Shenson v. County of Contra Costa ( 2023 )


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  • Filed 3/30/23
    CERTIFIED FOR PUBLICATION
    IN THE COURT OF APPEAL OF THE STATE OF CALIFORNIA
    FIRST APPELLATE DISTRICT
    DIVISION TWO
    BRIAN SHENSON et al.,
    Plaintiffs and Appellants,           A164045
    v.                                           (Contra Costa County
    COUNTY OF CONTRA COSTA et                    Super. Ct. No. CIVMSC1701267)
    al.,
    Defendants and Respondents.
    Plaintiffs and appellants (collectively, Owners) are two couples who
    purchased residential properties in neighboring subdivisions within Contra
    Costa County (County) in 2010 and 2016. Both properties are adjacent to a
    creek. They sued the County and a flood control district (collectively,
    Government Entities) for inverse condemnation and parallel tort causes of
    action after drainage improvements the subdivision developers had
    constructed 40-plus years earlier failed and serious erosion and subsidence
    damaged Owners’ properties. Owners appeal from the judgment the superior
    court entered after granting summary judgment against them on their
    complaint.
    The parties litigated the case for about four years, completing all or
    most discovery. The Government Entities filed motions for summary
    judgment or in the alternative summary adjudication. The material facts are
    undisputed. In substance, in the mid-1970s, the County approved
    1
    subdivision maps for two subdivisions containing the parcels later acquired
    by Owners. The creek that runs along Owners’ properties is a natural
    watercourse that functions as the main receptacle for storm runoff emanating
    from the watershed above Owners’ properties and is the only reasonable
    means of collecting and conveying that runoff. Pursuant to the Subdivision
    Map Act, the County required the developers to make certain drainage
    improvements to collect and convey water from the two subject subdivisions
    as well as one adjacent subdivision, to the creek. Among the properties that
    contribute runoff to the creek by way of the improvements were three roads,
    two private roads serving as ingress and egress to the subdivisions and one
    county owned road that is adjacent to one of the subdivisions.
    As provided by the Subdivision Map Act, the County also required the
    subdivision developers to dedicate drainage easements to the County. When
    it approved the subdivision maps, however, the County did not accept the
    offers of dedication for the drainage improvements, which remained in the
    ownership of the developers and later the homeowners who purchased the
    property.
    Owners claim the County assumed ownership and responsibility for the
    drainage improvements by requiring the subdivision developers to construct
    them and to offer to dedicate easements to the County to enable it to
    maintain them. The County contends that it did not accept the offers to
    dedicate the easements and did not otherwise assume responsibility for
    maintaining them.
    Owners sued the flood control district under inverse condemnation and
    other theories, positing that its collection of drainage fees from homeowners
    in subdivisions within the watershed rendered it responsible for the drainage
    improvements constructed by the subdivision developers. The evidence
    2
    indicates the district did not fund those improvements, which preceded its
    formation. It contends it cannot be liable for merely collecting fees for future
    improvements that, thus far, have not been constructed because of the
    unavailability of matching federal funds.
    We affirm the judgment. As a matter of law, a public entity must
    either own or exercise actual control over a waterway or drainage
    improvements to render them public works for which the public entity is
    responsible. The undisputed facts here do not establish any such ownership
    or control.
    BACKGROUND
    I.
    Facts
    In the 1970s and 1980s, the County approved subdivision maps for
    minor subdivisions in then-unincorporated parts of the County. As relevant
    here, the County approved the developer’s application for a subdivision map
    for Minor Subdivision (MS) 102-72 in 1973, subject to various conditions. It
    approved the application for Subdivision 4983 in 1980, again apparently
    subject to conditions.
    Both subdivisions were bordered on one side by a tributary of a creek
    known as “Murderer’s Creek.” As the parties have done, for ease of reference
    we will refer to the tributary as “Murderer’s Creek” or “the Creek.” The
    Creek is a natural watercourse that has functioned historically as the main
    receptacle for storm water runoff emanating from the watershed upstream of
    these subdivisions. When the applications for the subdivision maps for
    subdivisions MS 102-72 and 4983 were made, the County imposed certain
    conditions relating to drainage.
    3
    One condition for approval of the MS 102-72 subdivision map was that
    the subdivision developer “construct, install and complete . . . tract drainage”
    and conduct related work and improvements “in a good, workmanlike
    manner. In accordance with accepted construction practices and in a manner
    equal or superior to the requirements of the County Ordinance Code and
    rulings made thereunder . . . .” The developer was required by county
    ordinance to collect and convey “[a]ll surface waters flowing from the
    subdivision in any form or manner” from the development to the nearest
    natural watercourse with a definable bed and banks or to a public storm
    drainage facility. The developer of MS 102-72 was required, among other
    things, to improve the channel of the Creek “to convey the peak design runoff
    for the watershed” and to provide drainage of runoff from a private cul-de-sac
    within the subdivision known as “Kelly Ann Court” via a conduit to the
    Creek.
    Some of the other drainage improvements the developer constructed
    and installed were an outfall at the Creek with a spillway to protect the bed
    and bank of the Creek against erosion from the accelerated discharge of
    surface water from the pipeline into the Creek, sidewalks, curbs, and gutters
    on Gloria Terrace, a County road adjacent to the subdivision, and a means of
    diverting and conveying surface water accumulating on that road through
    MS 102-72 to the discharge point at the Creek. At some point during the
    subdivision process, the County requested the developer’s cooperation in
    obtaining an easement within MS 102-72 for the purpose of installing a drain
    line to complete public improvements benefiting a neighboring subdivision
    (Subdivision 4234). MS 102-72 improvement plans submitted to the County
    included the “buried storm drain line” running along the western limit of the
    subdivision where it adjoined Subdivision 4234, which received runoff from
    4
    that subdivision, merged with runoff from MS 102-72 in a catch basin and
    was conveyed through an underground pipeline through MS 102-72 to the
    Creek.
    The developers of MS 102-72 (and Subdivision 4234) designed and
    constructed the improvements, not the County. However, a county ordinance
    required developers to submit plans for required improvements to the
    County’s Public Works Department for review and required the Department
    to inspect the work and, when satisfied it was complete and met county
    requirements, to recommend that the County Board of Supervisors accept the
    improvements. The limited purpose of such acceptance was to establish an
    end date for the contractor’s liability under a provision requiring it to
    guarantee performance of the work and repair of defects for a one-year period
    after acceptance.
    The Board by resolution accepted the improvements for MS 102-72 as
    “completed for the purpose of establishing a terminal period for filing liens in
    case of action under [the MS 102-72] Subdivision Agreement” in 1978. As
    also required by ordinance, the Board adopted a resolution at the end of the
    one-year period finding “the improvements have satisfactorily met the
    guaranteed performance standards for one year after completion and
    acceptance.”
    The developer was required to obtain or dedicate drainage easements to
    the County for certain drainage improvements. The parcel map for MS 102-
    72 depicts two drainage easements and a note indicating they are “dedicated
    to Contra Costa County for drainage purposes.” The actual drainage
    easement dedication language is contained in a separate document entitled
    “Offer of Dedication” that was recorded in 1975. It provided that the
    developer “being the present title owner(s) of record of the herein described
    5
    parcel of land, do hereby make an irrevocable offer of dedication to Contra
    Costa County and its successor or assign, of an easement for storm, flood and
    surface water drainage, including construction, access, or maintenance of
    works, improvements and structures, . . . or the clearing of obstructions and
    vegetation, upon the real property . . . described as follows . . . .” The
    document refers to the parcel map for the location of the easements. It
    further states, “It is understood and agreed that CONTRA COSTA COUNTY
    and its successor or assign shall incur no liability with respect to such offer or
    dedication, and shall not assume any responsibility for the offered parcel of
    land or any improvements thereon or therein, until such offer has been
    accepted by appropriate action of the Board of Supervisors, or of the local
    governing body of its successor or assign.” In December 1975, the County
    issued and recorded an order stating that the offer was “ACCEPTED for
    recording only.” (Italics added.)1
    The subdivision process for Subdivision 4983 took place a few years
    after MS 102-72 was completed. The County required the developer of this
    subdivision to make drainage improvements as well. The improvements
    appear to have been more modest and included an asbestos cement pipe
    coupled to a corrugated steel pipe storm drain to collect storm water runoff
    from Via Ferrari, a small private street within the subdivision, and carry it to
    an outlet at the Creek. The County did not design, construct or install the
    drainage improvements on Subdivision 4983. It did inspect the drainage
    plans and the improvements as required by local ordinance.
    1 Six months later, it rescinded that order because of an error in the
    subdivision number and issued and recorded a corrected order, again
    providing that the acceptance of the offer was “for recording only.”
    6
    On the subdivision map, the developer offered to dedicate two drainage
    easements to the County. The County expressly did not accept or reject the
    offer to dedicate the easements.
    There is no record of the County ever expressly accepting the offers of
    the subdivision developers for either MS 102-72 or Subdivision 4983 to
    dedicate drainage easements. There is no record of the County indicating it
    has ever performed maintenance or repair of the drainage improvements
    constructed on MS 102-72 or Subdivision 4983. Nor are there any County
    records indicating the County performed maintenance of or repairs to
    Murderer’s Creek at or upstream of the subdivisions.
    Owners purchased properties in the subdivisions three to four decades
    after the subdivision maps were approved. In 2011, Brian Shenson and
    Emily Shenson purchased real property at 1904 Via Ferrari in
    Subdivision 4983 (the Shenson Property). The Creek flows along the
    Shenson Property’s northeasterly property line. In 2016, Megan Frantz and
    David Mariampolski purchased property near the Shenson Property at
    18 Kelly Ann Court in MS 102-72 (the Frantz Property). The Creek flows
    along or near the Frantz Property’s southwesterly property line.2
    In early 2016, the spillway the developer had constructed four decades
    earlier failed and collapsed into the Creek bed. The uncontrolled discharge of
    water into the Creek caused a scour hole to form and expand, eventually onto
    the neighboring private subdivisions. Owners allege the scour hole caused
    2 Owners contend that a portion of MS 102-72 that includes part of the
    Creek where it adjoins the lot that later became the Frantz Property was
    deeded to the Pleasant Hill Park District and became part of Brookwood
    Park. The Park District is not a party to this appeal. Whether some of the
    improvements are on the Frantz Property or the Park District’s property is
    not material to this appeal.
    7
    erosion and subsidence damage to their respective properties. Owners
    contend the Government Entities are responsible for the formation of the
    scour hole because they failed to maintain the Creek’s bed and banks and
    refused to repair or replace the spillway after it failed. In 2017–2018, the
    expanding scour hole contributed to the failure of a second spillway that was
    located 20 feet north of the first spillway and had served the water discharge
    needs of Subdivision 4983.
    II.
    Complaint and Motion for Summary Judgment
    The operative third amended complaint alleged causes of action for
    inverse condemnation, trespass, nuisance and dangerous condition of public
    property.3 Owners alleged the County was responsible for the damage the
    Creek and drainage improvements caused to their properties for several
    reasons. First, the County approved subdivision MS 102-72; second, it
    required the developer of that subdivision to construct the drainage
    improvements, including a pipeline, a spillway and a catch basin; third, it
    used those facilities to discharge water from another subdivision and from
    city streets into the Creek; fourth, it required the developer to offer to
    dedicate to the County an easement over the property containing those
    improvements and portions of the bed and banks of the Creek; and fifth, it
    permitted and encouraged private development of properties upslope from
    Owners’ properties. Owners further alleged that the County accepted the
    drainage improvements from the developer, used them for public purposes,
    approved subdivision maps depicting the drainage easements and now “owns
    3  The pleading also included claims against the Pleasant Hill Park
    District. The claims against the Park District are not the subject of this
    appeal.
    8
    and controls” the land within the drainage easements. They alleged that the
    County “approved, owned, operated, controlled, repaired and/or maintained a
    public drainage system” of which the Creek is a part and that the drainage
    system caused damage to Owners’ properties.
    Owners alleged that the Contra Costa County Flood Control and Water
    Conservation District (District) incorporated the Creek into the public
    drainage system through its establishment of a statutory drainage area
    known as Drainage Area 46 that includes the Creek, Owners’ properties and
    other properties in the area. They alleged the County and District assessed
    and continue to assess “storm drainage fees” from property owners within
    Drainage Area 46 to offset the increased burden that new and expanding
    development in the area has put on the public drainage system. They further
    alleged that the District chose to hold the funds from the collected drainage
    fees to be used for a future project instead of using them to install mitigation
    measures against the increased water runoff or to repair the spillway.
    The County and the District filed motions for summary judgment or
    summary adjudication. The County argued it was not liable to Owners for
    inverse condemnation because (1) the Creek was not a public improvement
    owned or controlled by the County; (2) its acts in approving the subdivisions
    and requiring drainage improvements and offers of dedication did not
    transform the Creek into a public storm drain system or otherwise make it or
    the improvements a public work; (3) it had not accepted the offers of
    dedication of drainage easements after they were made; and (4) it had not
    made repairs or maintained the improvements or otherwise impliedly
    accepted the offers. Finally, the County argued that Owners’ related tort
    causes of action for nuisance, dangerous condition of public property, and
    9
    trespass also fail since neither the Creek nor the drainage improvements
    were public improvements owned or controlled by the County.
    The District made similar arguments. The District explained that it
    was formed in 1951 and was statutorily authorized to establish “drainage
    areas” and to “institute drainage plans for the specific benefit of such areas.”
    It argued that none of its activities, including forming Drainage Area 46
    “with the goal of implementing a regional concept-plan for flood protection to
    protect areas in the City of Pleasant Hill downstream of Taylor Blvd.,”
    adopting a Drainage Fee Ordinance, establishing a drainage facilities fund
    for that project, and requesting (but not receiving) matching federal funds,
    transformed the Creek into a District-owned or controlled public
    improvement. Further, it argued that it was not an offeree and did not
    accept the offers of dedication by the subdivision developers, did not provide
    any storm drainage services, is not a landowner in the watershed, does not
    divert flows from outside areas into the watershed, does not own any
    upstream properties or discharge any runoff into the creek, and did not use or
    otherwise impliedly accept the easements.
    In opposition to the County’s motion, Owners contended the County
    was liable for inverse condemnation because it (1) required the developer of
    MS 102-72 to install drainage improvements as a condition of approval so
    that surface water from Gloria Terrace (a County road) and a neighboring
    subdivision could be conveyed through MS 102-72 and into the Creek; (2)
    required the developer to place drainage easements over these improvements
    and dedicate them to the County; and (3) jointly with the District, exercised
    dominion and control over the Creek by requiring all property owners within
    Drainage Area 46 to discharge additional runoff caused by improvements to
    their properties into the Creek.
    10
    Owners opposed the District’s motion on grounds similar to those in its
    opposition to the County’s motion. Owners additionally argued that the
    District incorporated the Creek into the public drainage system by (1)
    creating Drainage Area 46; (2) compelling property owners who develop land
    in the watershed to use the Creek to dispose of additional storm drainage;
    and (3) collecting storm drainage fees from property owners for this use.
    As part of their oppositions, Owners submitted the declaration of
    Douglas Flett, a civil engineer. As relevant to this appeal, the declaration
    stated that if the County had intended the drainage improvements in
    MS 102-72 to be private instead of public, it would not have required the
    property owner to dedicate the drainage easements to the County for public
    use. Further, if the County had intended for the owner to maintain the
    improvements, the easements would have been conveyed to a homeowners’
    association. The expert concluded that this was “evidence that at the time of
    the creation of [MS 102-72], the parties understood that the County would
    have the maintenance obligation for the drainage system that serves the
    subdivision.” The County and the District objected to this testimony on the
    bases of lack of foundation (Evid. Code, § 403), improper expert opinion (id.,
    § 801), and speculation (id., § 801, subd. (b)).
    The trial court granted summary judgment in favor of the County and
    the District, concluding there was insufficient evidence to support the
    assertion that they exerted control over or assumed responsibility for either
    the Creek or the drainage system and that the County’s use of the Creek to
    drain surface water from county roads and to require other riparian owners
    in the watershed to do the same did not transform the Creek into a public
    drainage system. The court held that under our Supreme Court’s decision in
    Locklin v. City of Lafayette (1994) 
    7 Cal.4th 327
     (Locklin), requiring the
    11
    dedication of drainage easements as a condition precedent to subdivision
    approval “does not demonstrate [defendants’] control over a natural
    watercourse.” The undisputed evidence established that the County did not
    accept the drainage easements on the Shenson Property and accepted the
    easements on the Frantz Property for recording purposes only. The trial
    court sustained the County’s objection to a portion of Flett’s declaration.
    Nor, the court held, were the District’s acts in collecting fees from
    property owners evidence of control of the Creek or storm drain facilities.
    The fees collected were “in service of a proposed plan that has not been
    implemented.” There was no evidence that the District provided storm
    drainage services or maintained any of the easements and the court
    concluded the evidence failed to show control by the District.
    The court entered judgment in favor of the County and the District, and
    Owners timely appealed.
    DISCUSSION
    I.
    Standard of Review
    Summary judgment is proper “if all the papers submitted show that
    there is no triable issue as to any material fact and that the moving party is
    entitled to a judgment as a matter of law.” (Code Civ. Proc., § 437c,
    subd. (c).) A defendant seeking summary judgment “bears the burden of
    persuasion that there is no triable issue of material fact and that [it] is
    entitled to judgment as a matter of law.” (Aguilar v. Atlantic Richfield Co.
    (2001) 
    25 Cal.4th 826
    , 850.) A defendant meets this burden by showing that
    plaintiff “has not established, and cannot reasonably expect to establish” an
    essential element of his claim. (Saelzler v. Advanced Group 400 (2001)
    
    25 Cal.4th 763
    , 768.)
    12
    We review a grant of summary judgment de novo, which means we
    “decide independently whether the facts not subject to triable dispute
    warrant judgment for the moving party as a matter of law.” (Intel Corp. v.
    Hamidi (2003) 
    30 Cal.4th 1342
    , 1348.) In deciding whether a material issue
    of fact exists for trial, we “consider all of the evidence set forth in the papers,
    except the evidence to which objections have been made and sustained by the
    court, and all inferences reasonably deducible from the evidence.” (Code Civ.
    Proc., § 437c, subd. (c).) We view the evidence in the light most favorable to
    the plaintiffs, as the nonmoving parties, liberally construing their evidentiary
    submission while strictly construing the defendants’ own showing and
    resolving any evidentiary doubts or ambiguities in plaintiffs’ favor. (Saelzler
    v. Advanced Group 400, 
    supra,
     25 Cal.4th at p. 768.)
    II.
    Substantive Law
    A.    The Subdivision Map Act
    “The Subdivision Map Act is ‘the primary regulatory control’ governing
    the subdivision of real property in California. [Citation.] The Act vests the
    ‘[r]egulation and control of the design and improvement of subdivisions’ in
    the legislative bodies of local agencies, which must promulgate ordinances on
    the subject. ([Gov. Code,] § 66411.) The Act generally requires all
    subdividers of property to design their subdivisions in conformity with
    applicable general and specific plans and to comply with all of the conditions
    of applicable local ordinances.” (Gardner v. County of Sonoma (2003)
    
    29 Cal.4th 990
    , 996-997 (Gardner), fn. omitted.)
    “Ordinarily, subdivision under the Act may be lawfully accomplished
    only by obtaining local approval and recordation of a tentative and final map
    pursuant to [Government Code] section 66426, when five or more parcels are
    13
    involved, or a parcel map pursuant to [Government Code] section 66428 when
    four or fewer parcels are involved. [Citation.] A local agency will approve a
    tentative and final map or a parcel map only after extensive review of the
    proposed subdivision and consideration of such matters as the property’s
    suitability for development, the adequacy of roads, sewer, drainage, and other
    services, the preservation of agricultural lands and sensitive natural
    resources, and dedication issues. (See, e.g., [Gov. Code,] §§ 66451–66451.7,
    66452–66452.13, 66453–66472.1, 66473–66474.10, 66475–66478.)” (Gardner,
    
    supra,
     29 Cal.4th at p. 997.)
    “By generally requiring local review and approval of all proposed
    subdivisions, the Act aims to ‘control the design of subdivisions for the benefit
    of adjacent landowners, prospective purchasers and the public in general.’
    [Citation.] More specifically, the Act seeks ‘to encourage and facilitate
    orderly community development, coordinate planning with the community
    pattern established by local authorities, and assure proper improvements are
    made, so that the area does not become an undue burden on the taxpayer.’ ”
    (Gardner, supra, 29 Cal.4th at pp. 997-998.)
    The Act defines “[d]esign” to include, among other things, “drainage
    and sanitary facilities and utilities, including alignments and grades thereof.”
    (Gov. Code, § 66418.4) It defines “[i]mprovement” to include “any street work
    and utilities to be installed, or agreed to be installed, by the subdivider on the
    land . . . as are necessary for the general use of the lot owners in the
    subdivision and local neighborhood traffic and drainage needs as a condition
    precedent to the approval and acceptance of the final map thereof.” (§ 66419,
    subd. (a).) It has been said that “[o]ne of the main purposes of the
    4All further statutory references are to the Government Code unless
    otherwise specified.
    14
    Subdivision Map Act is to require the subdivider to install properly the
    streets and drains under the provisions of that act.” (City of Buena Park v.
    Boyar (1960) 
    186 Cal.App.2d 61
    , 67.)
    The Act provides “the key authorization for imposing conditions on
    development.” (4 Manaster & Selmi, Cal. Environmental Law and Land Use
    (2022) Subdivision Regulation (4 Manaster & Selmi) § 61.03[6] at pp. 61-28 to
    61-28.1 (rels. 51-10/2009, 60-3/2014).) “In approving subdivisions, local
    agencies require that land be dedicated for public uses, that public and
    private improvements be built, that design review fees be paid to cover the
    cost of design review, and that capital or impact fees be paid to cover the
    subdivided land’s share of the costs for a wide range of amenities.” (Id.,
    § 61.06[1] at p. 61-74.2 (rel. 76-4/2022).)
    The Act contains “provisions authorizing local agencies to impose
    specific conditions on subdivision approvals to achieve certain public
    purposes or offset particular impacts.” (4 Manaster & Selmi, supra,
    § 61.06[2] at pp. 61-74.2 to 61-74.3 (rel. 76-4/2022); see Youngblood v. Board
    of Supervisors (1978) 
    22 Cal.3d 644
    , 652 [“The Subdivision Map Act
    contemplates that the local agency, when it approves a tentative map, will
    normally attach conditions to that approval, such as the completion of
    planned subdivision improvements, and will approve the final map only after
    certifying that the subdivider has complied with those specified conditions”].)
    This includes improvements for such things as streets, utilities and drainage.
    (4 Manaster & Selmi, supra, § 61.03[6] at pp. 61-28 to 61-28.1 (rels. 51-
    10/2009, 60-3/2014).) Indeed, requiring the subdivider to install drainage has
    been described as one of “several salutary purposes” of the Act. (Pratt v.
    Adams (1964) 
    229 Cal.App.2d 602
    , 605-606.) It is typical for a subdivision
    agreement to require a subdivider to perform the work constructing
    15
    improvements in accordance with plans and specifications previously
    approved by the local agency and to require security to ensure performance of
    the work. (4 Manaster & Selmi, supra, § 61.04[9][b][ii] at pp. 61-58 to 61-59
    (rel. 38-3/03).) Another common condition is that the subdivider dedicate or
    make an irrevocable offer of dedication for such purposes such as streets,
    drainage, public utilities or public access. (See § 66475.)
    B.    Inverse Condemnation
    The primary theory asserted by Owners is based on the law of inverse
    condemnation. To understand the parties’ allegations and arguments and
    the issues in the summary judgment proceedings at the heart of this appeal,
    some background about tort and inverse condemnation law as it pertains to
    subdivisions and drainage is required.
    A public entity may be liable as a property owner when alterations or
    improvements to its own upstream property result in the discharge of an
    increased volume of or velocity of surface water in a natural watercourse
    causing damage to the property of a downstream owner. (Locklin, supra,
    7 Cal.4th at p. 337.) As with any upstream property owner, whether public
    or private, a government entity is only liable if, considering all of the
    circumstances, its conduct was unreasonable and the lower property owner
    acted reasonably. (Ibid.) Damage resulting from improvements on publicly
    owned property may also result in inverse condemnation liability. (Id. at
    pp. 337-338.)
    Further, a government entity may be liable in inverse condemnation
    where the increased volume or velocity of surface waters and resulting
    damage are caused by discharge of increased surface waters from public
    works or improvements on publicly owned land or if it has incorporated the
    watercourse or public improvements into a public drainage system. (Locklin,
    16
    supra, 7 Cal.4th at pp. 337-338.) The theory underlying inverse
    condemnation liability in these contexts is similar to that for inverse
    condemnation generally: the downstream owner “may not be compelled to
    accept a disproportionate share of the burden of improvements undertaken
    for the benefit of the public at large.” (Id. at p. 338; see also id. at p. 367;
    Belair v. Riverside County Flood Control Dist. (1988) 
    47 Cal.3d 550
    , 558
    [decisive consideration is whether owner of damaged property if
    uncompensated would contribute more than his proper share to public
    undertaking].) Similar to a tort, under inverse condemnation, the
    reasonableness of the public entity’s conduct matters. The public entity will
    be liable only “if it fails to use reasonably available, less injurious
    alternatives.” (Locklin, supra, at p. 338.) In addition, the downstream owner
    must take reasonable measures to protect his property and if he fails to do so,
    there is no liability. (Ibid.)
    “A storm drainage system constructed and maintained by a public
    entity” is a public work. (Souza v. Silver Development Co. (1985)
    
    164 Cal.App.3d 165
    , 170.) To convert an existing watercourse into a public
    work, “[a] governmental entity must exert control over and assume
    responsibility for maintenance of the watercourse if it is to be liable for
    damage caused by the streamflow on a theory that the watercourse has
    become a public work.” (Locklin, 
    supra,
     7 Cal.4th at p. 370.) The same is
    true of converting privately constructed improvements into public works.
    (Ullery v. County of Contra Costa (1988) 
    202 Cal.App.3d 562
    , 570 (Ullery).)
    “Official acts of dominion and control constituting acceptance of the private
    drainage system can be shown if the public entity does maintenance and
    repair work. [Citations.] Use of land for a public purpose over time may
    constitute implied acceptance of the offer of dedication. [Citation.] On the
    17
    other hand, where ‘there is no acceptance of a street or the drainage system
    within it, there is no public improvement, public work or public use and
    therefore there can be no public liability for inverse condemnation.’ ” (Id. at
    pp. 568-569.)
    “[I]nverse condemnation liability will not lie for damage to private
    property allegedly caused by private development approved or authorized by
    the public entity, ‘where the [public entity’s] sole affirmative action was the
    issuance of permits and approval of the subdivision map.’ ” (Ullery, supra,
    202 Cal.App.3d at p. 570.)
    III.
    Plaintiffs’ Theories on Appeal
    Owners assert three theories to support their claims of inverse
    condemnation, one as to the County only and two as to the County and the
    District jointly.
    As to the County alone, Owners claim the MS 102-72 spillway was a
    component of a drainage system that must be considered public. This is so,
    they argue, because (1) the County required the subdivider to construct it as
    a condition of approval of the subdivision; (2) it serves two off-subdivision
    needs and provides no benefit to the subdivision itself; and (3) the drainage
    system does not follow any “natural” drainage path but instead collects and
    conveys water that would never enter the subdivision if not for the system.
    This evidence, they contend, raises a triable issue whether the drainage
    system is a public use under inverse condemnation standards.
    As to the County and the District jointly, Owners claim there is a
    triable issue whether defendants “have incorporated Murderer’s Creek into
    the public drainage system through their joint management, and evident
    mismanagement, of Drainage Area 46.” Owners also claim that even if
    18
    defendants’ “joint management of and control over the Murderer’s Creek
    watershed did not incorporate the Creek into the public drainage system,”
    they are liable “if their management of Drainage Area 46 places a
    disproportionate and therefore ‘unreasonable’ burden on downstream
    riparian property owners.” They contend the trial court erred by failing to
    apply the six “Locklin factors” required to analyze this issue.
    IV.
    Plaintiffs’ Claims Fail As a Matter of Law.
    Whether an improvement or waterway is a public use or public work
    for purposes of inverse condemnation liability is a question of law when
    factual issues are not in dispute. (See Locklin, 
    supra,
     7 Cal.4th at pp. 369-
    370.)
    A. Plaintiffs Have Not Raised a Triable Issue Whether the
    Spillway Is a Public Improvement or Use and Given the
    Undisputed Facts It Is Not a Public Work As a Matter of Law.
    Locklin established that “a governmental entity may be liable under
    the principles of inverse condemnation for downstream damage caused by an
    increased volume or velocity of surface waters discharged into a natural
    watercourse from public works or improvements on publicly owned land” “if it
    fails to use reasonably available, less injurious alternatives, or if it has
    incorporated the watercourse into a public drainage system or otherwise
    converted the watercourse itself into a public work.” (Locklin, 
    supra,
    7 Cal.4th at pp. 337-338, italics added.) Owners contend there is a triable
    issue of fact as to whether the MS 102-72 spillway—the failure of which they
    assert caused turbulence that damaged their land—was a public
    improvement.
    The three facts Owners contend support a finding of public
    improvement or use are, as we have said, that the County required the
    19
    developer to construct a drainage system and place it within an easement
    dedicated to the County; that the spillway served the needs of two areas
    outside of MS 102-72 while “providing essentially no benefit to the residents
    of [MS 102-72]”; and that the drainage system collects water from outside its
    “natural” drainage path and directs it to the discharge point at the Creek.
    1. Requiring Construction of the Drainage System and an
    Offer of Dedication Did Not Convert Private Improvements
    into Public Works.
    There is no genuine dispute about the material facts concerning the
    spillway or the other drainage improvements. The County imposed on the
    developer a condition requiring it to “construct, install and complete . . . tract
    drainage,” and a County ordinance required it to collect and convey “[a]ll
    surface waters flowing from the subdivision in any form or manner” from the
    development to the nearest natural watercourse with a definable bed and
    banks or to a public storm drainage facility. It required the developer to offer
    to dedicate easements for drainage purposes to the County.
    The developer of MS 102-72—not the County—designed and built
    improvements to satisfy these requirements, including underground drainage
    pipelines, catch basins, and an outfall at the Creek with a “spillway feature
    (‘Spillway’) comprised of grouted and loose rock riprap lining the earthen
    banks of the Creek.” The waters flowing through the pipelines consisted of
    runoff from MS 102-72, including a private road serving that subdivision
    known as “Kelly Ann Court”; runoff from an adjacent subdivision referred to
    as “Sub. 4234”; and runoff from Gloria Terrace, a county road adjacent to the
    subdivision. The purpose of the spillway was to protect the bed and bank of
    Murderer’s Creek against erosion from the waters spilling into the creek from
    the pipeline.
    20
    The County required the subdivider to offer easements to the County
    for drainage purposes, and the subdivider did so. The County has thus far
    never expressly accepted the offer. There are no records of the County ever
    having maintained or repaired the pipeline, outlet or spillway. The County
    has never performed maintenance or repairs to the portion of Murderer’s
    Creek upstream of plaintiffs’ properties or installed any improvements in the
    creek bed or channel.
    The facts Owners claim indicate the spillway is a public work are
    essentially undisputed.5 And for the following reasons, we conclude as a
    matter of law that they do not show the County converted the Spillway into a
    public drainage system.
    Owners’ argument is somewhat difficult to follow. It begins with the
    proposition that “ ‘construction and maintenance of storm drainage systems
    are matters of “public policy,” and such a system created by a public entity
    becomes a “public improvement” and a “public use.” ’ ” Citing pre-Locklin
    5  Owners assert, without citation, that the drainage improvements
    required as conditions for their subdivision “provid[e] essentially no benefit to
    the residents of the Subdivision.” (Italics added.) There is no evidence to
    support this assertion, and the County’s evidence shows the opposite is true.
    For example, a catch basin and the pipeline buried under the MS 102-72
    collected and carried runoff from that subdivision, including the private cul
    de sac that serves it, to the outfall and into the creek. The spillway beneath
    the outfall was designed to prevent erosion of the creek bed and banks
    adjacent to it, which were part of the subdivision.
    Owners also assert, again without citation, that the drainage “system”
    that the County required the subdividers to construct convey waters that
    would “never enter the Subdivision . . . were it not for the drainage system.”
    We have reviewed the evidence proffered by Owners and find no support for
    this assertion. Further, we note it is undisputed that the road and
    subdivision that Owners describe as the “off-subdivision” areas served by
    these improvements, Gloria Terrace and Subdivision 4234, are immediately
    adjacent to MS 102-72.
    21
    cases for that proposition, it proceeds to contend that “[i]t does not matter
    whether the public entity constructed the drainage improvements itself or
    whether, as is more common (and happened here), the public entity required
    a private property owner to construct [them] through its ‘approval of the
    subdivision maps and plans which include the drainage systems.’ ” The 1963
    decision it quotes for that proposition, Frustuck v. City of Fairfax,
    
    212 Cal.App.2d 345
     (Frustuck), has since been rejected by this court in
    Ullery, rejecting the proposition in Frustuck for which plaintiffs cite it here.
    Division Three of this court stated, “Appellants misconstrue the law when
    they state that the subdivision map approval process represents a sufficient
    level of governmental involvement to constitute a public use or improvement
    subjecting the public entity to inverse condemnation liability. The cases do
    not stand for the proposition that approval alone creates liability in inverse
    condemnation.” (Ullery, supra, 202 Cal.App.3d at p. 571.)
    Further, Frustuck was implicitly overruled by Locklin. In Locklin, the
    plaintiffs alleged that the city and county had allowed development of
    properties upstream of plaintiffs’ properties, required developers to construct
    roads, rights of way, culverts, storm drains and other public improvements in
    the watershed and required irrevocable offers of dedication of storm drainage
    easements on creekside properties as a condition of development permits.
    (Locklin, 
    supra,
     7 Cal.4th at pp. 340-342 & fn. 10.) Locklin held neither this,
    nor evidence that the city assisted residents in removing falling trees from
    the creek bed with permission from the owners and repaired an outfall above
    the creek, was sufficient to establish that the creek had been converted into a
    public work or improvement or a part of the public storm drainage system. A
    government entity, it opined, “must exert control over and assume
    responsibility for maintenance of the watercourse if it is to be liable for
    22
    damage caused by the streamflow on a theory that the watercourse has
    become a public work.” (Id. at p. 370, italics added.) Without a showing that
    the city or other defendants exercised control over the creek, it “remain[ed] a
    privately owned natural watercourse.” (Id. at pp. 370-371.)
    The Locklin court was not moved by the assertion that the city had
    required drainage easements. Noting that the evidence did not establish an
    express or implied acceptance of the drainage easements, the court expressed
    doubt that “requiring and/or accepting drainage easements across private
    property to a privately owned natural watercourse” is even “evidence of
    control over the watercourse itself.” (Locklin, 
    supra,
     7 Cal.4th at p. 370,
    fn. 21, italics added.)
    Notably, Owners cite no current authority for the proposition that a
    county’s imposition of conditions of approval through the Subdivision Map
    Act, including requirements that drainage improvements be implemented
    and that an offer to dedicate easements be made converts the improvements
    or the watercourse they affect into a public work, and we are aware of none.
    And Locklin repudiated the notion when, in rejecting an argument that the
    evidence in that case converted a creek into a public work, it opined,
    “Utilizing an existing natural watercourse for drainage of surface water
    runoff and requiring other riparian owners to continue to do so does not
    transform the watercourse into a public storm drainage system.” (Locklin,
    
    supra,
     7 Cal.4th at p. 370.) The latter is precisely what the County did in
    this case when it adopted an ordinance requiring upstream property owners
    of the Creek in the watershed to convey surface waters to and discharge them
    into the Creek. In doing so, it exercised its authority under the Subdivision
    Map Act to regulate the “design and improvement” of subdivisions by
    requiring subdivision developers to construct drainage improvements. (See
    23
    §§ 66411, 66418, 66419, 66421; 7 Miller & Starr, Cal. Real Estate (4th ed.
    2022) §§ 20:1, 20:25.)
    Requiring drainage-related improvements as conditions of approval of a
    map and offers to dedicate of easements is not an exercise of control over, or
    an assumption of responsibility for, maintenance of the improvement or the
    watercourse—especially where, as here (and in Locklin), there has been no
    acceptance of the dedication. (See Locklin, 
    supra,
     7 Cal.4th at p. 370 & fn. 21
    [questioning whether even accepted offer of dedication would suffice].) The
    County also argues persuasively that Ruiz v. County of San Diego (2020)
    
    47 Cal.App.5th 504
     (Ruiz) and the cases it relies on (Locklin, 
    supra,
     
    7 Cal.4th 327
    , DiMartino v. City of Orinda (2000) 
    80 Cal.App.4th 329
     (DiMartino) and
    Ullery, supra, 
    202 Cal.App.3d 562
    ), likewise refute the notion that
    improvements constructed in connection with a subdivision over which
    easements are offered but not accepted by the public entity, nonetheless
    become public works when they are used for drainage of public or other
    private properties. (See Ruiz, at pp. 509, 515-519; Ullery, at p. 570 [although
    creek was part of system draining 40-acre watershed, absence of dominion
    and control by public entities supported finding of no public use].) This is so
    even where the public has used the improvements for drainage for decades
    (see Ruiz, at pp. 514, 516 [50 or “ ‘over 60’ ” years].)
    Owners attempt to distinguish Locklin, claiming in that case the city
    had required developers “to place drainage easements over natural drainage
    swales across private property,” whereas here the County sought “to allow
    future County access to the drainage improvements (curbs, gutters, two drop
    inlets and catch basins, two underground drainage pipelines, and the
    MS 102-72 Spillway that ultimately failed) that the County had required [the
    developer] to install to serve two off-subdivision drainage needs. These
    24
    drainage improvements collect and convey surface water from two off-
    Subdivision locations onto and across the Subdivision, into an area that this
    water could never reach without them.”
    While Owners’ argument is not entirely clear, we take it to mean that
    by requiring offers to dedicate easements with respect to drainage
    improvements that served an adjacent subdivision and an adjacent street
    owned by the County (Gloria Terrace) and by diverting surface water to catch
    basins and pipelines to convey it to the Creek, the County in effect converted
    the improvements into public works. They cite no authority for this
    proposition, and we do not agree with it.
    Locklin held that using an existing natural watercourse for drainage of
    surface water runoff and requiring other riparian owners to do so “does not
    transform the watercourse into a public storm drainage system.” (Locklin,
    supra, 7 Cal.4th at p. 370.) We hold that requiring and using drainage
    improvements within a subdivision to convey water, including from an
    adjacent public road and adjacent subdivision, does not convert the
    improvements into public works either. As the County puts it, “Drainage
    improvements in all developments are designed to accommodate the
    anticipated storm water runoff quantities to be received by the
    development—including any runoff flows emanating from beyond a
    subdivision’s boundary.” Further, because developments “disrupt the natural
    drainage patterns,” “installation of artificial drainage facilities that collect
    and convey the runoff” that before “may have been conveyed as natural sheet
    flows” is necessary “to ensure the waters will safely pass through the
    community without causing damage.”
    25
    2. That the Drainage Improvements Serve Some Off-
    Subdivision Needs Does Not Convert Them into Public
    Works.
    Contrary to Owners’ arguments, requiring artificial drainage facilities
    and conveying water across properties over which it might not have flowed
    when the area was undeveloped does not convert those improvements into
    public works. Development requires that drainage systems be constructed to
    channel water beneath or around the obstacles development creates. A
    government could not require owners whose properties are not adjacent to a
    natural watercourse (i.e., landlocked) to drain waters from their properties
    into such a watercourse without allowing them to flow through properties
    that are closer to and/or adjacent to the watercourse. Thus, waters from
    landlocked properties must at least sometimes be conveyed through drainage
    improvements on other properties to reach a natural watercourse. This is
    recognized by the County in its ordinance regarding conveyance of surface
    waters, which provides that when “surface waters must be collected or
    conveyed beyond the boundaries of the subdivision in order to discharge into
    a natural watercourse,” appropriate easements must be obtained from “all
    property owners between the boundaries of the subdivision and the point at
    which the surface waters will be discharged into a natural watercourse.”
    For these reasons, it is not surprising that the Subdivision Map Act
    contemplated that improvements would be used for the good of the
    subdivision and properties beyond it. Its aim was to require local
    governments to exercise control over “ ‘the design of subdivisions for the
    benefit of adjacent landowners’ ” as well as “ ‘prospective purchasers and the
    public in general’ ” (Gardner, 
    supra,
     29 Cal.4th at p. 997.) It defined
    “[i]mprovement” to include work “necessary for the general use of the lot
    owners in the subdivision and local neighborhood . . . needs.” (§ 66419,
    26
    subd. (a), italics added.) As a leading commentator has put it, “[t]he local
    authorities have a great deal of latitude to require a subdivider to make
    adequate arrangements for drainage and sewage disposal both within and
    outside of the subdivision.” (7 Miller & Starr, Cal. Real Estate, supra,
    § 20:30.)
    A rule that government-required improvements on one subdivision are
    public if they serve drainage needs of properties outside that subdivision or
    convey water that might not naturally have flowed through the servient
    subdivision would undermine the purposes of the Subdivision Map Act.
    Indeed, local governments would be reluctant to “ ‘facilitate orderly
    community development, coordinate planning with the community
    pattern . . . , and assure proper improvements are made’ ” (Gardner, supra,
    29 Cal.4th at pp. 997-998) if doing so would impose responsibility and the
    associated costs on them for maintaining and repairing all such
    improvements.
    Owners contend our decision in DiMartino, supra, 
    80 Cal.App.4th 329
    supports the rule they propose because it “distinguished the installation of
    drainage improvements by private property owners to achieve private
    objectives from County-mandated drainage improvements required by public
    entities to achieve public objectives.” Owners misconstrue what we decided
    in DiMartino. In concluding the drainage pipe installed under the plaintiffs’
    house was not a public work, this court focused on whether the city had
    played any role in constructing that pipe and concluded the evidence did not
    show that it had. (Id. at pp. 336-344.) We referred to the purpose for which
    the pipe was built simply as evidence that it had been installed by an earlier
    owner of the lot. We did not hold or suggest that improvements that serve
    27
    drainage needs that extend beyond the subdivision are necessarily public
    works. (Id. at p. 344.)
    On the contrary, as the County points out, in DiMartino we rejected the
    argument that “connection of a private pipe segment to an admittedly public
    pipe segment converts the former to a public improvement.” (DiMartino,
    supra, 80 Cal.App.4th at p. 343; see also Ruiz, supra, 47 Cal.App.5th at
    p. 518 [fact that pipe was part of system that was used to drain valley
    watercourse, even over an extended period, did not constitute implied
    acceptance of drainage easement].) We further observed that “such a rule
    would allow circumvention of the Subdivision Map Act: a developer would no
    longer need to comply with requirements of dedication and acceptance,
    connection of any pipe on private property to a public roadway cross-culvert
    would transform the private pipe to a public one. We have found no case
    recognizing such a doctrine.” (DiMartino, at p. 343.)
    Owners also contend there is a triable issue here because the County
    “both refused to either ‘accept or reject’ the drainage easements [it] required
    developers to place over the bed and banks of the Creek” and therefore may
    have effectively accepted them and converted the improvements and the
    Creek into public works. Owners disregard the well-established rule that an
    acceptance of an offer to dedicate must be unqualified and unequivocal. (See
    Mikels v. Rager (1991) 
    232 Cal.App.3d 334
    , 353-354 [valid acceptance of offer
    must be “absolute and unqualified”]; Flavio v. McKenzie (1963)
    
    218 Cal.App.2d 549
    , 551-552 [“ ‘To effect a dedication of land by a private
    owner to public use, it is essential that there be an unequivocal offer of
    dedication by the owner and an unequivocal acceptance of the offer by the
    public’ ”].) “ ‘A dedication without acceptance is, in law, merely an offer to
    dedicate, and such an offer does not impose any burdens nor confer any
    28
    rights, unless there is an acceptance.’ ” (Mikkelsen v. Hansen (2019)
    
    31 Cal.App.5th 170
    , 176.)
    With respect to the drainage improvements on MS 102-72, the County
    did not accept the offer for the purpose it was offered, i.e., to access the
    improvements. It accepted the offer only for the purpose of recording the
    deed. An acceptance “for recording only” is not the kind of unequivocal and
    unconditional acceptance required to create a valid dedication. As for
    Subdivision 4983, the County stated it “did not accept or reject on behalf of
    the public any of the streets, roads, avenues or easements shown [on the
    Final Map] as dedicated to public use.” This was not an unequivocal or
    absolute acceptance. Given that the offer was irrevocable, declining to accept
    or reject it left open to the County the option to accept it at some later time.
    It is undisputed that it never expressly did so.
    Although there can be implied acceptance of an offer of dedication, it is
    undisputed that the County made no effort to maintain or repair the
    Spillway, any other improvements or the Creek itself. “Absent an easement
    or accepted dedication, liability is imposed on a public entity only when the
    public entity has exercised dominion and control over the private property.”
    (Ruiz, supra, 47 Cal.App.5th at p. 523.) In other words, in the absence of an
    express acceptance, there must be evidence of implied acceptance of
    dedication through, for example, the public entity’s assumption of
    maintenance or repair of the property. (Ibid.) In Ruiz, the court held the fact
    that public water drained through a privately owned pipeline did not
    constitute an implied acceptance of an offer of dedication that the public
    entity had previously expressly rejected. (Id. at p. 517.) The court indicated
    a previous case answered the question of “how much more” was required to
    constitute an implied acceptance, noting that in the earlier case “the public
    29
    entity was substantially involved in installing the privately owned pipe. For
    example, a surveyor employed by the public entity instructed the property
    owner ‘ “exactly what pipe to lay and how to do it” ’ and “provided the trucks,
    dirt, and water to complete the installation.” (Id. at p. 518.) There is no
    similar evidence here, and the County has provided evidence showing that it
    never owned, constructed or repaired the drainage improvements.6
    3. There Was No Implied Acceptance of the Drainage
    Easements by the County.
    Owners further contend they have raised a triable issue of fact as to
    whether the County otherwise assumed control or maintenance of the
    spillway because (1) it required the developer to install the drainage
    improvements; (2) its acceptance of the easements for MS 102-72—for
    recording only—suggests it impliedly accepted the easement; (3) there is a
    letter from the developer’s engineer to the County purportedly confirming the
    County’s obligation to maintain the drainage system; and (4) the October 22,
    1975 subdivision agreement confirmed that the County would assume
    responsibility for the drainage improvements after one year.
    We begin with the first two points. As we have explained, under
    Locklin and other cases, requiring improvements and easements does not
    convert the improvements into public works. It is likewise insufficient to
    constitute implied acceptance. To hold otherwise would be an end run
    6 Owners also argue that in requiring the dedication of the drainage
    easements, the County’s “purpose” was “to ensure [it] would have access to
    the system in perpetuity to perform periodic maintenance,” citing the
    declaration of Flett, their civil engineering expert. Even if the Flett
    declaration had been competent evidence of the County’s purpose or intent
    (which we discuss further below), it would not matter. “ ‘[A] dedication, like a
    contract, consists of an offer and acceptance, . . . proof of which must be
    unequivocal.’ ” (Biagini v. Beckham (2008) 
    163 Cal.App.4th 1000
    , 1009.) A
    party’s unstated purpose or intent is not acceptance of an offer.
    30
    around those cases. As we have discussed, Ullery and Ruiz indicate the kinds
    of conduct necessary for implied acceptance, such as substantial involvement
    in construction of the improvement or performing “maintenance and repair
    work.” (Ullery, supra, 202 Cal.App.3d at p. 568; accord, Ruiz, supra,
    47 Cal.App.5th at p. 523 [“Absent an easement or accepted dedication,
    liability is imposed on a public entity only when the public entity has
    exercised dominion and control over the private property”].) The undisputed
    evidence shows the County did not construct the improvements and
    performed no maintenance or repair work on the improvements.
    Turning to the third item, the letter from the developer’s engineer, that
    letter is not competent evidence that the County agreed to maintain the
    spillway. In the letter, the engineer provided the County with a cost estimate
    of the improvements for MS 102-72 and stated, “The following also includes
    the drainage system which will lie within dedicated easements in said
    subdivision and which shall be maintained by the county upon acceptance.”
    (Italics added.) The County objected to the letter as lacking foundation and
    improper opinion. The trial court did not rule on the objection but concluded
    the letter was not evidence of an agreement by the County that the drainage
    improvements would become public and be maintained by the County. We
    agree. The engineer is not a party to the subdivision agreement with the
    County, and his letter does not refer to that or any other agreement between
    the developer and the County. The engineer’s assertion may simply reflect an
    assumption or prediction that the easements would be accepted by the
    County. It is not evidence that the County agreed to accept the offer of
    dedication.
    Finally, Owners argue that the County’s agreement to maintain the
    drainage improvements was “reaffirmed, albeit ambiguously, by the
    31
    October 22, 1975, subdivision agreement” between the County and the
    developer for MS 102-72. The agreement includes a provision that following
    the completion of work (including the drainage improvements) for MS 102-72,
    the developer agreed to maintain the work and repair any defects for a one-
    year period. Owners argue the implication was that the County would
    assume maintenance of the drainage system after the one-year period. The
    inference Owners suggest we draw is not a reasonable one. The provision for
    a one-year period guaranteeing the adequacy of the improvements, which is
    required by county ordinance, is essentially a warranty that the
    improvements will work and, that if they fail during the warranty period, the
    developer will repair any defect. The Subdivision Map Act contemplated local
    governments would take steps to ensure that subdividers performed the
    obligations they undertook, including to construct required improvements.
    (See §§ 66499 et seq.; 74 Ops. Cal. Atty. Gen. 89 (1991).) The duration of a
    warranty or guarantee has no tendency to show the local government agreed
    to accept long-term responsibility for the improvements the subdivider
    warranted.
    B. Plaintiffs Have Not Established a Triable Issue As to
    Whether the Creek Was Incorporated into the Public
    Drainage System.
    Owners separately contend a triable issue of fact exists as to whether
    the Creek has been incorporated into the public drainage system through the
    Government Entities’ management of Drainage Area 46. Specifically,
    Owners argue that through their management, defendants are (1) requiring
    property owners developing parcels within the watershed to drain increased
    surface water runoff into the Creek; (2) collecting drainage fees from property
    owners for this use; and (3) choosing not to require property owners to install
    mitigation measures to reduce downstream runoff.
    32
    Owners’ first point lacks merit, as “[u]tilizing an existing watercourse
    for drainage of surface water runoff and requiring other riparian owners to
    continue to do so does not transform the watercourse into a public storm
    drainage system.” (Locklin, supra, 7 Cal.4th at p. 370.) There must be some
    affirmative action by the public entity to assume ownership or responsibility
    of the watercourse. (Ibid.) Here, neither the County nor the District had any
    ownership interest in the Creek nor performed any maintenance on the
    Creek on or upstream of Owners’ properties. Owners’ reliance on Souza v.
    Silver Development Co., supra, 
    164 Cal.App.3d 165
     is unavailing. There, this
    court found there was sufficient evidence to support the trial court’s finding
    that a creek had been incorporated into the public drainage system because
    the city “required the developer to construct storm drains to carry surface
    water into the creek and accepted the dedication of those drains.” (Id. at
    p. 170, italics added.) The city also required and accepted an easement for
    drainage along the creek channel. (Ibid.) Such express acceptance is wholly
    absent here.
    Second, the evidence shows that the Government Entities do not
    provide any storm drainage services to Owners’ properties or any upstream
    properties within the watershed. The “drainage fees” Owners reference are
    fees that the District collected pursuant to the Drainage Fee Ordinance
    enacted in 1988. The fees are imposed on all new development in Drainage
    Area 46 based on a dollar amount of square foot of impervious surface area
    developed. Revenue generated from these fees was placed in a fund intended
    to cover a local match that was required to implement a flood protection
    project. The project was not implemented because it did not meet federal
    requirements, and the District is now working with the City of Pleasant Hill
    33
    to determine whether to create a new drainage plan that would include new,
    proposed drainage improvements.
    The District’s act in implementing and collecting drainage fees to fund
    a proposed project that was never built does not raise a triable issue as to
    whether the District or the County incorporated the Creek into a public
    drainage system. Finally, that the Government Entities allegedly could have
    but did not require upstream property owners to install mitigation measures
    to offset the downstream runoff is not an affirmative act that demonstrates
    public control or dominion over the Creek. (Locklin, supra, 7 Cal.4th at
    p. 370.)
    C. There Is No Triable Issue of Fact Under the Locklin
    Reasonableness Test Because that Test Does Not Apply
    Unless There Is a Public Improvement.
    Owners next argue that even if the Government Entities’ management
    of Drainage Area 46 did not incorporate the Creek into the public drainage
    system, there is still a triable issue of fact as to whether their management of
    Drainage Area 46 was unreasonable to support liability under the
    “reasonableness” test set forth in Locklin, supra, 
    7 Cal.4th 327
    . Owners
    concede that the surface water entering the Creek does not drain from any
    publicly owned land but argues it does “emanate from improvements
    constructed on private parcels under the direct supervision of Respondents.”
    In Locklin, our Supreme Court explained that “[b]ecause a public
    agency, like any riparian property owner, engages in a privileged activity
    when it drains surface water into a natural watercourse or makes alterations
    to the watercourse, article I, section 19, of the California Constitution
    mandates compensation only if the agency exceeds the privilege by acting
    unreasonably with regard to other riparian owners.” (Locklin, supra,
    7 Cal.4th at p. 367.) To determine reasonableness, the court set out the
    34
    following six factors: “(1) The overall public purpose being served by the
    improvement project; (2) the degree to which the plaintiff’s loss is offset by
    reciprocal benefits; (3) the availability to the public entity of feasible
    alternatives with lower risks; (4) the severity of the plaintiff’s damage in
    relation to risk-bearing capabilities; (5) the extent to which damage of the
    kind the plaintiff sustained is generally considered as a normal risk of land
    ownership; and (6) the degree to which similar damage is distributed at large
    over other beneficiaries of the project or is peculiar only to the plaintiff.” (Id.
    at pp. 368-369.)
    “However, in determining whether [a public entity] acted unreasonably
    in this context, ‘the critical inquiry’ is not whether the public entity acted
    reasonably with respect to someone else’s property, but whether ‘the [public
    entity] acted reasonably in its maintenance and control over those portions of
    the drainage system it does own.’ ” (Ruiz, supra, 47 Cal.App.5th at pp. 526-
    527, italics added.) Similarly, as Division Three of this court has held,
    “Where a public improvement is unreasonably a substantial cause of the
    plaintiff’s damage, a public agency may be liable for its role in diverting
    surface water in order to protect urban areas from flooding.” (Skoumbas v.
    City of Orinda (2008) 
    165 Cal.App.4th 783
    , 796, italics added.) Thus, only
    where the public entity owns the property that has caused the harm or by
    conduct converts that formerly private property into a public work is the
    reasonableness of the public entity’s and the private owner’s conduct
    assessed. Because we have held as a matter of law that neither the drainage
    improvements nor the Creek was or became a public work, the
    “reasonableness” test set forth in Locklin is not implicated. There is
    therefore no triable issue of fact raised by this argument.
    35
    V.
    The Exclusion of Flett’s Custom and Practice Opinion About
    Homeowners’ Associations Was Harmless Because It Did Not Raise a
    Triable Issue Whether an Agreement Was Formed.
    Owners contend the trial court abused its discretion in sustaining the
    objection to a paragraph in their expert Flett’s declaration, without
    explanation. As we have recognized elsewhere, there is a debate as to
    whether the abuse of discretion standard of review that generally applies to
    evidentiary rulings should be applied in the context of summary judgment,
    where review is generally de novo. (Turley v. Familian Corp. (2017)
    
    18 Cal.App.5th 969
    , 978.) Owners do not argue we should review the trial
    court’s evidentiary ruling de novo here, “ ‘except to the extent the ruling is
    based on the court’s conclusion of law.’ ” We need not decide what standard
    of review applies to evidentiary rulings made in the summary judgment
    context because any error in excluding the opinion in Flett’s declaration was
    harmless.
    The trial court excluded Flett’s opinion that if the County had intended
    for the drainage improvements in MS 102-72 to be private, it would have
    included in the conditions for approval of the subdivision map a requirement
    that the property owner assume responsibility for maintaining the drainage
    system rather than requiring an irrevocable offer to dedicate the drainage
    easements to the County. Flett stated this was the custom and practice of
    the County and its failure to include a requirement that the owner form a
    homeowners’ association to take responsibility for the drainage
    improvements shows the County intended to take responsibility for them.
    Owners reprise this argument on appeal, arguing, “the absence of a County
    requirement that [the subdivision developer] establish a homeowners’
    36
    association for the MS 102-72 subdivision to provide for the maintenance of
    the drainage system is evidence that the County agreed to maintain it.”
    The Flett opinion, even if admitted, would fail to raise a triable issue
    because it exceeds the permissible use of custom and practice evidence.
    Generally, offers of dedication are governed by contract principles. (Mikels v.
    Rager, supra, 232 Cal.App.3d at pp. 353-354 & fn. 3.) Such offers must be
    accepted before they create binding obligations, and a “qualified acceptance of
    the offer of dedication [does] not result in a completed dedication of a public
    easement.” (Id. at p. 353; Biagini v. Beckham, supra, 163 Cal.App.4th at
    p. 1009; Copeland v. City of Oakland (1993) 
    19 Cal.App.4th 717
    , 722
    [conditional nature of public entity’s acceptance prevents creation of public
    liability for street].)
    Under general contract interpretation principles, “[i]t is a well-
    established rule that evidence of usage and custom may be introduced as an
    instrument of interpretation, but may not be used to create a contract.”
    (Magna Development Co. v. Reed (1964) 
    228 Cal.App.2d 230
    , 240, italics
    added; Weddington Productions, Inc. v. Flick (1998) 
    60 Cal.App.4th 793
    , 817.)
    Equally well-established is the rule that terms of a contract may be implied
    from custom and usage evidence only “ ‘in the absence of agreement to the
    contrary.’ ” (Binder v. Aetna Life Ins. Co. (1999) 
    75 Cal.App.4th 832
    , 851,
    italics added; Miller v. Germain Seed & Plant Co. (1924) 
    193 Cal. 62
    , 77; see
    Civ. Code, § 1655; 1 Witkin, Summary of Cal. Law (11th ed. 2017) Contracts,
    § 778, pp. 836-837.)
    Applying these principles, custom and usage evidence cannot be used to
    establish an acceptance of the offers to dedicate easements or the formation
    of any other agreement to maintain the improvements on the dedicated
    property. For that reason alone, Flett’s opinion about the “intent” of the
    37
    County, which he infers from the absence of a homeowners’ association
    requirement, does not create a triable issue as to whether the County
    accepted the offers and thereby undertook to maintain the drainage
    improvements.
    There is another reason the Flett opinion does not raise a triable issue
    regarding the MS 102-72 subdivision, which is that the term he would imply
    conflicts with the express terms of the parties’ agreement. As we have
    discussed, in the offer to dedicate, the subdivision developer provided, “It is
    understood and agreed that CONTRA COSTA COUNTY and its successor or
    assign shall incur no liability with respect to such offer of dedication, and
    shall not assume any responsibility for the offered parcel of land or any
    improvements thereon or therein, until such offer has been accepted by
    appropriate action of the Board of Supervisors, or of the local governing body
    of its successor or assign.” (Italics added.) The parties thus agreed that the
    County would not become responsible for the improvements unless its Board
    of Supervisors took appropriate action to accept the offer of dedication. A
    term requiring the County to bear that responsibility without any acceptance
    by the Board is contrary to the parties’ express agreement and therefore
    cannot be implied based on custom and practice evidence.
    In short, Flett’s opinion about custom and usage fails to raise a triable
    issue because it cannot be used for the purposes for which it was offered:
    either to imply an acceptance by the County of the offers of dedication and
    associated responsibility for the drainage improvements or to imply a term
    imposing such responsibility by means other than those specified in the
    actual agreement. For these reasons, any error in excluding that opinion is
    harmless.
    38
    VI.
    Plaintiffs Concede Their Tort Claims Fail If the Inverse
    Condemnation Claim Is Not Viable.
    Lastly, Owners concede their related tort causes of action for nuisance,
    trespass, and dangerous condition on public property are all conditioned on
    the viability of their inverse condemnation claim. For example, Owners
    argue that they have a claim for nuisance if it is proven that either the
    drainage improvements or the Creek is part of the public drainage system.
    Because we conclude they are not, Owners’ tort claims also fail.
    DISPOSITION
    The judgment is affirmed. Defendants shall recover their costs on
    appeal.
    39
    STEWART, P.J.
    We concur.
    RICHMAN, J.
    MILLER, J.
    Shenson v. County of Contra Costa (A164045)
    40
    Trial Court:Contra Costa County Superior Court
    Trial Judge:     Hon. Jill C. Fannin
    Counsel:
    Seiler Epstein, MacKenzie & Albritton, Mark L. Mosley, for Plaintiffs and
    Appellants.
    Bold, Polisner, Maddow, Nelson & Judson, Timothy J. Ryan, for Defendant
    and Respondent.
    41
    

Document Info

Docket Number: A164045

Filed Date: 3/30/2023

Precedential Status: Precedential

Modified Date: 3/30/2023