San Francisco BayKeeper (BayKeeper) filed a citizen suit against Tosco Corporation and Diablo Services Corporation (collectively Tosco) claiming that Tosco violated the Clean Water Act (CWA) by illegally discharging petroleum coke into New York Slough, which flows into the San Francisco Bay. BayKeeper claimed that Tosco spilled coke during ship-loading and stored coke on its premises in such a manner as to allow it to be carried into New York Slough by wind and rain. The district court first limited the suit to violations about which BayKeeper had given Tosco specific notice, including the date of violations. The court then granted summary judgment in favor of Tosco, ruling that BayKeeper's claim against Tosco was moot because Tosco sold the facility to another corporation. The Ninth Circuit reversed, ruling that 1) BayKeeper provided sufficient information to Tosco in a notice letter to allow Tosco to determine the dates of violations, and 2) BayKeeper's claim was not moot because civil penalties would serve to deter future violations at the facility.
The CWA authorizes citizens to seek injunctive relief, civil penalties, and attorney fees against individuals found to be in violation of the statute's requirements.  To bring a citizen suit, a claimant must provide the alleged violator sixty-days notice of the intent to sue. Environmental Protection Agency (EPA) regulations require that citizens provide "sufficient information" to allow the recipient to identify the activity and standard violated, the responsible individuals, the location and date of the violation, and the identity of the person giving notice. Failure to provide sufficient notice to the alleged violator warrants dismissal of the suit for lack of subject matter jurisdiction. The Ninth Circuit noted that while failure to provide the identity and contact information of the plaintiffs may be fatal, EPA regulations only require that plaintiffs provide "sufficient information" to allow the defendant to identify the violations and to comply with the law, requiring at most "reasonable specificity."
At issue in the case was whether BayKeeper provided "sufficient information" to allow Tosco to determine the dates of the alleged violations. BayKeeper made two separate claims against Tosco. First, it argued the corporation spilled coke during ship loading. Second, it argued that the corporation allowed coke in uncovered piles to be deposited into the slough by wind and rain. Because BayKeeper listed fourteen dates between 1998 and 1999 when ships had been docked at a Tosco facility, the Ninth Circuit ruled that BayKeeper provided sufficient information for Tosco to determine the dates that coke spilled during ship loading. The court reasoned that Tosco was in a better position than BayKeeper to determine when its own ship loading actually occurred. Further, the court ruled that in addition to alleged violations on the dates listed in the notice letter, BayKeeper could pursue claims for violations on other dates in the same period, in reliance on the court's decision in Community Association for Restoration of the Environment v. Henry Bosma Dairy. In Henry Bosma Dairy, the court ruled that a plaintiff could add additional dates of violations in a complaint if they were "from the same source, were of the same nature, and were easily identifiable" as the violations listed in the notice letter.
The Ninth Circuit ruled that BayKeeper provided sufficient information in its notice letter concerning discharges as a result of improperly covered piles of coke even though BayKeeper only provided a general range of dates of violations. The court reasoned that by identifying the dates as the time when coke piles remained uncovered, BayKeeper provided sufficient information for Tosco to determine when the violations actually took place. The court noted that BayKeeper's notice was sufficient to allow Tosco to correct the problem and to inform Tosco about "what it [was] doing wrong." Finally, the court held that BayKeeper was not obligated to identify specific dates for alleged ongoing violations, thereby eliminating the date requirement for BayKeeper's claim that Tosco did not implement the best available technology to prevent stormwater pollution.
The Ninth Circuit then reached Tosco's argument that BayKeeper's claim was moot because Tosco sold the facility to Ultramar Corporation. To establish mootness, the Ninth Circuit noted that the defendant bears a "heavy burden of persuasion" to show that the court can no longer provide relief to the plaintiff. The court relied on Supreme Court guidance in Friends of the Earth, Inc. v. Laidlaw, in which the court ruled that in CWA cases, civil penalties serve to "deter future violations and thereby redress the injuries that prompted a citizen suitor." According to the Supreme Court, only when it is "absolutely clear that the allegedly wrongful behavior could not reasonably be expected to recur" will a claim for civil penalties be mooted. The Ninth Circuit pointed out that even in Laidlaw, where the facility at issue was permanently closed and dismantled, the Supreme Court remanded the case for further factual findings to determine whether it was "absolutely clear" that violations would not recur. Based on the decision in Laidlaw, the Ninth Circuit reasoned that because the Tosco facilities were still in operation, civil penalties against Tosco would deter potential future violations by the new owner and operator. The court opined that it would "undermine the enforcement mechanisms established by the Clean Water Act" to allow potential violators to avoid liability by selling the facility to a new corporation. The court rejected Tosco's contention that because Ultramar already settled with BayKeeper for its own violations at the facility, deterrence of the new owner was irrelevant.
 Hallstrom v. Tillamook County, 493 U.S. 20 (1989) (refusing to create an exception to notice requirements because notice allows the government agency the opportunity to enforce and allows the potential violator to comply with the law).
 See Wash. Trout v. McCain Foods, Inc., 45 F.3d 1351, 1353 (9th Cir. 1995) (ruling that notice was insufficient because the plaintiffs did not provide the identity of the plaintiffs and therefore the defendants could not contact plaintiffs to negotiate).
 See Cmty. Ass'n for Restoration of the Env't v. Henry Bosma Dairy, 305 F.3d 943, 951 (9th Cir. 2002) (explaining that plaintiffs provided sufficient information of alleged violations in the notice letter even though they included additional violations in their complaint because the additional violations were easily identifiable and from the same source as the violations listed in the notice letter).
 San Francisco BayKeeper, Inc. v. Tosco Corp., 309 F.3d 1153, 1159 (9th Cir. 2002) (quoting United States v. Concentrated Phosphate Exp. Ass'n, 393 U.S. 199, 203 (1968)) (internal quotation marks omitted), cert. dismissed, 123 S. Ct. 2296 (2003).