Opinion by
The plaintiff is the owner of a tract of land in Indiana county bordering on the Conemaugh river. With a view to straighten and otherwise improve its line of road, the defendant company appropriated by condemnation proceeding something over four acres of this land. At this point the defendant company constructed a bridge for its roadbed over the river. The near abutment and two of the piers rested on the land which had been appropriated, the second pier being near the low water lines; the other piers, four in number, rested on the bed of the river. Evidence was offered by the plaintiff and ad*482mitted, tending to show that the erection of the bridge had changed the current of the river; that whereas, before this Obstruction to the flow was placed there, the current was against the opposite bank, it is now in consequence of the obstruction turned in the direction of plaintiff’s land, with the result that in stages of high water and ordinary freshets a considerable part of plaintiff’s land is flooded and otherwise injured. This circumstance was claimed and allowed as an element of damage to be considered by the jury, provided they found the facts to be as above stated. The assignments of error, excepting one to be considered later, all relate to this ruling. The company’s contention is, first, that it is exempt from liability for injury resulting from the erection of the bridge, inasmuch as the structure was erected pursuant to a franchise from the commonwealth over a stream the bed of which was in the commonwealth exclusively; and, second, that if liable at all, it can only be for such consequences as are shown to have resulted from so much of the bridge structure as rests upon the plaintiff’s land. The state’s participation in the matter does not affect the case in the least. The franchise granted the defendant company carried with it a right to use the bed of the stream for the necessary piers; but it did not and could not exempt the party exercising the franchise from liability for injury to property not belonging to the state but to private parties, occasioned by the bridge. The cases are numerous in which this court has held that the rights of the railroad company to build a bridge across a stream, includes the right to place necessary piers on its bank and in its bed; and that for the proper exercise of this right there is no liability; the most recent of these cases being Braine v. Northern Cent. Ry. Co., 218 Pa. 43, in which the earlier cases are cited. But this exemption extends no further than to relieve from liability for such interference with ordinary and natural conditions in and upon the stream, as affects the rights of the public in the stream, or the rights of riparian owners to access *483to the stream. An examination of the cases referred to will show that in every one of them the subject of the injury complained of was within the proper limits of the stream. In several the injury was to boats or barges; in others the matter complained of was interference with the right of access, or with a privilege exercised in connection with the stream under grant. Any such doctrine as here contended for would violate constitutional safeguards with respect to the ownership of private property. When land is flooded by the erection of a bridge over a navigable stream and its value thereby impaired, it is in effect a taking of the land itself, and for any taking of land for public use, compensation is the condition. The flooding of land continuously, or even intermittently, caused by the construction of a dam or of other erections for public use, is a taking which requires compensation: Pumpelly v. Green Bay Co., 80 U. S. 166. The right to flood the land of any one by the erection of piers in the bed of a stream, can only be adversely acquired as land itself is acquired, by giving or securing compensation to the party who would be injured thereby. Were this not so, a company having acquired a right from the state to erect and maintain a bridge over the stream — a right which necessarily carries with it the right to determine the character, number and location of the piers: Braine v. Northern Cent. Ry. Co., 218 Pa. 43 — might so obstruct the flow of the water with its bridge as to overflow a riparian owner’s land, not occasionally but constantly, in a way destructive of its value, and leave the owner remediless. That is not the law. What we have said is in answer to the second contention of the defendant as well. If none of the piers were on the condemned land, but all on the bed of the river, the defendant would nevertheless be liable for whatever injury the bridge as a structure worked to the plaintiff in the way of flooding his land. The evidence with respect to this was properly admitted.
The other assignment is better supported. The wit*484ness, Robert Nesbitt, called on behalf of the plaintiff to testify to the market value- of the plaintiff’s farm, was clearly incompetent, and his testimony should have been excluded. Not only did he repeatedly admit in his preliminary examination that he had no familiarity with the market value of land in the neighborhood, but when testifying in chief he as repeatedly said that the estimate he gave was not a market value, but a value based on what he thought the farm would produce. When asked how he arrived at the market value, his reply was that he-did not believe it right to consider market value; that he had his own notion as to what this land was worth, and was not governed by outside sales; that he estimated it from its earnings capacity, and that he could not confine himself in his estimate to market value. Thus the one standard by which the law measures damages in cases of this kind was distinctly repudiated by the witness. It was error to allow him to testify, and having testified not to a market value but to a value based on mere productiveness, his testimony should have been withdrawn from the jury. This assignment of error is sustained and judgment is reversed with a venire facias de novo.