Opinion
GRODIN, J.
In this administrative mandamus proceeding (Code Civ. Proc., § 1094.5) we review a judgment granting a peremptory writ of mandate.1 The writ commands the California Coastal Commission (Commission) and the South Central Coast Regional Commission (Regional Commission)2 to confirm a vested right in the Halaco Engineering Company [57]*57(Halaco) to continue the use of a settling pond and waste disposal site on its property which is adjacent to the sand dunes of Ormand Beach in Ventura County, without obtaining a permit to do so from the Regional Commission. The property is located within the City of Oxnard and the coastal zone.3
The Commission and the Regional Commission appeal,4 contending that the trial court erred both in utilizing its independent judgment in reviewing the Regional Commission’s decision that Halaco did not have a vested right to continue its operations, and in finding that Halaco did have that right. Halaco argues that its claim to a vested right to continue its operations is one arising under the Fifth and Fourteenth Amendments to the United States Constitution and article I, section 19, of the California Constitution. On that basis it asserts an exemption from the controls placed on coastal zone development by the Coastal Act, and argues that the trial court properly exercised its independent judgment on the administrative record in upholding its claim. Halaco also appeals from the affirmance of the decision that a propane gas tank it has placed on its property is a “development” within the meaning of and subject to the permit requirement of the Coastal Act, and from the denial of attorney fees.
We shall conclude that application by the trial court of the independent judgment standard of review is proper when a developer seeks review of a Commission decision denying a vested rights claim. We shall also conclude that substantial evidence supported the trial court’s determination that the decision of the Regional Commission was not supported by substantial evidence, and that the weight of the evidence supported Halaco’s claim of vested right to the continued use of its settling pond and waste disposal site. Finally, we also affirm the trial court’s judgment holding that placement [58]*58of the propane tank on its property is a development for which a permit is required.
I.
Halaco operates a nonferrous scrap metal recycling plant for which it obtains scrap, principally aluminum and magnesium, from other users and smelters. It converts the scrap into ingots of metal alloys. Because the scrap is often contaminated with dirt and other impurities when received by Halaco, it must be washed prior to smelting. The water and fluxing salts, and the impurities removed in the water washer, are pumped into a settling pond where evaporation of the water leaves a powdery residue of particulates. The settling pond is contained within a berm whose trapezoidal walls were created with dirt taken from the bottom of the pond and later enlarged by depositing on them the material dredged periodically from the pond.
The Halaco plant itself consists of several foundry buildings and other structures located on a 12-acre parcel of land in southwest Oxnard to the immediate west of the Oxnard Industrial Drain. This drain, which runs in a north-south direction, separates the factory from the 28-acre parcel on the eastern side of the drain on which the settling pond is located. The remainder of the eastern parcel is used for disposal of the material dredged from the pond. The pond which occupies approximately 15 acres of this parcel is bounded on 3 sides by the drain and Halaco’s property line. With the completion of the berm surrounding the pond, Halaco commenced use of the remaining 13 acres for the deposit of the dredged material, doing so by extending the northern berm toward the northern boundary of the property.
The Halaco plant was constructed on the eastern parcel over the period between 1965 and 1973. Actual operation of the plant and use of the settling pond began in 1970. The pond and waste disposal area have been used for these purposes continuously since 1970. Prior to construction of its Oxnard facility Halaco had operated a smelting plant in Gardena, California. It moved its operations to Oxnard for several reasons, all of which were directly related to the coastal site where temperatures would be lowered naturally, there was no danger of polluting potable water, and disposal of the waste in the manner described would be lawful. The elevation of the plant is higher than that of the eastern parcel because the plant is on the site of the former Oxnard city dump. There had been unpermitted dumping on the eastern parcel. When Halaco obtained its building permits for construction [59]*59of the buildings on the western parcel, the site was zoned M-2, in which heavy industrial uses were permitted.
Halaco did not apply for a permit to continue its use of the settling pond and waste disposal area, or any of its operations, following the adoption in 1972 of the California Coastal Zone Conservation Act (former § 27000 et seq.) the predecessor to the present Coastal Act. It believed that no permit was necessary since it had been operating its facility prior to the effective date of the act. When this court held in South Coast Regional Com. v. Gordon (1977) 18 Cal.3d 832 [135 Cal.Rptr. 781, 558 P.2d 867], that a vested right claim may not be asserted in defense to an action by a regional commission unless the defendant has previously submitted a vested rights claim to the commission, Halaco submitted an application for approval of a claim of vested rights to the Regional Commission pursuant to title 14, California Administrative Code section 13201 on July 26, 1978. No action by the Regional Commission, the City of Oxnard, or any other agency had been taken at that time to subject Halaco to the permit requirements of the Coastal Act. In its application Halaco claimed a vested right and exemption from the permit requirements of the Coastal Act for its entire operation.
The principal and dispositive factual question regarding the eastern parcel, as seen by both Halaco and the Regional Commission, was whether Halaco had all permits required by the City of Oxnard for the construction and use of the settling pond including the deposit of solid material dredged from the pond on the remainder of the waste disposal site in the manner in which these operations were being conducted when the permit application was made. Halaco contended, and presented uncontradicted evidence, that the structures on the western parcel had been built pursuant to permits properly issued by the City of Oxnard, that the city was aware of the contemplated use of the eastern parcel for a settling pond and waste disposal site, and that the city with knowledge of the full scope of the intended use of the pond and disposal site had advised Halaco that no further permits were required for the construction of the settling pond. Halaco had obtained special use permits for its operation of the foundry and smelters, but did not have a grading permit for construction of the settling pond or removal of the settled deposits.
The Regional Commission considered the various components of Halaco’s operations separately. The settling pond and waste disposal site were considered apart from the structures comprising the plant on the western parcel, as was the 18,000-gallon propane tank that Halaco had placed on the western parcel without a permit from the Regional Commission after the Coastal Act had gone into effect. After a hearing on September 28, 1979, the [60]*60Regional Commission voted to uphold the vested right claims as to all of the components of the application except the use of the settling pond and waste disposal site, and the propane tank. In voting to reject the claimed right to use the settling pond in the manner for which it had been constructed, the Regional Commission also voted to reject the claimed right to deposit the material dredged from the pond on the remainder of the eastern parcel.
The Regional Commission denied Halaco’s claim of vested rights with respect to the eastern parcel for deposit of material outside the settling pond, expansion of the settling pond either by raising the width of the banks (berms) by outward expansion or by increasing their height, or by any activity that would cause the pond to exceed the dimensions shown on a 1969 blueprint not-to-scale sketch which Halaco had supplied to the City of Oxnard in that year when it inquired, prior to creating the settling pond, whether any additional permits would be necessary. The Regional Commission reasoned that “as a vested right cannot exist for that which is not specifically defined, there can be no finding of vested right beyond those plans (1969).” Halaco appealed to the Commission which declined to hear the matter, ruling that it did not raise a “substantial issue.”5
Contending that the finding of the Regional Commission was without evidentiary support, and was contrary to the uncontradicted evidence, Halaco petitioned for writ of mandate (Code Civ. Proc., § 1094.5) and urged the trial court to apply the independent judgment standard of review mandated by this court in Bixby v. Pierno (1971) 4 Cal.3d 130 [93 Cal.Rptr. 234, 481 P.2d 242]. It also contended that its propane tank was not subject to the jurisdiction of the Regional Commission because moving it onto the property did not involve the placement of solid material in the coastal zone.
After consideration of the administrative record the trial court found that Halaco had been operating its plant at all times since 1970, that the plant included the settling pond and waste disposal site “through the operation of which it disposes of its solid waste. The solid waste suspended in water is pumped into the pond, settles to the bottom of the pond, and is dredged out and is principally deposited on the northern berm of the pond expanding that berm onto Halaco’s waste disposal site north of the pond.”
In its conclusions of law6 the court held that “since the instant action involves a claim of vested rights, the Court must exercise its independent [61]*61judgment in determining whether or not findings are supported by the weight of the evidence.” It then found that the preponderance of the evidence established that Halaco had intended to use the settling pond and waste disposal site in the manner in which it had been used continuously since 1970; that the use was fully explained, understood, and considered by the city in the city’s determination that no permits for that use were required; that there was no evidence to support a determination that this decision was based solely on the 1969 sketch or that the city had determined only that no permit was needed for the construction of the pond in the dimensions shown in the sketch as contrasted with the actual use of the pond.
The trial court also ruled that the administrative record failed to reflect that proposed revised findings on which the Regional Commission sought to uphold its decision had been adopted by the Regional Commission or served on and delivered to Halaco, and that the proposed findings related to the settling pond were both contrary to the determination made by the Regional Commission after the September 28, 1979, hearing and unsupported by the evidence. Accordingly, they were arbitrary and capricious.
The court also held that the settling pond had been constructed in good faith and in conformance with the law and so used since 1970 in conjunction with the waste disposal site. The use had been consistent with the claim of vested rights which had not been waived. The court held that in determining that Halaco had a vested right to its settling pond and waste disposal site at all, the Regional Commission had necessarily rejected arguments that: (1) Halaco had been required to but had not obtained a* grading permit, special use permit, and variance; (2) a permit was a prerequisite to obtaining a vested right to use the pond and disposal site in the manner in which it had been used; and (3) Halaco’s rights depended upon an estoppel. Reasoning that because the Regional Commission had not adopted any of those grounds, and had not made a finding that an estoppel existed as to the City of Oxnard but did not extend to the Regional Commission, the trial court concluded that it could not consider any of those grounds as support for the Regional Commission’s decision because its review was limited to the grounds actually invoked by the Regional Commission for its decision.
Finally, the court held that Halaco had demonstrated by a preponderance of the evidence that the Regional Commission should have, and did, grant its application for approval of the claim of vested rights to continue its use of the settling pond and waste disposal site, but the evidence showed and as a matter of law the propane tank constituted the placement or erection of solid material in the coastal zone and was subject to the permit requirement of the Coastal Act.
[62]*62These appeals followed.
II.
At the time these administrative proceedings commenced, section 30601 required that a coastal development permit be obtained from a regional commission for any development in the area in which the Halaco plant is located.7 “Development” as defined by section 30106 included “the placement or erection of any solid material or structure; . . . disposal of any dredged material . . .; [and] grading . . .” on the property. Section 30608 exempted from the permit requirement any development for which a “vested right” had been acquired: “No person who has obtained a vested right in a development prior to the effective date of this division or who has obtained a permit from the California Coastal Zone Conservation Commission pursuant to the California Coastal Zone Conservation Act of 1972 (commencing with section 27000) shall be required to secure approval for the development pursuant to this division; provided, however, that no substantial change may be made in any such development without prior approval having been obtained under this division.” If a development was not exempt under that section, a permit issued pursuant to section 30601 was “subject to reasonable terms and conditions in order to ensure that such development or action [would] be in accordance with the provisions of” the Coastal Act. (§ 30607.)
Because the Coastal Act had been preceded by the Coastal Zone Conservation Act, an initiative measure adopted in 1972, which also required coastal zone development permits for any development for which a vested right had not been acquired when that act became effective (former §§ 27401 & 27404), a developer such as Halaco which had not obtained a permit under the 1972 act could claim a vested right only if that right had been perfected under the exemption provisions of the 1972 act. The development would not otherwise be “lawful,” and thus the developer could not claim a vested right to continue.
[63]*63Construing together former sections 274008 and 274049 in San Diego Coast Regional Com. v. See The Sea, Limited (1973) 9 Cal.3d 888 [109 Cal.Rptr. 377, 513 P.2d 129], we concluded that persons who had performed substantial lawful construction of their projects prior to February 1, 1973, were exempt from the permit requirements of the 1972 act. (9 Cal.3d at p. 890. See also, Avco Community Developers, Inc. v. South Coast Regional Com. (1976) 17 Cal.3d 785, 799 [132 Cal.Rptr. 386, 553 P.2d 546].)
A developer who claims exemption from the permit requirement of the act on grounds that he has a vested right to continue his development is required to seek confirmation of his vested right claim by a regional commission and may not first assert the claim in defense to an action by the regional commission to enjoin further development. (South Coast Regional Com. v. Gordon, supra, 18 Cal.3d 832; State of California v. Superior Court (1974) 12 Cal.3d 237 [115 Cal.Rptr. 497, 524 P.2d 1281] (hereinafter Veta).) As we explained in Gordon and Veta, the constitutional underpinnings of the vested right doctrine do not preclude delegation to the regional commission of the power to make the initial determination whether an exemption should be recognized as long as judicial review of that decision is afforded. We have not, however, examined the question presented here—the standard of judicial review to be applied by the trial court when review of a decision denying a vested right claim is sought.
In several decisions the Court of Appeal has concluded that the independent judgment standard of review required by Strumsky v. San Diego County Employees Retirement Assn. (1974) 11 Cal.3d 28, 34 [112 Cal.Rptr. 805, 520 P.2d 29], must be applied by a superior court reviewing the denial of a vested right claim. (See, e.g., Stanson v. San Diego Coast Regional Com. (1980) 101 Cal.App.3d 38 [161 Cal.Rptr. 392]; Transcentury Properties, Inc. v. State of California (1974) 41 Cal.App.3d 835 [116 Cal.Rptr. 487].) In each case the Court of Appeal has reached this conclusion through reasoning that the vested rights doctrine derives from the constitutional guarantee that property may not be taken without due process and just compensation, and that it therefore follows that the denial by the [64]*64Regional Commission of a claim of vested right made under the Coastal Act affects a fundamental property right.10
The Commission questions the premise underlying these decisions, noting that the denial of a vested rights claim does not directly affect the right of the developer to proceed with his project. The impact of the decision is to subject the developer to a further administrative proceeding—the permit process. The Commission concedes that if a developer has acquired a vested right under the Coastal Act to proceed without a Commission permit, the Commission has no authority to impose additional conditions on the development. It is argued, however, that determination of a claim of vested right involves only the question of whether the developer has satisfied the statutory criteria for recognition of a vested right. Resolution of that question adversely to the claimant affects a constitutionally rooted vested right only if due process either precludes imposing on the claimant the burden of the permit process or the imposition of any new conditions on the right of the claimant to proceed with the development of his property. In the view of the Commission, therefore, the question of whether an action of the Commission will have a substantial effect on a fundamental, vested, property right can only be determined once the Commission takes action on the permit application.
We agree with the Commission that denial of a vested right claim, in the context of the Coastal Act, does not directly affect a fundamental right of the claimant. The burden of compliance with the permit requirement is insubstantial, and the Commission might, after all, grant the permit or impose conditions which are not sufficiently onerous to constitute a taking or otherwise offend principles of due process. It does not follow, however, that the trial court erred in using its independent judgment on the evidence taken in the proceedings related to Halaco’s application for recognition of its claimed vested right. The statutory scheme under which vested rights claims and permit applications are considered by the Commission, and Commission decisions are reviewed by the court satisfies us that the Legislature contemplated (a) that any claim of vested rights would be finally [65]*65resolved before an application for a permit is required, and (b) that judicial review would be on the basis of an independent judgment standard.
Section 30801 authorizes review of Commission decisions only by petition filed within 60 days after the decision to be reviewed has become final. Halaco has followed this procedure. If, as the Commission contends, Halaco’s judicial challenge to the denial of its vested rights claim were to be tested on the basis of a substantial evidence standard, and on that basis denied, the matter would then go to the Commission for action on a permit application. If the Commission were to grant the permit without qualifications, or impose qualifications which Halaco did not challenge, that would be the end of the matter. But if the Commission were to deny the permit or impose conditions which Halaco challenged as unduly burdensome upon a vested right, Halaco would then be required to challenge the Commission decision on its permit application by a second petition in the superior court. Inasmuch as the vested rights claim would then be squarely presented, Halaco would be entitled to review by a court exercising its independent judgment on the evidence. (Bixby v. Pierno, supra, 4 Cal.3d 130, 141-143.) The Commission apparently assumes that such review would be available to Halaco at this stage.
It is highly unlikely that the Legislature intended a two-step procedure with different standards of review. Not only would this be cumbersome, but it would require departure from the procedures under which judicial review is undertaken pursuant to Code of Civil Procedure section 1094.5. Most significantly, the court which had determined that the decision of the Commission was supported by substantial evidence would be called upon, months or years later, to exercise its independent judgment on the basis of the same record in order to determine whether the Commission’s permit decision should be upheld. It is improbable that the Legislature contemplated that the Commission would go through a possibly futile permit application proceeding, or that the superior court would be required to entertain repetitive petitions asserting the vested rights claim in order to assure a claimant such as Halaco its right to review under the court’s independent judgment on the evidence.11
[66]*66We cannot attribute such an intent to the Legislature which incorporated the provisions of Code of Civil Procedure section 1094.5 into section 30801. The former provides that where the reviewing court “is authorized by law to exercise its independent judgment on the evidence, abuse of discretion is established if the court determines that the findings are not supported by the weight of the evidence; and in all other cases, abuse of discretion is established if the court determines that the findings are not supported by substantial evidence in the light of the whole record.” (Code Civ. Proc., § 1094.5, subd. (c).) The Legislature has thereby indicated an intent that there be a proceeding to review a Commission adjudicatory proceeding at which the independent judgment standard of review will be available. There is no suggestion in the Coastal Act that the Legislature contemplated repetitive proceedings to review the denial of a vested rights determination under different standards of judicial review.
Therefore, while accepting the Commission’s argument that a landowner or developer such as Halaco, which is operating an industrial plant may not claim a vested right to obtain a land use permit, or to be free of valid newly enacted land use regulations (see United States v. Riverside Bayview Homes (1985) 474 U.S. 121, — [88 L.Ed.2d 419, 426, 106 S.Ct. 455, 459]; American National Ins. Co. v. Fair Employment & Housing Com. (1982) 32 Cal.3d 603, 607 [186 Cal.Rptr. 345, 651 P.2d 1151]) we find that argument irrelevant in the context of this statutory scheme. Having provided a procedure whereby a developer may obtain a determination of a claim to a vested right to proceed with a development for which he has all required permits and in which he has invested substantial work and funds, and having provided that if a claim of vested right is confirmed the developer need not apply for a permit, the Legislature did not intend to postpone final judicial review of the vested rights claim until after application for a permit was made and acted upon.12
III.
Halaco’s vested right claim was received by the Regional Commission on July 26, 1978, and filed the following day. Halaco claimed exemption [67]*67from the permit requirements of the act for the operation of its business as a smelter of nonferrous metals, and described the “development” involved as an “integrated whole” for the conduct of that business. The process of smelting and producing of ingots was described as was the preparation of the scrap by removal of the dirt or “dross” from the metal: “As to the dross, prior to the smelting process, the dirt is separated from the scrap by a water washer. The dirt and the water used in the separation is pumped into the settling pond.” The dredging operation was also described: “Use of the settling pond was commenced by construction of the perimeter berms in 1970. Thereafter there has been periodic dredging of the fill material from the pond, which fill material is placed immediately adjacent to the existing berm.”
Submitted with the claim were copies of the permits under which structures had been built on the Halaco property. A letter to the Regional Commission from a planning associate in the Oxnard Planning Department listed special use permits granted to Halaco for its operation, including an August 1965 permit for a magnesium smeltering plant facility, a May 1969 extension of the permit to include a foundry-furnace building, and an April 1972 amendment of the permit to add a foundry building and welding shop. The letter noted that there had been no application for nor permit approved for the “retention basin.”
In support of its claim that its vested right extended not only to the operation of the foundry and smelters, but also to the entire integrated process of creating the ingots of metal alloys including the water washing process, use of the settling pond, and disposal of dredged material on the eastern parcel, Halaco submitted declarations from persons involved in the location and construction of the plant, and correspondence with and from city officials who had participated in the events leading to the 1970 commencement of operation. These documents included:
1. Declarations of Leslie Fine, who had been in 1965 and at the date of the hearing continued to be a director, vice president, and general manager of Halaco. Fine stated in substance that the undeveloped, contiguous waste disposal site had been one of the factors leading to the relocation of the Halaco operation to the Oxnard site, and Halaco had at all times intended to use the entire eastern parcel as a solid waste disposal site. This intent had been made clear to Oxnard officials at various times since the relocation planning commenced.
2. A copy of a June 24, 1965, letter from the Oxnard “coordinator” to a representative of the then owner of the Halaco site stating that the firm [68]*68would like to move from Gardena to the Oxnard area if a suitable site could be found. The letter describes the Halaco operation and the need for a waste disposal site.13
3. A July 1965 letter from Halaco to the coordinator reviewing conversations regarding Halaco’s acquisition of a site and construction of a plant in Oxnard, in which the disposal of solid waste on the berm, and widening of the berm were described.14 That letter also noted that if the agreement were reached Halaco would be granted a special use permit and business license to operate the proposed plant, that the area would not be rezoned, but would be kept for heavy industrial use.
4. Declarations by Steven Thurston, the Oxnard City Engineer from October 1959 through March 1977, the first stating that in 1969 the building department had referred to him an inquiry by Halaco which had then obtained special use permits for the construction of its magnesium smelting plant and foundry building. Halaco had inquired whether any additional permits were needed for its intended development of a settling pond or ponds. With the inquiry Halaco had enclosed a blueprint sketch, not drawn to scale, of the proposed settling pond(s).15 The building department, to which the inquiry had been directed, had determined that all necessary building permits had been obtained, and because that was the extent of its concern had referred the matter to the city engineer. Thurston then had several conversations with Fine, Halaco’s vice president and general manager, regarding the need for additional permits during which Thurston learned or already [69]*69knew that Halaco intended to dispose of effluent into the ponds. Thurston declared: “As part of my considering whether any additional permits were required by Halaco, I specifically considered whether Halaco needed a permit for those settling ponds. It was my opinion that the construction and use of those ponds by Halaco was comparable to Halaco grading its real property, and at that point in time, the City of Oxnard did not require any permit for grading. Accordingly, in my capacity as City Engineer I determined and informed Mr. Fine that Halaco did not need any additional permits for its then contemplated development.”
Thurston’s supplemental declaration stated that the building department was responsible for determining whether grading permits were needed for a proposed development such as that of Halaco, and that building department personnel had advised him that no permits for which that department was responsible were needed. He therefore did not reconsider whether a grading permit was necessary for the construction and operation of the settling ponds. “My determination concerned whether any other permits of any kind or nature were needed, considering, among other things, the purpose and nature of the settling ponds, the fact that they were to be constructed and operated in an M-2 heavy manufacturing zone, and that by their nature, their use over time would constantly change their dimensions and shape. While Halaco at that time intended to construct and operate three settling ponds, I generally considered the matter in terms of Halaco using a particular size area for settling pond purposes regardless of whether the particular area comprised one large settling pond or several small settling ponds.”
5. A copy of an April 25, 1972, letter from the Oxnard Planning Director to Halaco advising that additional information including “the description of the waste products of the process and how they are to be handled” was necessary because a newly granted special use permit for an additional foundry building had been appealed, and Halaco’s reply letter dated May 5, 1972. That reply again described the waste disposal process as including deposit on the eastern parcel.16
Other documents establish that a bridge over the drain was lawfully built in 1969 to connect the two parcels and facilitate the dredging and disposal operation.
[70]*70Halaco asserted that the permits under which it commenced operation in 1970 authorized not only the construction of its buildings and settling pond, but the operation of its business as an integrated process which included the use of the settling pond and disposition of material dredged therefrom on the northern berm and that the city was estopped to contend otherwise. This claim was supported by a September 21, 1979, letter from a deputy city attorney to counsel for the Regional Commission and Halaco. In that letter, also made part of the record of the administrative proceeding, the deputy city attorney stated that in 1969 the Oxnard codes did not make specific reference to settling ponds as permitted or prohibited in any zone, and that there had been none in use and no prior requests for construction of one. Halaco had actively and openly sought information from the city as to whether any permit was necessary for construction and use of the pond, and that Thurston was a responsible city employee with ostensible authority to make the statement that no permit was necessary. Based on this, and the construction, operation, and use of the pond for nine years without any assertion by the city that the use was improper or that any special use permit was necessary, the city attorney believed that it would be unfair and inequitable to require a special use permit, and that estoppel and laches would bar either that requirement or an action to enforce such a requirement. The city attorney declined to render an opinion as to what other permit or permits would have been legally required by the city in 1969 in light of the complex codes and lesser environmental concern at the time Halaco’s inquiry was made. He stated, however, that “the mere fact that the use of the settling pond was quite apparent to the City during this period and the City refused to ask that a special use permit be applied for indicates that the City felt one was not necessary at that time.”
No written administrative staff report was prepared for the September 28, 1979, hearing at which Halaco’s application was first considered. A staff member recommended orally that the claim of exemption be approved for all of the developments on the western parcel except the propane tank.17 Denial of the claim of exemption was recommended as to the propane tank, although it had local approval, because it had been installed after the permit requirement of the 1972 act became effective and in the opinion of the staff did constitute a development for which a permit was required.
The oral staff report noted with regard to the settling pond and waste disposal area that Halaco had submitted information that the pond was a [71]*71nonobnoxious manufacturing process which did not require a special use permit in the M-2 zone in which it was located; and that Halaco, based on the advice of the city engineer, had not been required to obtain a grading permit.
The staff nonetheless concluded that the pond was not a lawful use, reasoning that a local permit or variance had been required by Oxnard ordinances for the pond in 1969 because, although it was a use incidental to the smelting operation in the M-2 zone, the pond was on a separate parcel. The 1979 staff interpretation of the Oxnard ordinances in effect in 1969-1970 was that uses customarily incidental to an operation for which a special use permit is granted were covered by that permit, but this was true only if the use was on the same lot for which the permit had been granted. The staff acknowledged that the pond was a use incidental to the smelting operation.
The staff also interpreted the Oxnard ordinance to require a permit for the pond if it originally required a grading permit and was hazardous and/ or obnoxious. The staff then asserted that a grading permit had been necessary at the time the pond was created. This assertion was based on (1) Oxnard’s adoption prior to the time the pond was constructed of the Uniform Building Code which provided for grading permits for moving the amount of material that Halaco had bulldozed from the pond area to make the berms; and (2) the current opinion of an employee of the Oxnard Building and Safety Department that a permit would have been required in 1970 for the grading involved, and for berms that exceeded five feet. The staff also suggested that hazardous material was involved, but acknowledged that the hazardous waste division was still making its analysis, and that the Regional Water Quality Control Board had not found the presence of hazardous substances. The suggestion that the use of the pond involved hazardous material was supported only by asserting that a representative of the Department of Fish and Game felt otherwise (than did the Water Quality Control Board) and noting that there had been a question in 1970 about whether the fluid discharge then being made into the drain was hazardous.
The staff also concluded that a permit had been and was required for expansion of the settling pond, i.e., for extending the northern berm by deposition on it of materials dredged from the pond. The staff reasoned that prior to February 1, 1973, Halaco had been depositing the dredgings within the perimeter of the original pond arid berms, and only after that date began the northern expansion of the berm.
Halaco’s president and general manager testified at the hearing regarding the use of the eastern parcel for a settling pond, the dredging and the deposition operations.
[72]*72The commissioners then voted unanimously to approve the claim of exemption for the developments on the western parcel other than the propane tank. The members divided, denying the claim as to the propane tank in a vote of eight to three.
The members voted by a seven-to-four majority to deny the claim of exemption as to the operation of the settling basin by extension of the berms beyond the lines defined on the 1969 sketch. On a final voice vote the members unanimously passed a motion that Halaco’s current operation not be suspended provided that a timely application was made for a permit to operate on that nonexempt portion of the eastern parcel.18
IV.
The superior court reviewed the Commission decision on Halaco’s petition for writ of mandamus filed pursuant to Code of Civil Procedure section 1094.5. (§ 30802.) Because the Commission itself had declined to hear Halaco’s administrative appeal from the decision of the Regional Commission, the review was of the Regional Commission decision and proceedings.
The applicable substantive principles to be applied in determining a Coastal Act claim of vested right to construct a development were summarized by this court in Avco Community Developers, Inc. v. South Coast Regional Com., supra, 17 Cal.3d 785, 791. “[I]f a property owner has performed substantial work and incurred substantial liabilities in good faith reliance upon a permit issued by the government, he acquires a vested right to complete construction in accordance with the terms of the permit. (,Dob[73]*73bins v. City of Los Angeles (1904) 195 U.S. 223 [49 L.Ed. 169, 25 S.Ct. 18]; Trans-Oceanic Oil Corp. v. Santa Barbara (1948) 85 Cal.App.2d 776, 784 [194 P.2d 148].) Once a landowner has secured a vested right the government may not, by virtue of a change in the zoning laws, prohibit construction authorized by the permit upon which he relied.” Preparatory work will not give rise to a vested right, however, when it is done with knowledge that one or more additional permits will be required for actual construction. The government may apply the laws actually in effect at the time the additional permits are sought. (Id., at p. 793.)
The legal arguments of the parties here require application and extension of the principles considered in Avco because Avco did not involve a claim of vested right to continue a previously lawful but presently nonconforming use of improved property. The vested right claim at issue in Avco was predicated on preparatory expenditures for grading and installation of improvements by a developer who had not yet acquired permits for the planned development. The vested right claimed by Halaco is the right to continue a nonconforming use of improvements already constructed and of which the settling pond and disposal site are integral parts.
The staff of the Regional Commission, and its legal counsel, advised the Regional Commission that in their view Halaco could not acquire a vested right to the use of the settling pond and use of the remainder of the eastern parcel for disposal of dredged material. That advice was based on Halaco’s failure to obtain a grading or special use permit for the development and use of that parcel and reasoning that the operation was not one previously permitted without such permits. Halaco took the position that no additional permits were needed inasmuch as the smelting operation including the use of the pond in the contemplated manner by filling and dredging onto the eastern parcel was an integrated operation permitted under the zoning law; construction permits and special use permits had been granted for the construction and operation of its smelter and foundry;19 and the city in interpreting its own ordinances had determined that Halaco had all necessary permits.
The Regional Commission accepted neither approach. Instead it found that Halaco had acquired a vested right to use and dredge its settling pond [74]*74in the manner in which it had been operated since 1970, but did not have a vested right to deposit dredgings on any part of the eastern parcel beyond the line of the perimeter of the settling pond sketched in the 1969 blueprint submitted by Halaco to the City of Oxnard at the time it inquired whether a permit for construction and use of the pond was required.20
The evidence in the administrative record is undisputed. We have said that in such case, the ultimate conclusion to be drawn from such facts is a question of law (Board of Education v. Jack M. (1977) 19 Cal. 3d 691, 698, fn. 3 [139 Cal.Rptr. 700, 566 P.2d 602]); and have applied that rule even in cases in which the evidence was circumstantial and susceptible of conflicting inferences (see Morrison v. State Board of Education (1969) 1 Cal.3d 214, 238 [82 Cal.Rptr. 175, 461 P.2d 375]; Yakov v. Board of Medical Examiners (1968) 68 Cal.2d 67, 74 [64 Cal.Rptr. 785, 435 P.2d 553]). We have also recognized that where there is substantial evidence to support the decision of an administrative agency, and the inferences drawn from the evidence by an administrative agency are plausible, a reviewing court must uphold the decision and may not reweigh the evidence. (Rivcom Corp. v. Agricultural Labor Relations Bd. (1983) 34 Cal.3d 743, 756-758 [195 Cal.Rptr. 651, 670 P.2d 305].) It follows that where, because a fundamental right is involved the court exercises its independent judgment, the superior court judge may draw contrary inferences. Where the undisputed facts from which the superior court draws an inference do not point to a single conclusion, an appellate court reviewing a decision of the superior court exercising its independent judgment on the weight of the evidence is bound by an inference drawn by the superior court. (Aries Dev. Co. v. California Coastal Zone Conservation Com. (1975) 48 Cal.App.3d 534, [75]*75545 [122 Cal.Rptr. 315].) With respect to the undisputed facts, however, where only the legal effect of those facts is in issue, the conclusions of the trial court are not controlling on appellate review. (Ibid.)
Applying these rules to the instant case we conclude that the judgment of the superior court must be affirmed.
a. The Settling Pond and Water Disposal Site
The superior court concluded that the city, interpreting its own ordinances and the scope of the authorizations granted by the permits issued to Halaco, with full awareness of the nature of Halaco’s operation and the intended development and use of its settling pond and waste disposal site, had determined that Halaco needed no additional permits when it commenced the construction of the pond and use of the waste disposal site.21 [76]*76To the extent that this conclusion is based on inferences drawn from the evidence it is supported by substantial evidence and we are bound by the superior court’s conclusions. The unavoidable legal effect of this finding is a conclusion that the Regional Commission’s determination that Halaco did not have a vested right to use the settling pond and waste disposal site in the manner contemplated in 1970 when construction began is not supported by the weight of the evidence.
b. The Propane Tank.
With the regard to the propane tank the superior court found that “the evidence presented to the Regional Commission . . . showed that with the exception of the 18,000 gallon propane tank, Halaco had constructed and operated its facilities prior to the effective date of the Act. ...” Halaco does not dispute the fact that the propane tank was installed after the effective date of the Coastal Act and the uncontradicted evidence fully supports this finding. The court concluded as a matter of law that the tank constituted placement or erection of solid material in the coastal zone and was therefore subject to the permit requirements of the Coastal Act.
A “development” for which a permit is required under the Coastal Act includes “on land, in or under water, the placement or erection of any solid material or structure.” (§ 30106.) A “ ‘structure’ includes, but is not limited to, any building, road, pipe, flume, conduit, siphon, aqueduct, telephone line, and electrical power transmission and distribution line.” (Ibid.)
Halaco contends that because the tank is personalty and is movable its placement on the property does not come within the statutory permit requirement. It characterizes the tank as equipment whose use is incidental to the smelting process of which it forms an integral part. It was not, however, an integral part of the process prior to 1973 when it was placed on the property. It is, therefore, a change or new development for which a permit was required if it meets the statutory definition of a development.
The evidence offered by Halaco in support of its claim of exemption for the tank is that it was purchased to provide standby propane fuel for the furnaces and forklifts at the foundry. It sits “loosely unattached on concrete saddles” and may be removed by a crane. It is not affixed to the property. [77]*77Halaco elected to install the tank as a less expensive and more convenient alternative to trucking propane onto the site in a trailer tank which would remain on the property until the fuel was consumed at which time a replacement trailer tank would be trucked in.
The record also reflects, however, the issuance of a permit for the installation of the tank issued by the Oxnard Department of Building and Safety. That permit describes the work as an addition to a commercial building, and describes the work to be done in conjunction with the installation as “foundation for tank—100 lin ft blk wall, 4' retainer w/8' blk.” An Oxnard Fire Department permit was issued for “one (1) 18,000 gallon L.P.G. tank and vaporizer to be installed and used in accordance with N.F.P.A. pamphlet # 58.”
Halaco’s suggestion that because the tank is movable and is a substitute for a trailer tank it should be analogized to other equipment for which no permit is required such as automobiles and forklifts is unpersuasive. It is apparent from the acknowledged need to use a crane to install the tank, the construction of “saddles” on which to place it, and associated construction for which the permits were issued, that it is in a very real sense a structure erected on or solid material deposited on the property for which a permit was required. The trial court correctly concluded that the Regional Commission’s denial of the claim of exemption for the tank was proper.
V.
The Commission argues that because the superior court erroneously determined that no findings had been made by the Regional Commission, it exercised its judgment on the basis of assumptions that findings contrary to those recommended by the staff had been made. On that basis it is suggested that the matter must be remanded to the trial court. Alternatively, it is suggested that if no findings were adopted by the Regional Commission the trial court should have remanded the matter to the Regional Commission for the adoption of findings.22
The posture of this case makes remand unnecessary. As we have noted above, the Regional Commission did in its decision make findings of ultimate fact when it determined that Halaco does have a vested right to continue the operation of its foundry and smelting processes, and to the use of the settling pond. In those findings other findings were necessarily implied. [78]*78Inasmuch as the trial court was exercising its independent judgment as to the weight of the evidence, the court was able to assess whether that evidence supported the express and implied findings with respect to all of the individual components of the Halaco application. The court found that the weight of the evidence supported the implicit finding of the Regional Commission that the city was aware of the full extent of Halaco’s plans for the use of the settling pond when Halaco was advised that no permits were needed, and had reconfirmed that conclusion in 1972 when the permit for the new foundry building was granted. The court also found that the weight of the evidence did not support a conclusion that this decision was based on, and no evidence supported a conclusion that the decision was based on, the 1969 sketch. These findings and the inferences drawn from the evidence are supported by substantial evidence.23 The trial court properly ordered issuance of a peremptory writ directing the Regional Commission to approve Halaco’s claim of exemption for all of its operations other than the use of the 18,000-gallon propane tank.
When a court reviewing an adjudicatory decision of an administrative agency determines that the agency decision is not supported by the weight of the evidence, remand for further administrative proceedings is appropriate if the impact of that holding leaves open to the agency any further discretionary powers.
Here, however, the time within which hearings may be held and action taken expired more than five years ago, the administrative record is complete, and the weight of the evidence does not support the Regional Commission’s conclusion that the applicant failed to establish a vested right to continue its use of the settling pond. That conclusion leaves no further discretion to the agency since it necessarily follows that the evidence does support the claim which must, therefore, be approved. The writ directing the Regional Commission to approve the claim of exemption as to the use of the settling pond was properly issued in these circumstances.
VI.
Attorney Fees
Halaco contends that the actions of the Regional Commission in handling its application were so arbitrary and capricious as to warrant an award of [79]*79attorney fees pursuant to Government Code section 800. The trial court concluded, without explanation, that Halaco was not entitled to fees, but was entitled to costs.
Government Code section 800 provides that in an action to review an administrative determination the prevailing complainant may be awarded fees in a reasonable amount not to exceed $1,500 “where it is shown that the award, finding, or other determination of such proceeding was the result of arbitrary or capricious action or conduct by a public entity.” Our review of the administrative record confirms that substantial evidence supports the trial court’s implicit finding that the conduct of the Regional Board in considering Halaco’s application was not wholly arbitrary and capricious.
“The award of attorney’s fees under Government Code section 800 is allowed only if the actions of a public entity or official were wholly arbitrary or capricious. The phrase ‘arbitrary or capricious’ encompasses conduct not supported by a fair or substantial reason (Madonna v. County of San Luis Obispo (1974) 39 Cal.App.3d 57, 62 [113 Cal.Rptr. 916]), a stubborn insistence on following unauthorized conduct (Midstate Theaters, Inc. v. Board of Supervisors (1975) 46 Cal.App.3d 204, 211 [119 Cal.Rptr. 894]), or a bad faith legal dispute (Healdsburg Police Officers Assn. v. City of Healdsburg (1976) 57 Cal.App.3d 444, 457 [129 Cal.Rptr. 216]). The determination of whether an action is arbitrary or capricious is essentially one of fact, within the sound discretion of the trial court. (Mitchell v. State Personnel Bd. (1979) 90 Cal.App.3d 808, 814 [153 Cal.Rptr. 552]).” (Kreutzer v. County of San Diego (1984) 153 Cal.App.3d 62, 78 [200 Cal.Rptr. 322].)
Here, although the superior court concluded that there was no evidence to support the Regional Commission’s decision that Halaco did not have a vested right to continue the use of its settling pond and disposal site, the record refutes any suggestion that the decision was arbitrary and capricious. Rather, it was reached after the members gave serious consideration to the relevant evidence, had difficulty in assessing its legal significance, and in good faith attempted to reconcile what they believed that evidence to show with the advice they received from staff and counsel.
The judgment is affirmed.
Each party shall bear its own costs.
Broussard, J., Lucas, J., and Eagleson (David N.), J.,
Associate Justice, Court of Appeal, Second District, assigned by the Chairperson of the Judicial Council.