dissenting.
I agree generally with the views expressed by Mr. Chief Justice Stone in the opinion written by him, except for the disposition which he makes concerning the claim of the City and County of Denver. The case is of sufficient importance to require a statement of my conclusions, reached after careful study, even though they must appear in the form of a dissenting opinion.
Detérmination of Denver’s claims depends upon three main propositions: First: As of what date did Denver initiate its water rights? Second: During what period thereafter did Denver exercise reasonable diligence toward perfection of the initiated water right? Third: What amount of water did Denver appropriate?
Under the contentions made by the parties the following pertinent questions of law are raised: (a) Can a water right relate back to a date prior to the time of the first physical work thereon which would, by its location and appearance, give notice of an intention to appropriate water to those having an interest in the *423waters involved? (b) To what extent can a claimant of water change his plan of development without that change amounting to a relinquishment of his claim? (c) May a claimant of water offer evidence to show that the water claimed is part of an interrelated system involving other water rights and, if so, is work on various parts of such interrelated system to be considered in determining the diligence with which each of the components in the water rights in the system is being developed? (d) Can the appropriator of water for direct and immediate use temporarily detain such water for his operational purposes without such detention being classed as “storage,” and, if so, to what extent?
I will state my views upon the questions as briefly as possible in the order above mentioned.
First Question.
Can a water right relate back to a date prior to the time of the first physical work thereon which would, by its location and appearance, give notice of an intention to appropriate water to those having an interest in the waters involved?
This question should be answered in the affirmative. Physical work on a water appropriation, which would put others on notice that water from a natural water course was being, or about to be, diverted for beneficial use is clearly one method by which all interested may be put on notice of the initiation of a water right. It is not the exclusive method, however. In recent years, and especially with respect to water projects of any considerable magnitude, the more usual method has been by making- a filing in the office of the State Engineer.
Of necessity, the first physical activity relating to the creation of a water right is the act of going upon the ground to examine what is to be done. Such physical manifestation, in the case of a small project might be followed up immediately with commencement of construction of diversion works, and the activities, all taken together, be ample evidence of the intent to appropriate *424which would put other potential appropriators on inquiry.
As this Court pointed out in DeHaas v. Benesch, 116 Colo. 344, 181 P. (2d) 453, such work, when carried to completion by the application of water to beneficial use, results in the creation of a water right dating back to the first work, without the necessity for ever filing any map or statement in the office of the state engineer or the clerk and recorder. In DeHaas v. Benesch, supra, there was nothing to indicate that the work of the appropriator was attached to any particular claim of right to water, for the water was commingled with the waters of other appropriations and carried in the same ditch. Yet, we there held that the true test of appropriation was the successful application of the water to beneficial use and not the appearance of the means of accomplishing that application.
This Court has held that physical work giving the appearance of a start on the creation of an appropriation did not constitute adequate evidence of such a start where not in good faith. Fruitland Irrigation Co. v. Kruemling, 62 Colo. 160, 162 Pac. 161. The converse also is true. Physical work, undertaken in good faith, though not appearing to relate to an appropriation, should be considered as evidence of an appropriation if, with all the other circumstances, it appears that it was actually a part of a good faith effort to make an appropriation.
Reasonable diligence in the creation of a large water diversion and use project demands adequate planning as the first step>. Initiation by field survey has had the approval of this court, as the first step from which a water right may properly be dated. Taussig v. Moffat Tunnel Co., 106 Colo. 384, 106 P. (2d) 363. Such a field survey might or might not indicate, by its appearance, the nature or extent of the proposed appropriation. It might not even appear to be a survey for a water right project at all, yet, if made in good faith and followed up with *425due diligence, would constitute the first step, and consequently would date the beginning of the project.
Under these circumstances, it is greatly to the advantage of the public that some means be provided for recording the meaning of such surveys. As early as 1881 provision was made for filing a record of the work of such surveys in the office of the state engineer. The early statute even went so far as to destroy the effect of commencement of a water right by survey if the record of the survey had not been made of record with the state engineer within sixty days of commencement of the work. This penalty was dropped in the amendatory Acts of 1903 and 1911 for the obvious reason that if all the work required by law, now appearing as section 29, chapter 90, ’35 C.S.A., were to be performed, it would be impossible to have it in the office of the state engineer within sixty days of its commencement in the case of a work of any magnitude. The statute itself recognizes this, and requires a preliminary filing, but again without penalty for failure to comply. It follows that work on a water diversion project is not lost to the would-be appropriator because what he does, does not appear on the ground to be work on an appropriation, or because he does not file the record thereof in the office of the state engineer within sixty days. In fact, if the work departs from the appearances it is not lost to the appropriator as part of his effort. I quote as follows from the opinion in DeHaas v. Benesch, supra: “Whether or not ditches were constructed in- accordance with the filings of maps and statement * * * was * * * not of the substance of the appropriation.”
If the statute attaches no penalty to the failure to file a map and statement within a prescribed time, it is not for this court to impose one, especially since, as pointed out in DeHaas v. Benesch, supra: “The statute further provides that nothing therein contained shall be construed to the injury of those having rights prior to those of claimants, or so construed as to prevent a proper ad*426judication of rights in accordance with existing laws governing such adjudications.”
Second Question.
To what extent can a claimant of water change his plan of development without that change amounting to a relinquishment of his claim?
As will be seen from the question in DeHaas v. Benesch, supra, there are some changes which can be made in the plan of a water development which will not constitute a relinquishment of the project. One criterion for determination of this problem was used by the United States Supreme Court in the case of Wyoming v. Colorado, 259 U. S. 419, where the changes planned had to do with the determination of “whether” the would-be appropriator would proceed at all with the diversion project. Such changes are to be distinguished from those which go rather to selection of the most economical or effective means to be employed for the accomplishment of a diversion and use of water, concerning which there already is a fixed and definite intention to take. Once the decision has been made to proceed with the project, continuing investigations and changes are simply evidence of diligence and endeavor to accomplish the greatest good at a minimum of cost to the public, not abandonment of the project.
This Court has adopted a liberal rule in this regard. In the Taussig case, supra, at the time of the adjudication proceedings neither the purp&se nor place of use of the water ultimately proposed to be diverted was known. As we there pointed out, before a final decree can be entered these uncertainties must have been eliminated. That is to say, before the right could be completed, the plan of construction existing at the time of the adjudication would have to be modified so as to include the means of making beneficial use of the water involved. Such a situation does not preclude the rendition of a conditional decree or work a relinquishment of the right. In fact, as we pointed out in the Taussig case, a condi*427tional decree may be necessary to furnish that “reasonable assurance” essential to financing a private project. We see no reason why public funds are not entitled to equal assurance.
The question under discussion cannot be answered in terms applicable to all controversies. The facts must govern each individual case. The basis for examining the facts, under the law of Colorado as announced by this Court over the years, may well include the following: (a) The appropriator’s acts should evidence a fixed and definite intention to take a fixed amount of water for application to a beneficial use. (b) A change in plan, which indicates a lack of fixed purpose or which shows only a general desire without a fixed determination to fulfill the desire, would not support an appropriation, (c) Changes undertaken with the apparent intent to improve or make more efficient or less costly the whole work to be undertaken, should be regarded as the natural diligence of a prudent man rather than the want of constancy in the prosecution of the undertaking.
Within these three pertinent principles I think it is abundantly clear that, at least from and after the 19th day of October, 1927, the City and County of Denver made no change in its plan to develop- the water right claimed, which would amount to a relinquishment of the plan and purpose then fixed upon to appropriate 1600 second feet of water.
Third Question.
May a claimant of water offer evidence to show that the water claimed is part of an interrelated system involving other water rights, and, if so, is work on various parts of such interrelated system to be considered in determining the diligence with which each of the component water rights in the system is. being developed?
This question must be answered in the affirmative. With respect to the development of a water right to irrigate a single piece of. land through a single ditch- to which water is diverted through one headgate, it would *428be obvious that diligence could be shown by reference to work on any, or all, of the three component parts: diversion dam, carrying ditch, or distribution laterals.
As the works become more complex, including several sources of supply, wider spread uses, and a variety of purposes, a project may cross county lines, irrigation district or irrigation division lines, and different jurisdictional lines for adjudicating the water rights involved. It does not appear that there is any point at which a water system becomes so large that its parts no longer relate to each other in such a way that work on one part may not constitute diligence with respect to completion of the whole including its other parts. It may well be that a single entity may have holdings so extensive that many of them are unrelated to others. In such a case, work on one holding would not constitute work on an unrelated holding.
It appears, therefore, that the test of the extent to which work on one part of a water system may properly relate to another for the purpose of determining due diligence, is whether the parts of the work relate to a single integrated purpose intimately enough that progress on one part has a direct bearing upon another part. What we are really considering is whether or not the work done is within the limits of what is reasonably to be considered as customary to an enterprise unified under single management and in which impairment of any part tends to directly impair the remaining parts, or in which construction of one part directly contributes to the whole which is comprised of other parts.
Much of the evidence which was admitted, and that which was erroneously excluded, established the fact that the city of Denver has one interrelated water system which should have been considered as a whole in so far as the question of reasonable diligence of the city in going forward with the Blue River diversion is concerned. Even without the full delineation of fact which might have been presented had the trial court not re*429stricted evidence to the Blue River unit alone, the only evidence in the record concerning Denver’s efforts shows a continuing good faith endeavor to accomplish the appropriation for which she now seeks a conditional decree. Arguments of counsel, pro or con, cannot take the place of evidence.
The majority opinion gives lip service only to the proposition that in the matter of diligence of the city in going forward with the Blue River diversion, its activity in the development of other arms of the system should be considered. This appears in the majority opinion in the following language: “Therefore, diligence in the prosecution of the Fraser and Williams Fork projects cannot be imputed to the Blue River projects. However, the fact that the city of Denver was engaged in the construction of these other projects may properly be considered together with other evidence as to existing facilities and ability of the city in determination of the issue of reasonable diligence.” By this language the majority opinion brushed off most pertinent and undisputed evidence, as well as facts concerning which this Court has judicial knowledge, concerning the desperate need, in the early years of the 1930 decade, for speedy increases in the water supply of the city, and the heavy demands upon the city for completion of developments of other related works for the diversion of water from streams tributary to the Colorado river. The majority opinion comments that: “There was no evidence of any effort by Denver to finance the project prior to the year 1946, but only of efforts to induce the United States to do so.” Unmentioned is the fact, which every citizen then living well knows, that in 1929 the whole nation trembled and lay prostrate in depression; that the public treasuries were empty; that for years thereafter any attempt to finance such a large undertaking upon the local level would have been sheer folly; and that the only hope for resources sufficient to warrant a start at construction was to seek the financial backing of the United *430States. In those years all business, both public and private, looked only to Washington for rescue from total collapse.
At about the time when another approach to the financial problem might reasonably have been expected to succeed, World War II broke out and thereafter for several years the productive energies of all the people were concentrated on the war effort. Men and materials were not to be had for any development of this kind, which could possibly wait. Just as soon as the conflict ended and war demands relaxed, construction of the tunnel began, and, despite inadequate financing and disappointments, the city has gone forward with the work. Thus, although the majority opinion declares that, in determining 'diligence on the part of the city, this Court “may consider” the other substantial emergency activities of the city to meet the demands of its residents for water, “together with all other evidence as to existing facilities and ability of the city” to go forward on the Blue River diversion, it is very apparent that the opinion fails to give any serious thought to those facts and circumstances. To my mind it is clear, as a matter of law, that under the undisputed facts shown by the record and from other pertinent facts judicially known to this Court, that the city has been diligent in its efforts to divert water from the Blue River, and that the majority opinion, to the contrary, is patently erroneous. .
From an examination of the whole record it appears that Denver, with respect to its Blue River project has done what might reasonably have been expected of any city similarly situated. In 1939, in Denver v. Sheriff, 105 Colo. 193, 96 P. (2d) 836, this Court said, inter alia: “It is not speculation but the highest prudence on the part, of the city to obtain appropriations of water that will satisfy the needs resulting from a normal increase in population within a reasonable period of time.” With the metropolitan population now at about 600,000 these words of fifteen years ago seem prophetic. In the Sheriff *431case we also said: “The furnishing of an adequate supply of water to 350,000 people requires managerial judgment and involves an ever-changing problem.” This is no less true today, with the increased population condition, and furnishes an approach to the one serious challenge to the good faith of the city in seeking the water supply involved here.
Fourth Question.
Can the appropriator of water for direct and immediate use temporarily detain such water for his operational purposes without such detention being classed as “storage,” and, if so, to what extent?
This question brings us to a consideration of a new and somewhat novel legal problem involved in Denver’s claim. Stated in another way the question is: Can Denver substitute a mechanical equivalent for the proposed 1600 second feet tunnel?
Under the decisions of this Court it has been established that one who owns the right to> divert water for direct and immediate use may not lawfully divert water under such right for the purpose of storing it for use at some indefinite future time. Under our law the owner of a water right does not have the right to divert a given quantity of water continuously, but only when circumstances are such that he can make beneficial application of it to use. When a water right owner does not need water, his right gives him no right to divert; but the water which he might be entitled to if he needed it must be allowed to flow to other appropriators who do need it. Hence the rule against storing on a right originally appropriated for immediate and direct use. The trial court limited Denver’s diversion to an amount which can be diverted through a tunnel of the size it is currently drilling, 788 second feet.
Denver’s filing map, which is its Exhibit “B,” contains as the sixth representation on it: “The method of construction contemplated (for the tunnel) is to first drive a heading of economic dimensions and then to en*432large and line the tunnel to its full size.” Denver’s testimony is that from an engineering standpoint the enlargement of the tunnel can be accomplished by the substitution of a mechanical equivalent, to wit: a forebay of sufficient size to temporarily impound the difference between the 1600 second feet appropriated and the 788 second feet, which the present tunnel will carry, until lessening of the runoff in the Blue River and its tributaries at Dillon affords leás than 788 second feet of flow, after which the forebay would gradually lose its contents. Denver’s testimony was that if such a mechanical equivalent is prohibited because of our law against storing water appropriated for direct and immediate use, the idea of a reservoir or forebay would be dropped and the city would enlarge the tunnel as stated in Exhibit “B.” The testimony was that a saving of $10,000,000 could be made under the substitute plan. We must therefore examine the circumstances to ascertain whether or not the proposal contemplates a lawful operating detention or an unlawful storage, in view of the principles discussed under the fourth point above.
Under the testimony, Denver’s proposed appropriation is for 1600 second feet. There is no evidence whatsoever that the 788 second feet awarded by the trial court is correct. By confining the amount of water decreed to 788 second feet, the trial court simply ignored the evidence that Denver was building the present tunnel as the first step toward a 1600 second foot diversion, and that there were two alternate methods of increasing the capacity from 788 second feet to 1600 second feet, one of which was the use of Dillon reservoir as a forebay, and the other was a physical enlargement of the 788 second feet tunnel.
It is my conviction that the plan of the City and County of Denver for the accumulation of water in the Dillon reservoir during the season of peak flows, with subsequent withdrawal at a rate permissible by the tunnel capacity, does not violate the rule against the storage *433of direct flow of water. This Court has held on. numerous occasions that the impoundment of ditch water diverted into a canal upon the ditch’s decree for direct irrigation cannot be made the basis for obtaining an independent and separate storage right. Greeley & Loveland Irrigation Co. v. Huppe, 60 Colo. 535, 155 Pac. 386.
The cases denying the right to store direct flow water all involve irrigation uses. They are cases in which the owner of a decreed right for direct irrigation seeks later to utilize the ditch, through which such water is conveyed, as a feeder to a reservoir and to obtain for the reservoir a right of the same priority date as that for the ditch. New Loveland & Greeley Irrigation & Land Co. v. Consolidated Home Supply Ditch & Reservoir Co., 27 Colo. 525, 62 Pac. 366; Windsor Reservoir & Canal Co. v. Lake Supply Ditch Co., 44 Colo. 214, 98 Pac. 729; Finley v. Cache La Poudre Irrigation Co., 44 Colo. 234, 98 Pac. 173; Greeley & Loveland Irrigation Co. v. Huppe, 60 Colo. 535, 155 Pac. 386, or cases involving injunction suits to restrain storage of water decreed for direct irrigation as against other rights. Greeley Co. v. Farmers Pawnee Co., 58 Colo. 462, 146 Pac. 247; Handy Ditch Co. v. Greeley & Loveland Irrigation Co., 86 Colo. 197, 280 Pac. 481. Holbrook Irrigation District v. Fort Lyon Canal Co., 84 Colo. 174, 269 Pac. 574, is not in point because there, by the consent of the parties, a direct irrigation right was not decreed to a feeder canal. (See opinion on Rehearing, 84 Colo. 197.)
None of the cases mentioned above involves municipal uses under a gigantic project such as that proposed by Denver. In the case at bar Denver seeks to divert 1600 c.f.s. from the Blue River-and its tributaries and transport that water through the Continental Divide by means of a tunnel which has a capacity of 788 c.f.s. Water diverted through the collection system will be accumulated in the Dillon reservoir and allowed to flow from it at a rate permissible under the tunnel capacity. The reason for this method of operation is that the cost of a *434tunnel to carry 1600 c.f.s. is some $10,000,000 in excess of the cost of the Dillon Reservoir and of the smaller tunnel.
This is not a case in which water covered by a direct irrigation right is sought to be stored for future use with the priority date for such relating back to the decreed priority date of the direct irrigation right. Rather this is a case in which, in an adjudication suit, the city seeks a conditional decree permitting the diversion and use of a defined quantity of water for municipal purposes. The impoundment of this water in the proposed Dillon reservoir will not adversely affect any other water users because there is and will be no increase in the quantity of water, measured by volume and time, which the city would be entitled to divert annually if it had a tunnel with the capacity of 1600 c.f.s. (Seven Lakes Reservoir Co. v. New Loveland & Greeley I. & L. Co., 40 Colo. 382, 93 Pac. 485). As there will be no increase in the total annual quantity of water taken over that which might be taken by a tunnel with 1600 c.f.s. capacity, there is no reason why Denver should be required to expend an additional $10,000,000.00 in order to satisfy a rule of law heretofore applied in cases involving irrigation of lands in which the facts were altogether dissimilar from those present in the case at bar. This Court will not close its eyes to practical considerations.
Unquestionably the City of Denver would have the right to appropriate the 1600 cubic feet per second of water by the construction of a tunnel of that capacity. This objective could be attained with no ground for opposition by the expenditure of an additional $10,000,-000.00 of the people’s money. If the same result can be obtained by the substitution of a mechanical operational equivalent to the larger tunnel I am at a loss to understand why the increased burden upon the taxpayers should be required. In the last analysis the result would be the same and the rights of other appropriators would in no wise be jeopardized.
*435It is no answer to the above to assert that Denver applied for and was awarded a storage decree for impounding water at the Dillon reservoir, and that, “One cannot add water to a full cup, and may not have a second decree for water from the same source to be held at the same time in the same reservoir to which a decree already has been awarded to its full capacity.” This statement quoted from the majority opinion is plausible enough but it fails substantially to present the whole picture. One most certainly can have a full cup of water which is subject to the application of two rules of law governing the use to which the water in the cup may be put. If the direct flow decree permits withdrawal of the water from the cup under a priority date of 1927 one result is obtained which would be entirely different from securing a full cup of water under a storage decree with a priority date many years subsequent to 1927. Thus the illustration of the “full cup” fails to hold water.
The majority opinion treats the Dillon reservoir as a storage unit capable of filling under its very late decree. Actually the unquestioned fact is that this reservoir as a storage unit is so junior to other users that it could be expected to impound water on its storage decree only on the rarest of occasions. In all normal operations the Dillon dam would serve two functions: One as a head-works for diverting Denver’s direct appropriation through the tunnel; and two, for catching an occasional flood in the late summer. There is nothing in our law to the effect that a dam may not be used both as a head-gate and as a storage control. In fact the same structure often is used for both storage and direct uses in the case of ditches. Many ditches carry storage water to off-stream reservoirs and also to supply direct appropriations. The same ditch and headgate frequently have both storage and direct decrees attached to them. The identical structure carries both kinds of water. A ditch of a capacity of 500 second feet may one day carry 500 second feet to a reservoir on a storage decree and the *436next day carry 500 second feet on an entirely different decree for direct uses. There is no reason why the Dillon dam cannot fulfill in succession both the diverting and the storage functions. If any quantity of water amounting even to a fraction of that awarded the Dillon dam under its storage decree could actually be relied upon under the late priority of that decree, there would be no controversy for determination before this Court.
In conclusion Mr. Justice Holland has authorized me to announce his full concurrence in this opinion and to further say that he would have included the municipality of Colorado Springs.in this dissent, and in addition thereto to add the following observation, which is, in his language, as follows:
“In the last analysis the pivotal question involved in determining the 'conflicting claims that have arisen in this litigation is ‘diligence.’ In other words, priority rights stand or fall upon a determination of the question of reasonable diligence in connection with the perfecting of different claims. In this regard, I have an indelible impression that there should be a different and more liberal approach to the question of diligence when applied to municipalities in their efforts to carry out their governmental duty and function of obtaining and supplying water for their inhabitants. Our statutes and the decisions of our Courts have been geared largely to the matter of appropriation of water for irrigation purposes, and by virtue of such statutes and decisions, there has been, and now appears in the majority opinion, an infringement .upon the truly domestic use of water. It is advantageous and profitable to a farmer to have water for the development and maturity of his crops; however, it is fundamentally more important that people congregated in a municipality have water to sustain life itself, as well as health and safety. A municipality cannot prevent thousands of people taking up their abode in a city, and the domestic- need is at once presented. To meet this all important matter of providing water for *437domestic consumption, vast plans must necessarily be conceived, studied and tested, and finally, financed to accomplish the required result. This is not a matter of overnight arrangement, so to speak, but necessitates far more consumption of time and, in many instances, change of original plans than is required to arrange for the taking of water from a stream or streams to be employed on lands for agricultural purposes. On the part of a municipality it may by necessity become a large integral system, the perfection of which demands changes for feasible, physical reasons, as well as economic considerations. Such would be entirely different from the more simple matter of declaring an intention to appropriate water for field use and following that intention in a reasonable time with some physical demonstration of carrying the intention forward. What might rightfully be determined reasonable diligence in the liberal sense application on the part of a municipality with such plan, could properly be considered negligence on the part of appropriators for other purposes. It is my firm conviction that our statutes and decisions should be retimed to meet the actual necessities of life that are inescapable in a city in its attempt to care for a mass of humanity. We find water regulations imposed upon city dwellers when no rigid restrictions are imposed upon the takers of water for other purposes under their decreed rights. I ally myself on the side of the individual and his vital needs for life itself as against industrial plants, mountains of trees and fields of grain. The individual would have little need for the latter if he could not have a drink of water. We are taken back to the firmly established proposition that first things come first. By the strict application of our present water statutes and the adherence to decisions that have not taken or allowed any more liberal approach to the question of diligence in these appropriation matters as they relate to a municipality, do we further hasten the day when the growth of cities is halted, and by such a standstill, allowed to *438wither on the vine, while water may freely be taken under old priorities, allowed to run across the land, and finally back to the sea, while the city dweller’s tongue may parch with thirst.”
For the foregoing reasons I am of the opinion that the City and County of Denver is entitled to a conditional decree for 1600 cubic feet per second, with a priority date as of October 19, 1927.
Mr. Justice Holland and Mr. Justice Knauss concur in this dissent.