The opinion of the court was delivered
by Lowrie, J.The law of the erection of the dam is, that it shall not obstruct or impede the navigation of a stream; or, in other words, that the artificial construction shall be such as not to lessen the natural degree of its navigability, so as thereby to obstruct or impede navigation to the injury of others. The dam, of course, must produce a change from the old condition of the stream; but it must not lessen its navigability. Its natural navigability must be the best measure of its navigability after the dam shall be erected. In so far as navigable before, it must be after erection.
It was, therefore, an essential element of the plaintiffs’ case, that by the erection of the dam the natural navigability of the stream was lessened to his injury. When the old condition of the stream is a necessary part of the inquiry, and the law demands an inquiry between the old and new, in order to ascertain if the old is injured by the change. If it is not, the dam is not an impediment to the navigation, and the plaintiff cannot recover.
We may take any stage of water, and say if at that stage the stream was not navigable at the place where the dam is, then the dam cannot be an impediment to any one in navigation. If there was no navigability there before, the dam makes it no worse for navigation. A dam is not an impediment to navigability created by and depending on the dam. It is no wrong that the dam stops navigation at the foot of the pool, if without the pool there could be no navigation. Craft that could not be .navigated there at a given stage of water before the dam was built, cannot be said to be impeded by the dam at a similar stage. Before the dam was built, people suited their craft to the natural navigability of the stream, and they are not injured if such craft so suited can still navigate with equal safety at a given place and stage of water.
The learned judge must have been understood by the jury to deny these principles, and in this his instructions were erroneous.
Judgment reversed, and a new trial granted.