The opinion of the Court was delivered by
STEIN, J.Plaintiff instituted this action to hold the State of New Jersey accountable for the death of her husband and the serious injuries she sustained when their small fishing boat was swept over the spillway on Union Lake Dam, located on a 4,300-acre recreational tract owned by the State. The gist of the complaint and the affidavits opposing the State’s summary judgment motion was that because of the configuration of the spillway at higher-than-normal water levels, the flow velocity near the spillway created a “dangerous condition” for small fishing boats, providing a basis for liability under the New Jersey Tort Claims Act (the “Act”). See N.J.S.A. 59:4-2. The Law Division denied the State’s motion for summary judgment. The Appellate Division reversed, 222 N.J.Super. 420 (1988), holding that the State was immune from liability pursuant to *261N.J.S.A. 59:4-8 and -9 because Union Lake is “unimproved public property.” We granted certification, 111 N.J. 565 (1988), and now reverse.
I.
Union Lake Dam is one of the oldest dams in the State of New Jersey. Built in the nineteenth century, the 2,000-foot-long, thirty-five-foot-high, earthen structure impounds the Maurice River and creates Union Lake. It has a 200-foot wide concrete and masonry spillway over which excess water flows into the Maurice River. The dam lies at the southernmost tip of a 4,300-acre wildlife-management area that was transferred to the State of New Jersey in 1982.
On the morning of June 22, 1983, Marie Troth and her husband, Floyd, went fishing on Union Lake. The Troths lowered their fourteen-foot aluminum-hulled fishing boat into the lake from the boat-launching ramp, located at the same end of the lake as the dam. Turning on their electric trolling motor, the Troths made their way across the lake to an area near the dam. While the two were trolling, the fishing lines became entangled in undergrowth. Mr. Troth reversed the trolling motor and backed up in the direction of the snag. As they were retrieving the fishing lines, the Troths realized that the current was pulling their boat towards the spillway. The small electric trolling motor was unable to resist the current and the boat was drawn closer to the spillway. Mr. Troth shifted to a position where he could start the ten-horsepower gas-driven motor. He tried several times but the motor would not turn over. As the boat approached the mouth of the spillway, Mrs. Troth saw “one wire rope which in large part was submerged beneath the water.” She reached down and grabbed onto the cable, but was unable to prevent the boat from being swept over the crest of the spillway. Both Marie and Floyd Troth were thrown from the boat as it passed over the dam. As she was falling, Mrs. Troth saw the boat flip over and strike her *262husband. Mr. Troth drowned and Mrs. Troth suffered serious injury.
The Division of Fish, Game and Wildlife dispatched an investigator, who arrived soon after the accident. The investigator, who was familiar with Union Lake, checked the water-depth gauge and found the water level to be above normal. The investigator found a single safety cable stretched across the spillway. He also noted that there was “higher than normal water and a strong current was evident.” The investigator also observed two signs facing the lake on either side of the spillway bearing the legend “KEEP AWAY.”
In preparation for this litigation, plaintiff retained an engineering expert to furnish a report on the safety of Union Lake Dam. According to that report, the spillway has a maximum discharge capacity of 19,000 cubic feet of water per second. At capacity, the water depth across the 200-foot length of the spillway is 6.5 feet. At this level, the water velocity at the crest of the spillway is 14.5 feet per second. The report observes that “[a] small boat cannot be controlled at such a rate of flow.” At half-capacity, water depth at the spillway is 4.1 feet and has a velocity at the crest of 11.5 feet per second, a flow that the report indicates “would still result in a velocity uncontrollable in a small boat.”
From these flow velocities, plaintiffs expert concluded:
The velocities calculated above are those that would exist at the spillway crest. At locations in the reservoir, at some distance from the spillway, the velocities would be much diminished, but a current toward the spillway would still exist. This situation represents an insidious trap for a boat could begin a gentle drift, with its occupants unaware of the motion, until it had accelerated to the point where escape from the grip of the current became impossible.
Plaintiff’s engineering expert inspected the dam in February 1985. At that time, two wire-rope barriers were stretched across the crest of the spillway. The engineering report indicates that at full discharge capacity the spillway-wire barrier would be completely submerged over its entire length; at half capacity, the barrier would be submerged over most of its *263length. The report concluded that a floating-barrier boom would have been a more effective safety measure.
Plaintiff’s report summarizes its findings as follows:
a) The unrestricted use of Union Lake by small boats, together with the flow of water from the lake over the dam spillway, constituted a very dangerous condition.
b) The State of New Jersey had actual notice of the existence of this dangerous condition, as evidenced by the placement of the warning signs and a wire rope barrier at the spillway.
c) Warning signs placed only on the dam itself were totally inadequate.
d) Barriers which a small boat could pass under at low flows, and which would be submerged at high flows, were defective.
e) Other appropriate measures were available to provide more complete protection to the boating public.
Plaintiff’s engineering report incorporates an earlier engineering report prepared for the State of New Jersey by the United States Army Corps of Engineers. This report was prepared pursuant to the National Dam Inspection Act, 33 U.S.C.A. § 467a, and transmitted to the Governor in September 1978. The report concluded that Union Lake Dam is “a high hazard potential structure.”1 In particular, the Corps of Engineers found that the “spillway is considered to be inadequate since 61% of the Probable Maximum Flood [ ] would overtop the dam.” The report recommended that the State promptly institute a number of safety measures: an engineering study of the *264spillway and implementation of necessary remedial actions to insure its adequacy and prevent overtopping; installation of an interim system notifying local civil defense authorities of dangerous conditions during heavy storms; providing spillway-gate operators with flow information and water elevations; and installation of a gauge to record reservoir levels during peak flows.
With respect to the State’s failure to implement the recommended safety measures, the plaintiff’s expert concludes:
Unless sufficient explanation can be provided for disregarding the recommendations contained in the Berger [Army Corps of Engineers] report, and we can hardly conceive any, a valid theory can be developed for wanton disregard for safety provisions at the site. Lack of concern for safety of the dam system itself during high flow conditions would naturally foster a more casual attitude toward boaters during these same conditions. Regular users of Union Lake, who have operated their boats safely in the vicinity of the dam during low-flow periods, could be lulled into a sense of security that would be unwarranted at higher flows (and hence more rapid velocities near the dam). The owners and operators of the dam, having been alerted to high-flow hazards, should have responded with more effective safety and warning devices * * *.
The State moved for summary judgment, contending that it was immune from liability under the New Jersey Tort Claims Act because Union Lake was “unimproved public property,” N.J.S.A. 59:4-8 and -9. It argued in the alternative that it was entitled to immunity under the Landowner Liability Act, N.J.S.A. 2A:42A-1 to -7, asserting that it owed no duty to people using Union Lake for “sport and recreational activities.” N.J.S.A. 2A:42A-3. After the Law Division denied the summary judgment motion, the Appellate Division granted the State leave to appeal. In her responding brief, plaintiff argued for the first time that summary judgment should be denied because of a factual issue over whether the State’s employees had been negligent in supervising the recreational use of Union Lake. See N.J.S.A. 59:3-11.
The Appellate Division reversed, concluding that the State’s immunity from liability for injuries caused by a dangerous condition of “unimproved public property” compelled the grant of summary judgment.
*265We are satisfied there is no factual issue as to whether Union Lake as part of the larger tract acquired by the State for conservation and recreational purposes is “unimproved public property” within the meaning of N.J.S.A. 59:4-8. Nor, that the existence of the earthen dam and concrete spillway, although an artifically created structure, causes the nature of this property to be other than unimproved. This conclusion is compelled by legislative directive that “the term unimproved public property should be liberally construed.” Comment to N.J.S.A. 59:4-8 and 9, supra. Clearly, the dam is a necessary and integral part of the lake and thus cannot be considered, as urged by plaintiffs, as a separate and distinct parcel of the State-owned land having no relationship to the unimproved aspect of the entire tract. In comparing the nature and extent of this man-made improvement with the nature and extent of the lake itself it is evident that the existence of the dam cannot detract from the overall unimproved character of this portion of the Union Lake Wildlife Management Area. [222 N.J.Super. at 425-26.]
The Appellate Division also determined that there was no factual issue raised by plaintiffs contention that the State’s liability could be premised on the negligent supervision of boating activity by State employees. The court acknowledged that State conservation officers routinely patrolled the lake for the purpose of enforcing fish and game laws, and also periodically inspected the dam and spillway. Id. at 425. The court concluded that there was
no proof that State employees undertook the supervision of the recreational use of the lake. The routine patrols of the conservation officers were directed to enforcement of the applicable laws and regulations. Their inspection of the spillway, being “an incidental undertaking at the same place and only tangentially related to the recreational activity.” N.J.S.A. 59:3-11. [Id. at 427.]
The Appellate Division did not address the State’s contention that it was also afforded immunity under the Landowner’s Liability Act. Id. at 422.
II.
Because this action is predicated on the New Jersey Tort Claims Act, N.J.S.A. 59:1-1 to 12-3, our analysis begins with the Act’s relevant provisions and with the comments of the Attorney General’s Task Force Report (Task Force Report), which provide the legislative history for the Act. J.S. Fitzpatrick, Governmental Tort Liability in New Jersey 17 (1986) (Fitzpatrick). As a general rule, the analytical “approach *266should be whether an immunity applies and if not, should liability attach.” N.J.S.A. 59:2-1, comment. By providing that “ ‘public entities are immune from liability unless they are declared to be liable by an enactment,’ ” the Legislature intended to “ ‘provide a better basis upon which the financial burden of liability may be calculated, since each enactment imposing liability can be evaluated in terms of the potential cost of such liability.’ ” Ibid. (quoting California Law Revision Comm’n, Recommendations Relating to Sovereign Immunity 811 (1963)).
Consistent with that general policy, two sections of the Act, N.J.S.A. 59:4-8 and -9, limit liability of public entities for injuries on unimproved property. A third section precludes liability for the failure to supervise, but not for negligent supervision. N.J.S.A. 59:3-11. The two sections pertaining to unimproved property provide:
Neither a public entity nor a public employee is liable for an injury caused by a condition of any unimproved public property, including but not limited to any natural condition of any lake, stream, bay, river or beach. [N.J.S.A. 59:4-8.]
Neither a public entity nor a public employee is liable for any injury caused by a condition of the unimproved and unoccupied portions of the tidelands and submerged lands, and the beds of navigable rivers, streams, lakes, bays, estuaries, inlets and straits owned by the State. [N.J.S.A. 59:4-9.]
When explaining the purpose of these two sections, the Attorney General’s Task Force commented:
Sections 59:4-8 and 59:4-9 reflect the policy determination that it is desirable to permit the members of the public to use public property in its natural condition and that the burdens and expenses of putting such property in a safe condition as well as the expense of defending claims for injuries would probably cause many public entities to close such areas to public use. In view of the limited funds available for the acquisition and improvement of property for recreational purposes, it is not unreasonable to expect persons who voluntarily use unimproved public property to assume the risk of injuries arising therefrom as part of the price to be paid for benefits received. A similar statutory approach was taken by the California Legislature. [N.J.S.A. 59:4-9, comment (citations omitted).]
After pointing out that “[t]he State of New Jersey possesses thousands of acres of land set aside for the specific purpose of recreation and enjoyment,” the comment concluded:
The exposure to hazard and risk involved is readily apparent when considering all the recreational and conservation uses made by the public generally of the *267foregoing acreages, both land and water oriented. Thus in sections 59:4-8 and 59:4-9 a public entity is provided an absolute immunity irrespective of whether a particular condition is a dangerous one.
In addition it is intended under those sections that the term unimproved public property should be liberally construed and determined by comparing the nature and extent of the improvement with the nature and extent of the land. Certain improvements may be desirable and public entities should not be unreasonably deterred from making them by the threat of tort liability. [Ibid.]
Although we have not previously construed N.J.S.A. 59:4-8 and -9, the Law Division and the Appellate Division have arrived at conflicting constructions of the sections. The Law Division has construed N.J.S.A. 59:4-8 to provide immunity only for “natural conditions.” Diodata v. Camden County Park Comm’n, 162 N.J.Super. 275, 289 (1978). In Diodata, the court determined that a park commission would not be immune from liability because a submerged oil drum that a diver struck when he dived into a river was not a “natural” condition. Ibid. During that same year, the Law Division also held that a municipality would not be immune from liability to a swimmer who was injured by a body surfer, finding that the presence of the surfer in the waves was no more a natural condition than an oil drum in a river. Kleinke v. City of Ocean City, 163 N.J.Super. 424 (1978), overruled on other grounds, Sharra v. City of Atlantic City, 199 N.J.Super. 535 (App.Div.1985).
In contrast, the Appellate Division has rejected the contention that the State’s immunity is limited to injuries caused by “natural” conditions. In Freitag v. Morris County, 177 N.J.Super. 234 (1981), the Appellate Division granted summary judgment in favor of the county for injuries sustained by the plaintiff in a tobogganing accident on a county recreation area. Half of the area contained a golf course, and the other half was woodlands and open fields. The hills on which plaintiffs were tobogganing had been cleared of rocks, which had been placed alongside the hill. Plaintiffs lost control of their toboggan and crashed into the rocks. Plaintiffs contended that because the row of rocks was placed there when the hill was cleared, their *268injury was not attributable to a “natural” 'Condition. The court held that the hill had not lost its unimproved character merely because it had been cleared, and that the county was immune from liability. The Appellate Division observed that the Law Division in Diodata, supra, had incorrectly relied on interpretations of California’s immunity statute, which confers immunity only when an injury is caused by a “natural condition of any unimproved public property,” noting that N.J.S.A. 59:4-8 affords immunity for injuries caused by any condition of unimproved public property. Id. at 238 (quoting Cal. Gov’t Code § 831.2 (West)).
Accordingly, the Freitag court concluded that the determinative question in deciding
the applicability of N.J.S.A. 59:4-8 is whether the property is unimproved. Whether the injury was caused by a natural or "artificial” hazard would be relevant only insofar as it aids the court in determining the nature of the property. This approach more realistically implements the Legislature’s intention to encourage public entities to permit citizens to use unimproved public property by immunizing the public entity from tort liability. A public entity should not have to expend tax money to make unimproved property safe, even if such property has dangerous artificial conditions. Liability might attack if the public entity decides to improve the property, the rationale being that once substantial sums are expended to improve property it is not unreasonable to require the expenditure of lesser sums for safe maintenance, including the removal of hazardous artificial or natural conditions. [Id. at 238-39 (emphasis added).]
Professor Arvo Van Alstyne, who served as a consultant to the Commission that drafted the California Tort Claims Act of 1963, Cal. Gov’t Code §§ 810 to 946, and to the New Jersey Attorney General’s Task Force on Sovereign Immunity, offers an analysis similar to that of the Appellate Division in Freitag. He observes that property loses its “unimproved” status when there is “some form of physical change in the condition of the property at the location of the injury, which justifies the conclusion that the public entity is responsible for reasonable risk management in that area.” A. Van Alstyne, California Government Tort Liability Practice § 3.42 (1980) (hereinafter Van Alstyne).
*269The California courts offer an additional clarification of the term “unimproved public property.” Under their rulings, an improvement of a portion of public property does not remove the immunity from the unimproved areas. Geffen v. County of Los Angeles, 197 Cal.App. 3d 188, 192, 242 Cal.Rptr. 492, 496 (1987); Rendak v. State, 18 Cal.App. 3d 286, 288, 95 Cal.Rptr. 665, 667 (1971); accord Fuller v. State, 51 Cal.App. 3d 926, 932, 125 Cal.Rptr. 586, 592 (1975). As the California Court of Appeals observed in Rendak v. State, supra:
Appellants’ argument would demolish the immunity as to an entire park area improved in any way * * *. An entrance gate, a parking area adjoining it, or residential provision for park employees would wholly destroy the immunity. * * * It follows that improvement of a portion of a park area does not remove the immunity from the unimproved areas. [18 Cal.App. 3d at 288, 95 Cal.Rptr. at 667.]
Thus, under the California decisions, a holding that the Union Lake Dam is “improved” public property would not foreclose the statutory immunity from applying to Union Lake and the balance of the 4,300-acre preserve.
We note, however, that the Appellate Division apparently assumed that the entire tract had to be viewed as a unit, thereby precluding the court from treating the dam as an improvement while simultaneously preserving the “unimproved” character of the remaining acreage.
Clearly, the dam is a necessary and integral part of the lake and thus cannot be considered, as urged by plaintiffs, as a separate and distinct parcel of the State-owned land having no relationship to the unimproved aspect of the entire tract. In comparing the nature and extent of this man-made improvement with the nature and extent of the lake itself it is evident that the existence of the dam cannot detract from the overall unimproved character of this portion of the Union Lake Wildlife Management Area. [222 N.J. at 426.]
III.
In the context of the public policies underlying the statutory immunity for unimproved public property, it is not difficult to identify the factors that determine when property is improved to an extent sufficient to eliminate the immunity. Public property is no longer “unimproved” when there has been substan*270tial physical modification of the property from its natural state, and when the physical change creates hazards that did not previously exist and that require management by the public entity. See Van Alstyne, supra, at § 3.42; Freitag, supra, 177 N.J.Super. 234. Obviously, in order for liability to be imposed on the public entity there must be a causal connection between the “improvement” and the alleged injury. Cf. Keyes v. Santa Clara Water Dist., 128 Cal.App. 3d 882, 180 Cal.Rptr. 586 (1982) (where plaintiff struck submerged object while swimming in man-made lake created by dam, public entity retains immunity based on unimproved public property in absence of causal nexus between dam and hazardous condition that caused injury).
Whether the improvement was made before or after the property was acquired by the public entity should be of no consequence in determining the applicability of the immunity. Had the State constructed Union Lake Dam after it acquired this wildlife-recreational area in 1982, the State undoubtedly would acknowledge that the dam was an improvement it was obligated to maintain.
Union Lake Dam, although built long before the State acquired the tract in question, constitutes a substantial physical modification of the property’s natural condition. Over 2,000 feet long, with a 200-foot wide spillway, the dam impounds the Maurice River and creates Union Lake. It would be a contradiction in terms to characterize this dam as “unimproved” public property.
More to the point, as confirmed by the technical manuals on dam construction and safety, dam spillways pose special hazards to recreational boaters, as well as to downstream property owners, who risk flood damage in the event of spillway failure. See Bureau of Reclamation, U.S. Dep’t of the Interior, Design of Small Dams 507 (3d ed. 1987) (“Logbooms or boatbooms should be maintained upstream of the spillway inlet channel to prevent plugging of the spillway and to keep boats from *271entering the spillway.”); 3 J. Justin, J. Hinds & W. Creager, Engineering for Dams 663 (1945) (“An earth dam should be designed with the spillway capacity so great that there is no danger of overtopping * * *. Many earth dams are in use that have spillways of insufficient capacity to care for floods, which are certain to come sooner or later.”). History also provides examples. See Torrent of History, N.Y. Times, May 31, 1989, at A22, col. 1 (recounting the failure on May 31, 1889, of an earthen dam on South Fork Creek outside of Johnstown, Pennsylvania, which unleashed “a torrent that swept away 2,209 lives” and is regarded as “the worst such disaster in U.S. history,” and further recounting the view expressed by the editor of the Johnstown Tribune: “We think we know what struck us, and it was not the hand of Providence. Our misery is the work of man.”). In addition, a number of reported federal-court decisions illustrate the hazard posed to boaters by dam spillways. See, e.g., James v. United States, 760 F.2d 590 (5th Cir.1985); Dye v. United States, 210 F.2d 123 (6th Cir.1954); Empire Dist. Elec. Co. v. Rupert, 199 F.2d 941 (8th Cir.1952); Clark v. Tennessee Valley Auth., 606 F.Supp. 130 (N.D.Ala.1985); Russell v. Tennessee Valley Auth., 564 F.Supp. 1043 (N.D.Ala.1983).
Thus, to the extent that the degree of hazard posed by a physical alteration of property is material to a determination whether that alteration should be classified as “improved” property, it is apparent that large dams pose a hazard to safety sufficient to require a public entity to assume responsibility for their operation and maintenance. Plaintiff alleges in her complaint and affidavits opposing summary judgment that because of the configuration of the Union Lake Dam spillway, at high-water levels the flow velocity near the spillway created a “dangerous condition” for small fishing boats. It remains to be seen whether plaintiff can prove her contentions at trial. It is self-evident, however, that the “dangerous” condition of the spillway that allegedly caused the injuries in this case would not have existed had the dam not been built, and assuming its *272existence, it is the type of hazard that warrants management and remediation by the responsible public entity. Despite the State’s assertion of immunity in this litigation, it is highly unlikely that State officials assumed that the State could have acquired this 4,300-acre wildlife preserve without assuming complete responsibility for maintenance, hazard-control, and the structural integrity of Union Lake Dam. In answers to interrogatories the State acknowledged that it made comprehensive semi-annual inspections of the dam and twice-daily inspections of the spillway during the summer.
We therefore conclude, in the context of the State’s summary-judgment motion and the plaintiff’s responsive allegations, that Union Lake Dam is not unimproved public property. Hence, the State is not immunized from liability if plaintiff presents evidence that the dam and its spillway constituted a “dangerous condition” and that otherwise meets the requirements of N.J.S.A. 59:4-2. Moreover, our determination that the Act’s unimproved-property immunity does not apply to the dam itself is entirely compatible with the legislature’s avowed purpose of encouraging the public to use unimproved recreational property at its own risk. Consistent with the legislature’s objectives, we specifically adopt the holding of the California cases that recognize that public property may be partly improved and partly unimproved. Supra at 269. Thus, our holding that Union Lake Dam is “improved” property would not foreclose the statutory immunity from applying to Union Lake and the balance of the 4,300-acre preserve.
IV.
As previously noted, plaintiff first raised the issue of negligent supervision of boating activities by State employees in her brief opposing the State’s motion for leave to appeal, although no such allegations appear in the complaint. Notwithstanding this procedural irregularity, the Appellate Division observed that “the routine patrols of the conservation officers *273were directed to enforcement of the applicable laws and regulations,” concluding that there was no proof in this record “that State employees undertook the supervision of the recreational use of the lake.” 222 N.J.Super. at 427. The controlling principle is that a public entity is not liable for the failure to supervise, but only for negligent supervision. Consequently, a public entity does not lose its immunity without some employee conduct,
no matter how minute, evidencing an intention to supervise by way of monitoring, entering into or becoming a part of the activity itself from which the injury sprang. Liability for negligent supervision will not be imposed simply because there was an incidental undertaking at the same place only tangentially related to the recreational activity. [Morris v. City of Jersey City, 179 N.J.Super. 460, 464 (App.Div.1981).]
Given the procedural posture in which this issue is presented, we consider it to be inappropriate for summary disposition. The claim of negligent supervision was not alleged in the complaint and was only tangentially developed in the abbreviated record before us. Its eventual resolution by the trial court on a more developed record would better serve the interests of justice.
As noted, the Appellate Division made no determination concerning the applicability of the Landowner’s Liability Act, N.J. S.A. 2A:42A-1 to -7. Although the issue was raised in the petition for certification, the State did not address it on the assumption that the question was not before us. We express no view on its application to these facts.
The judgment of the Appellate Division is reversed and the matter remanded to the Law Division.
"High hazard" is a classification given to dams posing serious threat to public safety:
Dams impounding large reservoirs on principal rivers with high runoff potential should unquestionably be considered to be in the high-hazard category. For such developments, conservative design criteria should be selected because failure could involve the loss of life or damages of disastrous proportions. Conversely, small dams built on isolated streams in rural areas where failure would neither jeopardize human life nor create damages beyond the sponsor’s financial capabilities may be considered to be in a low-hazard category. [Bureau of Reclamation, U.S. Dep’t of the Interior, Design of Small Dams 339-40 (3d ed. 1987).]
The federal government has rated ninety-one publicly-owned and ninety-six privately-owned New Jersey dams as “high-hazard" structures. The Star Ledger, May 10, 1989, at 1, col. 1.