Full opinion text
SUHRHEINRICH, J., delivered the opinion of the court, in which BOGGS, C. J., BATCHELDER, GILMAN, GIBBONS, ROGERS, SUTTON, and COOK, JJ., joined. MARTIN, J. (pp. 906 - 923), delivered a separate dissenting opinion in which DAUGHTREY, MOORE, COLE, and CLAY, JJ., joined. OPINION SUHRHEINRICH, Circuit Judge. Petitioners Kentucky Resources Council, Inc. (“KRC”) and Citizens Coal Council (“CCC”) (collectively “Petitioners”) challenge a final rule of the Administrator of the United States Environmental Protection Agency (“Administrator” or “EPA”) promulgated under the Federal Water Pollution Control Act, commonly known as the Clean Water Act (“CWA” or the “Act”), 33 U.S.C. §§ 1251-1387. The rule, found at 67 Fed.Reg. 3370 (Jan. 23, 2002), amends the existing effluent limitations guidelines for the Coal Mining Point Source Category at 40 C.F.R. Part 434 by adding two new subcategories: the Coal Remining Subcategory and the Western Alkaline Coal Mine Subcategory (collectively the “Final Rule”). Petitioners argue that the Coal Remining regulations conflict with the specific language adopted by Congress in the Rahall Amendment, 33 U.S.C. § 1311(p), governing pollution abatement at mining sites abandoned before 1977 that companies want to reopen for mining. Petitioners also argue that the creation of the Western Alkaline Mining Subcategory violates the CWA by eliminating numeric pollution limits and that the EPA Administrator acted arbitrarily and capriciously in preferring best management practices to numeric effluent limits for sediment reduction. A panel of this Court invalidated the EPA’s final rule establishing effluent limitations under the CWA for the two subcategories. The panel unanimously rejected Petitioners’ arguments that the Rahall Amendment deprived the EPA of the authority to promulgate the Coal Remining regulations. A majority nonetheless held that the Coal Remining regulations were invalid on grounds not raised by Petitioners or addressed by the EPA; namely, that the EPA failed to follow procedures the majority deemed required by law under 33 U.S.C. § 1314. The Court granted en banc review. For the reasons that follow, we find that the EPA did not act contrary to law or arbitrarily or capriciously in promulgating regulations for the Coal Remining Subcategory. I. Background A. Regulatory Landscape The United States is divided into three major coal producing regions, termed the Appalachian, Interior, and Western regions. Historically, the Appalachian region accounted for approximately three-fourths of the total annual coal production. The Western Coal Region contains extensive deposits of sub-bituminous, low sulfur-content coal, which occurs in thick coal seams and shallow overburden conditions that allow for extraction at relatively low cost. Surface mine coal production has increased by more than ninety percent since 1970, and there have been dramatic changes in the domestic production of coal due to environmental concerns and market demands. The lack of environmental controls, until recently, has produced hundreds of thousands of acres of abandoned mine land. 65 Fed.Reg. 19,440, 19,444 (Apr. 11, 2000). The EPA estimates that there are currently over 1.1 million acres of abandoned coal mine lands in the United States, which have produced over 9,709 miles of streams polluted by acid mine drainage. Id. Roughly ninety percent of this acid mine drainage comes from coal mines abandoned prior to the passage of federal laws regulating pollution and reclamation of mined lands. Id. There are two principal pieces of federal legislation governing water pollution caused by coal mines. The Surface Mining Control arid Reclamation Act (“SMCRA”), 30 U.S.C. §§ 1201-1328, was enacted on August 3, 1977, to regulate the environmental impacts of coal mining. The SMCRA is administered by the Office of Surface Mining Reclamation and Enforcement (“OSMRE”) within the Department of the Interior. Title V of the statute gives the OSMRE broad authority to regulate specific management practices before, during, and after mining operations. The OSMRE has promulgated comprehensive regulations to control both surface coal mining and the surface effects of underground coal mining. See 30 C.F.R. §§ 700-955 (2005). The CWA was enacted in 1972 “to restore and maintain the chemical, physical, and biological integrity of the Nation’s waters.” 33 U.S.C. § 1251(a); see also BP Exploration & Oil, Inc. v. EPA, 66 F.3d 784, 789 (6th Cir.1995). The CWA prohibits the “discharge of any pollutant” by “any person” into navigable waters except as authorized by the Act. 33 U.S.C. § 1311(a). The Act is enforced through effluent limitations guidelines and National Pollutant Discharge Elimination System (“NPDES”) permits that set technology-based discharge limits for categories and subcategories of water pollution point sources. See 33 U.S.C. § 1342. The EPA is charged with formulating and enforcing effluent limitations guidelines for classes and categories of pollutants. See 33 U.S.C. § 1311(b). An “effluent limitation” is “any restriction established by a State or the Administrator on quantities, rates, and concentrations of chemical, physical, biological, and other constituents which are discharged from point sources into navigable 'waters, the waters of the contiguous zone, or the ocean, including schedules of compliance.” 33 U.S.C. § 1362(H). The Act sets progressively more stringent technological standards that the EPA must use in setting those discharge limits. 33 U.S.C. § 1311(b)(1); BP Exploration, 66 F.3d at 789 .(“CWA directs EPA to institute progressively more stringent effluent discharge guidelines in stages.”). The EPA is directed to determine the degree of effluent reduction attainable for three levels of technology-best practicable control technology (“BPT”), best available technology economically feasible (“BAT”), and best conventional pollutant control technology (“BCT”). 33 U.S.C. § 1314(b)(1)(A), (b)(2)(A), (b)(4)(A). The EPA must also identify the factors it will consider when it makes these determinations. 33 U.S.C. § 1314(b)(1)(B), (b)(2)(B), (b)(4)(B). On April 26, 1977, the EPA issued final BPT effluent limitations guidelines for the Coal Mining Point Source Category. See 40 C.F.R. § 434. The regulations established limitations for the discharge of iron, manganese, suspended solids, settleable solids, and the pH of wastewaters for existing sources. 42 Fed.Reg. 21,380 (Apr. 26, 1977). In 1985, the EPA amended the effluent limitations guidelines and created four subcategories for the Coal Mining Point Source Category. They were: 1)Coal Preparation Plants and Coal Preparation Plant Associated Areas 2) Acid or Ferruginous Mine Drainage 3) Alkaline Mine Drainage 4) Post Mining Areas. 50 Fed.Reg. 41,296 (Oct. 9,1985). The 1985 regulations did not include a subcategory for coal mining operations that sought to remine previously mined, but later abandoned, lands. Thus, the regulations for mining virgin lands applied to previously mined, abandoned lands. The applicable effluent limitation guideline for remining operations in the Appalachian region was 40 C.F.R. Pt. 434, Subpt. C, Acid or Ferruginous Mine Drainage, and the applicable guideline for reclamation activities in the West was 40 C.F.R. Pt. 434, Subpt. E, Post-Mining Areas. Further, for western coal mining operations, numeric limitations were based on the use of sedimentation pond technology that applied to all reclamation areas throughout the United States, without consideration of differences in climate, topography, or other factors. Application of these guidelines created a disincentive to potential reminers of abandoned mines because of the prohibitive cost of bringing pre-mined lands to the same standard as virgin lands, often re-suiting in untreated pollution for “pre-ex-isting discharges.” B. The Rahall Amendment To counter this disincentive, Congress added as part of the 1987 amendments to the CWA section 301(p), known as the Rahall Amendment after its sponsor, West Virginia Rep. Nick Rahall. This amendment sought to provide incentives for re-mining and reclaiming abandoned mine lands that pre-dated the SMCRA in 1977 by exempting certain remining operations from effluent limitations, thereby making remining economically feasible. Section 301(p) provides in pertinent part: Subject to paragraphs (2) through (4) of this subsection, the Administrator, or the State in any case which the State has an approved permit program under section 1342(b) of this title, may issue a permit under section 1342 of this title which modifies the requirements of subsection (b)(2)(A) of this section with respect to the pH level of any pre-existing discharge, and with respect to pre-exist-ing discharges of iron and manganese from the remined area of any coal re-mining operation or with respect to the pH level or level of iron or manganese in any pre-existing discharge affected by the remining operation. Such modified requirements shall apply the best available technology economically achievable on a case-by-case basis, using best professional judgment, to set specific numerical effluent limitations in each permit. 33 U.S.C. § 1311(p)(l). In other words, the Rahall Amendment allows the Administrator or a State with an approved NPDES permitting program to issue a discharge permit that modifies the categorical coal mining effluent limitations for pH, iron, and manganese with respect to any “pre-existing discharges” from the re-mined area of any remining operation or affected by the remining operation. Where such a modified requirement is allowed, BAT is to be determined on a case-by-case basis, using the permit writer’s “best professional judgment” (“BPJ”), “to set the specific numerical effluent limitations in each permit.” Id. At the same time, under the Amendment, the Administrator may not issue a permit unless “the applicant demonstrates ... that the coal remining operation will result in the potential for improved water quality from the remining operation.” Id. § 1311(p)(2). Further, the Administrator is prohibited from issuing a permit that allows discharges that exceed pre-existing-discharge levels. Id. The Rahall Amendment also provides that no discharge “shall exceed State water quality standards established under section 1313 of this title.” Id. The Amendment defines “coal remining operation” as one “which begins after February 4, 1987, at a site on which c.oal mining was conducted before August 3, 1977,” id. § 1311 (p) (3) (A), and a “remined area” as “only that area of any coal remin-ing operation on which coal mining was conducted before August 3, 1977,” id. § 1311(p)(3)(B). Finally, the Amendment states that nothing in the coal remining provision was intended to “affect the application of the Surface Mining Control and Reclamation Act of 1977 to any coal remin-ing operation, including the application of such Act to suspended solids.” 33 U.S.C. § 1311(p)(4). Congressman Rahall described the Amendment’s purpose as follows: Throughout the Appalachian region abandoned coal mine lands exist which, due to erosion and acidic discharges, pose a serious threat to water quality. However, in many instances, coal re-mining is not economically and technically feasible because industry becomes liable for treating the preexisting water discharges under stringent national effluent guidelines. This coal remining provision will enable industry to enter abandoned coal mine sites and engage in mining under modified water quality standards established on a case-by-case basis. The end result of this effort will be the reclamation of the site and as such, as [sic] improvement in water quality over that which existed at the site prior to remining. 133 Cong. Rec. H 168 (daily ed. Jan. 8, 1987) (statement of Rep. Rahall). C. The Final Rule Despite the Rahall Amendment, coal mining companies and most states remained reluctant to pursue remining without formal EPA approval and guidelines. Thus, after notice and comment, the EPA promulgated the Final Rule on January 23, 2002. The Final Rule created two new subcategories under the Coal Mining Point Source Category and promulgated regulations for both. 1. Coal Remining Subcategory The first subcategory, known as the Coal Remining Subcategory, applies to “pre-existing discharges that are located within or are hydrologically connected to pollution abatement areas of a coal remin-ing operation.” 40 C.F.R. § 434.71(a) (2005). “Pre-existing discharge” is defined as “any discharge resulting from mining activities that have been abandoned prior to the time of a remining permit application.” . Id. § 434.70(c). A coal remining operation is “a coal mining operation at a site on which coal mining was previously conducted and where the site has been abandoned or the performance bond has been forfeited.” Id. § 434.70(a). The Coal Remining Subcategory requires every remining operator to create a site-specific Pollution Abatement Plan and submit it to the EPA or the authorized state agency. 40 C.F.R. § 434.72(a). The Pollution Abatement Plan must “identify characteristics of the pollution abatement area and the pre-existing discharges,” “be designed to reduce the pollution load from pre-existing discharges,” and “identify the selected best management practices (BMPs) to be used.” Id. The regulation further requires the plan to “describe the design specifications, construction specifications, maintenance schedules, criteria for monitoring and inspection, and expected performance of the BMPs.” Id. The Coal Remining Subcategory sets the effluent limitations for four pollutants: total iron, total manganese, net acidity, and TSS. 40 C.F.R. § 434.72(b)(1). The effluent limitation for each pollutant “[m]ay not exceed baseline loadings,” ■ or conditions that exist when remining commences. Id. However, if the EPA or state permitting authority finds that measuring baseline pollutant loadings is infeasible, and that remining “will result in significant improvement that would not otherwise occur,” then no measurable effluent limitations apply. Id. § 434.72(b)(2). Under the Final Rule, these Pollution Abatement Plans qualify as BPT, 40 C.F.R. § 434.72, and BAT, 40 C.F.R. § 434.73, and BCT, 40 C.F.R. § 434.74, for remining operators. Thus, the Coal Remining Subeategory differs from the Rahall Amendment in four ways. First, the definition of “coal remin-ing operation” is broader than the definition found in the Rahall Amendment, which limits sites eligible for the modified effluent limits to those sites on which the coal remining operation began after February 4, 1987, on a site where coal mining had been conducted before August 3, 1977, the effective date of the SMCRA. The Final Rule allows any coal mining operation at a site on which coal mining was previously conducted and where the site has been abandoned or the performance bond has been forfeited, to be eligible regardless of whether prior mining occurred before August 3, 1977 or thereafter. Second, although the Rahall Amendment lists only three pollutants for which modified requirements are available (pH, iron, and manganese), the Final Rule added suspended solids to the list of requirements that could be modified. Third, the Rahall Amendment bounded the modified requirements by requiring that where the categorical effluent limitations were not required, specific numerical effluent limitations representing a case-by-case determination of the BAT would be required in each permit. On the other hand, the Final Rule allows modified permits without setting numeric limitations representing case-by-case BAT. Finally, the Final Rule differs from the Rahall Amendment by applying the more stringent general standard instead of the modified requirements to pre-existing discharges that reminers commingle with discharges from active mining operations. 2. Western Alkaline Coal Mining Subcategory The second new subcategory, the Western Alkaline Coal Mining Subcategory, applies to “mine drainage from applicable areas of western coal mining operations.” 40 C.F.R. § 434.82(a). A “western coal mining operation” is “a surface or underground coal mining operation located in the interior western United States, west of the 100th meridian west longitude, in an arid or semiarid environment with an average annual precipitation of 26.0 inches or less.” 40 C.F.R. § 434.80(f). The Final Rule requires the operator to submit to the permitting authority “a site-specific Sediment Control Plan ... designed to prevent an increase in the average annual sediment yield from pre-mined undisturbed conditions.” 40 C.F.R. § 434.82(a). Similar to the Pollution Abatement Plans, each Sediment Control Plan “must identify best management practices (BMPs) and also must describe design specifications, construction specifications, maintenance schedules, criteria for inspection, as well as expected performance and longevity of the best management practices.” Id. The Western Alkaline Coal Mining Subcategory does not set any uniform standards for drainage at western coal mining operations; it merely requires a Sediment Control Plan that is incorporated into the NPDES permit. However, operators must demonstrate “[ujsing watershed models,” that the Sediment Control Plans “will result in average annual sediment yields that will not be greater than the sediment yield levels from pre-mined, undisturbed conditions.” 40 C.F.R. § 434.82(b). The operator’s only other obligation is to implement and maintain the best management practices described in the Sediment Control Plan. Id. § 434.82(c). These include BPT, id., § 434.82; BAT, id. § 434.83; and BCT, id. § 434.84. The Western Alkaline Coal Mining Subcategory differs from the Rahall Amendment in that the effluent limitations on the concentration of settleable solids and pH have been eliminated, and replaced only with a requirement that the operator submit a site-specific Sediment Control Plan that is designed to prevent an increase in the “average annual sediment yield from pre-mined, undisturbed conditions” using “best management practices.” D. Litigation Petitioners brought this appeal under section 509(b) of the CWA, challenging the Final Rule. Petitioners claimed that the remining guidelines exceeded EPA’s statutory authority under the Rahall Amendment by expanding both the number of sites and the number of pollutants eligible for modified pollutant limits, and that the new rule impermissibly discourages remin-ing at Rahall-eligible mines by subjecting commingled waste streams to the most stringent effluent limitation applicable to the constituent waste streams. Regarding the Western Alkaline Coal Mining Subcategory, Petitioners first argued that BMPs are not appropriate effluent limitations because they are not numeric criteria. Second, they claimed that the Administrator has not shown that continued imposition of the currently applicable effluent limitations is infeasible. Third, they argued that the entire subcategory of Western Alkaline Coal Mining is irrational. Finally, Petitioners contended that the EPA’s goal in creating the subcategory is inconsistent with the CWA and the SMCRA. The EPA defended the Final Rule on the grounds that the Rahall Amendment does not limit its authority to issue the regulations. The EPA argued that the requirement of “best management practices” in lieu of numeric effluent limitations was a reasonable exercise of its authority. As to the Western Alkaline Coal Mining Subcategory, the EPA argued that numeric limitations were infeasible. The EPA also maintained that the creation of the subcategory was not arbitrary or capricious because it had relied on scientific information to support its creation. Finally, the agency asserted that setting effluent limitations at premined background levels was consistent with the CWA and the SMCRA. E. Panel Decision A panel of this Court unanimously rejected Petitioners’ arguments that the Ra-hall Amendment deprived the EPA of authority to promulgate the Coal Remining regulations. See Citizens Coal Council v. EPA, 385 F.3d 969 (6th Cir.2004), vacated, reh’g en banc granted, February 23, 2005. It reviewed the EPA’s construction of the statute under Chevron, U.S.A. v. Natural Res. Def. Council, Inc., 467 U.S. 837, 104 S.Ct. 2778, 81 L.Ed.2d 694 (1984), and concluded that neither the Rahall Amendment nor the CWA itself addressed whether the EPA could create additional subcategories. The unanimous panel further held that the Amendment was simply an opt-out provision, and that it did not address the EPA’s authority to promulgate regulations that are broader than its provisions. The panel therefore held that the EPA’s interpretation that 33 U.S.C. § 1314(b) grants it independent authority to issue the regulations was reasonable under Chevron. The majority nonetheless found the regulations invalid on grounds not raised or presented by either party. First, the majority found the regulations invalid because the EPA failed to follow procedures the majority deemed required by law. Specifically, the majority found that, as the very first step in the development of any effluent limitations guidelines under 33 U.S.C. § 1314, the EPA must “identify which control measures and practices are available to the various categories and classes of point sources” under 33 U.S.C. § 1314(b)(3). The majority found that the EPA had impermissibly skipped this mandatory step for the Coal Remining regulations because the EPA first defined the desired level of pollution (baseline conditions) and then worked backwards to find technological tools (site-specific plans) that would achieve this goal. The majority further reasoned that the EPA’s approach shirked its obligation under 33 U.S.C. § 1314(b)(1)(A), (b)(2)(A) and (b)(4)(A) to determine the degree of effluent reduction attainable. The majority faulted the EPA for setting the required reduction at zero (the baseline) without determining if a greater reduction was possible. The court held that “where the EPA fails to determine how much reduction in pollution is possible, and to do so by reference to the amounts of pollutants,” it deviates from the statutory directive. The majority also faulted the Coal Remining regulations because the regulations impermissibly set effluent limitations through site-specific factors. Finally, the majority invalidated the Coal Remining regulations because the record contained no evidence that the EPA considered each of the factors enumerated in 33 U.S.C. § 1314(b)(1)(B), (b)(2)(B), and (b)(4)(B). The panel majority invalidated the Western Alkaline Coal Mining Subcategory on the same bases. One member dissented from those portions of the majority opinion that found the EPA’s regulations invalid, and would have upheld the regulations in their entirety. The EPA sought en banc review, arguing that the court should not have reached the issues upon which the panel majority ruled against the EPA, because those issues were neither raised to the EPA in the underlying notice-and-comment rulemak-ing proceeding, nor in Petitioners’ initial brief. The EPA also contended that the panel erred by not deferring to its reasonable construction of ambiguous provisions of a statute it administers. The EPA therefore asked that this Court vacate those portions of the panel majority’s decision in which it found the regulations invalid. II. Standards of Review A. Statutory Interpretation In Chevron, the Supreme Court articulated a two-step test for judicial review of an agency’s interpretation of a statute. First, the reviewing court must ask “whether Congress has directly spoken to the precise question at issue.” Id. at 842, 104 S.Ct. 2778. If so, “that is the end of the matter; for the court, as well as the agency, must give effect to the unambiguously expressed intent of Congress.” Id. at 842-43, 104 S.Ct. 2778 (footnote omitted). If Congress has not directly spoken to the issue at hand, however, the court must decide if the agency’s action under the statute is based on a permissible construction of the statute. Id. at 843, 104 S.Ct. 2778. In this second step, the court must accord considerable weight to the agency’s construction of the statute and it may not substitute its own construction of the statute for the agency’s reasonable interpretation. Id. at 843-44, 104 S.Ct. 2778. B. Agency Discretion The EPA promulgated the Final Rule through informal rulemaking. The scope of our review over the informal rulemaking process is generally governed by section 10(2)(e) of the Administrative Procedure Act (“APA”), 5 U.S.C. § 706(2) (1996). BP Exploration, 66 F.3d at 792. Under § 706(2), a court must invalidate an informal rule if it is “arbitrary, capricious, an abuse of discretion, or otherwise not in accordance with law”; “in excess of statutory jurisdiction, authority, or limitations, or short of statutory right”; or “without observance of procedure required by law.” 5 U.S.C. § 706(2)(A), (C), (D). An agency rule is “arbitrary or capricious” 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 Ass’n v. State Farm Mut. Auto. Ins. Co., 463 U.S. 29, 43, 103 S.Ct. 2856, 77 L.Ed.2d 443 (1983). The court is required to make a “searching and careful review” in its assessment of the agency action, but “the ultimate standard of review is a narrow one.” Citizens to Preserve Overton Park, Inc. v. Volpe, 401 U.S. 402, 416, 91 S.Ct. 814, 28 L.Ed.2d 136 (1971). Where the rulemaking involves review of the agency’s technical or scientific evaluations and determinations, the highest level of deference to the agency is to be applied. Baltimore Gas & Elec. v. Natural Res. Def. Council, Inc., 462 U.S. 87, 103, 103 S.Ct. 2246, 76 L.Ed.2d 437 (1983); BP Exploration, 66 F.3d at 792. III. Analysis A. Coal Remining Subcategory 1. Chevron Analysis In their original merits brief, Petitioners contended that, in creating the Final Rule, the Administrator violated step one of Chevron by ignoring the language and intent of section 301 (p) of the Rahall Amendment. They claim that the Rahall Amendment precisely defined the limited circumstances in which a modified permit may be issued in lieu of the otherwise-applicable categorical effluent limitations for coal mining operations, and that the Final Rule exceeds these boundaries in numerous respects. Specifically, Petitioners contended that Congress bounded the EPA’s authority by specifying which pollutants (pH, iron, and manganese) are eligible for relaxed standards, which operations (pre-August 3, 1977) are eligible, what limits must apply in place of national guideline limits (i.e. specific numerical limits), and when the alternative standards would apply. Thus, the initial question under step one of Chevron is whether the Rahall Amendment itself or the CWA otherwise explicitly addresses the Administrator’s authority to create a subcategory under the Coal Mining Point Source Category and to promulgate regulations for that subcategory that conflict with the Rahall Amendment. The Rahall Amendment states that the Administrator “may issue a permit under section 1342 of this title which modifies the requirements of subsection (b)(2)(A) of this section” with respect to certain effluents. 33 U.S.C.A. § 1311(p) (emphasis added). Section 301(b)(2)(A) in turn provides for “effluent limitations for categories and classes of point sources ... which will result in reasonable further progress toward the national goal of eliminating the discharge of all pollutants, as determined in accordance with regulations issued by the Administrator.” Id. § 1311(b)(2)(A). The Rahall Amendment, therefore, provides for modifications of the effluent limitations guidelines determined by the Administrator for categories and classes of point sources pursuant to the requirements of sections 301(b) and 304(b). The Amendment is permissive; it does not require remining operations to seek such modified permits, and remining operators remain free to seek permits under the generally applicable effluent limitations guidelines promulgated by the EPA pursuant to section 304(b). The Rahall Amendment says nothing about the EPA’s ability or inability to regulate national effluent limitations. It simply provides express authority to modify individual NPDES permits on a case-by-case basis to allow ef-. fluent limitations for specified pollutants in the pre-existing discharges from remining operations other than those required in the generally applicable effluent limitation regulations found in 40 C.F.R. § 434, Subpt. C. Sections 301(b) and 304(b) also do not provide a definitive answer. Section 304(b) states that the “Administrator shall ... publish ... regulations ... providing guidelines for effluent limitations, and, at least annually thereafter, revise, if appropriate, such regulations” for various classes and categories of point sources. 33 U.S.C.A. § 1314(b) (emphasis added). Section 301 gives these guidelines the force of law, id. at § 1311(a) (“Except as in compliance with this section ... the discharge of any pollutant by any person shall be unlawful”); § 1311(e) (“Effluent limitations established pursuant to this section or section 1312 of this title shall be applied to all point sources of discharge of pollutants in accordance with the provisions of this chapter.”), and section 402(a) (33 U.S.C. § 1342) directs the Administrator to incorporate these regulations into NPDES permits issued to individual polluters. Neither section 301(b) nor 304(b) contains any restriction vis-a-vis section 301 (p) on the Administrator’s power to create additional subcategories for the Coal Mining Point Source Category. In short, these sections do not express a clear congressional intent on the issue of whether the EPA has the power to create a subcategory that differs from the Rahall Amendment. Petitioners assert that the EPA cannot rely on its general rulemaking authority when specific statutory directives define how that standard-setting authority is to be used in a particular instance. See, e.g., Am. Petroleum Inst. v. EPA, 52 F.3d 1113, 1119 (D.C.Cir.1995) (stating that the “EPA cannot rely on its general authority to make rules necessary to carry out its functions when a specific statutory directive defines the relevant functions of EPA in a particular area”) (citations omitted). That is, they claim that the Rahall Amendment’s directives as to which pollutants, which operations, what limits, and when alternative standards apply preclude the EPA from adopting standards that are inconsistent with these limitations. However, because the Rahall Amendment does not contain a specific statutory directive to limit or prevent the EPA from otherwise exercising its. statutory authority to establish national standards for the remining subcategory, this argument is unavailing. Because Congress has not directly addressed the precise question at issue, we move to step two of the Chevron analysis. Chevron, 467 U.S.. at 843, 104 S.Ct. 2778. The EPA claims that it was authorized to promulgate regulations for the coal remin-ing subcategory pursuant to its general rulemaking authority under section 304(b), and that nothing in section 301(p) limits that authority, because the Rahall Amendment is simply a permissive, opt-out, rather than a generally applicable, scheme. As noted, section 304(b) authorizes, indeed requires, the Administrator to create effluent limitation guidelines for various classes and categories of point sources. When considered with the permissive, opt-out nature of the Rahall Amendment, applicable in individual permits, we cannot say that the Administrator’s conclusion that it was authorized to create additional subcategories under the Coal Mining Point Source Category, not identical to the Ra-hall Amendment, was unreasonable. We also find that the EPA did not act arbitrarily or capriciously in promulgating the Final Rule. The record reflects that, despite the Rahall Amendment, remining operations were not occurring. The Final Rule was issued fifteen years after the Rahall Amendment. In the first ten years after its enactment, only 330 (out of 1072) Rahall-type permits had been issued, with 300 of those being issued by Pennsylvania. Many states had not been able to establish the guidelines and procedures required to issue Rahall permits. At the same time, “IMCC member States [had] indicated that they would be able to establish formal remining programs under guidelines set forth under an EPA effluent limitations Coal Remining subcategory,” and that with such guidelines, “mine operators would be more inclined to enter into remining projects.” 65 Fed.Reg. at 19,445. The EPA promulgated the rule in the hopes of providing “better environmental results than the [then-] current requirements.” Id. at 19,446. Thus, the EPA had a reasonable basis for its action-namely evidence that the Rahall Amendment was, as a practical matter, not achieving its goal of encouraging remining and, on a larger scale, of restoring the “chemical, physical, and biological integrity of the Nation’s waters.” 33 U.S.C. § 1251(a). The EPA’s conclusion that remining has many potential benefits is also supported in the record. Id. at 3375. Performing statistical analyses to evaluate the effects of remining on water quality at thirteen remining sites, the EPA analyzed the adverse environmental impacts of current practices as a basis for assessing the incremental environmental impacts of the proposed rule. Id. at 3389; Kristen L. Strellec, Office of Water, Office of Sci. and Tech., Eng’g and Analysis Div., Envtl. Prot. Agency, EPA 821-B-00-002, Effluent Limitations Guidelines and Standards for the Coal Mining Industry: Re-mining and Western Alkaline Subcategories 8-l(Mar.2000), available at http:// mvw.epa. gov/guide/coal/ impactpdf. The EPA observed that abandoned mine lands are associated with a wide range of public health and safety problems and aesthetic degradation, including abandoned mine openings, highwalls, unstable spoil piles, and hazardous water bodies. In addition, acid mine drainage from abandoned mine lands causes serious water quality problems because of its high acidity and other contaminants. Id. Remining improved water quality through the removal of acid-forming materials and sediment, improved public safety by correcting problems associated with abandoned mines, and improved the aesthetic quality of the land and water resources. Id. at 8-1 to 8-3. In sum, the decision to establish national standards for the remining subcategory was not contrary to the plain language of section 301 (p), was within the Administrator’s broad discretion under sections 301(b) and 304(b), is supported by the record, and was not unreasonable. 2. Specific Challenges Having rejected the argument that the EPA lacked authority to promulgate the Final Rule, and further concluded that the EPA’s interpretation of the Act as allowing it to create subcategories under the Coal Mining regulation was reasonable, we now address Petitioners’ challenges to specific aspects of the remining subcategory rule. a. Definition of “Coal Remining Operation” Petitioners complain that the EPA exceeded its authority in defining “coal remining operation” to include remining operations on mine lands abandoned after August 3,1977. For the reasons discussed above, the EPA was not constrained to use a definition identical to the definition of “coal remining operation” in the Rahall Amendment. Furthermore, as explained above, the EPA’s reading of the Act as giving it authority under section 304(b), together with section 301(b), is not unreasonable. We also find that the EPA did not act arbitrarily or capriciously in deciding to extend the applicability of the coal mining subcategory effluent limitations guidelines beyond those remining operations that had been previously eligible for modified permits under section 301(p). The record reflects that the EPA examined whether the broader definition would cause an increase in abandoned mines in order to take advantage of the remining effluent limitation guidelines for pre-existing discharges at a future remining operation. 67 Fed.Reg. at 3374. However, the EPA concluded that there are strong disincentives under the SMCRA against mine operation abandonments. Id. A mine operator not only forfeits the reclamation bond, but is also precluded from receiving further mining permits until reclamation is completed. Thus, it cannot be said that the EPA acted arbitrarily or capriciously in adopting a broader definition of “coal remining operation” than that found in the Rahall Amendment. b. TSS Petitioners contend that section 301(p) does not allow modified NPDES permit limits for TSS. In support, they cite section 301(p)(4), which states that “[n]othing in this subsection shall affect the application of the Surface Mining Control and Reclamation Act of 1977 ... to any coal remining operation, including the application of such Act to suspended solids.” 33 U.S.C. § 1311(p)(4). Again, nothing in the Rahall Amendment limits or even addresses the EPA’s discretion to promulgate national standards. The quoted language refers to the SMCRA only, and Petitioners offer no explanation as to how including effluent limitations for suspended solids affects the application of SMCRA requirements for suspended solids. Further, the record reflects that the EPA considered whether the alternative limits for solids would square with the SMCRA requirements for suspended solids, and concluded that “the final regulation is consistent with SMCRA which mandates the prevention of additional contribution of suspended solids to stre-amflow to the extent possible using the best technology currently available.” 67 Fed.Reg. at 3388. The EPA explained that it has adopted what is essentially a compliance schedule so that, during remining and reclamation activities, the operator cannot contribute sediment levels beyond the baseline discharge loading. After remining and reclamation has been completed, the operator must meet the standards for TSS and SS contained in subpart E-Post Mining areas prior to bond release. EPA concluded that the implementation of successful sediment control BMPs should, in most cases, be able to meet the BPT standards contained in subpart E-Post Mining areas regardless of whether the area has been disturbed due to remining or virgin mining. Id. Nor is including effluent limitations for solids inconsistent with the purpose of section 301(p). The record reflects that the EPA initially did not propose alternative limits for solids, but based on comments and information received on the proposed rule, the EPA decided that alternative limits for pH, iron, and manganese, but not for solids, would not provide sufficient incentives for remining abandoned mine lands. The EPA noted that the alternative limits for suspended solids were consistent with the intent of the Rahall Amendment, “which seeks to encourage remining while ensuring that the remining will potentially improve and reclaim [abandoned mine lands].” Id. Thus, the EPA’s inclusion of TSS in the coal remining subcategory was not arbitrary or capricious. c. BMPs Petitioners also argue that the EPA lacks authority to promulgate BMPs in place of numerical standards as effluent limitations, because section 301 (p) provides that modified permits under the Rahall Amendment apply BAT on a case-by-case basis “to set specific numerical effluent limitations in each permit.” 33 U.S.C. § 1311(p)(l) (emphasis added). Again, for the reasons articulated above, section 301(p) does not limit the EPA’s authority to use BMPs. The EPA contends that its interpretation was reasonable because the CWA does not mandate the use of numeric limitations only. The EPA therefore claims that it reasonably determined that effluent limitations for iron, manganese, acidity, and/or TSS from pre-existing discharges from coal remining operations may take the form of BMPs when a baseline pollutant loading cannot be calculated. The EPA relies on the definition of “effluent limitation,” which is defined under the Act as any restriction established by a State or the Administrator on quantities, rates, and concentrations of chemical, physical, biological, and other constituents which are discharged from point sources into navigable waters, the waters of the contiguous zone, or the ocean, including schedules of compliance. 33 U.S.C. § 1362(11) (emphasis added); see also 33 U.S.C. § 1312(a) (stating that “[w]henever, in the judgment of the Administrator ... discharges of pollutants from a point source or group of point sources, with the application of effluent limitations required under section 1311(b)(2) of this title, would interfere with the attainment or maintenance of that water quality in a specific portion of navigable waters ... effluent limitations (•including alternative effluent control strategies) for such point sources or sources shall be established which can reasonably be expected to contribute to the attainment or maintenance of such water quality”) (emphasis added). Thus, under the Act, effluent limitations are not limited to numeric discharges but encompass “any restriction” on discharges, including “schedules of compliance,” or “a schedule of remedial measures including an enforceable sequence of actions or operations leading to compliance with an effluent limitation.” 33 U.S.C. § 1362(17). The EPA’s reading of the Act finds support in the language of the Act and is therefore not unreasonable. Other courts have also recognized that the CWA does not require the EPA to set numeric limits where such limits are infeasible. See, e.g., Waterkeeper Alliance, Inc. v. EPA 399 F.3d 486, 502 (2d Cir.2005) (stating that site-specific BMPs are effluent limitations under the CWA; holding that the EPA provision regulating the emission of water pollutants by concentrated animal feeding operations was arbitrary and capricious because it allowed permitting authorities to issue permits that did not include terms of nutrient management plans, in violation of CWA requirement that effluent limitations be included in NPDES permits); Natural Res. Def. Council, Inc. v. EPA 673 F.2d 400, 403 (D.C.Cir.1982) (noting that “section 502(11) defines ‘effluent limitation’ as ‘any restriction’ on the amounts of pollutants discharged, not just a numerical restriction”; holding that section of CWA authorizing courts of appeals to review promulgation of “any effluent limitation or other limitation” did not confine the court’s review to the EPA’s establishment of numerical limitations on pollutant discharges, but instead authorized review of other limitations under the definition) (emphasis added). In Natural Res. Def. Council, Inc. v. Costle, 568 F.2d 1369 (D.C.Cir.1977), the D.C. Circuit stressed that when numerical effluent limitations are infeasible, EPA may issue permits with conditions designed to reduce the level of effluent discharges to acceptable levels. This may well mean opting for a gross reduction in pollutant discharge rather than the fine-tuning suggested by numerical limitations. Id. at 1380 (rejecting the EPA’s argument that where it was infeasible to promulgate numeric effluent limitations, the EPA was authorized to exclude the relevant point source from the NPDES program, because section 402(a) gives the EPA considerable flexibility in framing the permit to achieve a desired reduction in pollutant discharges); see also id. at 1380 n. 21 (noting the proposition that Congress did not regard numeric effluent limitations as the only permissible limitation was supported by section 302(a) of the Act, 33 U.S.C. § 1312(a)). Petitioners contend that the suggestion that best management practices are the equivalent of effluent limitations “flies in the face of the distinction drawn by Congress in Section 304(e) and 304(b).” Section 304(e) authorizes BMPs as “supplemental” to effluent limitations. See 33 U.S.C. § 1314(e) (stating that the EPA “may publish regulations, supplemental to any effluent limitations specified under subsections (b) and (c) of this section for a class or category of point sources, for any specific pollutant which the Administrator is charged with a duty to regulate as a toxic or hazardous pollutant”). Petitioners therefore claim that BMPs alone may not constitute effluent limitations. The EPA counters that section 304(e) applies specifically to toxic pollutants, and maintains that it derives independent authority under sections 402(a) and 304(b), 33 U.S.C. §§ 1342(a), 1314(b), and section 502(11), 33 U.S.C. § 1362(11) to incorporate BMPs in the effluent guidelines for other pollutants. Thus, the EPA maintains that sections 502(11), 304(b), and 304(e) can be read together as allowing BMPs as supplemental to an effluent limitation under § 304(b), or can each stand as an effluent limitation by itself. This is certainly not an unreasonable interpretation of the Act, and given the ambiguity in the CWA on this point, we will uphold the EPA’s interpretation as reasonable. In any event, the effluent limitations guidelines are consistent with section 301(p)(l) in that they require numerical limitations to be included in the NPDES permits, unless calculation of such numeric limits is infeasible. See 40 C.F.R. § 434.72(b)(1) (“Except as provided in ... paragraph (b)(2) of this section, the following effluent limits apply to pre-existing discharges .... ”). Further, the required numerical limitations are consistent with section 301(p)(2), which states that limitations for pH, iron, and manganese cannot allow discharge of such pollutants “to exceed the levels being discharged from the remined area before the coal remining operation begins.” Under the coal remining subcategory, the EPA interpreted the Ra-hall Amendment’s requirement not to exceed baseline “levels” as a requirement not to exceed a pollutant baseline “loading.” 67 Fed.Reg. at 3384. Thus, determining specific effluent limitations requires calculating baseline pollutant loadings for each pollutant in the pre-existing discharge, using a standardized procedure for the calculation. See 40 C.F.R. § 434, app. B (“Baseline Determination and Compliance Monitoring for Pre-Existing Discharges at Remining Operations”). The calculation becomes the numerical limitation for the pollutant. Non-numeric limits are allowed only when numeric limits are infeasible. Finally, the remining subcategory rule requires non-numeric effluent limitations consisting of a pollution abatement plan, which “must be designed to reduce the pollution load from pre-existing discharges and must identify the selected best management practices (BMPs) to be used.” 40 C.F.R. § 434.72(a). This requirement is consistent with section 301(p), which requires the coal remining operator to demonstrate “that the coal remining operation will result in the potential for improved water quality from the remining operation.” In sum, the EPA’s inclusion of numeric and non-numeric limitations in the guideline for the coal remining subcategory was a reasonable exercise of its authority under the CWA. d. Intercepted and Commingled Discharges Petitioners also complain that the Final Rule ignores the language and intent of the Rahall Amendment by requiring a pre-existing discharge that is “intercepted by active mining or that is commingled with waste streams from active mining areas for treatment” be subject to the higher categorical standards for commingling of waste streams found in 40 C.F.R. § 434.61. 40 C.F.R. § 434.71(b). Thus, the availability of the alternative standards under the Final Rule is limited to discharges that are relocated or diverted, and to pre-existing discharges “[a]fter commingling has ceased.” Id. Petitioners contend that the Final Rule conflicts with the language in the Rahall Amendment stating that modifications shall be allowed “from the remined area of any coal remining operation ... qr in any pre-existing discharge affected by the remining operation.” 33 U.S.C. § 1311(p)(.l). In other words, Petitioners contend that this regulation is too strict. The EPA responds that this language does not contemplate that active mining discharges will necessarily have to be commingled with the pre-existing discharges at remining sites. Thus, according to the EPA, Petitioners’ reading would actually broaden the scope of permit modifications authorized by section 301 (p) by applying the grant of authority to discharges from the entire remining operation rather than to pre-existing discharges only. The EPA further contends that the permit modification authority applies only to the pre-exist-ing discharges and not to discharges resulting from the active mining activities of a remining operation, citing 33 U.S.C. § 1311(p)(l), (p)(3)(C).. As previously discussed, the Rahall Amendment does not prohibit the EPA from applying its general commingling rule to commingling of pre-existing discharges. See 40 C.F.R. § 434.61. Further, as the EPA notes, the term “pre-existing-discharge” is defined in section 301(p)(3)(C) as “any discharge at the time of permit application,” or in other words, those discharges in existence prior to the start of remining. The phrase “in any preexisting discharge affected by the remin-ing operation” is ambiguous, and we cannot say that-the EPA’s interpretation of this provision is inconsistent with section 301(p) and therefore unreasonable. We therefore defer to the EPA’s construction of its own regulations. Lastly, Petitioners assert that section 402(1)(2), 33 U.S.C. § 1342(1)0), bars applying effluent limitations guidelines to pre-existing discharges that are diverted in order to avoid interception by or commingling with active mining discharges. This argument makes no sense. Section 402(1)(2) provides an exemption from the requirement for a permit for “discharges of stormwater runoff from mining operations ... which are not contaminated by contact with, or do not come into contact with, any overburden, raw material, '... byproduct or waste products located on the site of such operations.” 33 U.S.C. § 1342(1)0). Pre-existing discharges at remining sites are highly contaminated as a result of contact with the raw materials, overburden, and waste products of prior mining activities. And, section 301(p) inherently recognizes that pre-existing discharges are subject to NPDES permit requirements. In short, the EPA’s decision to apply an existing regulation rather than the Final Rule to waste streams that have been commingled was within its discretion and not unreasonable. e. Response to Dissent The dissent’s primary argument is that the EPA’s decision to set effluent reduction attainable at zero for remining areas was arbitrary and capricious. The dissent asserts that, “[b]y requiring remining operators to preserve only the status quo, the EPA undermines the potential for reduction that is available and required under the Clean Water Act.” This argument overlooks the whole point of not only the Final Rule, but the Rahall Amendment itself. The Rahall Amendment was enacted based upon congressional findings that remining and reclamation were not occurring due to prohibitive cost of meeting effluent limitations guidelines applicable to virgin lands. The Final Rule was promulgated because the Rahall Amendment had not proven effective in encouraging remin-ing. In setting the effluent reduction attainable at zero, the Final Rule took its cue from the Rahall Amendment itself, which set the baseline at zero. See 33 U.S.C. § 1311(p)(2) (stating that “in no event shall such a permit allow the discharges of iron and manganese, to exceed the levels being discharged from the re-mined area before the coal remining operation begins”). Furthermore, although the Final Rule sets the effluent limitation for each pollutant as not to exceed “baseline loadings,” the Coal Remining Subcategoiy at the same time requires every remining operator to create a site-specific Pollution Abatement Plan that is “designed to reduce the pollution load from pre-existing discharges.” 40 C.F.R. § 434.72(a). The dissent also contends “there is no evidence that the EPA ever explored the prospect of accomplishing more than preserving the status-quo” in attempting to meet the Act’s goal of eliminating the discharge of all pollutants. However, as the EPA points out and the record reflects, the EPA considered available technology in several ways prior to the enactment of the Coal Remining Subcategory. Prior to promulgating the Final Rule, the EPA was aware that the technologies underlying the existing effluent limitations for the Coal Mining Category were not effective in reducing pollution from abandoned mines, because remining under the regulations and available technology was not occurring, even after the Rahall Amendment. 65 Fed.Reg. at 19,448. In addition, the EPA performed a specific analysis of forty remining sites to determine if application of the existing effluent limitations would be cost effective. Id. at 19,446. The EPA performed a cost comparison analysis of the forty remining sites submitted by the State of Pennsylvania and determined that in all forty cases, remining was deemed not economically feasible if the pre-existing discharges were required to meet the existing effluent limitations. Id. Furthermore, the EPA considered the reductions that could be achieved through BMP technology. Specifically, it reviewed data submitted from the State of Pennsylvania from 112 closed remining sites operating under Rahall permits, representing tile most extensive data currently available for assessment of the water quality impacts of BMP implementation at remining operations. Id. at 19,447. This study showed that implementation of appropriate BMPs was effective in improving or eliminating acidity loading in 45% of the preexisting discharges, total iron loading in 44% of the discharges, and total manganese in 42% of the discharges. Id. at 19,448. The annual combined reductions in pollutant loadings from the BMPs equaled 5.8 million pounds of acidity, 189,000 pounds of iron, and 11,400 pounds of manganese. Id. The EPA also examined thirteen active remining operations included in its Coal Remining Database and determined that roughly 58% showed a decrease in mean pollutant loadings and approximately 50% showed a decrease in pollutant loadings after the implementation of BMPs. 67 Fed.Reg. at 3389. Finally, the EPA specifically discussed the available technology for coal remining in its consideration of the various levels of control under section 304(b). 67 Fed.Reg. 3370, 3379-80. Regarding BAT, the EPA concluded that there was only one available technology that was more stringent than the BMPs, namely pre-existing treatment, but that it was not economically feasible for remining sites. Id. at 3379. This was also true for BPT, where the EPA determined that pollutant abatement plans represented the average of the best technology currently available due to Pennsylvania’s experience in employing BMPs in Rahall permits. Id. at 3380. As for BCT, the EPA applied its BCT cost-effectiveness test and determined that there are “no technologies that can achieve greater removals of conventional pollutants than established for BPT that are also cost-reasonable under the BCT costs test.” Id. Finally, as for “elimination” of pollutants, the EPA noted that “zero [pollutant] loadings are expected to occur, at least for some remining sites, after regrading and contouring when discharge flows may be reduced greatly”; and that “zero flows have been observed after remining at some mine sites.” Id. at 3385. This, however, had occurred in only a small percentage of facilities and was therefore not identified as an attainable effluent limitation for BPT, BAT, or BCT. See Office of Water, Office of Sci. and Tech. Eng’g and Analysis Div. Envtl. Prot. Agency, Coal Remining — Best Management Practices Guidance Manual, EPA 821-B-01-010, at 6-8 (2001), available at http://epa.gov/guide/coal/bmp /section6.pdf (last visited May 4, 2006) (chart showing overall percentages of discharges achieving varying levels of water quality improvements from the implementation of BMP technology). Thus, contrary to the dissent’s position, the EPA determined that the pre-existing technology had resulted in little discharge reductions and therefore no environmental improvement, because the industry was not engaging in remining. Because BMP technologies had been proven to reduce pollutant loadings at remining sites, the EPA deemed it preferable to allow the use of BMPs rather than no action. This reading is entirely consistent with the CWA’s goal of eliminating water pollution. The EPA’s decision to set the effluent reduction attainable at zero was not arbitrary or capricious. B. Western Alkaline Coal Mining Subcategory The Western Alkaline Coal Mining Subcategory adopts alternative sediment control technologies for reclamation areas at coal mining sites in the arid West. Petitioners argued the EPA lacked authority to eliminate effluent limitations and replace them with BMPs, and, even if it has that authority, the EPA failed to demonstrate that continued imposition of the current effluent limitations for settleable solids and pH is infeasible. Petitioners further contend that the subcategory is overbroad, irrational, and inconsistent with the CWA and the SMCRA. 1. Authority Petitioners contend that allowing BMPs instead of numeric effluent limitations in NPDES permits for Western Alkaline Coal Mine reclamation sites is contrary to the CWA. Again, for the reasons discussed elsewhere in this opinion, this argument is rejected. 2. Infeasibility Petitioners also contend that the EPA failed to demonstrate that continued use of current effluent limitations for settleable solids and pH is infeasible, and that replacing them with BMPs was not supported by the record and was arbitrary and capricious. The EPA states that the administrative record supports its determination that numeric limits are infeasible because, in order to comply with these limits, the operator of a reclaimed mine site must use a sedimentation pond, and these ponds have serious non-water quality impacts in the arid West that may harm the environment. In the proposed rule the EPA stated that although sedimentation ponds are proven to be effective at reducing sediment discharge, in some instances they promoted negative environmental impacts in the arid and semiarid western regions. 65 Fed. Reg. at 19,453. Sedimentation ponds in reclamation areas are designed to capture and store water from a precipitation event and then slowly release the water in a continuous, low-velocity discharge. The EPA remarked that the slow release of water containing low amounts of sediment has caused negative environmental impacts in arid regions, including disruption of the natural hydrologic and sediment balance, stream channel instability, and water loss due to evaporation. Id. The EPA explained that, in arid and semiarid western coal mine regions, the natural vegetative cover is sparse and rainfall typically occurs during localized, high-intensity, short-duration storms. These conditions contribute to flash floods and turbulent flows that transport large amounts of sediment that may contain up to several hundred thousand milligrams per liter of total suspended solids. Furthermore, fluvial areas and receiving channels in the arid west have developed according to these natural conditions. The receiving channels consist primarily of ephemeral arroyos that transport large volumes of f