Mr. Justice White
delivered the opinion of the Court.
Section 23 (b) 1 of the Federal Power Act2 requires any person desiring to construct a dam or other project on a nonnavigable stream, but one over which Congress has jurisdiction under its authority to regulate commerce, to file a declaration of intention with the Federal Power Commission. If the Commission finds that “the interests of interstate or foreign commerce would be affected by such proposed construction,” the declarant may not construct or operate the project without a license. The issue here is whether the construction of a pumped storage hydroelectric project generating energy for interstate transmission is one which would affect the “interests of interstate or foreign commerce” within the intendment of the- Act.
[92] I.
Respondent Union Electric Co. (Union), operating generating plants and an interconnected transmission and distribution system in Missouri, Illinois, and Iowa, filed a declaration of intention pursuant to § 23 (b) to construct a pumped storage hydroelectric facility, the Taum Sauk installation, as a part of Union’s interstate system. The pumped storage plant, an engineering innovation of growing use, is to supplement the energy produced by other plants during periods of peak demands. During such periods it generates energy through use of hydroelectric units driven by water falling from an elevated reservoir into a lower pool.3 During off-peak periods it uses energy from other sources to pump water from the lower pool back to the headwater pool.4 The project is capable [93] of creating up to 350 megawatts and the energy created will be utilized in Missouri, Illinois, and possibly Iowa. Taum Sauk is to be located on the East Fork of the Black River, about four miles above the confluence of these waters.5 The East Fork is a nonnavigable tributary of the Black River, itself a navigable stream along with the White River into which it flows.
The FPC found the East Fork was a stream “over which Congress has jurisdiction under its authority to regulate commerce,” since it is a headwater of a navigable river system. The project would affect the interests of commerce and would require a license, the FPC also held, both because it contemplated the utilization of water power for the interstate transmission of electricity and because it would affect downstream navigability, 27 F. P. C. 801. The Court of Appeals reversed, 326 F. 2d 535 (C. A. 8th Cir.) holding that the only “commerce” which is relevant to the FPC’s determination under § 23 (b) is commerce on the downstream navigable waterway and that the project in question would have no significant impact on water commerce.6 Absent an [94] effect on downstream navigability, or on irrigation development, flood control projects or planned utilization of water resources, matters which might affect the interests of water commerce, a water power project located on the headwaters of a navigable river is a “local” activity beyond the licensing power and consequent regulatory controls of the FPC. Because the question is an unresolved one of jurisdiction over an important class of hydroelectric projects, we granted certiorari, 379 U. S. 812, and now reverse the judgment of the Court of Appeals. We have determined that its limitation of the FPC’s licensing power to projects affecting commerce on navigable waters is founded upon an erroneous reading of the language of § 23 (b) and the design and purposes of the Federal Water Power Act.
II.
To focus the inquiry, it is well to state what is not involved in this case. There is no question that the interstate transmission of electric energy is fully subject to the commerce powers of Congress. Public Utilities Comm’n v. Attleboro Steam & Elec. Co., 273 U. S. 83, 86; Electric Bond & Share Co. v. Securities & Exchange Comm’n, 303 U. S. 419, 432-433. Nor is there any doubt today that projects generating energy for such transmission, such as Taum Sauk, affect commerce among the States and therefore are within the purview of the commerce power, quite without regard to the federal control of tributary streams and navigation. See Labor Board v. Jones & Laughlin Steel Corp., 301 U. S. 1, 40-41; Labor Board v. Fruehauf [95] Trailer Co., 301 U. S. 49; Consolidated Edison v. Labor Board, 305 U. S. 197; Katzenbach v. McClung, 379 U. S. 294, 301-304. But see United States v. Appalachian Power Co., 107 F. 2d 769, rev’d on other grounds, 311 U. S. 377.7 Thus, there are no constitutional doubts or barriers to the FPC’s interpretation. The only question is whether Congress has required a license for a water power project utilizing the headwaters of a navigable river to generate energy for an interstate power system. We think an affirmative answer is required by both the language and purposes of the Act.
The language of the Act, in our view, plainly requires a license in the circumstances of this case. Section 23 (b)8 [96] prohibits construction of nonlicensed hydroelectric projects on navigable streams, regardless of any effect, detrimental or beneficial, on navigation or commerce by water and requires those proposing a project on a nonnavigable stream to file a declaration of intention and to come before the Commission for a determination of whether the “interests of interstate or foreign commerce would be affected,” a determination which obviously does not speak in terms of the interests of navigation or water commerce. Plainly the provision does not require a license only where “the interests of interstate or foreign commerce on navigable waters would be affected.” Although transportation on interstate waterways is interstate commerce, the phrase “affect the interests of commerce” on its face hardly supports any claim that Congress sought to regulate only such transportation. Rather, it strongly implies that Congress drew upon its full authority under the Commerce Clause, including but not limited to its power over water commerce. “[H]alf a dozen enactments, other than the National Labor Relations Act, are sufficient to illustrate that when [Congress] wants to bring aspects of commerce within the full sweep of its constitutional authority, it manifests its purpose by regulating not only ‘commerce’ but also matters which ‘affect,’ ‘interrupt,’ or ‘promote’ interstate commerce. ... In so describing the range of its control, Congress is not indulging stylistic preferences.” Polish National Alliance v. Labor Board, 322 U. S. 643, 647.
The scope of this language is not restricted by the earlier clause in § 23 (b) limiting the filing requirements [97] to projects on nonnavigable streams “over which Congress has jurisdiction under its authority to regulate commerce” that is, tributaries of river systems necessitating supervisory power to preserve or improve downstream navigability or water commerce generally. See United States v. Rio Grande Dam & Irrigation Co., 174 U. S. 690; Phillips v. Guy F. Atkinson Co., 313 U. S. 508. This language merely designates those who must file a declaration of intention- — all those who would locate a water power project on a nonnavigable stream within the jurisdiction of Congress are required to declare their intention so that the Commission may determine the necessity for a license. Congress then proceeds to invoke its full authority over commerce, without qualification, to define what projects on nonnavigable streams are required to be licensed. Respondent asserts that commerce must mean the same thing in both the filing and licensing requirements of § 23 (b); because of the allusion to water commerce in the filing provision, the Commission’s inquiry into the effect of the project on commerce must be limited to the source of Congress’ power over the stream. Nothing in the structure or syntax of § 23 (b) compels this conclusion. Indeed, in describing in distinct terms the standard for who must file and what must be licensed,9 the more compelling inference is that Congress in[98] tended the inquiry into the project’s effect on commerce to include, but not be limited to, effect on downstream navigability.10
Turning to the purposes of the Federal Water Power Act, enacted in 1920, we find nothing which casts serious doubt upon our reading of § 23 (b) or which indicates that the Commission was to restrict its considerations under § 23 (b) to effect on navigability. There is much to indicate the contrary.
The central purpose of the Federal Water Power Act was to provide for the comprehensive control over those uses of the Nation’s water resources in which the Federal Government had a legitimate interest; these uses included navigation, irrigation, flood control, and, very prominently, hydroelectric power — uses which, while unregulated, might well be contradictory rather than harmonious.11 Prior legislation in 1890 and the Rivers and Har[99] bors Act of 1899,12 prohibiting the erection of any obstruction to navigation, including those on nonnavigable feeders, United States v. Rio Grande Dam & Irrigation Co., 174 U. S. 690, and requiring the consent of Congress and approval of the Secretary of War before constructing a bridge, dam, or dike along or in navigable waters, was thought inadequate, for it accommodated only the federal interest in navigation. As this Court has had occasion to note before, the 1920 Federal Water Power Act “was the outgrowth of a widely supported effort of the conservationists to secure enactment of a complete scheme of national regulation which would promote the comprehensive development of the water resources of the Nation, in so far as it was within the reach of the federal power to do so . . . .” First Iowa Hydro-Electric Coop. v. Federal Power Comm’n, 328 U. S. 152, 180. The principal use to be developed and regulated in the Act, as its title indicates, was that of hydroelectric power to meet the needs of an expanding economy.13
[100] The provisions of the Act reflect these objectives. The preface states that besides navigation and the creation of the Commission, the Act was “to provide for the . . . development of water power; the use of the public lands in relation thereto . . . and for other purposes.” 41 Stat. 1063. Section 10 (a), as amended, requires as a condition for obtaining a license that the proposed project “be such as in the judgment of the Commission will be best adapted to a comprehensive plan for improving or developing a waterway or waterways for the use or benefit of interstate or foreign commerce, for the improvement and utilization of water-power development, and for other beneficial public uses . . . .”14 Other provisions regulate the operations, services, charges, and duration of hydroelectric plants,15 “provisions . . . not essential to or [101] even concerned with navigation as. such,” but which “have an obvious relationship to the exercise of the commerce power.” United States v. Appalachian Power Co., 311 U. S. 377, 424, 427. In order to insure comprehensive control over the utilization of the Nation's waterways, “navigable stream” was broadly defined to include the interrupting falls, shallows, rapids and the waterways authorized by or recommended to Congress for improvement; 16 and other recognized sources of federal authority were invoked, such as jurisdiction over public lands and national forests.17
If the comprehensive development of water power, “in so far as it was within the reach of the federal power to do so,” First Iowa Hydro-Electric Coop. v. Federal Power Comm’n, 328 U. S., at 180, was the central thrust of the Act, there is obviously little merit to the argument that § 23 (b) requires a license when the interests of water commerce are affected but dispenses with the license when other commerce interests are vitally involved. The purposes of the Act are more fully served if the Commission must, as it held in this case, consider the impact of the project on the full spectrum of commerce interests.
III.
Union’s earnest position, however, is that the legislative history of the Act reveals a more limited purpose and requires a narrower construction of § 23 (b). The core of the argument is that the constitutional basis for the Act generally and for § 23 (b) in particular was the [102] authority of Congress over navigation, that Congress invoked only this power, and no other, and that § 23 (b) accordingly provides for no greater control over projects on nonnavigable streams than is necessary to protect downstream navigability. On these matters, it is said, both conservationists and opponents of the Act agreed. Moreover, the argument continues, the limited reach of § 23 (b) is confined by the repeated references to navigation and to congressional power over it in the course of committee hearings and reports on the 1935 amendments to the Act.
We cannot distill as much as Union does from the long and intense legislative struggle to enact what was a decided innovation in federal policy. The Act unquestionably involved an invocation of the congressional power over navigation under the Commerce Clause, since it required a license to build any water power project on a navigable stream, broadly defined,18 regardless of any actual effect on navigation. There was, consequently, considerable debate about the scope and extent of the federal power over river navigation, about the definition of “navigable waters” and about the authority of Congress to impose controls and conditions having little relevance [103] to the protection of navigation.19 Some thought the Commerce Clause did not extend to anything but the navigable mainstream itself, and then only for the purpose of preserving or improving water transportation. This broad objection to the Act found expression in remarks directed at § 23 (b) and in assertions that the power over navigation was not sufficient to require the licensing of projects on nonnavigable streams, save perhaps where downstream navigability was substantially affected.20 [104] Since the opponents of the Act mounted a major attack on the federal power over navigation, and this was a well-recognized basis of Commerce Clause authority, the proponents defended on this ground. Navigation and federal power over it hence permeated the debates, and statements reflecting the understandings and disagree-[105] merits over these issues understandably constitute a considerable part of the context in which the Act was enacted.
But none of this history can fairly be said to meet, much less determine, the question presented here. That question is not whether Congress exercised its authority over navigation in the Federal Water Power Act, which it most assuredly did, but whether in enacting § 23 (b) it also invoked its full Commerce Clause authority over hydroelectric projects located on waters subject to federal jurisdiction. The fact that there were debates over the extent of federal power over navigation, or over navigable or nonnavigable streams, sheds little light on whether Congress did, or did not, intend to rely on other aspects of its power over commerce when it directed a Commission determination of the effects of a proposed project on the “interests of commerce.” It is true that the debates on § 23 (b), taking the course that they did, contain no express references to interstate commerce in electrical energy, perhaps because the authority to regulate the production of goods destined for interstate shipment was far less defined and understood at that time, see Hammer v. Dagenhart, 247 U. S. 251, decided in 1918, and perhaps because no one was inclined to inject other constitutional issues into the ongoing debates.21 But the [106] Act which emerged from these debates, and § 23 (b) in particular, was couched in terms which reached beyond the control of navigation and forms no support for the proposition that Congress intended to equate the “interests of commerce” with those of navigation.22
Indeed, this history indicates that Congress was differentiating between the two. The House version of § 23 (b) granted permission to construct a dam on a non-navigable stream and provided for a license if the Commission found the improvement justified for the purpose of improving or developing the waterway “for the use or benefit of navigation in interstate or foreign commerce.” 23 The Senate Committee, along with the expansion of the definition of navigable waters, amended this to require the Commission to make an immediate investigation and to prohibit the construction without a license if the Commission found that “the interests of interstate or foreign commerce would be affected.” 24 Only if the Commission did not so find was the declarant granted permission to construct upon compliance with state laws. No one offered any explanation for the substitution of the inclusive term “affect the interests of interstate commerce.” 25 [107] But conservationists and opponents seemed to agree that the Act embodied the full measure of Congress’ authority-under the Commerce Clause to regulate hydroelectric projects.26 And there is no evidence that the sponsors of the Act, who prevailed in securing its enactment in the broad terms they drafted; intended a construction of interstate or foreign commerce narrower than their constitutional counterparts. In the face of numerous objections to this exercise of federal authority, we find it of compelling significance that the Congress adopted comprehensive language and refrained from writing any limitation or reference to navigation into § 23 (b).
The materials concerning the 1935 amendments do not alter our conclusion. Here the hearings and reports contained references to navigation and to the federal authority over navigable and nonnavigable streams.27 The House Report, for example, stated that “every person intending to construct a project which might affect navigation would be required to come to the Commission for a determination of the interests of the United States.” H. R. Rep. No. 1318, 74th Cong., 1st Sess., 26. To the same effect, see S. Rep. No. 621, 74th Cong., 1st Sess., [108]*10846-47. Such statements clearly refer to the filing requirement of § 23 (b), which was the subject of the committee amendment. Only persons constructing projects on nonnavigable feeders of navigable waters need file a declaration of intention. The committee statements are thus quite accurate in this respect, but they do not illuminate the licensing provision of § 23 (b), as distinct from its filing requirement, nor do they resolve the issue of which projects among those which might affect navigation are required to be licensed. They do not, explicitly or implicitly, exempt from licensing those projects having no effect on navigation. The reports do not equate the “interests of commerce” with those of water transportation.
It is true that there are no express references in the reports or the debates to other aspects of the commerce power in connection with § 23 (b), but the reports reflect the same broad intent as the earlier deliberations to secure federal control over all water power projects involving the utilization of the Nation’s river systems.
“The act would be greatly strengthened by enabling the Commission to preserve control over all projects with which the Federal Government has any valid concern.” S. Rep. No. 621, 74th Cong., 1st Sess., 47.
See also H. R. Rep. No. 1318, 74th Cong., 1st Sess., 26. And on the floor of Congress objections to federal control over projects on nonnavigable streams, similar to those voiced in 1920, were again rejected as inconsistent with effective water power regulation. 79 Cong. Rec. 10568. Moreover, there was promptly eliminated an amendment to § 23 which would have required a license only when the “interests of interstate or foreign commerce would be directly affected or burdened by such proposed construction.” 28
[109] Nor can we ignore the actual effect of the filing requirement added in 1935. The applicable provision prior to this amendment, § 9 of the Rivers and Harbors Act, 30 Stat. 1151, forbidding obstructions to navigation, was adequate to insure that projects with a substantial effect on downstream navigability would be brought before the Commission. Persons intending to construct a project which would likely have no such effect, such as some pure pumped storage installations, could decline to file a declaration of intention with impunity. Thus the 1935 amendment made a difference principally in regard to projects which predictably have little, if any, effect on navigation but a significant effect on interstate commerce. Respondent would have us assume this difference was not intended, although both the Committees stated that the amendment would enable “the Commission to preserve control over all projects with which the Federal Government has any valid concern.” S. Rep. No. 621, 74th Cong., 1st Sess., 47; H. R. Rep. No. 1318, 74th Cong., 1st Sess., 26. In light of the necessary purport of this amendment and the breadth of the federal interest in hydroelectric projects expressed in the 1920 Act, the preoccupation of the Commission and the committees with navigation, while not without significance, does not overcome the clear import of the language and the purposes of the Act.
The respondent asserts that an anomalous consequence flows from the Commission’s construction of the Act and its view that steam plants generating large amounts of energy for interstate transmission are not within the scope of § 23 (b), although located along a stream over which Congress has jurisdiction. Since the Commission’s jurisdiction here rests solely on the interstate transmission of energy, there can be no basis for distinguishing [110] between a steam plant and a hydroelectric facility both generating energy for interstate use. The Court of Appeals, after noting that the generation of electric energy is a local or intrastate activity, concluded from this argument that “[t]he Commission’s jurisdiction . . . must logically rest upon its delegated congressional jurisdiction over the interests of commerce on navigable waters.” 326 F. 2d, at 551. On this reasoning either the Act should, but does not, require a license for a steam plant when situated on the navigable mainstream itself, or should not, but does, require a license for a hydroelectric plant, pumped storage or otherwise, situated on the mainstream, but which has no demonstrable effect, or a beneficial effect, on navigability. The answer to this conundrum is that unlike Part II of Title II of the Public Utility Act of 1935, under which the Commission regulates various aspects of the sale and transmission of energy in interstate commerce, Part I, the original Federal Water Power Act, is concerned with the utilization of water resources and particularly the power potential in water. In relation to this central concern of the Act,29 the distinction between a hydroelectric project and a steam plant is obvious, and meaningful, although both produce energy for interstate transmission.30
Reversed.
“It shall be unlawful for any person ... for the purpose of developing electric power, to construct, operate, or maintain any dam, water conduit, reservoir, power house, or other works incidental thereto across, along, or in any of the navigable waters of the United States, or upon any part of the public lands or reservations of the United States (including the Territories), or utilize the surplus water or water power from any Government dam, except under and in accordance with ... a license granted pursuant to this Act. Any person ... intending to construct a dam or other project works across, along, over, or in any stream or part thereof, other than those defined herein as navigable waters, and over which Congress has jurisdiction under its authority to regulate commerce with foreign nations and among the several States shall before such construction file declaration of such intention with the Commission, whereupon the Commission shall cause immediate investigation of such proposed construction to be made, and if upon investigation it shall find that the interests of interstate or foreign commerce would be affected by such proposed [96] construction, such person . . . shall not construct, maintain, or operate such dam or other project works until it shall have applied for and shall have received a license under the provisions of this Act. If the Commission shall not so find, and if no public lands or reservations are affected, permission is hereby granted to construct such dam or other project works in such stream upon compliance with State laws.”
The movement toward the enactment of the Act in 1920 may be said to have taken its keynote from President Roosevelt’s veto of a bill which would have turned over to private interests important power sites on the Rainy River. He said:
“We are now at the beginning of great development in water power. Its use through electrical transmission is entering more and more largely into every element of the daily life of the people. Already [99] the evils of monopoly are becoming manifest; already the experience of the past shows the necessity of caution in making unrestricted grants of this great power.
“It should also be the duty of some designated official to see to it that in approving the plans the maximum development of the navigation and power is assured, or at least that in making the plans these may not be so developed as ultimately to interfere with the better utilization of the water or complete development of the power.” 42 Cong. Rec. 4698.
The history of the movement and its objectives are well recounted in Kerwin, Federal Water-Power Legislation 105-293 (hereafter Kerwin); Pinchot, The Long Struggle for Effective Federal Water Power Legislation, 14 Geo. Wash. L. Rev. 9 (1945).
“Stripped of its covering, the proposal relates not to commerce between the States or with foreign nations, but it authorizes a commission to issue licenses to corporations and to individuals to build dams and to erect power houses for the generation of electricity for industrial purposes. And in this purpose may be found the explanation of the strained effort to enlarge the definition of 'navigable waters’ beyond its proper limits. The proponents of this legislation are not concerned with navigation and so with navigable waters in fact. Theirs is a scheme of power development for the demands and the profits of industry under Federal control. They recognize the impracticability of such developments upon streams navigable in fact and in law, except under unusual and exceptional conditions. . . . Limit this definition of 'navigable waters’ as we may and the bill even then will go to the very verge of constitutional inhibition. I know of no authority in our fundamental law for the licensing by Congress of corporations and individuals for the building of dams, the erection of power houses, and the generation of electricity for industrial and commercial purposes. There are those who profess to believe that this may be done upon navigable streams as an incident to the improvement of navigation. Whether this view be sound or not, it is clear in my mind that such powers can not be exercised by [104] the Federal Government within the limits of our States upon streams which are not navigable and over which Congress has no jurisdiction. . . .” 59 Cong. Rec. 6531 (remarks of Representative White).
“As a matter of law, aside from purposes of navigation, the use of the water in the different streams of the several States belongs to the people of those States and not to the Federal Government. The argument insisted upon amounts to this: That the Federal Government is to sell and to make a charge for water that does not belong to it, but which belongs to the people of the States.” 59 Cong. Rec. 1430 (remarks of Senator Nelson).
“Mr. KING. Obviously, then, under the Senator’s contention, the Federal Government would have jurisdiction over the snow line, and, ns the Senator from Colorado [Mr. Thomas] sotto voce says, it would have jurisdiction of the clouds which produce the snow which melts and produces the spring which produces the tributary flowing into the river which is navigable. So that the Federal Government may stretch out its powerful and omnipotent hand until it can grasp the snow in the mountains and say, ‘We have jurisdiction over that.’
“Mr. NELSON. That is a forced construction.
"Mr. KING. I think that the Senator’s position leads to that.
“Mr. NELSON. It does not lead to that, and that is not my position. The Senator a few moments ago referred to the Rio Grande case. The court intimated incidentally in that opinion that the control of Congress extended to the feeders of the stream, but when it comes to applying the principles of law to the facts in each case they must be measured by the facts. The court did not mean to decide that the feeders were navigable. What the court meant to say was that the Federal Government has sufficient jurisdiction'over the feeders to see to it that the supply of water shall not be destroyed or so diminished in the feeders as to prevent the main stream from being navigable. . . .
"... Does the diversion of the water of a certain feeder of a certain stream for irrigation purposes diminish the quantity of the water to such an extent as to destroy the navigability of the main stream? If the diversion of the water did not diminish the navigability of the [105] main stream, the Government would have no control whatever. Furthermore, it would only have control to the extent of the supply of water needed to subserve the purposes of real navigation.
“We are not seeking to interfere with the present situation, and no matter what we put into this bill, if the Senator from Maine will excuse me a moment longer, we can not change the decisions of the Supreme Court as to their determination of the words ‘navigable stream.’ We could not undo by this legislation, if we should make the effort, what they have decided. Wo have made no such attempt.” 59 Cong. Rec. 7730.
See also 59 Cong. Rec. 1041-1042, 1472, 7723-7730. Cf. 57 Cong. Rec. 4636-4638, 56 Cong. Rec. 9038.
It is true that the FPC has not previously required a license for hydroelectric projects generating for interstate markets, but having no effect on navigability, but the existence of such projects in any number may be doubted. The construction of pure pumped storage installations on small streams is a relatively recent development. Thus pure pumped storage projects were not of significance to the federal interest in hydroelectric plants in the early days of the Act.
Further, the FPC’s view here is not novel. A Court of Appeals expressly dealt with and rejected this construction of the Act in 1939, United States v. Appalachian Power Co., 107 F. 2d 769, 793 (C. A. 4th Cir.). There the Court of Appeals held, in a decision relied on by the court below, that the Commission’s construction was untenable “either on the basis of statutory construction or constitutional authority,” resting this conclusion in part on a very narrow view of Congress’ authority under the Commerce Clause over hydroelectric projects, whether on navigable or nonnavigable waters. This Court, although finding the stream in question navigable, rejected this underpinning of the Court of Appeals’ decision and made quite explicit the broad nature of the federal interest in hydroelectric projects. The Court also expressly put aside the issues posed by the intended interstate sales. 311 U. S. 377. Thus the issue herein presented can fairly be said to have been unsettled and unresolved since that decision, as evidenced by an examiner’s ruling in 1954 that a project required a license because it would generate energy for interstate transmission. The Commission followed the earlier Court of Appeals’ decision and rejected this ruling in a cursory dictum, the project requiring a license on the more traditional ground of effect on navigability. California Oregon Power Co., 13 F. P. C. 1, 3.
The FPC itself has regarded the question as an open one, stating, in reaching the issue in this ease, that “an issue of such importance must not be allowed to go unresolved any longer since there can be little doubt that this country in the years ahead will become over[112] whelmingly more dependent upon the maximum development of its water resources in all their uses.” 27 F. P. C. 801, 806-807.
We do not find in these circumstances a generally acknowledged jurisdictional limitation or a consistently held administrative interpretation. See American Trucking Assns. v. United States, 344 U. S. 298.