Full opinion text
PREGERSON, Circuit Judge: This consolidated appeal of two separate actions requires us to consider the constitutionality of an innovative municipal ordinance enacted by the City of Lodi, California (“Lodi” or “the City”) to remedy hazardous waste contamination within its borders. Fireman’s Fund Insurance Company (“Fireman’s Fund”), Unigard Insurance Company, and Unigard Security Insurance Company (“Unigard”) (collectively “the Insurers”) appeal from the district court’s judgments in favor of Lodi in the Insurers’ separate but related actions for declaratory and injunctive relief. Both Fireman’s Fund and Unigard filed suit to prevent Lodi from enforcing a local ordinance, the Comprehensive Municipal Environmental Response and Liability Ordinance (“MERLO” or “the Ordinance”), an ordinance which permits the City to investigate and remediate the hazardous waste contamination of its soil and groundwater. The Insurers allege that MERLO is preempted by the federal Comprehensive Environmental Response, Compensation and Liability Act (“CERCLA”), 42 U.S.C. §§ 9601-9675, and by various state laws including California’s Carpenter-Presley-Tanner Hazardous Substance Account Act, (“HSAA”), Cal. Health & Safety (“H & S”) Code §§ 25300-25395.15. We have jurisdiction pursuant to 28 U.S.C. § 1291, and we affirm in part, reverse in part, and remand for further proceedings consistent with this opinion. I. BACKGROUND A. The Contamination of Lodi’s Water Lodi first detected the presence of tetrachloroethylene (“PCE”), in its groundwater in April 1989. PCE is a known carcinogen that is often used as a dry-cleaning agent. Groundwater is Lodi’s sole source of drinking water and the primary source of water for agricultural use in California’s Central Valley. Three years later, in 1992, the Central Valley Regional Water Quality Control Board (“RWQCB”) issued a report entitled “Dry Cleaners' — A Major Source of PCE in Ground Water.” The report concluded that the source of the contamination was “the discharge of PCE-containing waste-water i[n]to the sewer lines” by local dry cleaning businesses. The following year, the Department of Toxic Substances Control (“DTSC”) of the California Environmental Protection Agency began investigating the PCE contamination. DTSC is the state agency responsible for ensuring that California’s public health and environment are protected from the harmful effects of hazardous substances. See Cal. H & S Code §§ 25312, 25313, 25350-25359.8. DTSC is authorized to oversee the cleanup of hazardous waste sites by issuing remedial orders and by entering into agreements with “potentially responsible parties” (“PRPs” or “RPs”) to facilitate remediation. DTSC’s investigation revealed that four small businesses were potentially responsible for the PCE-contaminated wastewater that migrated throughout Lodi by land disposal, sewer lines, and city water wells. One business, Lustre-Cal Nameplate Corporation (“Lustre-Cal”) — a manufacturer of color anodized and etched aluminum nameplates and labels- — -is insured by defendant Fireman’s Fund. Another business, Busy Bee Laundry & Cleaners (“Busy Bee”) — a dry cleaner — was a tenant of M & P Investments, which is insured by defendant Unigard. As a result of its investigation, DTSC listed the “Lodi Groundwater Site” as a state hazardous waste site beginning in fiscal year 1993-94. This is significant because listed sites are subject to the “procedures, standards, and other requirements” of HSAA. Cal. H & S Code § 25356(d). After it listed the Lodi Groundwater Site, DTSC began an HSAA-authorized administrative action against selected PRPs, including Lodi, to address the soil and groundwater contamination. B. Lodi’s Investigation and Remediation Strategy In January 1997, Lodi retained the law firm of Zevnik, Horton, Guibord & McGovern, LLP to assist the City in developing a strategy for the investigation and remediation of the PCE contamination. Lodi next initiated a series of events that culminated in the adoption of MERLO. First, in April 1997, Lodi adopted Ordinance No. 1647, which declared the presence of any unpermitted hazardous substance in the environment a per se nuisance. Second, in May 1997, Lodi and DTSC entered into a “Comprehensive Joint Cooperation Agreement” (“Cooperative Agreement” or “Agreement”). Under the Agreement, DTSC and Lodi agreed to “coordinate and cooperate in a single and consolidated effort” to timely investigate and remediate the hazardous substance contamination affecting the City. Consistent with this joint effort, DTSC designated Lodi the “lead enforcement entity” in the cleanup of hazardous substances in and around the City. In exchange, Lodi agreed to “actively seek the input ... of DTSC in the settlement of any environmental enforcement actions” brought by the City pursuant to the Cooperative Agreement, and DTSC agreed “not to independently prosecute any claims [against PRPs] without the full cooperation of ... Lodi.” Lodi also agreed either to clean up the contamination itself or to compel PRPs to do so. The Agreement further states that DTSC retains its authority under HSAA to oversee Lodi’s investigation and remediation efforts, and to review and approve any remediation plan developed by the City. The Agreement also states that Lodi acknowledges that DTSC “may have certain claims against the City of Lodi relating to the released Hazardous Substances, which arise from or relate to the City of Lodi’s design, construction, operation or maintenance of the commercial, industrial and residential storm and sanitary sewer systems operated by the City.” In light of this acknowledgment, Lodi agreed to reimburse DTSC for past and future response costs not to exceed $1,024,549.55, if those costs were not reimbursed by PRPs as a result of Lodi’s investigation and remediation efforts. Nevertheless, Lodi continues to deny being a PRP. Indeed, the Cooperative Agreement between DTSC and Lodi specifically includes a section entitled “No Admission of Liability,” in which Lodi expressly disclaims any admission of liability “arising from or relating to the City of Lodi’s design, construction, maintenance, or operation of sanitary and storm sewer systems.... ” In consideration for Lodi’s agreement to reimburse DTSC, DTSC granted Lodi a “covenant not to sue with respect to claims arising from ... Lodi’s design, construction, operation or maintenance of any storm or sanitary sewer systems.” DTSC also agreed to protect Lodi from contribution actions under CERCLA, 42 U.S.C. § 9613(f)(2), and California’s contribution statute, Cal.Code Civ. Pro. § 877, for “matters addressed” in the Cooperative Agreement. The third event that preceded Lodi’s adoption of MERLO occurred a month after the City entered into the Cooperative Agreement with DTSC. In June 1997, in accordance with the federal Resource Conservation and Recovery Act (“RCRA”), 42 U.S.C. § 6972(b)(2)(A), Lodi issued “Notices of Endangerment” to various PRPs, including Lustre-Cal, which is insured by Fireman’s Fund. Notices of Endangerment may be issued by any citizen and are a condition precedent to filing suit under RCRA’s citizen suit provision. See 42 U.S.C. § 6972(b)(2)(A). The notice to Lus-tre-Cal stated that “the City of Lodi requires that potentially responsible parties, including Lustre-Cal, perform a prompt, comprehensive and cost-effective environmental investigation and remediation of the Site.” The notice also stated that Lus-tre-Cal and the other PRPs were jointly and severally liable for investigation and remediation costs, and that Lodi intended to commence a civil or administrative action against Lustre-Cal unless it settled with the City. Fireman’s Fund Ins. Co. v. City of Lodi, 41 F.Supp.2d 1100, 1105 (E.D.Cal.1999). Finally, on August 6, 1997, Lodi’s City Council enacted the “comprehensive municipal environment response and liability ordinance” as required by the Cooperative Agreement. Ordinance 1650 — commonly known as MERLO — sets forth a comprehensive remedial liability scheme modeled on CERCLA and HSAA. MERLO specifically provides Lodi with municipal authority to investigate and remediate existing or threatened environmental nuisances affecting the City, and to hold PRPs or their insurers liable for the cost of the City’s nuisance abatement activities. See generally MERLO §§ 8.24.010-8.24.090. In order to facilitate this effort, MER-LO: (1) authorizes Lodi to demand the production of documents related to environmental contamination or to any PRP’s ability to pay for investigation and abatement, id. § 8.24.050; (2) creates an administrative hearing process subject to judicial review to resolve liability issues, id. at § 8.24.060; (3) authorizes Lodi to initiate municipal enforcement actions against PRPs, id. at § 8.24.080; (4) authorizes Lodi to bring direct actions against insurers of insolvent PRPs that would resolve the PRP’s liability and the insurers’ coverage obligations in one proceeding, id. at § 8.24.090(B); and (5) creates a “Comprehensive Environmental Response Fund” to be used for the investigation and abatement of environmental nuisances in and around Lodi, id. at § 8.24.070. On November 17, 1999, Lodi’s City Council repealed Ordinance 1650 and reenacted an amended version of MERLO as Ordinance No. 1684. The amended version of MERLO became effective on December 17, 1999. Because we apply the law in effect at the time of decision, we must decide the issues raised in these related appeals based on the current version of MERLO. See Bradley v. Richmond Sch. Bd., 416 U.S. 696, 711, 94 S.Ct. 2006, 40 L.Ed.2d 476 (1974). C. Procedural History of the Present Actions As set forth above, this consolidated appeal involves two separate but related challenges to MERLO — one brought by Unigard, and a second brought by Fireman’s Fund. Because the two lawsuits raise many of the same issues, including the question whether MERLO is preempted by CERCLA or HSAA, we have consolidated the cases for purposes of this appeal. Nevertheless, the cases have distinct procedural histories and come to us on appeal from separate rulings by the district court. 1. The Origins of the Unigard and Fireman’s Fund Actions Shortly after enacting MERLO, and pursuant to its authority under MERLO section 8.24.050, Lodi served Unigard with certain Information Gathering Demands (“Demands”). The Demands stated that Unigard is the insurer of M & P Investments, which may have incurred liability for the PCE contamination as a result of dry cleaning business operations on Lodi property. The Demands ordered Unigard to produce documents related to endorsements in the policy that Unigard issued to M & P Investments. Unigard responded to the Demands with various objections, and the City responded to Unigard’s objections by filing a criminal complaint against Unigard in state court. Unigard responded, in turn, by filing a writ petition in Superior Court, requesting a stay of the criminal proceeding. The Superior Court granted Unigard’s petition and issued a stay to provide Unigard the opportunity to challenge the legality of MERLO in a non-criminal proceeding. Because the writ proceeding provided Lodi with an adequate forum to litigate its claims against Unigard, the state court dismissed Lodi’s criminal complaint against Unigard in May 1998. Also in May 1998, Lodi filed an abatement action pursuant to its authority under MERLO against Unigard’s insured, M & P Investments. Three weeks later, on May 21, 1998, Unigard filed the present action in United States District Court for the Northern District of California. In its complaint, Unigard alleges that Lodi adopted MERLO in order to shift its own liability for the PCE contamination to the insurers of other PRPs. Unigard’s complaint further alleges that MERLO: (1) violates the Supremacy Clause of the United States Constitution because it is preempted by CERCLA; (2) violates Article 11 of the California State Constitution because it is preempted by HSAA and California Insurance Code § 11580; and (3) violates the Contracts Clause of the United States Constitution. After abstaining from deciding certain claims unrelated to this appeal, the district court issued an order to show cause why Unigard’s action should not be transferred to the Eastern District of California. The district court ultimately found that Uni-gard’s remaining claims “have an insufficient connection to the Northern District of California” and transferred the action to the Eastern District of California. All of Unigard’s claims were dismissed prior to the transfer, with the exception of the federal and state preemption claims, and the federal contracts clause claim. Meanwhile, on August 6, 1998, Fireman’s Fund filed a similar declaratory and injunctive relief action against Lodi in the United States District Court for the Eastern District of California. In addition to naming Lodi as a defendant, Fireman’s Fund also named: (1) Lodi’s Mayor, Jack Sieglock, in his official capacity; (2) MER-LO Enforcement Officers Richard C. Pri-ma, Jr. and Fran E. Forkas in their official capacities; (3) Lodi City Attorney Randall A. Hays in his official and individual capacities; and (4) Michael C. Donovan and Zevnik Horton Guibord & McGovern, LLP (collectively, the “Law Firm”), private attorneys acting as assistant city attorneys for Lodi, in their official and individual capacities. Like Unigard’s complaint, the Fireman’s Fund complaint alleges, inter alia, that MERLO: (1) violates the Supremacy Clause of the United States Constitution; (2) violates Article 11 of the California State Constitution because it is preempted by HSAA and California Insurance Code § 11580; and (3) impairs Fireman’s Fund’s right to contract under both the United States Constitution and the California State Constitution. On August 24, 1998, Fireman’s Fund, joined by Unigard, moved for a preliminary injunction prohibiting Lodi from enforcing MERLO. While the Insurers’ preliminary injunction motion was pending, Lodi and its officers moved, in both actions, to dismiss the Insurers’ complaints pursuant to Federal Rule of Civil Procedure 12(b)(1) for lack of subject matter jurisdiction, and Federal Rule of Civil Procedure 12(b)(6) for failure to state a claim. At the same time, Fireman’s Fund filed a motion for partial summary judgment and for a permanent injunction to enjoin Lodi from enforcing MERLO. After extensive briefing by all parties, the district court held a joint hearing on all motions in both cases on December 4, 1998. Following the hearing, the district court issued two written decisions — one in the Unigard action and a second in the Fireman’s Fund action. 2. The Unigard Decision In an unpublished decision filed on March 5, 1998, the district court found Unigard’s claims ripe for review because “the content of [MERLO] is clear as are the City’s intentions to enforce the Ordinance against Unigard.” Unigard Ins. Co. v. City of Lodi, No. Civ. S. 98-1712-FCD-JFM at *5 (E.D.Cal. Mar. 5, 1998). The district court also found that Unigard has standing to bring the present action, id. at 6, and that MERLO is not preempted by CERCLA, id. at 6-13. Finally, the district court abstained under the Pullman abstention doctrine from deciding whether MERLO was preempted by state law. Id. at 14-15. Based on these rulings, the district court granted Lodi’s motion to dismiss Unigard’s federal preemption claim and dismissed without prejudice Unigard’s state preemption and federal contracts clause claims. Unigard timely appeals the district court’s ruling concerning only the federal preemption issue. 3. The Fireman’s Fund Decision In a published opinion filed on February 25, 1999, the district court dismissed Fireman’s Fund’s claims against the individual defendants in their official capacities as “duplicative of the claims against the City.” Fireman’s Fund Ins. Co. v. City of Lodi, 41 F.Supp.2d 1100, 1106 (E.D.Cal.1999). The district court also held that the defendants sued in their individual capacities are entitled to qualified immunity. Id. at 1107. The rulings on the remaining issues — including ripeness, standing, and federal and state preemption — were identical to those rulings in the Unigard action. Id. at 1107-13. The district court found that: (1) Fireman’s Fund’s claims are ripe; (2) Fireman’s Fund has standing to bring the instant action; and (3) MERLO is not preempted by CERCLA. Again, the district court abstained from deciding whether MERLO is preempted by HSAA based on the doctrine of Pullman abstention. Based on these rulings, the district court denied Fireman’s Fund’s motion for partial summary judgment and a permanent injunction, dismissed the individual defendants and the Law Firm from the action, dismissed the federal preemption claim against Lodi, and abstained from ruling on the state preemption claim. The district court dismissed the state preemption and remaining constitutional claims without prejudice. Fireman’s Fund timely appeals the district court’s rulings concerning federal and state preemption, and the district court’s dismissal of the official capacity claims against the individual defendants. II. STANDARD OF REVIEW We review de novo a district court’s decision to grant or deny a motion to dismiss pursuant to Federal Rule of Civil Procedure 12(b)(6). Gonzalez v. Metropolitan Transp. Auth., 174 F.3d 1016, 1018 (9th Cir.1999). In reviewing the complaint, all factual allegations “are taken as true and construed in the light most favorable to [plaintiffs.” Epstein v. Washington Energy Co., 83 F.3d 1136, 1140 (9th Cir.1999). Similarly, we review de novo whether this case meets the requirements of the Pullman abstention doctrine. Martinez v. Newport Beach City, 125 F.3d 777, 780 (9th Cir.1997). The district court has no discretion to abstain in cases that do not meet the requirements of the abstention doctrine being invoked. Id. If the requirements for Pullman abstention are satisfied, we review for an abuse of discretion the district court’s decision to abstain from deciding the state law preemption question. Id. III. STATUTORY OVERVIEW Before reaching the merits of the Insurers’ arguments on appeal, because of the complexity of the claims involved in this case, it is useful to review briefly the three statutory schemes that are germane to this lawsuit: (1) CERCLA, the primary federal statute dealing with the cleanup of hazardous waste; (2) HSAA, the primary state statute dealing with the cleanup of hazardous waste in the State of California; and (3) MERLO, the Lodi ordinance at issue in this case. A. CERCLA Congress enacted CERCLA in 1980 “to provide a mechanism for the prompt and efficient cleanup of hazardous waste sites.” United States v. City of Denver, 100 F.3d 1509, 1511 (10th Cir.1996). CERCLA has two overriding objectives: facilitating the timely cleanup of hazardous waste sites and making polluters pay for the damage that they caused. Stanton Road Assoc. v. Lohrey Enter., 984 F.2d 1015, 1019 (9th Cir.1993). CERCLA directs the EPA to produce a National Priorities List (“the List”), which contains those sites that the EPA has determined are most in need of remediation. 42 U.S.C. § 9605(a)(8)(B) (1994); see also ARCO Envtl. Remediation, L.L.C v. Dep’t of Health and Envtl. Quality, 213 F.3d 1108, 1111 n. 2 (9th Cir.2000). Only listed sites are eligible to receive federal Superfund dollars. See State of New York v. Shore Realty Corp., 759 F.2d 1032, 1046 (2d Cir.1985). As of the date of this opinion, the EPA has not included the Lodi Groundwater site on the List. Once the EPA includes a certain hazardous waste site on the List, CERCLA directs the EPA to prepare a Remedial Investigation and Feasibility Study to “define the nature and extent of the threat ... and to evaluate proposed remedies.” United States v. Akzo Coatings of Am., Inc., 949 F.2d 1409, 1417 (6th Cir.1991). If the EPA determines that CERCLA requires remediation of the site, “it must publish a proposed remedial action plan ... and provide an opportunity for [public] comment. The EPA then issues a Record of Decision ... setting forth the remedy selected for the site.” Id. (citations omitted). CERCLA permits the cleanup efforts to be financed in one of two ways: First, the PRPs are usually given the option of entering into a settlement agreement with the EPA.... The agreement, which is in the form of a consent decree, consists of a promise by the settling PRPs to perform and finance the cleanup action themselves.... Second, in situations where the the PRPs fail to settle with the EPA, the EPA may then intervene and commence the cleanup itself. The EPA’s cleanup action is financed through the use of monies allocated to the Superfund. After the response action has been completed, the EPA seeks recovery of all the cleanup costs from the PRPs under the cost recovery provisions of CERC-LA. Peter F. Sexton, Super Fund Settlements: The EPA’s Role, 20 Conn. L.Rev. 923, 925 (1988) (footnotes omitted); see also 3550 Stevens Creek Assoc. v. Barclays Bank of California, 915 F.2d 1355, 1357 (9th Cir.1990). “In order to be held liable for cleanup costs under CERCLA, a party must fall within one of the four classes of PRPs identified in 42 U.S.C. § 9607(a)(l)-(4)”: (1) current owners and operators of hazardous waste facilities; (2) former owners and operators of hazardous waste facilities; (3) any person who arranged or arranges for the disposal or treatment of hazardous waste; and (4) any person who accepted or accepts hazardous waste for the purpose of transporting it to a disposal facility. Bancroft-Whitney, California Civil Practice, Environmental Litigation, § 3:28 (1993); 42 U.S.C. § 9607(a)(l)-(4); 40 C.F.R. § 35.6015(a)(32). We have interpreted CERCLA to hold PRPs strictly liable for the investigation and remediation of hazardous waste sites. Moreover, like many of our sister circuits, we have also held that CERCLA liability is joint and several. Atchison Topeka & Santa Fe Ry. Co. v. Brown & Bryant, Inc., 159 F.3d 358, 362 (9th Cir.1998). This means that all PRPs are assigned liability for the whole amount of the cleanup costs, and then permitted to allocate the costs amongst themselves, and other unnamed, but responsible parties. The rationale for joint and several liability is to create an incentive for named PRPs to search out other PRPs, so as to make all responsible polluters pay for cleanups. Sarah W. Rubinstein, CERCLA’s Contribution to the Federal Brownfields Problem: A Proposal for Federal Reform, 4 U. Chi. Sch. Roundtable 149, 152 (1997). Although there are circumstances under which municipalities may be considered PRPs under CERCLA’s liability scheme, see, e.g., City of Fresno v. NL Indust., 1995 WL 641983 (E.D.Cal.1995), it is not clear whether a municipality may be considered a PRP solely as a result of operating a municipal sewer system. Compare Lincoln Prop., Ltd. v. Higgins, 823 F.Supp. 1528, 1538, 1539-44 (E.D.Cal.1992) (holding that a municipal sewer system that leaked hazardous waste could rely on a third-party defense to avoid liability under CERCLA), with Westfarm Assoc. Ltd. P’ship v. Washington Suburban Sanitary Comm’n, 66 F.3d 669, 675-80 (4th Cir.1995) (holding that a municipal sewer system is liable for the acts of a third party that discharged hazardous waste into the system). Under CERCLA, the cleanup of listed hazardous waste sites must be consistent with the National Contingency Plan (“NCP”). The NCP is promulgated by the EPA, and “specifies the roles of the federal and state governments in responding to hazardous waste sites, and establishes the procedures for making cleanup decisions.” City of Denver, 100 F.3d at 1511. The burden of establishing that the cleanup process is consistent with the NCP depends on whether the plaintiff in a CERCLA action is the government or a private party: “While the United States government, or a[S]tate or Indian tribe, can obtain ‘all costs of removal or remedial action ... not inconsistent with the [NCP],’ any other person can obtain ‘other necessary costs of response ... consistent with the [NCP].’ ” Washington State Dep’t of Transp. v. Washington Natural Gas Co., 59 F.3d 793, 799 (9th Cir.1995) (citing 42 U.S.C. § 9607(a)(2), (a)(4)(A)-(B)) (emphasis added). In other words, where “the United States government, a[S]tate, or an Indian tribe is seeking recovery of response costs, consistency with the NCP is presumed,” and the burden is on the defendant to rebut the presumption of consistency by establishing that the plaintiffs response action was arbitrary and capricious. Id. However, “any ‘other person’ seeking response costs under [CERCLA] must prove that its actions are consistent with the NCP.” Id. CERCLA was amended in 1986 by the Superfund Amendments and Reauthorization Act of 1986 (“SARA”), 42 U.S.C. §§ 9601-9675. - SARA strengthened CERCLA in two significant ways. First, SARA codified a statutory right of contribution among PRPs. Under SARA, “[a]ny person may seek contribution from any other person who is liable or potentially liable under [CERCLA as a PRP].” 42 U.S.C. § 9613(f)(1). “In resolving contribution claims, the court may allocate'response costs among liable parties using such equitable factors as the court determines are appropriate.” Id. Second, SARA codified various incentives to encourage PRPs to settle quickly with the EPA. See Bedford Affiliates v. Sills, 156 F.3d 416, 427 (2d Cir.1998). Under SARA, PRPs “who choose to settle are granted protection from contribution actions being asserted against them under [CERLCA], but retain the right to bring contribution actions against other non-settling parties.” Id. (citing 42 U.S.C. § 9613(f)(3)(B)). “[SARA] further provides that the amount recoverable from the remaining non-settling parties is reduced only by the amount of the settlement.” Id. (citing 42 U.S.C. § 9613(f)(2)). “Hence, [PRPs] who choose to settle gain protection from contribution, enjoy potentially favorable settlement terms, and retain the ability to seek contribution from other defendants. Those responsible parties who choose not to settle are barred from seeking contribution from the settling parties and thereby face potentially disproportionate liability.” Id. (citing In re Reading Co., 115 F.3d 1111, 1119 (3rd Cir.1997)); see also 42 U.S.C. § 9622(h)(4). B. HSAA HSAA, which is commonly referred to as the “State Superfund Law,” mirrors CERCLA in many respects. Acme Fill Corp. v. Althin CD Med., Inc., 1995 WL 822665 at *5 (N.D.Cal.1995). Like CERCLA, HSAA “imposes cleanup obligations and provides private cost recovery rights substantially identical to those obligations imposed and rights granted under CERCLA.” Donna R. Black, Potential Environmental Liabilities in Corporate Acquisitions, 894 PLI/Corp 543, 546 (June-July 1995). HSAA also relies on CERCLA’s definition of PRPs. Bruce P. Howard, et al., CERCLA and Similar State Laws: Overview and Recent Developments, 832 PLI/Corp 531, 551(Dec.-Jan.l993). However, HSAA differs from CERCLA in that “HSAA liability may be apportioned according to fault,” whereas liability under CERCLA is joint and several. Id. HSAA is administered by DTSC, which employs a listing process similar to that used by the EPA at the federal level. As discussed above, DTSC listed the Lodi Groundwater Site as a hazardous waste site beginning in fiscal year 1993-94. C. MERLO MERLO is modeled on both CERCLA and HSAA, and was adopted by Lodi with the full cooperation and encouragement of the Department of Toxic Substances Control (“DTSC”). MERLO incorporates many of the standards employed by CERCLA and HSAA. For example, MER-LO utilizes the CERCLA and HSAA definition of who may be considered a PRP, see MERLO § 8.24.040(A)(1), and, like CERCLA, the scope of liability under MERLO is joint and several, see MERLO § 8.24.040(F). Lodi asserts that it enacted MERLO to empower the City — the governmental entity most intimately connected with the soil and groundwater contamination — to facilitate and oversee the remediation of its soil and groundwater. The Insurers allege, however, that Lodi enacted MERLO to avoid paying its fair share as a PRP for remediating the PCE contamination. According to the Insurers, Lodi is properly considered a PRP because the City’s poorly designed and maintained sewer system allowed the PCE-contaminated wastewater to migrate easily throughout the region. Lodi disputes these assertions. According to Lodi, “the City does not concede that it is a potentially responsible party at this site merely because hazardous substances discharged into its sewers by other parties leaked out into the environment.” IY. ANALYSIS On appeal, Fireman’s Fund asserts that the district court erred in abstaining from deciding whether MERLO is preempted by various state laws, and Fireman’s Fund and Unigard argue that MERLO is in fact preempted by state and federal law. We find that the district court erred in abstaining from deciding whether MERLO is preempted by state law. Because the state law preemption analysis resembles the federal preemption analysis, we consider whether MERLO is preempted by federal law in conjunction with the state law preemption question. We conclude by finding that although a few sections of MERLO are preempted by state and federal law under the doctrine of conflict preemption, the majority of the Insurers’ preemption arguments lack merit. In addition, Fireman’s Fund appeals the district court’s decision dismissing its official capacity claims against three individual defendants. We agree with Fireman’s Fund and reinstate those claims. A. ABSTENTION Fireman’s Fund first argues that the district court erred in abstaining from deciding its state preemption claim, and in dismissing its remaining federal and state constitutional claims on this basis. We agree. The district court decided sua sponte not to exercise its jurisdiction over Fireman’s Fund’s state law preemption claim under the doctrine of Pullman abstention. First articulated by the Supreme Court in Railroad Comm’n of Tex. v. Pullman Co., 312 U.S. 496, 61 S.Ct. 643, 85 L.Ed. 971 (1941), “Pullman abstention is an equitable doctrine that allows federal courts to refrain from deciding sensitive federal constitutional questions when state law issues may moot or narrow the constitutional questions.” The San Remo Hotel, 145 F.3d at 1104. Like all abstention doctrines, Pullman abstention “is an extraordinary and narrow exception to the duty of a district court to adjudicate a controversy” properly before it. Canton v. Spokane Sch. Dist. # 81, 498 F.2d 840, 845 (9th Cir.1974) (citing Allegheny County v. Frank Mashuda Co., 360 U.S. 185, 188, 79 S.Ct. 1060, 3 L.Ed.2d 1163 (1959)). Three factors must be present before a district court may abstain under the Pullman doctrine: “(1) the complaint must involve a ‘sensitive area of social policy’ that is best left to the states to address; (2) ‘a definitive ruling on the state issues by a state court could obviate the need for [federal] constitutional adjudication by the federal court’; and (3) ‘the proper resolution of the potentially determinative state law issue is uncertain.’ ” Cedar Shake and Shingle Bureau v. City of Los Angeles, 997 F.2d 620, 622 (9th Cir.1993) (quoting Kollsman v. City of Los Angeles, 737 F.2d 830, 833 (9th Cir.1984)). If a court invokes Pullman abstention, it should stay the federal constitutional question “until the matter has been sent to state court for a determination of the uncertain state law issue.” Erwin Chemerin-sky, Federal Jurisdiction, § 12.2.1, at 737 (3d ed.1999). The district court concluded that all three Pullman factors were present in this case. Upon careful review, however, we find that both the first and third factors are lacking. Because there is no discretion to abstain in cases that do not meet the requirements of the abstention doctrine being invoked, Martinez, 125 F.3d at 780, we hold that the district court erred in abstaining from ruling on Fireman’s Funds’ state law preemption claim. As set forth above, the first Pullman factor requires us to find that “the complaint ... involve[s] a sensitive area of social policy that is best left to the states to address.” Cedar Shake and Shingle Bureau, 997 F.2d at 622 (internal quotation omitted). The district court found that this factor was satisfied because this case involves “an area of serious local concern about which the DTSC has expressed no opinion and into which federal intrusion is undesirable.” Fireman’s Fund, 41 F.Supp.2d at 1112. We respectfully disagree. Although “the interpretation of a local ordinance which enables the City to pay for hazardous waste remediation it could not otherwise afford” is undoubtedly an area of “serious local concern,” it cannot truly be said that “federal intrusion is undesirable.” Id. Indeed, the federal government has definitively entered the field of hazardous waste remediation by enacting CERCLA. Moreover, the text of CERCLA makes clear that Congress envisioned a partnership between various levels of government in addressing the complex and costly problems associated with hazardous waste remediation. See, e.g., 42 U.S.C. §§ 9614(a), 9652(d), 9659(h). In addition, although DTSC has not issued a formal written opinion regarding MERLO, it cannot truly be said that “DTSC has expressed no opinion” about the Lodi ordinance. Fireman’s Fund, 41 F.Supp.2d at 1112. On the contrary, by entering into the Cooperative Agreement with Lodi, DTSC implicitly approved of the City’s efforts to enact MERLO. Indeed, the Cooperative Agreement itself obligated Lodi to adopt MERLO as part of its municipal remediation strategy. Specifically, under the terms of the Agreement, Lodi agreed to: utiliz[e], as appropriate, the full range of its remedial and regulatory injunctive and cost recovery authority under federal, state and municipal law, to compel the complete, timely, competent, cost-effective performance of the Work in full compliance with federal, state and local law, specifically including the NCP, as appropriate. These enforcement efforts will include ... the -prompt enactment and enforcement of a comprehensive municipal environmental response ordinance which shall enact into municipal law additional legal authorities to appropriately supplement the City of Lodi’s already extensive environmental response authority under federal, state and local law.... (emphasis added). Thus, MERLO was enacted with the full cooperation and encouragement of DTSC. We therefore find that the district court erred in concluding that the first Pullman abstention factor has been satisfied in this case. Although our finding that the first Pullman factor has not been satisfied is sufficient to support our decision to reverse the district court on this issue, we note that the third Pullman abstention factor is also lacking in this case. As set forth above, the third Pullman factor requires us to find that “the proper resolution of the potentially determinative state law issue is uncertain.’ ” Cedar Shake and Shingle Bureau, 997 F.2d at 622 (internal quotation and citation omitted). The district court concluded that the determinative state law issue in this case is whether MERLO is preempted by state law because it duplicates or contradicts HSAA. Fireman’s Fund, 41 F.Supp.2d at 1112-13. The district court ultimately found that because “California courts have not spoken definitively in this matter,” the third Pullman factor has been satisfied. Id. at 1113. Again, we respectfully disagree. The fact that a state court has not ruled on the precise issue at stake in this case does not mean that the proper resolution of the state law issue is “uncertain.” Constantineau, 400 U.S. at 439, 91 S.Ct. 507; see also Pearl Invest. Co. v. City & County of San Francisco, 774 F.2d 1460, 1465 (9th Cir.1985) (holding that uncertainty for Pullman abstention means that a federal court cannot predict with any confidence how a state’s highest court would decide an issue of state law). On the contrary, California has left several guideposts to assist us with the state law preemption analysis. First, the California Supreme Court has provided us with guidance in determining when a local regulation is preempted by state law. See, e.g., People ex rel. Deukmejian v. County of Mendocino, 36 Cal.3d 476, 485, 204 Cal.Rptr. 897, 683 P.2d 1150 (1984). Second, HSAA itself provides us with substantial guidance by expressly recognizing the continuing viability of supplementary municipal legislation. See, e.g., Cal. H & S Code § 25356.6(a). Finally, we also have the additional benefit of a recent decision by the California Supreme Court that relates to the present litigation. On July 24, 2000, after the district court’s decision in the present case, the California Supreme Court decided Connecticut Indemnity Co. v. Superior Court, 23 Cal.4th 807, 98 Cal.Rptr.2d 221, 3 P.3d 868 (2000), a case in which Fireman’s Fund and other insurers of PRPs challenged Lodi’s decision to issue legislative subpoenas pursuant to its authority under MERLO. Id. at 226-28, 3 P.3d 868. Specifically, Fireman’s Fund argued that Lodi exceeded its authority under state law in issuing the subpoenas. Fireman’s Fund also argued that Lodi issued the subpoenas for an improper purpose, i.e., as a tool to gather sufficient information to file suit against the PRPs and their insurers. The California Supreme Court upheld Lodi’s authority under MERLO to issue the legislative subpoenas. Speaking for a unanimous court, Chief Justice George stated that: [Controlling authority establishes that a city may issue legislative subpoenas when it has been authorized by ordinance or similar enactment to do so, when issuance of the subpoenas serves a valid legislative pui-pose, and when the witnesses or material subpoenaed are pertinent to the subject matter of a legislative investigation. We conclude ... that the city satisfied these requirements in this case. Id. at 223, 3 P.3d 868. In so holding, the California Supreme Court specifically found that: The subject matter of the [City’s] investigation, an environmental public nuisance amounting to, as the trial court put it, “a tremendous and serious groundwater contamination problem” within Lodi’s city limits, obviously is an area over which the city council has authority and responsibility both to legislate and to appropriate. $ ‡ ‡ H* ‡ ‡ As has been observed, “ ‘[i]t is difficult to imagine any interest that [a legislative entity] could have that would be more compelling ... than its interest in determining the availability of funds for the cleanup of hazardous substances located within its boundaries.’ ” We find Lodi’s asserted legislative interests to be legitimate, and not mere pretext or sham. Id. at 226-27, 3 P.3d 868 (quoting Ford Motor Co. v. Insurance Co. of North Am., 35 Cal.App.4th 604, 41 Cal.Rptr.2d 342, 348 (1995)). Thus, the California Supreme Court has acknowledged the serious nature of Lodi’s groundwater contamination problem and has generally affirmed the authority and responsibility of Lodi to regulate this contamination as an “environmental public nuisance.” Id. at 226, 3 P.3d 868. Because we are not without guidance from the state courts in addressing the state law preemption question, we find that the third Pullman abstention factor is not satisfied in this case. What is more, the third Pullman factor is not satisfied for the additional reason that we cannot say that there is a “reasonable possibility that the state court’s clarification of state law might obviate the need for the federal constitutional ruling.” Chemerinsky, supra, at 742^43. On the contrary, we are confident that a definitive decision from the state court on the state-law preemption question would do little to relieve us of our duty to resolve the federal constitutional issues in this case. First, as discussed in Section IV.B.3. infra, it is fairly clear that MERLO as a whole is consistent with state law, and that municipalities in California may enact local ordinances which allow them to take an active role in remediating local hazardous waste contamination. Second, even if the state court were to find, as we do infra, that a few specific provisions of MERLO are preempted, such a finding would only invalidate those specific provisions. The bulk of MERLO would remain in effect, as would our obligation to consider Fireman’s Funds’ federal constitutional claims. Pullman abstention is therefore inappropriate. In sum, because we find that both the first and the third Pullman factors are lacking, we reverse the district court’s decision to abstain from deciding Fireman’s Fund’s state law preemption claim. We proceed now to the merits of the federal and state preemption analysis. B. PREEMPTION Fireman’s Fund argues that MERLO is preempted by state law. In addition, both Fireman’s Fund and Uni-gard argue that MERLO is preempted by federal law. After briefly reviewing the doctrines of federal and state preemption, we consider each of the Insurers’ preemption arguments in turn. 1. Overview of Federal Preemption Under the Supremacy Clause of the United States Constitution, state laws that “interfere with, or are contrary to the laws of Congress” are preempted and are therefore invalid. Gibbons v. Ogden, 22 U.S. (9 Wheat) 1, 211, 6 L.Ed. 23 (1824). “Congressional intent governs our determination of whether federal law preempts state law. If Congress so intends, ‘[p]re-emption ... is. compelled whether Congress’ command is explicitly stated in the statute’s language or implicitly contained in its structure and purpose.” Boyes v. Shell Oil Prods. Co., 199 F.3d 1260, 1267 (11th Cir.2000) (quoting Gade v. National Solid Wastes Mgmt. Ass’n, 505 U.S. 88, 96, 112 S.Ct. 2374, 120 L.Ed.2d 73 (1992) (plurality)). The Supreme Court has recognized three types of federal preemption: (1) express preemption, where the statute contains “explicit pre-emptive language,” (2) field preemption, “where the scheme of federal regulation is so pervasive as to make reasonable the inference that Congress left no room for the States to supplement it,” and (3) conflict preemption, “where compliance with both federal and state regulations is a physical impossibility, or where state law stands as an obstacle to the accomplishment and execution of the full purposes and objectives of Congress.” Id. (citing Gade, 505 U.S. at 96, 112 S.Ct. 2374 (emphasis added)). “Although these categories provide a useful analytic framework, they are not ‘rigidly distinct.’ ” Industrial Truck Ass’n v. Henry, 125 F.3d 1305, 1309 (9th Cir.1997). “When considering [preemption], ‘we start with the assumption that the historic police powers of the States were not to be superseded by the Federal Act unless that was the clear and manifest purpose of Congress.’ ” Wisconsin Pub. Intervenor v. Mortier, 501 U.S. 597, 604, 111 S.Ct. 2476, 115 L.Ed.2d 532 (1991) (quoting Rice v. Santa Fe Elevator Corp., 331 U.S. 218, 230, 67 S.Ct. 1146, 91 L.Ed. 1447 (1947)). Moreover, we are “highly deferential” to local legislation in areas such as environmental regulation, which “traditionally has been a matter of state authority.” Exxon Mobil Corp. v. United States Env’t Prot. Agency, 217 F.3d 1246, 1255 (9th Cir.2000). Finally, “for [ ] purposes of the Supremacy Clause, the constitutionality of local ordinances is analyzed the same way as that of statewide laws.” Hillsborough County v. Automated Med. Labs., Inc., 471 U.S. 707, 713, 105 S.Ct. 2371, 85 L.Ed.2d 714 (1985) (internal citations omitted). 2. Overview of State Preemption California preemption doctrine is based on Article XI, section 7 of the California Constitution, which states that “[a] county or city may make and enforce within its limits all local, police, sanitary, and other ordinances and regulations not in conflict with general laws.” Cal. Const., art. XI, § 7 (emphasis added); Sherwin-Williams Co. v. City of Los Angeles, 4 Cal.4th 893, 16 Cal.Rptr.2d 215, 217, 844 P.2d 534 (1993). The California Supreme Court has held that State law is “in conflict with” or preempts local law if the local law “duplicates, contradicts, or enters an area fully occupied by general law, either expressly or by legislative implication.” Sherwin-Williams, 16 Cal.Rptr.2d. at 217, 844 P.2d 534. As the court further explained: Local legislation is “duplicative” of general law when it is coextensive therewith. Similarly, local legislation is “contradictory” to general law when it is inimical thereto. Finally, local legislation enters an area that is “fully occupied” by general law when the Legislature has expressly manifested its intent to “fully occupy” the area, or when it has impliedly done so ... Id. at 218, 844 P.2d 534 (internal quotations and citations omitted). Thus, with the exception of the concept of preemption by duplication which has no federal analogue, California’s preemption doctrine is similar to federal preemption law. With this background in mind, we proceed to the merits of the federal and state preemption analysis. 3. Preemption Analysis a. Express Preemption Neither CERCLA nor HSAA expressly preempts local law, and the Insurers do not argue otherwise. Fireman’s Fund, 41 F.Supp.2d at 1109 (citing Bedford Affiliates, 156 F.3d at 426; Witco Corp. v. Beekhuis, 38 F.3d 682, 687 (3d Cir.1994); Akzo Coatings, 949 F.2d at 1455; City of Denver, 100 F.3d at 1512); see also Cal. H & S Code § 25356.6(a). b. Field Preemption Similarly, the Insurers do not argue that CERCLA alone preempts the field by implication. Indeed, as the Insurers acknowledge, CERCLA contains three separate savings clauses to preserve the ability of states to regulate in the field of hazardous waste cleanup. First, CERCLA § 114(a) states that “[n]othing in this chapter Shall be construed or interpreted as preempting any State from imposing any additional liability or requirements with respect to the release of hazardous substances within such State.” 42 U.S.C. § 9614(a). Second, CERCLA § 302(d) states that “[n]othing in this chapter shall affect or modify in any way the obligations or liabilities of any person under other Federal or State law, including common law, with respect to release of hazardous substances or other pollutants or contaminants....” 42 U.S.C. § 9652(d). And third, CERCLA § 310(h) states that “[t]his chapter does not affect or otherwise impair the rights of any person under Federal, State, or common law, except with respect to the timing of review as provided in section 9613(h),” a CERCLA provision that is not at issue in the present case. 42 U.S.C. § 9659(h). Based on these provisions, courts have repeatedly held that “CERCLA does not completely occupy the field of environmental regulation.” ARCO, 213 F.3d at 1114. Because the Insurers cannot argue that CERCLA alone occupies the field, the Insurers instead argue that CERCLA and HSAA, together, occupy the field. According to the Insurers, CERCLA explicitly authorizes states, but not municipalities, to impose additional requirements regarding the cleanup of hazardous substances. The Insurers therefore maintain that MERLO is preempted by the combined impact of CERCLA and HSAA under the doctrine of field preemption. The district court rejected this argument. Relying on the Supreme Court’s decision in Wisconsin Public Intervenor v. Mortier, 501 U.S. 597, 111 S.Ct. 2476, 115 L.Ed.2d 532 (1991), the district court held that the term “state” as used in CERCLA is broad enough to include political subdivisions such as Lodi. Fireman’s Fund, 41 F.Supp.2d at 1110. As the district court explained, “the exclusion of political subdivisions cannot be inferred from [CERC-LA’s] express authorization to the ‘State[s]’ because political subdivisions are components of [states].” Id. (quoting Mortier, 501 U.S. at 608, 111 S.Ct. 2476). The district court further noted that because California could simply re-delegate its authority under CERCLA to Lodi, the fact that CERCLA does not specifically refer to political subdivisions is inconsequential. We agree with the district court. The Insurers’ argument is based on the premise that, by referring to states but not political subdivisions in the text of the statute, Congress intended CERCLA to leave room for supplemental state legislation, while at the same time, prohibiting supplemental municipal legislation. This premise is both contrary to the Supreme Court’s ruling in Mortier and contrary to reason. In Mortier, the Supreme Court considered whether the Federal Insecticide, Fungicide and Rodenticide Act (“FIFRA”) preempted a local ordinance adopted by the city of Casey, Wisconsin. Mortier, 501 U.S. at 602, 111 S.Ct. 2476. The ordinance at issue required a permit “for the application of any pesticide to public lands, to private lands subject to public use, or for the aerial application of any pesticide to private lands.” Id. When Casey prohibited Ralph Mortier from the aerial spraying of pesticides on certain property based on the local ordinance, Mortier filed suit alleging, inter alia, that the local pesticide ordinance was preempted by FIFRA. Id. at 603, 111 S.Ct. 2476. The Supreme Court held that FIFRA does not preempt the Casey pesticide ordinance. In so holding, the Court began its analysis by noting that FIFRA expressly authorizes “Statefs]” to regulate pesticides, but makes no reference in the savings clause to political subdivisions of states. Id. at 606-07, 111 S.Ct. 2476. The Court went on to find, however, that the term “State” is broad enough to encompass political subdivisions, and that the fact that FIFRA is silent with respect to the power of local governments “cannot suffice to establish a clear and manifest purpose to preempt local authority.” Id. at 607, 111 S.Ct. 2476 (internal quotation omitted). As the Court explained: The exclusion of political subdivisions cannot be inferred from the express authorization to the “Statefs]” because political subdivisions are components of the very entity the statute empowers. Indeed, the more plausible reading of FI-FRA’s authorization to the States leaves the allocation of regulatory authority to the “absolute discretion” of the States themselves, including the option of leaving local regulation of pesticides in the hands of local authorities. Id. at 608, 111 S.Ct. 2476. We find that Mortier’s reasoning regarding FIFRA is equally applicable to CERCLA. Like FIFRA, CERCLA anticipates that states will enact supplemental remedial environmental legislation. Accord Akzo Coatings, 949 F.2d at 1454 (“CERCLA sets only a floor, not a ceiling, for environmental protection. Those state laws which establish more stringent environmental standards are not preempted by CERCLA.”). Moreover, like FIFRA, the CERCLA savings clauses refer only to “State[s],” while CERCLA specifically refers to both states and political subdivisions in other provisions. Compare 42 U.S.C. § 9614(a) (referring only to “State[s]”)> with 42 U.S.C. § 9606(a) (referring to “a State or local government”). CERCLA is also like FIFRA in that CERCLA does not preclude states from re-delegating their authority to political subdivisions. Fireman’s Fund, 41 F.Supp.2d at 1110. Indeed, that is precisely what occurred in this case. Lodi specifically adopted MERLO pursuant to a Cooperative Agreement entered into by Lodi and DTSC, the state agency charged with interpreting and enforcing California’s hazardous waste laws. Lodi’s exercise of its municipal authority to provide for local nuisance abatement through the adoption of MERLO has therefore been sanctioned by the State of California. Moreover, in California, municipal ordinances are state law and may be prosecuted in the name of the “people of the State of California.” Cal. Gov’t Code § 36900(a) (West 2001) (“Violations of a city ordinance is a misdemeanor unless by 'ordinance it is made an infraction. Such a violation may be prosecuted by city authorities in the name of the people of the State of California, or redressed by civil action.”). In addition, the California Constitution provides Lodi and other cities with broad municipal authority to address local environmental nuisances, Cal. Const., Art. XI, § 7, and the California Legislature has adopted numerous laws authorizing political subdivisions to adopt ordinances for the protection of the environment. See, e.g., Cal. Gov’t Code § 38771 (West 2001) (providing cities with the authority to determine what constitutes a public nuisance); Cal. Gov’t Code § 38773 (West 2001) (granting cities the authority to provide for the abatement of public nuisances). Included among these state laws is HSAA, which the Insurers acknowledge is not preempted by CERCLA. HSAA’s savings clause provides that with certain exceptions not applicable here, HSAA does not “affect or modify in any way the obligations or liabilities or any person under any other provision of state or federal laws.” Cal. H & S Code § 25366 (emphasis added). Significantly, the phrase “state law” is defined in § 25326 to include municipalities. See Cal. H & S Code § 25326 (“A ‘release authorized or permitted pursuant to state law’ means any release into the environment which is authorized by statute; ordinance, regulation, or rule of any state, regional, or local agency or government ...” ). HSAA § 25351.2 also permits a “city or county” to “initiate a removal or remedial” HSAA enforcement action. Cal. H & S Code §■ 25351.2. Thus, HSAA itself contemplates the ability of cities to adopt parallel municipal environmental ordinances and participate in the process of hazardous waste remediation. Under these circumstances, we agree with the district court that the term “State” as used in CERCLA is broad enough to include political subdivisions such as Lodi. In the absence of a strong indication to the contrary, we fall back on the presumption that Congress did not intend CERCLA to “den[y] local communities throughout the Nation significant powers of self-protection.” Mortier, 501 U.S. at 621, 111 S.Ct. 2476 (Scalia, J., concurring); see also Western Oil and Gas Assoc. v. Monterey Bay Unified Air Pollution Control Dist., 49 Cal.3d 408, 261 Cal.Rptr. 384 393-94, 777 P.2d 157 (1989) (“In view of the long tradition of local regulation and the legislatively imposed duty [on local governments] to preserve and protect the public health, preemption may not be lightly found.”). Although the Insurers urge us to hold that CERCLA preempts MERLO but not HSAA, they fail to explain why Congress would preempt local environmental legislation without exclusively occupying the field and obtaining whatever uniformity benefits might flow from preemption. On the contrary, we find that the more plausible reading of CERCLA is that the statute leaves room for the creation of an arsenal of remedial environmental regulations through a comprehensive “partnership between federal, state and local governments.” Mortier, 501 U.S. at 615, 111 S.Ct. 2476 (emphasis in original), (discussing FIFRA). Accordingly, we hold that CERCLA permits both states and their political subdivisions to enact hazardous waste regulations and “pursue additional remedies at [their] own expense, as long as those remedies do not conflict or interfere with,” Akzo Coatings, 949 F.2d at 1454, “the accomplishment and execution of [CERCLA’s] full purpose and objective....” Industrial Truck Ass’n, 125 F.3d at 1309. c. Conflict Preemption The Insurers next assert that CERCLA and HSAA preempt seven specific portions of MERLO under the doctrine of conflict preemption. As discussed above, we will find federal conflict preemption where “compliance with both the federal and state regulations is a physical impossibility,” or when the state law stands as “an obstacle to the accomplishment and execution of the full purposes and objectives of Congress.” California Fed. Sav. and Loan Ass’n v. Guerra, 479 U.S. 272, 281, 107 S.Ct. 683, 93 L.Ed.2d 613 (1987). Similarly, we will find conflict preemption under California law when a local ordinance prohibits conduct that is expressly authorized by state statute or authorizes conduct that is expressly prohibited by state general law. Sports Comm. Dist. v. County of San Bernardino, 113 Cal.App.3d 155, 159, 169 Cal.Rptr. 652 (1980). The Insurers challenge the following seven sections of MERLO as preempted: (1) the MERLO section permitting Lodi to be compensated for damage to its natural resources; (2) the MERLO sections addressing the cleanup standard set forth in the NCP; (3) the MERLO section authorizing Lodi to gather certain information from PRPs and their insurers; (4) the MERLO sections defining “abatement action costs” to permit Lodi to recover attorney’s fees and interest; (5) the MERLO section permitting Lodi to bring direct actions against insurers of PRPs; (6) MER-LO’s general liability scheme, including the sections of MERLO that provide for the joint and several liability of PRPs, and the sections setting forth the contribution rights of PRPs; and (7) MERLO’s burden of proof for establishing a defense to liability. (1) Natural Resource Damages MERLO § 8.24.040(A)(9)(c) states that PRPs shall be liable for “[d]amages for injury to, déstruction of, or loss of natural resources, including the reasonable costs of assessing such injury, destruction, or loss resulting from the environmental nuisance.” MERLO § 8.24.040(A)(9)(c) (emphasis added). The Insurers contend that' this provision of MERLO is preempted by state and federal law because “under CERCLA and ... HSAA, a State must designate a city as its authorized representative before a city may seek natural resource damages.” According to the Insurers, because Lodi has not been designated the “authorized representative” of the State of California, it cannot recover for damages to its natural resources. We disagree with this assertion. “CERCLA includes mechanisms for restoring natural resources that have been destroyed as a result of hazardous waste dumping and discharge.” Michael J. Witt-ke, Comment, Municipal Recovery of Natural Resource Damages Under CERCLA, 23 B.C. Envtl. Aff. L.Rev. 921, 925 (1996). One such mechanism is CERCLA § 107(f)(1), which provides states, federal agencies, and Indian Tribes with a federal cause of action to sue for damages to natural resources that they hold in trust for the public. See 42 U.S.C. §§ 9607(a)(4)(C), (f)(1). “Natural resource damages include injury or loss of land, fish, wildlife, biota, air, water, ground water, drinking water supplies, and other resources belonging to, managed by, or otherwise controlled by the United States or state or local governments.” State of Idaho v. Hanna Mining Co., 882 F.2d 392, 394 (9th Cir.1989) (citing 42 U.S.C. §§ 9601(6), 9601(16)). Specifically, CERCLA § 107(f)(1) states that: In the case of an injury to, destruction of, or loss of natural resources under [107(1)(4)(C)] liability shall be to the United States Government and to any State for natural resources within the State or belonging to, managed by, controlled by or appertaining to such State.... The President, or the authorized representative of any State, shall act on behalf of the public as trustee of such natural resources to recover for such damages. 42 U.S.C. § 9607(f)(1). CERCLA thus allows “the President of the United States or the Governor of a State to designate officials to act on behalf of the public as trustees for natural resources.” City of Toledo v. Beazer Materials and Servs., Inc., 833 F.Supp. 646, 650 (N.D.Ohio 1993). Similarly, under HSAA, the Governor of California or an “authorized representative” of the State may recover natural resources damages. Cal. H & S Code § 25352(c). It is unnecessary for us to determine whether a municipality may recover under CERCLA for damage to its natural resources in the absence of being designated the authorized representative of a state. Lodi does not asser