(specially concurring).
While the end result reached by the majority in reversing the trial court is in accord with my views, our reasons for arriving at the same conclusion are only partly in harmony. It is my belief that the resultant discord is of such transcendency that I am compelled, with all due deference to the majority, to separately state the rationale for reaching that conclusion.
The majority has indicated that it is unable to examine the claimed non-responsibility of the city for increased surface water draining into the arroyo because of artificial developments in areas outside the city and over which it had no jurisdiction or control, for the reason that the city failed to comply with Rule 51(a) requiring that exception be taken to the refusal to give requested instructions. The objection that Rule 51(a) had not been complied with was first raised by the Appellees in their “Memorandum of Additional Authorities” which was handed to the court at the time of oral argument, more than a month after appellants’ Reply Brief had been filed.
No formal request for leave to file additional points as distinguished from additional authorities was requested or granted by the court as provided in Subdivision 3 of Rule 5(f) of the Rules of this court. 17 A.R.S. That objection should properly have been made a part of Appellees’ Reply Brief, as it presents a proposition of law that would normally be raised in the briefs.
The subject which the majority declines to consider had been extensively briefed by both sides and leave of court had been *359granted amicus curiae to argue the issues raised by the briefs before the objection was raised. It is my view that if technical rules are to be applied this court should take the position that no leave has been granted to present at such a late date the objection that Rule 51(a) has not been complied with. Particularly, since the questions raised in the briefs are of such importance to the rapidly expanding municipalities of Arizona, technical disposition of such issues should be avoided. For an interesting illustration of how this court has heretofore deviated from the stringent requirements of Rule 51 (a) see the case of Tipton v. Burson, 73 Ariz. 144, 238 P.2d 1098.
The evidence is undisputed that the development outside the city, and over which it had no control, principally in the area of Davis-Monthan Field, resulted in an increased flow of approximately 900 cubic feet per second in the Tucson Arroyo. Most of that development occurred subsequent to World War II and long after the completion of the culvert in 1931. It goes without saying that no engineer who undertook to design a culvert on the Tucson Arroyo in 1925, in the exercise of ordinary care, could have reasonably anticipated the establishment of and the extraordinary developments at Davis-Monthan Field. If a city undertakes and does all that it is able, in the judgment of its governing body, to correct a condition sought to ’be eliminated, it should not face potential liability from that time on into the distant future for flood damages caused by increased flow occurring from changed conditions entirely outside of its borders and beyond a reasonable foreseeability. To invoke such a rule would bring about a stalemate in any improvement on the part of municipalities in flood control.
It has been suggested by counsel for the City and by amicus curiae, in effect, that this court re-examine its holdings in City of Tucson v. Apache Motors, 74 Ariz. 98, 245 P.2d 255, and City of Tucson v. O’Rielly Motor Co., 64 Ariz. 240, 168 P.2d 245, because the rule announced in the O’Rielly case was based on an incomplete presentation of the facts, which re-examination the majority has done up to a point. The O’Rielly case was relied on by this court for its statement in the Apache Motors case that
“This constitutes a judicial finding of fact that the culverts in question were negligently constructed in that they were too small to carry away the flood waters which naturally flowed down the arroyo as the result of occasional rainfalls upon the watershed drained by said arroyo. It is therefore res judicata as to that fact.” [74 Ariz. 98, 245 P.2d 260.]
*360The use of the term “res judicata” was technically incorrect inasmuch as no privity of parties existed between the litigants in the O’Rielly case and the City of Tucson v. Apache Motors, except insofar as the facts therein announced were adopted in the Per Curiam memorandum opinion in the first City of Tucson v. Apache Motors case reported in 64 Ariz. 251, 168 P.2d 253. Since we are not confronted with any privity of parties in this appeal the doctrine of res judicata is of course inapplicable. 30 Am. Jur. 908, et seq.
The O’Rielly case presented a situation wherein the City offered no evidence in its «defense as to the carrying capacity of the culvert. In the instant case the City had numerous witnesses, both expert and lay, who testified that the natural arroyo overran its banks during flood season on a number of occasions prior to the installation of the culvert. Furthermore it appeared in the O’Rielly case that a great accumulation of debris was in the tunnel in addition to pipes and sewer mains. In the instant case no evidence of an accumulation of debris appeared, but on the contrary the testimony was that the City kept the channel relatively free of brush or debris, and had eliminated most of the pipes and mains in the culvert.
The majority has taken as true the testimony of one of the engineers who stated that in his opinion the capacity of the culvert was 2700 cubic feet per second. An examination of the witness’ testimony reveals that that estimate -yvas based upon a double 8' x 10' culvert, while the uncontroverted facts showed that the mouth of the culvert was a double 10' x 10' for a distance of over 40 feet, where it reduced to a double 8' x 10'. The only engineer who took into account the true dimensions of the culvert estimated its carrying capacity at 3,490 cubic feet per second. The estimated carrying capacity of the arroyo at the time of the flood in question varied from the maximum of 3,920 cfs in the swirl area at the intake of the culvert to 3,300 cfs at 101 feet east of the culvert, to 3,670 cfs at 213 feet east of the culvert, to 1,575 cfs 766 feet east of the culvert, to a mere 1,250 cfs 1,190 feet east of the culvert.
From the foregoing estimates it would appear that there was sufficient evidence to entitle the City to the instructions, which it requested and the trial court refused, to the effect that a city which installs a culvert or other structure in an arroyo or natural stream is not required to provide a capacity of such structure in excess of the natural volume capacity of the arroyo or stream. In other words, if the floodwaters would have overflowed the banks of the arroyo for a reasonable distance of the defined channel, whether the city structure were there or not, there should not be any liability imposed upon the City. If the *361stream or the arroyo would have overflowed had the city done nothing, how then can it be said that the city’s installation of the culvert was the cause of plaintiff’s injuries?
In applying the rule quoted by the majority from the case of City of Tucson v. Apache Motors to the effect that the city was required to build culverts of sufficient size to adequately carry away all water accustomed to flow or which may be reasonably anticipated to flow down such an arroyo as a result of the rains upon the watershed which it drained, it seems reasonable to define such flow as that which could normally be carried within the confines of the arroyo for a reasonable distance, and any flow which the city could establish exceeded the volume capacity of the arroyo for a reasonable distance should be characterized as such flow which could not reasonably be anticipated.
In addition to the foregoing observations it is my view that the flowage easement constituted a defense available to the City which, as indicated by the majority, had not been abandoned or waived. Whether on a retrial a trial court as a practical matter can segregate the damages as suggested by the majority is a matter of grave doubt.