Full opinion text
TABLE OF CONTENTS T¡ Background . I. A. Statutory Background. B. The Natural Resource Damage Assessment Regulations. STANDARD OP REVIEW. II. The “Lesser-Of” Rule. III. A. The Contours of “the Precise Question at Issue”. B. Text and Structure of CERCLA. 1. Section 107(f)(1) and the Measure of Damages. a. Limitation on Uses of Recovered Damages. b. The “Shall Not Be Limited By” Language. 2. Interior’s Reading of CERCLA §§ 301 and 107 . a. The “Take Into Consideration” Language. b. The Assessment Costs Language. c. The “Shall Not Be Limited By” Language. 3. Superfund Provisions . 4. Settlement Provision. 5. Double Recovery Provision. 6. CERCLA and the Clean Water Act. C. Legislative History of CERCLA. 1. The Enactment of CERCLA in 1980 . 2. The Enactment of SARA in 1986. 3. Congress’ Rejection of the Premises Underlying the “Lesser-Of” Rule. a. CERCLA and the Common-Law Measure of Damages_ b. CERCLA and Economic Efficiency.-. 4. Acquiescence-by-Reenactment Argument. D. Conclusion . The Public Ownership Rule. IV. A. The Statute. 1. Statutory Language. 2. Legislative History. B. The Regulations and Accompanying Commentary. The “Committed Use” Requirement. y. The Hierarchy of Assessment Methods. VI. The Ten Percent Discount Rate. VII. The Allegedly Preferential Treatment of PRPs. VIII. A. Delegation of the Assessment Process to PRPs. 1. Delegability of Assessment Tasks Generally. 2. Specific Aspects of the Delegation Rule. B. Public Notice and Comment. Limitation on Recovery of Assessment Costs. The The Acceptance Criteria. A. The Regulations.. B. Analysis . 1. CERCLA and the Common-Law Causation Standard. ''ÑT 2. The Reasonableness Test. ■'ÑP 3. Noncompensability of General Studies . ’'ÑP Audit Requirements. ^ÑP X Page XII. Punitive Damages . 474 XIII. Contingent Valuation. 474 A. The Regulatory Background . 474 B. Consistency With CERCLA. 476 C. Presumption of Validity of CV Assessments.478 XIV. Conclusion. 481 WALD, Chief Judge, and SPOTTSWOOD W. ROBINSON III and MIKVA, Circuit Judges: Petitioners are 10 states, three environmental organizations (“State and Environmental Petitioners”), a chemical industry trade association, a manufacturing company and a utility company (“Industry Petitioners”), who seek review of regulations promulgated by the Department of the Interior (“DOI” or “Interior”) pursuant to § 301(c)(l)-(3) of the Comprehensive Environmental.Response, Compensation and Liability Act of 1980 (“CERCLA” or the “Act”), as amended, 42 U.S.C. § 9651(c). The regulations govern the recovery of money damages from persons responsible for spills and leaks of oil and hazardous substances, to compensate for injuries such releases inflict on natural resources. Damages may be recovered by state and in some cases the federal governments, as trustees for those natural resources. Petitioners challenge many aspects of those regulations. State and Environmental Petitioners raise ten issues, all of which essentially focus on the regulations’ alleged undervaluation of the damages recoverable from parties responsible for hazardous materials spills that despoil natural resources. Industry Petitioners attack the regulations from a different vantage point, claiming they will permit or encourage overstated damages. In addition, three public interest organizations (“Environmental Intervenors”) defend the regulations from the attacks of Industry Petitioners, and a collection of corporations and industry groups (“Industry Intervenors”) defend the regulations from the attacks of State and Environmental Petitioners. We hold that the regulation limiting damages recoverable by government trustees for harmed natural resources to “the lesser of” (a) the cost of restoring or replacing the equivalent of an injured resource, or (b) the lost use value of the resource is directly contrary to the clearly expressed intent of Congress and is therefore invalid. We also hold that the regulation prescribing a hierarchy of methodologies by which the lost-use value of natural resources may be measured, which focuses exclusively on the market values for such resources when market values are available, is not a reasonable interpretation of the statute. We remand the record to DOI for a clarification of its interpretation of its own regulations concerning the applicability of the CERCLA natural resource damage provisions to privately owned land that is managed or controlled by a federal, state or local government. We reject all other challenges to Interior’s regulations. I. BACKGROUND A. Statutory Background CERCLA, popularly known as Superfund, was enacted in 1980. Pub.L. ’ No. 96-510, 94 Stat. 2767 (1980). Congress amended it in 1986, in the Superfund Amendments and Reauthorization Act (“SARA”), Pub.L. No. 99-499, 100 Stat. 1613 (1986). Unless otherwise specified, references to CERCLA in this opinion refer to the statute as amended. CERCLA furnishes the executive branch with the authority to respond to actual and threatened releases of “hazardous substance[s]” and “pollutant[s] or contaminant[s].” § 104(a)(1), 42 U.S.C. § 9604(a)(1). Response actions may include both “removal” (i.e., cleanup of the spilled substance) and “remedial action” (e.g., dredging, repair of leaking containers, collection of rainfall runoff, relocation of displaced residents). § 101(23)-(25), 42 U.S.C. § 9601(23)-(25). CERCLA established the Superfund as a source of expeditious payment for response actions, although ultimately the liability for response costs is placed on specified classes of responsible parties: past and present owners and operators of vessels and facilities; waste generators or other persons who arranged for disposal, treatment or transport of hazardous substances; and transporters of hazardous substances. §§ 111(a)(1), 107(a), 42 U.S.C. §§ 9611(a)(1), 9607(a). Responsible parties may be required to pay the response costs or, in some cases, to perform the response actions themselves. §§ 106(a), 107(a)(A)-(B), 42 U.S.C. §§ 9606(a), 9607(a)(A)-(B). The relevant provisions of CERCLA in this case, however, go beyond the mere removal or remedying of spills. CERCLA provides that responsible parties may be held liable for “damages for injury to, destruction of, or loss of natural resources, including the reasonable costs of assessing such injury, destruction, or loss resulting from such a release.” § 107(a)(C), 42 U.S. C. § 9607(a)(C). Liability is 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.” § 107(f)(1), 42 U.S.C. § 9607(f)(1). The Act provides for the designation of federal and state “trustees” who are authorized to assess natural resource damages and press claims for the recovery of such damages, both under CERCLA and under § 311 of the Federal Water Pollution Control Act (commonly referred to as the “Clean Water Act”), 33 U.S.C. § 1321. CERCLA § 107(f)(2), 42 U.S.C. § 9607(f)(2). Congress conferred on the President (who in turn delegated to Interior) the responsibility for promulgating regulations governing the assessment of damages for natural resource injuries resulting from releases of hazardous substances or oil, for the purposes of CERCLA and the Clean Water Act’s § 311(f)(4)-(5) oil and hazardous substance natural resource damages provisions, 33 U.S.C. § 1321(f)(4) — (5). These regulations originally were required to be in place by December 1982. § 301(c), 42 U.S.C. § 9651(c). CERCLA prescribed the creation of two types of procedures for conducting natural resources damages assessments. The regulations were to specify (a) “standard procedures for simplified assessments requiring minimal field observation” (the “Type A” rules), and (b) “alternative protocols for conducting assessments in individual cases” (the “Type B” rules). § 301(c)(2), 42 U.S.C. § 9651(c)(2). Both the Type A and the Type B rules were to “identify the best available procedures to determine such damages.” Id. The regulations must be reviewed and revised as appropriate every two years. § 301(c)(3), 42 U.S.C. § 9651(c)(3). Under the Act, a trustee seeking damages is not required to resort to the Type A or Type B procedures, but CERCLA as amended provides that any assessment performed in accordance with the prescribed procedure is entitled to a rebuttable presumption of accuracy in a proceeding to recover damages from a responsible party. § 107(f)(2)(C), 42 U.S.C. § 9607(f)(2)(C). In August 1986, Interior published a final rule containing the Type B regulations for natural resource damage assessments, the subject of this lawsuit. Shortly thereafter, in October 1986, Congress adopted SARA, amending the natural resources damages provisions of CERCLA in several respects. For example, SARA provided that assessments performed by state as well as federal trustees were entitled to a rebuttable presumption, it provided for the recovery of prejudgment interest on damage awards, and it proscribed “double recovery” for natural resources damages. §§ 107(f)(2)(C), 107(a), 107(f)(1), 42 U.S.C. §§ 9607(f)(2)(C), 9607(a), 9607(f)(1). SARA also amended § 301(c) to require Interior to adopt any necessary conforming amendments to its natural resource damage assessment regulations within six months of the effective date of the amendments, “[n]otwithstanding the failure of the President to promulgate the regulations required under this subsection on the required [December 1982] date.” § 301(c)(1), 42 U.S.C. § 9651(c)(1). B. The Natural Resource Damage Assessment Regulations Interior’s response to its assigned task of promulgating regulations for assessing natural resource damages was, to put it charitably, relaxed. In January 1983, after the original statutory deadline had come and gone, Interior issued an advance notice of proposed rulemaking soliciting comments from the public on how to approach the development of the regulations. 48 Fed.Reg. 1,084 (1983). A second advance notice of proposed rulemaking seven months later summarized the comments received in response to the first notice. 48 Fed.Reg. 34,768 (1983). More than a year later, in January 1985, Interior published a notice inviting more public comments and suggesting meetings with interested members of the public. 50 Fed.Reg. 1,550 (1985). In December 1985, five years after the enactment of CERCLA and three years after the statutory deadline, Interior published a proposed rule setting out (a) regulations concerning the assessment process generally (applicable to both Type A and Type B assessments) and (b) Type B rules in particular. 50 Fed.Reg. 52,126 (1985). A comment period originally set at 45 days was later extended an additional 15 days. 50 Fed.Reg. at 52,126; 51 Fed.Reg. 4,397 (1986). Ultimately, on August 1, 1986, Interior published a final rule containing general natural resource damage assessment regulations as well as the Type B rules challenged in the present case. 51 Fed.Reg. 27,674 (1986) (codified at 43 C.F.R. §§ 11.-10-11.93 (1987)). The assessment process established by the Type B regulations has four phases. In the “preassessment phase,” a trustee that has become aware of a release of hazardous substances or oil makes an initial determination whether natural resources may have been affected. If further action is deemed warranted, the trustee enters the “assessment plan phase,” in which an assessment strategy .is mapped out. Next comes the “assessment phase,” in which the trustee establishes whether there was in fact an injury to natural resources, quantifies the extent of the injury, and ascertains the appropriate dollar-amount of damages caused by the release. Finally, in the “post-assessment phase,” the trustee assembles a report documenting the assessment process and presents the responsible party with a demand for payment of damages. See 51 Fed.Reg. at 27,726-27. The August 1986 regulations were promptly challenged by state governments, environmental groups, industrial corporations and an industry group. Shortly after the issuance of the August 1986 regulations, Congress amended CERCLA by enacting SARA. As noted above, SARA gave Interior six months in which to conform its natural resource damage assessment rules to the amended statute. In response to SARA, Interior issued revised rules (following notice and comment) in February 1988. 53 Fed.Reg. 5,166 (1988). A state government and an environmental group filed additional challenges to these revised rules, which this court consolidated with the original case. Interior’s formulation of Type A rules (governing simplified damage assessments) was handled in a separate rulemaking proceeding. Following notice and comment, a set of Type A rules was issued as a final rule in March 1987. 52 Fed.Reg. 9,042 (1987). The Type A rules are the subject of a separate petition for review, which was briefed and argued simultaneously with the present case and is decided today in State of Colorado v. Department of the Interior, 880 F.2d 481 (D.C.Cir.1989). II. Standard of Review In reviewing an agency’s interpretation of a statute, we first determine “whether Congress has directly spoken to the precise question at issue.” Chevron U.S.A., Inc. v. Natural Resources Defense Council, Inc., 467 U.S. 837, 842, 104 S.Ct. 2778, 2781, 81 L.Ed.2d 694 (1984). If so, then both Interior and this court “must give effect to the unambiguously expressed intent of Congress.” Chevron, 467 U.S. at 842-43, 104 S.Ct. at 2781; accord NLRB v. United Food & Comm’l Workers Union Local 23, 484 U.S. 112, 108 S.Ct. 413, 421, 98 L.Ed.2d 429 (1987). This is “Step One” of Chevron analysis. Whether Congress has made its intent clear and unambiguous does not depend on whether a particular phrase of the statutory text standing all alone resolves the matter. Rather, the court must look beyond “the particular statutory language at issue” and examine “the language and design of the statute as a whole.” K Mart Corp. v. Cartier, Inc., 486 U.S. 281, 108 S.Ct. 1811, 1817, 100 L.Ed.2d 313 (1988). “It is a fundamental canon of statutory construction that the words of a statute must be read in their context and with a view to their place in the overall statutory scheme.” Davis v. Michigan Dept. of Treasury, — U.S. -, 109 S.Ct. 1500, 1504, 103 L.Ed.2d 891 (1989). Moreover, as the Supreme Court indicated in Chevron and has reiterated since then, the reviewing court must “employ[ ] traditional tools of statutory construction” — including, when appropriate, legislative history — to determine whether Congress “had an intention on the precise question at issue.” Chevron, 467 U.S. at 843 n. 9, 104 S.Ct. at 2781 n. 9; accord United Food & Comm’l Workers Union, 108 S.Ct. at 421; INS v. Cardoza-Fonseca, 480 U.S. 421, 446-48, 107 S.Ct. 1207, 1220-22, 94 L.Ed.2d 434 (1987). If the court, having studied the statutory text, structure and history, is left with the unmistakable conclusion that Congress had an intention on the precise question at issue, “that intention is the law and must be given effect.” Chevron, 467 U.S. at 843 n. 9, 104 S.Ct. at 2781 n. 9. If, on the other hand, the statute is ambiguous or is silent on a particular issue, this court must assume that Congress implicitly delegated to the agency the power to make policy choices that “ ‘represent[ ] a reasonable accommodation of conflicting policies that were committed to the agency’s care by the statute.’ ” Chevron, 467 U.S. at 844-45, 104 S.Ct. at 2783, quoting United States v. Shimer, 367 U.S. 374, 383, 81 S.Ct. 1554, 1560, 6 L.Ed.2d 908 (1961). In that event, the court must defer to the agency’s interpretation of the statute so long as it is reasonable and consistent with the statutory purpose. Id. This is “Step Two” of Chevron analysis. We first take up the ten issues raised by State and Environmental Petitioners, followed by the one issue raised by Industry Petitioners. III. The “Lesser-Of” Rule The most significant issue in this case concerns the validity of the regulation providing that damages for despoilment of natural resources shall be “the lesser of: restoration or replacement costs; or diminution of use values.” 43 C.F.R. § 11.35(b)(2) (1987) (emphasis added). State and Environmental Petitioners challenge Interior’s “lesser of” rule, insisting that CERCLA requires damages to be at least sufficient to pay the cost in every case of restoring, replacing or acquiring the equivalent of the damaged resource (hereinafter referred to shorthandedly as “restoration”). Because in some — probably a majority of — eases lost-use-value will be lower than the cost of restoration, Interior’s rule will result in damages award too small to pay for the costs or restoration. Petitioners point to a section of CERCLA providing that recovered damages must be spent only on restoration as evidence that Congress intended restoration cost-based damages to be the norm. As further proof of such a norm, the same section goes on to state that the measure of damages “shall not be limited by” the sums which can be used for restoration. Petitioners maintain that the “shall not be limited by” language clearly establishes restoration costs as a “floor” measure of damages. Petitioners also rely on the legislative history of CERCLA and of SARA, claiming that it reinforces the sense of the text and documents Congress’ primary emphasis on restoration of natural resources. In particular, they point to a House report on SARA, insisting that it, together with the other statutory indicators, proves conclusively that Congress intended restoration costs to be a minimum measure of damages in natural resource eases. Interior defends its rule by arguing that CERCLA does not prescribe any floor for damages but instead leaves to Interior the decision of what the measure of damages will be. DOI acknowledges that all recovered damages must be spent on restoration but argues that the amount recovered from the responsible parties need not be sufficient to complete the job. DOI suggests two alternative meanings of the “shall not be limited by” phrase that do not construe it as a damages floor. Finally, DOI argues that the legislative history, like the statutory text, is ambiguous and that Interior’s rule for measuring damages is a reasonable one. Although our resolution of the dispute submerges us in the minutiae of CERCLA text and legislative materials, we initially stress the enormous practical significance of the “lesser of” rule. A hypothetical example will illustrate the point: imagine a hazardous substance spill that kills a rookery of fur seals and destroys a habitat for seabirds at a sealife reserve. The lost use value of the seals and seabird habitat would be measured by the market value of the fur seals’ pelts (which would be approximately $15 each) plus the selling price per acre of land comparable in value to that on which the spoiled bird habitat was located. Even if, as likely, that use value turns out to be far less than the cost of restoring the rookery and seabird habitat, it would nonetheless be the only measure of damages eligible for the presumption of recov-erability under the Interior rule. After examining the language and purpose of CERCLA, as well as its legislative history, we conclude that Interior’s “lesser of” rule is directly contrary to the expressed intent of Congress. A. The Contours of “the Precise Question at Issue” Commencing our Chevron analysis, we must first decide exactly what “the precise question at issue” is in the present case. Chevron, 467 U.S. at 842, 104 S.Ct. at 2781. Much depends on accurately identifying that issue so as to decide whether Congress has “directly spoken” on it; if so, under Chevron’s “Step One” we must give effect to that unambiguously expressed intent. If not, we proceed instead to “Step Two” and determine whether Interior’s construction of CERCLA is reasonable and consistent with the statutory purpose. State and Environmental Petitioners posit that the precise question at issue in this case is what measure of damages must be applied in natural resource damage actions. They argue that Congress did address the precise question at issue by deciding that damages must at a minimum encompass the full cost of restoration in every case. See Pet. Br. 18-22. Therefore, petitioners say, this court must strike down the “lesser of” rule on Chevron Step One grounds. Interior also assumes that the precise question at issue here is what measure of damages must be applied in natural resource damage actions. Interior’s position, however, is that Congress did not definitively address that question. See Resp. Br. 25-27; 51 Fed.Reg. 27,705. To support this view, Interior points out that Congress did not choose a particular measure of damages, opting instead to authorize the President to draft regulations governing the assessment of damages. § 301(c)(2), 42 U.S.C. § 9651(c)(2) (regulations shall “identify the best available procedures to determine ... damages” and shall “take into consideration” certain listed factors, among others). Since Congress delegated the matter to the President (who turned it over to DOI), DOI argues that this case is governed by Chevron Step Two and that its “lesser of” rule must be upheld if not unreasonable or inconsistent with the statutory purpose. We find both parties’ arguments flawed in one important respect. Both fail to properly describe the “precise question at issue” in the “lesser-of” rule. That question is not what measure of damages should apply in any or all cases which are brought under the Act. As to that larger question, Interior is obviously correct in asserting that Congress delegated to it a considerable measure of discretion in formulating a standard. See § 301(c)(2), 42 U.S.C. § 9651(c)(2). The precise question here is a far more discrete one: whether DOI is entitled to treat use value and restoration cost as having equal presumptive legitimacy as a measure of damages. Interior’s “lesser of” rule operates on the premise that, as the cost of a restoration project goes up relative to the value of the injured resource,- at some point it becomes wasteful to require responsible parties to pay the full cost of restoration. See 51 Fed.Reg. at 27,704-05; 50 Fed.Reg. at 52,141. The logic behind the rule is the same logic that prevents an individual from paying $8,000 to repair a collision-damaged car that was worth only $5,000 before the collision. Just as a prudent individual would sell the damaged car for scrap and then spend $5,000 on a used car in similar condition, DOI’s rule requires a polluter to pay a sum equal to the diminution in the use value of a resource whenever that sum is less than restoration cost. What is significant about Interior’s rule is the point at which it deems restoration “inefficient.” Interior chose to draw the line not at the point where restoration becomes practically impossible, nor at the point where the cost of restoration becomes grossly disproportionate to the use value of the resource, but rather at the point where restoration cost exceeds — by any amount, however small — the use value of the resource. Thus, while we agree with DOI that CERC-LA permits it to establish a rule exempting responsible parties in some cases from having to pay the full cost of restoration of natural resources, we also agree with Petitioners that it does not permit Interior to draw the line on an automatic “which costs less” basis. Interior’s “lesser of” rule squarely rejects the concept of any clearly expressed congressional preference for recovering the full cost of restoration from responsible parties. The challenged regulation treats the two alternative measures of damages, restoration cost and use value, as though the choice between them were a matter of complete indifference from the statutory point of view: thus, in any given case, the rule makes damages turn solely on whichever standard is less expensive. (An analogy would be a government procurement rule that dictated the purchase of the lowest-priced goods, regardless of whether they were domestically made or imported.) If Congress, however, in enacting CERC-LA, clearly expressed an intention that DOI’s damage measurement rules incorporate a distinct preference for restoration cost over use value, then the “lesser of” rule is inconsistent with that intent. Congress’ expressed preference would mean that restoration cost must normally be preferred over use value despite use value being the “lesser” figure, except in unusual situations where the disadvantages or expenses were extreme. (Returning to our analogy, the lowest-price procurement rule would be invalid under Chevron Step One if it were promulgated under a statute clearly mandating a preference for domestic goods.). Based on the discussion that-follows, we conclude that CERCLA una,yá-biguously mandates a distinct preference for using restoration cost as the measure of damages, and so precludes a “lesser of” rule which totally ignores that preference. B. Text and Structure of CERCLA CERCLA provides that parties responsible for hazardous substance releases “shall be liable for ... damages for injury to, destruction of, or loss of natural resources, including the reasonable costs of assessing such injury, destruction, or loss resulting from such a release.” § 107(a)(C), 42 U.S.C. § 9607(a)(C). The Regulations promulgated pursuant to § 107(a)(0) are to identify procedures for measuring damages that “shall take into consideration factors including, but not limited to, replacement value, use value, and ability of the ecosystem or resource to recover.” § 801(c)(2), 42 U.S.C. § 9651(c)(2). While CERCLA thus empowers DOI to formulate a measure of damages, several other provisions of the Act make it clear that replacement cost and use value are not to be accorded equal presumptive legitimacy in the process. 1. Section 107(f)(1) and the Measure of Damages The strongest linguistic evidence of Congress’ intent to establish a distinct preference for restoration costs as the measure of damages is contained in § 107(f)(1) of CERCLA. That section states that natural resource damages recovered by a government trustee are “for use only to restore, replace, or acquire the equivalent of such natural resources.” 42 U.S.C. § 9607(f)(1). It goes on to state: “The measure of damages in any action under [§ 107(a)(C) ] shall not be limited by the sums which can be used to restore or replace such resources.” Id. a. Limitation on Uses of Recovered Damages By mandating the use of all damages to restore the injured resources, Congress underscored in § 107(f)(1) its paramount restorative purpose for imposing damages at all. It would be odd indeed for a Congress so insistent that all damages be spent on restoration to allow a “lesser” measure of damages than the cost of restoration in the majority of cases. Only two possible inferences about congressional intent could explain the anomaly: Either Congress intended trustees to commence restoration projects only to abandon them for lack of funds, or Congress expected taxpayers to pick up the rest of the tab. The first theory is contrary to Congress’ intent to effect a “make-whole” remedy of complete restoration, and the second is contrary to a basic purpose of the CERCLA natural resource damage provisions — that polluters bear the costs of their polluting activities. It is far more logical to presume that Congress intended responsible parties to be liable for damages in an amount sufficient to accomplish its restorative aims. Interi- or’s rule, on the other hand, assumes that Congress purposely formulated a statutory scheme that would doom to failure its goals of restoration in a majority of cases. In this connection, it should be noted that Interior makes no claim that a “use value” measure will provide enough money to pay for any of the three uses to which all damages must be assigned: restoration, replacement or acquisition of an equivalent resource. Nor could Interior make such a claim, because its “lesser of” rule not only calculates use value quite differently from restoration or replacement cost but it also fails to link measurement of use value in any way to the cost of acquiring an equivalent resource. For example, Interior could not possibly maintain that recovering $15 per pelt for the fur seals killed by a hazardous substance release would enable the purchase of an “equivalent” number of fur seals. b. The “Shall Not Be Limited By” Language The same section of CERCLA that mandates the expenditures of all damages on restoration (again a shorthand reference to all three listed uses of damages) provides that the measure of damages “shall not be limited by” restoration costs. § 107(f)(1), 42 U.S.C. § 9607(f)(1). This provision obviously reflects Congress’ apparent concern that its restorative purpose for imposing damages not be construed as making restoration cost a damages ceiling. But the explicit command that damages “shall not be limited by” restoration costs also carries in it an implicit assumption that restoration cost will serve as the basic measure of damages in many if not most CERCLA cases. It would be markedly inconsistent with the restorative thrust of the whole section to limit restoration-based damages, as Interior’s rule does, to a minuscule number of cases where restoration is cheaper than paying for lost use. 2. Interior’s Reading of CERCLA §§ 301 and 107 In the face of § 107’s clear preference for restoration as the basic measure of natural resource damages, DOI and Industry Intervenors advance “ambiguities” in the language of §§ 301 and 107, asserting that those ambiguities are sufficient to permit Interior to promulgate the “lesser of” rule under Chevron Step Two. a. The “Take Into Consideration” Language First, Interior argues that the “take into consideration” language of § 301(c)(2) delegates to Interior the decision of whether and how restoration cost should be taken into consideration. Resp. Br. 25-27; 51 Fed.Reg. 27,705. We have acknowledged that CERCLA does confer on DOI discretion in fashioning the measure of damages; indeed, if § 301(c)(2) were the only instruction Congress had given, DOI’s argument would be a strong one. But the reality is that Interior’s discretion is cabined by Congress’ determination, as evidenced by the statutory text discussed above, that the measure of damages reflect a preference for restoration cost, at least where restoration is feasible and can be performed at a cost not grossly disproportionate to the use value of the resource. Thus, while DOI is correct in pointing to the “take into consideration” language as hinting at a measure of latitude on the part of DOI, the degree of latitude conferred by Congress is not infinite. b. The Assessment Costs Language Industry Intervenors argue that the reference in § 107(a)(C) to including assessment costs in damages awards indicates, by the principle of expressio unius est exclu-sio alterius, that Congress intended only the one narrow departure from common-law damage measurement standards. But this crabbed reading ignores the existence of § 301(c)(2), which states that the factors to be taken into account by the regulations “includ[e] but [are] not limited to” replacement cost and use value. Under the common law, the Industry Intervenors would have us believe, there are no other factors to consider. In light of § 301(c)(2), the expressio unius argument, at best a canon for construing statutes in the absence of more definite guidance within the four corners of the act itself, loses force. We do not think Congress’ mere mention of assessment costs in § 107(a)(0) implicitly excludes all other non-common-law components of damages. c. The “Shall Not Be Limited By” Language Interior and Industry Intervenors propose several alternative readings of the “shall not be limited by” language of § 107(f)(1) in an effort to show that Congress did not unambiguously express a preference for restoration cost as the basic measure of CERCLA natural resource damages. None of their various constructions is plausible, however. They first contend that the phrase “shall not be limited by” dictates not the measure of damages but the uses to which damages must be put. Industry Intervenors argue that Congress’ “primary purpose” in this portion of § 107(f) was “to describe the appropriate uses of the natural resource damages once they are recovered, while making sure that section 107(f) did not contradict the scope of recovery set forth in section 107(a)(C).” Ind. Int. Br. 16 (emphasis in original). This is a difficult argument to understand, let alone accept. First, the notion that a sentence beginning with the words, “The measure of damages ... shall ...” refers only to the uses of damages rather than the proper measure of damages is counterintuitive, especially when the sentence immediately preceding it expressly refers to the uses of damages. Second, we fail to see why Congress need be concerned that § 107(f)(1) would “contradict the scope of recovery set forth in” § 107(a)(C). The latter section simply imposes liability for “damages” for injury or loss to natural resources (including assessment costs). Any conflict with subsection (f)(1) is of Industry’s own making; it arises only if, as Industry does, one reads a common-law limitation into the word “damages.” See supra note 14. The whole argument strikes us as circular. Indeed, the fact that subsection (f)(1) itself explicitly cross-references subsection (a)(C) as the source of liability indicates Congress’ conscious design to read the two subsections as compatible and complementary: liability for “damages” is established in subsection (a)(C), while subsection (f)(1) orders DOI not to place a restoration-cost ceiling on the “measure of damages.” Industry Inter-venors’ caution that subsection (f)(1) should not be read “to supplant the measure of damages established in” subsection (a)(C), Ind. Int. Br. 17, is superfluous: subsection (a)(C) does not purport to set a measure of damages, while subsection (f)(1) contains an explicit command regarding “[t]he measure of damages in any action under” subsection (a)(C). Alternatively, DOI and Industry Inter-venors propose two readings of the phrase “shall not be limited by,” both of which negate restoration costs as the preferred measure of damages. First, they suggest that the phrase means that damages need not be measured by restoration costs at all; a different measure, i.e., lost use value, is perfectly acceptable under appropriate circumstances. See 51 Fed.Reg. at 27,704-05. This reading, however, seems strained and does not accord with the usual meaning of the phrase “shall not be limited by.” Its implausibility is even more obvious from context. The relevant passage reads as follows: Sums recovered by a State as trustee under this subsection shall be available for use only to restore, replace, or acquire the equivalent of such natural resources by the State. The measure of damages in any action under subpara-graph (C) of subsection (a) of this section shall not be limited by the sums which can be used to restore or replace such resources. § 107(f)(1), 42 U.S.C. § 9607(f)(1). Plainly, the statute lists three legitimate uses of the money (restoration, replacement, or acquisition of an equivalent resource) and then states that the measure of damages shall not be limited by the amount of the first two listed purposes. This context makes it obvious that § 107(f)(l)’s “shall not be limited by” language was not designed to afford DOI the liberty of mandating a lesser measure of damages in all or most cases; rather, the measure of damages must not only be sufficient to cover the intended restoration or replacement uses in the usual case but may in some cases exceed restoration cost by incorporating interim lost use value as well. Interior posits still another reading of the “shall not be limited by” phrase: when restoration cost is used as the basic measure of damages, it is not to be a “ceiling” on damages. Interior’s regulations incorporate this view: one regulation provides that, “[i]f restoration or replacement is to form the basis of the measure of damages, the diminution of use values during the period of time required to obtain restoration or replacement may also be included in the measure of damages.” 43 C.F.R. § 11.84(g)(1). It seems strange, however, that Congress would single out one alternative measure of damages (restoration costs) and legislate specially to insure that interim use value damages would be added to it, at the same time it was content to let DOI set damages at the lowest amount calculable by any acceptable standard. The absurdity of this reading surfaces when we consider what happens when use value weighs in at a lower cost than restoration, say $4 million versus $5 million. Use value is used exclusively, and damages are set at $4 million. But if restoration should weigh in at $3 million, damages can include additional millions for interim lost use, bringing the total beyond the $4 million figure. See 43 C.F.R. § 11.84(g)(1). Surely Congress had no such mischievous result in mind. Ultimately, notwithstanding Interior’s and Industry’s attempts to generate “ambiguities” in the statutory text, § 107(f)(1) of CERCLA evinces a clear congressional intent to make restoration costs the basic measure of damages. 3. Superfund Provisions CERCLA’s Superfund provisions lend additional weight to our conclusion that Interior’s “lesser of” rule is not true to the statute. In CERCLA as originally enacted, public trustees could rely on Superfund money to pay for restoration in cases where they could not recover money from the polluters themselves (for example, where the responsible party had become insolvent, or where the responsible party had engaged in secret dumping and thus could not be identified). SARA cut off the availability of Superfund money for natural resource restoration in 1986, but the statutory provisions governing Superfund remain on the books and provide evidence of Congress’ intent to require responsible parties to pay restoration costs. Under CERCLA, Superfund monies can be spent to redress harm to natural resources only to (1) assess the extent of the damages, and to (2) finance government trustees’ “efforts in the restoration, rehabilitation, or replacement or acquiring the equivalent of any natural resources injured, destroyed, or lost as a result of a release of a hazardous substance.” § 111(c)(1)-(2), 42 U.S.C. § 9611(c)(1)-(2). The statute, though, bars a trustee from obtaining Superfund money until it has first “exhausted all administrative and judicial remedies to recover the amount of such claim from persons who may be liable” under § 107 as responsible parties. § 111(b)(2)(A), 42 U.S. C. § 9611(b)(2)(A) (emphasis added). Interi- or’s “lesser of” rule, however, means that in the majority of cases, the trustee cannot “recover the amount of such claim” from the responsible parties since use-based damages will be less. So once again, Interior’s rule appears to be out of sync with the statutory scheme and with CERC-LA’s decided emphasis on making polluters pay for restoration of spoiled resources. 4. Settlement Provision CERCLA’s settlement provision provides that a federal trustee may settle a natural resource damages case only “if the potentially responsible party agrees to undertake appropriate actions necessary to protect and restore the natural resources damaged by [the] release or threatened release of hazardous substances.” § 122(j)(2), 42 U.S. C. § 9622(j)(2). Interior’s “lesser of” rule is out of step with this settlement provision as well: taken together, they establish a ragged-edged scheme whereby a responsible party can settle only if it pays restoration costs, but those restoration costs will usually be more than it stands to lose by trying the ease, if damages are awarded in court under the “lesser of” rule. Normally, a rational polluter would not settle for an amount larger than its potential liability. Thus, we should be reluctant to attribute to Congress a Machiavellian intent to allow Interior to undermine its own settlement provision. The fact that Congress insisted on restoration costs as a floor for settlements shows it must have intended a similar measure of damages to operate in the litigation itself. 5. Double Recovery Provision Section § 107(f)(1) provides that there shall be no “double recovery” against a responsible party, for “natural resource damages, including the costs of damage assessment or restoration, rehabilitation, or acquisition.” 42 U.S.C. § 9607(f)(1). This statutory language is yet another indication that Congress considered “recovery” for “natural resource damages” to “in-clud[e] the costs of ... restoration, rehabilitation, or acquisition.” 6. CERCLA and the Clean Water Act The “lesser of” rule is also inconsistent with § 311(f)(4) and (5) of the Clean Water Act, to which Interior’s natural resource damage regulations are applicable in accordance with § 301(c)(1) of CERCLA. Section 311 of the Clean Water Act provides that damages recoverable for releases of hazardous substances or oil covered by the CWA “shall include any costs or expenses incurred by the Federal Government or any State government in the restoration or replacement of natural resources damaged or destroyed.” 33 U.S.C. § 1321(f)(5). Thus, the CWA expressly establishes restoration cost as the standard measure of damages. Interior nonetheless takes the position that its “lesser of” rule promulgated under CERCLA trumps the CWA standard. DOI points to § 304(c) of CERCLA, which states that “[i]n any case in which any provision of section 311 of the [CWA] is determined to be in conflict with any provisions of [CERCLA], the provisions of [CERCLA] shall apply.” 42 U.S.C. § 9654(c). Interi- or’s position of course assumes a conflict between the two statutes. We perceive none; quite the contrary. The CWA provides that damages must “include” restoration cost, while CERCLA provides that recovered sums must be spent on restoration and “shall not be limited by” restoration cost. These directives are in harmony: restoration is the basic measure of damages, but damages can exceed restoration cost in some cases. A compatible reading of the two statutes reinforces our view that restoration costs were the intended basis for damages in CERCLA and that there is no authorization for DOI to abandon Congress’ strong preference for restoration, clearly expressed in two separate statutes enacted within three years of one another. C. Legislative History of CERCLA The text and structure, of CERCLA indicate clearly to us that Congress intended restoration costs to be the basic measure of recovery for harm to natural resources. We next examine the legislative history of CERCLA to ascertain if there are any countervailing indications to our conclusion and also to check on Interior’s assertions that certain parts of the history are inconsistent with our conclusion and so render the statute ambiguous within the meaning of Chevron. Far from finding these arguments persuasive, we conclude that the legislative history of CERCLA — both in its original enactment in 1980 and in its amendment and reenactment in 1986 — reinforces our interpretation of the text. 1. The Enactment of CERCLA in 1980 The legislative history of CERCLA confirms that restoration costs were intended to be the presumptive measure of recovery. Senate proponents of the legislation, in the committee report and on the Senate floor, repeatedly emphasized that their primary objective in assessing damages for public resources was to achieve restoration. The history of the damages provision of CERCLA documents further Congress’ intent to broaden government trustees’ recovery beyond lost use value. As reported to the Senate floor, CERCLA’s forerunner, S. 1480, allowed recovery for, inter alia, the following three categories of damages: (C) any injury to, destruction of, or loss of natural resources, including the reasonable costs of assessing such injury, destruction, or loss; (D) any loss of use of any natural resources, without regard to the ownership or management of such resources; (E) any loss of income or profits or impairment of earning capacity resulting from personal injury or from injury to or destruction of real or personal property or natural resources, without regard to the ownership of such property or resources.... S. 1480, 96th Cong., 2d Sess. § 4(a)(2), reprinted in 1 Legislative History, supra note 19, at 487-88 (emphasis added). Although (D) and (E), which related to private party recovery, were later dropped from the bill, they evidence a sharp contrast with the language of (C), which governed recovery by public trustees (and which was retained in the enacted version of CERC-LA). Private parties could recover damages only for lost use values, but public trustees were to be allowed under the language of (C) to recover for the loss of the natural resources themselves, based presumably on some measure other than lost use. The draft of S. 1480 is even more instructive when viewed alongside the 1978 amendments to the Outer Continental Shelf Lands Act (OCSLA), from which the language of S. 1480 appears to have been borrowed. Section 303(a)(2) of OCSLA authorizes damage claims for, inter alia, the following: (C) injury to, or destruction of, natural resources; (D) loss of use of natural resources; (E) loss of profits or impairment of earning capacity due to injury to, or destruction of, real or personal property or natural resources.... 43 U.S.C. § 1813(a)(2)(C)-(E). As was the case with the proposed version of CERC-LA, OCSLA makes the damages under paragraph (C) available only to the federal or state governments, while (D) and (E) relate to private party recovery. OCSLA § 303(b), 43 U.S.C. § 1813(b). The legislative history of paragraph (C) of OCSLA makes it clear that restoration costs are the standard of recovery. See H.R.Rep. No. 590, 95th Cong., 1st Sess. 182 (1977), 1978 U.S.Code Cong. & Admin.News 1450, 1588 (“If natural resources are damaged or destroyed by an oil discharge, Federal or State governments may recover the costs and expenses of restoring, repairing, or replacing such resources.”); see also H.R. Conf.Rep. No. 1474, 95th Cong., 2d Sess. 131 (1978), 1978 U.S.Code Cong. & Admin. News 1450, 1730. Given the similarity between OCSLA and the CERCLA § 107(a)(C) provision for recovery of “damages for injury to, destruction of, or loss of natural resources,” Congress’ use of restoration as the standard for damages under OCSLA provides further evidence that CERCLA likewise envisions restoration cost as the primary standard of recovery. Interior, however, advances a supposed “ambiguity” in the legislative history of CERCLA. The 1980 Senate report on CERCLA contains the following statement: The Committee received testimony indicating that both short- and long-term damages to natural resources resulted from releases of hazardous substances and that standardized techniques for assessing both the biological and economic damages from such releases should be developed. Testimony also indicated that it was appropriate and necessary for the State or in some instances the Federal Government acting as trustee for such resources to seek restitution for such damages or restoration of such resources. S.Rep. No. 848, supra note 10, at 84 (emphasis added). Interior argues that the use of the word “or” in the italicized phrase indicates that Congress did not necessarily envision restoration costs as the basic measure of damages. Resp. Br. 29. We see no basis for Interior’s assumption that the word “restitution” is equivalent to “use value.” Furthermore, we do not read the statute as mandating that restoration costs are the minimum measure in every natural resource case. We (though not petitioners) acknowledge some degree of latitude on the part of DOI to establish use value as the measure of damages in some class or classes of cases. The precise question before us is whether DOI can use the “lesser of” rule to decide when use value will be the chosen measure and when restoration costs will be chosen instead. The appearance of the word “or” in the Senate report is completely unresponsive to this issue. 2. The Enactment of SARA in 1986 CERCLA’s “shall not be limited by” language, its mandate that recovered funds be used solely for restoration activities, and the statements of its sponsors and supporters during its passage in 1980 all point in one direction: a distinct preference for restoration costs as the normative standard for damages. Congress’ enactment of SARA in 1986 also provides strong evidence that a restoration measure of damages was the statute’s original intent. Of controlling importance in the SARA phase is a House report indicating that, while the “shall not be limited by” language of the original statute would be retained, Interi- or’s demonstrated “confusion” about what that phrase meant should be resolved in light of Congress’ strong emphasis on restoration of resources. While not altering the relevant phrases of § 107(f) in any basic way, SARA changed the permissible uses for damages from “restore, rehabilitate, or acquire the equivalent” to “restore, replace, or acquire the equivalent,” in order to avoid the redundancy of “restore” and “rehabilitate,” and to conform the exclusive use clause to the language of the “shall not be limited by” damages clause. See H.R.Rep. No. 253(IV), supra note 8, at 50 (emphasis added). In the accompanying Report of the House Committee on Merchant Marine and Fisheries, explicating how the new § 107(f)(1) would work, its sponsors made their intent unmistakable that restoration costs were to be the preferred measure of damages. The committee report indicated that the “shall not be limited by” passage, while “essentially a restatement of the language of” the 1980 version, was aimed at ending what had been a “source of some confusion.” H.R.Rep. No. 253(IV), supra note 8, at 50. “It is clear from [the] language [of § 107(f)(1)] that the primary purpose of the resource damage provisions of CERCLA is the restoration or replacement of natural resources damaged by unlawful releases of hazardous substances.” Id. (emphasis added). Such an unequivocal statement of purpose is irreconcilable with DOI’s “lesser of” rule, which would in a majority of cases risk underfunded, half-finished restoration projects. The same House report went on to explain: [T]he final clause [dealing with use of damages to acquire a suitable equivalent resource] is necessary because a situation could arise in which the amount of damages caused by a release of hazardous substances is in excess of the amount that could realistically or productively be used to restore or replace those resources. That is, the total amount of damages may include the costs of restoration and the value of all the lost uses of the damaged resources ... from the time of the release up to the time of restoration. Since the damages contemplated by CERCLA include both, the total amount of damages recoverable would exceed the restoration costs alone. The Committee therefore intends than [sic: probably should be “that”] any excess funds recovered shall be used, in such an instance, for the third purpose spelled out in the language of the amendment, which is to “acquire the equivalent of the damaged resource.” H.R.Rep. No. 253(IV), supra note 8, at 50 (emphasis added). The House report thus explicitly assumes that damages “contemplated by CERCLA” will normally include restoration costs at a minimum, plus interim lost-use value in appropriate cases. (This House amendment to § 107(f)(1) was adopted by the Conference Committee, H.R.Conf.Rep. No. 962, 99th Cong., 2d Sess. 204-05 (1986), and Representative Jones, a SARA sponsor, referred to H.R. Rep. No. 253(IV) as a good source of explanation for the SARA amendments. 132 Cong.Rec. H9612 (daily ed. Oct. 8, 1986).) In the face of this passage, the plausibility of the “lesser of” rule, which purposely allows damage recoveries to be set at an amount too small to accomplish restoration (or replacement or acquisition of an equivalent resource), becomes suspect indeed. Interior’s effort to discount the House report fails. Citing the passage quoted above, Interior states: “Although the report recognizes that damages measured might be found to exceed restoration costs, that does not mean that recovery should exceed restoration costs.” Resp. Br. 33 (emphasis in original). We are at a loss to see how Interior can draw such a distinction between “damages” and “recovery” when the key phrase of the sentence is “damages recoverable.” In sum, Interi- or has not dissuaded us from the view that Congress in its 1986 SARA amendments to CERCLA reiterated its intention to make restoration costs the basic measure of recovery. SARA’s legislative history also indicates that Congress consciously paralleled CERCLA’s provision of Superfund monies for restoration activities and its imposition of liability on responsible parties to defray the expenses of those activities. A House report on SARA explicitly refers to § lll(c)(2)’s provision for using Superfund monies as the model for § 107(f)(l)’s limitation on the uses of recovered damages, noting: This language [of § 107(f)(1) ] is modeled after section 111(c)(2) of CERCLA ... but the money is recovered from the responsible party, not from the fund itself. H.R.Rep. No. 253(IV), supra note 8, at 50. If CERCLA’s damages provision was expressly “modeled after” Superfund’s provision allowing claims for restoration costs, the two provisions must incorporate similar theories of recovery. In sum, Interior’s rule preventing government trustees from recovering the full cost of restoration clearly runs against the statutory grain. 3. Congress’ Rejection of the Premises Underlying the “Lesser-Of” Rule CERCLA’s legislative history undergirds its textual focus on recovering restoration costs as the primary aim of the natural resource damages provisions. Furthermore, it shows that Congress soundly rejected the two basic premises underlying Interior’s “lesser of” rule — first, that the common-law measure of damages is appropriate in the natural resource context, and second, that it is economically inefficient to restore a resource whose use value is less than the cost of restoration. a. CERCLA and the Common-Law Measure of Damages DOI and Industry Intervenors argue that Congress intended that damages under CERCLA would be calculated according to traditional common-law rules. Accepting for the sake of argument the contention that the “lesser of” rule reflects the common law, support for the proposition that Congress adopted common-law damage standards wholesale into CERCLA is slim to nonexistent. DOI contends that Congress meant to adopt traditional methods of damage measurement, “[i]n the absence of clearly expressed Congressional intent to deviate from [the] common law rule.” 51 Fed.Reg. at 27,705. The legislative history illustrates, however, that a motivating force behind the CERCLA natural resource damage provisions was Congress’ dissatisfaction with the common law. Indeed, one wonders why Congress would have passed a new damage provision at all if it were content with the common law. Nor are we persuaded by Interior’s reference to a colloquy on the Senate floor between Senator Simpson, a vocal opponent of CERCLA in committee who ultimately voted in favor of the bill, and Senator Stafford, a CERCLA sponsor. Senator Simpson stated: “I ... trust that the traditional legal rules for calculating of damages for injury in tort will be observed as part of cost effectiveness,” citing as an example the measurement of damages as the lesser of lost use value or restoration cost. 126 Cong.Rec. 30,986 (1980). Interi- or quotes Senator Stafford as responding: “Yes, the Senator is correct.” Resp. Br. 30. In all fairness, Interior’s brief indicates by an ellipsis with the customary three dots that material between the query and the answer has been left out. The reality, however, is that in the interim Senator Simpson turned away from the measure-of-damages topic entirely and discussed in over 200 words an entirely unrelated provision of the statute before Senator Stafford said, “Yes, the Senator is correct,” in response to a specific point on the unrelated topic. Based on what we read, there was no completed exchange between the two Senators on the subject at hand. In the face of Congress’ stated dissatisfaction with the common law, Interi- or’s reliance on this colloquy to justify its adherence to common-law damage measures is misplaced. b. CERCLA and Economic Efficiency Alternatively, Interior justifies the “lesser of” rule as being economically efficient. Under DOI’s economic efficiency view, making restoration cost the measure of damages would be a waste of money whenever restoration would cost more than the use value of the resource. Its explanation of the proposed rules included the following statement: [I]f use value is higher than the cost of restoration or replacement, then it would be more rational for society to be compensated for the cost to restore or replace the lost resource than to be compensated for the lost use. Conversely, if restoration or replacement costs are higher than the value of uses foregone, it is rational for society to compensate individuals for their lost uses rather than the cost to restore or replace the injured natural resource. 50 Fed.Reg. at 52,141. See also 51 Fed. Reg. at 27,704 (“lesser of" rule “promotes a rational allocation of society’s assets”). This is nothing more or less than cost-benefit analysis: Interior’s rule attempts to optimize social welfare by restoring an injured resource only when the diminution in the resource’s value to society is greater in magnitude than the cost of restoring it. And, acknowledgedly, Congress did intend CERCLA’s natural resource provisions to operate efficiently. For one thing, the Act requires that the assessment of damages and the restoration of injured resources take place as cost-effectively as possible. Moreover, as we have indicated, there is some suggestion in the legislative history that Congress intended recovery not to encompass restoration cost where restoration is infeasible or where its cost is grossly disproportionate to use value. See supra note 7. The fatal flaw of Interior’s approach, however, is that it assumes that natural resources are fungible goods, just like any other, and that the value to society generated by a particular resource can be accurately measured in every ease — assumptions that Congress apparently rejected. As the foregoing examination of CERC-LA’s text, structure and legislative history illustrates, Congress saw restoration as the presumptively correct remedy for injury to natural resources. To say that Congress placed a thumb on the scales in favor of restoration is not to say that it forswore the goal of efficiency. “Efficiency,” standing alone, simply means that the chosen policy will dictate the result that achieves the greatest value to society. Whether a particular choice is efficient depends on how the various alternatives are valued. Our reading of CERCLA does not attribute to Congress an irrational dislike of “efficiency”; rather, it suggests that Congress was skeptical of the ability of human beings to measure the true “value” of a natural resource. Indeed, even the common law recognizes that restoration is the proper remedy for injury to property where measurement of damages by some other method will fail to compensate fully for the injury. Congress’ refusal to view use value and restoration cost as having equal presumptive legitimacy merely recognizes that natural resources have value that is not readily measured by traditional mean