concurring.
While concurring in the majority opinion, I write separately to further clarify the import of Rutledge v. State, 94 Idaho 121, 482 P.2d 515 (1971), and to more specifically address the issue on appeal.
As the district court, in its memorandum decision, explained: “For the purposes of this [summary judgment] motion, the Plaintiff [Idaho Forest Industries] does not dis*520pute the fact that at least some portion of the twenty-nine acres in dispute was lake-bed prior to the building of the dike in 1909.” The district court further observed: “Since it is not disputed that, prior to the construction of the dike, at least a portion of the disputed real property was below the natural high water mark of Hayden Lake, it is clear that title to such part of the property was held by the State for the use and benefit of the people.”1 The district court then succinctly framed the question before it and summarized its answer:
The primary question involved in resolving the dispute between the Plaintiff and the State of Idaho is whether or not the construction of the dike, which altered the natural shoreline of the lake, coupled with the passage of time, has resulted in the loss of such title by means of the doctrine of adverse possession. Overriding all other issues, of course, is the question of whether or not there are material facts in dispute which would preclude the granting of summary judgment.
The record in this case clearly establishes that there are no material issues of fact in dispute with respect to the question of whether or not the State can be subject to the doctrine of adverse possession as such doctrine pertains to the facts established in this case by such record. (Emphasis added).
The state appeals from this conclusion that riparian land owners can dike or otherwise drain and fill state lands held in trust, and subsequently obtain title to those lands by means of adverse possession.
Private concerns acting without the state’s authority clearly cannot drain away navigable waters in order to adversely possess lands impressed with the trust. The California court long ago correctly held as follows:
Where the accretions have resulted, not from natural causes, but from artificial means, such as the erection of a structure below the line of ordinary high water, there is made out a case of purpresture, or encroachment, and the deposit of alluvion caused by such structure does not inure to the benefit of the littoral or upland owner, but the right to recover possession thereof is in the state or its successor in interest, as the case may be. City of Los Angeles v. Anderson, 206 Cal. 662, 275 P. 789, 791 (Cal.1929).
The California court further held that trust lands thus artificially encroached upon “cannot be gained by adverse possession____” Id. Overwhelming authority is in agreement. California ex. rel. State Lands Commission v. United States, 457 U.S. 273, 102 S.Ct. 2432, 2435, 73 L.Ed.2d 1 (1982); City of Long Beach v. Mansell, 3 Cal.3d 462, 91 Cal.Rptr. 23, 28 n. 4, 476 P.2d 423, 428 n. 4 (1970) (both cases citing City of Los Angeles v. Anderson as controlling); State v. Sause, 217 Or. 52, 342 P.2d 803, 826 (1959); see generally Annotation, Acquisition by Adverse Possession or use of Public Property Held by Municipal Corporations or Other Governmental Unit Otherwise than for Streets, Alleys, Parks, or Common, 55 A.L.R.2d 554, §§ 15, 16 (original and later case service volumes).
Rutledge is not to the contrary. As revealed in the Rutledge record, the litigants’ alternative theories to explain the change in the Boise River’s course were a sudden avulsion versus a gradual accretion and reliction. Plaintiff Rutledge, the riparian landowner, advanced the latter explanation. The State contended that the river’s course changed avulsively in 1878 through high flow flooding. Although there was some evidence at the district court level of human alterations along the river which may have influenced its course, these alterations were not carried out by Rutledge, were not directly associated with the area at issue, and were attributed only incidental significance. In fact, on appeal, the State’s brief made no mention of any possi*521ble human influences, but rather relied entirely on its theory that the river had changed avulsively and its argument that such a change should not influence its property interests. Consequently, Rutledge only decided that where a river changes course, whether avulsively or through accretion and reliction, and without the riparian owner contributing to the change, leaving the former river bed completely dry and above the new high water mark, then the former river bed is subject to adverse possession.
In contrast, the instant case apparently involves the construction of a dike for the express purpose of holding back the waters of Hayden Lake. Such filled or otherwise drained trust land must remain impressed with the public trust and not subject to adverse possession. City of Los Angeles v. Anderson, supra; State v. Sause, supra; Annotation, supra, 55 A.L.R.2d 554, §§ 15 and 16. Cf. City of Berkeley v. Superior Court, 26 Cal.3d 515, 162 Cal.Rptr. 327, 339, 606 P.2d 362, 374 (1980) (though not in the instant circumstances, “some reclaimed land might be eminently useful for trust purposes____”); Opinion of the Justices, 383 Mass. 895, 424 N.E.2d 1092, 1103 (1981) (“As to lawfully filled [formerly] submerged land, appropriate consideration must be given to the identity of the land, the nature of the Commonwealth’s (and the public’s) continuing interest, if any, in that land, and the use to which the land is or may be put.”) If they were subject to adverse possession, the state would be left vulnerable to surreptitious drain and fill operations which would destroy important wetlands and rob Idahoans of the associated resources and values. Because of the important policy interests associated with trust lands, this Court has held them immune from adverse possession. Ehco Ranch, Inc. v. State ex. rel. Evans, 107 Idaho 808, 812, 692 P.2d 454, 459 (1984); Rutledge, supra; accord, e.g., City of Los Angeles v. Anderson, supra.
If we held otherwise, adverse claimants could accomplish by wrongful, unilateral action what the state itself could not accomplish by voluntary conveyance, namely the alienation of public trust land for purely private purposes. The state may convey public trust lands only where the conveyance serves public trust interests. This Court has stressed that the state must carefully weigh competing trust interests prior to alienation. The conveyance generally remains subject to the public trust even after title has passed. See Kootenai Environmental Alliance, supra. Adverse possession would defeat all of these public interest protections. Former trust lands are not subject to adverse possession by means of drain and fill, diking, or other operations carried out by riparian owners to remove the waters from the lands.
As Justice Bakes observes, the case must be remanded to the district court for resolution of factual disputes. It remains unclear whether the area at issue is yet submerged under navigable waters due to periodic flooding, and whether and to what extent the area ever was below the high water mark and thus impressed with the public trust. However, it is important that we address the issue on appeal to establish the correct legal background for the district court to properly conclude the case.
DONALDSON and BISTLINE, JJ., concur.. Justice Bakes correctly notes that IFI concedes this only for the purposes of its summary judgment motion.