This entire controversy revolves around a construction and interpretation of §§ 42-605 and 42-607, Idaho Code, as amended, which grant to the watermaster of a water district certain powers and duties in connection with the distribution of waters from public streams in his district. The factual background is undisputed as shown by the affidavits filed with the court in connection with the plaintiff-respondent’s motion for summary judgment which was granted by the trial court. This appeal is taken by the defendants-appellants from that order granting the motion for summary judgment.
The plaintiff-respondent, C. V. DeRousse, claims a water right by constitutional appropriation under Section 3 of Article 15 of the Idaho Constitution in the waters of Thorne Creek. Water district 12-A encompasses Thorne Creek which is a tributary of Mores Creek which in turn is a tributary of the Boise River. There have been prior water decrees adjudicating water rights on these waters of which the primary one is commonly known as the "Stewart Decree,” Farmers Cooperative Co. v. Riverside Irrigation District, et al., Seventh Judicial District, Canyon County, filed January 20, 1906. Neither party contends that the plaintiff is precluded from asserting his water right by reason of the decree as apparently neither the plaintiff nor his predecessors were made parties to the action.
In the summer of 1968 the defendants determined that there was a scarcity of water in the Boise River to the extent that it was insufficient to satisfy the rights of persons having adjudicated rights under the “Stewart Decree” so that the defendants shut off plaintiff’s diversion of water from Thorne Creek and gave him written notice to the effect that any interference with this action could lead to criminal prosecution. In taking such action, the defendants were acting under § 42-607, Idaho Code, as it then existed, to wit:
"Distribution of water. — It shall be the duty of said watermaster to distribute the waters of the public stream, streams or water supply, comprising his water district, among the several ditches taking water therefrom according to the prior rights of each respectively, in whole or in part, and to shut and fasten, or cause to be shut or fastened, under the direction of the department of reclamation, the headgates of the ditches heading from such stream, streams or water supply, *175when in times of scarcity of water it is necessary so to do in order to supply the prior rights of others in such stream, or water supply: provided, that any person or corporation claiming the right to the use of the waters of the stream or water supply comprising a water district, but not owning or having the use of an adjudicated right therein, shall, for the purposes of distribution, during the scarcity of water, be held to have a right subsequent to the adjudicated rights in such stream or water supply, and the water-master shall close all headgates of ditches having no adjudicated right if necessary to supply adjudicated rights in such stream or water supply, provided that any water right, the priority of which has been decreed, shall be deemed to be adjudicated within the meaning of this section.” (Emphasis added).
Based upon these facts the plaintiff De-Rousse filed suit against the defendants alleging the basic facts including the interference with the claimed constitutional water right of plaintiff, prayed for a declaratory judgment interpreting § 42-607 and an injunction against the defendants from interfering with plaintiff’s diversion of water from Thorne Creek. Thereafter the plaintiff filed a motion for summary judgment together with supporting affidavits.
While this first motion was pending, the legislature amended § 42-607 and § 42-605, Idaho Code, as set forth in Chapter 305 of the 1969 Session Laws. Section 42-607, Idaho Code, quoted above, was amended to read as follows:
“Distribution of water. — It shall be the duty of said watermaster to distribute the waters of the public stream, streams or water supply, comprising his water district, among the several ditches taking water therefrom according to the prior rights of each respectively, in whole or in part, and to shut and fasten, or cause to be shut and fastened, under the direction of the department of reclamation, the headgates of the ditches heading from such stream, streams or water supply, when in times of scarcity of water it is necessary so to do in order to supply the prior rights of others in such stream, or water supply-r provided; that any pcr-soa or eoFporation claiming the Fight te the ase ef the waters ef the stream or water supply comprising a water- district; feat aet owning or having the ase ef an ad■J U.Q1 titLtítC TTCXXl! t'XX“X Vifi'iJ TlTtCXXj TOT ttiC jJTll ■poses of distribution; during the scarcity of water; fee held te have a -right subsequent to the adjudicated rights in each stream of water- supply; and the water-master shall dose ell headgates ef ditehes haring no adjudicated right if necessary te supply adjudicated rights in such stream er water supply; provided that any water right; the priority of which has ■been decreed; shall fee deemed te fee adjudicated within the meaning ef this section SO LONG AS A DULY ELECTED WATERMASTER IS CHARGED WITH THE ADMINISTRATION OF THE WATERS WITHIN A WATER DISTRICT, NO WATER USER WITHIN SUCH DISTRICT CAN ADVERSELY POSSESS THE RIGHT OF ANY OTHER WATER USER.”
In addition, § 42-605 was amended in part to add the following definition:
“ . . . for the purposes of this chapter, a ‘right’ shall mean any water right which has been adjudicated by the court or is represented by valid permit or license issued by the department of reclamation.”
As a result of the amendments concerning the powers of a watermaster, the plaintiff DeRousse amended his complaint alleging the new law and again praying for a declaratory judgment interpreting the statute, and for an injunction against the defendant from interfering with his claimed constitutional' water right. Both parties acknowledge that § 42-607, Idaho Code, before the 1969 amendment instructed the watermaster to give adjudicated water rights a complete preference over unadjudicated water rights in times of water scar*176city to the extent of closing all headgates of ditches of unadjudicated water rights if necessary to supply sufficient water for the adjudicated rights. See Big Wood Canal Co. v. Chapman, 45 Idaho 380, at 405, 263 P. 45 (1927).
The plaintiff now contends that as a result of the 1969 amendment this instruction to the watermaster was expressly stricken and withdrawn so that under the statute itself the watermaster has no jurisdiction or control over unadjudicated water rights claimed to have been appropriated in the constitutional method by diversion and appropriation to beneficial use. On the other hand the defendants contend that the 1969 amendment to §§ 42-607 and 42-605, Idaho Code, preserved the defendants’ legal authority to shut off plaintiff’s diversion of water from Thorne Creek so long as his rights to the use of said waters are not represented by a court’s decree or by a permit or license issued by the Idaho Department of Reclamation. In essence, the trial court held that the Idaho statutes as constituted after the 1969 amendment left the defendants without any jurisdiction or control over unadjudicated water rights within the district not represented by a permit or license. By reason thereof the trial court entered a permanent injunction prohibiting the defendants from shutting off plaintiff’s diversion of water under §§ 42-605 and 42-607, Idaho Code, as presently constituted.
The question before the court, therefore, is an interpretation of the 1969 amendment to the above quoted statutes. We first concur with the parties to the action that prior to the 1969 amendment, § 42-607, Idaho Code, purported to grant to the watermaster the right to shut off unadjudicated water rights within the district during the time of water scarcity and give preference to all adjudicated water rights on the stream. See Big Wood Canal Co. v. Chapman, supra. The relevant language purporting to grant this power was stricken and removed from this statute by the 1969 amendment.
It has long been held by this court that when a statute is amended by the legislature a presumption arises that a change in application of the statute was intended. Anderson v. Rayner, 60 Idaho 706, 713, 96 P.2d 244 (1939). “When a statute is amended, it is presumed that the legislature intended it to have a meaning different than that accorded to it before the amendment.” Wellard v. Marcum, 82 Idaho 232, 239, 351 P.2d 482 (1960). See Employment Security Agency v. Joint Class “A” School District No. 151, 88 Idaho 384, 391, 400 P.2d 377 (1965).
Therefore, inasmuch as substantial changes were made in §§ 42-607 and 42-605, Idaho Code, we must presume that the legislature intended for the statutes to have a different meaning from that accorded to them before the amendment. In making such a statutory interpretation or construction, it is a “. . . universal rule of statutory construction that a statute must be construed in the light of its intent and purpose.” Jorstad v. City of Lewiston, 93 Idaho 122, 125, 456 P.2d 766, 769 (1969).
“The primary function of the appellate court in construing a statute is to ascertain the legislative intent and give effect thereto. Knight v. Employment Security Agency, 88 Idaho 262, 398 P.2d 643 (1965) ; Messenger v. Burns, 86 Idaho 26, 382 P.2d 913 (1963) ; Lebrecht v. Union Indemnity Co., 53 Idaho 228, 22 P.2d 1066, 89 A.L.R. 640 (1933).'” Idaho Public Utilities Commission v. VI Oil Co., 90 Idaho 415, 420, 412 P.2d 581, 583 (1966).
Furthermore, if possible, it is incumbent upon a court to give a statute an interpretation which will not in effect nullify it. Filer Mutual Telephone Co. v. Idaho State Tax Commission, 76 Idaho 256, 261, 281 P. 2d 478 (1955).
“We adhere to the cardinal rules of construction which require that courts should not nullify a statute or deprive a law of potency and force unless such course is absolutely necessary; meaning and effect should be given to every section of a code *177in all its parts, if possible to do so.” Sampson v. Layton, 86 Idaho 453, 457, 387 P.2d 883 (1963).
With the foregoing principles of statutory construction in mind we now address ourselves to the problem of determining the meaning of § 42-607, Idaho Code, as amended by Chapter 305 in the 1969 Session Laws.
Section 42-607 was enacted by House Bill 146, Section 26, 1903 Idaho Session Laws. As originally enacted it read in pertinent part as follows:
“Sec. 26. It shall be the duty of said water master to divide the water in the natural stream or streams of his district among the several ditches taking water therefrom according to the prior rights of each respectively in whole or in part and to shut and fasten, or cause to be shut and fastened, under the direction of the water commissioner of his water district the head gates of ditches heading in any of the natural streams of the district, when, in times of scarcity of water, it is necessary so to do by reason of priority of rights of others taking water from the same stream, or its tributaries.”
In 1909 the section was amended by House Bill 68, adding among other things the following proviso:
“. . . Provided, That any person or corporation claiming the right to the use of the waters of the stream or water supply comprising a water district, but not owning or having the use of an adjudicated right therein, shall, for the purpose of distribution, during the scarcity of water, be held to have a right subsequent to the adjudicated rights in such stream or water supply, and the water master shall close all headgates of ditches having no adjudicated right if necessary to supply adjudicated rights in such stream or water supply.” H.B. 68, 1909 Session Laws, p. 326, at 329.
The section then remained substantially the same with certain minor changes until this suit was filed by the plaintiff-respondent. Shortly thereafter, Chapter 305 of the 1969 Session Laws was enacted which in essence struck the proviso which had been added in 1909. Additionally, Chapter 305 of the 1969 Session Laws amended 42-605 to define water “right” as any water right represented by a valid permit or license, or one which had been adjudicated by a court. Before the 1969 amendment, 42-607 was twice mentioned by this court as providing that the watermaster has the duty during the times of scarcity of water to treat unadjudicated water rights as inferior and subordinate to decreed rights. See Big Wood Canal Co. v. Chapman, 45 Idaho 380 at 405, 263 P. 45 (1927) ; State v. Hall, 90 Idaho 478 at 489, 413 P.2d 685 (1966). This is basically what the defendants did in the instant case by shutting off the diversion of water by the plaintiff on the ground that his right was unadjudicated and therefore inferior to adjudicated rights on Thorne Creek. The 1969 amendment, however, completely eliminates all reference in § 42-607 to unadjudicated water rights appropriated under the Idaho Constitution and expressly deletes the reference that such unadjudicated water rights in times of scarcity of water be shut off until all adjudicated water rights have been fulfilled. In other words, the preference of adjudicated water rights over unadjudicated water rights was deleted from the statute. As a result of the 1969 amendment, there is absolutely no reference to unadjudicated water rights in the powers, duties and instructions to the watermaster of a water district. We therefore find that the amendment shows a clear intention on the part of the legislature to eliminate any preference of adjudicated water rights over unadjudicated water rights in times of water scarcity and that the watermaster has no jurisdiction or control over unadjudicated water rights.
Defendants contend that the remaining language in I.C. § 42-607, as amended, taken together with the definition of “right” as added to I.C. § 42-605, shows the legislative intent to be that both adjudicated and permit or licensed water rights be granted priority over constitutional use rights, and that the watermaster has authority to shut *178off use rights during time of scarcity. That portion of I.C. § 42-607 giving the water-master his authority reads as follows:
“It shall be the duty of said watermaster to distribute the waters . . . among the several ditches . . . according to the prior rights . . . .”
Since, by definition in I.C. § 42-605, “rights” do not include constitutional use rights, the watermaster does not have authority to deal with such use rights, regardless of scarcity.
This conclusion is supported by the fact that § 42-605 was amended by adding the definition for the word “right” to state that it shall mean only adjudicated water rights or those held under a valid permit or license issued by the Department of Reclamation. In further examining Chapter 305 of the 1969 Session Laws it is to be noted that throughout § 42-605 all references to an “adjudicated right” were amended by Chapter 305 of the 1969 Session Laws by striking the word “adjudicated.” We therefore conclude that under Chapter 6 of Title 42 a watermaster has no jurisdiction or control over an unadjudicated water right. This is further substantiated by the fact that § 42-604, dealing with the creation of water districts, expressly provides that no water district can be created so as to apply to streams or water supplies which have not been adjudicated by a court of competent jurisdiction.
One further amendment was made to § 42-607 by adding the new phrase:
“. . . so long as a duly elected watermaster is charged with the administration of the waters within a water district, no water user within such district can adversely possess the right of any other water user.”
This portion of the amendment appears to be in part a statutory enactment of the doctrine pronounced in Big Wood Canal Co. v. Chapman, supra, in which it was held that one party could not obtain a prescriptive or adverse possession right against another in and to a water right which was being administered and distributed by a water-master. However, this doctrine announced by the court in that case was done in the same paragraph as the discussion of the right of priority of adjudicated water rights over unadjudicated water rights within a water district and the duty of the watermaster to grant a preference to the adjudicated rights. As the 1969 amendment withdrew any jurisdiction of the watermaster over unadjudicated constitutional water rights in the water district, the legislature apparently felt it was necessary to place this doctrine in statutory form as the watermaster would no longer have any control or jurisdiction over the unadjudicated rights.
We are not unmindful of the cogent reasons expressed on behalf of defendants for the adoption of a policy which would allow the watermaster to control all of the rights in a ditch including unadjudicated use rights. However, we must accept the policy set out by the legislature in the statute, as we view it, and if this policy is not in the best interests of irrigated agriculture in the state, or if we have misinterpreted the legislative policy, there will be ample opportunity for the next session of the legislature to make any necessary changes. In the meantime, since there is nothing to indicate there are other users on Thorne Creek who would be adversely affected by the diminished water supply as a result of plaintiff’s appropriation, there is much less injury to the Boise River water system as a whole as a result of allowing plaintiff to continue to divert his five inches of water than would be to plaintiff if he were totally prevented from using any water from Thorne Creek.
The trial court correctly held that §§ 42-605 and 42-607, Idaho Code, as presently constituted, do not give the defendants any legal authority over water rights not represented by a court decree or by a permit or license issued by the Idaho Department of Reclamation and that the defendant be permanently enjoined from shutting off plaintiff’s diversion of water from Thorne Creek pursuant to §§ 42-605 and 42-607, Idaho Code. Because of this disposi*179tion it is not necessary to discuss the constitutional and other contentions of the parties.
Accordingly, we affirm, with costs to respondent.
McQUADE, C. J., DONALDSON, J., and WARD, District Judge, concur.