This is an application to take land for public use under the flowage act. Judgment was rendered for the plaintiffs, and the defendants appealed.

After the committee reported in favor of the plaintiffs, the defendants under the statute required the court to inquire for itself whether the erection of the proposed dam would be of public use. On the hearing before the court *459the defendants offered to prove that the waters of the stream were polluted by the refuse and sewage from the villages and manufacturing establishments above; that they carry in suspension large quantities of vegetable and animal substances, which will be carried over and deposited on the additional lands so flowed, and which will ferment under the effect of the sun and heat, as the pond is drawn down in its daily use, and cause offensive odors and noxious gases to arise to the great injury of the comfort and health of the inhabitants. Evidence on that subject was objected to by the plaintiffs, and excluded by the court.

Was that evidence properly excluded? Did it tend to prove any fact put in issue by the pleadings ? The complaint alleges that “ the raising of said dam and the consequent flowing of said land will be of public use.” That paragraph the defendants deny. That presents the whole issue in respect to the public use. It is not set up as a defense that the flowing of the land as proposed will be of injury to the public health. Can that fact be proved without pleading it? In other words, is the effect upon the public health involved in the question of public use ? It certainly is not if that issue is limited to the question whether the business carried on results in the “production of an article or thing intended to be furnished or sold to the public for a beneficial use, and to supply their reasonable wants.” If we enlarge the scope of the issue, as the plaintiffs’ counsel suggest was done in this case, so as to authorize the additional inquiry as to “the size of the mill, the capital invested, the amount of daily production, its value, the necessity of flowing the defendants’ land for the uses of the mill, the pay-roll for the plaintiffs’ operatives, and the collateral benefits which the public would receive from the operation of the plaintiffs’ mill,” still we fail to find any ground for the claim that evidence is admissible as to the effect upon the public health. The issue does not even suggest such an inquiry. The streams of this state are not yet so extensively polluted as to afford any presumption that the detention of water for manufacturing *460purposes will be detrimental to the public health. Hence it is not expected that the plaintiffs will be prepared in the first instance to offer proof on that subject, especially as any proof that they will be likely to offer will necessarily be of a negative character. If in any given ease the ponding of water will be injurious, we apprehend that it is exceptional and not the rule. If so it is a matter for the defendants in their answer to bring to the attention of the court. They take the affirmative of that issue. In offering proof to sustain it they offer nothing in conflict with the plaintiffs’ evidence that the proposed enterprise will be of public use. It is in the strictest sense matter of avoidance. The defendants practically say.—true it is that your proposed mill will be of public use, but you ought not to be permitted to erect it and carry on your business because it will result in a nuisance which the courts must abate. It seems to us therefore that this is a matter wholly distinct and independent of the issue presented by the pleadings. It has no necessary or natural connection with it. If it is brought into the case at all, therefore, it must be brought in by the defendants in their answer as a defense. As that was not done the evidence was not admissible.

We do not intend to intimate that a defense of this character would probably be successful, or that it would not. It is as yet perhaps an open question how far the pollution of such a stream is unhealthy. Admit that it may be so to those living on its immediate banks, yet neither observation nor science has told us how far the deleterious influence extends. We apprehend that it is mainly a question of fact; and when such a defense is once established as a fact, then perhaps it will be for this court to determine whether a case so situated is an implied exception to the operation of the flowage act.

It is claimed in the second place, that the court erred in authorizing the plaintiffs to flow the land of the defendants to the injury of a mill-site owned by them.

The plaintiffs deny that the defendants have any mill-site. The facts found by the committee relating to this *461claim may be briefly stated as follows:—The plaintiffs’ dam is on Hockanum river, about three miles below its junction with Hop brook. About forty years ago Sidney Olcott conceived the scheme of constructing a dam across Hop brook about one mile above its mouth, and taking the water therefrom by means of a canal to a point below the confluence of the two streams, and then using it for mill purposes, discharging the water into Hockanum river. In 1862, in pursuance of this scheme, he built a dam across Hop brook, and at intervals did some work on the proposed canal for a period of about three years. His sister then owned the land on which the dam was built, and also the land at the lower end of the canal. She never favored the scheme, nor did she intend to engage in manufacturing herself; and she refused to sell her land to Sidney Olcott for that purpose. In 1869 this dam was partially destroyed by a flood, and in the course of three years was carried away to such an extent as to leave no substantial obstruction to the flow of water. In 1872, after the death of his sister, he purchased the land which had belonged to her, with a view to develop and carry into effect his scheme for a mill at the mouth of the proposed canal, but nothing more was done until after the bringing of this suit, when some work was done for the purpose of affecting the determination of the suit. The defendants never had any definite plan as to the time when the proposed mill should be constructed, as to the size or kind of mill, nor as to the business to be carried on. There was land on the opposite side of Hop brook, below the defendants’ dam, which was owned by other parties, who had a right to insist that the water should flow by and past their lands as it had been accustomed to do. “ Upon these facts ” the committee say, “ we do not find that on the stream on which the plaintiffs’ dam is, there is any mill site on which a mill dam has been lawfully erected and used, which will be injured by the erection of the plaintiffs’ dam.”

The committee however left it for the court to determine otherwise as a conclusion of law, and made a finding as to *462the effect of the plaintiffs’ dam upon such a mill-site. We think the committee correctly disposed of it as a question of fact. Sidney Olcott certainly had no mill-site prior to 1872, because he did not own the land, and the owner neither contemplated nor desired the erection of a mill, and refused to sell her land for that purpose. After 1872, although he owned the land, yet he had no mill-site, for he coidd not lawfully divert the water from the down stream proprietors.

In the next place, the defendants contend that the court erred in allowing the amendment of December 23d, 1881, increasing the height of the dam prayed for, from four feet to four feet and eight inches, and in passing a decree allowing the dam to be raised to that height.

It will be observed that the objection to the allowance of the amendments relating to the description of the land to be taken is not pressed. No objection seems to have been made to the amendment relating to the height of the dam at the time. When the report of the committee was returned to the Superior Court, the amendment itself was not objected to, but the defendants filed a motion in writing that the facts found by the committee relating to all the amendments be stricken out. The court denied that motion. In this court, while the reasons of appeal allege that the court erred in allowing the amendment increasing the height of the dam prayed for, the arguments of counsel under this head do not relate to the allowance of the amendment, but are limited to a question as to the construction and effect of the amendment. Even that question does not seem to have been raised in the court below. Nevertheless, as the question is free from doubt, we will express our opinion. The principle involved is, that if an amendment, if allowed to take effect as of the date • of the original bill, will affect injuriously the rights of parties, it will be regarded as taking effect at the date of the amendment, and that the suit, to the extent of the amendment, will be regarded as pending only from that time. In order to avail themselves of this principle the defendants must make it appear that they *463had a mill-site, or some right or interest in one, at the date of the amendment, which they did not have at the commencement of the suit; and for that purpose they assume that they once had a mill-site which they had lost or partially lost by non-user, and that the assertion of their right by labor performed in 1881 rescued their privilege or some portion of it from the consequences of their inaction, or that such labor in some way gave them some rights which they did not have before or preserved some rights which would otherwise have been lost. This is a mistaken assumption ; for it is not found, and we do not hold, that they once had a mill-site which has been lost or partially lost by abandonment or otherwise, but it is found, and we do hold, that they never had a mill-site. Consequently the principle referred to can have no application.

From this view of the case it is obvious that the error of the court, if it be one, in refusing to erase from the committee’s report the facts relating to the amendments, is immaterial. Those facts have no bearing upon the question here discussed. They tend to show that the amendments were properly allowed, but that question, as we have seen, is not now before us.

The defendants further contend that “the court erred in passing the decree without ordering the payments required by the statute to be made before flowing the defendants’ land.” It appears in the case that in January, 1882, the plaintiffs, at the defendants’ suggestion, the dam having been then constructed to the height asked for, filled the pond with water for the purpose of ascertaining how much land would be flowed. The plaintiffs afterwards refused to draw off the water and have kept up the pond ever since.

The eighth section of the flowage act provides that the damages and costs shall be paid “ before the water is flowed upon such lands, and within sixty days after the proceedings on said petition are ended ; and if such damages and costs are not so paid or deposited, the whole proceedings shall be of no effect.” The decree requires the damages, *464&c., to be paid “ in accordance with the provisions of the statute in such case provided.”

The defendants’ grievance seems to be that the court did not require the pond to be drawn down before passing the decree. We think that was a matter between the parties outside of the proceedings before the court. The statute requires the damages to be first paid; but it does not declare in terms that flowing the lands before the damages are paid vitiates the proceeding. Whether such a construction is required by implication we need not now determine, as we are of the opinion that a refusal by the plaintiffs to draw off the water from the defendants’ land, after having flowed it at their request, will not have that effect.

There is no error in the judgment.

In this opinion the other judges concurred.