The opinion of the Court was delivered by
O’HERN, J.The question in this case is whether the unauthorized use of public property for private recreational activities thereby puts the property “in dangerous condition” under N.J.S.A. 59:4-2 of the New Jersey Tort Claims Act, N.J.S.A 59:1-1 to :12-3 (the Act or the New Jersey Act), when the recreational activities themselves are risky and pose danger to the participants. In this ease a man dove from a county bridge into shallow tidal waters, suffering a paralyzing injury. We conclude that however tragic the accident, its cause was not the condition of the bridge but the dangers of unsupervised recreational activity for which there is no public-entity liability under the Act.
*38I
For purposes of this appeal, we accept the statement of facts set forth in plaintiffs briefs. (For convenience, we refer only to the injured plaintiff, Richard Levin. The claims of the other plaintiffs are derivative.) On the evening of July 23, 1987, Levin and two companions stopped at the Garden Road Bridge (the bridge) between Pittsgrove and Vineland to swim in the Maurice River. They had arrived by automobile from the Cumberland County side of the bridge and had parked in the turnoff on the north side of the bridge, the Salem County side.
Many others "were at or near the bridge on that evening. For decades local residents had used the bridge and the surrounding area along the Maurice River for swimming and diving. This local “swimming hole” spans the border between Vineland (Cumberland) on the east and Pittsgrove (Salem) on the west. When Levin arrived at the bridge, several people were diving from the bridge into the river, seven feet below the bridge span. After observing the divers, Levin went to the north side of the bridge. When he dove into the river, his head struck a submerged sandbar. As a result, he sustained a fracture of the sixth cervical vertebra and was rendered a quadriplegic.
The counties of Cumberland and Salem jointly own, maintain, and control the Garden Road Bridge and are responsible for the regulation of activities on or near it. At the site of the bridge, the Maurice River passes through a picturesque woodland area. Gently sloping banks descend to the river on each side, and a sandy bathing beach exists adjacent to it. The site has been used by the public as a local swimming hole and for other water-related activities, such as sunbathing, fishing, canoeing, swimming, and diving from the river bank. Levin, in fact, had frequented the site as a child, and his family had enjoyed several outings there. The present bridge was constructed to replace the steel truss bridge that had been on the site for many years. It serves a rural, two-lane road. The bridge has a parapet, or low wall, at its edge, separated from the road by a wide sidewalk. Visitors to the *39bridge often used the parapet, which is twenty-seven inches high and twelve inches wide, as a diving'platform.
The record contains evidence that defendants knew that the area surrounding the Garden Road Bridge was used as a recreational site and that the bridge itself was used as a diving platform. The artificial bathing beach, parking areas, footpaths, canoe-rental signs, and the large numbers of swimmers, divers, and fishers who congregated at the site were obvious indications to the public bodies that the bridge area had been used and was being used by the public as a recreational site. Recent photographs offered in evidence depicted young people diving head first from the bridge into the Maurice River below.
In 1978, seventeen-year-old Mary Lou Quesenberry had suffered a similar accident when she dove into the river. During the course of the subsequent lawsuit the defendants received an engineering report detailing the hazard inherent in the placement of a low bridge wall over a body of water known to be used for recreation. The report indicated that the hazard at the site was the product of constantly-shifting sandbars below that part of the bridge where one would believe the water was the deepest, combined with the coloration of the water. The waters of the Maurice River are of a reddish color, commonly referred to as cedar water. The sandbars resulted from the widening of the river channel when the bridge was constructed in 1971. The report had recommended that the counties (1) construct a protective screen or fence to bar access to the river from the bridge, (2) post effective signs on the bridge approaches and spans, and (3) police and supervise the recreational activities at the site. Notwithstanding those recommendations, at the time of Levin’s accident neither county had altered the structure or design of the bridge. Since the filing of this suit, Salem County has erected a six-foot-tall chain-link fence on both sides of the Garden Road Bridge within its jurisdiction. At the end of the fence vertical “wingwalls” extend across the parapet and over the water, preventing access to the parapet behind the fence.
*40In 1986, the Salem County Board of Chosen Freeholders passed a resolution restricting access to county bridges and prohibiting swimming, fishing, or diving from any bridge. Plaintiff asserted that the resolution had not been enforced. Prior to plaintiffs accident, Salem County did not restrict access to the waters from the bridge or notify the public of the danger inherent in its use as a diving platform. Salem County maintained that it had posted signs on the bridge stating “no fishing, no loitering on bridge” and “no swimming from bridge by order of Freeholders,” although plaintiff disputed that those signs had been in place at the time of the accident. Cumberland County also maintained that it had posted “no diving” signs on the bridge, although it had never enacted an ordinance prohibiting diving at the bridge. Plaintiff disputed that these signs had been in place on the date of the accident. Plaintiff was unaware of any sign, ordinance, or prohibition restricting the use of the bridge and the surrounding area. He had often swum at the site, had never believed its recreational use was prohibited, and had often observed others diving from the bridge. He had never been informed that he should leave the area or restrict his activities, nor was he aware that anyone else had been so informed.
Plaintiff sued both counties and the two towns within each county, Pittsgrove and Vineland, that border the bridge. The trial court granted summary judgment in favor of all the public entities. Pittsgrove moved unopposed for summary judgment and was dismissed from the case. Plaintiff did not appeal that dismissal. Salem then moved for summary judgment. In granting Salem’s motion, the trial court specifically found that (a) warning signs had been posted on the bridge at the time of the accident, (b) Salem County had passed an ordinance prohibiting diving from county bridges, and (c) the sole intended use for bridges is for vehicular and pedestrian traffic. The court found “as a matter of law [that] this bridge cannot be deemed to be a dangerous condition of public property.”
After Salem’s motion, defendants Vineland and Cumberland also moved for summary judgment. Vineland argued that because the *41court had previously ruled that the bridge was not in dangerous condition, plaintiff could not sustain a cause of action against Vineland. Vineland further argued that the bridge was not “a property” of the municipality. Lastly, Vineland disputed plaintiffs allegation that the municipality had been negligent because at one time it had patrol cars on the bridge but at the time of the accident it did not. Vineland argued that a public entity does not have a duty to patrol property that does not belong to it. The court found Vineland’s points essentially unrefuted and granted its motion. In granting Cumberland’s motion, the court incorporated all of the reasons it had cited for granting Salem’s motion that also applied to Cumberland. Presumably, the court’s finding that the bridge was not “a dangerous condition” was one of those reasons.
The Appellate Division affirmed, substantially for the reasons stated by the Law Division in ruling on the summary-judgment motions. The Appellate Division considered itself bound by Burroughs v. City of Atlantic City, 234 N.J.Super. 208, 560 A.2d 725 (App.Div.), certif. denied, 117 N.J. 647, 569 A.2d 1345 (1989). We granted plaintiffs petition for certification, 130 N.J. 18, 611 A.2d 655 (1992). Plaintiff claims generally that the decisions of the lower courts constitute a gross miscarriage of justice. Because those decisions apply to defendants Salem, Vineland, and Cumberland, they have all responded to plaintiffs petition.
II
We are required again to resolve the proper relationship between the liability and immunity provisions of the Act. Rochinsky v. State, Department of Transportation, 110 N.J. 399, 541 A.2d 1029 (1988), sets forth the principles applicable to an action brought under the Act.
Plaintiff alleges that the absence of adequate warnings on the bridge or the failure to supervise the recreational activities or to erect a fence at the edge of the bridge caused his injuries. Defendants assert that the unauthorized and, indeed, illegal use of the property caused the injuries. Plaintiff realizes that liability *42cannot be based on the failure to supervise, because N.J.S.A. 59:2-7 specifically immunizes public entities from liability for the failure to provide supervision of public recreational facilities. See, e.g., Stempkowski v. Borough of Manasquan, 208 N.J.Super. 328, 333, 506 A.2d 5 (App.Div.1986) (affirming grant of summary judgment for borough because plaintiffs claim of failure to supervise could not sustain cause of action under N.J.S.A. 59:2-7). Plaintiff relies, however, on the proviso in N.J.S.A. 59:2-7 that “nothing in this section shall exonerate a public entity from liability for failure to protect against a dangerous condition as provided in chapter 4.”
Chapter 4 of the Act, specifically N.J.S.A. 59:4-2, imposes liability on a public entity for injury caused by a condition of its property “if the plaintiff establishes that the property was in dangerous condition at the time of the injury, that the injury was proximately caused by the dangerous condition, [and] that the dangerous condition created a reasonably foreseeable risk of the kind of injury * * * incurred.” The plaintiff must also establish that the public entity was responsible either through its employees for creating the dangerous condition or had actual or constructive notice of the condition sufficiently before the injury to have taken measures to protect against the dangerous condition, provided that the entity will not be liable if the action taken to protect against the condition was not “palpably unreasonable.” Ibid. N.J.S.A. 59:4-1.a. defines “dangerous condition” as “a condition of property that creates a substantial risk of injury when such property is used with due care in a manner in. which it is reasonably foreseeable that it will be used.”
Defendants’ principal argument before us is that to use property illegally cannot be to use it with due care, no matter how reasonably foreseeable the use. Applying that principle to Salem County, the fact that the public body had adopted a resolution forbidding diving from the bridge would immunize it from liability. We do not find that to be a satisfactory principle of decision. Were it so, a public entity could easily insulate itself from liability with respect to dangerous conditions of its property merely by *43enacting ordinances that, for example, would direct parties not to walk near the edge of a broken railing or near the weakened portion of a floor in public facilities.
Rather, we believe that the issues here require us to identify the culpable cause of the accident and to ask if that “identified cause or condition is one that the Legislature intended to immunize.” Weiss v. New Jersey Transit, 128 N.J. 376, 380, 608 A.2d 254 (1992). With respect to the defendants, we perceive only three possible culpable causes of the accident: (1) the design of a bridge with a parapet low enough for divers to scale it and dive into the waters; (2) the failure of the public bodies either to adopt or to enforce ordinances with attendant descriptive signs prohibiting the activities; or (3) the failure of the public bodies to supervise the recreational activities that they knew were taking place on the bridge. Concerning the first point, if the dangerous condition of the property were the omission of a chain-link fence from the original design of the bridge, that omission would be insulated from liability by the plan-or-design immunity granted under N.J.S.A. 59:4-6. Concerning the second and third points, plaintiff recognizes, as he must, that the failure to adopt or to enforce laws and the failure to supervise public recreational facilities are insulated from liability under specific immunities of the Act, respectively, N.J.S.A. 59:2^1 and -7.
As noted, however, plaintiff rests his argument on N.J.S.A. 59:4-2. Plaintiff contends that the use of the property as a recreational facility, when the public body knew of the use, created a dangerous condition of property. He claims that the absence of signs or other interdiction contributed to the dangerous condition. He submits that a jury should have been permitted to decide (1) if the property was being used with due care, in a way that was reasonably foreseeable to defendants, and (2) if such use created a dangerous condition on the property. Plaintiff relies on language in Burroughs, supra, that “whether a dangerous condition is present depends on a combination of factors relating to physical condition, permitted conduct, and objectively foreseeable behav*44ior.” 234 N.J.Super. at 218-19, 560 A2d 725. In Burroughs, an ocean-beach boardwalk used primarily for walking, jogging, and cycling had been adapted, because of its proximity to the water, to a use not intended: diving. If Atlantic City, knowing of the diving, had done nothing to prohibit that unintended use, diving could have become a tacitly-permitted use. The Burroughs court declined to find liability, however, because the City had posted signs prohibiting diving from the boardwalk and its lifeguards had been instructed to stop the activity when they observed it. Id. at 219, 560 A2d 725. Plaintiff asserts that he has established a factual issue in this case by demonstrating that the public bodies had not effectively interdicted diving and thus had tacitly permitted the use.
We are concerned that the premise of the Burroughs case on which plaintiff relies, namely, that a dangerous condition of property may arise from a “combination of factors relating to physical condition, permitted conduct, and objectively foreseeable behavior,” id. at 218-19, 560 A2d 725, may be too broad in the context of this case. Heretofore, courts have understood a “dangerous condition” as defined in N.J.S.A. 59:4-l.a to refer to the “physical condition of the property itself and not to activities on the property.” Sharra v. City of Atlantic City, 199 N.J.Super. 535, 540, 489 A.2d 1252 (App.Div.1985) (citing Rodriguez v. N.J. Sports & Exposition Auth., 193 N.J.Super. 39, 472 A.2d 146 (App.Div.1983), certif denied, 96 N.J. 291, 475 A.2d 586 (1984)); accord Cogsville v. City of Trenton, 159 N.J.Super. 71, 386 A.2d 1362 (App.Div. 1978) (holding that exposure to dog bites from allegedly vicious dog owned by tenant in city dwelling did not constitute dangerous condition of property); Setrin v. Glassboro State College, 136 N.J.Super. 329, 346 A.2d 102 (App.Div.1975) (holding that criminal conduct of one student in attacking another student during on-campus racial incident did not constitute dangerous condition of property). •
In King by King v. Brown, 221 N.J.Super. 270, 534 A.2d 413 (App.Div.1987), the court considered the activity on the property, in addition to its physical condition, in deciding whether a danger*45ous condition existed. There, Brown, a motorist, struck the plaintiff, a pedestrian, as he attempted to cross a municipal roadway. Plaintiff argued that three public entities responsible for the design of the highway area should be liable for his injuries because the combination of a high volume of vehicular and pedestrian traffic had created a dangerous condition of property. Id. at 273-74, 534 A.2d 413. In finding for the public entities, the King court stated that “application of the dangerous condition standard requires consideration of both the physical characteristics of the public property as well as the nature of the activities permitted on that property." Id. at 275, 534 A.2d 413 (emphasis added). However, the Burroughs court observed that because the motorist and the pedestrian in King “were both using the public property for its permitted and intended purpose, i.e., for pedestrian and vehicular traffic, ‘foreseeable’ use was not an issue.” 234 N.J.Super. at 217, 534 A.2d 413 (emphasis added). Thus, the Burroughs court concluded that the test enunciated in King, that is, “ ‘whether the condition complained of creates a substantial risk of injury despite the exercise of due care,’ ” presumed that the use of the public premises was a permitted one. Id. at 218, 534 A. 2d 413 (quoting King, supra, 221 N.J.Super. at 275, 534 A.2d 413).
Furthermore, we suspect that the Burroughs doctrine, on which plaintiff relies, would effectively eliminate the plan-or-design immunity conferred under N.J.S.A. 59:4-6. The counties designed the bridge to carry traffic and pedestrians. Usually the form of an object follows its function. See David Outerbridge, Bridges 8 (1989). The plan-or-design immunity shelters the bridge designers’ decision to accept or reject the concept of posting a chain-link fence along the sides of this rural span. Compare, Daniel v. State, Dep’t of Transp., 239 N.J.Super. 563, 571 A.2d 1329 (App. Div.) (presenting jury question on whether State could claim plan- or-design immunity because specific feature allegedly creating dangerous condition — a “ramp” that could “catapult” cars across highway median — arguably was result of routine maintenance work rather than an approved feature of plan or design), certif. denied, 122 N.J. 325, 585 A.2d 343 (1990). Declining to follow the *46approach of California, the Legislature states in the official Comment to N.J.S.A. 59:4^6 that “[i]t is intended that the plan or design immunity provided in this section be perpetual.” “[0]nce the immunity attaches,” the Comment continues, liability for changed circumstances affecting a plan or design “has been specifically rejected as unrealistic and inconsistent with the thesis of discretionary immunity.” Plan-or-design immunity is not perpetual under California law. See Baldwin v. California, 6 Cal. 3d 424, 99 Cal.Rptr. 145, 491 P.2d 1121 (1972).
III
In other essentials, however, the California Tort Claims Act was the model for the New Jersey Act. Speaks v. Jersey City Housing Auth., 193 N.J.Super. 405, 411-12, 474 A.2d 1081 (App. Div.), certif. denied, 97 N.J. 655, 483 A.2d 177 (1984). Accordingly, to look to California for guidance in interpreting the Act is logical. California tends to view the issue of responsibility for the injury in terms of causation: Is there some defect in the property that caused the injury or is there some other cause of the injury? Campbell v. City of Santa Monica, 51 Cal.App.2d 626, 125 P.2d 561 (1942), a case that arose under the California Public Liability Act (predecessor to the California Tort Claims Act), provides a slightly-obverse example of the problem with the Garden Road Bridge. In that case, the driver of an unauthorized motor vehicle negligently traversed a promenade constructed for pedestrian traffic and injured a pedestrian. .The court reasoned that the liability imposed for a dangerous or defective condition of public streets and property does not extend to activities on the property, such as motor vehicles entering on streets or highways, but only against risks directly due to physically dangerous or defective streets or sidewalks.
Here the Promenade itself was neither dangerous nor defective. The harm in this case was caused, not by the condition of the Promenade or the want of barriers or signs barring its use by vehicles without a permit, but by the negligent operation of a motor vehicle. * * * The city owed the plaintiffs no duty to restrict the use nor to barricade against motorists who did not hold permits to use it. The Promenade *47is not dangerous nor defective just because it is so constructed that motor vehicles can readily drive upon and along it.
[Id. 51 Cal.App.2d at 629-30, 125 P.2d at 563.]
Other California cases, interpreting that state’s Tort Claims Act, have followed the Campbell court’s interpretation of dangerous condition of public property.
A study of the cases interpreting section 830 [of the California Tort Claims Act covering a dangerous condition of property] and its predecessor acts shows that they interpret section 830 as requiring the physical condition of the public property to be in a dangerous or defective condition involving reasonable risk to the public. In Campbell v. City of Santa Monica * * *, [51 Cal.App.2d 626] 125 P.2d 561 * * * the court said, * * ■* “harm in this case was caused, not by the condition of the Promenade or the want of barriers or signs barring its use by vehicles without a permit, but by the negligent operation of a motor vehicle.”
[Sykes v. County of Marin, 43 Cal.App. 3d 158, 161,
117 Cal.Rptr. 466, 468 (1974) (emphasis added).]
Bartell v. Palos Verdes Peninsula School District, 83 Cal. App.3d 492, 147 Cal.Rptr. 898 (1978), is a case much like ours. Even though the school district allegedly knew that children used its playground for skateboarding and took no measures to prevent the activity, the court found that plaintiffs failed to state a cause of action for a “dangerous condition of public property” because the injury was the direct result of the childrens’ dangerous conduct, not a defect in the physical condition of the property.1 The Bartell court cited Campbell as well for the proposition that a physical defect in the property must exist as a precondition to public-entity liability. Id. 83 Cal.App. 3d at 497, 147 Cal.Rptr. at *48900. True, the California cases are not in perfect accord, but most appear to preserve that distinction. In Fredette v. City of Long Beach, 187 Cal.App.3d 122, 231 Cal.Rptr. 598 (1986), the claimant was injured when he dove from a pier under reconstruction, which had previously led to a water float used as a diving platform. The jury found no dangerous condition of property. The appeals court affirmed, observing that “[cjases holding public entities liable for failure to warn of dangerous conditions are based on the presence of an actual dangerous physical defect or an otherwise dangerous condition which was not apparent to persons using the property with due care.” Id. 187 Cal.App.3d at 131-32, 231 Cal.Rptr. at 603.
The California Supreme Court has tilted in both directions. In Hayes v. California, 11 Cal.3d 469, 113 Cal.Rptr. 599, 521 P.2d 855 (1974), the court, refusing to impose liability for injuries sustained on public property due to inadequate security, emphasized that some physical feature of the property has been at least a contributing defect if not the defect in decisions imposing liability for injury caused by a dangerous condition of property.2 Later, in Peterson v. San Francisco Community College District, 36 Cal.3d 799, 205 Cal.Rptr. 842, 685 P.2d 1193 (1984), the court held that a public-school authority that failed to trim foliage in a secluded part of the school property or to warn of the danger of criminal acts could be held liable for maintaining a dangerous condition of public property. The court emphasized, however, the special relationship between the public entity and the student as invitee *49and found that the factors of prior assaults and the failure to trim the foliage “indicate that there is moral blame attached to the defendants’ failure to take steps to avert the foreseeable harm.” Id. 36 Cal.3d at 814, 205 Cal.Rptr. at 851, 685 P.2d at 1202.
The corollary of the proposition — that we look to effects to determine whether a dangerous condition of property exists— would be that whenever danger exists, so does a dangerous condition of property. Heretofore our cases have not taken that approach. To do so now would require disapproval of many prior decisions both of this Court and lower courts, such as Weiss v. New Jersey Transit, supra, 128 N.J. 376, 608 A.2d 254 (we could have characterized the grade crossing as a dangerous condition of property, but did not), and Stempkowski v. Borough of Manasquan, supra, 208 N.J.Super. 328, 506 A.2d 5 (the Appellate Division could have found the unguarded beach to be a dangerous condition of property, but did not).
Of course, a physical defect in the property, for example, a missing window, combined with the foreseeable neglect or misconduct of third parties, may result in the imposition of liability on the public entity because the combination renders the property unfit. Some conditions of the property itself impair the safety of its intended or foreseeable uses. See, e.g., Speaks, supra, 193 N.J.Super. at 412, 474 A.2d 1081 (finding that housing authority’s failure to replace missing window created dangerous condition in common yard frequented by children directly under window when foreseeable risk existed that someone would drop or throw object out of window).
IV
In this cáse, there was no missing plate, no broken bolt, no defect in the bridge itself that caused or contributed to cause the tragic accident. The danger arose because the bridge was where the shallow water was. No other activity or inactivity of the public entities in this case forms a basis for liability under the Act *50(such as the failure to adopt or enforce laws prohibiting diving, or to provide supervision of the diving).
The judgment of the Appellate Division is affirmed.
In Torkelson v. City of Redlands, 198 Cal.App. 2d 354, 17 Cal.Rptr. 899 (1961), the court found a dangerous condition of property to exist when a child at play was swept by storm waters into an unfenced drain. However, the Bartell court later distinguished Torkelson on the grounds that the cause of the injury was an "inherent danger or dangerous design of the property itself,” 83 Cal.App.3d at 498 n. 4, 147 Cal.Rptr. at 900 n. 4, for which the California Tort Claims Act does not extend perpetual immunity to public entities. See supra at 46, 626 A.2d at 1096. We note that the New Jersey Act would immunize the defective design of a storm drain under N.J.S.A. 59:4-6, as well as any design feature of the Garden Road Bridge.
In so ruling, the Hayes court vacated the Court of Appeals decision, which had ruled that
[t]hc statute [allowing recovery based on a dangerous condition of property] is not restricted to the inherent quality of the property itself, but rather focuses on the impact of the condition upon the environment or users. It is the effect which determines whether a dangerous condition exists, not the inner nature of the property. Whether a dangerous condition exists can only be determined by examining the total quantum of facts pertinent to a controversy.
[Hayes v. California, 111 Cal.Rptr. 856, 862, (1973) (citations omitted).]