HUGHES, C. J. On January 4, 1934, the Tennessee Valley Authority, an agency of the Federal Government, entered into a contract with the Alabama Power Company, providing (1) for the purchase by the Authority from the Power Company of certain transmission lines, sub-stations, and auxiliary properties for $1,000,000, (2) for the purchase by the Authority from the Power Company of certain real property for $150,000, (3) for an interchange of hydroelectric energy, and in addition for the sale by the Authority to the Power Company of its "surplus power," on stated terms, and (4) for mutual restrictions as to the areas to be served in the sale of power. The contract was amended and supplemented in minor particulars on February 13 and May 24, 1934.

The Alabama Power Company is a corporation organized under the laws of Alabama and is engaged in the generation of electric energy and its distribution generally throughout that State, its lines reaching 66 counties. The transmission lines to be purchased by the Authority extend from Wilson Dam, at the Muscle Shoals plant owned by the United States on the Tennessee River in northern Alabama, into seven counties in that State, within a radius of about 50 miles. These lines serve a population of approximately 190,000, including about lO, O00 individual customers, or about one-tenth of the total number served directly by the Power Company. The real property to be acquired by the Authority (apart from the transmission lines above mentioned and related properties) is adjacent to the area known as the "Joe Wheeler dam site," upon which the Authority is constructing the Wheeler Dam....

Plaintiffs are holders of preferred stock of the Alabama Power Company. Conceiving the contract with the Tennessee Valley Authority to be injurious to the corporate interests and also invalid, because beyond the constitutional power of the Federal Government, they submitted their protest to the board of directors of the Power Company and demanded that steps should be taken to have the contract annulled.... Going beyond that particular challenge, and setting for the pronouncements, policies and programs of the Authority, plaintiffs sought a decree restraining these activities as repugnant to the Constitution, and also asked a general declaratory decree with respect to the rights of the Authority in various relations.

The defendants, including the Authority and its directors, the Power Company and its mortgage trustee, and the municipalities wxthin the described area, filed answers and the case was heard upon evidence. The District Court made elaborate findings and entered a final decree annulling the contract of January 4, 1934, and enjoining the transfer of the transmission lines and auxiliary properties. The court also enjoined the defendant municipalities from making or performing any contracts with the Authority for the purchase of power, and from accepting or expending any funds received from the Authority or the Public Works Administration for the purpose of constructing a public distribu tion system to distribute power which the Authority supplied. The court gave no consideration to plaintiff's request for a general declaratory decree.

The Authority, its directors, and the city of Florence appealed from the decree and the case was severed as to the other defendants. Plaintiffs took a cross appeal.

The Circuit Court of Appeals limited its discussion to the precise issue with respect to the effect and validity of the contract of January 4, 1934. The District Court had found that the electric energy required for the territory served by the transmission lines to be purchased under that contract is available at Wilson Dam without the necessity for any interconnection with any other dam or power plant. The Circuit Court of Appeals accordingly considered the constitutional authority for the construction of Wilson Dam and for the disposition of the electric energy there created. In the view that the Wilson Dam had been constructed in the exercise of the war and commerce powers of the Congress and that the electric energy there available was the property of the United States and subject to its disposition, the Circuit Court of Appeals decided that the decree of the District Court was erroneous and should be reversed. The court also held that plaintiffs should take nothing by their cross appeal. 78 F. (2d) 578. On plaintiffs' application we granted writs of certiorari, 296 U. S.

First. The right of plaintiffs to bring this suit....

We think that plaintiffs have made a sufficient showing to entitle them to bring suit and that a constitutional question is properly presented and should be decided.

Second. The scope of the issue. We agree with the Circuit Court of Appeals that the question to be determined is limited to the validity of the contract of January 4, 1934. The pronouncements, policies and program of the Tennessee Valley Authority and its directors, their motives and desires, did not give rise to a justiciable controversy save as they bad fruition in action of a definite and concrete character constituting an actual at threatened interference with the rights of to persons complaining. The judicial power does not extend to the determination of abstact questions....

As it appears that the transmission lines in question run from the Wilson Dam and that the electric energy generated at that dam |s more than sufficient to supply all the re twiements of the contract, the questions that are properly before us relate to the construction authority for the construction of the Wilson Dam and for the disposition, as provided in the contract, of the electric energy there generated. -Thrd. Tile constitutional authority for the action of the Wilson Dam. The Congress may not, "under the pretext of executing its powers, pass laws for the accomplishment of objects not entrusted to the governments Chief Justice Marshall, in Mc CullochlocSv. Maryland; Linder v. United States, 268 U. S. 15 17. The Government's argument recognizes this essential limitation. The Govermnents contention is that the Wilson Dam was constructed, and the power plant connected with it was installed, in the exercise by the Congress of its war and comerece powers. that is, for the purposes of national defense and the improvement of navagation....

We man take judicial notice of the international situation at the time the Act of 1916 was passed. and it cannot be successfully disputed that the Wilson Dam and its auxiliary its, including the hydro-electric power plant, are, and were intended to be, adapted to the purposes of national defense. Whilethe District Court found that there is no intention to use the nitrate plants or the; hydro electric units installed at Wilson Dam for the production of war materials in time of peace the maintenance of said properties in operating condition and the assurance of an abundant supply of electric energy is the event of war, constitute national defense assets" This finding has ample support. '

The Act of 19i6 also had in view "improvements to navigation." Commerce includes navigation. " All America understands, and has uniformly understood," said Chief Justice Marshall in Gibbons v. Ogden, "the word 'commerce,' to comprehend navigation." The power to regulate interstate commerce embraces the power to keep the navigable rivers of the United States free from obstructions to navigation and to remove such obstructions when they exist. "For these purposes," said the Court in Gilman v. Philidelphia, 3 Wall. 713, 725, "Congress possesses all the powers which existed in the States before the adoption of the national Constitution, and which have always existed in the Parliament in England." . . .

The Tennessee River is a navigable stream, although there are obstructions at various points because of shoals, reefs and rapids. The improvement of navigation on this river has been a matter of national concern for over a century....

While, in its present condition, the Tennessee River is not adequately improved for commercial navigation, and traffic is small we are not at liberty to conclude either that the river is not susceptible of development as an important waterway, or that Congress has not undertaken that development, or that the construction of the Wilson Dam was not an appropriate means to accomplish a legitimate end. The Wilson Dam and its power plant must be taken to have been constructed in the exercise of the constitutional functions of the Federal Government.

Forth. The constitutional authority to dispose of electric energy generated at the Wilson Dam. The Government acquired full title to the dam site, with all riparian rights. The power of falling water was an inevitable incident of the construction of the dam. That water power came into the exclusive control of the Federal Government. The mechanical energy was convertible into electric energy and the water power, the right to convert it into electric energy, and the electric energy thus produced, constitute property belonging to the United States.

Authority to dispose of property constitutionally acquired by the United States is expressly granted to the Congress by section 3 of Article IV of the Constitution. This section provides:

"The Congress shall have Power to dispose of and make all needful Rules and Regulations respecting the Territory or other Property belonging to the United States; and nothing in this Constitution shall be so construed as to Prejudice any Claims of the United States, or of any particular State."

To the extent that the power of disposition is thus expressly conferred, it is manifest that the Tenth Amendment is not applicable. And the Ninth Amendment (which petitioners also invoke) in insuring the maintenance of the rights retained by the people does not withdraw the rights which are expressly granted to the Federal Government. The question is as to the scope of the grant and whether there are inherent limitations which render invalid the disposition of property with which we are now concerned.

The occasion for the grant was the obvious necessity of making provision for the government of the vast territory acquired by the United States. The power to govern and to dispose of that territory was deemed to be indispensable to the purposes of the cessions made by the States.... The grant was made in broad terms, and the power of regulation and disposition was not confined to territory, but extended to "other property belonging to the United States," so that the power may be applied, as Story says, "to the due regulation of all other personal and real property rightfully belonging to the United States." And so, he adds, "it has been constantly understood and acted upon."

This power of disposal was early construed to embrace leases, thus enabling the Government to derive profit through royalties.... The policy, early adopted and steadily pursued, of segregating mineral lands from other public lands and providing for leases, pointed to the recognition both of the full power of disposal and of the necessity of suitably adapting the methods of disposal to different torts of property....

But when Congress thus reserved mineral ands for special disposal, can it be doubted that Congress could have provided for mining directly by its own agents, instead of giving that right to lessees on the payment of royalties? Upon what ground could it be said that the Government could not mine its own gold, silver, coal, lead, or phosphates in the public domain, and dispose of them as property belonging to the United States? That it could dispose of its land but not of what the land contained? It would seem to be clear that under the same power of disposition which enabled the Government to lease and obtain profit from sales by its lessees, it could mine and obtain profit from its own sales.

The question is whether a more limited power of disposal should be applied to the water power, convertible into electric energy, and to the electric energy thus produced at the Wilson Dam constructed by the Government in the exercise of its constitutional functions. If so, it must be by reason either of (1) the nature of the particular property, or (2) the character of the "surplus" disposed of, or (3) the manner of disposition.

(1) That the water power and the electric energy generated at the dam are susceptible of disposition as property belonging to the United States is well established....

(2) The argument is stressed that, assuming that electric energy generated at the dam belongs to the United States, the Congress has authority to dispose of this energy only to the extent that it is a surplus necessarily created in the course of making munitions of war or operating the works for navigation purposes, that is, that the remainder of the available energy must be lost or go to waste. We find nothing in the Constitution which imposes such a limitation. It is not to be deduced from the mere fact that the electric energy is only potentially available until the generators are operated. The Government has no less right to the energy thus available by letting the water course over its turbines than it has to use the appropriate processes to reduce to possession other property within its control, as, for example, or which it may recover from a pool beneath its lands, and which is reduced to possession by boring oil wells and otherwise might escape its grasp. And it would hardly be contended that, when the Government reserves coal on its lands, it can mine the coal and dispose of it only for the purpose of heating public buildings or for other governmental operations. Or, if the Government owns a silver mine that it can obtain the silver onll for the purpose of storage or coinage. Or that when the Government extracts the oil has reserved, it has no constitutional power to sell it. Our decisions recognize no so restriction. The United States owns the coal or the silver, or the lead, or the oil, it obtains from its lands, and it lies in the discretion the Congress, acting in the public interest to determine of how much of the property it all dispose.

We think that the same principle is applicableble to electric energy. The argument fessed upon us leads to absurd consequences in the denial, despite the broad terms of a constitutional provision, of a power of disposal which the public interest may imerativels rewire. Suppose, for example, that in the erection of a dam for the improvement of navigation, it became necessary to destroy a dam and power plant which had previousloy been erected by a private corporation engaged in the generation and dispution of energy which supplied the needs neighboring communities and business ensprises. Would anyone say that, because the United States had built its own dam and in the exercise of its constitutional ions, and had complete ownership and domain over both, no power could be suppliedn to the communities and enterprises dependent on it, not because of any unwillingness of the Congress to supply it, or of any overriding governmental need, but because there was no constitutional authority to further supply? Or that, with abundant power available, which must otherwise be wasted, the supply to the communities and rises whose very life may be at stake be limited to the slender amount of us unavoidably involved in the operation the navigation works, because the Constitution does not permit any more energy to be generated and distributed? In the case of Green Bay Canal Company, where the government works supplanted those of the Canal Comany, the Court found no difficulty in sustaining the Govemment's authority to grant to Canal Company the water powers which l previously enjoyed, subject, of course, dominant control of the Government.

And in the case of United States v. Chandlerar Dunbar Company supra, the statutory provision to which the Court referred, was "that excel of water in the St. Marys River Sault Sainte Marie over and above the Runt now or hereafter required for the uses of navigation shall be leased for power purpose by the Secretary of War upon such inns and conditions as shall be best caleated in his judgment to insure the development thereof." It was to the leasing, under this provision, "of any excess of power over the needs of the Government" that the Court saw no valid objection....

(3) We come then to the question as to the validity of tb method whack had in adopted in disposing of the surplus energy generated at the Wilson Dam. The constitutional provision is silent as to the method of disposing of property belonging to the United States. That method, of course, must be an appropriate means of disposition according to the nature of the property, it must be one adopted in the public interest as distinguished from private or personal ends, and we may assume that it must be consistent with the foundation principles of our dual system of government and must not be contrived to govern the concerns reserved to the States. In this instance, the method of disposal embraces the sale of surplus energy by the Tennessee Valley Authority to the Alabama Power Company, the interchange of energy between the Authority and the Power Company, and the purchase by the Authority from the Power Company of certain transmission lines.

As to the mere sale of surplus energy, nothing need be added to what we have said as to the constitutional authority to dispose. The Government could lease or sell and fix the terms. Sales of surplus energy to the Power Company by the Authority continued a practice begun by the Government several years before. The contemplated interchange of energy is a form of disposition and presents no questions which are essentially different from those that are pertinent to sales.

The transmission lines which the Authority undertakes to purchase from the Power Company lead from the Wilson Dam to a large area within about fifty miles of the dam. These lines provide the means of distributing the electric energy, generated at the dam, to a large population. They furnish a method of reaching a market. The alternative method is to sell the surplus energy at the dam, and the market there appears to be limited to one purchaser, the Alabama Power Company, and its affiliated interests. We know of no constitutional ground upon which the Federal Government can be denied the right to seek a wider market. We suppose that in the early days of mining in the West, if the Government had undertaken to operate a silver mine on its domain, it could have acquired the mules or horses and equipment to carry its silver to market. And the transmission lines for electric energy are but a facility for conveying to market that particular sort of property, and the acquisition of these lines raises no different constitutional question, unless in some way there is an invasion of the rights reserved to the State or to the people. We find no basis for concluding that the limited undertaking with the Alabama Power Company amounts to such an invasion Certainly, the Alabama Power Company has no constitutional right to insist that it shall be the sole purchaser of the energy generated at the Wilson Dam; that the energy shall be sold to it or go to waste.

We limit our decision to the case before Us, as we have defined it. The argument is earnestly presented that the Government by virtue of its ownership of the dam and power plant could not establish a steel mill and make and sell steel products, or a factory to manufacture clothing or shoes for the public, and thus attempt to make its ownership of energy, generated at its dam, a means of carrying on competitive commercial enterprises and thus drawing to the Federal Government the conduct and management of business having no relation to the purposes for which the Federal Government was established. The picture is eloquently drawn but we deem it to be irrelevant to the issue here. The Government is not using the water power at the Wilson Dam to establish any industry or business. It is not using the energy generated at the dam to manufacture commodities of any sort for the public. The Government is disposing of the energy itself which simply is the mechanical energy, incidental to falling water at the dam, converted into the electric energy which is susceptible of transmission. The question here is simply as to the acquisition of the transmission lines as a facility for the disposal of that energy. And the Government rightly conceded at the bar, in substance, that it was without constitutional authority to acquire or dispose of such energy except as it comes into being in the operation of works constructed in the exercise of some power delegated to the United States. As we have said, these transmission lines lead directly from the dam, which has been lawfully constructed, and the question of the constitutional right of the Government to acquire or operate local or urban distribution systems is not involved. We express no opinion as to the validity of such an effort, as to the status of any other dam or power development in the Tennessee Valley, whether connected with or apart from the Wilson Dam, or as to the validity of the Tennessee Valley Authority Act or of the claims made in the pronouncements and program of the Authority apart from the questions we have discussed in relation to the particular provisions of the contract of January 4, 1934, affecting the Alabama Power Company.

The decree of the Circuit Court of AppeY is affirmed.

Brandise, J delivered a separate opion in which Justices Stone Roberts and Cardozoa concuredrred. McReynolds, J dissented.