Opinion
MOSK, J.In a series of recent cases, this court has considered the scope and effect of the public trust doctrine. Under that doctrine, the state holds a trust interest on behalf of the public in tidelands (City of Berkeley v. Superior Court (1980) 26 Cal.3d 515 [162 Cal.Rptr. 327, 606 P.2d 362]) and in lands between high and low water in non-tidal navigable lakes (State of California v. Superior Court (Lyon) (1981) 29 Cal.3d 210 [172 Cal.Rptr. 696, 625 P.2d 239]; State of California v. Superior Court (Fogerty) (1981) 29 Cal.3d 240 [172 Cal.Rptr. 713, 625 P.2d 256]). The public may use such properties for purposes such as commerce, navigation, and fishing, as well as for environmental and recreational purposes. These lands may be conveyed to private persons only to promote trust uses, and grants not made for that purpose remain subject to the rights of the public. (For a scholarly analysis of the development of the public trust in the United States and in California, see Stevens, The Public Trust (1980) 14 U.C. Davis L.Rev. 195, 199 et seq.)
The foregoing cases involved property which was originally owned in fee by the state or federal government and granted by them to private persons. In the present case, the issue is whether the public trust doctrine applies to tidelands in which the state and federal government never had fee title. The tidelands involved here were originally acquired by private persons from the Mexican government prior to the time California was ceded to the United States under the Treaty of Guadalupe Hidalgo, and later patented to the owners by the federal government in accordance with the requirements of the treaty.
Ballona Lagoon, the subject of this proceeding, is an arm of the Pacific Ocean in the Marina del Rey area of Los Angeles. It is subject to *292the tides, and inundated with seawater at mean low tide and mean high tide. At mean high tide, the depth of the water is sufficient to be navigable by shallow draft vehicles. At its northern end, the lagoon is connected to the Venice Canals, and provides the sole source of water for them.
In 1905, the shore surrounding the lagoon was subdivided into three large abutting tracts, and some of the tidelands were filled and improved. The present case involves two of those tracts, lot R of the Silver Strand subdivision and a portion of lot C of the Del Rey subdivision, both of which consist entirely of waterways. Access to the lagoon is now provided by walkways surrounding the shore, public streets to the shoreline, and bridges across the lagoon. In recent years, motor-controlled tide gates were installed between the Pacific Ocean and the entrance to the lagoon to control the ebb and flow of the tide within the lagoon; they are used to prevent flooding of the adjacent land.
The City of Los Angelas desired to dredge the lagoon, construct sea walls, and make other improvements therein without exercising its power of eminent domain. It filed an action for declaratory relief and to quiet title in the lagoon against the owners of lots C and R, and the holder of an easement in these lots (hereinafter called defendants).1 The complaint alleged that the public owns an easement in the lagoon for commerce, navigation andi fishing, for the passage of fresh water to the Venice Canals, and for water recreation. It alleged also that the lots had been dedicated by their owners for public use. The city joined the State of California as a defendant in the action, ás contemplated by *293section 6308 of the Public Resources Code.2 The state thereafter filed a cross-complaint, alleging that it had acquired an interest in the tidelands of the lagoon for commerce, navigation and fishing upon admission to the Union, that it held this interest in trust on behalf of the public, and had granted its interest to the city. (For literary convenience, the city and the state will be referred to collectively as plaintiffs.)
After a trial at which both documentary and testimonial evidence was received, the trial court determined that the state holds in trust for the people the easements claimed in the city’s complaint, and that the state or its successors have the right to construct the improvements in the lagoon without exercising the power of eminent domain.3 The court found also that defendants had dedicated the property as public streets or waterways.
Before discussing the primary issue of whether the tidelands trust applies to lands granted by Mexico and later patented to the owners by the federal government, we must consider defendants’ claim that the trust doctrine does not apply to their property. They assert that the United States government determined as a fact in the course of the proceedings which culminated in the issuance of a patent to their predecessors in interest that the property in question was not tidelands, and this determination, right or wrong, cannot now be challenged by plaintiffs.
In order to decide this issue, we must examine the circumstances of the original grant and the subsequent patenting process.
*294In 1839, while California was a part of Mexico, the Constitutional Governor of California granted to Augustin and Ignacio Machado and Filipe and Tomas Talamantes a property known as Rancho Ballona. The rancho’s western border was the Pacific Ocean, and it included lots C and R. After the war with Mexico was concluded by the Treaty of Guadalupe Hidalgo, California was ceded to the United States. Under the terms of the treaty, the rights of Mexican citizens to their property were to be “inviolably respected.” (Treaty of Guadalupe Hidalgo, Feb. 2, 1848, Art. VIII, 3 West’s Cal. Const. (1954) 727, 732.)
In keeping with this obligation, in 1851 the federal government passed “An Act to ascertain and settle the private Land Claims in the State of California” (hereinafter referred to as the Act of 1851), the purpose being to establish a method by which the claims to land granted by Mexico could be confirmed and settled in the grantees by the federal government. (9 Stat. 631.)
The Machados and Talamantes, following the procedure set forth in the act, petitioned the Board of Land Commissioners in 1852 for a decree confirming their title, to the rancho. After a hearing, the board confirmed the title, describing the boundaries of the rancho in the same terms as the original Mexican grant. That decision was affirmed by the United States District Court in 1855.
However, before a patent could issue, a survey of the property was required, approved by the purveyor General of California. (9 Stat. 633, § 13.) In 1858, Henry Hancock conducted a survey and prepared a plat which showed a large body of water labelled “inner bay” extending from the southwest corner of the property parallel to the Pacific Ocean in a northwesterly directidn. Hancock’s field notes set forth his measurements as he walked along the shores of the bay, crossed an inlet, and came to the Pacific Opean.
For reasons which are not. entirely clear from the record, the correctness of the survey was not determined until 17 years later. In 1869, objections to the survey were filed by owners of the ranch which bordered Rancho Ballona on the north, an area some distance from that marked “inner bay” on thp Hancock survey. Under a statute passed in 1864 to expedite the settlement of land titles in California (13 Stat. 332), the Hancock survey was forwarded to Washington to the General Land Office Commissioner; who was required to approve it prior to the issuance of the patent, and to settle conflicting claims to the lands sur*295veyed. Commissioner Willis Drummond decided that the survey was accurate with regard to the disputed northern boundary. He determined also that the “inner bay” shown on Hancock’s map was not an arm of the sea, basing this determination in part on three affidavits which stated that the area labelled “inner bay” on the plat was dry land used for pasturage, except at times of overflow at high water and during storms, when sand blocked the mouth of a creek which, on Hancock’s plat, emptied into the “inner bay.” However, Drummond approved the Hancock survey.
Thereafter, a patent was issued. It not only incorporated the plat prepared by Hancock, but his field notes as well. The grant was for “the tract of land embraced and described in the . .. Survey.... ” Defendants base their claim that the patent proceedings determined conclusively that the “inner bay” was not tidelands, upon the finding of Drummond.
The parties are in disagreement as to what was finally decided in the patent proceeding4 and whether the determination as to the character of the “inner bay” was necessary to the approval of the survey.5 For the purpose of analyzing the effect of the patent we assume, without deciding, that defendants prevail on these matters and that Drummond’s determination that the “inner bay” was not an arm of the sea was a final decision on that question and a necessary predicate to the issuance of the patent.
But these assumptions do not end the matter. The four corners of the patent, when considered in light of Drummond’s finding, present an obvious ambiguity. The plat attached to the patent shows an “inner bay,” and Hancock’s field notes, repeated therein, describe his measurements around this bay. The principal definition of a “bay” is “an inlet of the *296sea, usually smaller than a gulf, but of the same general character. .. . ” (Webster’s New Internal. Dict. (2d ed. 1951) p. 234.) Drummond had the power to investigate the correctness of the survey or to order that a new one be made (13 Stat. 332, 333). Instead, he approved it without requiring any changes even though it was inconsistent with his determination regarding the character of the “inner bay.”
In view of this inconsistency between the terms of the patent and the opinion of Drummond, the trial court was justified in admitting evidence as to whether the area in question was an arm of the sea and tidelands at the time California was admitted to the Union in 1850. The court found as a fact that for more than 900 years the lagoon has been an arm of the sea, subject to the tides. This conclusion is supported by overwhelming evidence, and defendants do not seriously challenge its validity.6
We come, then, to the primary issue before us, i.e., whether defendants’ property is subject to the public trust. Under the Act of 1851, all land in California, including tidelands, which had belonged to Mexico and was not patented to private parties, became the property of the United States. (9 Stat. 631, § 13, p. 633.) The federal government held the interest in tidelands in trust for the future state, and when California was admitted to the Union, it succeeded to the rights of the United States as an incident of sovereignty. (City of Berkeley v. Superior Court, supra, 26 Cal.3d 515, 521.)
Defendants urge that the tidelands trust is an incident of title, that the federal government never acquired title to tidelands granted by Mexico to private parties and confirmed by patents issued by the United States, and that it follows, therefore, that the state, upon admission to the Union in 1850, could not succeed to an interest which the federal government never possessed.7 Plaintiffs concede that defendants have title to the tidelands, but they assert that the federal government *297acquired an interest in trust in such lands on behalf of the public when California was ceded by Mexico, that this interest did not pass with the patent issued to defendants’ predecessors, and that the state acquired it as an incident of sovereignty in 1850.
In analyzing these conflicting claims, we must decide, first, whether the title which defendants’ predecessors received from Mexico was subject to the rights of the public in the tidelands encompassed in the grant and, second, if so, whether the United States acquired these rights upon annexation of California.
The law of Mexico at the time of cession declared that the public had a right to the use of the tidelands; this right was similar to the common law public trust.8 In the grant of the Rancho Ballona to the Machados and Talamantes, it was provided that the grantees “may enclose it without prejudice to the traversing roads and servitudes.” An expert on the law of Mexico who testified on behalf of defendants stated that the purpose of this language was to preserve “the rights of the public ... in the conveyance of large tracts of land by the authorities.”9 Thus, when California was ceded by Mexico, the title of defendants’ predecessors was subject to the interests of the public in the tidelands included in the grant.
Next, we consider whether the United States acquired that interest upon annexation of California. There is little authority regarding this issue. As we have seen under section 13 of the Act of 1851, lands which *298had belonged to Mexico and were not patented by the federal government to private parties became the property of the United States. This provision does not state whether less than fee interests retained by Mexico in land conveyed by that government, such as the public interest in tidelands, also passed to the new government.
So far as we have been able to determine, only one case has addressed that question. Under Mexican law, a grant of land by the government did not include mineral rights. In Moore v. Smaw (1861) 17 Cal. 199, the court was called upon to decide, inter alla, whether the United States became the owner of the mineral rights in California lands granted by Mexico to private parties. It held that under the provisions of the Act of 1851, the mineral rights retained by the Mexican government were “by the cession passed, with all other property of Mexico within the limits of California, to the United States.” (17 Cal. at p. 217.)
The same reasoning should apply to tidelands. The interest of the Mexican government in these lands, like mineral rights, was “property of Mexico,” at the time of cession and therefore became the property of the United States. In view of the public’s strong interest in tidelands, the established doctrine that title in such lands in the hands of private persons is usually subject to the rights of the public, and the rule that statutes conveying tidelands should be interpreted if reasonably possible to avoid a destruction of the public use (People v. California Fish Co. (1913) 166 Cal. 576, 597 [138 P. 79]), we hold that under the Act of 1851, the federal government succeeded to Mexico’s right in the tidelands granted to defendants’ predecessors upon annexation of California.
We reject defendants’ assertion that the tidelands trust is inevitably an incident of fee title by the government. It is true, as they claim, that prior cases have described the trust in the context of tidelands which the government owns or owned at one time.10 However, these cases do not hold that title in the government is essential to the existence of the *299trust. So far as we are aware, this is the first case which has squarely presented that question.11
Thus far, we have decided that upon annexation of California, the federal government succeeded to the ownership of the public’s rights in the tidelands contained in ranchos which had been conveyed by Mexico. The next question is whether those rights were relinquished by issuance of the patents to the Mexican grantees. The major disagreement between the parties arises over the effect of the patent on the tidelands. Defendants insist that the failure of the United States to reserve the public’s right when it issued the patent to their predecessors bars plaintiffs from now asserting such rights. Plaintiffs counter — and the trial court found — that, while the questions of title and boundaries were conclusively decided upon issuance of the patent, whether the title was subject to the rights of the public was not an issue in the patent proceedings.
Although early cases of the United States Supreme Court relied upon by defendants declared that the deed granted by the United States pursuant to the Act of 1851 was a “quitclaim, or rather ... a conveyance of such interest as the United States possessed in the land,” (Beard v. Federy (1866) 70 U.S. (3 Wall.) 478, 491 [18 L.Ed. 88, 92]; Adam v. Norris (1880) 103 U.S. 591, 593 [26 L.Ed. 583, 584]), this view was later rejected by the high court. In Boquillas Cattle Co. v. Curtis (1909) 213 U.S. 339, 344 [53 L.Ed. 822, 825, 29 S.Ct. 493], it was held that a patent from the federal government was a “confirmation in a strict sense” of the interest received from Mexico. In the course of its opinion, the court observed, “It is not to be understood that when the United States executes a document on the footing of an earlier grant by a former sovereign it intends or purports to enlarge the grant.” (213 U.S. at p. 344 [53 L.Ed. at p. 825].)12
Moore v. Smaw, supra, 17 Cal. 199, decided many years before Boquillas, appears at first blush to support defendants’ assertion that any *300rights acquired by the federal government upon cession in lands conveyed by Mexico to private parties were granted by the patent. However, when the reasons for the holding of Moore are analyzed, its effect is to support the position of plaintiffs.
As we have seen, Moore held that under the Act of 1851, the United States acquired ownership of minerals in lands which had been conveyed by Mexico to private parties because under Mexican law that government retained the ownership of the minerals. The question facing the court in Moore was whether the patent of the federal government, which reserved no interesjt in the minerals, granted that interest to the landowners. The court concluded that the grant included the mineral rights. It reasoned that California did not succeed to the interests of Mexico upon statehood sipce ownership of mineral rights was not an incident of sovereignty. Therefore, the federal government held that interest in the same capacity as a private landowner and, since a grant of land by an individual! without reservation of mineral rights passed ownership of such rights to the grantee, the same rule should apply to conveyances of the government. The court went on to state that patents of the United States since the Revolution had uniformly been regarded as transferring all the interest which the government could possess in the soil, even when the grant was a confirmation of one made by a prior government.
Thus, although Moore held that the federal patent enlarged the property rights of Mexican, grantees, the reason for its conclusion was that mineral rights are not an incident of sovereignty and, therefore, a patent by the United States which failed to reserve that right conveyed fee title to the grantee. The clear implication of this holding is that if sovereign rights to property had been involved the court’s conclusion would have been otherwise. Ti4elands are not held by the government in its proprietary capacity; they are held in trust for the benefit of the public, may not be alienated at will, and unlike lands containing mines, when tidelands are conveyed into private hands they ordinarily remain subject to the public interest even though the grant is purportedly in fee. (See, e.g., Carver v. San Pedro, L.A. & S.L.R. Co. (S.D.Cal. 1906) 151 F. 334, 337; People v. California Fish Co., supra, 166 Cal. 576, 593.) In the absence of convincing authority to the contrary, therefore, we may not presume that the patent issued to defendants’ predecessors included the interest in the tidelands which the United States government had acquired from Mexico.
*301Defendants cite numerous cases which they claim stand for the proposition that the patents issued under the Act of 1851 passed all interests of the federal government to the grantee, and that the state did not acquire any interest in the tidelands included in Mexican grants as an incident of sovereignty upon admission to the Union. These authorities establish that a federal patent determined conclusively that the grantee had title to the land described therein, and that this interest prevailed over later claims of ownership by private parties or the government. (E.g., Knight v. U.S. Land Association (1891) 142 U.S. 161, 184 [35 L.Ed. 974, 982, 12 S.Ct. 258]; San Francisco v. LeRoy (1891) 138 U.S. 656, 670-671 [34 L.Ed. 1096, 1101, 11 S.Ct. 364]; Beard v. Federy, supra, 70 U.S. 478, 492 [18 L.Ed. 88, 92-93]; People v. San Francisco, supra, 75 Cal. 388, 398; Teschemacher v. Thompson (1861) 18 Cal. 11, 26.) Moreover, the fact that the land described in the patent included tidelands did not diminish its conclusive effect. (United States v. Coronado Beach Company (1921) 255 U.S. 472, 487-488 [65 L.Ed. 736, 741-742, 41 S.Ct. 378].)
Defendants rely heavily on the case last cited. In the Coronado Beach case, the United States desired to construct military facilities on an island in San Diego Bay, which included tidelands. The owner derived title from a Mexican grant, and the patent issued pursuant to the Act of 1851 included the tidelands within the boundaries described therein. The high court held that the owner of the island had title to the tidelands and the federal government was required to pay compensation for their taking. In the course of its opinion, the court determined that the question whether there was a grant of the tidelands and boundaries of the grant had been decided in the confirmation proceedings, that California never had title to the tidelands by virtue of its sovereignty because they had been included in the Mexican grant and confirmed in the patentees, and that the grantees’ title could not be collaterally attacked by the federal government.13
*302This case, like the others relied upon by defendants, involves the question whether the title or boundaries of patented lands originating in Mexican grants may be collaterally attacked. In the present case plaintiffs concede that defendants have title to lots C and R; they claim, as did the state in our prior tidelands decisions, that the title of the landowners is subject to the rights of the public.
One case cited by defendants, in addition to Moore, considered the question whether a right jin property other than title was included in a patent issued to a landowner who derived title from Mexico. In United States v. Title Ins. Co. (1924) 265 U.S. 472 [68 L.Ed. 1110, 44 S.Ct. 621], the court held that Indians who had the perpetual right to occupy certain lands under Mexican law, did not retain that right in lands patented to private parties under the Act of 1851 because of their failure to assert it in the patent I proceeding.14
We do not find this case to be convincing authority. The right to occupy land is a normal incident of title, and we have no quarrel with the proposition that private persons who failed to assert their right to occupancy in the patent proceedings may not thereafter claim that right. But the right to exclude the public from tidelands is not a normal incident of title. To the contrary, as we have seen, conveyance of such lands by the government does not ordinarily free them from the burden of the public trust even though no reservation is made in the deed for the preservation of the people’s interest.
It follows from what we have said that the federal government retained an interest in the tidelands in question when it issued the patent to defendants’ predecessors, and that this interest was acquired by California upon its admission to statehood.
Our conclusion is supported not only by authority, but by policy as well. According to amiciis curiae, California Land Title Association, most of the land along the Pacific Coast from San Diego to Sonoma is *303situated in former Mexican ranchos. We do not know how much of the tidelands contained in these ranchos was conveyed by Mexico to private parties. If these areas of tidelands are free of the public interest, there is no right in the federal government, the state, or its successors, to improve or to use them for trust purposes without pursuing condemnation proceedings.
The result would be a California Mason-Dixon coastline dramatically divided between the north, in which the public trust doctrine is respected, and the south, where it is unrecognized. A dual system of rights would be created. Grantees whose title derives from Mexican grants would enjoy title free of the public trust, whereas those whose title did not originate with Mexico would hold their lands subject to the trust. The Treaty of Guadalupe Hidalgo requires only that the rights of Mexican grantees in their property shall be equal to that of citizens of the United States. (Treaty of Guadalupe Hidalgo, Art. VIII, 3 West’s Cal. Const. (1954) 727, 732.) In view of this language, there is no justification for holding that a deed from the United States to its own citizens conveys lesser rights than a deed issued to grantees from Mexico, or that the public trust exists in tidelands north of Sonoma but not south of that point as to tidelands included in former Mexican ranchos.
In view of our conclusion, we need not discuss the trial court’s findings that the public holds an easement in the property of defendants for the passage of fresh water to the Venice Canals and for water recreation, and that defendants’ predecessors had dedicated the property for use as public streets or waterways. All these uses are included within the public trust. (Marks v. Whitney (1971) 6 Cal.3d 251, 259-260 [98 Cal.Rptr. 790, 491 P.2d 374].)15
We have examined other contentions made by the parties and find them to be without merit.
The judgment is affirmed.
Bird, C. J., Newman, J., and Broussard, J., concurred.
Some of the defendants originally named in the action sold their interests in the lots to the present owners. Summa Corporation is the owner of the portion of lot C involved in this case; Venice Peninsula Properties and other defendants own lot R.
Southern California Gas Company, sued as a fictitious defendant, owns an easement for a pipeline which traverses the lagoon, and maintains an underground storage area on lot C which may extend beneath the waters of the lagoon. Its interest in this proceeding appears somewhat attenuated. The company sought a declaration that plaintiffs would be required to pay it compensation if relocation of the pipeline is required by the improvements which the city proposed to construct. However, there is no indication that these improvements will affect the company’s easements; plaintiffs’ briefs imply to the contrary. In any event, plaintiffs concede, as they must, that they will be required to compensate the company in the event any improvements they may make at some future time damage the company’s facilities. (Pub. Resources Code, § 6312.) !
Although the trial court found that the public’s right is “paramount” to the rights of the gas company, we do not understand this finding to mean that, contrary to section 6312, the improvements constructed by the gas company may be taken without payment of compensation.
Section 6308 provides: “Whenever an action or proceeding is commenced by or against a county, city, or other political subdivision or agency of the State involving the title to or the boundaries of tidelands or submerged lands that have been or may hereafter be granted to it in trust by the Legislature, the State of California shall be joined as a necessary party defendant in such action or proceeding....”
ln 1917, the state granted to the City of Venice any right which it had in tidelands within the boundaries of the city, in trust. The granting statute stated, “nothing contained herein shall in any way affect any property held or claimed under, through or from a Mexican grant or patent therefor within the present boundaries and jurisdiction of said city .... ” (Stats. 1917, ch. 77, p. 89.) The City of Los Angeles succeeded to the rights of Venice in these tidelands under a grant which excepted “any property held under, through or from a Mexican grant or patent ....” (Stats. 1945, ch. 1513, p. 2826.) There is no indication as to why these exceptions were made. The critical question in this proceeding is whether the public has retained an interest in the property in question. Whether that interest is held by the city, or by the state (as the trial court concluded), has no significant effect on the public’s rights in the property if such rights exist.
The owners of the ranch north of the Rancho Ballona appealed Drummond’s decision to the Secretary of the Interior; in affirming, the secretary referred specifically only to the boundary line dispute. From this circumstance, plaintiffs urge that Drummond’s decision is not binding because it was an intermediate decision affirmed by higher authority only to the extent that it decided the boundary dispute.
Plaintiffs claim that the question whether the “inner bay” shown on Hancock’s map was an arm of the sea was not necessary to Drummond’s decision because only the placement of the northern boundary was challenged; even if all the boundaries of the ranch were in issue, they argue, the question whether the “inner bay” was land or water was irrelevant to those boundaries. Defendants contend, on the other hand, that the area described as the “inner bay” would have been excluded from the grant if it had consisted of tidelands.
Experts in the field of geolSgy and geomorphology testified that the Ballona Lagoon is the remnant of a larger, wider, and deeper tidal body of water which existed in 1839 and for more than 900 years prior thereto. Their conclusions were based in part on surveys of the area by the federal government in 1876, 1887, and 1896, which showed the lagoon as an arm of the sea in a configuration consistent with the map drawn by Hancock, and scientific tests of the subsurface of the lagoon.
California did not acquire title as an incident of sovereignty to tidelands which were patented under the Act of 1851. (E.g., United States v. Coronado Beach Co. (1921) 255 U.S. 472, 488 [65 L.Ed. 736, 742, 41 S.Ct. 378]; People v. San Francisco (1888) 75 Cal. 388, 398 [17 P. 522].)
Law 111 of Title XXVIII of Las Siete Partidas, the law in effect while California was a part of Mexico, provided, “The things which belong in common to the creatures of this world are the following, namely, the ... sea and its shores, for every living creature can use each of these things according as it has need of them. For this reason every man can use the sea and its shore for fishing or for navigation, and for doing everything there which he thinks may be to his advantage.” Law VI provided, “Rivers, harbors, and public highways belong to all persons in common.... ” (Las Siete Partidas, CCH (Spain) (1931) pp. 820-821.) The Mexican law originated in 13th century Spain under Alfonso the Wise. (Stevens, The Public Trust, supra, 14 U.C. Davis L.Rev. at p. 197.)
Indeed, according to the expert witness, Mexican law prohibited the alienation of tidelands. While we are not aware of any authority on the question whether a conveyance of tidelands by Mexico (perhaps erroneously) preserved the public’s right in the land, the concept of retention by the public of rights in lands conveyed by the government to private parties was not alien to the law of Mexico, as we shall see. In the absence of any indication to the contrary, we assume that tidelands conveyed by Mexico remained subject to the public’s interest.
For example, in People v. California Fish Co., supra, 166 Cal. 576, 584, tidelands are referred to as belonging to the state in its sovereign character, and in Illinois Central Railroad v. Illinois (1892) 146 U.S. 387, 452 [36 L.Ed. 1018, 1042, 13 S.Ct. 110], the government’s interest in tidelands is described as “a title held in trust for the people of the state.... ”
We disapprove dictum in San Diego County Archeological Society, Inc. v. Compadres (1978) 81 Cal.App.3d 923, 927 [146 Cal.Rptr. 786], to the effect that the public trust doctrine applies only to property to which the state has at one time held title.
ln Boquillas, the plaintiff, who had received a grant of land from the State of Sonora, claimed that a patent to the land issued under a law similar to the Act of 1851 carried with it a preference to take water as a riparian landowner.
The United States argued that the tidelands belonged to California, which had acquired title to them upon its admission to the Union. Rejecting this argument, the court stated, “But the title of the State was subject to prior Mexican grants. The question whether there was such a prior grant and what were its boundaries were questions that had to be decided in the proceedings for confirmation and there was jurisdiction to decide them as well if the decision was wrong as if it was right. The title of California was in abeyance until those issues were determined as the decree related back to the date of the original grant.... [Ajlthough ... the grant could have been construed more narrowly, that was a matter to be passed upon and when the decree and the patent went in favor of the grantee it is too late to argue that they are not conclusive against the United States.... [Hjowever arrived at it was adopted by the United States for its grant and it cannot now be collaterally impeached.” (255 U.S. at pp. 487-488 [65 L.Ed. at pp. 741-742].)
The court reasoned in part that “a claim of a right to permanent occupancy of land is one of far reaching effect, and it could not well be said that lands which were burdened with a right of permanent occupancy were a part of the public domain and subject to the full disposal of the United States.... Surely a claimant would have little reason for presenting to the land commission his claim of land, and securing a confirmation of that claim, if the only result were to transfer the naked fee to him, burdened by an Indian right of permanent occupancy.” (265 U.S. at p. 484 [65 L.Ed. at pp. 1113-1114].)
Our opinion is not to be understood as deciding matters which are raised by the parties but are not necessary to the determination of the issue before us. For example, although the state alleged in its cross-complaint that portions of the Ballena Lagoon which have been filled are still subject to the public trust, that issue is not involved in the present proceeding, since the property here consists entirely of tidelands.