IN THE SUPREME COURT OF 

CALIFORNIA

CITY OF OROVILLE,

Petitioner,

v.

THE SUPERIOR COURT OF BUTTE COUNTY,

Respondent;

CALIFORNIA JOINT POWERS RISK MANAGEMENT 

AUTHORITY et al.,

Real Parties in Interest.

S243247

Third Appellate District

C077181

Butte County Superior Court

152036

August 15, 2019

Justice Cuéllar authored the opinion of the Court, in which 

Chief Justice Cantil-Sakauye and Justices Chin, Corrigan, Liu, 

Kruger, and Groban concurred.
1

CITY OF OROVILLE v. SUPERIOR COURT

S243247

Opinion of the Court by Cuéllar, J.

A dental practice suffered damage when raw sewage 

began spewing from the toilets, sinks, and drains of its building. 

The resulting damage triggered the inverse condemnation 

claim — an action to recover damages for injuries to private

property caused by a public improvement –– at the heart of this 

case. The dentists contend the City of Oroville (the City) is 

legally responsible for the property damage, because it was 

caused by the sewer system’s failure to function as intended. 

According to the dentists, the failure was manifest when the

system allowed sewage to back up into their building instead of 

siphoning the waste away from their private property. The City 

maintains the damage occurred because the dentists failed to 

install a legally-required backwater valve that would have 

prevented sewage from entering their building in the event of a 

sewer main backup. 

What we conclude is that the Court of Appeal erred in 

finding the City liable in inverse condemnation. The appellate 

court reached this decision without addressing a fundamental 

question: whether the inherent risks associated with the sewer 

system –– as deliberately designed, constructed, or 

maintained –– were the substantial cause of the damage to the

private property. 

Public entities are not strictly or otherwise automatically 

liable for any conceivable damage bearing some kind of 
CITY OF OROVILLE v. SUPERIOR COURT

Opinion of the Court by Cuéllar, J.

2

connection, however remote, to a public improvement. To 

succeed on an inverse condemnation action, a plaintiff must 

ordinarily show — assuming the public entity made reasonable

assumptions about the public improvement in question –– that

the damage to private property was substantially caused by 

inherent risks associated with the design, construction, or 

maintenance of the public improvement. That’s certainly not 

something the dentists were able to show in this case, where

installation of a backwater valve on their premises not only 

would have prevented or drastically mitigated the risk of 

damage, according to experts, but was legally required. Under 

the circumstances, the City is not liable in inverse 

condemnation, so we reverse the judgment of the Court of 

Appeal.

I.

Raw, untreated sewage from the City of Oroville’s sewer 

main backed up into a private sewer lateral in December 2009, 

invading the sinks, toilets, and drains of a local office building. 

Located at 3579 Oro Dam Boulevard, the building was owned by 

three dentists doing business as WGS Dental Complex. The 

dentists, individually and doing business as WGS Dental 

Complex (collectively WGS), filed claims against their insurer, 

The Dentists Insurance Company (TDIC). WGS sued the City 

for inverse condemnation (Cal. Const., art. I, § 19) and nuisance 

for losses it claimed were not covered by insurance. And TDIC 

filed a complaint in intervention for negligence, nuisance, 

trespass, and inverse condemnation. The City filed a cross 

complaint against WGS for its failure to ensure a backwater 

valve was properly installed on their private sewer lateral, 

alleging violation of the Oroville Municipal Code, public 

nuisance, strict liability, and negligence. 
CITY OF OROVILLE v. SUPERIOR COURT

Opinion of the Court by Cuéllar, J.

3

The City moved for summary judgment on WGS’s claims, 

citing WGS’s failure to install the backwater valve. WGS 

opposed the City’s motion, asserting it had no role in 

constructing the building and was unaware of any issue with the 

backwater valve until the sewage backed up into the building

and alleging the City’s intentional plan of maintenance of the 

sewer main allowed a blockage to form. The trial court denied 

the City’s motion, and stated, “[I]t appears that either 

prevention of the blockage or installation of the backflow 

prevention device could have prevented the damage. The 

relative importance of these two factors in causing the damage 

will be something for the trier of fact to decide.”

WGS then sought judicial determination of the City’s 

liability for inverse condemnation under Code of Civil Procedure 

section 1260.040 (section 1260.040), deferring the issue of 

damages.

1

 After WGS and the City reasserted the positions 

advanced at summary judgment, the trial court took judicial 

notice of most of the documents submitted in the summary 

judgment proceedings. On July 25, 2014, the trial court found 

the City liable in inverse condemnation. 

The City presented evidence that the sewer on Oro Dam 

Boulevard was built and operates as a gravity-driven system, in 

 

1

In Weiss v. People ex rel. Dept. of Transportation (2018) 20 

Cal.App.5th 1156, review granted June 13, 2018, S248141, we 

granted review to address whether section 1260.040 may be 

properly used in inverse condemnation proceedings to 

determine –– in advance of a bench trial –– whether a taking or 

damaging of private property has occurred. That question is not 

in dispute here, so we need not decide in this case whether a

section 1260.040 motion is a proper way to seek judicial 

resolution of an inverse condemnation claim. 
CITY OF OROVILLE v. SUPERIOR COURT

Opinion of the Court by Cuéllar, J.

4

which sewage flows downhill to a sewage treatment plant. 

Manholes provide points of access to the sewer main for 

maintenance and the sewer system is designed for sewage to

escape through the manhole immediately upstream of a sewer 

main line blockage. WGS’s private lateral sewage line connects 

to the main sewer line between manhole numbers JJ-10 and JJ11. The City found evidence of a partial blockage in the sewer 

line between manholes JJ-10 and JJ-11 on December 29, 2009, 

the date of the sewage backup into the WGS building. 

The City also submitted evidence that it enacted Oroville 

Ordinance No. 1450 in 1984, which adopted the 1982 Uniform 

Plumbing Code. This ordinance required property owners to 

install backwater valves on private sewer laterals where the 

fixtures on the property are lower than the elevation of the next 

upstream manhole of the public sewer. Backwater valves are 

installed to prevent sewage from entering buildings during 

sewer main line backups. WGS acquired its building when it 

was under construction in 1985, after the City enacted Oroville 

Ordinance No. 1450. In 1986, the City inspected the 

construction and issued a “Certificate of Occupancies” to the 

dentists. At the time of the sewage backup, WGS had no 

backwater valve installed on its private sewer lateral. 

According to the City’s experts, the sewage that backed up in 

the sewer line between manholes JJ-10 and JJ-11 would have 

ordinarily spilled out of the next upstream manhole. Instead, 

on December 29, 2009, the sewage exited through the sink and 

toilet fixtures at WGS’s offices because WGS had no backwater

valve on its private sewer lateral. 

WGS offered its own expert testimony. Its expert 

conceded that the sewage backup incident could have been 

averted if a fully functional backwater valve had been installed 
CITY OF OROVILLE v. SUPERIOR COURT

Opinion of the Court by Cuéllar, J.

5

on WGS’s building. This expert further testified that backwater

valves don’t always work to perfection, because certain 

backwater valves can be inadvertently damaged during routine 

sewer cleaning, diminishing the valve’s capacity.

After considering the evidence, the trial court found that 

WGS submitted sufficient evidence to establish the following 

facts: there was a blockage in the City’s sewer main; the 

blockage was most likely caused by roots; the blockage resulted 

in sewage backup in WGS’s offices; and the backup caused 

damage to WGS’s property. The trial court stated these basic 

facts were not in dispute, and the only issue for determination 

on the section 1260.040 motion was the legal responsibility for 

the damage that resulted from the sewage backup. 

The court then concluded that an inverse condemnation 

had occurred even though the City shared causal responsibility 

for the damage with WGS. The “primary cause of the blockage,”

the court found, was root intrusion in the sewer main and “a 

significant secondary cause of the damage” was WGS’s failure to 

install a backwater valve on their private sewer lateral, “a

necessary part of the sewer design and plan.” Citing California 

State Automobile Assn. v. City of Palo Alto (2006) 138 

Cal.App.4th 474 (City of Palo Alto), the trial court held it was 

constrained to find the City liable in inverse condemnation 

because one of the causes of damage was root blockage, which 

was described in City of Palo Alto as an inherent risk of sewer 

operation. 

Petitioning the Court of Appeal for a peremptory writ of 

mandate, the City presented three arguments. First, the 

deliberate design and construction of the sewer system was not 

the cause of the damages. Second, WGS’s failure to install and 
CITY OF OROVILLE v. SUPERIOR COURT

Opinion of the Court by Cuéllar, J.

6

maintain the legally required backwater valve defeated the 

deliberate design and construction of the sewer system. And 

third, the City claimed to have acted reasonably in operating 

and maintaining its sewer system. 

WGS argued that the trial court was correct in finding the 

City liable in inverse condemnation. TDIC assigned its 

intervention rights to the California Joint Powers Risk 

Management Authority (the Authority), a risk-sharing pool 

comprised of public entities, including the City of Oroville. 

Appearing as a real party in interest, the Authority argued that 

although recovery for inverse condemnation would be in its 

financial interest in this case, it supported the City’s position 

that inverse condemnation should not be available where 

sewage overflows onto private property because the landowner 

failed to have a backwater valve as required by law. 

The Court of Appeal concluded that the trial court had 

correctly found the City liable in inverse condemnation. First, 

the Court of Appeal addressed the City’s argument that the only 

reason sewage spilled into WGS’s private property was WGS’s 

failure to install and maintain a backwater valve, which 

defeated the design of the sewer system. Relying on City of Palo 

Alto, the Court of Appeal stated that in order to absolve itself of 

liability, the City would have to prove that other forces alone 

produced the injury. The Court of Appeal reasoned that, despite

the City’s argument to the contrary, a distinction existed

between concluding that the backwater valve had the capacity

to prevent the sewage backup from entering WGS’s private 

property, and finding the absence of the backwater valve ––

alone –– produced the injury. The Court of Appeal rejected the 

City’s argument that the absence of the backwater valve 

assuaged or eliminated its liability, characterizing it as 
CITY OF OROVILLE v. SUPERIOR COURT

Opinion of the Court by Cuéllar, J.

7

reminiscent of a “sort of contributory negligence theory from tort 

law,” in which WGS’s conduct would preclude recovery from the 

City — a concept the Court of Appeal noted was no longer 

applicable even in tort law. Again relying on City of Palo Alto,

the Court of Appeal concluded that even where an independent 

force contributes to the plaintiff’s injury, the public 

infrastructure in question is a concurrent cause if the injury 

occurred in substantial part because the improvement failed to 

function as intended. The Court of Appeal reasoned that WGS’s 

“failure to install a backup valve did not cause the blockage in 

City’s sewer main.” 

Then the Court of Appeal turned to whether the sewer, as 

deliberately designed, caused damage to private property. The 

Court of Appeal stated that the City’s sewer system was 

designed and constructed to overflow, if necessary, at the next 

upstream manhole and that the City acknowledged a sewer 

blockage was an inherent risk of the sewer system. But the 

Court of Appeal dismissed the City’s argument that there was 

no inherent risk of backup into private property if the property 

owner installed a backwater valve, noting that if the backwater 

valve was a necessary component of the sewer design, perhaps 

the City should have ensured compliance with the law. The 

Court of Appeal concluded that WGS’s failure to install the 

backwater valve did not defeat the inverse condemnation claims

and affirmed the trial court’s decision. 

We granted review to address whether the City is liable in 

inverse condemnation where sewage backs up onto private 

property because of a blockage in the City’s sewer main and the 

absence of a backwater valve that the affected property owner 

was legally required to install and maintain.
CITY OF OROVILLE v. SUPERIOR COURT

Opinion of the Court by Cuéllar, J.

8

II.

A.

Sometimes the well-being of the public justifies the seizure 

of privately held property. But in our system of government,

such private property “condemnation” for public use can only 

occur subject to certain conditions. Under article I, section 19 of 

the California Constitution (article I, section 19), a public entity 

must pay the owner just compensation when it takes or damages 

private property for public use. (Art. I, § 19, subd. (a) [“Private 

property may be taken or damaged for a public use and only 

when just compensation . . . has first been paid to . . . the 

owner”].) Used responsibly, the government’s capacity to 

condemn private property for public use allows for a reasonable 

compromise between the public good and the protection of 

private citizens whose property is needed to advance that good. 

(City of Oakland v. Oakland Raiders (1982) 32 Cal.3d 60, 64.) 

This “just compensation” clause in the California 

Constitution applies to the state’s exercise of its eminent domain 

power, constraining it by requiring that when the state takes 

private property for public use, the private property owner is 

justly compensated. (Customer Co. v. City of Sacramento (1995) 

10 Cal.4th 368, 376-377 (Customer Co.).) Where government 

does not recognize that a particular circumstance amounts 

functionally to a taking for public use or otherwise fails to pay 

the requisite compensation for the property in question, the 

property’s owner can, as here, pursue an “inverse 

condemnation” action. (See id. at p. 377; see also Locklin v. City 

of Lafayette (1994) 7 Cal.4th 327, 362.) So article I, section 19 

provides the basis for two kinds of actions: a conventional 

eminent domain proceeding, instituted by a public entity to 
CITY OF OROVILLE v. SUPERIOR COURT

Opinion of the Court by Cuéllar, J.

9

acquire private property for public use; and an inverse 

condemnation action, initiated by a private property owner 

seeking compensation for a taking or damage to his or her 

property. (Customer Co., at pp. 376-377.) 

To resolve inverse condemnation claims and the causal 

questions they raise, courts have garnered insights from tort 

and property law doctrines relevant to analogous disputes 

between private parties. (See Bunch v. Coachella Valley Water 

Dist. (1997) 15 Cal.4th 432, 439 (Bunch), citing Belair v. 

Riverside County Flood Control Dist. (1988) 47 Cal.3d 550, 562 

(Belair).) Supporting this approach was an understanding that

inverse condemnation is not a distinct cause of action, but 

instead a remedy for an already-existing cause of action. At one 

point, courts had limited inverse condemnation only to 

circumstances where a private party would be liable to the 

property owner for the injury. (Bunch, at p. 439; Belair, at p. 

562; Albers v. Los Angeles County (1965) 62 Cal.2d 250, 256 

(Albers).) We subsequently clarified that ultimately, the just 

compensation clause is the “distinct constitutional source” that 

underlies a public entity’s responsibility to compensate owners 

for those damages to private property resulting from the 

construction of a public improvement. (Holtz v. Superior Court

(1970) 3 Cal.3d 296, 302 (Holtz).) Common law doctrines may 

offer a useful analogy, but the roots of inverse condemnation 

liability lie in constitutional terrain rather than the common 

law. 

Given the constitutional roots and broad purposes 

associated with inverse condemnation claims, it is no surprise 

these can arise in a wide variety of contexts. A “deliberate 

action” undertaken by a public entity “in furtherance of public 

purposes” –– including, of course, a public improvement such as 
CITY OF OROVILLE v. SUPERIOR COURT

Opinion of the Court by Cuéllar, J.

10

a water system or a flood control levee –– can conceivably trigger 

an inverse condemnation action. (Clement v. State Reclamation 

Board (1950) 35 Cal.2d 628, 641 (Clement).) From underground 

excavation projects, to street construction, to the distinctive

realm of flood control improvements, our inverse condemnation 

law covers the proverbial waterfront of public improvements. 

(See Bunch, supra, 15 Cal.4th 432; Belair, supra, 47 Cal.3d 550; 

Holtz, supra, 3 Cal.3d 296; Bacich v. Board of Control (1943) 23 

Cal.2d 343 (Bacich).) Consistent across our assessment of these 

varied public works is the expectation that if an improvement is 

“inherently dangerous to private property,” the public entity —

by virtue of the constitutional provision — undertakes the 

responsibility “to compensate property owners for injury to their 

property arising from the inherent dangers of the public 

improvement or originating ‘from the wrongful plan or character 

of the work.’ ” (House v. L. A. County Flood Control Dist. (1944) 

25 Cal.2d 384, 396 (House).)

What makes it a challenge to set the precise limits of a 

public entity’s responsibility in practice is that multiple 

concerns, some arguably in tension with each other, are at stake 

in the interpretation of article I, section 19. One is to pool the 

burden to the individual property owner and distribute 

throughout the community the losses resulting from the public 

improvement. (Bunch, supra, 15 Cal.4th at p. 440; Holtz, supra,

3 Cal.3d at p. 303; Albers, supra, 62 Cal.2d at p. 263.) Another

is to mitigate concerns that “compensation allowed too liberally 

will seriously impede, if not stop, beneficial public 

improvements because of the greatly increased cost.” (Bacich, 

supra, 23 Cal.2d at p. 350; see also Holtz, supra, at pp. 303-304; 

Albers, supra, 62 Cal.2d at p. 263.) Indeed, the parties’ positions 

in this very case aptly illustrate how these concerns diverge. 
CITY OF OROVILLE v. SUPERIOR COURT

Opinion of the Court by Cuéllar, J.

11

WGS argues the City should be held liable in inverse 

condemnation, which would result in the cost of WGS’s losses 

being spread across the entire community. The City and the 

Authority assert that the damages were caused by WGS’s failure 

to install and maintain the required backwater valve. They 

maintain that if courts find public entities liable for damages 

resulting from private property owners’ unlawful acts or failures

to act, such entities will be discouraged from providing essential

public works projects.

In advancing these competing positions, the parties focus 

on different aspects of the inverse condemnation analysis, each 

emphasizing a distinct concept drawn from our case law. We 

have previously held that “any actual physical injury to real 

property proximately caused by [a public] improvement as 

deliberately designed and constructed is compensable under 

[the California Constitution] whether foreseeable or not.” 

(Albers, supra, 62 Cal.2d at pp. 263-264.)2 We later recognized 

the potential confusion presented in Albers by our use of the 

term “proximate cause” — which in tort law is often defined 

largely in terms of foreseeability — in a case where the damage 

was not foreseeable, yet we still imposed inverse condemnation 

 

2 The two exceptions to the “strict liability rule” recognized 

in Albers were circumstances where the urgency or importance 

of the government conduct was so overriding that public policy 

advised against holding the government liable in inverse

condemnation absent fault. (Holtz, supra, 3 Cal.3d at pp. 304-

305; Bunch, supra, 15 Cal.4th at pp. 440-441.) The first 

addressed damages inflicted in the proper exercise of the 

government’s police power; the second “occurred in the ‘unique’ 

context of water law.” (Bunch, at p. 441, citing Archer v. City of 

Los Angeles (1941) 19 Cal.2d 19, 24-25.)
CITY OF OROVILLE v. SUPERIOR COURT

Opinion of the Court by Cuéllar, J.

12

liability. (Holtz, supra, 3 Cal.3d 296, 304, fn. 9.) To mitigate 

confusion, we restated this test to eschew the term “proximate.” 

What we used instead was the term “ ‘ “substantial” causation.’ ” 

(Belair, supra, 47 Cal.3d at p. 559, quoting Holtz, supra, 3 Cal.3d 

at p. 304, fn. 9.) 

Applying this concept of “substantial causation,” we have 

explained in our inverse condemnation decisions that private 

landowners may establish inverse condemnation liability even 

where the public improvement as deliberately designed, 

constructed, and maintained was only one of several concurrent 

causes –– provided the causal nexus between the risks inherent 

in the public improvement and the harm in question was 

sufficiently robust to create a pronounced likelihood of damage. 

(Customer Co., supra, 10 Cal.4th at p. 382 [“ ‘[t]he destruction 

or damaging of property is sufficiently connected with “public 

use” as required by the Constitution, if the injury is a result of 

dangers inherent in the construction of the public improvement

as distinguished from dangers arising from the negligent 

operation of the improvement’ ” (quoting House, supra, 25 Cal.2d 

at p. 396 (conc. opn. of Traynor, J.))]; Youngblood v. Los Angeles 

County Flood Control Dist. (1961) 56 Cal.2d 603, 610

(Youngblood) [requiring a showing that the improvement “as 

planned and installed by defendant, would necessarily or

probably” cause the property damage].) What these decisions 

reflect is our concern not only with the deliberate design, 

construction, or maintenance of a public improvement, but also 

the nature of the causal relationship between the public work 

and the damages to private property. 

The City and the Authority argue that the Court of Appeal 

simply assumed that a blockage in the sewer main caused 

WGS’s property damage without addressing whether the 
CITY OF OROVILLE v. SUPERIOR COURT

Opinion of the Court by Cuéllar, J.

13

damages were caused by the inherent risks posed by the design, 

construction, or maintenance of the sewer system or by WGS’s 

failure to install and maintain the legally required backwater 

valve. And they assert that the sewer system design required 

WGS, like all users of the sewer system, to comply with the 

Uniform Plumbing Code and local ordinances and its failure to 

do so prevented the system from functioning as deliberately 

designed. Because the Court of Appeal did not address whether 

the extent of the causal contribution of inherent risks associated 

with the sewer system’s design (or, for that matter, its 

construction or maintenance) is sufficiently “substantial” to 

warrant inverse condemnation liability, the City posits that 

finding it liable under the circumstances would effectively 

saddle it with “strict liability,” irrespective of the nature of

inherent risks posed by the sewer system as deliberately 

designed, constructed, and maintained. Whether or not one 

understands WGS’s argument as essentially a call for 

imposition of strict liability, the heart of this dispute indeed 

concerns the analysis a reviewing court must undertake to 

resolve an inverse condemnation claim.

In contrast, WGS contends the City is liable for the 

resulting damages from the sewer backup. According to WGS,

a public improvement need only be a concurrent cause of 

damage in order for inverse condemnation liability to 

attach — so it is irrelevant to the inverse condemnation analysis 

whether WGS failed to install the required backwater valve. 

Although the trial court found that WGS’s failure to install and 

maintain that valve was “a significant secondary cause” of the 

damage (emphasis added), what matters most for WGS is that 

the trial court found blockage in the sewer main to be a 

concurrent cause of the damage. 
CITY OF OROVILLE v. SUPERIOR COURT

Opinion of the Court by Cuéllar, J.

14

B.

Our conclusion follows from what we explained in

Customer Co. and Holtz: a court assessing inverse 

condemnation liability must find more than just a causal 

connection between the public improvement and the damage to 

private property. What we hold is that the damage to private 

property must be substantially caused by an inherent risk 

presented by the deliberate design, construction, or 

maintenance of the public improvement. This approach aligns 

with how we have previously analyzed inverse condemnation 

liability cases. It also protects private property owners by 

allocating the financial losses resulting from the public 

improvement across the community and provides public entities 

with an incentive to internalize the reasonable risks of their 

public improvements. 

The concepts of “inherent risk” and “substantial 

causation” address somewhat overlapping considerations but 

play distinct roles in the analysis of inverse condemnation. And 

both must be present for a public entity to be liable. We have 

explained that a public entity’s construction of a public 

improvement is a deliberate action made “in furtherance of 

public purposes.” (Clement, supra, 35 Cal.2d at p. 641.) If 

damage to private property is substantially caused by the

inherent risks of the design or construction of a public 

improvement, a public entity must provide just compensation 

for the damage, whether it was intentional or the result of 

negligence by the public entity. (Ibid.; Bauer v. Ventura County 

(1955) 45 Cal.2d 276, 284.)

The inherent risk assessment requires a reviewing court 

to consider whether the inherent dangers of the public 
CITY OF OROVILLE v. SUPERIOR COURT

Opinion of the Court by Cuéllar, J.

15

improvement as deliberately designed, constructed, or 

maintained materialized and were the cause of the property 

damage. (Pacific Bell v. City of San Diego (2000) 81 Cal.App.4th 

596, 607 (Pacific Bell), citing House, supra, 25 Cal.2d at p. 396.) 

This inquiry operates as a preventive measure to ensure that 

not all private property damage bearing some causal 

relationship to a public improvement results in liability.

Rather, the injury to property must arise from the inherent 

dangers of the public improvement as deliberately designed, 

constructed, or maintained. (House, 25 Cal.2d at p. 396.) The 

inherent risk assessment — in line with the policy 

considerations underlying article I, section 19 — avoids openended liability by protecting public entities from liability for 

private property damage that is arguably connected to a public 

improvement but is not the result of the improvement’s inherent 

risks. (Belair, supra, 47 Cal.3d at p. 558.) 

Such risks may arise, for example, from a public entity’s 

adoption of a comparatively lower cost plan to create the public 

improvement. Faced with a panoply of other legitimate needs 

ranging from critter control to health care, a public entity might 

decide against expending additional funds or employing more 

protective measures in the construction of a project, even though 

the construction plan as adopted poses certain risks of damage 

to private property and the additional expenditures or 

protections could likely prevent that risk of damage. (See Holtz, 

supra, 3 Cal.3d at p. 310.) The public entity may reach its 

decision because the likelihood of damage is remote, but the 

expense of additional protection is great. (Ibid.) Where the 

undertaking of the project at the lower cost creates “some risk, 

however slight, of damage to plaintiffs’ property, it is proper to 

require the public entity to bear the loss when damage does 
CITY OF OROVILLE v. SUPERIOR COURT

Opinion of the Court by Cuéllar, J.

16

occur.” (Id. at pp. 310-311.) In those circumstances, private 

property owners should be compensated for the damage to their 

property resulting from the inherent risks posed by the public 

improvement as reasonably undertaken at the lower cost

because the public entity “ ‘is in a better position to evaluate the 

nature and extent of the risks of public improvement than are 

potentially affected property owners.’ ” (Id. at p. 311, quoting 

Van Alstyne, Inverse Condemnation: Unintended Physical 

Damage (1969) 20 Hastings L.J. 431, 495 (Van Alstyne).) 

Although evidence could conceivably arise to the contrary 

that might trigger further scrutiny, we presume the public 

entity acted reasonably in reaching its decision to adopt a 

particular plan of design, construction, or maintenance. (See 

Pacific Bell, supra, 81 Cal.App.4th at p. 608 [reasoning the city’s 

decision to install a system without monitoring capability may 

have been reasonable because the costs of monitoring may have 

outweighed the benefits].) This presumption acknowledges that 

we expect public agencies — as the public “locus of 

responsibility” for balancing efficiencies and costs — to proceed 

sensibly in the decision making process and avoid patently 

unreasonable assumptions in the planning of public 

improvements. (See Holtz, 3 Cal.3d at p. 311.) Yet it is 

consistent with protection of property owners, too: where 

damages are the direct consequence of the inherent risks posed 

by the public improvement, responsibility for the individual 

property owner’s loss is spread across the community benefiting 

from the public work. (See Bunch, supra, 15 Cal.4th at p. 440.) 

But useful public improvements must eventually be 

maintained and not merely designed and built. So the “inherent 

risk” aspect of the inverse condemnation inquiry is not limited 

to deliberate design or construction of the public improvement. 
CITY OF OROVILLE v. SUPERIOR COURT

Opinion of the Court by Cuéllar, J.

17

It also encompasses risks from the maintenance or continued 

upkeep of the public work. (See Bauer, supra, 45 Cal.2d at p. 

285.) A public entity might construct a public improvement and 

then entirely neglect any kind of preventive monitoring or 

maintenance for the improvement. (See Pacific Bell, supra, 81 

Cal.App.4th at pp. 599-600.) If the public entity makes a policy 

choice to benefit from the cost savings from declining to pursue 

a reasonable maintenance program, for instance, inverse 

condemnation principles command “the corollary obligation to 

pay for the damages caused when the risks attending these costsaving measures materialize.” (Id. at p. 608.) It may be sensible

in some sense for a public entity to forgo regular monitoring and 

repair and instead adopt a “wait until it breaks” plan of 

maintenance to save on the costs of imposing a monitoring 

system. But the damages that result from the inherent risks 

posed by the public entity’s maintenance plan should be spread 

to the community that benefits from lower costs, instead of 

leaving property owners adversely affected by the public entity’s 

choice to shoulder the burden alone. (Ibid.) 

A link to one of the aforementioned “inherent risks” is 

necessary, but not sufficient, for a successful inverse 

condemnation claim. The plaintiff must also establish 

substantial causation. Together, our inverse condemnation 

decisions offer a relatively clear picture of the causal 

relationship that must be shown for a claim to succeed. Liability 

depends on whether some element of physical, but-for causation 

is present to link the public improvement and the damage. The 

damage must be the “ ‘necessary or probable result’ of the 

improvement, or if ‘the immediate, direct, and necessary effect’ 

thereof was to produce the damage.” (Van Alstyne, supra, 20 

Hastings L.J at p. 436, fn. omitted, italics added.) Rather than 
CITY OF OROVILLE v. SUPERIOR COURT

Opinion of the Court by Cuéllar, J.

18

training attention on the mere presence of causation, our cases

have focused instead on whether there is proof that the damages 

“followed in the normal course of subsequent events” and were 

“predominantly” produced by the improvement. (Ibid., citing 

Youngblood, supra, 56 Cal.2d 603; Los Angeles C. Assn. v. Los 

Angeles (1894) 103 Cal. 461, 470.)

At the core of the test is the requirement that –– even in 

the case of multiple concurrent causes –– the injury to private 

property is an “inescapable or unavoidable consequence” of the 

public improvement as planned and constructed. (Van 

Alstyne, at p. 437, fn. 32.) As in the somewhat analogous tort 

law context, this test permits courts to consider a plaintiff’s act 

or omission in the chain of causation, for example, a property 

owner’s own failure to follow reasonable requirements imposed 

by the public entity to reduce the risk to the public 

improvement. (See Rest.2d Torts, § 442; see also Van Alstyne, 

at p. 437.) Accordingly, the substantial causation element of the 

analysis ensures liability is imposed only in instances where 

there is a sufficiently meaningful causal relationship between 

the damage to private property and the inherent risks posed by 

the public improvement as designed, constructed, or 

maintained. This approach avoids treating inverse 

condemnation as a species of strict or “ ‘absolute liability’ ” that 

would avoid the necessary analysis of inherent risks and 

substantial causation, frustrating the development of public 

improvements because of the increased costs to public entities. 

(Holtz, supra, 3 Cal.3d at p. 304.) 

To prevail on its claim of inverse condemnation liability, 

then, WGS must succeed under the correct legal analysis. It 

must demonstrate that the inherent risks posed by the sewer 

system as deliberately designed, constructed, or maintained 
CITY OF OROVILLE v. SUPERIOR COURT

Opinion of the Court by Cuéllar, J.

19

manifested and were a substantial cause of its property damage. 

WGS contends that an inherent risk of a sewer system is 

blockage caused by roots or foreign objects in the sewer main. 

Citing our opinion in Belair, WGS posits that the sewer system 

failed to function as intended because of the blockage, and the 

City should be held liable as the public improvement is 

connected in some manner to the damage to private property. 

Inverse condemnation liability, under WGS’s theory, attaches 

irrespective of whether the property damage could have been 

mitigated or extinguished if the affected property owner had 

installed the legally-required backwater valve.

Yet WGS misinterprets our precedent. Belair addressed 

the unique problems of flood control litigation –– arising in a 

distinctive context that bears only a limited relationship to our 

analysis of public improvements in other contexts –– through an 

inverse condemnation claim related to levees that failed to 

protect an area historically subject to flooding. (Belair, supra, 

47 Cal.3d at pp. 555-557, 560.) We concluded that despite heavy 

rainstorms contributing to the flooding, the levee was still a 

substantial concurring cause of the damages because “the 

improvement failed to function as it was intended.” (Id. at p. 

560.) This “failed to function as intended” concept was relevant 

in Belair only to eliminate natural flooding as a cause of the 

damage. (Id. at pp. 561-562.) Contrary to WGS’s contention, 

Belair did not announce a rule triggering liability in all inverse 

condemnation cases based solely on the existence of any 

conceivable causal connection between a public improvement 

and private property damage. WGS also relies on City of Palo 

Alto, which applied Belair’s “failed to function as intended” 

phrase in a sewage backup case. (City of Palo Alto, supra, 138 

Cal.App.4th at pp. 476-477, 483.) Citing Belair, the City of Palo 
CITY OF OROVILLE v. SUPERIOR COURT

Opinion of the Court by Cuéllar, J.

20

Alto court concluded that the purpose of the sewer was to carry 

wastewater away from the residence. The sewer failed to carry 

the wastewater away because of a blockage in the sewer main, 

so it “failed to function as intended” and the city should be liable 

in inverse condemnation. (Id. at p. 483.) WGS adopts this 

argument, asserting that the City’s sewer “failed to function as 

intended” because it did not carry the sewage away from the 

private property. 

If we adopted the reasoning from City of Palo Alto, as WGS 

urges, we would overlook a crucial aspect of the inverse 

condemnation inquiry. Indeed, under WGS’s analysis, liability 

for the public entity would attach whenever a public 

improvement is a concurrent cause of damage to private 

property, regardless of whether private property owners acted 

to defeat the deliberate design or construction of the 

improvement. The principles underlying article I, section 19 cut 

against this conclusion. (Bacich, supra, 23 Cal.2d at p. 350

[citing concerns that “compensation allowed too liberally will 

seriously impede, if not stop, beneficial public improvements 

because of the greatly increased cost”].) Instead, a court 

reviewing an inverse condemnation claim arising from sewage 

overflow must consider whether the damages to private 

property were the direct and necessary effect of the inherent 

risks posed by the public improvement as deliberately designed, 

constructed, or maintained. And in a case like this, a reviewing 

court must also assess whether the damages were the result of

a risk created not by the public improvement, but by the acts of 

the private property owner. A causal connection between the 

public improvement and the property damage alone is 
CITY OF OROVILLE v. SUPERIOR COURT

Opinion of the Court by Cuéllar, J.

21

insufficient to sustain a finding of inverse condemnation 

liability.3

III.

The Court of Appeal cited cases clarifying that inverse 

condemnation liability arises where a public improvement, as 

designed and constructed, presents an inherent risk of damage

that materializes and causes damage to private property. It did 

not analyze whether the City’s decision to implement a gravity 

flow sewer system that relied in part on property owners

installing and maintaining backwater valves as required by law 

constituted an inherent risk arising from the design, 

construction, or maintenance of the public improvement, and if

so, whether WGS’s damage was substantially caused by that 

inherent risk. What the Court of Appeal concluded instead is 

this: to prevail, the City must prove that other forces, with no 

connection to the design, construction, or maintenance of the 

sewer, alone produced the injury. The Court of Appeal also

rejected the City’s argument that WGS’s failure to install and 

maintain the legally required backwater valve was a sufficiently 

significant intervening cause that superseded the improvement 

in the chain of causation. By failing to analyze inverse 

condemnation with sufficient focus on substantial causation by 

inherent risks associated with the public improvement, and 

presuming that the City must disprove any causal connection to 

the harm, the Court of Appeal erred. 

 

3 To the extent it conflicts with this holding, we disapprove 

California State Automobile Assn. v. City of Palo Alto, supra, 138 

Cal.App.4th 474. To the extent it adopts the “failed to function 

as intended” concept from Belair into the sewage overflow 

context, we also disapprove. 
CITY OF OROVILLE v. SUPERIOR COURT

Opinion of the Court by Cuéllar, J.

22

At no point in these proceedings has WGS shown the 

damage to its property was substantially caused by an inherent 

risk of the City’s sewer system, as deliberately designed, 

constructed, or maintained –– nor has it given us any rationale 

to doubt that the City made reasonable assumptions in reaching 

its decision for the design, construction, or maintenance of the 

sewer system. In fact, the record supports that the City acted 

reasonably in adopting the design for the sewer system, and that 

the sewer was designed in accordance with the accepted 

practices for designing and constructing sewer systems of that

time. The trial court had before it evidence that at the time of 

the sewage backup, there was no backwater valve installed on 

WGS’s private sewer lateral and if a fully functional backwater 

valve or backflow prevention device had been installed on WGS’s 

sewer lateral, as required by law, the sewage backup incident 

could have been averted. Consider what it means to ignore the 

missing backwater valve in this case. We’d be airbrushing out 

of the picture not only the City’s considered judgment about 

what it would take to balance safety and practical 

considerations for this public improvement, but WGS’s 

noncompliance with an ordinary planning code requirement

that would have eliminated or at least mitigated risks of sewage 

backup damage. That is hardly different from turning inverse 

condemnation into a basis for automatic imposition of liability

on the public entity if even a tenuous causal connection exists 

between the public improvement and private property damage, 

irrespective of whether a plaintiff’s act or omission materially 

contributes to the risk. And it ignores that the City, like all 

public entities in an imperfect world of scarce resources, is in 

the business of weighing safety, the availability of resources, 

and possible risks that may result from its public improvements.
CITY OF OROVILLE v. SUPERIOR COURT

Opinion of the Court by Cuéllar, J.

23

So we cannot conclude that the invasion of raw sewage 

into WGS’s private property was an inherent risk of the sewer 

system as deliberately designed and constructed. Nor can we 

conclude that the backup of sewage into WGS’s offices was the 

necessary or probable result of the sewer system’s operations. 

And the City did not act unreasonably in expecting private 

property owners to comply with the law. This finding is 

consistent with the policy considerations underlying article I, 

section 19, because WGS, if uncompensated, will not contribute 

more than its proper share to the public undertaking. The 

damage to its property could have been averted had WGS 

installed the backwater valve, and so the loss suffered by WGS 

should not be distributed throughout the community. We find 

the City is not liable in inverse condemnation for the damage to 

WGS’s private property. 

IV.

When public improvements damage private property, 

property owners not compensated earlier may seek recovery 

through inverse condemnation claims. But to succeed, such

claims must demonstrate more than just a causal 

link — however tenuous — between the existence of the public 

improvement and the property damage. Instead, inverse 

condemnation liability depends on whether the property 

damage was the probable result or necessary effect of an

inherent risk associated with the design, construction, or 

maintenance of the relevant public improvement.

The damage to WGS’s property arguably bears some 

connection to the design, operation, and maintenance of the 

sewer system: the sewage passed through the system before 

emerging in the dentist’s office, and it was perhaps possible in 
CITY OF OROVILLE v. SUPERIOR COURT

Opinion of the Court by Cuéllar, J.

24

principle to design a sewage system that made backwater valves 

entirely redundant. Yet we cannot say the damage was

substantially caused by that system when WGS failed to fulfill

a responsibility to install a backwater valve, and that 

reasonable requirement would have prevented or substantially 

diminished the risk of the mishap that spawned this case. The

backup of sewage into WGS’s offices was not the necessary 

result or unavoidable consequence of any risk posed by the 

sewer system. And the City acted reasonably in adopting the 

sewer design and presuming private property owners would 

comply with the law by installing and maintaining backwater 

valve devices to prevent sewage backups into private property. 

The City is not liable in inverse condemnation. We reverse the 

judgment of the Court of Appeal and vacate its order denying 

the petition for writ of mandate and direct the Court of Appeal 

to remand this case to the superior court for further proceedings 

consistent with this opinion.

CUÉLLAR, J.

We Concur:

CANTIL-SAKAUYE, C. J.

CHIN, J.

CORRIGAN, J.

LIU, J.

KRUGER, J.

GROBAN, J.
See next page for addresses and telephone numbers for counsel who argued in Supreme Court.

Name of Opinion City of Oroville v. Superior Court

__________________________________________________________________________________

Unpublished Opinion XXX NP opn. filed 6/13/17 – 3d Dist.

Original Appeal

Original Proceeding

Review Granted

Rehearing Granted

__________________________________________________________________________________

Opinion No. S243247

Date Filed: August 15, 2019

__________________________________________________________________________________

Court: Superior

County: Butte

Judge: Sandra L. McClean

__________________________________________________________________________________

Counsel:

Peters, Habib, McKenna & Juhl-Rhodes, Mark A. Habib, Lia M. Juhl-Rhodes; Colantuono, Highsmith & 

Whatley, Michael G. Colantuono, Jennifer L. Pancake; Cota Cole & Huber, Cole Huber and Scott E. Huber 

for Petitioner.

Michael N. Feuer, City Attorney (Los Angeles), Blithe Smith Bock and Timothy McWilliams, Assistant 

City Attorneys, for League of California Cities, California Joint Powers Insurance Authority, Public Entity 

Risk Management Authority, California Special Districts Association, California Association of Joint 

Powers Authorities and California Sanitation Risk Management Authority as Amici Curiae on behalf of 

Petitioner.

No appearance for Respondent Superior Court.

Gibbons & Conley, A. Byrne Conley and Peter A. Urhausen for Real Party Interest California Joint Powers 

Risk Management Authority.

Berding Weil, Jordan M. Rojas and James O. Devereaux for Real Parties in Interest Timothy G. Wall, Sims 

W. Lowry and William A. Gilbert.

Meyers, Nave, Riback Silver & Wilson, John Bakker and Kenton L. Alm for California Association of 

Sanitation Agencies as Amicus Curiae on behalf of Petitioner and Real Party in Interest.
Counsel who argued in Supreme Court (not intended for publication with opinion):

Michael G. Colantuono

Colantuono, Highsmith & Whatley

420 Sierra College Drive, Suite 140

Grass Valley, CA 95945

(530) 432-7357

Peter A. Urhausen

Gibbons & Conley

Hookston Square

3480 Buskirk Avenue, Suite 200

Pleasant Hill, CA 94523

(925) 932-3600

James O. Devereaux

Berding Weil

2175 North California Boulevard, Suite 500

Walnut Creek, CA 94596

(925) 838-2090