of the public domain are involved, and the interest of the United States depends entirely on the Commerce Clause of the Constitution and the right thereunder to prevent obstruction to or to improve navigable highways of interstate or foreign commerce. This project (No. 389) first came before the Federal Power Commission on February 10, 1923, when there was filed with the Commission a declaration of intention to construct the dam. The proceedings before the Commission were pursuant to that part of section 23 of the Federal Water Power Act which is as follows:

"That any person, association, corporation, State, or municipality 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 between foreign nations and among the several States, may in their discretion 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 construction, such person, association, corporation, State, or municipality shall not proceed with such construction 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." (41 Stat. 1075.)

On February 13, 1923, the declarants were advised that the Cumberland River was navigable and that they should file application for a preliminary permit. This was filed on March 8, 1923, and a preliminary permit was granted on March 24, 1924. On March 17, 1926, application for a license was filed, and is still pending. On June 14, 1929 (see Ninth Annual Report, pp. 101-102), the Commission found that the Cumberland River at the point involved in the project affecting Cumberland Falls is not navigable waters but that the navigability of navigable sections of the

river, and consequently the interests of interstate and foreign commerce, would be affected by the proposed construction. This finding was based on the following statement of facts (Ninth Annual Report, p. 102):

"The application for license contemplates a dam 80 feet high to create a reservoir with a capacity of about 46,000 acre-feet, a diversion tunnel, and a power house with initial and ultimate installation capacities of 40,000 horsepower and 80,000 horsepower, respectively. The capacity of the proposed reservoir is sufficient to retain the entire monthly flows of 20 out of the 108 months which comprise the period from 1918 to 1927. The plant, if operated to supply peak loads during the low-water stages of the river, would have capacity to produce such waves in the river at the gaging station near Burnside as would vary the navigable depth approximately 2 feet for the initial installation and 4 feet for the ultimate installation. The variation in navigable depths at Nashville under similar conditions of operation would be three-fourths to 114 feet. The variations in the navigable depths reaching a magnitude of 2 feet in a 6-foot project would, if not appropriately regulated, materially interfere with navigation in the channels so affected. It is concluded, therefore, that the section of Cumberland River involved does not constitute navigable waters within the definition of the Federal Water Power Act, but that the proposed project would affect the navigable capacity of the navigable sections of the river and, consequently, the interests of interstate or foreign commerce." (Italics ours.)

I

The first question submitted is whether the Commission has jurisdiction to entertain on its merits the application for license for this dam on upper nonnavigable reaches of the Cumberland River.

Section 10 of the Act of March 3, 1899 (c. 425, 30 Stat. 1121, 1151), which is still in force, is as follows:

"SEC. 10. That the creation of any obstruction not affirmatively authorized by Congress, to the navigable capacity of any of the waters of the United States is hereby prohibited; and it shall not be lawful to build or com

mence the building of any wharf, pier, dolphin, boom, weir, breakwater, bulkhead, jetty, or other structures in any port, roadstead, haven, harbor, canal, navigable river, or other water of the United States, outside established harbor lines, or where no harbor lines have been established, except on plans recommended by the Chief of Engineers and authorized by the Secretary of War; and it shall not be lawful to excavate or fill, or in any manner to alter or modify the course, location, condition, or capacity of, any port, roadstead, haven, harbor, canal, lake, harbor of refuge, or inclosure within the limits of any breakwater, or of the channel of any navigable water of the United States, unless the work has been recommended by the Chief of Engineers and authorized by the Secretary of War prior to beginning the same."

This statute applies to the construction of works upon a nonnavigable portion of a stream which would impair the navigable capacity of lower navigable portions thereof. In United States v. Rio Grande Dam and Irrigation Co., 174 U. S. 690, the United States succeeded in enjoining the construction of a dam on the nonnavigable portions of the Rio Grande River, the effect of which would have been to impair the navigable capacity of the lower navigable portions of the river.

Under the provisions of Article I, section 8, clause 3, of the Constitution of the United States, which empowers Congress to regulate commerce with foreign nations and among the several States, Congress has power to control and protect navigation on streams suitable for interstate and foreign commerce, and in the exercise of that power it is settled, as in United States v. Rio Grande Dam and Irrigation Co., above cited, that Congress has the right to prevent or abate dams or other structures on the upper nonnavigable reaches of rivers the effect of which is to impair the navigable capacity of the lower navigable portions of the stream. It also has power to provide for the erection of dams in the upper nonnavigable portions of a stream for the purpose of improving navigation on lower reaches, when the navigable portions of the stream are available for interstate or foreign commerce.

merce.

It was because of these powers and what may be done under them that the above-quoted portion of section 23 of the Federal Water Power Act was enacted. Construction of a dam on the upper nonnavigable part of a stream which in its lower reaches is a highway of interstate commerce subjects the owner of the dam to the risk of being assailed on the ground that his dam has an injurious effect on comHis investment is subject to this hazard. The provisions in section 23 above quoted were intended, among other things, to enable those proposing to construct such a dam to obtain a ruling from an agency of the Federal Government in advance of construction as to whether the proposed structure would injure the navigable capacity of lower navigable portions of the stream. The statute does not require those proposing to erect such a dam to file application for license with the Federal Power Commission; if they choose to proceed without a license and take the risk of later proceedings by the Federal Government to enjoin the maintenance of their dam, they are at liberty to do so. The Act provides that any persons intending to build a dam "may in their discretion" proceed before the Commission. Where it is thus proposed to construct a dam across the nonnavigable portions of a stream, and a declaration of intention is filed, the Act contemplates that the Commission shall first determine whether the interests of interstate or foreign commerce would be affected by such proposed construction. This requires an inquiry by the Commission as to whether the waters of the stream in which the dam is to be erected flow into navigable waters on which interstate or foreign commerce is conducted, and if so, whether the construction of the dam would directly and substantially affect the navigable capacity of the lower navigable waters and thus affect the interests of interstate or foreign commerce. If it finds that such conditions exist, it is the duty of the Commission to entertain an application for a license and, if it appears that the proposed dam, if properly constructed and operated, would not substantially and directly injure navigation, to grant a license. Having power to prevent the erection in nonnavigable waters of any structure which would substantially impair the navigable capacity of the lower reaches of the stream, I see no reason to doubt that Congress has

power to establish a tribunal, as has been done by this Act, to make, in advance of construction, a finding or ruling at the request of those desiring to build such structures so that they may know in advance of construction whether they are likely to be interfered with by the Federal Government.

On the facts submitted, I am of the opinion that the Commission has jurisdiction to entertain the application of the Cumberland Hydro-Electric Power Company for a license to carry out its project on the Cumberland River.

II

The next question submitted is whether the navigable capacity of a given stream may be referred to and determined by the Attorney General upon a statement of the evidence, or whether it is a question of fact to be determined by the Federal Power Commission.

Whether a stream is navigable is a mixed question of law and fact. The first step is to determine what is the definition or test of navigability. The next step is to apply that test to the facts of the case. If there were any doubt as to the definition or test of navigability, it might be appropriate to submit to the Attorney General a request for an opinion on that point, but that is a matter long since settled by the courts. In United States v. Holt State Bank, 270 U. S. 49, 56, it was said:

"The rule long since approved by this Court in applying the Constitution and laws of the United States is that streams or lakes which are navigable in fact must be regarded as navigable in law; that they are navigable in fact when they are used, or are susceptible of being used, in their natural and ordinary condition, as highways for commerce, over which trade and travel are or may be conducted in the customary modes of trade and travel on water; and further that navigability does not depend on the particular mode in which such use is or may be had-whether by steamboats, sailing vessels or flatboats-nor on an absence of occasional difficulties in navigation, but on the fact, if it be a fact, that the stream in its natural and ordinary condition affords a channel for useful commerce. The Montello, 20 Wall. 430, 439; United States v. Cress, 243 U. S. 316, 323; Economy

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