) under § 402(p) of the Clean Water Act, 33 U.S.C. § 1342(p), mandating that discharges from small municipal separate storm sewer systems and from construction sites between one and five acres in size be subject to the permitting requirements of the National Pollutant Discharge Elimination System (“NPDES”), 33 U.S.C. §§ 1311(a), 1342. EPA preserved authority to regulate other harmful storm-water discharges in the future.

In the three cases consolidated here, petitioners and intervenors challenge the Phase II Rule on twenty-two constitutional, statutory, and procedural grounds. We remand three aspects of the Rule concerning the issuance of notices of intent under the Rule’s general permitting scheme, and a fourth aspect concerning the regulation of forest roads. We affirm the Rule against all other challenges.

I.

BACKGROUND

A. The Problem of Stormwater Runoff

Stormwater runoff is one of the most significant sources of water pollution in the nation, at times “comparable to, if not greater than, contamination from industrial and sewage sources.” Storm sewer waters carry suspended metals, sediments, algae-promoting nutrients (nitrogen and phosphorus), floatable trash, used motor oil, raw sewage, pesticides, and other toxic contaminants into streams, rivers, lakes, and estuaries across the United States. In 1985, three-quarters of the States cited urban stormwater runoff as a major cause of waterbody impairment, and forty percent reported construction site runoff as a major cause of impairment. Urban runoff has been named as the foremost cause of impairment of surveyed ocean waters. Among the sources of stormwater contamination are urban development, industrial facilities, construction sites, and illicit discharges and connections to storm sewer systems.

B. Stormwater and the Clean Water Act

Congress enacted the Clean Water Act in 1948 to “restore and maintain the chemical, physical, and biological integrity of the Nation’s waters.” 33 U.S.C. § 1251(a) (originally codified as the Federal Water Pollution Control Act, 62 Stat. 1155). The Clean Water Act prohibits the discharge of pollutants from a “point source” into the waters of the United States without a permit issued under the terms of the National Pollutant Discharge Elimination System, 33 U.S.C. §§ 1311(a), 1342, which requires dischargers to comply with technology-based pollution limitations (generally according to the “best available technology economically achievable,” or “BAT” standard). 33 U.S.C. § 1311(b)(2)(A). NPDES permits are issued by EPA or by States that have been authorized by EPA to act as NPDES permitting authorities. 33 U.S.C. § 1342(a)-(b). The permitting authority must make copies of all NPDES permits and permit applications available to the public, 33 U.S.C. §§ 1342(j), 1342(b)(3); state permitting authorities must provide EPA notice of each permit application, 33 U.S.C. § 1342(b)(4); and a permitting authority must provide an opportunity for a public hearing before issuing any permit, 33 U.S.C. §§ 1342(a)(1), 1342(b)(3); cf. 33 U.S.C. § 1251(e) (requiring public participation).

Storm sewers are established point sources subject to NPDES permitting requirements. Natural Res. Def. Council v. Costle, 568 F.2d 1369, 1379 (D.C.Cir.1977) (holding unlawful EPA’s exemption of stormwater discharges from NPDES permitting requirements); Natural Res. Def. Council v. EPA, 966 F.2d 1292, 1295 (9th Cir.1992). In 1987, to better regulate pollution conveyed by stormwater runoff, Congress enacted Clean Water Act § 402(p), 33 U.S.C. §. 1342(p), “Municipal and Industrial Stormwater Discharges.” Sections 402(p)(2) and 402(p)(3) mandate NPDES permits for stormwater discharges “associated with industrial activity,” discharges from large and medium-sized municipal storm sewer systems, and certain other discharges. Section 402(p)(4) sets out a timetable for promulgation of the first of a two-phase overall program of stormwater regulation. Id. at § 1342(p)(2)-(4); Natural Res. Def. Council, 966 F.2d at 1296. In 1990, pursuant to § 402(p)(4), EPA issued the Phase I Rule regulating large discharge sources.

C. The Phase II Stormwater Rule

In Clean Water Act § 402(p), Congress also directed a second stage of stormwater regulation by ordering EPA to identify and address sources of pollution not covered by the Phase I Rule. Section 402(p)(l) placed a temporary moratorium (expiring in 1994) on the permitting of other storm-water discharges pending the results of studies mandated in § 402(p)(5) to identify the sources and pollutant content of such discharges and to establish procedures and methods to control them as “necessary to mitigate impacts on water quality.” 33 U.S.C. § 1342(p)(5). Section 402(p)(6) required that EPA establish “a comprehensive program to regulate” these stormwa-ter discharges “to protect water quality,” following the studies mandated in § 402(p)(5) and consultation with state and local officials. Id. at § 1342(p)(6).

EPA proposed the Phase II Rule in January of 1998. In October, 1999, Congress passed legislation precluding EPA from promulgating the new Rule until EPA submitted an additional report to Congress supporting certain anticipated aspects of the Rule. EPA was also required to publish its report in the Federal Register for public comment. Pub. L. No. 106-74, § 431(c), 113 Stat. at 1097. Later that month, EPA submitted the required (“Appropriations Act”) study and promulgated the Rule.

Under the Phase II Rule, NPDES permits are required for discharges from small municipal separate storm sewer systems (“small MS4s”) and stormwater discharges from construction activity disturbing between one and five acres (“small construction sites”). 40 C.F.R. §§ 122.26(a)(9)(i)(A)-(B). Small MS4s may seek permission to discharge by submitting an individualized set of best-management plans in six specified categories, id. at § 122.34, either in the form of an individual permit application, or in the form of a notice of intent to comply with a general permit. Id. at § 122.33(b). Small MS4s may also seek permission to discharge through an alternative process, under which a permit may be sought without requiring the operator to regulate third parties, id. at §§ 122.33(b)(2)(ii), 122.26(d). Small construction sites may apply for individual NPDES permits or seek coverage under a promulgated general permit. Id. at § 122.26(c). EPA also preserved authority to regulate other categories of harmful stormwater discharges on a regional, as-needed basis. Id. at § 122.26(a)(9)(i)(C)-(D).

D. Facial Challenges to the Phase II Rule

The Rule was challenged in the Fifth, Ninth, and D.C. Circuits in three separate actions ultimately consolidated before the Ninth Circuit.

The Texas Cities Coalition on Stormwa-ter and the Texas Counties Stormwater Coalition (collectively, “the Municipal Petitioners”) assert that EPA lacked authority to require permitting, that its promulgation of the Rule was procedurally defective, that the Rule establishes categories that are arbitrary and capricious, and that the Rule impermissibly requires municipalities to regulate their own citizens in contravention of the Tenth Amendment and to communicate a federally mandated message in contravention of the First Amendment. The Natural Resources Defense Council (“NRDC”) intervened on behalf of EPA.

Environmental Defense Center, joined by petitioner-intervenor NRDC (“the Environmental Petitioners”), asserts that the regulations fail to meet minimum Clean Water Act statutory requirements because they constitute a program of impermissible self-regulation, fail to provide required avenues of public participation, and neglect to address stormwater runoff associated with forest roads and other significant sources of runoff pollution.

The American Forest & Paper Association (“AF&PA”) and the National Association of Home Builders (“the Industrial Petitioners”) assert that promulgation of the Rule was procedurally defective and violated the Regulatory Flexibility Act, that EPA’s retention of authority to regulate future sources of runoff pollution is ultra vires, and that the decision to regulate discharge from construction sites one to five acres in size is arbitrary and capricious. NRDC again intervened on behalf of EPA.

We have jurisdiction pursuant to section 509(b)(1) of the Clean Water Act, 33 U.S.C. § 1369(b)(1) (assigning review of EPA effluent and permitting regulations to the Federal Courts of Appeals).

II.

DISCUSSION

A. The Permit Requirements

The Municipal Petitioners’ primary contention is that the Phase II Rule compels small MS4s to regulate citizens as a condition of receiving a permit to operate, and that EPA lacks both statutory and constitutional authority to impose such a requirement. Because we avoid considering constitutionality if an issue may be resolved on narrower grounds, Greater New Orleans Broadcasting Ass’n v. United States, 527 U.S. 173, 184, 119 S.Ct. 1923, 144 L.Ed.2d 161 (1999), we first ask whether the Phase II Rule is supported by statutory authority.

1. Statutory Authority

The Municipal Petitioners assert that the statutory command in Clean Water Act § 402(p)(6) that EPA develop a “comprehensive program to regulate” small MS4s did not authorize a program based on NPDES permits. Petitioners argue that because § 402(p)(6) explicitly indicates elements that the program may contain (performance standards, guidelines, etc.) without mentioning “permits,” Congress must have intended that the program exclude permitting.

The fact that “permitting” is not included on a statutory list of elements that the program “may” include is not determinative, because the list is manifestly nonexclusive. The only constraints are that the § 402(p)(6) regulations be based on the § 402(p)(5) studies, that they be issued in consultation with state and local officials, and that — “at a minimum” — they establish priorities, requirements for state stormwater management programs, and expeditious deadlines, and constitute a comprehensive program “to protect water quality.” 33 U.S.C. § 1342(p)(6). EPA was free to adopt any regulatory program, including a permitting program, that included these elements. See Chevron, U.S.A. v. Natural Res. Def. Council, 467 U.S. 837, 842-43, 104 S.Ct. 2778, 81 L.Ed.2d 694 (1984) (deference to an agency’s reasonable interpretation is required unless Congress expressed its intent unambiguously). It is more reasonable to interpret congressional silence about permits as an indication of EPA’s flexibility not to use them than as an outright prohibition.

The Municipal Petitioners further contend that their interpretation is supported by the structure of § 402(p), which expressly requires permits for large and medium sized MS4s in a separate section, § 402(p)(3)(B). However, as EPA counters, the language in § 402(p)(3) requiring permits for municipal storm sewers may be interpreted to apply both to Phase I and Phase II MS4s. Moreover, as respondent-intervenor NRDC notes, the mere existence of the § 402(p)(l) permitting moratorium, designed to apply only to Phase II dischargers, necessarily implies that EPA has the authority to require permits from these sources after the 1994 expiration of the moratorium.

Since there would have been no need to establish a permitting moratorium for these sources if the sources could never be subject to permitting requirements, petitioners’ interpretation violates the bedrock principle that statutes not be interpreted to render any provision superfluous. See Burrey v. Pacific Gas & Elec. Co., 159 F.3d 388, 394 (9th Cir.1998). EPA’s interpretation of its mandate under § 402(p)(6) was reasonable and EPA acted within its statutory authority in formulating the Phase II Rule as a permitting program.

2. The Tenth Amendment

The Municipal Petitioners contend that the Phase II Rule on its face compels operators of small MS4s to regulate third parties in contravention of the Tenth Amendment. We conclude that the Rule does not violate the Tenth Amendment, because it directs no unconstitutional coercion.

The Phase II Rule contemplates several avenues through which a small MS4 may obtain permission to discharge. First, if the NPDES Permitting Authority overseeing the small MS4 has issued an applicable general permit, the small MS4 may submit a notice of intent wherein the small MS4 agrees to comply with the terms of the general permit and specifies plans for implementing six “Minimum Measures” designed to protect water quality. 40 C.F.R. §§ 122.33(b)(1), 122.34(d)(1)®, 122.34(b). Second, the small MS4 may apply for an individual permit under 40 C.F.R. § 122.34, which would again require compliance with the six Minimum Measures. Id. at §§ 122.33(b)(2)®, 122.34(a), 122.34(b). Third, under an “Alternative Permit” option, the small MS4 may apply for an individualized permit under 40 C.F.R. § 122.26(d), the permitting program established by the Phase I Rule for large and medium-sized MS4s. Id. at §§ 122.33(b)(2)(h), 122.26(d).

The Minimum Measures mentioned above require small MS4s to implement programs for: (1) conducting public education and outreach on stormwater impacts, id. at § 122.34(b)(1); (2) engaging public participation in the development of stormwater management programs, id. at § 122.34(b)(2); (3) detecting and eliminating illicit discharges to the MS4, id. at § 122.34(b)(3); (4) reducing pollution to the MS4 from construction activities disturbing one acre or more, id. at § 122.34(b)(4); (5) minimizing water quality impacts from development and redevelopment activities that disturb one acre or more, id. at § 122.34(b)(5); and (6) preventing or reducing pollutant runoff from municipal activities, id. at § 122.34(b)(6).

The Municipal Petitioners contend that the measures regulating illicit discharges, small construction sites, and development activities unconstitutionally compel small MS4 operators to regulate third parties, i.e., upstream dischargers. The Illicit Discharge Detection and Elimination measure requires that a permit seeker prohibit non-stormwater discharges to the MS4 and implement appropriate enforcement procedures. 40 C.F.R. § 122.34(b)(3)(ii)(B). The Construction Site Stormwater Runoff Control measure requires a permit seeker to implement and enforce a program to reduce stormwater pollutants from small construction sites. Id. at §§ 122.34(b)(4)(i)-(ii). It mandates erosion and sedimentation controls, site plan reviews that take account of water quality impacts, site inspections, and the consideration of public comment, and requires that construction site operators implement erosion, sedimentation, and waste management best management practices. Id. The Post-Construction/New Development measure requires permit seekers to address post-construction runoff from new development and redevelopment projects disturbing one acre or more. Id. at § 122.34(b)(5)(ii)(B).

Noting that most MS4s are operated by municipal governments, and that “[t]he drainage of a city in the interest of the public health and welfare is one of the most important purposes for which the police power can be exercised,” New Orleans Gaslight Co. v. Drainage Comm’n, 197 U.S. 453, 460, 25 S.Ct. 471, 49 L.Ed. 831 (1905), the Municipal Petitioners argue that requiring operators of small MS4s to implement “through ordinance or other regulatory mechanism” the regulations required by the Minimum Measures contravenes the Tenth Amendment. See, e.g., New York v. United States, 505 U.S. 144, 188, 112 S.Ct. 2408, 120 L.Ed.2d 120 (1992).

EPA counters that the Phase II Rule does not violate the Tenth Amendment because operators of small MS4s may opt to avoid the Minimum Measures by seeking a permit under the Alternative Permit option, 40 C.F.R. § 122.33(b)(2)(ii).

Under the Tenth Amendment, “the Federal Government may not compel States to implement, by legislation or executive action, federal regulatory programs.” Printz v. United States, 521 U.S. 898, 925, 117 S.Ct. 2365, 138 L.Ed.2d 914 (1997); see also New York, 505 U.S. at 188, 112 S.Ct. 2408. Similarly, the federal government may not force the States to regulate third parties in furtherance of a federal program. See Reno v. Condon, 528 U.S. 141, 151, 120 S.Ct. 666, 145 L.Ed.2d 587 (2000) (upholding a federal statutory scheme because it “does not require the States in their sovereign capacity to regulate their own citizens”). These protections extend to municipalities. See, e.g., Printz 521 U.S. at 931 n. 15, 117 S.Ct. 2365.

However, while the federal government may not compel them to do so, it may encourage States and municipalities to implement federal regulatory programs. See New York, 505 U.S. at 166-68, 112 S.Ct. 2408. For example, the federal government may make certain federal funds available only to those States or municipalities that enact a given regulatory regime. See, e.g., South Dakota v. Dole, 483 U.S. 203, 205-08, 107 S.Ct. 2793, 97 L.Ed.2d 171 (1987) (upholding federal statute conditioning state receipt of federal highway funds on state adoption of minimum drinking age of twenty-one). The crucial proscribed element is coercion; the residents of the State or municipality must retain “the ultimate decision” as to whether or not the State or municipality will comply with the federal regulatory program. New York, 505 U.S. at 168, 112 S.Ct. 2408. However, as long as “the alternative to implementing a federal regulatory program does not offend the Constitution’s guarantees of federalism, the fact that the alternative is difficult, expensive or otherwise unappealing is insufficient to establish a Tenth Amendment violation.” City of Abilene v. EPA 325 F.3d 657, 662 (5th Cir.2003).

With the Phase II Rule, EPA gave the operators of small MS4s a choice: either implement the regulatory program spelled out by the Minimum Measures described at 40 C.F.R. § 122.34(b), or pursue the Alternative Permit option and seek a permit under the Phase I Rule as described at 40 C.F.R. § 122.26(d). Thus, unless § 122.26(d) itself offends the Constitution’s guarantees of federalism, the Phase II Rule does not violate the Tenth Amendment.

Pursuing a permit under the Alternative Permit option does require permit seekers, in their application for a permit to discharge, to propose management programs that address substantive concerns similar to those addressed by the Minimum Measures. See 40 C.F.R. § 122.26(d). However, § 122.26(d) lists the requirements for an application for a permit to discharge, not the requirements of the permit itself. Therefore, nothing in § 122.26(d) requires the operator of an MS4 to implement a federal regulatory program in order to receive a permit to discharge, because nothing in § 122.26(d) specifies the contents of the permit that will result from the application process.

City of Abilene, 325 F.3d 657, provides a helpful illustration. The cities of Abilene and Irving, Texas, have populations between 100,000 and 250,000, and so were required to apply for permits under the Phase I Rule, 40 C.F.R. § 122.26(d). City of Abilene, 325 F.3d at 659-60. Under § 122.26(d) the cities were required to submit proposed stormwater management programs. Id. at 660. They negotiated the terms of those programs with EPA, and EPA eventually presented the cities with proposed management permits that contained conditions requiring the implementation of stormwater regulatory programs, and potentially requiring the regulation of third parties. Id. But, as the Fifth Circuit noted, this did not mean that the cities had no choice but to implement a federal regulatory program. Instead:

The Cities filed comments objecting to those conditions, and negotiations continued until the EPA offered the Cities the option of pursuing numeric end-of-pipe permits, which would have required the Cities to satisfy specific effluent limitations rather than implement management programs. The Cities declined this offer, electing to continue negotiations on the management permits.

Id. The Fifth Circuit rejected the cities’ contention that the resulting permits violated the Tenth Amendment by requiring the cities to regulate third parties according to federal standards. Id. at 661-63. Because the cities chose to pursue the management permits despite the fact that EPA provided them with an option for obtaining permits that would not have involved implementing a management program or regulating third parties, no unconstitutional coercion occurred. Id. at 663. The ultimate decision to implement the federal program remained with the cities.

Any operator of a small MS4 that wishes to avoid the Minimum Measures may seek a permit under § 122.26(d), and, as City of Abilene demonstrates, nothing in § 122.26(d) will compel the operator of a small MS4 to implement a federal regulatory program or regulate third parties, because § 122.26(d) specifies application requirements, not permit requirements. Therefore, by presenting the option of seeking a permit under § 122.26(d), the Phase II Rule avoids any unconstitutional coercion. The Municipal Petitioners’ claim that the Phase II Rule violates the Tenth Amendment therefore fails.

3. The First Amendment and the Minimum Measures

The Municipal Petitioners contend that the Public Education and Illicit Discharge Minimum Measures compel municipalities to deliver EPA’s political message in violation of the First Amendment. The Phase II Rule’s “Public Education and Outreach” Minimum Measure directs regulated small MS4s to “distribute educational materials to the community ... about the impacts of stormwater discharges on water bodies and the steps the public can take to reduce pollutants in stormwater runoff.” 40 C.F.R. § 122.34(b)(l)(i). The “Illicit Discharge Detection and Elimination” measure requires regulated small MS4s to “[ijnform public employees, businesses, and the general public of hazards associated with illegal discharges and improper disposal of waste.” 40 C.F.R. § 122.34(b)(3)(ii)(D).

The Municipal Petitioners argue that the First Amendment prohibits EPA from compelling small MS4s to communicate messages that they might not otherwise wish to deliver. They further contend that EPA’s interpretation of § 402(p) as authorizing these Measures does not warrant Chevron deference because it raises serious constitutional issues, but that even if deference were given, the resulting rule is unconstitutional because neither Congress nor EPA may dictate the speech of MS4s. They contend that municipalities are protected by the First Amendment, Pacific Gas & Elec. v. Public Utilities Comm’n, 475 U.S. 1, 8, 106 S.Ct. 903, 89 L.Ed.2d 1 (1986) (“Corporations and other associations, like individuals, contribute to the [discourse] that the First Amendment seeks to foster.... ”), which applies as much to compelled statements of “fact” as to those of “opinion.” Riley v. Nat’l Fed. of the Blind, 487 U.S. 781, 797-98, 108 S.Ct. 2667, 101 L.Ed.2d 669 (1988).

We conclude that the purpose of the challenged provisions is legitimate and consistent with the regulatory goals of the overall scheme of the Clean Water Act, cf. Glickman v. Wileman Bros. & Elliott, Inc., 521 U.S. 457, 476, 117 S.Ct. 2130, 138 L.Ed.2d 585 (1997), and does not offend the First Amendment. The State may not constitutionally require an individual to disseminate an ideological message, Wooley v. Maynard, 430 U.S. 705, 713, 97 S.Ct. 1428, 51 L.Ed.2d 752 (1977), but requiring a provider of storm sewers that discharge into national waters to educate the public about the impacts of stormwater discharge on water bodies and to inform affected parties, including the public, about the hazards of improper waste disposal falls short of compelling such speech. These broad requirements do not dictate a specific message. They require appropriate educational and public information activities that need not include any specific speech at all. A regulation is facially unconstitutional only when every possible reading compels it, Meinhold v. U.S. Dep’t of Def., 34 F.3d 1469, 1476 (9th Cir.1994), but this is clearly not the case here.

As in Zauderer v. Office of Disciplinary Counsel of the Sup. Ct. of Ohio, 471 U.S. 626, 105 S.Ct. 2265, 85 L.Ed.2d 652 (1985), where the Supreme Court upheld certain disclosure requirements in attorney advertising, “[t]he interests at stake in this case are not of the same order as those discussed in Wooley [invalidating a law requiring that drivers display the motto ‘Live Free or Die’ on New Hampshire license plates] ... and Barnette [forbidding the requirement that public school students salute the flag because the State may not impose on the individual ‘a ceremony so touching matters of opinion and political attitude’].” Id. at 651. EPA has not attempted to “prescribe what shall be orthodox in politics, nationalism, religion, or other matters of opinion or force citizens to confess by word or act their faith therein.” West Virginia State Bd. of Ed. v. Barnette, 319 U.S. 624, 642, 63 S.Ct. 1178, 87 L.Ed. 1628 (1943).

Informing the public about safe toxin disposal is non-ideological; it involves no “compelled recitation of a message” and no “affirmation of belief.” PruneYard Shopping Ctr. v. Robins, 447 U.S. 74, 88, 100 S.Ct. 2035, 64 L.Ed.2d 741 (1980) (upholding state law protecting petitioning in malls and noting that “Barnette is inappo-site because it involved the compelled recitation of a message containing an affirmation of belief’). It does not prohibit the MS4 from stating its own views about the proper means of managing toxic materials, or even about the Phase II Rule itself. Nor is the MS4'prevented from identifying its dissemination of public information as required by federal law, or from making available federally produced informational materials on the subject and identifying them as such.

Even if such a loosely defined public information requirement could be read as compelling speech, the regulation resembles another regulation that the Supreme Court has held permissible. In Glickman, 521 U.S. 457, 117 S.Ct. 2130, 138 L.Ed.2d 585, the Court upheld a generic advertising assessment promulgated by the Department of Agriculture on behalf of California tree fruit growers because the order was consistent with an overall regulatory program that did not abridge protected speech:

Three characteristics of the regulatory scheme at issue distinguish it from laws that we have found to abridge the freedom of speech protected by the First Amendment. First, the marketing orders impose no restraint on the freedom of any producer to communicate any message to any audience. Second, they do not compel any person to engage in any actual or symbolic speech. Third, they do not compel the producers to endorse or to finance any political or ideological views. Indeed, since all of the respondents are engaged in the business of marketing California nectarines, plums, and peaches, it is fair to presume that they agree with the central message of the speech that is generated by the generic program.

Id. at 469-70, 117 S.Ct. 2130 (footnotes omitted). Here, as in Glickman, the Phase II regulations impose no restraint on the freedom of any MS4 to communicate any message to any audience. They do not compel any specific speech, nor do they compel endorsement of political or ideological views. And since all permittees are engaged in the handling of stormwater runoff that must be conveyed in reasonably unpolluted form to national waters, it is similarly fair to presume that they will agree with the central message of a public safety alert encouraging proper disposal of toxic materials. The Phase II regulation departs only from the second element in the Glickman analysis, because the public information requirement may compel a regulated party to engage in some speech at some time; but unlike the offensive messages in Maynard and Barnette (and even the inoffensive advertising messages at issue in Glickmari) that speech is not specified by the regulation.

The public information requirement does not impermissibly compel speech, and nothing else in the Phase II Rule offends the First Amendment. The Rule does not compel a recitation of a specific message, let alone an affirmation of belief. To the extent MS4s are regulated by the public information requirement, the regulation is consistent with the overall regulatory program of the Clean Water Act and the responsibilities of point source dischargers.

4. Notice and Comment on the Alternative Permit Option

The Municipal Petitioners contend that, in adopting the Alternative Permit option, EPA. did not comply with the minimum notice and comment procedures required in informal rulemaking by the Administrative Procedures Act (“APA”), 5 U.S.C. § 558. The APA requires an agency to publish notice of a proposed rulemaking that includes “either the terms or substance of the proposed rule or a description of the subjects and issues involved.” Id. at § 553(b)(3).

We have held that a “final regulation that varies from the proposal, even substantially, will be valid as long as it is ‘in character with the original proposal and a logical outgrowth of the notice and comments.’ ” Hodge v. Dalton, 107 F.3d 705, 712 (9th Cir.1997). In determining whether notice was adequate, we consider whether the complaining party should have anticipated that a particular requirement might be imposed. The test is whether a new round of notice and comment would provide the first opportunity for interested parties to offer comments that could persuade the agency to modify its rule. Am. Water Works Ass’n v. EPA 40 F.3d 1266, 1274 (D.C.Cir.1994).

The Municipal Petitioners argue that the Alternative Permit option is not a logical outgrowth of EPA’s proposed rule because, although numerous alternatives were discussed in the Preamble to the proposed rule, 63 Fed. Reg. at 1554-1557, the Alternative Permit option eventually adopted was not. EPA counters that the proposed rule included a supplementary alternative permitting system based on concepts similar to those in the Minimum Measures, including “simplified individual permit application requirements.” EPA contends that the Alternative Permit option was a logical outgrowth of the comments it received on the proposal expressing concern that the Minimum Measures might violate the Tenth Amendment. 64 Fed. Reg. at 68,765.

The Alternative Permit option passes the Hodge test. The proposed rule suggested an individualized permitting option to be developed in response to comments during the notice and comment period. The Alternative option contains no elements that were not part of the original rule, even if they are configured differently in the final rule. Petitioners had, and took, their opportunity to object to the aspects of the Rule that they did not support in their comments on the Minimum Measures.

B. The General Permit Option and Notices of Intent

The Environmental Petitioners contend that the general permitting scheme of the Phase II Rule allows regulated small MS4s to design stormwater pollution control programs without adequate regulatory and public oversight, and that it contravenes the Clean Water Act because it does not require EPA to review' the content of dis-chargers’ notices of intent and does not contain express requirements for public participation in the NPDES' permitting process.

In reviewing a federal administrative agency’s interpretation of a statute it administers, we first determine whether Congress has expressed its intent unambiguously on the question before the court. See Chevron, 467 U.S. 837, 842-44, 104 S.Ct. 2778, 81 L.Ed.2d 694 (“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.”). “If, instead, Congress has left a gap for the administrative agency to fill, we proceed to step two. At step two, we must uphold the administrative regulation unless it is arbitrary, capricious, or manifestly contrary to the statute.” Defenders of Wildlife v. Browner, 191 F.3d 1159, 1162, amended by 197 F.3d 1035 (9th Cir.1999) (citations and internal quotations omitted).

We conclude that the Phase II General Permit option violates the Clean Water Act’s requirement that permits for discharges “require controls to reduce the discharge of pollutants to the maximum extent practicable,” 33 U.S.C. § 1342(p)(3)(B)(iii). We also conclude that the Phase II General Permit option violates the Clean Water Act because it does not contain express requirements for public participation in the NPDES permitting process. We remand these aspects of the Phase II Rule.

1. Phase II General Permits and Notices of Intent

Primary responsibility for enforcement of the requirements of the Clean Water Act is vested in the Administrator of the EPA. 33 U.S.C. § 1251(d); see also 33 U.S.C. § 1361(a) (“The Administrator [of EPA] is authorized to prescribe such regulations as are necessary to carry out his functions under this chapter”). The Clean Water Act renders illegal any discharge of pollutants not specifically authorized by a permit. 33 U.S.C. § 1311(a) (“Except in compliance with this section and [other sections detailing permitting requirements] of this title, the discharge of any pollutant by any person shall be unlawful”). Under the Phase II Rule, dischar-gers may apply for an individualized permit with the relevant permitting authority, or may file a “Notice of Intent” (“NOI”) to seek coverage under a “general permit.” 40 C.F.R. § 122.33(b).

A general permit is a tool by which EPA regulates a large number of similar dis-chargers. Under the traditional general permitting model, each general permit identifies the output limitations and technology-based requirements necessary to adequately protect water quality from a class of dischargers. Those dischargers may then acquire permission to discharge under the Clean Water Act by filing NOIs, which embody each discharger’s agreement to abide by the terms of the general permit. Because the NOI represents no more than a formal acceptance of terms elaborated elsewhere, EPA’s approach does not require that permitting authorities review an NOI before the party who submitted the NOI is allowed to discharge. General permitting has long been recognized as a lawful means of authorizing discharges. Natural Res. Def. Council v. Costle, 568 F.2d 1369 (D.C.Cir.1977).

The Phase II general permitting scheme differs from the traditional general permitting model. The Clean Water Act requires EPA to ensure that operators of small MS4s “reduce the discharge of pollutants to the maximum extent practicable.” 33 U.S.C. § 1342(p)(3)(B). To ensure that operators of small MS4s achieve this “maximum extent practicable” standard, the Phase II Rule requires that each NOI contain information on an individualized pollution control program that addresses each of the six general criteria specified in the Minimum Measures; thus, according to the Phase II Rule, submitting an NOI and implementing the Minimum Measures it contains “constitutes compliance with the standard of reducing pollutants to the ‘maximum extent practicable.’ ” 40 C.F.R. § 122.34(a).

Because a Phase II NOI establishes what the discharger will do to reduce discharges to the “maximum extent practicable,” the Phase II NOI crosses the threshold from being an item of procedural correspondence to being a substantive component of a regulatory regime. The text of the Rule itself acknowledges that a Phase II NOI is a permit application that is, at least in some regards, functionally equivalent to a detailed application for an individualized permit. See, e.g., 40 C.F.R. § 122.34(d)(1) (“In your permit application (either a notice of intent for coverage under a general permit or an individual permit application), you must identify and submit to your NPDES permitting authority the following information-”). For this reason, EPA rejected the possibility of providing a “form NOI” to Phase II permittees, explaining that “[w]hat will be required on an MS4’s NOI ... is more extensive than what is usually required on an NOI, so a ‘form’ NOI for MS4s may be impractical.” 64 Fed. Reg. at 68,764.

2. Failure to Regulate

The Environmental Petitioners argue that, by allowing NPDES authorities to grant dischargers permits based on unre-viewed NOIs, the Rule creates an impermissible self-regulatory system. Petitioners contend the Rule impermissibly fails to require that the permitting authority review an NOI to assure compliance with Clean Water Act standards, including the standard that municipal stormwater pollution be reduced to “the maximum extent practicable.” 33 U.S.C. § 1342(p)(3)(B)(iii). See 40 C.F.R. § 123.35 (setting out requirements for permitting authorities, but not requiring review of NOI); 64 Fed. Reg. at 68,764 (“EPA disagrees that formal approval or disapproval by the permitting authority is needed”).

EPA maintains that the Phase II permit system is fully consistent with the authorizing statute. It contends that § 402(p)(6) granted EPA flexibility in designing the Phase II “comprehensive program,” and notes that while the statute does not require general permits, neither does it preclude them. EPA contends that Congress delegated the task of designing the program to EPA, and that EPA reasonably adopted a “flexible version” of the NPDES permit program to suit the unique needs of the Phase II program. It disputes. that the general permit program creates “paper tigers,” especially since EPA, States, and citizens may initiate enforcement actions. Finally, EPA argues that the Rule does not create a self-regulatory program, but that even if it did, nothing in § 402(p)(6) precludes such a program.

Reviewing-the Phase II Rule under the first step of Chevron, we note that the plain language of § 402(p) of the Clean Water Act, 33 U.S.C. § 1342(p), expresses unambiguously Congress’s intent that EPA issue no permits to discharge from municipal storm sewers unless those permits “require controls to reduce the discharge of pollutants to the maximum extent practicable.”

Phase II general permits will likely impose requirements that ensure that operators of small MS4s comply with many of the standards of the Clean Water Act. Thus, general permits issued under Phase II will ordinarily contain numerous substantive requirements, just as did the permits issued under Phase I. See 40 C.F.R. §§ 123.35 & 123.35(a) (“§ 123.35 As the NPDES Permitting Authority for regulated small MS4s, what is my role? (a) You must comply with the requirements for all NPDES permitting authorities under Parts 122, 123, 124 and 125 of this chapter.”); see also 40 C.F.R. § 122.28 (outlining requirements for NPDES authorities issuing general permits). And every operator of a small MS4 who files an NOI under Phase II “must comply with other applicable NPDES permit requirements, standards, and conditions established in the ... general permit.” See 40 C.F.R. §§ 122.34 & 122.34(f).

However, while each Phase II general permit will likely ensure that operators of small MS4s comply with certain standards of the Clean Water Act, they will not “require controls to reduce the discharge of pollutants to the maximum extent practicable.” According to the Phase II Rule, the operator of a small MS4 has complied with the requirement of reducing discharges to the “maximum .extent practicable” when it implements its stormwater management program, i.e., when it implements its Minimum Measures. 40 C.F.R. § 122.34(a); see also 64 Fed. Reg. at 68753 (stating EPA’s anticipation that limitations more stringent that thé minimum control measures, “will be unnecessary”). Nothing in the Phase II regulations requires that NPDES permitting authorities review these Minimum Measures to ensure that the measures that any given operator of a small MS4 has decided to undertake will in fact reduce discharges to the maximum extent practicable.

See 40 C.F.R. § 123.35 (“As the NPDES Permitting Authority for regulated small MS4s, what is my role?”). Therefore, under the Phase II Rule, nothing prevents the operator of a small MS4 from misunderstanding or misrepresenting its own stormwater situation and proposing a set of minimum measures for itself that would reduce discharges by far less than the maximum extent practicable.

In fact, under the Phase II Rule, in order to receive the protection of a general permit, the operator of a small MS4 needs to do nothing more than decide for itself what reduction in discharges would be the maximum practical reduction. No one will review that operator’s decision to make sure that it was reasonable, or even good faith. Therefore, as the Phase II Rule stands, EPA would allow permits to issue that would do less than require controls to reduce the discharge of pollutants to the maximum extent practicable. See 64 Fed. Reg. at 68753 (explaining that the minimum control measures will protect water quality if they are “properly implemented”). We therefore must reject this aspect of the Phase II Rule as contrary to the clear intent of Congress. Cf. Natural Res. Def. Council, 966 F.2d at 1305 (rejecting as arbitrary and capricious a permitting system that allowed regulated industrial stormwater dischargers to “self-report” whether they needed permit coverage).

Involving regulated parties in the development of individualized stormwater pollution control programs is a laudable step consistent with the directive to consult with state and local authorities in the development of the § 402(p)(6) comprehensive program. But EPA is still required to ensure that the individual programs adopted are consistent with the law. Our holding should not prevent the Phase II general permitting program from proceeding mostly as planned. Our holding does not preclude regulated parties from designing aspects of their own stormwater management programs, as contemplated under the Phase II Rule. However, storm-water management programs that are designed by regulated parties must, in every instance, be subject to meaningful review by an appropriate regulating entity to ensure that each such program reduces the discharge of pollutants to the maximum extent practicable. We therefore remand this aspect of the Rule.

3. Public Participation

The Environmental Petitioners contend that the Phase II Rule fails to provide for public participation as required by the Clean Water Act, because the public receives neither notice nor opportunity for hearing regarding an NOI. The EPA replies on the one hand by arguing that NOIs are not “permits” and therefore are not subject to the public availability and public hearing requirements of the Clean Water Act, and on the other hand by arguing that the combination of the public involvement minimum measure, 40 C.F.R. § 122.34(b)(2), the Federal Freedom of Information Act, 5 U.S.C. § 552, and state freedom of information acts would fulfill any such requirements if NOIs were permits.

Reviewing the Phase II Rule under Chevron step one, we conclude that clear Congressional intent requires that NOIs be subject to the Clean Water Act’s public availability and public hearings requirements. The Clean Water Act requires that “[a] copy of each permit application and each permit issued under [the NPDES permitting program] shall be available to the public,” 33 U.S.C. § 1342(j), and that the public shall have an opportunity for a hearing before an permit application is approved, 33 U.S.C. § 1342(a)(1). Congress identified public participation rights as a critical means of advancing the goals of the Clean Water Act in its primary statement of the Act’s approach and philosophy. See 33 U.S.C. § 1251(e); see also Costle v. Pacific Legal Found., 445 U.S. 198, 216, 100 S.Ct. 1095, 63 L.Ed.2d 329 (1980) (noting the “general policy of encouraging public participation is applicable to the administration of the NPDES permit program”). EPA has acknowledged that technical issues relating to the issuance of NPDES permits should be decided in “the most open, accessible forum possible, and at a stage where the [permitting authority] has the greatest flexibility to make appropriate modifications to the permit.” 44 Fed. Reg. 32,854, 32,885 (June 7, 1979).

As we noted above, under the Phase II Rule it is the NOIs, and not the general permits, that contain the substantive information about how the operator of a small MS4 will reduce discharges to the maximum extent practicable. Under the Phase II Rule, NOIs are functionally equivalent to the permit applications Congress envisioned when it created the Clean Water Act’s public availability and public hearing requirements. Thus, if the Phase II Rule does not make NOIs “available to the public,” and does not provide for public hearings on NOIs, the Phase II Rule violates the clear intent of Congress. EPA’s first argument — that NOIs are not subject to the public availability and public hearings requirements of the Clean Water Act— therefore fails.

We therefore reject the Phase II Rule as contrary to the clear intent of Congress insofar as it does not provide for public hearings on NOIs as required by 33 U.S.C. § 1342(a)(1). However, Congress has not directly addressed the question of what would constitute an NOI being “available to the public” as required by 33 U.S.C. § 1342(j). Under Chevron step two, we must defer to EPA’s interpretation of “available to the public” unless it is arbitrary, capricious, or manifestly contrary to the statute.

EPA argues that the NOIs are “available to the public” as a result of the combined effects of the public participation minimum measures, and of federal and state freedom of information acts. This argument is unconvincing. First, the public participation Minimum Measure only requires dischargers to design a program minimally consistent with State, Tribal, and local requirements. 40 C.F.R. § 122.34(b)(2). Second, the federal Freedom of Information Act only applies to documents that are actually in EPA’s possession, not to documents that are in the possession of state or tribal NPDES authorities, see 40 C.F.R. § 2 (providing EPA’s policy for releasing documents under the federal Freedom of Information Act), and nothing in the Phase II Rule provides that EPA obtain possession of every NOI that is submitted to a NPDES permitting authority. See 40 C.F.R. § 123.41(a) (making information provided to state NPDES authorities available to EPA only upon request). Thus, under the Phase II Rule, NOIs will only “be available to the public” subject to the vagaries of state and local freedom of information acts. We conclude that EPA’s interpretation of 33 U.S.C. § 1342(j), as embodied in the provisions of the Phase II Rule providing for the public availability of NOIs, is manifestly contrary to the Clean Water Act, which contemplates greater scope, greater certainty, and greater uniformity of public availability than the Phase II Rule provides. We therefore reject this aspect of the Phase II Rule.

In sum, we conclude that EPA’s failure to require review of NOIs, which are the functional equivalents of permits under the Phase II General Permit option, and EPA’s failure to make NOIs available to the public or subject to public hearings contravene the express requirements of the Clean Water Act. We therefore vacate those portions of the Phase II Rule that address these procedural issues relating to the issuance of NOIs under the Small MS4 General Permit option, and remand so that EPA may take appropriate action to comply with the Clean Water Act.

C. Failure to Designate

We reject the Environmental Petitioners’ contention that EPA’s failure to designate for Phase II regulation serious sources of stormwater pollution, including certain industrial (“Group A”) sources and forest roads, was arbitrary and capricious. See Marsh v. Oregon Natural Res. Council, 490 U.S. 360, 378, 109 S.Ct. 1851, 104 L.Ed.2d 377 (1989).

1. “Group A ” Facilities

In addition to the small MS4s and construction sites ultimately designated for regulation under the Phase II Rule, EPA evaluated a variety of other point-source discharge categories for potential Phase II regulation. One group of dischargers (referred to as the “Group A” facilities) included sources that “are very similar, or identical” to regulated stormwater discharges associated with industrial activity that were not designated for Phase I regulation for administrative reasons unrelated to their environmental impacts. 64 Fed. Reg. at 68,779. EPA estimates that Group A includes approximately 100,000 facilities, including auxiliary facilities and secondary activities (“e.g., maintenance of construction equipment and vehicles, local trucking for an unregulated facility such as a grocery store,” id.) and facilities intentionally omitted from Phase I designation (“e.g., publicly owned treatment works with a design flow of less than 1 million gallons per day, landfills that have not received industrial waste,” id.).

The Environmental Petitioners contend that EPA should have designated the Group A facilities for categorical Phase II regulation after finding (1) that stormwa-ter discharges from these facilities are the same as those from the industrial sources regulated under Phase I, and (2) that such discharges may cause “adverse water quality impacts.” Id. Petitioners argue that these findings, and EPA’s failure to provide individualized analysis regarding whether any specific source category within Group A requires regulation, render EPA’s decision not to regulate any of these sources under the Rule arbitrary and capricious. They maintain that EPA’s “line-drawing,” which regulates some pollution sources but leaves nearly identical sources unregulated without any persuasive rationale, is necessarily arbitrary and capricious. See Natural Res. Def. Council, 966 F.2d at 1306 (EPA’s decision not to regulate construction sites smaller than five acres was arbitrary when EPA provided no data to justify the five-acre threshold and admitted that unregulated sites could have significant water quality impacts).

Petitioners argue that § 402(p)(6) at least required EPA to make findings with respect to individual Group A categories, and that data collected from Phase I permit applications could be used to evaluate the pollutant potential of the identical Group A sources. They contend that these findings should have sufficed as a basis for designating at least some Group A sources, and that EPA’s conclusion that it lacked adequate nationwide data upon which to designate any of these sources is not supported by the record evidence. Comparing EPA’s identification of the serious polluting potential of some of these sources with its statutory mandate under § 402(p)(6) “to protect water quality,” they argue that EPA fails even the forgiving standard of arbitrary and capricious review in that it has “offered an explanation for its decision that runs counter to the evidence before [it]” and “is so implausible that it could not be ascribed to a difference in view or the product of agency expertise.” See Motor Vehicle Mfrs., 463 U.S. at 43, 103 S.Ct. 2866.

EPA maintains that it considered Group A facilities’ similarity to already regulated sources as only one of several criteria that it used in designating sources for regulation under Phase II, 64 Fed. Reg. at 68,-780, and that sources that appear “similarly situated” under one criterion are not necessarily similarly situated under all. EPA asserts that nothing in § 402(p)(6) implied a responsibility to make individualized findings regarding each Group A subcategory, and it maintains that it simply lacked sufficient data to support nationwide designation of the Group A facilities. EPA notes that, after failing to receive requested comment providing such data, it proposed instead “to protect water quality” by allowing regional regulation of problem Group A facilities under the residual designation authority. EPA contends that agencies must be afforded deference in determining the data necessary to support regulatory decisionmaking and that it reasonably determined the quantum of data it would need to support the designation of additional sources on a nationwide basis. See Sierra Club v. EPA, 167 F.3d 658, 662 (D.C.Cir.1999).

We conclude that sufficient evidence supports EPA’s decision not to designate Group A sources on a nationwide basis, and instead to establish local and regional designation authority to account for these sources and protect water quality. Although we are troubled by the purely administrative basis for the distinction between facilities regulated under the Phase I Rule and the Group A facilities that remain unregulated under Phase II, EPA’s choice of the Phase I standard for designation is not the issue before us. Before us is whether EPA acted arbitrarily in declining to designate the Group A sources on a nationwide basis under the Phase II Rule, and we cannot say that it did.

EPA has articulated a rational connection between record facts indicating insufficient data to categorically regulate Group A facilities and its corresponding conclusion not to do so, and we defer to that decision. See Washington v. Daley, 173 F.3d 1158, 1169 (9th Cir.1999). In the text of the Rule, EPA explains that the process behind its decision not to nationally designate Group A sources for Phase II regulation focused not only on the likelihood of contamination from a source category, but also on the sufficiency of national data about each category and whether pollution concerns were adequately addressed by existing environmental regulations. We cannot say that EPA relied on factors Congress had not intended it to consider, that it failed to consider an important aspect of the problem, or that its rationale is implausible. See Motor Vehicle Mfrs., 463 U.S. at 43, 103 S.Ct. 2856. Nor did EPA’s decision run counter to the evidence before it. Id. The Environmental Petitioners allege that its decision not to regulate Group A facilities runs counter to evidence that similar sources are highly polluting, but as EPA considered evidence beyond those similarities that persuaded it not to regulate, we cannot say that EPA’s decision is unsupported by the record. Nothing in § 402(p)(6) unambiguously requires EPA to evaluate the Group A source categories individually, and we defer to EPA’s interpretation of the statute it is charged with administering. See Royal Foods Co. v. RJR Holdings, 252 F.3d 1102, 1106 (9th Cir.2001).

2. Forest Roads

The Environmental Petitioners also contend that EPA arbitrarily failed to regulate forest roads under the Rule despite clear evidence in the record documenting the need for stormwater pollution control of drainage from these roads. Petitioners again contend that this agency action is arbitrary, because EPA has offered an explanation for its decision that runs counter to the evidence before it.

Petitioners point to EPA’s own conclusion that forest roads “are considered to be the major source of erosion from forested lands, contributing up to 90 percent of the total sediment production from forestry operations.” They note that both unimproved forest roads and construction sites create large expanses of non-vegetated soil subject to stormwater erosion, and argue that construction site data thus also support regulation of forest roads. Petitioners observe that EPA has cited no contrary evidence indicating that forest roads are not sources of stormwater pollutant discharges to U.S. waters, and they argue that Phase II regulation is necessary “to protect water quality,” because proper planning and road design can minimize erosion and prevent stream sedimentation. Petitioners note that this court has previously held that, in the absence of such “supportable facts,” EPA is not entitled to the usual assumption that it has “rationally exercised the duties delegated to it by Congress.” Natural Res. Def. Council, 966 F.2d at 1305.

EPA’s response is that we have no jurisdiction to hear this challenge, chiefly because, it believes, the challenge is time-barred by Clean Water Act § 509(b)(1), 33 U.S.C. § 1369(b)(1) (providing that “application for review shall be made within 120 days from the date of [agency action]”). EPA promulgated silviculture regulations in 1976 that exclude from NPDES permit requirements certain silvicultural activities that EPA determined constitute non-point source activities, including “surface drainage, or road construction and maintenance from which there is natural runoff.” 40 C.F.R. § 122.27(b)(1). EPA asserts that the exclusion applies to forest roads in general, not only to “construction” and “maintenance” — an assertion disputed by Petitioners — and that any challenge to the decision not to regulate forest roads should have been brought within 120 days of the promulgation of that rule. See 33 U.S.C. § 1369(b)(1).

EPA’s argument might be more persuasive if Petitioners’ contention could be understood essentially as a direct challenge to the 1976 silviculture regulations, but this is not the case. Even were we to assume that EPA exempted forest roads from NPDES permit requirements in 1976 under 40 C.F.R. § 122.27(b)(1), that would not resolve the question whether EPA should have addressed forest roads in its “comprehensive program ... to protect water quality” under § 402(p)(6), because § 402(p)(6) was not enacted until 1987. Petitioners challenge EPA’s decision not to regulate under the new portion of the statute, not the decision not to regulate under other provisions that were in effect earlier.

EPA argues in the alternative that Petitioners should have sought judicial review when EPA considered amending § 122.27(b)(1) — to delete the language that it asserts renders forest roads non-point sources — but then determined not to make the amendment. However, we are aware of no statute or legal doctrine providing that a party’s failure to challenge an agency’s decision not to amend its rules in one proceeding deprives the party of the right to challenge, in a contemporaneous proceeding, the promulgation of an entire new rule which could have, but did not, provide the full relief the party seeks. Assuming that EPA is correct that § 122.27(b)(1) defines forest roads as non-point sources, both the Phase II Rule proceedings and the proceedings in which the proposed amendment to § 122.27(b)(1) was considered and rejected were proper proceedings in which to raise the issue whether discharges from forest roads should be regulated. Petitioners chose to raise the issue in their comments to the proposed Phase II Rule, because they believed that Clean Water Act § 402(p)(6) mandates the regulation of forest roads. They did not lose their right to challenge the final Phase II Rule’s failure to regulate forest roads simply because they did not also raise a challenge to EPA’s failure to adopt an amendment to § 122.27(b)(1) that the agency initially proposed. (We note, incidentally, that it appears that even a successful challenge to § 122.27(b)(1) would likely not have achieved the objective the Environmental Petitioners sought: it would only have allowed case-by-case coverage for forest roads, and not for overall coverage.)

Finally, EPA suggests that Petitioners’ comments during the Phase II rulemaking process were too short to create jurisdiction in this court to hear this challenge. However, EPA exaggerates the slightness of those comments, which comprised two paragraphs, with footnotes, stating objections and providing support. We also agree with Petitioners that EPA was aware of the forest road sedimentation problem at the time of the rulemak-ing. Indeed, EPA responded to the comments without disputing that the problem is serious. 3 EPA, Response to Public Comments 8 (Oct. 29, 1999). Rather, the agency relied on 40 C.F.R. § 122.27(b)(1), indicating that it was barred from acting under the Phase II Rule by § 122.27(b)(1).

EPA does not seriously address the merits of Petitioners’ objections to the Rule in its brief to this court. Instead, EPA relies almost entirely on its assertion that we lack jurisdiction to decide this question. It does, however, strongly imply that its failure to adopt its own proposed amendment in the proceeding pertaining to § 122.27(b)(1) relieves it of its obligation to consider including forest roads in the Phase II Rule proceedings. We reject any such contention. Petitioners’ assertion that § 402(p)(6) requires that the Phase II Rule contain provisions regulating forest roads necessitates a response from EPA on the merits.

Having concluded that the objections of the Environmental Petitioners are not time-barred, and that we have jurisdiction to hear them, but that EPA failed to consider those objections on the merits, we remand this issue to the EPA, so that it may consider in an appropriate proceeding Petitioners’ contention that § 402(p)(6) requires EPA to regulate forest roads. EPA may then either accept Petitioners’ arguments in whole or in part, or reject them on the basis of valid reasons that are adequately set forth to permit judicial review.

D. AF&PA’s Standing

The American Forestry & Paper Association (AF&PA), a national trade association representing the forest, pulp, paperboard, and wood products industry, is one of the two Industry Petitioners asserting the remaining claims. Before considering these challenges, however, we consider whether AF&PA has standing to raise them.

EPA argues that AF&PA lacks standing because it cannot show that it represents entities that suffer a cognizable injury under the Phase II Rule as promulgated. EPA argues that the interests of AF&PA entities might have supported standing had EPA decided to regulate forest roads as Phase II stormwater dischargers, but since EPA declined to do so, none of AF&PA’s members are currently subject to the Rule. AF&PA contends that its members have a cognizable legal interest in the Rule because they risk becoming subject to regulation at any future time under the continuing designation authority.

We agree that AF&PA lacks standing. A claimant meeting Article III standing requirements must show that “(1) it has suffered an ‘injury in fact’ ...; (2) the injury is fairly traceable to the challenged action of the defendant; and (3) it is likely, as opposed to merely speculative, that the injury will be redressed by a favorable decision.” Friends of the Earth v. Laidlaw Envtl. Servs. (TOC), 528 U.S. 167, 180-81, 120 S.Ct. 693, 145 L.Ed.2d 610 (2000). Standing requires an injury that is “actual or imminent, not ‘conjectural or hypothetical.’” Lujan v. Defenders of Wildlife, 504 U.S. 555, 560, 112 S.Ct. 2130, 119 L.Ed.2d 351 (1992). AF&PA’s interest in avoiding future regulation of forest roads is not actually or imminently threatened by any potential result in this case. No ripe claim about misuse of the residual authority to regulate forest road discharge, or any other kind of discharge, is before the court. Should members of AF&PA become subject to Phase II regulation through subsequent administrative action, it will have standing to challenge those actions at that time. In the meanwhile, we proceed to the merits of the remaining claims on behalf of AF&PA’s co-petitioner, the National Association of Home Builders, which has established its standing to raise them.

E. Consultation with State and Local Officials

The Industry Petitioners contend that EPA failed to consult with the States on the Phase II Rule as required by § 402(p)(5), which instructs EPA to conduct studies “in consultation with the States,” and § 402(p)(6), which instructs the Administrator to issue regulations based on these studies “in consultation with State and local officials.” 33 U.S.C. §§ 1342(p)(5)-(6). We conclude that EPA satisfied its statutory duty of consultation. See Marsh, 490 U.S. at 378, 109 S.Ct. 1851.

Petitioners concede several instances in which EPA circulated drafts of the Phase II Rule to state and local authorities, but argue that these consultations were meaningless because (1) the reports were circulated too far in advance of the actual rule-making, (2) the rulemaking wrongfully proceeded based on other sources of input, (3) standard APA notice and comment procedures could not suffice because Congress must have intended something more when it added the consultation requirements to the language of § 402, and (4) consultation at the final stage of rulemaking was inadequate because comment was sought on the final report only after it had been submitted to Congress and the Phase II Rule had been promulgated. Petitioners provide examples of state feedback that allegedly went unheeded by EPA in its promulgation of the final Rule.

EPA maintains that it consulted extensively with States and localities in developing the Phase II Rule, discharging its obligations under §§ 402(p)(5) & (6). EPA contends that the comments Petitioners cite as unheeded by EPA demonstrate that EPA did consult with States concerning the Rule, even if some States did not concur in EPA’s ultimate conclusion, and that the final rule adopted a good measure of the flexibility sought by state representatives. EPA argues that Industry Petitioners cannot complain that consultation was inadequate simply because it did not result in the adoption of Petitioners’ preferred views.

EPA also disputes Petitioners’ allegation that while EPA did comply with the terms of the 1999 Appropriations Act (requiring EPA to defend the proposed Phase II Rule before Congress and then publish the final report for public comment), it demonstrated its failure to adequately consult by publishing the report for public comment after the Phase II Rule had been formally promulgated, rendering any subsequent public comment meaningless. EPA counters that these actions do not indicate that it failed to satisfy Congress’s directive that it consult with state and local officials, because EPA had engaged in extensive consultation before Congress requested the Appropriations Act report, and Congress did not require further consultation when it conditioned promulgation of the Rule only on the submission of this final report. EPA claims that while Congress required it to publish the report after its submission, public comment on the report was not required before promulgation, and that the statutory deadline structure rendered any other interpretation impossible.

We conclude that the overall record indicates EPA met its statutory duty of consultation. A draft of the first report was circulated to States, EPA regional offices, the Association of State and Interstate Water Pollution Control Administrators (“ASIWPCA”), and other stakeholders in November, 1993, and was revised based on comments received. EPA established the Urban Wet Weather Flows Federal Advisory Committee (“FACA Committee”), balancing membership between EPA’s various outside stakeholder interests, including representatives from States, municipalities, Tribes, commercial and industrial sectors, agriculture, and environmental and public interest groups. 64 Fed. Reg. 68,724. The 32 members of the Phase II FACA Subcommittee, reflecting the same balance of interests, met fourteen times over three years and state and municipal representatives provided substantial input regarding the draft reports, the ultimate Phase II Rule, and the supporting data. Id. EPA instituted the Phase II Subcommittee meetings in addition to the standard APA notice and comment procedures, which EPA also followed.

The fact that the Rule did not conform to Petitioners’ hopes and expectations does not bear on whether EPA adequately consulted state and local officials. Although required to consult with States and localities, EPA was free to chart the substantive course it saw fit. EPA was not required to consult with States on the Appropriations Act report. Even if EPA should have sought further comment at that late stage, failure to do so does not outweigh the evidence demonstrating extensive consultation and cooperation with local authorities on development of the Rule.

F. Designation of Certain Small MS4s and Construction Sites

The Industry Petitioners contend that, in designating certain small MS4s and construction sites for regulation under the Phase II Rule, EPA failed to adhere to the statutorily required regulatory basis and misinterpreted record evidence. We disagree.

1. Regulatory Basis

The Industry Petitioners and the Municipal Petitioners contend that EPA violated the statutory command to base the Phase II regulations on § 402(p)(5) studies. We review EPA’s interpretation of its statutory authority under the Chevron standard, 467 U.S. at 842-44, 104 S.Ct. 2778, and affirm.

Petitioners argue that the studies mandated by § 402(p)(5) were intended to provide the sole substantive basis for the “comprehensive program” envisioned in § 402(p)(6), but that EPA also (and thus improperly) based its designation of small MS4s and construction sites on (1) public comment received in the aftermath of judicial invalidation of the scope of construction sites regulated by the Phase I Rule, and (2) additional research discussed in the Preamble to the Phase II Rule.

EPA contends that the statute did not require it to base its designations exclusively on the § 402(p)(5) studies, and that it was in fact required to take account of information from other sources in promulgating the regulations. It argues that it based the Phase II Rule on conclusions reported in the § 402(p)(5) studies, but then appropriately supported these results with data described in the additional study requested by Congress in the Appropriations Act, comments submitted during the statutorily required notice-and-comment process, and other available information. To read the authorizing statute as limiting reliance to the § 402(p)(5) studies, EPA claims, would preclude it from relying on recommendations received through the separate, post-study requirement to “consult with State and local officials” under § 402(p)(6), and through the notice and comment process mandated by the APA, 5 U.S.C. § 553(b).

Respondent-intervenor NRDC adds that the Phase II Rule is consistent with the § 402(p)(5) studies reported in 1995, and moreover, that the Industry Petitioners lack standing to raise the “regulatory basis” claim because they cannot show the requisite injury. See Friends of the Earth, 528 U.S. at 180-81, 120 S.Ct. 693.

a. Standing. Industry Petitioners contend that they have suffered injury in fact, because their members are now either automatically regulated by the permitting requirements or subject to future regulation (under the residual authority, discussed below) that otherwise would not have been authorized, and that this is a direct result of EPA’s failure to adhere to the framework of the 1995 Report, which allegedly would have precluded these aspects of .the Rule. NRDC contends that the Industry Petitioners lack standing because they cannot show that being subject to NPDES permitting is the causal result of the procedural injury they urge, and because they cannot base standing on hypothetical injury that may arise in the future.

NRDC argues that the injuries Petitioners allege are not consistent with the guidelines laid out in Friends of the Earth, 528 U.S. at 180-81, 120 S.Ct. 693. It insists that Petitioners’ only possible claims of injury from the alleged “regulatory basis” violation are purported harm to members caused by the final Phase II Rule itself or harm to members caused by EPA’s alleged failure to provide adequate notice of future regulatory requirements in the 1995 Report. However, NRDC contends that Petitioners have not suffered the requisite injury, because they had actual notice that EPA might regulate small construction sites, 63 Fed. Reg. at 1583, and they can show no chain of causation linking their alleged injury from the Rule itself to the actions challenged here.

NRDC’s causation argument is complex. Athough the Petitioners purport to challenge EPA’s failure to follow all of the 1995 Report’s recommendations in the final Phase II Rule, NRDC contends, they are really challenging the subsequent proceedings through which EPA developed the final Rule. Even if there were some unlawful variance between the 1995 report and final rule, NRDC continues, the cause of that variance would have been some failure to abide by rulemaking standards during administrative proceedings that produced the text of the final Rule — not EPA’s attention to sources of input other than the 1995 Report. NRDC maintains that these intervening acts of rulemaking (e.g., Phase II Subcommittee activities and the notice-and-comment process) break the requisite chain of causation between EPA’s alleged failure to adhere to recommendations in the 1995 report and the flaws Petitioners allege in the Phase II Rule, which NRDC claims would have been due to “purportedly unlawful EPA decisions on the merits during the subsequent administrative proceedings.” See Northside Sanitary Landfill v. Thomas, 804 F.2d 371, 381-84 (7th Cir.1986) (finding no standing to challenge EPA statements concerning the fate of a hazardous waste facility when subsequent state administrative acts, not EPA comments, would determine the facility’s actual fate).

We note that NRDC’s standing arguments apply equally to the Municipal Petitioners, who can also assert only the harms resulting to members from the Rule itself or from a lack of notice, and that we are thus not only considering the standing of the Industry Petitioners but also that of the Municipal Petitioners to raise the “regulatory basis” claim. That established, we find standing for both.

NRDC essentially argues that petitioners lack standing because (1) they cannot show that being subject to NPDES permitting is the causal result of the procedural injury they urge, (2) they cannot claim any actual notice injury from the alleged procedural wrong because notice was actually given, and (3) they cannot claim standing based on hypothetical injury that may (or may not) arise from future regulation under the residual authority. We can readily agree with the latter two contentions. As discussed above, the “actual injury” requirement of Article III standing precludes judicial consideration of exactly the kind of hypothetical harm the Industry Petitioners allege may follow from use of Phase II authority for future designations of regional sources. Friends of the Earth, 528 U.S. at 180-81, 120 S.Ct. 693. If future Phase II designations cause identifiable injury to Petitioners, they will then be free to pursue that ripe claim. And because EPA clearly issued notice to all regulated parties that they may be subject to regulation under the proposed rule, 63 Fed. Reg. at 1568 (MS4s) and 1582 (construction), petitioners cannot show injury from lack of actual notice.

However, NRDC’s causation argument is less persuasive. NRDC correctly argues that the petitioners cannot establish a definite chain of causation between the EPA’s alleged failure to limit their regulatory basis to the § 402(p)(5) studies and the fact that they now must obtain permits. But this will almost always be true of petitions challenging an agency’s failure to abide by statutory procedural requirements. Because all administrative deci-sionmaking following an alleged procedural irregularity could always be considered an intervening factor breaking the chain of causation, NRDC’s interpretation of the requisite chain of causation would dubiously shield administrative decisions from procedural review.

For this reason, we have held that the failure of an administrative agency to comply with procedural requirements in itself establishes sufficient injury to confer standing, even though the administrative result might have been the same had proper procedure been followed. City of Davis v. Coleman, 521 F.2d 661, 671 (9th Cir.1975) (agency’s failure to comply with National Environmental Policy Act’s procedural requirements constituted injury sufficient to support standing of a geographically related plaintiff regardless of potentially similar regulatory outcome). In City of Davis, we noted that the standing inquiry represents “a broad test, but because the nature and scope of environmental consequences are often highly uncertain before study we think it an appropriate test.” Id. A plaintiff who shows that a causal relation is “probable” has standing, even if the chain cannot be definitively established. Johnson v. Stuart, 702 F.2d 193, 195-96 (9th Cir.1983) (school students and their parents had standing to challenge a statute that limited the texts that might be selected for teaching, even though it could not be shown whether any specific book had been rejected under this statute or for other reasons).

The Supreme Court has also acknowledged that standing may be established by harm resulting indirectly from the challenged acts, Warth v. Seldin, 422 U.S. 490, 504-05, 95 S.Ct. 2197, 45 L.Ed.2d 343 (1975), and that causation may be established if the plaintiff shows a good probability that, absent the challenged action, the alleged harm would not have occurred, Arlington Heights v. Metro. Hous. Dev. Corp., 429 U.S. 252, 262-64, 97 S.Ct. 555, 50 L.Ed.2d 450 (1977).

Thus, although the petitioners cannot show with certainty that the alleged “regulatory basis” violation caused them to be wrongfully subjected to Phase IT permitting requirements, we hold that they have alleged a procedural injury sufficient to support their standing to bring the claim.

b. Merits. Although we resolve the standing issue in favor of the petitioners, we nevertheless affirm the Rule against their claim that EPA violated procedural constraints implied by the authorizing statute, § 402(p)(6).

Congress intended EPA to use all sources of information in developing a comprehensive program to protect water quality to the maximum extent practicable. The statute unambiguously required EPA to base its regulations both on the § 402(p)(5) studies and on consultation with state and local officials. Congress enacted § 402 with full knowledge that EPA would also be required to take account of public comments during the notice and comment phase of administrative rule-making prescribed by the APA.

is MS4s in Urbanized. Areas

The Municipal Petitioners contend that the designation of small MS4s for Phase II regulation according to Census Bureau defined areas of population density (“urbanized areas”) is arbitrary and capricious. They argue that EPA has not established that the Census Bureau’s designation of urbanized areas is correlated with actual levels of pollution runoff in stormwater, and that EPA adopted the designations simply for administrative convenience. We affirm, because the record reflects a reasoned basis for EPA’s decision. See Marsh, 490 U.S. at 378, 109 S.Ct. 1851.

Conceding that the Preamble cites studies purporting to establish “a high correlation between the degree of development/urbanization and adverse impacts on receiving waters due to stormwater,” 64 Fed. Reg. at 68,751, the Municipal Petitioners nevertheless contend that the record contains no “demonstrably correlated, quantified basis on which EPA may reasonably have concluded that any particular population, or any population density, per se establishes that all urban areas having that same characteristic in gross are necessarily appropriate for inclusion as Phase II sources.” Pointing to Leather Industries of America v. EPA, 40 F.3d 392, 401 (D.C.Cir.1994) (rejecting as arbitrary EPA’s regulation of pollutant levels in the absence of data supporting a relationship between the caps and level of risk), Petitioners argue that EPA simply assumed the relationship Congress contemplated it would establish by the § 402(p)(5) studies.

EPA responds that it extensively documented the relationship between urbanization and harmful water quality impacts from stormwater runoff, pointing to its findings that the degree of surface imper-viousness in an area directly corresponds to the degree of harmful downstream pollution from stormwater runoff, 64 Fed. Reg. at 68,724-27, and that it articulated a rational connection between these record facts and its decision to designate small MS4s serving areas of high population density (“urbanized areas”) to protect water quality.

We treat EPA’s decision with great deference because we are reviewing the agency’s technical analysis and judgments, based on an evaluation of complex scientific data within the agency’s technical expertise. See Baltimore Gas & Elec. Co. v. NRDC, 462 U.S. 87, 103, 103 S.Ct. 2246, 76 L.Ed.2d 437 (1983); see also Chem. Mfrs. Ass’n v. EPA, 919 F.2d 158, 167 (D.C.Cir.1990) (“It is not the role of courts to ‘second-guess the scientific judgments of the EPA....’”). We conclude that the record supports EPA’s choice.

The statute simply called upon EPA to “designate stormwater discharges,” other than those designated in Phase I, “to be regulated to protect water quality.” 33 U.S.C. § 1342(p)(6). EPA did so, based on record evidence showing a compelling and widespread correlation between urban stormwater runoff and deleterious impacts on water quality. Petitioners’ assertion that EPA failed to establish a “quantified” basis for its designation is inapposite. The statute did not require EPA to establish with pinpoint precision a numeric population threshold within urbanized areas that would justify regulation under Phase II. In areas implicating technical expertise and judgment, courts do not require “perfect stud[ies]” or data. Sierra Club, 167 F.3d at 662. EPA satisfied the Leather Industries standard by adopting a threshold consistent with the criterion of “protecting water quality,” and did not assume, but instead sufficiently documented, the relationship between urbanization and harmful stormwater discharge.

3. Small Construction Sites

Industry and Municipal Petitioners also argue that EPA’s decision to regulate under Phase II all construction sites disturbing between one and five acres of land (“small construction sites”) is arbitrary and unsupported by the record. We do not agree. See Marsh, 490 U.S. at 378, 109 S.Ct. 1851.

a. Record Evidence. Municipal Petitioners claim that EPA arrived at the one-acre standard based not on factual findings in the record but instead as a reaction to the earlier Ninth Circuit remand of the Phase I five-acre designation. They allege that the one-acre standard is no more based on supporting data than the rejected five-acre standard, and is thus quantitatively arbitrary.

Industry Petitioners argue that EPA’s findings do not support regulation of all small construction sites, but indicate only that small construction sites, taken cumulatively, may cause effects similar to large sites in a given area. They contend that EPA’s conclusion that adverse effects are possible under certain circumstances cannot support categorical designation of all small construction sites nationwide, and that the Rule is arbitrary because (1) it is based on an analysis that fails to take account of the frequency of negative impacts, (2) it fails to take account of acknowledged factors that determine whether small construction activities cumulatively cause harm (such as the degree of development in a watershed at any given time), and (3) EPA has acknowledged that the actual water quality impact of construction sites of all sizes varies widely from area to area depending on climatological, geological, geographical, and hydrological influences.

Industry Petitioners further contend that the record does not support the designation of small sites, because almost all of the technical papers EPA relied on focused on larger sites or failed to take account of size, and because the lack of an adequate factual basis for nationwide regulation of small sites makes the Phase II Rule arbitrary and capricious. Am. Petroleum Inst. v. EPA, 216 F.3d 50, 58 (D.C.Cir.2000) (invalidating a solid waste rule because EPA “failed to provide a rational explanation for its decision” declining to exclude oilbearing waste waters from the statutory definition of solid waste).

EPA maintains that construction sites regulated under the Phase II Rule degrade water quality across the United States and that the administrative record unambiguously documents that harm. EPA disputes Petitioners’ assertion that it failed to establish the need to regulate small sites nationwide, but also contends that it is not required to base every administrative decision on a precise quantitative analysis. See Sierra Club, 167 F.3d at 662 (“EPA typically has wide latitude in determining the extent of data-gathering necessary to solve a problem.”).

EPA also disputes petitioners’ assertions that data from studies involving larger construction sites are irrelevant to the Phase II Rule. EPA explains that discharges of sediment due to erosion are the result of the interaction of several factors including soils, slope, precipitation, and vegetation:

For construction sites that are one acre or more, none of the environmental factors contributing to sediment discharges is dependent on the size of the site disturbed. A one-acre site can have the same combination of soils, slope, degree of disturbance and precipitation as a 100-acre site, and consequently can lose soil at the same rate ... and discharge sediments in the same concentrations ... as a 100-acre site.

EPA contends that it is thus reasonable to extrapolate data about small sites from studies of larger ones — and that such an extrapolation may even be forgiving, since small sites are currently less likely to have effective erosion and sedimentation control plans.

Indeed, EPA argues that although adverse water quality impacts of small construction sites have been widely recognized, effective local erosion and sedimentation control programs have not been adopted in many areas. Though not all watersheds are currently adversely effected by small construction sites, EPA notes that the Phase II Rule acts “to protect water quality” both remedially and preventively, and argues that it need not quantify the cumulative effects of discharges from these sites or identify all watersheds that are currently harmed before acting to limit pollution from small sites.

We reverse under the arbitrary and capricious standard only if the agency has relied on factors Congress did not intend it to consider, entirely failed to consider an important aspect of the problem, offered an explanation for its decision contrary to the evidence before the agency, or is so implausible that it could not be ascribed to a difference in view or the product of agency expertise. Motor Vehicle Mfrs. Ass’n, 463 U.S. at 43, 103 S.Ct. 2856. Petitioners’ contention that EPA relied on factors Congress did not intend it to consider was rejected in our earlier discussion of the regulatory basis challenge. They submit no evidence that EPA failed to consider an important aspect of the problem. We cannot say that EPA’s designation of small construction sites is implausible (especially given the support of twenty-some-odd studies of sedimentation from construction sites that EPA reviewed in promulgating the challenged regulations, 64 Fed. Reg. 68,728-31). We could remand this aspect of the Rule only if, as the petitioners urge, EPA’s explanation for its decision to regulate small construction sites were contrary to the record evidence, and it is not.

Petitioners’ primary contention is that evidence in the record suggests it is not possible to provide an explicit, quantitative link between small construction sites and an adverse effect on water quality. But even if this were so, EPA’s decision to regulate preventively small construction sites “to protect water quality” is not inconsistent with the record. Petitioners contend that EPA’s rebanee on data from studies of large construction sites is insufficient to support EPA’s designation of small sites, but EPA has adequately supported its contention that experts can reasonably extrapolate projected water quality impacts from large to small sites. We apply the substantial evidence standard when reviewing the factual findings of an agency, Dickinson v. Zurko, 527 U.S. 150, 156-58, 119 S.Ct. 1816, 144 L.Ed.2d 143 (1999), and find it satisfied here.

Moreover, EPA is not required to conduct the “perfect study.” Sierra Club, 167 F.3d at 662. We defer to an agency decision not to invest the resources necessary to conduct the perfect study, and we defer to a decision to use available data unless there is no rational relationship between the means EPA uses to account for any imperfections in its data and the situation to which those means are applied. Id.; Am. Iron & Steel Inst. v. EPA, 115 F.3d 979, 1004 (D.C.Cir.1997). The record indicates a reasoned basis for EPA’s decision that regulating small construction sites was necessary “to protect water quality” as required by § 402(p)(6).

b. Waivers. Industry Petitioners further contend that EPA’s allowance of regulatory waivers.for small construction sites not likely to cause adverse water quality impacts inappropriately supplements the permitting regulations.

Petitioners argue that EPA has the burden of establishing a comprehensive program to control sources as necessary to protect water quality, and that shifting the burden to individual contractors, businesses, and homeowners to prove they do not harm water quality falls short of meeting this statutory obligation. Citing National Mining Association v. Babbitt, 172 F.3d 906, 910 (D.C.Cir.1999), they argue that EPA’s rebuttable regulatory presumption of water quality impact from small construction activity is unreasonable because the agency has established no scientific likelihood that any given small site will affect water quality. EPA defends the waiver approach as fair and efficient, and argues that the Industrial Petitioners are confusing arguments about the limits of presumptions in evidentiary hearings conducted under the APA.

EPA is correct; the Phase II Rule creates no presumption applicable to an evi-dentiary hearing, and a regulation creating exemptions by waiver is reviewed under the familiar arbitrary and capricious standard. The use of waivers to allow permit exemptions for small sites unlikely to cause adverse impacts is reasonable under that standard.

c. Consistency. Industry Petitioners also argue that EPA’s decision to regulate all small construction sites under the Phase II Rule is arbitrary and capricious because EPA applied a different standard in regulating small construction projects than it applied to other potential sources of stormwater runoff subject to Phase II regulation.

Petitioners contend that EPA decided not to designate other potential sources identified in the § 402(p)(5) studies because it determined that there are not “sufficient data ... available at this time on which to make a determination of potential adverse water quality impacts for the category of sources.” 64 Fed. Reg. at 68,780. Petitioners contend this standard should have been applied to small construction sites as well, but EPA opted to regulate these sources despite an alleged lack of coherent data on small site impacts as a general category.

EPA counters, once again, that it did have adequate data to regulate small construction sites. It contends that construc- ' tion sites of all sizes have greater erosion rates than almost any other land use, and thus are not similarly situated to the potential polluters that EPA chose not to regulate at this time. These sources include secondary industrial activities (for example, maintenance of construction equipment or local trucking for an unregulated facility such as a grocery store) and other unregulated commercial activities (for example, car and truck rental facilities). 64 Fed. Reg. at 68,779. EPA reports that it decided not to categorically regulate these potential sources based both on available data about water quality impacts and on the extent to which potentially adverse water quality impacts are mitigated by existing regulations to which these sources are already subject. Id. at 68,780.

We find no error. See Marsh, 490 U.S. at 378, 109 S.Ct. 1851. EPA acted reasonably in designating all small construction sites for Phase II regulation, and Industry Petitioners point to no record evidence that the nature of pollutant contributions from small construction site discharge is sufficiently similar to pollutants from the non-regulated sources to support the analogy they seek to draw. New Orleans Channel 20 v. FCC, 830 F.2d 361, 366 (D.C.Cir.1987) (an agency does not act irrationally when it treats parties differently, unless the parties are similarly situated). Sufficient evidence supports EPA’s conclusion that small construction sites are not similar enough to these “other sources” to support petitioner’s challenge.

G. Continuing (“Residual”) Designation Authority

The Industry Petitioners argue that EPA acted improperly in retaining authority to designate future sources of stormwa-ter pollution for Phase II regulation as needed to protect federal waters. We disagree.

The Phase II Rule preserves authority for EPA and authorized States to designate currently unregulated stormwater dischargers as requiring permits under the Rule if future circumstances indicate that they warrant regulation “to protect water quality” under the terms of § 402(p)(6). 40 C.F.R. § 122.26(a)(9). In the Phase II Preamble, EPA explains this aspect of the Rule:

Under today’s rule, EPA and authorized States continue to exercise the authority to designate remaining unregulated discharges composed entirely of stormwa-ter for regulation on a case-by-case basis.... Individual sources are subject to regulation if EPA or the State, as the case may be, determines that the storm-water discharge from the source contributes to a violation of a water quality standard or is a significant contributor of pollutants to waters of the United States. This standard is based on the text of section CWA 402(p). In today’s rule, EPA believes, as Congress did in drafting section CWA 402(p)(2)(E), that individual instances of stormwater discharge might warrant special regulatory attention, but do not fall neatly into a discrete, predetermined category. Today’s rule preserves the regulatory authority to subsequently address a source (or category of sources) of stormwater discharges of concern on a localized or regional basis.

64 Fed. Reg. 68,781. The text of the Rule requires a discharger to obtain a permit if the NPDES permit authority determines that “stormwater controls are needed for the discharge based on wasteload allocations that are part of ‘total maximum daily loads’ (TMDLs) that address the pollutants) of concern” or that “the discharge, or category of discharges within a geographic area, contributes to a violation of a water quality standard or is a significant contributor of pollutants to waters of the United States.” 40 C.F.R. §§ 122.26(a)(9)(i)(C)-(D).

1. Statutory Authority

The Industry Petitioners contend that this “residual” designation authority, which would allow a NPDES permitting authority to require at any future time a permit from any stormwater discharge not already regulated, is ultra vires. Although they concede that Congress authorized case-by-case designation in § 402(p)(2)(E), they argue that this authority attached only during the permitting moratorium that ended in 1994, prior to the Phase II rulemaking. They object that EPA has impermissibly designated a category of “not yet identified” sources and preserved authority to regulate them on a case-by-case basis indefinitely into the future.

Petitioners contend that § 402(p)(6) cannot rescue the residual authority because it does not authorize case-by-case identification of discharges to be regulated, and that Congress, had it intended otherwise, would have included language in § 402(p)(6) similar to the case-by-case authority explicitly granted in § 402(p)(2)(E). They also contend that continuing authority to designate sources based on waste load allocations that are part of TMDLs exceeds the scope of authority in § 402(p)(2), which nowhere mentions TMDLs. Finally, they argue that the categorical designation authorized by § 402(p)(6) is only permissible when based on the § 402(p)(5) studies and carried out in consultation with state and local authorities, but that the Rule allows future designations based on agency discretion unaccompanied by adequate demonstration that the source itself is a significant threat to water quality.

EPA counters that § 402(p)(6) authorized the designation, made on the basis of statutorily required sources of input and in consultation with the States, of a third class of discharges to be identified on location-specific bases by the NPDES permitting authority. EPA contends that Petitioners mistake the source of its authority for continuing designations as arising only from § 402(p)(2), discounting the full scope of its authority under § 402(p)(6). EPA argues that it permissibly interpreted § 402(p)(6) as allowing the residual designation authority because its language does not expressly preclude it, and because such authority is consistent with (and arguably required by) that section’s mandate to establish a “comprehensive program” to protect water quality from adverse stormwa-ter discharges. EPA maintains that the structure of § 402(p) reflects “Congress’ intent to assure regulation of all problematic stormwater discharges as expeditiously as reasonably possible — not to limit EPA to a one-time-only opportunity to designate discharges for regulation.”

We review EPA’s interpretation of the statute it administers with deference, Royal Foods Co., 252 F.3d at 1106, and affirm this aspect of the Phase II Rule as a legitimate exercise of regulatory authority conferred by § 402(p). The residual designation authority is grounded both on § 402(p)(6), which broadly authorizes a comprehensive program to protect water quality, and on § 402(p)(2)(5), which authorizes case-by-case designation of certain polluters and categories of polluters.

While not a blank check, § 402(p)(6) authorizes a comprehensive program that allows regional designation of polluting discharges that compromise water quality locally, even if they have not been established as compromising water quality nationally at the time Phase II was promulgated. In allowing continuing designation authority, EPA permissibly designated a third category of dischargers subject to Phase II regulation — those established locally as polluting U.S. waters — following all required studies and consultation with state and local officials. EPA reasonably determined that discharges other than those from small MS4s and construction sites were likely to require regulation “to protect water quality” in satisfaction of the § 402(p)(6) mandate. EPA reasonably determined that, although it lacked sufficient data to support nationwide, categorical designation of these sources, particularized data might support their designations on a more localized basis. EPA reasonably interpreted § 402(p)(6) as authorizing regional designation of sources and regional source categories, based on water quality standards including TMDLs.

Petitioners’ § 402(p)(2)(5) argument (that EPA could not draw support for the residual designation authority from § 402(p)(2)(5) because such authority expired in 1994) is contradicted by the plain language of the statute. Respondent-in-tervenor NRDC correctly notes that § 402(p)(l) sets forth a permitting moratorium for stormwater discharges prior to 1994, and that § 402(p)(2) exempts certain categories of sources from that permitting moratorium, including those to be regulated on a case-by-case basis under § 402(p)(2)(5). Specifically, the statute provides that the 1994 date “shall not apply” to the five categories of discharges listed in § 402(p)(2). The termination of a moratorium that “shall not apply” to the continuing designation authority under § 402(p)(2)(5) cannot rescind EPA’s authority to regulate sources in that category. Nothing in § 402(p) suggests that authority to designate these sources ends at any time, and EPA remains free to designate § 402(p)(2)(E) dischargers.

Finally, although Petitioners may be legitimately concerned that a permitting authority may designate a source without adequately establishing its eligibility, this issue must be addressed in the context of an actual case or controversy. Whether a NPDES authority may impose permitting requirements on a discharger without an adequate finding of polluting activity is not yet ripe for judicial review. Thomas v. Anchorage Equal Rights Comm’n, 220 F.3d 1134, 1141 (9th Cir.2000) (“A concrete factual situation is necessary to delineate the boundaries of what conduct the government may or may not regulate.”).

2. Nondelegation Doctrine

Industry Petitioners contend that EPA’s interpretation of § 402(p) to allow the residual designation authority must be rejected because it would render the statute unconstitutional under the nondelegation doctrine. We deny petitioners’ claim, both because it is not properly raised and because it rests on an interpretation explicitly overturned by the United States Supreme Court.

Petitioners base their contention on American Trucking Ass’ns v. EPA, 175 F.3d 1027, 1034 (D.C.Cir.1999), in which the D.C. Circuit remanded a regulation under the nondelegation doctrine because, although EPA had applied reasonable factors in establishing the air quality standards in question, the agency had articulated no “intelligible principle” to channel its application of these factors. Id. Petitioners argue that if § 402(p) authorizes a NPDES permitting authority to require Phase II permitting of any stormwater source deemed to be a “significant contributor” of pollutants to U.S. waters, then that grant of authority likewise constitutes an unconstitutional delegation of legislative authority because — as did the American Trucking delegation — it “leaves [EPA] free to pick any point” at which a regulatory burden will attach. Id. at 1037.

However, in reversing American Trucking, the Supreme Court rejected the notion that an agency has the power to interpret a statute so as to either save it from being, or transform it into, an unconstitutional delegation. Whitman v. Am. Truck ing Ass’ns, 531 U.S. 457, 473, 121 S.Ct. 903, 149 L.Ed.2d 1 (2001). Whether a statute delegates legislative power “is a question for the courts, and an agency’s [interpretation] has no bearing upon the answer.” Id. Petitioner’s argument to the contrary rests on the very reasoning in American Trucking that was overturned in Whitman. The relevant question is not whether EPA’s interpretation is unconstitutional, but whether the statute itself is unconstitutional — a challenge Industry Petitioners do not raise.

But even if the challenge were properly raised, § 402(p) would, like the Clean Air Act standard-setting provision at issue in Whitman, survive constitutional review. The Supreme Court has upheld against nondelegation attacks many similar statutes establishing nonquantitative standards. Am. Power & Light Co. v. SEC, 329 U.S. 90, 104, 67 S.Ct. 133, 91 L.Ed. 103 (1946) (upholding statute giving SEC authority to modify corporate structures so that they are not “unduly or unnecessarily complicate[d]” and do not “unfairly or inequitably distribute voting power among security holders”); Yakus v. United States, 321 U.S. 414, 419-20, 423-27, 64 S.Ct. 660, 88 L.Ed. 834 (1944) (upholding statute giving agency power to set prices that “will be generally fair and equitable”). In Ya-kus, the Court held that a statutory command to “effectuate the purposes” of the overall statutory scheme withstood scrutiny. Id. Section 402(p)(6)’s directive “to protect water quality” summarizes the central purpose of the Clean Water Act, “to restore and maintain the chemical, physical, and biological integrity of the Nation’s waters,” 33 U.S.C. § 1251(a). It establishes a determinate criterion of the kind the Supreme Court upheld in Yakus and American Power & Light.

3. Notice and Comment

Industry Petitioners also contend that, to the extent it allows the designation of entire categories of sources, rather than individual sources, the residual designation authority violates the APA, 5 U.S.C. § 553(b)(3), because EPA did not provide public notice that it was considering such a rule. Ober v. EPA 84 F.3d 304, 315 (9th Cir.1996) (invalidating EPA rule where it deviated from proposal); Shell Oil Co. v. EPA 950 F.2d 741, 746-47 (D.C.Cir.1991). Petitioners contend that while the proposed rule would have allowed case-by-case designation where an authority “determines that the discharge contributes to a violation,” 63 Fed. Reg. at 1635 (proposing 40 C.F.R. § 122.26(a)(9)(i)(D)), the final rule authorizes case-by-case designation where “the discharge, or category of discharges within a geographic area, contributes to a violation,” 40 C.F.R. § 122.26(a)(9)(i)(D).

EPA notes that it had proposed to promulgate continuing designation authority in some form, and points to elements in the proposed rule that explicitly envision the categorical designation of sources at the loeal/watershed level.

According to the “logical outgrowth” standard, a final regulation must be “in character with the original proposal and a logical outgrowth of the notice and comments.” Hodge, 107 F.3d at 712. EPA emphasized that it was considering continuing designations based on watershed data rather than designating these sources on a national basis, and invited comment regarding this proposal. 63 Fed. Reg. at 1536. This supports the necessary relationship between the proposed and final rule.

H. Regulatory Flexibility Act

The Industry Petitioners contend that the Phase II Rule will impose substantial compliance costs on their members and other small entities, but that EPA failed to conduct the analysis required by the Regulatory Flexibility Act (“RFA”), 5 U.S.C. §§ 601-11. They argue that EPA seeks to excuse its noncompliance by falsely certifying that the Rule does not have a significant impact on a substantial number of small entities. 64 Fed. Reg. at 68,800. We are not persuaded.

The RFA requires a federal agency to prepare a regulatory flexibility analysis and an assessment of the economic impact of a proposed rule on small business entities, 5 U.S.C. § 604, unless the agency certifies that the proposed rule will not have a “significant economic impact on a substantial number of small entities” and provides a factual basis for that certification, id. at § 605; N.W. Mining Ass’n v. Babbitt, 5 F.Supp.2d 9, 15-16 (D.D.C.1998).

EPA did certify that the Phase II Rule would not yield “significant impacts,” 64 Fed. Reg. at 68,800, but Petitioners contend this certification is erroneous because (1) EPA treats as “not significant” costs that are in fact significant, and (2) EPA failed to account for the entire universe of small entities affected (including small home construction contractors) and all significant costs to those entities. They urge that the failure to consider a significant segment of the affected small entity community requires invalidation of the Rule, citing North Carolina Fisheries Ass’n v. Daley, 27 F.Supp.2d 650, 659 (E.D.Va.1998) (certification failed to comply with RFA where agency ignored several categories of affected small entities), and Northwest Mining, 5 F.Supp.2d at 15 (RFA was violated where improper definition of small entity excluded analysis of affected entities).

EPA maintains that its certification was appropriate, and, moreover, that it has already voluntarily followed the additional RFA procedures that the Industry Petitioners now request. EPA argues that Petitioners have incorrectly specified the costs that the small entities they represent will bear, referring erroneously to EPA’s total annual compliance costs estimates for all entities, rather than to costs estimated for small entities as defined under the RFA. EPA maintains that it did consider economic impacts on small home construction contractors who might be denied discharge permits, and that it evaluated the annual costs of Phase II compliance associated with any land disturbance between one and five acres. 64 Fed. Reg. at 68,-800-01.

Respondent-intervenor NRDC contends that Petitioners’ reliance on measures of the aggregate impact of the Rule on small entities to determine compliance with the threshold test under the RFA fails as a matter of law because aggregate measures are not consistent with the statutory language setting out that test. NRDC notes that the plain language of § 605(b) sets out a three-component test indicating that EPA need not perform a regulatory flexibility analysis if it finds that the proposed rule will not have: (1) “a significant economic impact” on (2) “a substantial number” of (3) “small entities.” 5 U.S.C. § 605(b). NRDC contends that EPA satisfied the statutory test, and that Petitioners’ interpretation, which rewrites the test to omit the “substantial number” component, is erroneous.

We believe NRDC correctly interprets the statute, Marsh, 490 U.S. at 378, 109 S.Ct. 1851, and that EPA reasonably certified that the Phase II Rule would not have a significant economic impact in compliance with the Regulatory Flexibility Act. We also conclude that, even if EPA had failed to properly comply with the procedural requirements of the RFA, its actual assessment of the Rule’s economic impacts renders any defective compliance harmless error. In granting relief under RFA § 611, a court may order an agency “to take corrective action consistent with” the RFA and APA, including remand to the agency, 5 U.S.C. § 611(a)(4)(A), but EPA has already conducted the economic analyses Petitioners seek when it convened the “Small Business Advocacy Review Panel” before publishing notice of the proposed rule. 64 Fed. Reg. at 68,801. That Panel evaluated the Rule and considered the comments of small entities on a number of issues, consistent with the procedures described in RFA § 603. Id. Appendix 5 of EPA’s preamble to the proposed rule explained provisions that had been designed to minimize impacts on small entities, based on advice and recommendations from the Panel. 63 Fed. Reg. 1615, 64 Fed. Reg. 68,811. Modifications for small entities included alternative compliance and reporting mechanisms responsive to the resources of small entities, simplified procedures, performance rather than design standards, and waivers.

Any hypothetical noncompliance would thus have been harmless, since the available remedy would simply require performance of the economic assessments that EPA actually made. Like the Notice and Comment process required in administrative rulemaking by the APA, the analyses required by RFA are essentially procedural hurdles; after considering the relevant impacts and alternatives, an administrative agency remains free to regulate as it sees fit. We affirm the Rule against this challenge.

III.

CONCLUSION

We conclude that the EPA’s failure to require review of NOIs, which are the functional equivalents of permits under the Phase II General Permit option, and its failure to make NOIs available to the public or subject to public hearings contravene the express requirements of the Clean Water Act. We therefore remand these aspects of the Small MS4 General Permit option so that EPA may take appropriate action to comply with the Clean Water Act. We also remand so that EPA may consider in an appropriate proceeding the Environmental Petitioners’ contention that § 402(p)(6) requires EPA to regulate forest roads. We affirm all other aspects of the Phase II Rule against the statutory, administrative, and constitutional challenges raised in this action.

Petitions for Review GRANTED IN PART and DENIED IN PART.

TALLMAN, Circuit Judge,

concurring in part and dissenting in part:

I concur in most of the majority’s opinion, but I dissent from Section II.B, which remands the Phase II Rule because its system of general permits is “arbitrary and capricious.” I believe EPA’s design of a system of general permits supported by notices of intent was a reasonable exercise of EPA’s administrative discretion. We must give deference to EPA’s interpretation of the laws it is charged with enforcing, so long as EPA’s reading of those laws is permissible. Because EPA acted reasonably in designing a National Pollutant Discharge Elimination System (“NPDES”) based on general permits and supported by NOIs, I respectfully dissent from the court’s decision to remand this portion of the Phase II Rule.

I

As the majority concedes, we evaluate EPA’s interpretation of the Clean Water Act with deference. Majority Op. 13796. If Congress’s intent is unclear as to whether a system of general permits supplemented by NOIs is allowed, we simply ask “whether EPA’s interpretation is permissible.” Ober v. Whitman, 243 F.3d 1190, 1193 (9th Cir.2001).

II

As an initial matter, then, we must ask if Congress was clear in its intent concerning the propriety of a system of general permits augmented by NOIs.

Five legislative commands guide this inquiry. First, 33 U.S.C. § 1342(p)(6) charges EPA with creating a system to regulate stormwater discharges. Plainly, nothing in this section speaks to whether EPA may utilize a general permit approach in regulating stormwater discharge.

Second, 33 U.S.C. § 1311(a) makes it illegal to discharge pollutants “except as in compliance” with several sections of the Clean Water Act. Again, nothing in this section addresses whether EPA may make use of general permits reinforced by NOIs.

Third, 33 U.S.C. § 1342 in general (as opposed to the limited charge in section 1342(p)(6) discussed above) authorizes EPA to issue NPDES permits, provided that the permits satisfy several conditions. But nothing in section 1342 prohibits the use of a system of general permits.

Fourth, the Clean Water Act mandates that “a copy of each permit application and each permit issued under” the NPDES permitting program be made available to the public for inspection and photocopying. 33 U.S.C. § 1342®. The Act does not elaborate on this naked requirement. There is no explanation of the manner in which NPDES permits and applications are to be made publicly available. Nor does the Act define what constitutes a “permit” that would trigger these requirements.

And fifth, the Clean Water Act authorizes the issuance of an NPDES “permit” “after opportunity for public hearing.” 33 U.S.C. § 1342(a)(1). The Act does not provide a definition of “permit,” nor does it further detail what triggers the requirement of a public hearing.

In short, the Clean Water Act fails to address the propriety of a general permit system, or whether NOIs ought to be considered “permits.” Therefore, we should uphold EPA’s creation of a system of general permits buttressed by NOIs so long as it is “permissible.” See Chevron, U.S.A., Inc. v. Natural Resources Defense Council, 467 U.S. 837, 843-44, 104 S.Ct. 2778, 81 L.Ed.2d 694 (1984). Our duty to defer to EPA in such a situation is based on sound policy. Given the overwhelming challenge and complexity of the programs administered by federal agencies today, it is sensible to trust agencies with the design of those programs so long as the programs are reasonable interpretations of congressional mandates.

The central issues regarding EPA’s general permit system are whether the Clean Water Act allows such a system and whether NOIs should be considered “permits.” The resolution of these issues requires a complicated weighing of policies (e.g., administrative streamlining vs. robust inquiry) that is precisely what agencies are designed to do and courts are without the resources or expertise to do. “[I]f the statute is silent or ambiguous with respect to the specific issue, the question for the court is whether the agency’s answer is based on a permissible construction.” Chevron, 467 U.S. at 843, 104 S.Ct. 2778.

Ill

The Phase II Rule promulgates a system of general permits. EPA contemplated that these general permits will be issued on a watershed basis, with individual stormwater dischargers then filing NOIs to operate under general permits. The federal regulations implementing this system repeatedly emphasize that “[t]he use of general permits, instead of individual permits, reduces the administrative burden of permitting authorities, while also limiting the paperwork burden on regulated parties.” 64 Fed. Reg. 68,722, 68,737, 68,-762 (Dec. 8, 1999).

The use of a general permit system for the administration of the NPDES system has been considered and approved before. In NRDC v. Costle, 568 F.2d 1369 (D.C.Cir.1977), the District of Columbia Circuit considered a challenge to EPA’s regulations under the Federal Water Pollution Control Act, which was the precursor to the Clean Water Act. In Costle, EPA sought approval of its design for the NPDES system. EPA had issued regulations exempting broad categories of point sources from the requirement that an NPDES permit be obtained before discharging into federal waters. Part of EPA’s rationale in creating the exempted categories was that otherwise EPA would be overwhelmed by the administrative burden of issuing NPDES permits. Id. at 1377-79. The Costle court affirmed the lower court’s rejection of these exemptions because the legislation in question plainly required that all point sources obtain some kind of NPDES permit. Id. But in rejecting EPA’s regulations, the Costle court discussed the options available to EPA in promulgating an NPDES system that was considerate of the enormous burden such a system could impose on EPA. Id. at 1380-81. In particular, the court recommended “the use of area or general permits. The Act allows such techniques. Area-wide regulation is one well-established means of coping with administrative exigency.” Id. at 1381 (emphasis added).

Against this backdrop, EPA’s creation of a general permit system was entirely permissible. And if the creation of a general permit system is permissible, then it does not matter whether NOIs are given a public airing.

The majority contends that the general permit system prevents EPA from fulfilling its duty to make sure that municipalities do not discharge pollutants in violation of the Clean Water Act. The majority reasons that by failing to require EPA review of NOIs, the Rule fails to ensure that a regulated MS4’s stormwater pollution control program will satisfy the Clean Water Act requirement that the MS4 “reduce discharges to the maximum extent practicable.” Majority Op. 855. But the majority’s analysis ignores the effects of the general permit. By filing an NOI, a discharger obligates itself to comply with the limitations and controls imposed by the general permit under which it intends to operate. EPA mandates that all permits (including general permits) condition their issuance on satisfaction of pollution limitations imposed by the Clean Water Act. 40 C.F.R. § 122.44. In particular, EPA requires permits to satisfy the restrictions imposed by Clean Water Act section 307(a). Id. at § 122.44(b)(1). Therefore, the general permit imposes the obligations with which the discharger must comply (including applicable Clean Water Act standards), and EPA’s decision not to review every NOI is not a failure to insure compliance with the Clean Water Act.

The majority also objects to EPA’s general permit system because it fails to allow for sufficient public participation in the NOIs. Majority Op. 856-858. The majority’s position fails to give deference to EPA and imposes the majority’s own wishes instead. EPA would have been justified in creating a system entirely reliant on general or area permits. Its imposition of NOIs is an indulgence to certain policy prerogatives, namely public involvement and the collection of additional information. But the power to create a general permit system necessarily implies the power to require subordinate steps for NOIs that do not quite reach the level of inquiry associated with actual permits.

IV

We function as an adjudicator of disputes, not as a policy-making body. Where an agency promulgates rules after a deliberative process, it is incumbent upon us to respect the agency’s decisions or else risk trivializing the function of that agency. In this case, EPA made a permissible decision to create a general permit program supported by NOIs. Therefore, I respectfully dissent from Section II.B of the majority’s opinion. 
      
      . The “Phase II Rule” reviewed here is the product of the second stage of EPA’s two-phase stormwater rulemaking effort. The "Phase I Rule,” governing larger-scale storm-water discharges, was issued in 1990 and reviewed by this court in Natural Res. Def. Council v. EPA, 966 F.2d 1292 (9th Cir.1992).
     
      
      . Richard G. Cohn-Lee and Diane M. Cameron, Urban Stormwater Runoff Contamination of the Chesapeake Bay: Sources and Mitigation, The Environmental Professional, Vol. 14, p. 10, at 10 (1992); see also Natural Res. Def. Council, 966 F.2d at 1295 (citing a study by the Nationwide Urban Runoff Program).
     
      
      . Regulation for Revision of the Water Pollution Control Program Addressing Storm Water, 64 Fed. Reg. 68,722, 68,724, 68,727 (Dec. 8, 1999) (codified at 40 C.F.R. pts. 9, 122, 123, and 124).
     
      
      . Id. at 68,726.
     
      
      . Id.
      
     
      
      
        . Id. at 68,725-31.
     
      
      . A point source is “any discernible, confined and discrete conveyance, including but not limited to any pipe, ditch, channel, tunnel, conduit, well, discrete fissure, container, rolling stock, concentrated animal feeding operation, or vessel or other floating craft, from which pollutants are or may be discharged.” 33 U.S.C. § 1362(14).
     
      
      .Diffuse runoff, such as rainwater that is not channeled through a point source, is considered nonpoint source pollution and is not subject to federal regulation. Oregon Natural Desert Ass’n v. Dombeck, 172 F.3d 1092, 1095 (9th Cir.1998).
     
      
      . National Pollutant Discharge Elimination System Permit Application Regulations for Stormwater Discharges, 55 Fed. Reg. 47,990 (Nov. 16, 1990) (codified at 40 C.F.R. pt. 122-124). The Phase I rule was challenged in this court in Natural Res. Def. Council, 966 F.2d at 1292. We held, inter alia, that EPA must impose deadlines for permit approvals, id. at 1300, that EPA's decision to regulate construction sites only over five acres in size was arbitrary and capricious, id. at 1306, and that EPA did not act capriciously in defining "municipal,” id. at 1304, or in placing differently-sized municipalities on different permitting schedules, id. at 1301.
     
      
      . Proposed Regulations for Revision of the Water Pollution Control Program Addressing Storm Water Discharges, 63 Fed. Reg. 1536 (proposed Jan. 9, 1998).
     
      
      . Pub. L. No. 106-74, § 431(a), 113 Stat. 1047, 1096 (1999) ("Appropriations, 2000— Department of Veterans Affairs and Housing and Urban Development, and Independent Agencies”).
     
      
      . Regulations for Revision of the Water Pollution Control Program Addressing Storm Water Discharges, 64 Fed. Reg. 68,722 (Dec. 8, 1999) (codified at 40 C.F.R. pts. 9, 122, 123, and 124).
     
      
      . The Rule also allows a small MS4 to be regulated under an individual NPDES permit covering a nearby large or medium MS4, with provisions adapted to address the small MS4. 40 C.F.R. § 122.33(b)(3).
     
      
      .The text o£ that section reads: "Not later than October 1, 1993, [EPA], in consultation with state and local officials, shall issue regulations (based on the results of the studies conducted under paragraph (5)) which designate stormwater discharges, other than those discharges described in paragraph (2), to be regulated to protect water quality and shall establish a comprehensive program to regulate such designated sources. The program shall, at a minimum, (A) establish priorities, (B) establish requirements for State stormwa-ter management programs, and (C) establish expeditious deadlines. The program may include performance standards, guidelines, guidance, and management practices and treatment requirements, as appropriate.” 33 U.S.C. § 1342(p)(6).
     
      
      . The lesser category of "permits” may also be implied by the inclusion of "performance standards” in the list of possible program features.
     
      
      . "Where Congress includes particular language in one section of a statute but omits it in another section of the same Act, it is generally presumed that Congress acts intentionally and purposely in the disparate inclusion or exclusion.” Bates v. United States, 522 U.S. 23, 29-30, 118 S.Ct. 285, 139 L.Ed.2d 215 (1997).
     
      
      . The Phase II Rule also allows a small MS4 to be regulated under an NPDES permit covering a nearby large or medium-sized MS4, with provisions adapted to address the small MS4. 40 C.F.R. § 122.33(b)(3). ther to obtain NPDES permits or to stop discharging stormwater.
     
      
      . The Municipal Petitioners argue that the Minimum Measures exceed EPA’s statutory authority under § 402(p) of the Clean Water Act. We disagree. The list of elements for a regulatory program that appears in § 402(p)(6) is nonexclusive, and EPA's adoption of the Minimum Measures represents a permissible interpretation of its authority under § 402(p)(6). See Chevron, 467 U.S. at 843-44, 104 S.Ct. 2778.
      The Municipal Petitioners argue that EPA is not entitled to Chevron deference, and that the Minimum Measures must be rejected absent a clear statement of congressional intent that EPA enact the Minimum Measures. The Municipal Petitioners argue that this clear statement requirement arises because there are "significant constitutional questions” about the permissibility of the Minimum Measures under the Tenth Amendment, and because the Minimum Measures alter "the federal-state framework by permitting federal encroachment upon a traditional state power.” Solid Waste Agency of N. Cook County v. Army Corps of Eng'rs, 531 U.S. 159, 173, 121 S.Ct. 675, 148 L.Ed.2d 576 (2001).
      As we explain, because the Phase II Rule includes at least one alternative to the Minimum Measures, i.e., the option of seeking a permit under 40 C.F.R. § 122.26(d), the Minimum Measures do not present significant Tenth Amendment problems demanding a clear statement of congressional intent. Nor does the Phase II Rule altér the federal-state balance. To the contrary, the option of seeking a permit under 40 C.F.R. § 122.26(d) maintains precisely the same federal-state balance as existed prior to the Phase II Rule. See, e.g., Natural Res. Def. Council v. EPA, 966 F.2d 1292 (9th Cir.1992) (reviewing Phase I Rule); Natural Res. Def. Council v. Costle, 568 F.2d 1369, 1379 (D.C.Cir.1977) (denying EPA authority to exempt MS4s from regulation under the Clean Water Act). Furthermore, even if a clear statement of congressional intent were necessary, § 402(p) of the Clean Water Act is replete with clear statements that Congress intended EPA to require MS4s ei-
     
      
      . This subsection provides that permit seekers must, ”[t]o the extent allowable under State, Tribal, or local law, effectively prohibit, through ordinance or other regulatory mechanism, non-stormwater discharges into your storm sewer systems and implement appropriate enforcement procedures and actions. ...” 40 C.F.R. § 122.34(b)(3)(ii)(B).
     
      
      . This subsection provides that permit seekers "must develop, implement, and enforce a program to reduce pollutants in any storm water runoff to your small MS4 from construction activities that result in a land disturbance of greater than or equal to one acre.... [The] program must include the development and implementation of, at a minimum: (A) An ordinance or other regulatory mechanism to require erosion and sediment controls, as well as sanctions to ensure compliance, to the extent allowable under State, Tribal, or local law; (B) Requirements for construction site operators to implement appropriate erosion and sediment control best management practices; (C) Requirements for construction site operators to control waste such as discarded building materials, concrete truck washout, chemicals, litter, and sanitary waste at the construction site that may cause adverse impacts to water quality; (D) Procedures for site plan review which incorporate consideration of potential water quality impacts; (E) Procedures for receipt and consideration of information submitted by the public, and (F) Procedures for site inspection and enforcement control measures.” 40 C.F.R. §§ 122.34(b)(4)(i)-(ii).
     
      
      .This subsection provides that permit seekers must "[u]se an ordinance or other regulatory mechanism to address post-construction runoff from new development and redevelopment projects [disturbing one acre or more] to the extent allowable under State, Tribal or local law.” 40 C.F.R. §§ 122.34(b)(5)(ii)(B).
     
      
      . EPA and NRDC also argue that the Minimum Measures are facially constitutional, and that the Phase II Rule presents no Tenth Amendment difficulties because operators of small MS4s may avoid stormwater regulation entirely by electing not to discharge stormwa-ter into federal waters in the first place. In light of our holding with regard to the Alternative Permit option, we do not consider these arguments.
     
      
      .We decline to address two further arguments raised by EPA: first, that municipalities do not receive full First Amendment protections, under Muir v. Alabama Educational Television Commission, 688 F.2d 1033, 1038 n. 12 (5th Cir.1982) (en banc) ("Government expression, being unprotected by the First Amendment, may be subject to legislative limitation which would be impermissible if sought to be applied to private expression and Aldrich v. Knab, 858 F.Supp. 1480, 1491 (W.D.Wash.1994) (holding that “unlike private broadcasters, the state itself does not enjoy First Amendment rights”), and second, that even if the First Amendment were fully applicable, the Phase II regulations would satisfy them because MS4s may avoid the compulsion to speak by seeking a permit under the Alternative option, 40 C.F.R. § 122.26(d)(2)(iv), rather than under the Minimum Measures.
     
      
      . As a subsidiary matter, we note that it also falls short of compelling the MS4 to "regulate” third parties in contravention of the Tenth Amendment. Dispensing information to facilitate public awareness about safe disposal of toxic materials constitutes “encouragement,” not regulation.
     
      
      . "When the constitutional validity of a statute or regulation is called into question, it is a cardinal rule that courts must first determine whether a construction is possible by which the constitutional problem may be avoided.” Meinhold, 34 F.3d at 1476.
     
      
      . In its most recent treatment of compelled speech, the Supreme Court held that a generic advertising campaign violated free speech where the message was specific and antagonistic to the preferred advertising message of the plaintiff, and the regulation compelling participation was not part of a broader regulatory apparatus already constraining the plaintiff's autonomy in the relevant arena. United States Dep’t. of Agriculture v. United Foods, 533 U.S. 405, 410-17, 121 S.Ct. 2334, 150 L.Ed.2d 438 (2001). The court distinguished this advertising program from the one in Glickman on the latter point: "[t]he program sustained in Glickman differs from the one under review in a most fundamental respect. In Glickman the mandated assessments for speech were ancillary to a more comprehensive program restricting market autonomy.” Id. at 411, 121 S.Ct. 2334. Although the Phase II Rule is not an advertising or marketing regulation, it constitutes a "comprehensive program” restricting the autonomy of MS4s in the relevant arena of controlling toxic discharges to storm sewers that drain to U.S. waters.
     
      
      . In deciding the similar question of whether a regulation impermissibly compelled speech by requiring manufacturers of mercuiy-con-taining products to inform consumers how to dispose safely of the toxic material, the Second Circuit held that "mandated disclosure of accurate, factual, commercial information does not offend the core First Amendment values of promoting efficient exchange of information or protecting individual liberty interests.” Nat’l Elec. Mfrs. Ass'n v. Sorrell, 272 F.3d 104, 114 (2d Cir.2001). What speech may follow from the Phase II directive will not be "commercial” in the same sense that manufacturer labeling is, but it will be similar in substance to Sorrell to the extent that it informs the public how to dispose safely of toxins. We think the policy considerations underlying the commercial speech treatment of labeling requirements, see, e.g., the Federal Cigarette Labeling and Advertising Act, 15 U.S.C. §§ 1333-39, apply similarly in the context of the market-participant municipal storm sewer provider.
     
      
      . The Alternative option contains a public education requirement that is similar but even less specific, and therefore even less burdensome, than the requirements in the Minimum Measures. See § 122.26(d)(2)(iv)(B)(6) (requiring permit seekers to propose programs to counter illicit discharges, including a "description of educational activities, public information activities, and other appropriate activities to facilitate the proper management and disposal of used oil and toxic materials”).
     
      
      . Municipal Petitioners concede that "simplified individual permit application requirements” were discussed, but they contend that the permit requirements discussed are not sufficiently similar to those promulgated to establish a logical outgrowth.
     
      
      . EPA argues that the Environmental Petitioner's challenge is not ripe for review because "the question of whether some general permit somewhere might fail to assure that pollutants are reduced to the maximum extent practicable is not ripe for review.” But we are not addressing the merits of any specific permit. Rather, the question before us "is purely one of statutory interpretation that would not benefit from further factual development of the issues presented.” Whitman v. American Trucking, 531 U.S. 457, 479, 121 S.Ct. 903, 149 L.Ed.2d 1 (2001). Specifically, we are addressing whether EPA, in promulgating the Phase II Rule, has accomplished the substantive controls for municipal storm-water that Congress mandated in § 402(p) of the Clean Water Act. As we held in Natural Resources Defense Council v. EPA, 966 F.2d at 1296-97, 1308, this question is ripe for review.
     
      
      . Petitioners suggest that EPA should be held to the standard it espoused to procure judicial approval for the Phase I program. In .1991, responding to NRDC’s assertion that the Phase I Rule failed to set "hard criteria" for review of MS4 stormwater programs, EPA responded that "inadequate proposals will result in the denial of permit applications." Respondent’s Brief at 67, Natural Res. Def. Council v. EPA, 966 F.2d 1292 (9th Cir.1992) (Nos. 91-70200, 91-70176, & 90-70671). Petitioners contend that this court relied on that representation in ruling for EPA on that issue. Natural Res. Def. Council v. EPA, 966 F.2d at 1308 n. 17 ("Individual NPDES permit writers ... will decide whether application proposals are adequate....").
     
      
      . That the Rule allows a permitting authority to review an NOI is not enough; every permit must comply with the standards articulated by the Clean Water Act, and unless every NOI issued under a general permit is reviewed, there is no way to ensure that such compliance has been achieved.
      The regulations do require NPDES permitting authorities to provide operators of small MS4s with "menus” of management practices to assist in implementing their Minimum Measures, see 40 C.F.R. § 123.35(g), but again, nothing requires that the combination of items that the operator of a small MS4 selects from this “menu” will have the combined effect of reducing discharges to the maximum extent practicable.
      Nor is the availability of citizen enforcement actions a substitute for EPA's enforcement responsibility, especially because, as discussed below, the Rule does not require that NOIs be publicly available. Absent review on the front end of permitting, the general permitting regulatory program loses meaning even as a procedural exercise.
     
      
      . EPA identifies no other general permitting program that leaves the choice of substantive pollution control requirements to the regulated entity, and we are not persuaded by the analogy it urges to the traditional model of general permitting (where NOIs routinely are not reviewed), because, as we have noted, the Phase II general permit model is substantially dissimilar.
     
      
      . In its petition for rehearing, EPA argues for the first time that because the regulations require NPDES Permitting Authorities to include in general permits "any additional measures necessary” to ensure that the maximum extent practicable standard is met, 40 C.F.R. §§ 123.35(h)(1), 123.35(f) (incorporating by reference the "maximum extent practicable” requirement of 40 C.F.R. §§ 122.34(a)), 122.34(f) (requiring small MS4s to comply with additional measures), the Phase II Rule ensures that discharges will be reduced to the maximum extent practicable.
      The trouble with EPA's reasoning is that the Phase II Rule defines the "maximum extent practicable” standard in such a way that no "additional measures” will ever be necessary under § 123.35(h)(1). While a Permitting Authority may impose additional measures, nothing compels it to do so because, merely by implementing the best management practices that the operator of a small MS4 has chosen for itself, that small MS4 will already have met the "maximum extent practicable” standard. See 40 C.F.R. § 122.34(a).
     
      
      . EPA argues for the first time in its petition for rehearing that NOIs will be publicly available under 40 C.F.R. § 122.34(g)(2). Addressing operators of regulated small MS4s, this section provides: "You must make your records, including a description of your storm water management program, available to the public at reasonable times during regular business hours.” While this section does seem to provide for the public availability of a small MS4’s records, we are troubled that nothing in EPA’s initial briefs indicated that EPA considered NOIs to be subject to this section. We normally defer to an agency's interpretations of its own regulations, but we may decline to defer to the post hoc rationalizations of appellate counsel. See, e.g., Martin v. Occupational Safety and Health Review 
        
        Commission, 499 U.S. 144, 150, 156, 111 S.Ct. 1171, 113 L.Ed.2d 117 (1991). If EPA intends this section to provide for the public availability of NOIs — for example because it intends NOIs to be among the records subject to this section — it may clarify on remand.
     
      
      . Agency determinations based on the record are reviewed under the "arbitrary and capricious” standard. 5 U.S.C. § 706(2)(A). The standard is narrow and the reviewing court may not substitute its judgment for that of the agency. Marsh, 490 U.S. at 378, 109 S.Ct. 1851. However, the agency must articulate a rational connection between the facts found and the conclusions made. Washington v. Daley, 173 F.3d 1158, 1169 (9th Cir.1999). The reviewing court must determine whether the decision was based on a consideration of the relevant factors and whether there has been a clear error of judgment. Marsh, 490 U.S. at 378, 109 S.Ct. 1851. The court may reverse under the "arbitrary and capricious" standard only if the agency:
      has relied on factors which Congress has not intended it to consider, entirely failed to consider an important aspect of the problem, offered an explanation for its decision that runs counter to the evidence before the agency, or is so implausible that it could not be ascribed to a difference in view or the product of agency expertise.
      
        Motor Vehicle Mfrs. Ass’n, 463 U.S. at 43, 103 S.Ct. 2856.
     
      
      . EPA explains that the Group A facilities were not regulated with the other Phase I sources because EPA used Standard Industrial Classification Index (SIC) codes in defining the universe of regulated industrial activities: "By relying on SIC codes, a classification system created to identify industries rather than environmental impacts from these industries [sic] discharges, some types of storm water discharges that might otherwise be considered ‘industrial’ were not included in the existing NPDES storm water program." 64 Fed. Reg. at 68,779.
     
      
      . As discussed in footnote 37, Group A facilities were not regulated with other Phase I industrial sources based on a government coding system used to distinguish different types of industry (without reference to their similar environmental impacts). See 64 Fed. Reg. at 68,779.
     
      
      . "In identifying potential categories of sources for designation in today’s notice, EPA considered designation of discharges from Group A and Group B facilities. EPA applied three criteria to each potential category in both groups to determine the need for designation: (1) The likelihood for exposure of pollutant sources included in that cat-egoty, (2) whether such sources were adequately addressed by other environmental programs, and (3) whether sufficient data were available at this time on which to make a determination of potential adverse water quality impacts for the category of sources. As discussed previously, EPA searched for applicable nationwide data on the water quality impacts of such categories of facilities. ...”
      "EPA’s application of the first criterion showed that a number of Group A and B sources have a high likelihood of exposure of pollutants.... Application of the second criterion showed that some categories were likely to be adequately addressed by other programs.”
      "After application of the third criterion, availability of nationwide data on the various storm water discharge categories, EPA concluded that available data would not support any such nationwide designations. While such data could exist on a regional or local basis, EPA believes that permitting authorities should have flexibility to regulate only those categories of sources contributing to localized water quality impairments.... If sufficient regional or nationwide data become available in the future, the permitting authority could at that time designate a category of sources or individual sources on a case-by-case basis.” 64 Fed. Reg. at 68,780.
     
      
      . Guidance Specifying Management Measures For Sources of Nonpoint Pollution in Coastal Waters, EPA guidance paper 840-B-93-001c (Jan. 1993), available at http:// www.epa.gov/owow/nps/mmgi/index.html (last visited Sept. 18, 2002) (“Coastal Waters’’).
     
      
      . The provision provides in full as follows:
      Silvicultural point source means any discernible, confined and discrete conveyance related to rock crushing, gravel washing, log sorting, or log storage facilities which are operated in connection with silvicultural activities and from which pollutants are discharged into waters of the United States. The term does not include non-point source silvicultural activities such as nursery operations, site preparation, reforestation and subsequent cultural treatment, thinning, prescribed burning, pest and fire control, harvesting operations, surface drainage, or road construction and maintenance from which there is natural runoff. However, some of these activities (such as stream crossing for roads) may involve point source discharges of dredged or fill material which may require a CWA section 404 permit (See 33 CFR 209.120 and part 233).
      40 C.F.R. § 122.27(b)(1).
     
      
      . Nonpoint Source Pollution: The Nation’s Largest Water Quality Problem, EPA841-F-96-004A ("Pointer # 1”) ("The latest National Water Quality Inventory indicates that agriculture is the leading contributor to water quality impairments, degrading 60 percent of the impaired river miles and half of the impaired lake acreage surveyed by states, territories, and tribes.”).
     
      
      . The Municipal Petitioners join in asserting the “regulatory basis” claim at Part 11(F)(1).
     
      
      . NRDC argues that this claim is not only meritless for the reasons stated by EPA, but also frivolous, since industry petitioner National Association of Home Builders, as a member of the FACA Phase II Subcommittee, participated in and affirmed that such consultation took place.
     
      
      . See Natural Res. Def. Council, 966 F.2d at 1306 (remanding EPA's decision to regulate only construction sites disturbing more than five acres, after EPA had initially proposed to regulate all sites disturbing more than one acre).
     
      
      . The Industry Petitioners contend that EPA lacked authority to issue the Phase II regulation of construction sites based on a process EPA itself characterized as "separate and distinct” from the development of the Report to Congress. 64 Fed. Reg. at 68,732. They add that the Phase II Rule was not "based on” the 1999 Report ultimately requested by Congress in the Appropriations Act, since EPA’s report in response was released on the very day that the final Phase II Rule was published.
     
      
      . Since we have already determined that AF & PA lacks standing to raise any of its claims, see Section D above, this discussion pertains to the remaining Industry Petitioner, National Association of Home Builders.
     
      
      . Although the issue of Municipal Petitioners’ standing has not been raised by the parties, we are obliged to consider it to determine whether the case-or-controversy requirement of Article III is satisfied. See, e.g., Boeing Co. v. Van Gemert, 444 U.S. 472, 488 n. 4, 100 S.Ct. 745, 62 L.Ed.2d 676 (1980); Juidice v. Vail, 430 U.S. 327, 331, 97 S.Ct. 1211, 51 L.Ed.2d 376 (1977).
     
      
      . Even if the statute were ambiguous, we would defer to EPA's reasonable interpretátion. Chevron, 467 U.S. at 843-44, 104 S.Ct. 2778.
     
      
      . The Industrial Petitioners argue that although the Phase I authorizing statute required EPA to regulate all sources associated with "industrial activity,” Congress expressly directed that the Phase II regulatory program be focused on sources that require regulation "to protect water quality.” They assert that because EPA's rule ignores the variability of water quality impacts nationwide, the Rule is not appropriately targeted on the protection of water quality.
     
      
      . Petitioners heavily critique two studies relied on by EPA that dealt specifically with the water quality impacts of small construction sites, noting that one concludes it is impossible to generalize about the impacts of small sites, Lee H. MacDonald, Technical Justification for Regulating Construction Sites 1-5 Acres in Size, July 22, 1997, and that the other merely concludes that small sites “can have” significant effects if erosion controls are not implemented, David W. Owens, et al., Soil Erosion from Small Construction Sites. Petitioners contend that the latter study was managed with no erosion controls, intentionally producing worst-case sediment runoff and unreasonable estimates of actual sediment yields for small sites nationwide. EPA vigorously defends the studies.
     
      
      .NRDC adds that notwithstanding the clear interest of the National Association of Home Builders ("NAHB,” one of the Industry Petitioners), NAHB's multi-year participation in the FACA Phase II Subcommittee Small Construction and No-Exposure Sites Work Group, and NAHB's own submission of detailed comments on the proposed Rule, NAHB failed to enter into the administrative record any study contradicting the proposition that small construction sites cause water quality problems. NRDC points to the record’s showing that NAHB had itself proposed that regulation of construction sites of two acres or greater was appropriate, and contends that this is thus not a dispute over whether small construction sites should be regulated on a nationwide basis, but instead a technical disagreement over whether EPA should establish a one-acre threshold or a different threshold on a similar small scale.
     
      
      . Whitney Brown and Deborah Caraco, Controlling Stormwater Runoff Discharges from Small Construction Sites: A National Review, Task 5 Final Report submitted by the Center for Watershed Protection to the EPA Office of Wastewater Management, March 1997, IP E.R. 633, 643.
     
      
      . EPA adds that operators of small sites in areas unlikely to suffer adverse impacts may apply for a permit waiver if little or no rainfall is expected during the period of construction (the "rainfall erosivity waiver”) or if regulation is unnecessaiy based on a location-specific evaluation of water quality (the "water quality waiver”). 64 Fed. Reg. at 68,776.
     
      
      .EPA also implies permission to regulate for potential cumulative impacts of small sites from the past directive of this court. When the Phase I industrial discharge regulations were challenged, we found no record data to support that rule’s exemption of construction activities on less than five acres and held that small sites did not categorically qualify for a de minimis exemption because "even small construction sites can have a significant impact on local water quality.” Natural Res. Def. Council, 966 F.2d at 1306.
     
      
      . The “substantial evidence” standard requires a showing of such relevant evidence as a reasonable mind might accept as adequate to support a conclusion. Edlund v. Massanari, 253 F.3d 1152, 1156 (9th Cir.2001).
     
      
      . EPA further argues that even if the waiver provision were properly characterized as an evidentiary presumption, it should be sustained because the record demonstrates that the presumed fact of the water quality impact of small sites is more likely true than not.
     
      
      . EPA notes that the Phase II Rule empowers regional permitting authorities to regulate local sources of these types known to be responsible for harmful water quality impacts via the continuing “residual designation" authority (an aspect of the Rule that Petitioners also challenge).
     
      
      . TMDLs are pollutant loading limits established by NPDES permitting authorities under the Clean Water Act for waters that do not meet a water quality standard due to the presence of a pollutant. See 33 U.S.C. § 1313(d).
     
      
      . This section enables a NPDES permitting authority to designate for regulation: "[a] discharge for which the Administrator or the State, as the case may be, determines that the stormwater discharge contributes to a violation of a water quality standard or is a significant contributor of pollutants to waters of the United States.” 33 U.S.C. § 1342(p)(2)(E).
     
      
      . Notably, Industry Petitioner NAHB itself took the position during Phase II Subcommittee proceedings that the power to designate additional sources survived the promulgation of the Phase II Rule. In a 1996 comment letter to EPA, NAHB asserted its understanding that "[t]he permitting authority still reserves the right to designate additional sources if they are shown to be a contributor of water quality impairment.” NRDC Supplemental Excerpts of Record at 58.
     
      
      . The full text of § 402(p)(6), which specifically authorizes the Phase II program, reads: "Not later than October 1, 1993, the Administrator, in consultation with State and local officials, shall issue regulations (based on the results of the. studies conducted under paragraph (5)) which designate stormwater discharges, other than those discharges described in paragraph (2), to be regulated to protect water quality and shall establish a comprehensive program to regulate such designated sources. The program shall, at a minimum, (A) establish priorities, (B) establish requirements for State stormwater management programs, and (C) establish expeditious deadlines. The program may include performance standards, guidelines, guidance, and management practices and treatment requirements, as appropriate.” 33 U.S.C. § 1342(p)(6).
     
      
      . Petitioners further argue that even if EPA could preserve the case-by-case authority conferred in § 402(p)(2)(E), that section confers authority only to regulate "a discharge” determined to threaten water quality, not a category of discharges. However, we agree with respondent-intervenor NRDC’s argument that § 402(p)(2)(E) does not preclude EPA from designating entire categories of sources. Petitioners' argument follows from its reliance on the fact that § 402(p)(2)(E) refers to "discharge” in the singular rather than the plural to conclude that EPA may only designate sources meeting the § 402(p)(2)(E) description on a case-by-case basis. But all five of the § 402(p)(2)(5) categories refer to "discharge” in the singular, even in reference to discharges clearly intended for categorical regulation, like "a discharge from a municipal separate storm sewer system serving a population of 250,000 or more.” 33 U.S.C. § 1342(p)(2)(C). The error in petitioners' interpretation is exposed by 1 U.S.C. § 1, which provides that "[i]n determining the meaning of any Act of Congress, unless the context indicates otherwise — words importing the singular include and apply to several persons, parties, or things.”
     
      
      . This case was reversed in relevant part by the Supreme Court in Whitman v. Am. Trucking Ass’ns, 531 U.S. 457, 476, 121 S.Ct. 903, 149 L.Ed.2d 1 (2001).
     
      
      . "[T]oday's proposal would encourage [voluntary] control of stormwater discharges ... unless the discharge (or category of discharges) is individually or locally designated as described in the following section. The necessary data to support designation could be available on a local, regional, or watershed basis and would allow the NPDES permitting authority to designate a category of sources or individual sources on a case-by-case basis. If sufficient nationwide data [becomes] available in the future, EPA could at that time designate additional categories of industrial or commercial sources on a national basis. EPA requests comment on the three-pronged analysis used to assess the need to designate additional industrial or commercial sources and invites suggestions regarding watershed-based designation.” 63 Fed. Reg. at 1588.
     
      
      . Our consideration of the issue at all may be gratuitous, since petitioners failed to submit timely comment disputing the adequacy of EPA's consideration of economic impacts on small businesses proposed at 63 Fed. Reg. at 1605-07. United States v. L.A. Tucker Truck Lines, 344 U.S. 33, 37, 73 S.Ct. 67, 97 L.Ed. 54 (1952) ("[C]ourts should not topple over administrative decisions unless the administrative body not only has erred but has erred against objection made at the time appropriate under its practice.”).
     