Plaintiff city, the chief producer of water from a 40 square mile alluvial-filled basin of ground water* known as the Raymond Basin Area, instituted this litigation to determine the ground water rights within the area and to enjoin an alleged annual overdraft in order to prevent eventual depletion of the supply. Pursuant to section 24 of the Water Commission Act, which was then in force (Stats. 1913, p. 1012, as amended, Deering’s Gen. Laws (1937), Act 9091; now Wat. Code, §§ 2000-2050), the trial court referred the matter to the Division of Water Resources of the Department of Public Works for a determination of the facts, and the ensuing report of the division was received in evidence. On the basis of this report all of the nondisclaiming parties, with the exception of the defendant California-Michigan Land and Water Company, a public utility and the sole appellant herein, entered into a stipulation for a judgment allocating the water and restricting total production to the safe annual yield. The court, after hearing evidence presented by appellant in opposition to the report, rendered a judgment substantially enforcing the terms of the stipulation against all parties, including appellant.
The principal issues presented on this appeal are whether the trial court properly limited the amount of water that appellant may take from the ground in the Raymond Basin Area, and whether it erred in placing the burden of curtailing the overdraft proportionately on all parties. Before discussing these issues on the merits, we will consider certain contentions involving jurisdiction, procedure and remedy.
Preliminary Contentions
The complaint was filed on September 23, 1937, and the trial was not commenced until May 18, 1944. A dismissal is made mandatory by section 583 of the Code of Civil Procedure, except in certain cases, unless the action is brought to trial within five years after the plaintiff has filed his action. It is settled, however, that in computing the five-year period the time during which, “for all practical purposes, going to trial would be impossible, whether this was because of total lack of jurisdiction in the strict sense, or because proceeding to trial would be both impracticable and futile,” is to be excluded. (Christin v. Superior Court, 9 Cal.2d 526, 533 [71 *917P.2d 205, 112 A.L.R. 1153] [time consumed by appeal from order granting change of venue]; Pacific Greyhound Lines v. Superior Court, 28 Cal.2d 61, 64 [168 P.2d 665] [time during which one defendant was in military service and stay might have been granted]; Judson v. Superior Court, 21 Cal.2d 11, 14 [129 P.2d 361] [time defendant avoided service of summons by evasion and concealment]; Westphal v. Westphal, 61 Cal.App.2d 544 [143 P.2d 405] [time during which coplaintiff had an appeal pending].)
The order of reference was made on February 8, 1939; the referee’s report was filed on July 16, 1943, and, thereafter, respondents proceeded with reasonable dispatch to bring the cause to trial. The issues to be tried were dependent to a great extent upon the facts to be ascertained by the referee, and it would have been impracticable, if not futile, to proceed to trial prior to the completion of the report. It follows that the time consumed by the reference should be excluded in computing the five-year period, and that, therefore, the action was not subject to dismissal under the provisions of section 583.
The “Division of Water Resources, Department of Public Works, State of California,” was appointed as referee pursuant to section 24 of the Water Commission Act which provided: “In case suit is brought in any court of competent jurisdiction for determination of rights to water or the use of water, . . . the court may, in its discretion, refer such a suit to the state water commission for investigation of and report upon any one or more or all of the physical facts involved, in which event, said commission may, in its discretion, base its report solely upon its own investigation or investigations or in addition thereto may hold a hearing or hearings and take testimony and the report filed by the commission upon such a reference for investigation by it shall be prima facie evidence of the physical facts therein found. ...”
Every recent major water law decision of this court has expressly or impliedly approved the reference procedure provided by section 24 and has recommended, in view of the complexity of the factual issues in water cases and the great public interests involved, that the trial courts seek the aid of the expert advice and assistance provided for in that section. (See Fleming v. Bennett, 18 Cal.2d 518, 522 et seq. [116 P.2d 442] ; Meridian, Ltd. v. San Francisco, 13 Cal.2d 424, 457 [90 P.2d 537, 91 P.2d 105] ; Rancho Santa Margarita v. Vail, 11 Cal.2d 501, 558-559 [81 P.2d 533] ; City of Lodi v. East *918Bay Mun. Utility Dist., 7 Cal.2d 316, 341 [60 P.2d 439] ; Tulare Irr. Dist. v. Lindsay-Strathmore Irr. Dist., 3 Cal.2d 489, 575 [45 P.2d 972, 1014] ; Peabody v. City of Vallejo, 2 Cal.2d 351, 373-374 [40 P.2d 486]; Wood v. Pendola, 1 Cal.2d 435, 443 [35 P.2d 526].)
In sustaining and approving the reference procedure, it was stated in the Fleming case that “all of the pertinent constitutional safeguards were observed by the legislature in enacting the provisions of section 24. . . .” (18 Cal.2d at p. 528.) The opinion did not mention whether section 24 conflicted with article III, section 1, of the Constitution, which provides for the separation of powers, or discuss whether such an order of reference invalidly subjects an executive branch or division and its officers to the control of the judiciary. It was, however, expressly held (18 Cal.2d at pp. 523-525) that section 24 does not provide for the exercise of judicial power by the division, and implicit in the decision is the conclusion that the separation of governmental powers is observed. (See, also, Wood v. Pendola, 1 Cal.2d 435, 442 [35 P.2d 526].) In effect section 24 provides that the court may appoint the division to act as an investigator and an expert witness, but there is nothing which authorizes the courts to control or regulate, in any particular, the proper functions of the division or the manner in which, pursuant to legislative mandate, it shall proceed in conducting its examination and making its report. The Fleming case also expressly held that section 24 is not unconstitutional and void as a special law providing for a variation from the general practice and procedure in the superior court in violation of article IV, section 25, of the Constitution. (18 Cal.2d at p. 528; cf., Wood v. Pendola, 1 Cal.2d 435, 442 [35 P.2d 526].)
There is no merit in the contention that the reference should have been made to the Department of Public Works as the statutory successor of the Water Commission. Since the abolition of the Water Commission in 1921, it has been repeatedly recognized that, under section 24, the court may properly refer a pending water rights case to the Division of Water Resources or its predecessor, the Division of Water Rights.* (Fleming v. Bennett, 18 Cal.2d 518, 521 [116 P.2d 442]; Rancho Santa Margarita v. Vail, 11 Cal.2d 501, 559 [81 P.2d 533]; City of Lodi v. East Bay Mun. Utility Dist., 7 Cal.2d 316, 341 [60 P.2d 439]; Tulare Irr. Dist. v. *919Lindsay-Strathmore Irr. Dist., 3 Cal.2d 489, 575 [45 P.2d 972, 1014]; Peabody v. City of Vallejo, 2 Cal.2d 351, 373 [40 P.2d 486].)
The complaint is made that some of the men who worked on the report of the referee were not available for cross-examination at the time of the trial. It appears, however, that the man who prepared the report and supervised the investigation testified at length and that others who worked on the report also testified at the trial. Appellant was afforded ample opportunity to examine these witnesses, and there is no showing that it sought to obtain the testimony of persons who were not present. It was permitted to introduce evidence contrary to the facts appearing in the report, and, under all the circumstances, there was no denial of an opportunity to be heard in opposition to the report.
Appellant claims that the trial court improperly enlarged the scope of the proceedings. In response to a request of the referee for instructions, the court, after a hearing, ruled that the issues should “embrace an adjudication of rights of the defendants inter se and the rights of each and every party as against each and every other party. ’ ’ Although the answers of the respective defendants did not present claims against the other defendants and we.re not served on them, the action was tried on the theory that these matters were at issue, and the ensuing judgment limiting the amount of water that each could pump was also based on this theory. The trial court has authority, under section 24, to include, in the matters which are to be submitted to the referee and determined by the judgment, any issues necessary to a proper determination of the controversy. (See Fleming v. Bennett, 18 Cal.2d 518, 523 [116 P.2d 442].) It was within the discretion of the trial court to determine whether it was necessary to adjudicate inter se the amount of water to which each party was entitled, and the record indicates that it would have been impracticable to decide the matter solely between plaintiff and each defendant. Moreover, appellant had ample time to prepare its case after notice of the scope of the proceedings, and there is no basis for any claim that it was misled to its prejudice or that it was denied due process of law.
The objection is also made that the court erred in allocating water without the joinder of a number of private users who pumped comparatively small amounts. The referee filed a preliminary report which stated that it would be impracticable to attempt to include all such parties. It ree*920ommended, however, that certain named parties who used fairly substantial amounts be joined in the action, and the court ordered them brought in over the objections of appellant. No request was made by appellant for the inclusion of any party who had not been joined, and there is no showing that its interest was injuriously affected by the failure to require the joinder of all possible claimants. (See Smith v. Cucamonga Water Co., 160 Cal. 611, 617 [117 P. 764].) The line must be drawn somewhere in order to bring the proceeding within practical bounds, and it would have been impossible to reach a solution of the problems involved and to render a valid judgment if jurisdiction to make an allocation depended upon the joinder of every person having some actual or potential right to the water in the basin and its sources of supply. The persons not made parties are, of course, not bound by the judgment, nor are they injured by the injunction.
Appellant further contends that it cannot be enjoined since the water which it produces is devoted to a public use. Reliance is placed upon eases holding that when a public use has attached, inverse condemnation proceedings may be invoked and compensation in lieu of a prohibitory injunction is preferred in most circumstances. (See Hillside Water Co. v. Los Angeles, 10 Cal.2d 677, 688 [76 P.2d 681]; Peabody v. City of Vallejo, 2 Cal.2d 351, 377-380 [40 P.2d 486] ; Newport v. Temescal Water Co., 149 Cal. 531, 538 [87 P. 372, 6 L.R.A.N.S. 1098].) This rule has its foundation chiefly in the inconvenience to the public if service is interrupted by the issuance of an injunction to restrain the use (Miller & Lux v. San Joaquin L. & P. Corp., 8 Cal.2d 427, 436 [65 P.2d 1289]; Burr v. Maclay Rancho Water Co., 160 Cal. 268, 280 [116 P. 715]), and has no application to the problem which confronts us here. The purpose of this litigation is the protection of the interests of both public and private users by preventing further depletion of the water supply. Excepting appellant, all parties, public as well as private, have consented to be enjoined to effect this purpose. There is nothing in the record to indicate that the public interest would be better served by depriving private users of their pumping rights and compensating them therefor. If this were done they would have to purchase their water from municipalities or public utilities which take water from the same underground area, and the total supply available to the public would not be increased. Moreover, it would be exceedingly *921difficult to fix the monetary loss of each private party and then apportion it among the numerous public users. In these circumstances, the trial court was justified in concluding that the rule against enjoining public utilities was not applicable.
Findings and Judgment
The Raymond Basin Area, a field of ground water located at the northwest end of San Gabriel Valley, includes the city of Sierra Madre, almost all of the city of Pasadena, and portions of South Pasadena, San Marino, and Arcadia. The field of ground water contains alluvium consisting of sands, gravels and other porous materials through which water percolates. The northern side is formed by the San Gabriel range of mountains which rise back of the valley to a general elevation of from 5,000 to 6,000 feet. The area comprises 40 square miles and is separated from the rest of the valley along its southern boundary by the Raymond Fault, sometimes known as Raymond Dike, a natural fault in the bedrock constituting a “Barrier in the alluvium . . . which greatly impedes the sub-surface movement of water from the area, although it does not entirely stop it, thus creating a vast underground storage reservoir. ’ ’ There is a pronounced slope to the south from elevations of 1,000 feet above sea level at the mountains to a general elevation of 500 to 700 feet at Raymond Fault.
In this part of the state there is ordinarily a series of wet years followed by a number of dry years, making it necessary during periods of above-normal rainfall to store water for future use. It appears, however, that the ground water storage capacity is adequate to store the excess during wet years for the following dry years.
Natural underground formations divide the area into two practically separate units. The Western Unit, the larger of the two, consists of the Monk Hill Basin, which is to the northwest, and the Pasadena Subarea. The Eastern Unit, or Santa Anita Subarea, lies immediately to the east of the Pasadena Subarea. At the present water table elevations movement of ground water from the Western to the Eastern Unit is so small as to be immaterial but it might be increased by an overdraft in the Eastern Unit. Movement from the Eastern to the Western Unit is almost totally lacking.
Our concern is with the Western Unit where the principal ground water movement is from north and west of Monk Hill to the south and east and across Raymond Fault. The water *922in this unit is replenished by rainfall, by return water arising from the use of water in the unit, and by the runoff and underflow from the San Gabriel Mountains to the north and from the San Rafael hills to the west. Appellant’s wells, from which it obtains all its production, are in the southeastern part of this unit, and the underlying water constitutes one ground water body which is a common source of all parties taking water therefrom. The water pumped from the ground in the Western Unit has exceeded the safe yield thereof in every year since 1913-14 (commencing October 1) except during the years 1934-35 and 1936-37. The safe yield of the unit was found to be 18,000 acre feet per year, but the average annual draft was 24,000 acre feet, resulting in an average annual overdraft of 6,000 feet.
With respect to the water rights acquired by the various parties it was stipulated by all of them, including appellant, that all of the water taken by each of the parties to this stipulation and agreement, at the time it was taken, was taken openly, notoriously and under a claim of right, which claim of right was continuously and uninterruptedly asserted by it to be and was adverse to any and all claims of each and all of the other parties joining herein.”
The findings set forth in terms of acre feet per year “the highest continuous production of water for beneficial use in any five (5) year period prior to the filing of the complaint by each of the parties in each of said units, as to which there has been no cessation of use by it during any subsequent continuous five (5) year period.” This was designated, for convenience, the “present unadjusted right” of each party, and the court concluded that each party owned “by prescription” the right to take a certain specified amount of water, and that the rights of the parties were of equal priority. The total of the unadjusted rights for the Western Unit was found to be 25,608 acre feet per year, and water pumped by nonparties to the action was 340 acre feet per year. The court also found that a continued draft in these amounts will result in an unreasonable depletion and the eventual destruction of the ground water as a source of supply; that any increase in the amounts taken in the Eastern Unit will deplete the ground water supply in that unit; that in order to. protect the supply it is necessary that the parties in the Western Unit be limited by reducing the ‘ ‘present unadjusted right of each such party in the proportion that the safe yield of said unit, less the water taken therein by nonparties hereto, bears to the aggre*923gate of such rights of parties hereto in said unit, and that each of the parties pumping or otherwise taking water from the ground in the Eastern Unit be limited to the amount of its present unadjusted right.” The amount of water limited to each party, designated the “decreed right,” was set out in the findings, and this allocation gave each party about two-thirds of the amount it had been pumping.
The court enjoined all pumping in excess of the decreed right and appointed a “Water Master” to enforce the provisions of the judgment. It reserved jurisdiction to modify the judgment or make such further orders as might be necessary for adequate enforcement or for protection of the waters in the Raymond Basin Area from contamination.
Sufficiency of Evidence
Appellant takes the position that the ground water in the Western Unit is not contained in a single storage basin or reservoir as found by the court, but, rather, flows in certain defined underground streams from the northwestern portion to the southeastern section in much the same manner as water flows in surface streams, and that these streams, together with a flow of water from the Eastern Unit, converge at the lower level where appellant’s wells are located. It argues that its taking of water cannot possibly injure the upper claimants because once the water has reached a lower level it cannot flow back upstream to the wells of the other parties.
The report states that no substantial quantity of water from the Eastern Unit now reaches appellant’s wells. It also indicates that the ground water of the Western Unit is analogous to water stored in a large lake or reservoir, through which several currents slowly flow from inlet to outlet. Raymond Fault is similar to a dam in that it impedes the movement of water and backs it up over a considerable area, and pumping tests established that when the water table was lowered in one well, the effect could be measured in wells almost 2 miles away. These tests were conducted over comparatively short periods of time, the greatest being about three days, and since the water moves very slowly through the alluvium, it could be inferred that the effect would have been much more widespread if the test-pumping had been continued for a longer time.
There is nothing in the record which would compel a finding that the difference in elevation between the Monk Hill Basin and the Pasadena Subarea is so great that wells in the *924northwest will be entirely unaffected by long-continued excessive pumping elsewhere in the unit. Moreover, as the referee points out, the serious overdraft is in the area where appellant takes its water, and its pumping directly reduces the supply where water is most needed. The record shows that in view of the smaller overdraft in the Monk Hill Basin the parties situated there suffered a greater ratable cut under the injunction than persons in the Pasadena Subarea, and that appellant has been helped rather than injured by inclusion of the Monk Hill Basin as part of the underground storage area.
Appellant contends that the safe yield was greatly understated, and that there was little, if any, overdraft. Eighteen thousand acre feet per year was found to be the safe yield in the Western Unit, and this figure was based upon the report of the referee which calculated the amount from changes in-the water stored underground and in the water table elevation as compared with the amount of water extracted by pumping. It is asserted that the referee failed to measure and include the underflow from the San Gabriel Mountains and the waters conserved upon the surface by artificial means. All sources of underground water, however, were automatically included by the method of calculation employed by the referee, and it was not necessary to make the specific measurements mentioned by appellant. Moreover, it is obvious from many statements in the report that surface conservation and underflow were given full consideration by the referee.
The Main Issue
There can be no question that the trial court had authority to limit the taking of ground water for the purpose of protecting the supply and preventing a permanent undue lowering of the water table. (Burr v. Maclay Rancho Water Co., 154 Cal. 428, 438 [98 P. 260] ; City of San Bernardino v. City of Riverside, 186 Cal. 7, 16 [198 P. 784]; cf., Allen v. California Water & Tel. Co., 29 Cal.2d 466, 485-486 [176 P.2d 8].) The main problems presented are which of the parties should bear the burden of curtailing the total production of the unit to the safe yield and what proportion, if any, of the pumping by each particular party should be restricted. Since the stipulation made by the other parties as to the reduction in pumping by each is not binding upon appellant, it is necessary to determine appellant’s rights in relation to the other producers in the same manner as if there had been no agreement.
*925The question of who shall bear the burden of curtailing the overdraft, and in what proportion, depends upon the legal nature and status of the particular water right held by each party. Eights in water in an underground basin, so far as pertinent here, are classified as overlying, appropriative, and prescriptive. Generally speaking, an overlying right, analogous to that of a riparian owner in a surface stream, is the right of the owner of the land to take water from the ground underneath for use on his land within the basin or watershed; the right is based on ownership of the land and is appurtenant thereto. (See Hillside Water Co. v. Los Angeles, 10 Cal.2d 677, 686 [76 P.2d 681] ; Miller v. Bay Cities Water Co., 157 Cal. 256, 279-280 [107 P. 115, 27 L.R.A.N.S. 772]; 26 Cal.Jur. 271-277; 2 Wiel, Water Rights [3d ed., 1911], §§ 1100-1105, pp. 1040-1045.) The right of an appropriator depends upon an actual taking of water. (See 26 Cal.Jur. 277.) The term “appropriation” is said by some authorities to be properly used only with reference to the taking of water from a surface stream on public land for non-riparian purposes. (See Wiel, Water Rights [3d ed., 1911] §§ 228, 1107, 1158, 1159, and § 231 in the “reprint ed.” of the 3d ed.; Farnham, Waters and Water Rights [1904] § 672a; 56 Am.Jur. 599.) The California courts, however, use the term to refer to any taking of water for other than riparian or overlying uses. (City of San Bernardino v. City of Riverside, 186 Cal. 7, 13-14 [198 P. 784] ; Burr v. Maclay Rancho Water Co., 154 Cal. 428, 436 [98 P. 260] ; Katz v. Walkinshaw, 141 Cal. 116, 135 [70 P. 663, 74 P. 766, 99 Am.St.Rep. 35, 64 L.R.A. 236]; see 26 Cal.Jur. 273-274.) Where a taking is wrongful, it may ripen into a prescriptive right.
Although the law at one time was otherwise, it is now clear that an overlying owner or any other person having a legal right to surface or ground water may take only such amount as he reasonably needs for beneficial purposes. (Katz v. Walkinshaw, 141 Cal. 116 [70 P. 663, 74 P. 766, 99 Am.St.Rep. 35, 64 L.R.A. 236] ; Peabody v. City of Vallejo, 2 Cal.2d 351 [40 P.2d 486] ; Cal. Const., art. XIV, § 3.) Public interest requires that there be the greatest number of beneficial uses which the supply can yield, and water may be appropriated for beneficial uses subject to the rights of those who have a lawful priority. (Peabody v. City of Vallejo, 2 Cal.2d 351, 368 [40 P.2d 486].) Any water not needed for the reasonable beneficial uses of those having prior rights is excess or surplus water. In California sur*926plus water may rightfully be appropriated on privately owned land for nonoverlying uses, such as devotion to a public use or exportation beyond the basin or watershed. (Peabody v. City of Vallejo, 2 Cal.2d 351, 368-369 [40 P.2d 486] ; City of San Bernardino v. City of Riverside, 186 Cal. 7, 29, 30 [198 P. 784] ; Burr v. Maclay Rancho Water Co., 154 Cal. 428, 436 [98 P. 260] ; Katz v. Walkinshaw, 141 Cal. 116, 135 [70 P. 663, 74 P. 766, 99 Am.St.Rep. 35, 64 L.R.A. 236]; see 26 Cal.Jur. 32 et seq., 273-274.)
It is the policy of the state to foster the beneficial use of water and discourage waste, and when there is a surplus, whether of surface or ground water, the holder of prior rights may not enjoin its appropriation. (Peabody v. City of Vallejo, 2 Cal.2d 351, 368-369, 372 [40 P.2d 486]; see 26 Cal.Jur. 277.) Proper overlying use, however, is paramount, and the right of an appropriator, being limited to the amount of the surplus, must yield to that of the overlying owner in the event of a shortage, unless the appropriator has gained prescriptive rights through the taking of nonsurplus waters. As between overlying owners, the rights, like those of riparians, are correlative and are referred to as belonging to all in common; each may use only his reasonable share when water is insufficient to meet the needs of all. (Katz v. Walkinshaw, 141 Cal. 116 [70 P. 663, 74 P. 766, 99 Am.St.Rep. 35, 64 L.R.A. 236]; see 26 Cal.Jur. 269-273, 276; cf., 25 Cal.Jur. 1063-1067.) As between appropriators, however, the one first in time is the first in right, and a prior appropriator is entitled to all the water he needs, up to the amount that he has taken in the past, before a subsequent appropriator may take any. (City of San Bernardino v. City of Riverside, 186 Cal. 7, 26-28 [198 P. 784] ; cf., Civ. Code, § 1414.)
Prescriptive rights are not acquired by the taking of surplus or excess water, since no injunction may issue against the taking and the appropriator may take the surplus without giving compensation; however, both overlying owners and appropriators are entitled to the protection of the courts against any substantial infringement of their rights in water which they reasonably and beneficially need. (Peabody v. City of Vallejo, 2 Cal.2d 351, 368-369, 374 [40 P.2d 486].) Accordingly, an appropriative taking of water which is not surplus is wrongful and may ripen into a prescriptive right where the use is actual, open and notorious, hostile and adverse to the original owner, continuous and uninterrupted for the statutory period of five years, and under *927claim of right. (City of San Bernardino v. City of Riverside, 186 Cal. 7, 22-23 [198 P. 784]; Katz v. Walkinshaw, 141 Cal. 116, 135 [70 P. 663, 74 P. 766, 99 Am.St.Rep. 35, 64 L.R.A. 236]; 25 Cal.Jur. 1178, 1157-1158; 1 Cal.Jur. 585; 26 Cal.Jur. 278-279; cf., Wutchumna Water Co. v. Ragle, 148 Cal. 759, 764-765 [84 P. 162].) To perfect a claim based upon prescription there must, of course, be conduct which constitutes an actual invasion of the former owner’s rights so as to entitle him to bring an action. (City of Los Angeles v. City of Glendale, 23 Cal.2d 68, 79 [142 P.2d 289].) Appropriative and prescriptive rights to ground water, as well as the rights of an overlying owner, are subject to loss by adverse user. This is in accord with the rule announced in cases dealing with water in a surface stream. (See Yankee Jim’s Union Water Co. v. Crary, 25 Cal. 504, 508-509 [85 Am.Dec. 145]; Big Rock M. W. Co. v. Valyermo Ranch Co., 78 Cal.App. 266, 273 [248 P. 264]; Peabody v. City of Vallejo, 2 Cal.2d 351, 374 [40 P.2d 486]; Duckworth v. Watsonville etc. Co., 150 Cal. 520, 529-532 [89 P. 338]; Davis v. Gale, 32 Cal. 26, 35 [91 Am.Dec. 554] ; 3 Farnham, Waters and Water Rights [1904], § 680a, p. 2106; 1 Wiel, Water Rights [3d ed., 1911], § 580, pp. 625-626; 56 Am.Jur. 773.)
In the present case some of the parties, including owners of ranches, golf clubs, and cemeteries, have pumped water solely for use on their own land, and their rights at the outset were overlying. The principal takers of water, however, are public utility corporations and municipalities which have either exported water or have used it within the Western Unit for municipal purposes or for sale to the public, and their taking, when commenced, was entirely appropriative. (City of San Bernardino v. City of Riverside, 186 Cal. 7, 29 [198 P. 784]; Eden Township County Water Dist. v. Hayward, 218 Cal. 634, 640 [24 P.2d 492].) Appellant exports about three-fourths of the water produced by it to customers located outside the area, and it claims overlying rights as to the- other one-fourth which it takes. As to the exported water it is clear that its rights could not be overlying in character, but are either appropriative or prescriptive.
It follows from the foregoing that, if no prescriptive rights had been acquired, the rights of the overlying owners would be paramount, and the rights of the appropriators would depend on priority of acquisition under the rule that the first appropriator in time is the first in right. The latest in time of the appropriations would then be the first to be curtailed *928in limiting total production of the area to the safe yield. If such were the case, the overdraft could be eliminated simply by enjoining a part of the latest appropriations, since the record shows that there is ample water to satisfy the needs of all the overlying users and most of the appropriators, and appellant’s appropriative rights would depend primarily upon evidence of priority in time of acquisition.
The principal dispute between appellant and respondents, however, concerns whether any water rights in the Western Unit have become prescriptive and, if so, to what extent. Respondents assert that the rights of all the parties, including both overlying users and appropriators, have become mutually prescriptive against all the other parties and, accordingly, that all rights are of equal standing, with none prior or paramount. Appellant, on the other hand, contends that in reality no prescriptive rights have been acquired, and that there has been no actionable invasion or injury of the right of any party using water because each party has been able to take all the. water it needed and no party has in any manner prevented a taking of water by any other party. It would follow, under appellant’s theory, that not even an overlying owner could have obtained an injunction against a subsequent taking.
We must look, therefore, to see if the disputed elements for a prescriptive right are shown by the record. Most of the factors are covered by the stipulation in which all the parties, including appellant, joined, namely, that “all of the water taken by eáeh of the parties to this stipulation and agreement was, at the time it was taken, taken openly, notoriously, and under a claim of right, which claim of right was continuously and uninterruptedly asserted by it to be and was adverse to any and all claims of each and all of the other parties joining herein.” Two necessary elements are omitted: The length of the period over which the adverse user continued and the nature and extent of actual adverse user, if any.
The evidence clearly supports the finding which designates in terms of acre feet per year “the highest continuous production of water for beneficial use in any five (5) year period prior to the filing of the complaint by each of the parties in each of said units, as to which there has been no cessation of use by it during any subsequent continuous five (5) year period.”
The record shows that there has been an actual adverse user of water in the Western Unit. There was an inva*929sion, to some extent at least, of the rights of both overlying owners and appropriators commencing in the year 1913-1914, when the overdraft first occurred. Bach taking of water in excess of the safe yield, whether by subsequent appropriators or by increased use by prior appropriators, was wrongful and was an injury to the then existing owners of water rights, because the overdraft, from its very beginning, operated progressively to reduce the total available supply. Although no owner was immediately prevented from taking the water he needed, the report demonstrates that a continuation of the overdraft would eventually result in such a depletion of the supply stored in the underground basin that it would become inadequate. The injury thus did not involve an immediate disability to obtain water, but, rather, it consisted of the continual lowering of the level and gradual reducing of the total amount of stored water, the accumulated effect of which, after a period of years, would be to render the supply insufficient to meet the needs of the rightful owners.
The proper time to act in preserving the supply is when the overdraft commences, and the aid of the courts would come too late and be entirely inadequate if, as appellant seems to suggest, those who possess water rights could not commence legal proceedings until the supply was so greatly depleted that it actually became difficult or impossible to obtain water. Where the quantity withdrawn exceeds the average annual amount contributed by rainfall, it is manifest that the underground store will be gradually depleted and eventually exhausted, and, accordingly, in order to prevent such a catastrophe, it has been held proper to limit the total use by all consumers to an amount equal, as near as may be, to the average supply and to enjoin takings in such quantities or in such a manner as would destroy or endanger the underground source of water. (City of San Bernardino v. City of Riverside, 186 Cal. 7, 15-16 [198 P. 784]; Burr v. Maclay Rancho Water Co., 154 Cal. 428, 438 [98 P. 260].) There is, therefore, no merit to the contention that the owners of water rights were not injured by the additional appropriations made after all surplus waters were taken, and they clearly were entitled to obtain injunctive relief to terminate all takings in excess of the surplus as soon as it became apparent from the lowering of the well levels that the underground basin would be depleted if the excessive pumping were continued.
*930The lowering of the water table resulting from the overdraft was plainly observable in the wells of the parties, and the records of water levels in appellant’s own wells afford an excellent example of the yearly changes from about 1919 to 1937, when the complaint herein was filed. Using figures taken at about the same time each year to minimize the effect of seasonal variations, it appears that the surface of the water in appellant’s well No. 1 was at an elevation of 559 feet above sea level in August, 1920, as compared with 485 feet in August, 1937, amounting to a drop of 74 feet. Appellant’s well No. 4 was measured at the 570-foot level in August, 1920, and at 499 feet in September, 1937, a drop of 71 feet. Appellant’s well No. 5 was at 553.1 feet in August, 1928, and at 514 feet in August, 1937, a drop of 39.1 feet in the shorter period of nine years. Well No. 6 was at the 542-foot level in August, 1919, at 568.2 feet in November, 1924, and at 515 feet in August, 1937, a net drop of 27 feet. Appellant’s well No. 7 was at 565.2 feet in October, 1924, and at 484 feet in August, 1937, a drop of 81.2 feet. Well No. 8 has records only for 1937 and 1938, and there are no records for two other wells, Nos. 2 and 3, which appellant has apparently abandoned.
This evidence is clearly sufficient to justify charging appellant with notice that there was a deficiency rather than a surplus and that the appropriations causing the overdraft were invasions of the rights of overlying owners and prior appropriators. The. elements of prescription being present in the record, the statute of limitations ran against the original lawful holders of water rights to whatever extent their rights were' invaded.
It must next be determined whether the rights of all of the prior owners were invaded and whether all or only a part of the right of any particular owner was damaged. It has been established that the rights of appropriators as well as of overlying owners will be protected by the courts and that an invasion of either type of right will start the running of the statute. Where, as here, subsequent appropriators reduce the available supply and their acts, if continued, will render it impossible for the holder of a prior right to pump in the future, there is an enjoinable invasion. In this respect there is no difference between an overlying owner and an appropriator. Although neither may prevent a taking of surplus waters, either may institute legal proceedings to safeguard the supply once a surplus ceases to exist and may *931enjoin any additional user beyond the point of safe yield.
Cases are cited for the proposition that an appropriator’s rights are not invaded if he continues to receive the quantity of water to which he is entitled. These cases, however, do not deal with the problem of gradual depletion of water stored in a basin or lake, but, rather, with surface streams or ditches in which water flows but is not retained for future use. The type of injury there considered would immediately deprive the owner of water, and the language in the opinions does not apply to an invasion of rights in a stored supply of water to be used only in future years. (See Faulkner v. Rondoni, 104 Cal. 140, 147 [37 P. 883] ; Peck v. Howard, 73 Cal.App.2d 308, 328 [167 P.2d 753]; City of San Diego v. Cuyamaca Water Co., 209 Cal. 105, 133 [287 P. 475].)
Neither the overlying owners nor the appropriators took steps to obtain the aid of the courts to protect their rights until the present action was instituted, many years after the commencement of the overdraft, and at first glance it would seem to follow that the parties who wrongfully appropriated water for a period of five years would acquire prior prescriptive rights to the full amount so taken. The running of the statute, however, can effectively be interrupted by self help on the part of the lawful owner of the property right involved. Unlike the situation with respect to a surface stream where a wrongful taking by an appropriator has the immediate effect of preventing the riparian owner from receiving water in the amount taken by the wrongdoer, the owners of water rights in the present case were not immediately prevented from taking water, and they in fact continued to pump whatever they needed. As we have seen, the Raymond Basin Area is similar to a large lake or reservoir, and water would be available until exhaustion of the supply. The owners were injured only with respect to their rights to continue to pump at some future date. The invasion was thus only a partial one, since it did not completely oust the original owners of water rights, and for the entire period both the original owners and the wrongdoers continued to pump all the water they needed.
The pumping by each group, however, actually interfered with the other group in that it produced an overdraft which would operate to make it impossible for all to continue at the same rate in the future. If the original owners of water rights had been -ousted completely or had failed to pump for a five-year period, then there would have been no interference *932whatsoever on the part of the owners with the use by the wrongdoers, and the wrongdoers would have perfected prior prescriptive rights to the full amount which they pumped. As we have seen, however, such was not the case, and, although the pumping of each party to this action continued without interruption, it necessarily interfered with the future possibility of pumping by each of the other parties by lowering the water level. The original owners by their own acts, although not by judicial assistance, thus retained or acquired a right to continue to take some water in the future. The wrongdoers also acquired prescriptive rights to continue to take water, but their rights were limited to the extent that the original owners retained or acquired rights by their pumping.
A partial analogy may be found in Smith v. Hampshire, 4 Cal.App. 8 [87 P. 224], where the appellant had constructed a ditch across the respondents ’ land and used it adversely for 10 years, but the respondents, for six years, had used a portion of the ditch jointly with but adversely to appellant. It was held that both had acquired rights in the ditch and that respondents’ acts, being hostile to appellant’s asserted claim of exclusive right, operated to conserve respondents’ right to use the ditch. The court said (p. 11): “While respondents could not acquire a prescriptive right to a right of way over their own land, they could destroy appellant’s claim of exclusive right by open, peaceable, notorious and continuous adverse use, and thus establish their right (as against his asserted, exclusive claim) to use the ditch themselves for a limited purpose and commingle their water with his in so doing. ’ ’
We need not determine whether the overlying owners involved here retained simply a part of their original overlying rights or whether they obtained new prescriptive rights to use water. (See Glatts v. Henson, 31 Cal.2d 368, 371 [188 P.2d 745].) The question might become important in order to ascertain the rights of the parties in the event of possible future contingencies, but these may never happen.
Adoption of appellant’s position that the water must be allocated, at least as between the municipalities and public utility companies, strictly on the basis of priority in time of appropriation would not only ignore the fundamental principle that the statute of limitations runs against persons who fail to act when their rights are invaded, but it would result in an unequal sharing of the burden of curtailing the *933overdraft in that all pumping conducted under authority of certain of the later appropriations would be completely eliminated, whereas no restriction in amount would be imposed upon pumping based on earlier appropriations. Such a result does not appear to be justified where all of the parties have been producing water from the underground basin for many years, and none of them have acted to protect the supply or prevent invasion of their rights until this proceeding was instituted. Moreover, it seems probable that the solution adopted by the trial court will promote the best interests of the public, because a pro tanto reduction of the amount of water devoted to each present use would normally be less disruptive than total elimination of some of the uses.
We hold, therefore, that prescriptive rights were established by appropriations made in the Western Unit subsequent to the commencement of the overdraft, that such rights were acquired against both overlying owners and prior appropriators, that the overlying owners and prior appropriators also obtained, or preserved, rights by reason of the water which they pumped, and that the trial court properly concluded that the production of water in the unit should be limited by a proportionate reduction in the amount which each party had taken throughout the statutory period.
Otheb Contentions
The water allowed each party by the trial court was measured by the amount taken over a five-year period as to which there had been no cessation of use during any subsequent five-year period. Appellant argues that, in determining whether there had been a loss of rights, the court should have applied the shorter three-year limitation prescribed by section 20a of the Water Commission Act, which was in effect prior to 1943. (Deering’s Gen. Laws (1937), Act 9091, § 20a, now Wat. Code, § 1241.) This section provided: “When the party entitled to the use of water fails to beneficially use all or any part of the water claimed by him, for which a right of use has vested, for the purpose for which it was appropriated or adjudicated, for a period of three years, such unused water shall revert to the public and shall be regarded as unappropriated public water.” This section, however, is not applicable here. The primary purpose of the act was to create a system for issuing licenses and permits for appropriation of surplus water (see Deering’s Gen. Laws (1937), Act 9091, §§ 1, Id, 11, 15, 16), and it is *934reasonably clear that section 20a was intended to refer only to water which had been appropriated under such a license or permit. Water in an underground basin is not embraced by the licensing system, because section 42 of the act provides that the term “water,” as used in sections of the act relating to permits or licenses, “shall be interpreted to refer only to surface water, and to subterranean streams flowing through known and definite channels.” (Deering’s Gen. Laws (1937), Act 9091, §42.) There is no claim that any of the rights to water involved in the present case were obtained under such a permit or license, and the ground water in the Raymond Basin Area does not flow in known and definite channels within the meaning of section 42.
In 1934, less than four years before the commencement of this action, the city of Pasadena began to take a quantity of water from the San Gabriel River, which is not a source of supply to the Raymond Basin Area. This diversion was terminated in 1941 as part of the settlement of litigation brought by users of water from the river. Appellant contends that when the city imported water from the San Gabriel River, it reduced the amount which it took from the underground basin and, therefore, that it is now barred by estoppel and laches from taking out of the basin more water than the maximum amount pumped during the period in which it used water from the river. The trial court found, however, that appellant was not induced to take any action by reason of the importation and that the city was not estopped. The finding is supported by the record and, accordingly, is conclusive on this appeal. The claim of laches is sufficiently answered by the failure to show prejudice and the fact that the time involved was less than five years prior to commencement of the action.
There is no merit to the assertion that, because of considerations of public policy, the city of Pasadena should be compelled to purchase some of its water from the Metropolitan Water District of Southern California instead of exercising its right to take water from the underground basin. Although the city has the right to purchase water from the district, it does not follow that the city should be compelled to do so in order to afford a larger supply to other parties.
The failure of the city of Pasadena to capture and return to the underground basin storm waters and waters used to flush streets, fight fires, and flow sewage does not, as claimed by appellant, constitute waste in violation of sec*935tion 3 of article XIV of the California Constitution. Storm drains used for flood control carried some water outside the area, but this does not mean it was wasted, and there is no evidence that there was any waste in connection with the use of water in ordinary and necessary municipal activities.
A water exchange agreement, enforced by the judgment but not signed by appellant, provided that the city of Pasadena should restrict its pumping in the Monk Hill Basin and take the remainder of its share of water from elsewhere in the Western Unit. Appellant cannot properly complain of this provision unless it is injured thereby, and it could not be damaged unless the city pumped water in such quantities in the immediate vicinity of appellant’s wells as to render it difficult or impossible for appellant to obtain the amount of water to which it is entitled. No reasonable likelihood of such an occurrence is shown, but, in the event that such a local shortage should take place, appellant may obtain relief under that portion of the judgment reserving jurisdiction to make such modifications as may become necessary.
It is next argued that the injunction should not have limited appellant to a fixed number of acre feet of water a year but, rather, that unrestricted pumping should be allowed so long as the water in the wells is above some specified level. Although this might be a proper method of safeguarding the supply of water in the underground basin, there is nothing in the record which compels a finding that the method of conservation adopted by the trial court is improper or that it would result in an undue raising of the water table. Moreover, ample protection against such a danger is afforded by the provisions of the decree reserving jurisdiction in the trial court to modify the judgment and requiring the water master to keep monthly recordings of the depth of water in all wells.
The court did not err in refusing to admit evidence offered to rebut the report of the referee with respect to appellant’s water production from 1931 to the end of 1938. Section 24 of the Water Commission Act provides that “ [N]o exception shall be considered except in the court’s discretion, or for some good cause shown, unless it shall appear that the matter of the exception had theretofore been presented to the commission in the form of an objection.” (Cf., Wat. Code, §§ 2017-2019.) Appellant did not comply with this requirement and showed no good reason why it did not do so.
*936All parties except appellant stipulated that each of them who had diverted water from streams leading to the underground basin should be restricted to an amount measured by the maximum capacity of its diversion works “as the same existed at any time within five (5) years prior to October 1, 1937,” which was approximately one week after commencement of the action. Pursuant to this stipulation the court concluded that each of these diverters had the right to take this amount as against all parties other than appellant, but enjoined any increase in the amount to be taken and expressly stated that it was making no determination as to the existence of such rights as against appellant. It is argued that, before any injunction was issued, the court should have determined appellant’s rights as against the parties diverting from streams leading to the underground basin. The issue, however, was not clearly raised in the pleadings, and there was not sufficient evidence in the record to enable the court to make a determination as to the priority of rights or as to the effect of these diversions upon the safe yield in the basin. In view of the necessity of securing a present solution for the critical situation in the basin area, the court was justified in leaving open for future determination the rights of appellant as against all such diversioners, some of whom were not made parties to the action.
The court reserved jurisdiction, among other things, to review its determination of the safe yield of the Eaymond Basin Area and the rights of all the parties as affected by the abandonment or forfeiture of any right. The reservation specifies that “in the event material change be found or any such abandonment or forfeiture be established” the court can ‘ adjudicate that the decreed right of each party to pump or otherwise take water from the ground in the Eaymond Basin Area shall be changed proportionately in the same manner as originally fixed herein. ...” Beview of the safe yield was to be had “not more frequently than at five (5) year intervals.” Appellant concedes that the court would have power to retain jurisdiction to readjust the rights of the parties in accordance with the law and the facts as they may be at the time, but it asserts that the court went beyond its authority and decreed as to rights which may be attained in the future insofar as it reserved jurisdiction to pass upon abandoned or forfeited waters and provided that the right of each party should be altered proportionately in the event of any material change or abandonment. The five-year limi*937tation upon redetermination of the safe yield is also challenged by appellant.
The retention of jurisdiction to meet future problems and changing conditions is recognized as an appropriate method of carrying out the policy of the state to utilize all water available. (Allen v. California Water & Tel. Co., 29 Cal.2d 466, 488 [176 P.2d 8]; City of Los Angeles v. City of Glendale, 23 Cal.2d 68, 81 [142 P.2d 289].)
In the present case, the trial court concluded that each party owned “by prescription” its “present unadjusted right,” that is, the amount which it had been actually pumping. The effect of the judgment is to decree that, while the parties have this present right, it is necessary, in order to conserve the basin and preserve the rights of all parties, to limit the takings to the amount of the safe yield and therefore to make a pro tanto or proportionate reduction in the amount which each can be permitted to pump until such time as conditions warrant an increase. This solution of the problem recognizes that the original owners have some rights to continue to pump in the future, that at the same time certain prescriptive rights have ripened on the basis of appropriations made after the overdraft commenced, and that the rights of each of the parties are measured by the amounts of the respective takings. Under such circumstances, it is proper to provide that, if the amount of the safe yield is increased, the permissible taldngs shall be increased proportionately up to the amount of the “present unadjusted right” of each party. The adjudication thus applies to existing rights, and there is no declaration as to future rights in water to which a party has no present right. Accordingly, the action of the court is not in conflict with the statement in City of San Bernardino v. City of Riverside, 186 Cal. 7 at pages 30-31 [198 P. 784], to the effect that a court should not undertake to make a declaration as to future rights.
We are of the opinion, however, that the five-year limitation upon the power to review the determination of safe yield tends to defeat the purpose of the rule giving the trial court continual supervisory powers in water rights cases, and that the judgment should be modified to preserve a broad retention of jurisdiction in the trial court to change its decree and orders, after notice and hearing, as the occasion may require. Paragraph XXI of the judgment is, therefore, modified by striking therefrom the following provision: “and that the review of its determination of the safe yield of either *938or both of said units of the Raymond Basin Area shall be had not more frequently than at. five (5) year intervals after the date hereof.”
As so modified, the judgment is affirmed, respondents to recover costs on appeal.
Shenk, J., Edmonds, J., Traynor, J., and Spence, J., concurred.
In accordance with the terminology employed by the trial court and the parties, the expression ‘‘ground water” will be used to refer to water beneath the surface of the ground.
Compare Water Code, sections 22, §000, g00t.