(Slip Opinion) OCTOBER TERM, 1999 1 Syllabus NOTE: Where it is feasible, a syllabus (headnote) will be released, as is being done in connection with this case, at the time the opinion is issued. The syllabus constitutes no part of the opinion of the Court but has been prepared by the Reporter of Decisions for the convenience of the reader. See United States v. Detroit Timber & Lumber Co., 200 U. S. 321, 337. SUPREME COURT OF THE UNITED STATES Syllabus FRIENDS OF THE EARTH, INC., ET AL. v. LAIDLAW ENVIRONMENTAL SERVICES (TOC), INC. CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR THE FOURTH CIRCUIT No. 98­822. Argued October 12, 1999- Decided January 12, 2000 Defendant-respondent Laidlaw Environmental Services (TOC), Inc., bought a facility in Roebuck, South Carolina, that included a waste- water treatment plant. Shortly thereafter, the South Carolina De- partment of Health and Environmental Control (DHEC), acting un- der the Clean Water Act (Act), 33 U. S. C. §1342(a)(1), granted Laidlaw a National Pollutant Discharge Elimination System (NPDES) permit. The permit authorized Laidlaw to discharge treated water into the North Tyger River, but limited, among other things, the discharge of pollutants into the waterway. Laidlaw began to discharge various pollutants into the waterway; these discharges, particularly of mercury, an extremely toxic pollutant, repeatedly ex- ceeded the limits set by the permit. On April 10, 1992, plaintiff-petitioners Friends of the Earth and Citizens Local Environmental Action Network, Inc. (referred to col- lectively here, along with later joined plaintiff-petitioner Sierra Club, as "FOE"), notified Laidlaw of their intention to file a citizen suit against it under the Act, 33 U. S. C. §1365(a), after the expiration of the requisite 60-day notice period. DHEC acceded to Laidlaw's re- quest to file a lawsuit against the company. On the last day before FOE's 60-day notice period expired, DHEC and Laidlaw reached a settlement requiring Laidlaw to pay $100,000 in civil penalties and to make "every effort" to comply with its permit obligations. On June 12, 1992, FOE filed this citizen suit against Laidlaw, al- leging noncompliance with the NPDES permit and seeking declara- tory and injunctive relief and an award of civil penalties. Laidlaw moved for summary judgment on the ground that FOE lacked Article III standing to bring the lawsuit. After examining affidavits and 2 FRIENDS OF EARTH, INC. v. LAIDLAW ENVI- RONMENTAL SERVICES (TOC), INC. Syllabus deposition testimony from members of the plaintiff organizations, the District Court denied the motion, finding that the plaintiffs had standing. The District Court also denied Laidlaw's motion to dismiss on the ground that the citizen suit was barred under §1365(b)(1)(B) by DHEC's prior action against the company. After FOE initiated this suit, but before the District Court rendered judgment on January 22, 1997, Laidlaw violated the mercury discharge limitation in its permit 13 times and committed 13 monitoring and 10 reporting viola- tions. In issuing its judgment, the District Court found that Laidlaw had gained a total economic benefit of $1,092,581 as a result of its ex- tended period of noncompliance with the permit's mercury discharge limit; nevertheless, the court concluded that a civil penalty of $405,800 was appropriate. In particular, the District Court found that the judgment's "total deterrent effect" would be adequate to forestall future violations, given that Laidlaw would have to reim- burse the plaintiffs for a significant amount of legal fees and had it- self incurred significant legal expenses. The court declined to order injunctive relief because Laidlaw, after the lawsuit began, had achieved substantial compliance with the terms of its permit. FOE appealed as to the amount of the District Court's civil penalty judgment, but did not appeal the denial of declaratory or injunctive relief. The Fourth Circuit vacated the District Court's order and re- manded with instructions to dismiss the action. Assuming, argu- endo, that FOE initially had standing, the appellate court held that the case had become moot once Laidlaw complied with the terms of its permit and the plaintiffs failed to appeal the denial of equitable relief. Citing Steel Co. v. Citizens for Better Environment, 523 U. S. 83, the court reasoned that the only remedy currently available to FOE, civil penalties payable to the Government, would not redress any in- jury FOE had suffered. The court added that FOE's failure to obtain relief on the merits precluded recovery of attorneys' fees or costs be- cause such an award is available only to a "prevailing or substan- tially prevailing party" under §1365(d). According to Laidlaw, the entire Roebuck facility has since been permanently closed, disman- tled, and put up for sale, and all discharges from the facility have permanently ceased. Held: The Fourth Circuit erred in concluding that a citizen suitor's claim for civil penalties must be dismissed as moot when the defen- dant, after commencement of the litigation, has come into compliance with its NPDES permit. Pp. 8­25. (a) The Constitution's case-or-controversy limitation on federal ju- dicial authority, Art. III, §2, underpins both standing and mootness doctrine, but the two inquiries differ in crucial respects. Because the Fourth Circuit was persuaded that the case had become moot, it sim- Cite as: 528 U. S. ____ (2000) 3 Syllabus ply assumed that FOE had initial standing. See Arizonans for Offi- cial English v. Arizona, 520 U. S. 43, 66­67. But because this Court concludes that the Court of Appeals erred as to mootness, this Court has an obligation to assure itself that FOE had Article III standing at the outset of the litigation. Pp. 8­9. (b) FOE had Article III standing to bring this action. This Court has held that to satisfy Article III's standing requirements, a plaintiff must show "injury in fact," causation, and redressability. Lujan v. Defenders of Wildlife, 504 U. S. 555, 560­561. An association has standing to bring suit on behalf of its members when its members would have standing to sue in their own right, the interests at stake are germane to the organization's purpose, and neither the claim as- serted nor the relief requested requires individual members' partici- pation in the lawsuit. Hunt v. Washington State Apple Advertising Comm'n, 432 U. S. 333, 343. The relevant showing for Article III standing is not injury to the environment but injury to the plaintiff. To insist on the former rather than the latter is to raise the standing hurdle higher than the necessary showing for success on the merits in a citizen's NPDES permit enforcement suit. Here, injury in fact was adequately documented by the affidavits and testimony of FOE members asserting that Laidlaw's pollutant discharges, and the affi- ants' reasonable concerns about the effects of those discharges, di- rectly affected those affiants' recreational, aesthetic, and economic in- terests. See, e.g., Sierra Club v. Morton, 405 U. S. 727, 735. These submissions present dispositively more than the mere "general aver- ments" and "conclusory allegations" found inadequate in Lujan v. Na- tional Wildlife Federation, 497 U. S. 871, 888, or the " `some day' in- tentions" to visit endangered species halfway around the world held insufficient in Defenders of Wildlife. 504 U. S., at 564. Pp. 9­13. (c) Laidlaw argues that FOE lacked standing to seek civil penal- ties payable to the Government, because such penalties offer no re- dress to citizen plaintiffs. For a plaintiff who is injured or threatened with injury due to illegal conduct ongoing at the time of suit, a sanc- tion that effectively abates that conduct and prevents its recurrence provides a form of redress. Civil penalties can fit that description. Insofar as they encourage defendants to discontinue current viola- tions and deter future ones, they afford redress to citizen plaintiffs injured or threatened with injury as a result of ongoing unlawful conduct. The Court need not explore the outer limits of the principle that civil penalties provide sufficient deterrence to support redress- ability, because the civil penalties sought here carried a deterrent ef- fect that made it likely, as opposed to merely speculative, that the penalties would redress FOE's injuries- as the District Court rea- sonably found when it assessed a penalty of $405,800. Steel Co. is 4 FRIENDS OF EARTH, INC. v. LAIDLAW ENVI- RONMENTAL SERVICES (TOC), INC. Syllabus not to the contrary. That case held that private plaintiffs may not sue to assess penalties for wholly past violations, 523 U. S., at 106­ 107, but did not address standing to seek penalties for violations ongo- ing at the time of the complaint that could continue into the future if undeterred, see id., at 108. Pp. 13­17. (d) FOE's civil penalties claim did not automatically become moot once the company came into substantial compliance with its permit. A defendant's voluntary cessation of a challenged practice ordinarily does not deprive a federal court of its power to determine the legality of the practice. City of Mesquite v. Aladdin's Castle, Inc., 455 U. S. 283, 289. If it did, courts would be compelled to leave the defendant free to return to its old ways. Thus, the standard for determining whether a case has been mooted by the defendant's voluntary conduct is stringent: A case might become moot if subsequent events make it absolutely clear that the allegedly wrongful behavior could not rea- sonably be expected to recur. United States v. Concentrated Phos- phate Export Assn., Inc., 393 U. S. 199, 203. The heavy burden of persuading the court that the challenged conduct cannot reasonably be expected to recur lies with the party asserting mootness. Ibid. The Court of Appeals incorrectly conflated this Court's case law on initial standing, see, e.g., Steel Co., with its case law on mootness, see, e.g., City of Mesquite. Such confusion is understandable, given this Court's repeated description of mootness as "the doctrine of standing set in a time frame: The requisite personal interest that must exist at the commencement of the litigation (standing) must continue throughout its existence (mootness)." E.g., Arizonans, 520 U. S., at 68, n. 22. Careful reflection, however, reveals that this description of mootness is not comprehensive. For example, a defendant claiming that its voluntary compliance moots a case bears a formidable bur- den. By contrast, it is the plaintiff's burden, in a lawsuit brought to force compliance, to establish standing by demonstrating that, if un- checked by the litigation, the defendant's allegedly wrongful behavior will likely occur or continue and that the threatened injury is cer- tainly impending. Whitmore v. Arkansas, 495 U. S. 149, 158. The plain lesson is that there are circumstances in which the prospect that a defendant will engage in (or resume) harmful conduct may be too speculative to support standing, but not too speculative to over- come mootness. Further, if mootness were simply "standing set in a time frame," the exception to mootness for acts that are "capable of repetition, yet evading review" could not exist. See, e.g., Olmstead v. L. C., 527 U. S. ___, ___, n. 6. Standing admits of no similar exception; if a plaintiff lacks standing at the time the action commences, the fact that the dispute is capable of repetition yet evading review will not entitle the complainant to a federal judicial forum. See, e.g., Steel Cite as: 528 U. S. ____ (2000) 5 Syllabus Co., 523 U. S., at 109. Standing doctrine ensures, among other things, that the resources of the federal courts are devoted to dis- putes in which the parties have a concrete stake. Yet by the time mootness is an issue, abandonment of the case may prove more wasteful than frugal. Courts have no license to retain jurisdiction over cases in which one or both of the parties plainly lacks a con- tinuing interest, see, e.g., Arizonans, 520 U. S., at 67, but the foregoing examples highlight an important difference between the two doc- trines, see generally Honig v. Doe, 484 U. S. 305, 329­332 (REHNQUIST, C. J., concurring). Laidlaw's argument that FOE doomed its own civil penalty claim to mootness by failing to appeal the denial of injunctive relief miscon- ceives the statutory scheme. Under §1365(a), the district court has discretion to determine which form of relief is best suited to abate current violations and deter future ones. See Weinberger v. Ro- mero-Barcelo, 456 U. S. 305, 313. Denial of injunctive relief does not necessarily mean that the district court has concluded there is no prospect of future violations to deter. Indeed, it meant no such thing in this case; the District Court denied injunctive relief, but expressly based its award of civil penalties on the need for deterrence. A dis- trict court properly may conclude that an injunction would be too in- trusive, because it could entail continuing and burdensome superin- tendence of the permit holder's activities by a federal court. See City of Mesquite, 455 U. S., at 289. Both Laidlaw's permit compliance and the facility closure might moot this case, but only if one or the other event made it absolutely clear that violations could not reasonably be expected to recur. Concentrated Phosphate Export Assn., 393 U. S., at 203. These are disputed factual matters that have not been aired in the lower courts; they remain open for consideration on remand. Pp. 18­23. (e) This Court does not resolve FOE's argument that it is entitled to attorneys' fees on the theory that a plaintiff can be a "prevailing party" under §1365(d) if it was the "catalyst" that triggered a favor- able outcome. Although the Circuits have divided as to the continu- ing validity of the catalyst theory following Farrar v. Hobby, 506 U. S. 103, it would be premature for this Court to address the ques- tion here. The District Court stayed the time for a petition for attor- neys' fees until the time for appeal had expired or until any appeal was resolved. Thus, when the Fourth Circuit addressed the avail- ability of counsel fees, no order was before it either denying or awarding fees. It is for the District Court, not this Court, to address in the first instance any request for reimbursement of costs, includ- ing fees. Pp. 23­25. 149 F. 3d 303, reversed and remanded. 6 FRIENDS OF EARTH, INC. v. LAIDLAW ENVI- RONMENTAL SERVICES (TOC), INC. Syllabus GINSBURG, J., delivered the opinion of the Court, in which REHNQUIST, C. J., and STEVENS, O'CONNOR, KENNEDY, SOUTER, and BREYER, JJ., joined. STEVENS, J., and KENNEDY, J., filed concurring opinions. SCALIA, J., filed a dissenting opinion, in which THOMAS, J., joined. Cite as: 528 U. S. ____ (2000) 1 Opinion of the Court NOTICE: This opinion is subject to formal revision before publication in the preliminary print of the United States Reports. Readers are requested to notify the Reporter of Decisions, Supreme Court of the United States, Wash- ington, D. C. 20543, of any typographical or other formal errors, in order that corrections may be made before the preliminary print goes to press. SUPREME COURT OF THE UNITED STATES _________________ No. 98­822 _________________ FRIENDS OF THE EARTH, INCORPORATED, ET AL., PETITIONERS v. LAIDLAW ENVIRONMENTAL SERVICES (TOC), INC. ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR THE FOURTH CIRCUIT [January 12, 2000] JUSTICE GINSBURG delivered the opinion of the Court. This case presents an important question concerning the operation of the citizen-suit provisions of the Clean Water Act. Congress authorized the federal district courts to entertain Clean Water Act suits initiated by "a person or persons having an interest which is or may be adversely affected." 33 U. S. C. §§1365(a), (g). To impel future com- pliance with the Act, a district court may prescribe injunc- tive relief in such a suit; additionally or alternatively, the court may impose civil penalties payable to the United States Treasury. §1365(a). In the Clean Water Act citizen suit now before us, the District Court determined that injunctive relief was inappropriate because the defendant, after the institution of the litigation, achieved substantial compliance with the terms of its discharge permit. 956 F. Supp. 588, 611 (SC 1997). The court did, however, assess a civil penalty of $405,800. Id., at 610. The "total deterrent effect" of the penalty would be adequate to forestall future violations, the court reasoned, taking into account that the defendant "will be required to reimburse plaintiffs for a significant amount of legal fees and has, 2 FRIENDS OF EARTH, INC. v. LAIDLAW ENVI- RONMENTAL SERVICES (TOC), INC. Opinion of the Court itself, incurred significant legal expenses." Id., at 610­ 611. The Court of Appeals vacated the District Court's order. 149 F. 3d 303 (CA4 1998). The case became moot, the appellate court declared, once the defendant fully complied with the terms of its permit and the plaintiff failed to appeal the denial of equitable relief. "[C]ivil penalties payable to the government," the Court of Appeals stated, "would not redress any injury Plaintiffs have suffered." Id., at 307. Nor were attorneys' fees in order, the Court of Appeals noted, because absent relief on the merits, plain- tiffs could not qualify as prevailing parties. Id., at 307, n. 5. We reverse the judgment of the Court of Appeals. The appellate court erred in concluding that a citizen suitor's claim for civil penalties must be dismissed as moot when the defendant, albeit after commencement of the litiga- tion, has come into compliance. In directing dismissal of the suit on grounds of mootness, the Court of Appeals incorrectly conflated our case law on initial standing to bring suit, see, e.g., Steel Co. v. Citizens for Better Environ- ment, 523 U. S. 83 (1998), with our case law on post- commencement mootness, see, e.g., City of Mesquite v. Aladdin's Castle, Inc., 455 U. S. 283 (1982). A defendant's voluntary cessation of allegedly unlawful conduct ordi- narily does not suffice to moot a case. The Court of Ap- peals also misperceived the remedial potential of civil penalties. Such penalties may serve, as an alternative to an injunction, to deter future violations and thereby re- dress the injuries that prompted a citizen suitor to com- mence litigation. IA In 1972, Congress enacted the Clean Water Act (Act), also known as the Federal Water Pollution Control Act, 86 Cite as: 528 U. S. ____ (2000) 3 Opinion of the Court Stat. 816, as amended, 33 U. S. C. §1251 et seq. Section 402 of the Act, 33 U. S. C. §1342, provides for the issuance, by the Administrator of the Environmental Protection Agency (EPA) or by authorized States, of National Pollut- ant Discharge Elimination System (NPDES) permits. NPDES permits impose limitations on the discharge of pollutants, and establish related monitoring and reporting requirements, in order to improve the cleanliness and safety of the Nation's waters. Noncompliance with a permit constitutes a violation of the Act. §1342(h). Under §505(a) of the Act, a suit to enforce any limitation in an NPDES permit may be brought by any "citizen," defined as "a person or persons having an interest which is or may be adversely affected." 33 U. S. C. §§1365(a), (g). Sixty days before initiating a citizen suit, however, the would-be plaintiff must give notice of the alleged violation to the EPA, the State in which the alleged violation oc- curred, and the alleged violator. §1365(b)(1)(A). "[T]he purpose of notice to the alleged violator is to give it an opportunity to bring itself into complete compliance with the Act and thus . . . render unnecessary a citizen suit." Gwaltney of Smithfield, Ltd. v. Chesapeake Bay Founda- tion, Inc., 484 U. S. 49, 60 (1987). Accordingly, we have held that citizens lack statutory standing under §505(a) to sue for violations that have ceased by the time the com- plaint is filed. Id., at 56­63. The Act also bars a citizen from suing if the EPA or the State has already com- menced, and is "diligently prosecuting," an enforcement action. 33 U. S. C. §1365(b)(1)(B). The Act authorizes district courts in citizen-suit pro- ceedings to enter injunctions and to assess civil penalties, which are payable to the United States Treasury. §1365(a). In determining the amount of any civil penalty, the district court must take into account "the seriousness of the violation or violations, the economic benefit (if any) resulting from the violation, any history of such violations, 4 FRIENDS OF EARTH, INC. v. LAIDLAW ENVI- RONMENTAL SERVICES (TOC), INC. Opinion of the Court any good-faith efforts to comply with the applicable re- quirements, the economic impact of the penalty on the violator, and such other matters as justice may require." §1319(d). In addition, the court "may award costs of litiga- tion (including reasonable attorney and expert witness fees) to any prevailing or substantially prevailing party, whenever the court determines such award is appropri- ate." §1365(d). B In 1986, defendant-respondent Laidlaw Environmental Services (TOC), Inc., bought a hazardous waste incinera- tor facility in Roebuck, South Carolina, that included a wastewater treatment plant. (The company has since changed its name to Safety-Kleen (Roebuck), Inc., but for simplicity we will refer to it as "Laidlaw" throughout.) Shortly after Laidlaw acquired the facility, the South Carolina Department of Health and Environmental Con- trol (DHEC), acting under 33 U. S. C. §1342(a)(1), granted Laidlaw an NPDES permit authorizing the company to discharge treated water into the North Tyger River. The permit, which became effective on January 1, 1987, placed limits on Laidlaw's discharge of several pollutants into the river, including- of particular relevance to this case- mercury, an extremely toxic pollutant. The permit also regulated the flow, temperature, toxicity, and pH of the effluent from the facility, and imposed monitoring and reporting obligations. Once it received its permit, Laidlaw began to discharge various pollutants into the waterway; repeatedly, Laid- law's discharges exceeded the limits set by the permit. In particular, despite experimenting with several technologi- cal fixes, Laidlaw consistently failed to meet the permit's stringent 1.3 ppb (parts per billion) daily average limit on mercury discharges. The District Court later found that Cite as: 528 U. S. ____ (2000) 5 Opinion of the Court Laidlaw had violated the mercury limits on 489 occasions between 1987 and 1995. 956 F. Supp., at 613­621. On April 10, 1992, plaintiff-petitioners Friends of the Earth (FOE) and Citizens Local Environmental Action Network, Inc. (CLEAN) (referred to collectively in this opinion, together with later joined plaintiff-petitioner Sierra Club, as "FOE") took the preliminary step neces- sary to the institution of litigation. They sent a letter to Laidlaw notifying the company of their intention to file a citizen suit against it under §505(a) of the Act after the expiration of the requisite 60-day notice period, i.e., on or after June 10, 1992. Laidlaw's lawyer then contacted DHEC to ask whether DHEC would consider filing a lawsuit against Laidlaw. The District Court later found that Laidlaw's reason for requesting that DHEC file a lawsuit against it was to bar FOE's proposed citizen suit through the operation of 33 U. S. C. §1365(b)(1)(B). 890 F. Supp. 470, 478 (SC 1995). DHEC agreed to file a law- suit against Laidlaw; the company's lawyer then drafted the complaint for DHEC and paid the filing fee. On June 9, 1992, the last day before FOE's 60-day notice period expired, DHEC and Laidlaw reached a settlement requir- ing Laidlaw to pay $100,000 in civil penalties and to make " `every effort' " to comply with its permit obligations. 890 F. Supp., at 479­481. On June 12, 1992, FOE filed this citizen suit against Laidlaw under §505(a) of the Act, alleging noncompliance with the NPDES permit and seeking declaratory and injunctive relief and an award of civil penalties. Laidlaw moved for summary judgment on the ground that FOE had failed to present evidence demonstrating injury in fact, and therefore lacked Article III standing to bring the lawsuit. Record, Doc. No. 43. In opposition to this motion, FOE submitted affidavits and deposition testimony from members of the plaintiff organizations. Record, Doc. No. 71 (Exhs. 41­51). The record before the District Court 6 FRIENDS OF EARTH, INC. v. LAIDLAW ENVI- RONMENTAL SERVICES (TOC), INC. Opinion of the Court also included affidavits from the organizations' members submitted by FOE in support of an earlier motion for preliminary injunctive relief. Record, Doc. No. 21 (Exhs. 5­10). After examining this evidence, the District Court denied Laidlaw's summary judgment motion, finding- albeit "by the very slimmest of margins"- that FOE had standing to bring the suit. App. in No. 97­1246 (CA4), pp. 207­208 (Tr. of Hearing 39­40 (June 30, 1993)). Laidlaw also moved to dismiss the action on the ground that the citizen suit was barred under 33 U. S. C. §1365(b)(1)(B) by DHEC's prior action against the com- pany. The United States, appearing as amicus curiae, joined FOE in opposing the motion. After an extensive analysis of the Laidlaw-DHEC settlement and the circum- stances under which it was reached, the District Court held that DHEC's action against Laidlaw had not been "diligently prosecuted"; consequently, the court allowed FOE's citizen suit to proceed. 890 F. Supp., at 499.1 The record indicates that after FOE initiated the suit, but before the District Court rendered judgment, Laidlaw violated the mercury discharge limitation in its permit 13 times. 956 F. Supp., at 621. The District Court also found that Laidlaw had committed 13 monitoring and 10 re- porting violations during this period. Id., at 601. The last recorded mercury discharge violation occurred in January 1995, long after the complaint was filed but about two years before judgment was rendered. Id., at 621. - - - - - - 1 The District Court noted that "Laidlaw drafted the state-court com- plaint and settlement agreement, filed the lawsuit against itself, and paid the filing fee." 890 F. Supp., at 489. Further, "the settlement agreement between DHEC and Laidlaw was entered into with unusual haste, without giving the Plaintiffs the opportunity to intervene." Ibid. The court found "most persuasive" the fact that "in imposing the civil penalty of $100,000 against Laidlaw, DHEC failed to recover, or even to calculate, the economic benefit that Laidlaw received by not complying with its permit." Id., at 491. Cite as: 528 U. S. ____ (2000) 7 Opinion of the Court On January 22, 1997, the District Court issued its judgment. 956 F. Supp. 588 (SC 1997). It found that Laidlaw had gained a total economic benefit of $1,092,581 as a result of its extended period of noncompliance with the mercury discharge limit in its permit. Id., at 603. The court concluded, however, that a civil penalty of $405,800 was adequate in light of the guiding factors listed in 33 U. S. C. §1319(d). 956 F. Supp., at 610. In particular, the District Court stated that the lesser penalty was appro- priate taking into account the judgment's "total deterrent effect." In reaching this determination, the court "consid- ered that Laidlaw will be required to reimburse plaintiffs for a significant amount of legal fees." Id., at 610­611. The court declined to grant FOE's request for injunctive relief, stating that an injunction was inappropriate be- cause "Laidlaw has been in substantial compliance with all parameters in its NPDES permit since at least August 1992." Id., at 611. FOE appealed the District Court's civil penalty judg- ment, arguing that the penalty was inadequate, but did not appeal the denial of declaratory or injunctive relief. Laidlaw cross-appealed, arguing, among other things, that FOE lacked standing to bring the suit and that DHEC's action qualified as a diligent prosecution precluding FOE's litigation. The United States continued to participate as amicus curiae in support of FOE. On July 16, 1998, the Court of Appeals for the Fourth Circuit issued its judgment. 149 F. 3d 303. The Court of Appeals assumed without deciding that FOE initially had standing to bring the action, id., at 306, n. 3, but went on to hold that the case had become moot. The appellate court stated, first, that the elements of Article III stand- ing- injury, causation, and redressability- must persist at every stage of review, or else the action becomes moot. Id., at 306. Citing our decision in Steel Co., the Court of Ap- peals reasoned that the case had become moot because 8 FRIENDS OF EARTH, INC. v. LAIDLAW ENVI- RONMENTAL SERVICES (TOC), INC. Opinion of the Court "the only remedy currently available to [FOE]- civil pen- alties payable to the government- would not redress any injury [FOE has] suffered." Id., at 306­307. The court therefore vacated the District Court's order and remanded with instructions to dismiss the action. In a footnote, the Court of Appeals added that FOE's "failure to obtain relief on the merits of [its] claims precludes any recovery of attorneys' fees or other litigation costs because such an award is available only to a `prevailing or substantially prevailing party.' " Id., at 307, n. 5 (quoting 33 U. S. C. §1365(d)). According to Laidlaw, after the Court of Appeals issued its decision but before this Court granted certiorari, the entire incinerator facility in Roebuck was permanently closed, dismantled, and put up for sale, and all discharges from the facility permanently ceased. Respondent's Sug- gestion of Mootness 3. We granted certiorari, 525 U. S. 1176 (1999), to resolve the inconsistency between the Fourth Circuit's decision in this case and the decisions of several other Courts of Ap- peals, which have held that a defendant's compliance with its permit after the commencement of litigation does not moot claims for civil penalties under the Act. See, e.g., Atlantic States Legal Foundation, Inc. v. Stroh Die Casting Co., 116 F. 3d 814, 820 (CA7), cert. denied, 522 U. S. 981 (1997); Natural Resources Defense Council, Inc. v. Texaco Rfg. and Mktg., Inc., 2 F. 3d 493, 503­504 (CA3 1993); Atlantic States Legal Foundation, Inc. v. Pan American Tanning Corp., 993 F. 2d 1017, 1020­1021 (CA2 1993); Atlantic States Legal Foundation, Inc. v. Tyson Foods, Inc., 897 F. 2d 1128, 1135­1136 (CA11 1990). II A The Constitution's case-or-controversy limitation on Cite as: 528 U. S. ____ (2000) 9 Opinion of the Court federal judicial authority, Art. III, §2, underpins both our standing and our mootness jurisprudence, but the two inquiries differ in respects critical to the proper resolution of this case, so we address them separately. Because the Court of Appeals was persuaded that the case had become moot and so held, it simply assumed without deciding that FOE had initial standing. See Arizonans for Official English v. Arizona, 520 U. S. 43, 66­67 (1997) (court may assume without deciding that standing exists in order to analyze mootness). But because we hold that the Court of Appeals erred in declaring the case moot, we have an obligation to assure ourselves that FOE had Article III standing at the outset of the litigation. We therefore address the question of standing before turning to moot- ness. In Lujan v. Defenders of Wildlife, 504 U. S. 555, 560­561 (1992), we held that, to satisfy Article III's standing re- quirements, a plaintiff must show (1) it has suffered an "injury in fact" that is (a) concrete and particularized and (b) actual or imminent, not conjectural or hypothetical; (2) the injury is fairly traceable to the challenged action of the defendant; and (3) it is likely, as opposed to merely speculative, that the injury will be redressed by a favor- able decision. An association has standing to bring suit on behalf of its members when its members would otherwise have standing to sue in their own right, the interests at stake are germane to the organization's purpose, and neither the claim asserted nor the relief requested re- quires the participation of individual members in the lawsuit. Hunt v. Washington State Apple Advertising Comm'n, 432 U. S. 333, 343 (1977). Laidlaw contends first that FOE lacked standing from the outset even to seek injunctive relief, because the plain- tiff organizations failed to show that any of their members had sustained or faced the threat of any "injury in fact" from Laidlaw's activities. In support of this contention 10 FRIENDS OF EARTH, INC. v. LAIDLAW ENVI- RONMENTAL SERVICES (TOC), INC. Opinion of the Court Laidlaw points to the District Court's finding, made in the course of setting the penalty amount, that there had been "no demonstrated proof of harm to the environment" from Laidlaw's mercury discharge violations. 956 F. Supp., at 602; see also ibid. ("[T]he NPDES permit violations at issue in this citizen suit did not result in any health risk or environmental harm."). The relevant showing for purposes of Article III stand- ing, however, is not injury to the environment but injury to the plaintiff. To insist upon the former rather than the latter as part of the standing inquiry (as the dissent in essence does, post, at 2­3) is to raise the standing hurdle higher than the necessary showing for success on the merits in an action alleging noncompliance with an NPDES permit. Focusing properly on injury to the plain- tiff, the District Court found that FOE had demonstrated sufficient injury to establish standing. App. in No. 97­ 1246 (CA4), pp. 207­208 (Tr. of Hearing 39­40 (June 30, 1993)). For example, FOE member Kenneth Lee Curtis averred in affidavits that he lived a half-mile from Laid- law's facility; that he occasionally drove over the North Tyger River, and that it looked and smelled polluted; and that he would like to fish, camp, swim, and picnic in and near the river between 3 and 15 miles downstream from the facility, as he did when he was a teenager, but would not do so because he was concerned that the water was polluted by Laidlaw's discharges. Record, Doc. No. 71 (Exhs. 41, 42). Curtis reaffirmed these statements in extensive deposition testimony. For example, he testified that he would like to fish in the river at a specific spot he used as a boy, but that he would not do so now because of his concerns about Laidlaw's discharges. Ibid. (Exh. 43, at 52­53; Exh. 44, at 33). Other members presented evidence to similar effect. CLEAN member Angela Patterson attested that she lived two miles from the facility; that before Laidlaw operated Cite as: 528 U. S. ____ (2000) 11 Opinion of the Court the facility, she picnicked, walked, birdwatched, and waded in and along the North Tyger River because of the natural beauty of the area; that she no longer engaged in these activities in or near the river because she was con- cerned about harmful effects from discharged pollutants; and that she and her husband would like to purchase a home near the river but did not intend to do so, in part because of Laidlaw's discharges. Record, Doc. No. 21 (Exh. 10). CLEAN member Judy Pruitt averred that she lived one-quarter mile from Laidlaw's facility and would like to fish, hike, and picnic along the North Tyger River, but has refrained from those activities because of the discharges. Ibid. (Exh. 7). FOE member Linda Moore attested that she lived 20 miles from Roebuck, and would use the North Tyger River south of Roebuck and the land surrounding it for recreational purposes were she not concerned that the water contained harmful pollutants. Record, Doc. No. 71 (Exhs. 45, 46). In her deposition, Moore testified at length that she would hike, picnic, camp, swim, boat, and drive near or in the river were it not for her concerns about illegal discharges. Ibid. (Exh. 48, at 29, 36­37, 62­63, 72). CLEAN member Gail Lee attested that her home, which is near Laidlaw's facility, had a lower value than similar homes located further from the facility, and that she be- lieved the pollutant discharges accounted for some of the discrepancy. Record, Doc. No. 21 (Exh. 9). Sierra Club member Norman Sharp averred that he had canoed ap- proximately 40 miles downstream of the Laidlaw facility and would like to canoe in the North Tyger River closer to Laidlaw's discharge point, but did not do so because he was concerned that the water contained harmful pollut- ants. Ibid. (Exh. 8). These sworn statements, as the District Court deter- mined, adequately documented injury in fact. We have held that environmental plaintiffs adequately allege injury in fact when they aver that they use the affected area and 12 FRIENDS OF EARTH, INC. v. LAIDLAW ENVI- RONMENTAL SERVICES (TOC), INC. Opinion of the Court are persons "for whom the aesthetic and recreational values of the area will be lessened" by the challenged activity. Sierra Club v. Morton, 405 U. S. 727, 735 (1972). See also Defenders of Wildlife, 504 U. S., at 562­563 ("Of course, the desire to use or observe an animal species, even for purely esthetic purposes, is undeniably a cogniza- ble interest for purposes of standing."). Our decision in Lujan v. National Wildlife Federation, 497 U. S. 871 (1990), is not to the contrary. In that case an environmental organization assailed the Bureau of Land Management's "land withdrawal review program," a program covering millions of acres, alleging that the pro- gram illegally opened up public lands to mining activities. The defendants moved for summary judgment, challeng- ing the plaintiff organization's standing to initiate the action under the Administrative Procedure Act, 5 U. S. C. §702. We held that the plaintiff could not survive the summary judgment motion merely by offering "averments which state only that one of [the organization's] members uses unspecified portions of an immense tract of territory, on some portions of which mining activity has occurred or probably will occur by virtue of the governmental action." 497 U. S., at 889. In contrast, the affidavits and testimony presented by FOE in this case assert that Laidlaw's discharges, and the affiant members' reasonable concerns about the effects of those discharges, directly affected those affiants' recrea- tional, aesthetic, and economic interests. These submis- sions present dispositively more than the mere "general averments" and "conclusory allegations" found inadequate in National Wildlife Federation. Id., at 888. Nor can the affiants' conditional statements- that they would use the nearby North Tyger River for recreation if Laidlaw were not discharging pollutants into it- be equated with the speculative " `some day' intentions" to visit endangered species halfway around the world that we held insufficient Cite as: 528 U. S. ____ (2000) 13 Opinion of the Court to show injury in fact in Defenders of Wildlife. 504 U. S., at 564. Los Angeles v. Lyons, 461 U. S. 95 (1983), relied on by the dissent, post, at 3, does not weigh against standing in this case. In Lyons, we held that a plaintiff lacked standing to seek an injunction against the enforcement of a police chokehold policy because he could not credibly allege that he faced a realistic threat from the policy. 461 U. S., at 107, n. 7. In the footnote from Lyons cited by the dissent, we noted that "[t]he reasonableness of Lyons' fear is de- pendent upon the likelihood of a recurrence of the allegedly unlawful conduct," and that his "subjective apprehensions" that such a recurrence would even take place were not enough to support standing. Id., at 108, n. 8. Here, in contrast, it is undisputed that Laidlaw's unlawful con- duct- discharging pollutants in excess of permit limits- was occurring at the time the complaint was filed. Under Lyons, then, the only "subjective" issue here is "[t]he rea- sonableness of [the] fear" that led the affiants to respond to that concededly ongoing conduct by refraining from use of the North Tyger River and surrounding areas. Unlike the dissent, post, at 3, we see nothing "improbable" about the proposition that a company's continuous and pervasive illegal discharges of pollutants into a river would cause nearby residents to curtail their recreational use of that waterway and would subject them to other economic and aesthetic harms. The proposition is entirely reasonable, the District Court found it was true in this case, and that is enough for injury in fact. Laidlaw argues next that even if FOE had standing to seek injunctive relief, it lacked standing to seek civil pen- alties. Here the asserted defect is not injury but redress- ability. Civil penalties offer no redress to private plain- tiffs, Laidlaw argues, because they are paid to the government, and therefore a citizen plaintiff can never have standing to seek them. 14 FRIENDS OF EARTH, INC. v. LAIDLAW ENVI- RONMENTAL SERVICES (TOC), INC. Opinion of the Court Laidlaw is right to insist that a plaintiff must demon- strate standing separately for each form of relief sought. See, e.g., Lyons, 461 U. S., at 109 (notwithstanding the fact that plaintiff had standing to pursue damages, he lacked standing to pursue injunctive relief); see also Lewis v. Casey, 518 U. S. 343, 358, n. 6 (1996) ("[S]tanding is not dispensed in gross."). But it is wrong to maintain that citizen plaintiffs facing ongoing violations never have standing to seek civil penalties. We have recognized on numerous occasions that "all civil penalties have some deterrent effect." Hudson v. United States, 522 U. S. 93, 102 (1997); see also, e.g., De- partment of Revenue of Mont. v. Kurth Ranch, 511 U. S. 767, 778 (1994). More specifically, Congress has found that civil penalties in Clean Water Act cases do more than promote immediate compliance by limiting the defendant's economic incentive to delay its attainment of permit lim- its; they also deter future violations. This congressional determination warrants judicial attention and respect. "The legislative history of the Act reveals that Congress wanted the district court to consider the need for retribu- tion and deterrence, in addition to restitution, when it imposed civil penalties. . . . [The district court may] seek to deter future violations by basing the penalty on its eco- nomic impact." Tull v. United States, 481 U. S. 412, 422­ 423 (1987). It can scarcely be doubted that, for a plaintiff who is injured or faces the threat of future injury due to illegal conduct ongoing at the time of suit, a sanction that effec- tively abates that conduct and prevents its recurrence provides a form of redress. Civil penalties can fit that description. To the extent that they encourage defendants to discontinue current violations and deter them from committing future ones, they afford redress to citizen plaintiffs who are injured or threatened with injury as a consequence of ongoing unlawful conduct. Cite as: 528 U. S. ____ (2000) 15 Opinion of the Court The dissent argues that it is the availability rather than the imposition of civil penalties that deters any particular polluter from continuing to pollute. Post, at 11­12. This argument misses the mark in two ways. First, it overlooks the interdependence of the availability and the imposition; a threat has no deterrent value unless it is credible that it will be carried out. Second, it is reasonable for Congress to conclude that an actual award of civil penalties does in fact bring with it a significant quantum of deterrence over and above what is achieved by the mere prospect of such penalties. A would-be polluter may or may not be dis- suaded by the existence of a remedy on the books, but a defendant once hit in its pocketbook will surely think twice before polluting again.2 We recognize that there may be a point at which the deterrent effect of a claim for civil penalties becomes so insubstantial or so remote that it cannot support citizen standing. The fact that this vanishing point is not easy to ascertain does not detract from the deterrent power of such penalties in the ordinary case. Justice Frankfurter's observations for the Court, made in a different context nearly 60 years ago, hold true here as well: "How to effectuate policy- the adaptation of means to legitimately sought ends- is one of the most intrac- table of legislative problems. Whether proscribed - - - - - - 2 The dissent suggests that there was little deterrent work for civil penalties to do in this case because the lawsuit brought against Laid- law by DHEC had already pushed the level of deterrence to "near the top of the graph." Post, at 11. This suggestion ignores the District Court's specific finding that the penalty agreed to by Laidlaw and DHEC was far too low to remove Laidlaw's economic benefit from noncompliance, and thus was inadequate to deter future violations. 890 F. Supp. 470, 491­494, 497­498 (SC 1995). And it begins to look especially farfetched when one recalls that Laidlaw itself prompted the DHEC lawsuit, paid the filing fee, and drafted the complaint. See supra, at 5, 6, n. 1. 16 FRIENDS OF EARTH, INC. v. LAIDLAW ENVI- RONMENTAL SERVICES (TOC), INC. Opinion of the Court conduct is to be deterred by qui tam action or triple damages or injunction, or by criminal prosecution, or merely by defense to actions in contract, or by some, or all, of these remedies in combination, is a matter within the legislature's range of choice. Judgment on the deterrent effect of the various weapons in the ar- mory of the law can lay little claim to scientific basis." Tigner v. Texas, 310 U. S. 141, 148 (1940).3 In this case we need not explore the outer limits of the principle that civil penalties provide sufficient deterrence to support redressability. Here, the civil penalties sought by FOE carried with them a deterrent effect that made it likely, as opposed to merely speculative, that the penalties would redress FOE's injuries by abating current viol