delivered the opinion of thé court.
This case presents some questions of jurisdiction and constitutionality arising out of the relative rights and duties,of’ the city of Chicago and the West Chicago Street Railroad Com*514pany in respect of a tunnel maintained by that company under the South Branch of Chicago river, at or near Van Burén street in that city.
The judgment in the Circuit Court of Cook County, Illinois, was in favor of the railroad company, but it was reversed in the Appellate Court, First District, the.former court being directed to give to-the city the relief asked. Upon appeal to the Supremé Court of Illinois a judgment was rendered in favor of the city.
The contention of the company is that the judgment under review cannot be sustained consistently either with the contract clause of the Constitution .of the United States or with the due process of law enjoined by the Fourteenth Amendment.
The case presented by the record is substantially as will be now stated.
On or about April 2, 1888, the City. Council of Chicago adopted in due form the following ordinance :
“Whereas, the board of directors of the West Chicago Street Railroad Company, on the second day of April', 1888, by and at the request of the Mayor of the city of Chicago, adopted the following resolution: Resolved, That the West Chicago Street Railroad Company, in consideration of the passage and approval by the Mayor of the three ordinances passed by the City Council of- Chicago on the thirtieth day of March, 1888; one granting to the West Division Railway Company the right to change its motive power from horse to cable or electric power; one granting to the Chicago Passenger Railway Company the right to make the same change; and one granting to the West Chicago Street Railroad Company the right to construct its tracks on Jefferson street between Madison and Washington streets, and to use horse, cable or electric power thereon, hereby agrees by and with the city of Chicago at its own expense to construct a tunnel 'under the Chicago river and acquire the necessary right of way therefor on a route to be located by;said company between Madison and Twelfth streets, with the east terminus at Fifth ¿venue or west thereof,, and *515the western terminus at Halsted street or east thereof; provided, however, that this company shall have the right from said city to construct said tunnel under any intervening street or streets and said river within said limits, but such location and construction shall be such as not to. interfere with the capacity, usefulness or grade of said streets; said tunnel to be used by this company for street railroad tracks, and the construction thereof shall be commenced within three.years and be completed within four years after the said City Council shall grant permission to said railroad company to make said improvements, unless prevented by injunctions or strikes,- and the time said construction is so interfered with shall be added to said four years, all work to be done-in a maimer satisfactory to the Commissioner of Public Works, and the tracks through the tunnel,shall be connected with the street railroad tracks controlled by this company. Now, therefore, be it ordained, by the City Council: That the agreement in said resolution contained be and the same is hereby accepted by and on behalf of the city of Chicago as a. consideration from said company for the passage and approval by-the Mayor of the ordinances in said resolution specified, and authority is hereby granted said company to make the improvements therein mentioned.-”
When this ordinance was passed there was in force what is known -as the Horse and Dummy Act,, passed in 1874, which provided: “That any company which has been or shall be incorporated under the general laws of this State, for the purpose of constructing, maintaining or operating any horse or dummy railroad or tramway, may enter upon and appropriate any property necessary for the construction, maintenance and'oper-b ation of its road, and all necessary siding, side, tracks and appurtenances, and may,, subject to the provisions contained in this act, locate and construct' its road upon or over any street, alley, road or highway, or across or over any waters in this State, in such manner as not to unnecessarily obstruct the public use of such street, alley, road or highway, or interrupt the navigation of such waters.”
*516In West Chicago Street R. R. Co. v. The People, 214 Illinois, 9, 19, the Supreme "Court of Illinois, referring to this act, said: “This act was an addition to the charter of any company organized under the general incorporation act, and its provisions have existed under some form ever since; conferring powers, upon street railroad companies organized as the defendant is. It gave the defendant the right to construct its railroad either over or across the . Chicago river, which included -the tunnel, subject to the condition contained in it. Defendant could only hold real estate for the transaction of its business of maintaining and operating a street railroad, and the-statute fixed the conditions under which it might use its real estate for building the tunnel. ”
The tunnel was completed by the railroad company in March, 1894, and has ever since been used and is now being used as a passageway under the river for its cars. When constructed (as well as at the present time) the water in the South Branch of the Chicago river over the tunnel near Van Burén street varied in depth from seventeen to eighteen-and three-tenths feet.
On the third day of March, 1899, Congress passed a River and Harbor Act, among the provisions of which was one directing the Secretary of War to cause surveys to be made and the cost of improving certain rivers and harbors to be estimated and reported to Congress, as follows: “Improving Chicago river in- Illinois: survey and estimate of cost for .a channel twenty-one feet deep from its .mouth to the stock yards, on the South Branch, and to Belmont avenue, on the North Branch so far as may be permitted by existing docks and wharves, exclusive of .cost of removing or constructing bridges or piers or lowering tunnels; and the aforesaid depth of twenty-one feet is hereby adopted as the project depth for the improvement in lieu of that fixed by the act of June third, eighteen hundred and ninety-six; Provided, that all the,work of removing and reconstructing bridges and piers and. lowering tunnels necessary to permit a practicable channel with said depth to *517be obtained shall be done, or caused to- be done, by the city of Chicago, without expense to the United States. ” 30 Stat. 1121, 1156.
After the passage of that act steps were taken to dredge the Chicago river so as to deepen its channel in accordance with the provisions of the act of Congress, and, it is alleged, such work “has been proceeding under the authority and supervision of the Government of the United States, for the purpose of providing a sufficiently deep channel for the uses and purposes of commerce and navigation as aforesaid. ”
For the purpose of obeying the act of Congress, and in order to .obtain a free and unobstructed navigation of the Chicago river for the benefit of commerce, interstate and domestic, the City Council of Chicago, on the nineteenth day of March, 1900, duly passed the following ordinance: “ Whereas, by act of Congress of March 3,,1899, it is provided that in the survey ánd esti- . mate of cost for a channel twenty-one feet deep, in the improvement of the Chicago river from its mouth to the stock y^rds on the South Branch, and to Belmont avenue on the North Branch, the aforesaid depth of twenty-one feet is adopted as the project depth for such improvement; whereas, io is'in said act further provided that all the work of removing ánd reconstructing bridges and piers and lowering tunnels necessary to permit a practicable channel with said depth to be obtained, shall be doxle or caused to be done by the city of Chicago, without expense to the United States; whereas, the tunnel under' the South Branch of the Chicago river at Van Burén street was constructed by the West Chicago Street. Railroad Company under a certain ordinance of the city of Chicago, passed April 2, 1888; whereas, a channel in the Chicago river, of the depth of at least twenty-one feet is now made necessary by the requirements of navigation and by the increase ip the draft of vessels engaged in the-shipping trade of the Lakes; whereas, the said tunnel is an obstruction to said proposed improvement to the Chicago river and to the navigation thereof, and as such obstruction must be lowered so that there-may be above it in *518said river a depth of at least twenty-one feet of water,, or be removed altogether: Now, therefore, be it ordained by the City Council of the city of ChicagoThat the West Chicago Street Railroad Company be and it is hereby .ordered and directed within three months after the date of the passage of this ordinance, at the sole cost and expense of said West Chicago Street Railroad Company and without cost, damage, loss or expense of any kind, whatsoever to the city of Chicago, to proceed to lower the tunnel under the South Branch of thé Chicago river at or-near Van Burén street,, being the same tunnel heretofore constructed by the said West Chicago Street Railroad Company under an agreement dated April 2, 1888, between the said West Chicago Street Railroad Company and the city of Chicago, and an ordinance passed by the City Council of the' city of Chicago, April 2, 1888, authorizing the construction of said tunnel in accordance with the. provisions of said agreement, so as to provide for' a clear depth above said tunnel of at least twenty-one feet of water at all times. Said work shall be performed by the-said West Chicago Street Railroad Company under the supervision and direction and subject to the approval of the Commissioner of Public Works of the city of Chicago, and shall be completed on or before March 1, 1901.”
In execution of the provisions of that ordinance the city caused notice to be given to the railroad company, demanding compliance • with its provisions. The company did not heed that notice.
The present action was thereupon instituted by the people of Illinois, on the relation of the city of Chicago, against the railroad company. The^ specific relief asked was the issuing of a writ of mandamus directing the railroad company, without cost, damage, loss or expense of any kind whatsoever to the city, to proceed to lower its tunnel under the South Branch of the Chicago river at or near Van Burén street, so as to provide for a. clear depth above it of at least twenty-one feet of water at all times; for its entire width and length, or to wholly remove it “ so that the same shall cease to be an obstruction to the free *519navigation of said Chicago river or the South Branch thereof,' and to perform said work under the supervision and direction^ of the Commissioner of Public Works of the city of Chicago. ”
The Circuit Court found the issues for the defendant, and . denied the. application for a mandamus. Upon error to the Appellate Court, First District, the judgment of the Circuit Court was reversed and the cause remanded with directions “ to¡ issue a writ of mandamus commanding the railroad company to remove its tunnel, said writ not to be executed until, the Washington street and La Salle street tunnels are both removed or lowered to á sufficient depth to be no longer an .obstruction to navigation.”
' Upon appeal to the Supreme Court of Illinois a final judgment was there entered awarding a peremptory writ of mandamus as prayed for in the petition. West Chicago Street R. R. Co. v. People, 214 Illinois, 9.
• As explanatory of the reference to the -tunnels on Washington and. La Salle streets it may be here stated that those tunnels belonged to the city, and were located bétween the tunnel at Van Burén street, owned by thé railroad company, and the . mouth of the river ,at the Lake. -Of course, until the city’s ' tunnels are lowered or removed, the lowering or removal of the tunnel on Van Burén street would not be of material aid to navigation.
We come now to consider the questions arising on the record and discussed at the- bar.
1. The-contention of the city that the writ of error should be dismissed for want of jurisdiction in this court cannot be sustained. It is true that the judgment of the state court rests partly upon grounds of local or general law. But, by its necessary operation — although the opinion of the state court does not expressly refer to the Constitution of the United States— the judgment rejects the claim of the company, specially set up in its answer, that the relief asked by the city cannot, in any view of the case, be granted consistently, either with the contract clause of the Constitution or with the clause prohibiting *520the State from depriving anyone of his property without due process of law. If that position be well taken, then a judgment based merely upon grounds of local or general law would be error; for, the Federal questions raised cover the whole case, and are of such a nature that' the rights of the parties could not be finally determined without deciding them. As the judgment, by its necessary operation, denied the company’s claims based on the Constitution of the United States, this court has jurisdiction to inquire whether those claims are sustained by. that instrument. Our views on this question are fully stated in Chicago, Burlington & Quincy R. R. Co. v. Drainage Commissioners, 200 U. S. 561.
2. Great stress is placed by the railroad company on the fact that it is the owner, in fee of the bed of the' river at the point where the tunnel was constructed. But that’ fact is not vital in the present discussion; for it was ádjudged by the state court — in harmony with settled doctrines, as will presently appear — that “ the title to land under a navigable river is not the same as the title to the shore land; ” that “in a navigable ' stream the public right is paramount, and the bwner of the soil under the bed of such a stream can only use and enjoy it in so far as is consistent with the public right, which must be, free and unobstructed;” that “the title to the upland is absolute and paramount, while the title to the lands over which the navigable water flows is subordinate to the public right of navigation;” and that “the city could not, if it would, grant the right to obstruct the navigation of the river, or bind itself to permit anything which has become an obstruction to be continued.” 214 Illinois, 9, 20, 21.
3. We next consider the first of the strictly Federal questions raised by the company. Its contention is that the tunnel was constructed under a valid contract with the city, evidenced by the ordinance of 1888, and that the, mere order to remove or lower the tunnel impaired the obligation of that contract, in violation of the Constitution. .
Upon a careful scrutiny of the ordinance of 1888, we find no *521clause or provision which' so restricted the power of the -city that it could not require the railroad company to lower or remove the tunnel when the public interests, as involved in the unobstructed navigation of Chicago river, demanded that to be done. The railroad company, in consideration of certain rights and privileges granted to it by the city, undertook to construct the tunnel; and it is true that when constructed the tunnel did not interfere with navigation; nor would it now obstruct navigation, if only boats and vessels of the size and capacity in use when the tunnel was constructed were engaged in commerce on the river. But such boats and vessels are insufficient to meet the present needs of commerce at Chicago. The business of that city has enormously increased since, the passage of the ordinance of 1888, and, admittedly, the tunnel is now an obstruction to free navigation on the river by boats and vessels of large size. The railroad company may have believed, when the ordinance of 1888 was passed, that the tunnel would never interrupt or obstruct navigation. Nevertheless, the ordinance did not expressly or by necessary implication bind the city to -forbear the exercise of any power it had to deepen the channel of the river and thereby improve navigation. As the city could not legally adopt an ordinance inconsistent with a statute of the State, we must read into the ordinance- of 1888 that part of the act of 1874 which, as construed by the Supreipe Court of Illinois, made it a condition of the right of a street railroad company to cross its cars through a tunnel under Chicago river that its road and tunnel should be so located and constructed ¿snot unnecessarily to interrupt navigation.. Apart from any question as to the power of the city to bargain away or surrender its authority to improve navigation and protect it against obstruction, the railroad company must be held to have accepted the ordinance and constructed the tunnél subject to the requirement that navigation should not be interrupted by it. As the present tuxrnel is an obstruction to the use of the river by many boats and vessels employed in commerce on the Lakes, and as, by the ordinance *522in question, the city did not stipulate — even if it could lawfully have stipulated — that it would not exert whatever powers it had in order to protect the free navigation of Chicago river whenever it became necessary or proper to do so, the result must be that the execution of the order to lower or remove the tunnel would' not impair the obligation of any contract protected by the Constitution of the United States. If, in the ordinance of 1888, the city had stipulated that it would meet the expense of any alteration of the tunnel made by its direction, a different question would have been presented. But the ordinance cannot be construed as containing such a stipulation, and consistently with the settled doctrines of this court no such stipulation can arise from mere implication. There is, in our judgment, no ground whatever for holding that the city, by the ordinance of 1888/ came under the obligation of a contract to meet the cost of any changes in the.tunnel that might be lawfully required in order that the river ¿ould be safely navigated by large vessels.
4. This brings us to the principal question in the case: Whether, consistently with the Constitution of the United States, the railroad company can be required to lower or remove the tunnel in. question and (if it continues .to use a tunnel in crossing Chicago river with its cars) to construct and maintain, at its own expense, such a tunnel as will conform to the provisions of the ordinance of March 49, 1900.
It is indisputable, on this recprd, that the depth of water over the present tunnel is not sufficient to accommodate many boats and vessels now commonly employed in commerce between Chicago and other cities and towns on the Lakes. It is -to be taken also as indisputable that in order that such boats and vessels may navigate the South Branch of Chicago river with safety, the depth of water over the Van Bmen street tunnel must be at'least as great as that specified in the city ordinance of Í900. We assume also — as by the record we may properly do — that the, ordinance is a reasonable, not an arbitrary exertion of the power conferred on the city “ to construct and keep *523in repair bridges, viaducts'and. tunnels and to regulate the use thereof, ” and “ to deepen, widen, dock, cover, wall, alter and change the channel of watercourses. ” We must, in addition, upon this record, assume that the means adopted by the city have a direct, real and substantial connection with the public ' object intended to be accomplished, namely, to free the navigation of the South Branch of Chicago river from an obstruction which prevents the use of that river by vessels of the size demanded by The vast business transacted at Chicago.
As already observed, the contention of the company is, in ■ éffect, that even if the present tunnel be an obstruction to the navigation of the river by large vessels, the lowering or removal of the tunnel against the company’s will, would be a taking of private property for public use without compensation, in violation of the constitutional guarantee of due process of law.
This result, it is supposed by the railroad company, necessarily follows from the fact that the present tunnel was constructed with the assent of the city, and when constructed was sufficient for purposes of navigation by vessels, of whatever size, then engaged in commerce on the Chicago river. But these facts are not all that must be considered in this discussion. They cannot be considered apart from other matters of a vital character, namely: That the city was under the duty of. protecting the free navigation of the river and its branches — a duty from the discharge of which it could not be exempted by any agreement it might make with the railroad company; that the city granted the right to construct the present tunnel under the river subject to the condition, necessarily implied by the statute of 1874 in force when the ordinance of 1888 was adopted, that the tunnel should not interrupt navigation; that if the assent of the company to such a condition was important, it must be held to have given such assent by accepting the ordinance of 1888, into which, as already indicated, must be read the requirement in the statute of 1874 that navigation should not be unnecessarily interrupted; and that the provision in *524that statute forbidding any interruption of the navigation of the river had reference to the needs of navigation not only at the time the tunnel was constructed, but its needs at any subsequent period as found and declared by the city, upon reasonable grounds; which declaration would, of course, be subject to the condition, vital in our system of government, that the courts'may look through and behind mere forms, and interfere, whenever necessary, for the protection-of-private rights against an illegal, arbitrary exercise of governmental power.
In addition to these considerations we may suggest the important one that the rights of the company, as the owner of the fee of land on either side of the river or in its bed, were subject to the paramount right of navigation over' the waters of the river. Weber v. Harbor Com’rs, 18 Wall. 57, 66; Illinois Central R. R. Co. v. Illinois, 146 U. S. 387, 458; Shively v. Bowlby, 152 U. S. 1, 30; Gibson v. United States, 166 U. S. 269, 276; Scranton v. Wheeler, 179 U. S. 163; C., B. & Q. Ry. Co. v. People, 212 Illinois, 103; Brazen v. Bressler, 64 Illinois, 488; People v. Vanderbilt, 28 N. Y. 396; Sage v. Mayor, 154 N. Y. 61; State v. Parrott, 71 N. Car. 311; State v. Dibble, 4 Jones (N. C.), 107; Diedrich v. Northwestern &c. Ry. Co., 42 Wisconsin, 248; Parmeter v. Attorney General, 10 Price, 412; Williams v. Wilcox, 8 Ad. & El. 314; Colchester v. Brooke, 7 Q. B. 339. The principle is thus declared by a leading text-writer: "The privilege of- navigation upon all waters which are capable of such use in their natural condition and are accessible without trespassing upon private lands, is a common and paramount right. . . . At common law the right of navigating a public stream is paramount to the right of passage across the stream by means of a bridge/’ Gould on Waters, §§ 86, 88.
If, then, the right of the railroad company to have and maintain a tunnel under the Chicago river is subject to the paramount public right of navigation; if its right to maintain a tunnel in the-river is a qualified one, becáuse subject to the specific condition in the act of 1874 that no tunnel should interrupt navigation; if the present tunnel is an obstruction to *525navigation, as upon this récord we must take it to be; and if the city, as representing the State and public, may rightfully insist that such obstruction shall not longer rémain in the way of free navigation; it .necessarily follows that the railway company is under a duty to comply with, the demand made upon it to remove, at its own expense, the obstruction which itself has .created and maintains. If the obstruction cannot be removed except by lowering the' tunnel to the required depth and (if a tunnel is to be maintained) providing one that will not interrupt navigation, then the cost attendant upon such work must be met. by the company. The city asks nothing more than that the railroad company shall do what is necessary to free navigation from an obstruction for which it is responsible, and (if it intends not to abandon its right to maintain a tunnel at or near Van Burén street) that it shall itself provide a new tunnel with the necessary depth of water 'above it. The case differs somewhat from Chicago, Burlington & Quincy Ry. Co. v. Drainage Commissioners, 200 U. S. 561, just decided. In that case we held it to be the duty of the railway company, at its own cost, to remove the bridge, culvert, timbers, and stones which it placed in Rob Roy creek, and which prevented the execution of the plan devised by the Drainage Commissioners. But the. Commissioners demanded that more be done; for, their plan contemplated that earth outside of the railroad bridge and culvert be removed, in order that the channel be enlarged, widened and deepened. But in that improvernpnt •the railway company had no interest. It was not responsible for the inadequacy of the original channel of Rob Roy creek for the system of drainage adopted, by the Commissioners. Its only duty, and the only burden imposed upon it, was to- remove, at its own cost, the obstructions placed by it in the creek, and which stood in the way of the proposed system of drainage. In the case before us the public demands nothing to be done by . the railroad company except'to remove the obstruction which itself placed and maintains in the river under the condition that navigation should not at any time be thereby in*526terrupted. The removal .of such obstruction is all that is needed, to protect navigation. So that whatever cost attends the removal of the obstruction must be borne by the railroad company. The condition under which the company placed its tunnel in the river being met by the company, the public has no further demands upon it. This cannot be deemed a taking of private property for public use or a denial,of the equal protection of laws within the meaning of the Constitution, but is only the result of the lawful exercise of a governmental power for the common good. This appears from' the authorities cited in Chicago, Burlington & Quincy R. R. Co. v. Drainage Com’rs, supra, just decided.1 The state court has well said that to maintain the navigable character of the stream in a lawful way is not, within the meaning of the law, the taking of private' property or any property right of the owner of the soil under the river, such ownership being subject to the right of free and unobstructed navigation. People v. West Chicago Street R. R. Co., 203 Illinois, 551, 557. What the city asks, and all, that it asks, is that the railroad company be required, in the exercise of its rights and in the use of its property, to respect the public needs as declared by competent authority, upon reasonable grounds, to exist. This is not an arbitrary' or unreasonable demand. It does not, in any legal sense, take or appropriate the company’s property for- the public benefit, but only insists that the company shall not.use its property so as to interrupt navigation.
Further discussion of the general question will5' be found in *527Chicago, Burlington & Quincy. R. R. Co. v. Drainage Com’rs, supra, jüst decided. We need not repeat all said in the opinion in that case on this question.
Another matter requires no ticé. The railroad company con-. tends that the city had no power to require or authorize any changes in the bed of the river without the approval of the Secretary of War. River and Harbor Act of 1899/ § 10; 30 Stat. 1151. The same act contains directions for the improvement- of Chicago river. Construing all the provisions together, we think it clear that when Congress declared in the River and Harbor Act of 1899, under the' heading of “ Improving Chicago riverin Illinois,” p. 1156, that “all the 'work of removing and reconstructing bridges and piers and lowering tunnels necessary to permit a navigable channel” with.the prescribed “project” depth of twenty-one feet in Chicago river should be done by the city, without expense to the United States, it meant to give the assent of the United States to any work done by the city towards accomplishing the end which the Government had in view. The state court properly said that “ the city has power, under-its charter, to deepen the channel, and as a preliminary to doing so, to require' this tunnel to be. lowered or removed, and the act of Congress permits it to proceed, so far as the lowering of the tunnel is concerned. ” .
As showing that the action taken by the city of Chicago is in accordance with the will of Congress, wé may refer to the act of Congress of April 27, 1904, relating to. certain tunnels under Chicago river, including the particular tunnel here in question. That act provides: “That the tunnels under the Chicago river in the State of Illinois at La Salle street, Washington street, and near Van Burén street, in the city of Chicago, in said State of Illinois, áre, and each of them is hereby, declared' to be, as now constructed, an unreasonable obstruction to the free navigation of said Chicago river, and each of said tunnels is hereby declared to be a public nuisance. And it shall be the duty of the Secretary of War to give notice to the persons or corporations owning or controlling said tunnels, or any of them, so to *528alter the same as to render navigation over said tunnels free, easy, and unobstructed, ;and in giving such notice he shall specify the changes recommended by the Chief of Engineers that are needed to be made in order that said tunnels, or any-of them, shall not thereafter be an obstruction to navigation, and shall prescribe in each case a reasonable time in which to make said changes. If at the expiration of such time such changes have-not been made, the Secretary of War shall forthwith notify the-United States District Attorney for theNorth- . ern District of Illinois, in which said tunnels are situated, to, the end that the criminal proceedings hereinafter prescribed may be taken. If the person or persons, corporation or corporations, owning or controlling any of the said tunnelá shall, after receiving notice to that effect, as hereinbefore required, from the Secretary of War, and within the time prescribed by him, fail or refuse to remove the same or to make the changes specified in the notice of the Secretary of War, such person or persons, corporation or corporations, shall be deemed guilty of a misdemeanor, and on. conviction thereof shall be punished by a fine not exceeding ten thousand dollars; and each and every, month such person or persons, corporation or corporations, shall remain in default in respect to the removal or alteration of such .tunnel shall be deemed a new offense and subject the person or persons, corporation or corporations, so offending to the peiialty herein prescribed: Provided> That in any case arising under the provisions of this act an appeal or writ of error may be taken from the District Court or from the Circuit Court direct to the Supreme Court either by the United States or by the defendants.” 33 Stat. 314. For some reason, not ex- , plained -in the record, no allusion was made to this act in the opinion of the Supreme Court of Illinois, nor is it alluded to in in the briefs of counsel. That act, it seems to the court, emphasizes and strengthens the vieyys expressed in this opinion, and tends to support the conclusions reached.
For the reasons we have stated, and in Conformity with the principles announced in Chicago, Burlington & Quincy R. R. *529Co. v. Drainage Com’rs, the judgment of the Supreme Court must be affirmed.
It is so ordered.