dissenting.
I respectfully dissent. The practical effect of the majority opinion is to hold that if a pollution discharge is not expressly forbidden by the FWPCA, EPA regulations or state-adopted water quality standards, it is permitted.
In my opinion such a view runs counter both to the history and text of the Act, and in particular to the language of Section 301(a) of the Act, 33 U.S.C. § 1311(a), which in a straightforward manner states:
Except as in compliance with this section and sections 302, 306, 307, 318, 402, and 404 of this Act [33 U.S.C. §§ 1312, 1316, 1317, 1328, 1342, 1344], the discharge of any pollutant by any person shall be unlawful.
The use of flow augmentation is not authorized by any of the exceptions referred to in Section 301(a) of the Act.
As pointed out in the majority opinion, Michigan adopted its water quality standards effective December 12, 1973. Because the Administrator did not express his disapproval, they became standards under the FWPCA. Section 303(c)(3) of the Act, 33 U.S.C. § 1313(c)(3). Michigan’s adopted water quality standards do not provide for flow augmentation even by inference. The EPA was not accorded the opportunity to pass upon the question of flow augmentation when the standards were submitted to it, there being no suggestion that the issue was ever raised.
Ford’s Monroe plant is currently subject to a permit which does not include any authorization for the use of flow augmentation as a means of meeting the applicable water quality standards. The NPDES permit issued to Ford for its Monroe plant on December 20, 1974 was not vetoed by the EPA. Only six months later, however, a modification was sent to the EPA, proposr ing the use of flow augmentation by Ford to meet the water quality standards for the Raisin River. The modification sought would allow Ford to draw water from nearby Lake Erie, thus raising the flow of the Raisin River at the point of discharge. The proposal would permit Ford to divert any volume of water in order to meet the concentration limits contained in the water quality standards.1
Taking advantage of the fact that the Michigan water quality standards are stated on a per liter basis, Ford proposes a permit modification which would allow it to dilute its pollution to achieve the water quality standards without a reduction in the amount of pollutants it discharges. With the modification Ford proposes to dump more than twice as much metallic sludge into the Raisin River as has previously been permitted.
It is true that if Michigan water quality standards do not condone, neither do they expressly condemn flow augmentation as a means of achieving acceptable concentrations of discharged pollutants. And it is *673true that the Administrator’s power to veto under the Act may be exercised only when a permit is “outside the guidelines and requirements” of the Act, Section 402(d)(2) of the Act, 33 U.S.C. § 1342(d)(2). On this basis the majority holds that because it is unable to find any guidelines and requirements in the FWPCA or regulations promulgated under it upon which the EPA could rely to sustain its January 22, 1976 veto of the NPDES permit modification, the action was arbitrary and an abuse of discretion.2 It is this point at which I depart from the majority. In my view it is precisely because flow augmentation is not specifically approved as a means of achieving acceptable concentrations under Michigan’s water quality standards that the EPA is justified in intervening. Further, I am unwilling to compel that agency to promulgate regulations respecting flow augmentation as a condition to exercising its veto powers upon the facts here.
To be lawful under Section 301(a) of the Act, 33 U.S.C. § 1311(a), a discharge must satisfy carefully delineated exceptions set forth in the other sections of the Act. In other words, unless a discharge of pollutants can be shown to be legal, it is illegal under Section 301(a).3
The effect of the majority opinion is to require the EPA to point to a regulation which outlaws the flow augmentation technique before it can act. No doubt the potential means of evading the operation of the Act are myriad if the plain command of Section 301 is to be ignored. It was, in my judgment, precisely because such loopholes could not be anticipated that Congress couched the Act in such bold, prohibitory terms.4
While it is not necessary to hold that flow augmentation is implicitly forbidden by the FWPCA, there is much within the Act and its history to support such a view. Congress chose the phrase “effluent limitation ” to describe the means for attaining water quality. Section 302 of the Act, 33 U.S.C. § 1312.5 As we noted in Big Rivers Electric Corp. v. EPA, 523 F.2d 16 (6th Cir. 1975), cert, denied, 425 U.S. 934, 96 S.Ct. 1663, 48 L.Ed.2d 175 (1976), the concept “emission limitation” in. the Clean Air Act requires regulation of “the amount of [a pollutant] which may be included in the emission from a given source.” Id. at 22 (emphasis in original). A consistent construction of “effluent limitation” in the FWPCA suggests a similar intent on the part of Congress to achieve water quality by controlling quantity. Indeed, the definition of “effluent limitation” in the FWPCA denotes a concern for restricting the amount of pollutants:
The term “effluent limitation” means 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
Section 502(11) of the Act, 33 U.S.C. § 1362(11); See American Iron & Steel Institute v. EPA, 543 F.2d 521, 528 (3d Cir. 1976).
Such a view is fully substantiated in the legislative history. The goals and policy of *674Congress, as declared in the statute itself, include the prevention, reduction and elimination of pollutants from the nation’s water. Section 101(b) of the Act, 33 U.S.C. § 1251(b). The statute, needless to say, does not speak in terms of dilution. It is significant, however, that the Conference Committee replaced the words “abate” and “abatement” with “reduction” and “elimination” in Sections 101 and 102, 33 U.S.C. §§ 1251, 1252. S.Conf.Rep. 92-1236, 92nd Cong., 2d Sess. (1972), reprinted in 2 U.S. Code Cong. & Admin.News at 3778 (1972). Flow augmentation, it is agreed, simply reduces the concentration of pollutants introduced into a body of water. It does not, however, eliminate or reduce the quantity of the pollution.
A further indication of national policy is to be gleaned from Section 102(b)(1) of the Act, 33 U.S.C. § 1252(b)(1), which states:
In the survey or planning of any reservoir by the Corps of Engineers, Bureau of Reclamation, or other Federal agency, consideration shall be given to inclusion of storage for regulation of streamflow, except that any such storage and water releases shall not be provided as a substitute for adequate treatment or other methods of controlling waste at the source, (emphasis added).
The flow augmentation contemplated by Section 102(b)(1) involves the release of impounded waters at a time of low flow. The Act notes that such augmentation shall not be a substitute for “adequate treatment or other methods of controlling waste at the source.”6
The Conference Committee Report noted with respect to Section 102(b)(1):
The Conference substitute specifically bans pollution dilution as an alternative to waste treatment. At the same time it recognizes that stream flow augmentation may be useful as a means of reducing the environmental impact of runoff from non-point sources. The Conference substitute also recognizes that stream flow augmentation may be useful for recreational, navigation, and other purposes. Finally, section 102(b) [33 U.S.C. § 1252(b)] specifically sets forth that any calculation for the need for and value of stream flow augmentation to reduce the impact of pollution must be determined by the Administrator of the Environmental Protection Agency.7 (emphasis added).
S.Conf.Rep.No. 92-1236, 92d Cong., 2d Sess. (1972), reprinted in 2 U.S.Code Cong. & Admin.News at 3778-79 (1972).
Without question, Ford’s Monroe plant is a “point source,” as defined in Section 502(14) of the Act, 33 U.S.C. § 1362(14), and is thus not within the qualified exception recognized in the Conference Committee Report. The conclusion is inescapable that the drafters of the FWPCA did not intend industrial dischargers of waste materials from point sources such as Ford’s Raisin River plant to achieve statutory compliance by using dilution as a substitute for waste treatment.
The EPA’s position also finds analogous support in our court's interpretation of the Clean Air Act. In Big Rivers, supra, the Administrator had disapproved the Kentucky state implementation plan submitted under the Clean Air Act. We upheld the Administrator’s view that the dispersal of airborne contaminants was not a satisfacto*675ry means of achieving emission limitations, expressly approving similar reasoning in Natural Resources Defense Council, Inc. v. EPA, 489 F.2d 390 (5th Cir. 1974), rev’d in part on other grounds sub nom. Train v. Natural Resources Defense Council, Inc., 421 U.S. 60, 95 S.Ct. 1470, 43 L.Ed.2d 731 (1975). See 523 F.2d at 20-22. In NRDC v. EPA, the Fifth Circuit determined that the use of tall smokestacks merely achieved a dispersion of pollutants and did not limit the quantities emitted. The “tall stacks” technique was judged to be an inadequate means of attaining national primary ambient air quality standards.8 Flow augmentation is analogous to the use of tall stacks in that it facilitates the dispersion of pollutants but does not reduce the quantity disseminated into the waters.9
Finally turning to the Michigan Water Quality Standards themselves, they provide that:
[t]he water quality standards prescribed by these rules for the various designated uses of the waters of the state apply to receiving waters .
Michigan Water Quality Standards, Michigan Admin.Code, Part 4, Rule 323.1090. “Receiving waters” is defined therein as “the waters of the state into which an effluent is or may be discharged.” Id., Rule 323.1044(f). A natural construction of the terms “receiving waters” and “the waters of the state,” would not normally be thought to include waters which the polluter has artificially diverted from elsewhere into the stream in order to dilute the pollution. The concentrations expressed in the water quality standards applicable to the receiving waters of the Raisin River appear wholly consistent with the Administrator’s position and are inconsistent with the manipulation of flow contemplated by Ford.
Further, I cannot agree with the majority that we should take so grudging a view of the EPA’s articulated basis for the exercise of its veto. It is true, as the majority notes, that it is not for the courts to provide post hoc rationalization for an agency’s action which that agency has not itself given. It is also, however, true that our scope of review is a narrow one and that an agency decision of less than ideal clarity will be upheld “if the agency’s path may reasonably be discerned.” Bowman Transportation, Inc. v. Arkansas-Best Freight System, 419 U.S. 281, 286, 95 S.Ct. 438, 442, 42 L.Ed.2d 447 (1974), quoting Colorado Interstate Gas Co. v. FPC, 324 U.S. 521, 589, 65 S.Ct. 829, 89 L.Ed. 1206 (1945). The majority opinion would appear to confine the EPA to the grounds asserted in its letter of January 22, 1976, vetoing the permit modification. However, accompanying that letter was a memorandum dated January 14,1976, which the veto letter incorporated by reference. The January 22 letter stated:
Flow augmentation is not consistent with the requirements of the in-stream concentration limits contained in water quality standards.
The January 14 memorandum added:
In the instant case, the upstream concentration of pollutants expressed as pounds based on total river flow plus the BPT [best practicable technology] allowance of pounds of pollutants discharged after dilution exceed the in-stream concentration limitations. We, therefore, do not see flow augmentation as being consistent with the requirements of the in-stream concentration limits contained in the *676water quality standards, (emphasis in original).
The only reasonable construction of the January 14 and January 22 memoranda in the context of the EPA’s veto of the proposed permit modification is that simply satisfying the best practicable technology requirement contained in effluent limitation standards would be insufficient if in-stream concentration limits, without flow augmentation, still could not be met.10 This is exactly the situation contemplated by the Supreme Court in EPA v. State Water Resources Control Board, 426 U.S. 200, 205 n. 12, 96 S.Ct. 2022, 48 L.Ed.2d 578 (1976). The EPA thus expressed with clarity its view that the flow augmentation was not permitted by the water quality standards, which rest on in-stream concentrations of pollutants. It therefore concluded that no authority could be found in the Michigan water quality standards for enhancing the flow of a watercourse to achieve lawful pollutant concentrations. Because the water quality standards thus do not immunize the otherwise-unlawful discharge, Section 301(a) of the Act, 33 U.S.C. § 1311(a), applies to forbid the discharge.
Contrary to the view of the majority, I would hold that the path of the agency’s reasoning is sufficiently clear from its veto correspondence and does not constitute a post hoc rationalization.
Finally, I am unable to join in attributing a legal distinction to permits of “major” and minor significance. The majority apparently concludes that the Administrator’s veto will be summarily set aside if the permit is not of major significance — a conclusion which I am unable to draw from the authorities cited.11
Congress undoubtedly intended that, where states qualified themselves to issue NPDES permits, the great bulk of the work was to be performed by the state and that, to this extent, the EPA would be relieved of a great deal of responsibility which would otherwise be vested solely in it. This, however, is a far cry from holding that there is any statutory limitation upon the powers of the EPA under Section 402(d)(2) of the Act, 33 U.S.C. § 1342(d)(2). As the Second Circuit noted in Mianus River Preservation Committee v. Administrator, EPA, 541 F.2d 899, 907 (2d Cir. 1976):
Just how active a role the Administrator was expected to play in reviewing each particular State permit application is unclear from the statute itself. Section 402(d)(2) [33 U.S.C. § 1342(d)(2)], of course, gives the Administrator the power to review and reject any particular individual application for a State permit. Yet seemingly in the same breath, § 402(d)(3) [33 U.S.C. § 1342(d)(3)]12 relieves him of any duty to do either. The review power, as taken from the words of the statute, seems to be entirely discretionary. The legislative history of § 402 confirms that view and further shows that Congress intended that the Administrator should, more often than not, take no “action” with respect to proposed State permits.
I would hold, with the Second Circuit, that the review power under the Act is entirely discretionary with the EPA and is not limited to permits of major significance. The key to the system of review devised by Congress is a practical flexibility, with the EPA itself judging when the circumstances warrant its intervention. I would hold instead that any unlawful permit outside the *677guidelines and requirements of the Act would be the appropriate subject for a veto in the discretion of the EPA, Appalachian Power Co. v. Train, 545 F.2d 1351, 1358 (4th Cir. 1976). Contrary to the majority, I do not understand Natural Resources Defense Council, Inc. v. Train, 166 U.S.App.D.C. 312, 329, 510 F.2d 692, 709 (1975), to establish a test of “major significance” for judging the Administrator’s authority in reviewing state-issued permits under Section 402(d)(2) of the Act, 33 U.S.C. § 1342(d)(2).
Had ■ the EPA approved water quality standards for the State of Michigan expressly providing for flow augmentation, there would be much more force to the claim that its veto was arbitrary and capricious. As the majority concedes, however, the standards are silent as to flow augmentation. It is not for us to speculate that the Administrator approved or would have approved the use of flow augmentation, when such an inference is obviously inconsistent with the objectives of the Act and results in a strained construction of the water quality standards themselves.
The Administrator, in vetoing the proposed permit modification, has expressed his view that flow augmentation is an impermissible means of attaining the concentrations of pollutants contained in the water quality standards of Michigan. As our court held in Big Rivers, supra, “interpretations of this complex statute [the Clean Air Act] by the agency charged with administering it are entitled to great deference.” 523 F.2d at 22. Similar deference should be given to the EPA’s interpretation of the FWPCA and of the state water quality standards, the text of which the agency itself reviewed and approved. American Iron & Steel Institute v. EPA, 543 F.2d 521, 526 (3d Cir. 1976). In my view the Administrator was justified in concluding that flow augmentation was not a permissible technique for achieving water quality standards, since no express authorization in the Act or regulations can be found to support it. I would deny the petition for review and affirm the action of the Administrator.
. Ford originally sought approval for flow augmentation in 1971, when it applied for a discharge permit under the Rivers and Harbors Act, 33 U.S.C. § 407, the predecessor of the NPDES, Section 402(a)(5) of the Act, 33 U.S.C. § 1342(a)(5). While Ford’s 1971 draft proposal projected its requirements at 137 million gal-Ions a day, the permit modification at issue here imposes no ceiling on the quantity of water Ford could divert from Lake Erie. The modification, if approved by Michigan, would thus allow Ford to exceed even its 1971 projection to meet the state’s water quality standards.
. A review of the record dispels the idea that the EPA’s action usurped Michigan’s role in the state-administered plan for issuing NPDES permits. This permit is the only one of 1,479 NPDES permits issued by the State of Michigan to be voted by the EPA as of December 31, 1976, indicating the agency’s restrained use of its statutory veto power. This is not, therefore, a case of bureaucratic caprice run riot.
. Obviously Section 301(a) of the Act, 33 U.S.C. § 1311(a), is a guideline and requirement of the Act which would validate the Administrator’s action in disapproving the permit modification. See American Iron & Steel Institute v. EPA, 526 F.2d 1027, 1039-40 (3rd Cir. 1975).
. The breadth of Section 301, of course, is altogether consistent with the national goal of the Act “ . . . that the discharge of pollutants into the navigable waters be eliminated by 1985.” Section 101(a)(1) of the Act, 33 U.S.C. § 1251(a)(1).
. In addition, the nationwide system of discharge permits, which governs Ford’s Monroe plant and thousands of other point sources, is formally entitled the National Pollution Discharge Elimination System. Section 402 of the Act, 33 U.S.C. § 1342 (emphasis added).
. The EPA takes the view that “adequate treatment” means the best available technology (BAT). Memorandum from EPA General Council to Regional Administrators and State NPDES Directors at 4 (November 8, 1976). See generally Section 301(b)(2) of the Act, 33 U.S.C. § 1311(b)(2).
. The Act authorizes the Administrator to determine the value of flow regulation to achieve water quality:
(2) The need for and the value of storage for regulation of streamflow (other than for water quality) including but not limited to navigation, salt water intrusion, recreation, esthetics, and fish and wildlife, shall be determined by the Corps of Engineers, Bureau of Reclamation, or other Federal agencies.
(3) The need for, the value of, and the impact of, storage for water quality control shall be determined by the Administrator
Section 102(b)(2), (3) of the Act, 33 U.S.C. § 1252(b)(2), (3).
. National primary ambient air quality standards resemble water quality standards under the FWPCA in that both depend upon the aggregate of pollution over a given area or in a given watercourse rather than the pollution derived from any single source, EPA v. State Water Resources Control Bd., 426 U.S. 200, 205 n. 12, 96 S.Ct. 2022, 48 L.Ed.2d 578 (1976) (water quality standards); Train v. NRDC, supra, 421 U.S. at 65, 78, 95 S.Ct. 1470 (national primary ambient air quality standards).
. Congress recently amended the Clean Air Act with respect to tall stacks and other dispersion techniques. Clean Air Act Amendments of 1977, Pub.L.No. 95-95, § 123, 91 Stat. 721 (1977). As the legislative history makes explicit, Congress intended to endorse and codify the view of Big Rivers and NRDC v. EPA that dispersion is an inadequate substitute for treatment. H.R.Rep.No. 95-294, 95th Cong., 1st Sess. 91-92, reprinted in U.S.Code Cong. & Admin.News at 2300 (1977).
. Under the FWPCA, discharge permits issued by the State of Michigan, pursuant to Section 402(b) of the Act, 33 U.S.C. § 1342(b), require the discharger to conform both to the effluent limitations promulgated by the EPA and the water quality standards adopted by the state. Section 402(b)(1)(A) of the Act, 33 U.S.C. . § 1342(b)(1)(A).
. The majority finds the proposed permit modification to be of major significance, apparently not because of its impact on the Raisin River or Lake Erie but because the permit raises an issue of major significance, the use of flow augmentation to achieve water quality standards.
. Section 402(d)(3) of the Act, 33 U.S.C. § 1342(d)(3), allows the Administrator to waive his power to veto a state-issued permit which is “outside the guidelines and requirements” of the Act.