GEORGE C. PRATT, Circuit Judge:
Defendant Gerónimo Villegas appeals from a judgment entered in the United States District Court for the Eastern District of New York, Edward R. Korman, Judge, convicting him of two counts of knowingly discharging pollutants into the Hudson River in violation of the Clean Water Act (“CWA”). See 33 U.S.C. §§ 1311 and 1319(c)(2). The government cross-appeals, claiming the district court erred in its post-verdict grant of a judgment of acquittal on two counts of violating the knowing-endangerment provisions of the act. See 33 U.S.C. § 1319(c)(3).
FACTS AND BACKGROUND
Villegas was co-owner and vice president of Plaza Health Laboratories, Inc., a blood-testing laboratory in Brooklyn, New York. On at least two occasions between April and [644]*644September 1988, Villegas loaded containers of numerous vials of human blood generated from his business into his personal ear, and drove to his residence at the Admirals Walk Condominium in Edgewater, New Jersey. Once at his condominium complex, Villegas removed the containers from his car and carried them to the edge of the Hudson River. On one occasion he carried two containers of the vials to the bulkhead that separates his condominium complex from the river, and placed them at low tide within a crevice in the bulkhead that was below the high-water line.
On May 26, 1988, a group of eighth graders on a field trip at the Alice Austin House in Staten Island, New York, discovered numerous glass vials containing human blood along the shore. Some of the vials had washed up on the shore; many were still in the water. Some were cracked, although most remained sealed with stoppers in solid-plastic containers or ziplock bags. Fortunately, no one was injured. That afternoon, New York City workers recovered approximately 70 vials from the area.
On September 25, 1988, a maintenance worker employed by the Admirals Walk Condominium discovered a plastic container holding blood vials wedged between rocks in the bulkhead. New Jersey authorities retrieved numerous blood vials from the bulkhead later that day.
Ten of the retrieved vials contained blood infected with the hepatitis-B virus. All of the vials recovered were eventually traced to Plaza Health Laboratories.
Based upon the May 1988 discovery of vials, Plaza Health Laboratories and Villegas were indicted on May 16, 1989, on two counts each of violating §§ 1319(c)(2) and (3) of the Clean Water Act. 33 U.S.C. §§ 1251 et seq. A superseding indictment charged both defendants with two additional CWA counts based upon the vials found in September 1988.
In December of 1990 the district court granted the government’s motion to sever all claims against Plaza Health Laboratories, apparently due to Plaza’s participation in ongoing bankruptcy proceedings. The government then proceeded to trial against Villegas only.
Counts II and IV of the superseding indictment charged Villegas with knowingly discharging pollutants from a “point source” without a permit. See 33 U.S.C. §§ 1311(a), 1319(e)(2). Counts I and III alleged that Villegas had discharged pollutants, knowing that he placed others in “imminent danger of death or serious bodily injury”. See 33 U.S.C. § 1319(c)(3). On January 31, 1991, following a trial before Judge Korman, the jury found Villegas guilty on all four counts.
Renewing a motion made at trial, Villegas moved for a judgment of acquittal on all counts under rule 29 of the Federal Rules of Criminal Procedure. Judge Korman granted the motion on counts I and III, holding that he had incorrectly instructed the jury on the act’s “knowing endangerment” provisions. This ruling is reported at 784 F.Supp. 6, 13-14 (E.D.N.Y.1991). The district judge denied the motion on counts II and IV, rejecting arguments that the act did not envision a human being as a “point source”. 784 F.Supp. at 10-11.
Judge Korman sentenced Villegas on counts II and IV to two concurrent terms of twelve months’ imprisonment, one year of supervised release, and a $100 special assessment. Execution of the sentence was stayed pending this appeal.
Villegas contends that one element of the CWA crime, knowingly discharging pollutants from a “point source”, was not established in his case. He argues that the definition of “point source”, 33 U.S.C. § 1362(14), does not include discharges that result from the individual acts of human beings. Raising primarily questions of legislative intent and statutory construction, Villegas argues that at best, the term “point source” is ambiguous as applied to him, and that the rule of lenity should result in reversal of his convictions. The government has cross-appealed from the district court’s post-verdict order acquitting Villegas on the two knowing-endangerment counts.
DISCUSSION
Because “discharge from a point source” is an essential element of a “knowing” violation [645]*645as well as a “knowing endangerment” violation, see 33 U.S.C. §§ 1319(c)(2) — (3) and discussion infra, we need not address the government’s contentions regarding the CWA’s definition of “imminent danger” if we should conclude that Villegas’s discharges were not “from a point source”. We therefore consider the “point source” issue first.
A. Navigating the Clean Water Act.
The basic prohibition on discharge of pollutants is in 33 U.S.C. § 1311(a), which states:
Except as in compliance with this section and sections 1312, 1316, 1317, 1328, 134-2, and 1344 of this title, the discharge of any pollutant by any person shall be unlawful.
Id. (emphasis added).
The largest exception to this seemingly absolute rule is found in 33 U.S.C. § 1342, which establishes the CWA’s national pollutant discharge elimination system, or NPDES:
(a) Permits for discharge of pollutants (1) Except as provided in sections 1328 [aquaculture] and 1344 of this title [dredge and fill permits], the Administrator may, after opportunity for public hearing, issue a permit for the discharge of any pollutant * * * notwithstanding section 1311(a) of this title, upon condition that such discharge will meet * * * all applicable requirements under sections 1311, 1312, 1316, 1317, 1318, and 1343 of this title * * *
33 U.S.C. § 1342(a) (emphasis added).
Reading § 1311(a), the basic prohibition, and § 1342(a)(1), the permit section, together, we can identify the basic rule, our rhumb line to clean waters, that, absent a permit, “the discharge of any pollutant by any person” is unlawful. 33 U.S.C. § 1311(a).
We must then adjust our rhumb line by reference to two key definitions — “pollutant” and “discharge”. “Pollutant” is defined, in part, as “biological materials * * * discharged into water.” 33 U.S.C. § 1362(6) (emphasis added). “Discharge”, in turn, is “any addition of any pollutant to navigable waters from any point source * * *.” (emphasis added). 33 U.S.C. § 1362(12).
As applied to the facts of this case, then, the defendant “added” a “pollutant” (human blood in glass vials) to “navigable waters” (the Hudson River), and he did so without a permit. The issue, therefore, is whether his conduct constituted a “discharge”, and that in turn depends on whether the addition of the blood to the Hudson River waters was “from any point source”.
For this final course adjustment in' our navigation, we look again to the statute.
(14) The term “point source” means any discernible, confined and discrete conveyance, including but not limited to any pipe, ditch, channel, tunnel', conduit, well, discrete fissure, container, rolling stock, concentrated animal feeding operation, or vessel or other floating craft, from which pollutants are or may be discharged. This term does not include agricultural storm-water discharges and return flows from irrigated agriculture.
33 U.S.C. § 1362(14).
During and after Villegas’s trial, Judge Korman labored over how to define “point source” in this case. At one point he observed that the image of a human being is not “conjured up” by congress’s definition of “point source”. Ultimately, he never defined the “point source” element but he did charge the jury:
Removing pollutants from a container, and a vehicle is a container, parked next to a navigable body of water and physically throwing the pollutant into the water constitutes a discharge from a point source.
In ruling on Villegas’s rule 29 motion, however, Judge Korman held that the element “point source” may reasonably be read
to include any discrete and identifiable conduit — including a human being — designated to collect or discharge pollutants produced in the course of a waste-generating activity, (emphasis added).
As the parties have presented the issue to us in their briefs and at oral argument, the question is “whether a human being can be a point source”. Both sides focus on the district court’s conclusion in its rule 29 memorandum that, among other things, the requi[646]*646site “point source” here could be Villegas himself.
Significantly, the jury was never clearly instructed on this legal theory, and the instruction actually given bordered on an improper removal of the determination of an essential element of the crime from the jury’s consideration. Serious problems might be presented by the government’s attempt to justify Judge Korman’s post-verdict definitional efforts as an alternate theory upon which to uphold Villegas’s convictions. Chiarella v. United States, 445 U.S. 222, 236, 100 S.Ct. 1108, 1118, 63 L.Ed.2d 348 (1980) (court may not affirm criminal conviction on basis of theory not presented to jury).
However, far more fundamental than any error in jury instructions is the problem highlighted by the district court’s analytical struggle to find somewhere in the Villegas transaction a “discernible, confined and discrete conveyance”. Simply put, that problem is that this statute was never designed to address the random, individual polluter like Villegas.
To determine the scope of the CWA’s “point source” definition, we first consider the language and structure of the act itself. If the language is not plain, an excursion into legislative history and context may prove fruitful. Judicial interpretations of the term can be instructive as well, as may be interpretive statements by the agency in charge of implementing the statute. If we conclude after this analysis that the statute is ambiguous as applied to Villegas, then the rule of lenity may apply. Moskal v. United States, 498 U.S. 103, 107, 111 S.Ct. 461, 465, 112 L.Ed.2d 449 (1990); United States v. Concepcion, 983 F.2d 369, 380 (2d Cir.1992).
1. Language and Structure of Act.
Human beings are not among the enumerated items that may be a “point source”. Although by its terms the definition of “point source” is nonexclusive, the words used to define the term and the examples given (“pipe, ditch, channel, tunnel, conduit, well, discrete fissure”, etc.) evoke images of physical structures and instrumental-ities that systematically act as a means of conveying pollutants from an industrial source to navigable waterways.
In addition, if every discharge involving humans were to be considered a “discharge from a point source”, the statute’s lengthy definition of “point source” would have been unnecessary. It is elemental that congress does not add unnecessary words to statutes. Had congress intended to punish any human being who polluted navigational waters, it could readily have said: “any person who places pollutants in navigable waters without a permit is guilty of a crime.”
The Clean Water Act generally targets industrial and municipal sources of pollutants, as is evident from a perusal of its many sections. Consistent with this focus, the term “point source” is used throughout the statute, but invariably in sentences referencing industrial or municipal discharges. See, e.g., 33 U.S.C. § 1311 (referring to “owner or operator” of point source); § 1311(e) (requiring that effluent limitations established under the Act “be applied to all point sources of discharge”); § 1311(g)(2) (allows an “owner or operator of a point source” to apply to EPA for modification of its limitations requirements); § 1342(f) (referring to classes, categories, types, and sizes of point sources); § 1314(b)(4)(B) (denoting “best conventional pollutant control technology measures and practices” applicable to any point source within particular category or class); § 1316 (“any point source * * * which is constructed as to meet all applicable standards of performance”); § 1318(a) (administrator shall require owner or operator of any point source to install, use and maintain monitoring equipment or methods); and § 1318(c) (states may develop procedures for inspection, monitoring, and entry with respect to point sources located in state).
This emphasis was sensible, as “[ijndustrial and municipal point sources were the worst and most obvious offenders of surface water quality. They were also the easiest to address because their loadings emerge from a discrete point such as the end of a pipe.” David Letson, Point/Nonpoint Source Pollution Reduction Trading: An Interpretive Survey, 32 Nat.Resources J. 219, 221 (1992).
[647]*647Finally on this point, we assume that congress did not intend the awkward meaning that would result if we were to read “human being” into the definition of “point source”. Section 1362(12)(A) defines “discharge of a pollutant” as “any addition of any pollutant to navigable waters from any point source”. Enhanced by this definition, § 1311(a) reads in effect “the addition of any pollutant to navigable waters from any point source by any person shall be unlawful” (emphasis added). But were a human being to be included within the definition of “point source”, the prohibition would then read: “the addition of any pollutant to navigable waters from any person by any person shall be unlawful”, and this simply makes no sense. As the statute stands today, the term “point source” is comprehensible only if it is held to the context of industrial and municipal discharges.
2. Legislative History and Context.
The broad remedial purpose of the CWA is to “restore and maintain the chemical, physical, and biological integrity of the Nation’s waters”. 33 U.S.C. § 1251(a). The narrow questions posed by this case, however, may not be resolved merely by simple reference to this admirable goal. See National Wildlife Fed’n v. Gorsuch, 693 F.2d 156, 178 (D.C.Cir.1982) (“it is one thing for Congress to announce a grand goal, and quite another for it to mandate full implementation of that goal”). We agree with the court in National Wildlife Fed’n that “even if we accept the purposes section at face value, it is only suggestive, not dispositive of [the issue before us]. Caution is always advisable in relying on a general declaration of purpose to alter the apparent meaning of a specific provision.” Id.
The legislative history of the CWA, while providing little insight into the meaning of “point source”, confirms the act’s focus on industrial polluters. Congress required NPDES permits of those who discharge from a “point source”. The term “point source”, introduced to the act in 1972, was intended to function as a means of identifying industrial polluters — generally a difficult task because pollutants quickly disperse throughout the subject waters. The senate report for the 1972 amendments explains:
In order to further clarify the scope of the regulatory procedures in the Act the Committee had added a definition of point source to distinguish between control requirements where there are specific confined conveyances, such as pipes, and control requirements which are imposed to control runoff. The control of pollutants from runoff is applied pursuant to section 209 and the authority resides in the State or other local agency.
S.Rep. No. 92-414, reprinted in 1972 U.S.C.C.A.N. 3668, 3744.
Senator Robert Dole added his comments to the committee report:
Most of the problems of agricultural pollution deal with non-point sources. Very simply, a non-point source of pollution is one that does not confine its polluting discharge to one fairly specific outlet, such as a sewer pipe, a drainage ditch or a conduit; thus, a feedlot would be considered to be a non-point source as would pesticides and fertilizers.
Id. at 3760 (supplemental views). See also National Wildlife Fed’n, 693 F.2d at 175 (congress’s focus was on traditional industrial and municipal wastes); E.I. du Pont de Nemours & Co. v. Train, 430 U.S. 112, 118-21, 97 S.Ct. 965, 970-71, 51 L.Ed.2d 204 (1977) (outlines EPA scheme of effluent limitations for subject industrial groups).
We find no suggestion either in the act itself or in the history of its passage that congress intended the CWA to impose criminal liability on an individual for the myriad, random acts of human waste disposal, for example, a passerby who flings a candy wrapper into the Hudson River, or a urinating swimmer. Discussions during the passage of the 1972 amendments indicate that congress had bigger fish to fry.
The 1972 congress modeled the NPDES, its aggressive new permitting program, after the Rivers and Harbors Act of 1899 (“RHA”; known also as the Refuse Act), 33 U.S.C. § 401, et seq. See S.Rep. No. 92-414, reprinted in 1972 U.S.C.C.A.N. 3668, 3672 & 3738. The CWA’s focus on transporting pol[648]*648lutants to navigable waters via the “point source” mechanism represented a departure from the RHA’s more general approach:
It shall not be lawful to throw, discharge, or deposit * * * any refuse matter of any kind or description whatever other than that flowing from streets and sewers and passing therefrom in a liquid state, into any navigable water of the United States
33 U.S.C. § 407.
Unlike §§ 1311 and 1319(c)(2) of the CWA, the RHA’s relevant criminal provision, 33 U.S.C. § 411, has been held to provide for strict liability, and the most severe criminal penalty is a misdemeanor. United States v. White Fuel Corp., 498 F.2d 619, 622 (1st Cir.1974). Accordingly, we view with skepticism the government’s contention that we should broadly construe the greatly magnified penal provisions of the CWA based upon RHA cases that did so in the context of strict-liability and misdemeanor penalties. See, e.g., United States v. Standard Oil Co., 384 U.S. 224, 229-30, 86 S.Ct. 1427, 1429-30, 16 L.Ed.2d 492 (1966) (holding “refuse matter” in § 407 includes commercially valuable gasoline accidentally discharged into navigable river); United States v. American Cyanamid Co., 354 F.Supp. 1202, 1205 (S.D.N.Y.1973) (construing RHA broadly, court held that refuse discharged into tributary satisfied “navigable waters” requirement); see also United States v. Republic Steel Corp., 362 U.S. 482, 489-91, 80 S.Ct. 884, 888-90, 4 L.Ed.2d 903 (1960) (RHA construed broadly in injunction context; RHA “obstruction” included liquid matter discharged from mills which impaired navigation by settling in bottom of channel).
3. Caselaw.
Our search for the meaning of “point source” brings us next to judicial constructions of the term.
The “point source” element was clearly established in the few CWA criminal decisions under § 1319(e) that are reported. See United States v. Boldt, 929 F.2d 35, 37-38 (1st Cir.1991) (discharge of partially untreated industrial wastewater from storage tank directly into municipal sewer); United States v. Frezzo Bros., Inc., 602 F.2d 1123, 1125 (3d Cir.1979) (compost materials discharged from pipe into tributary of creek), cert. denied, 444 U.S. 1074, 100 S.Ct. 1020, 62 L.Ed.2d 756 (1980); United States v. Hamel, 551 F.2d 107, 108 (6th Cir.1977) (gasoline pumped into lake from underground tank); cf. United States v. Oxford Royal Mushroom Products, Inc., 487 F.Supp. 852, 854 (E.D.Pa.1980) (overflow of spray-irrigation system discharging waste water into nearby stream is “point source” discharge).
With the exception of Oxford Royal Mushroom, supra, the cases that have interpreted “point source” have done so in civil-penalty or licensing settings, where greater flexibility of interpretation to further remedial legislative purposes is permitted, and the rule of lenity does not protect a defendant against statutory ambiguities. See, e.g., Avoyelles Sportsmen’s League, Inc. v. Marsh, 715 F.2d 897, 922 (5th Cir.1983) (“point source” includes bulldozing equipment that discharged dredged materials onto wetland).
For example, our circuit recently held in Dague v. City of Burlington, a civil-penalty case, that a discharge of pollutant-laden leachate into a culvert leading to navigable waters was through a “point source”. 935 F.2d 1343, 1354-55 (2d Cir.1991), rev’d in part on other grounds, — U.S. -, 112 S.Ct. 2638, 120 L.Ed.2d 449 (1992). But in Dague, unlike in this case, the city’s discharge involved a culvert, one of the specifically enumerated examples of a “point source” set forth in § 1362(14). Dague, 935 F.2d at 1354. Dague thus presented a classic “point source” discharge.
The government relies on broad dicta in another civil case, United States v. Earth Sciences, Inc., 599 F.2d 368, 373 (10th Cir.1979), in which the court held “[t]he concept of a point source was designed to further this [permit regulatory] scheme by embracing the broadest possible definition of any identifiable conveyance from which pollutants might enter the waters of the United States.” We do not find this Earth Sciences dicta persuasive here, however, because that court found a “point source” in a ditch used in the mining operation — certainly not a far leap when [649]*649“ditch” also is an expressly listed example of a “point source”. We cannot, however, make the further leap of writing “human being” into the statutory language without doing violence to the language and structure of the CWA.
4. Regulatory Structure.
Finally, not even the EPA’s regulations support the government’s broad assertion that a human being may be a “point source”. Cf. National Wildlife Fed’n, 698 F.2d at 166-67 & 173 n. 54 (as EPA has power to define point and nonpoint sources in CWA, courts must give great deference to EPA’s construction of “point source”). The EPA stresses that the discharge be “through pipes, sewers, or other conveyances”:
Discharge of a pollutant means:
(a) Any addition of any “pollutant” or combination of pollutants to “waters of the United States” from any “point source”.
í¡í 5^ $ ijs % íjí
This definition includes additions of. pollutants into waters of the United States from: surface runoff which is collected or channelled by man; discharges through pipes, sewers, or other conveyances owned by a State, municipality, or other person which do not lead to a treatment works; and discharges through pipes, sewers, or other conveyances, leading into privately owned treatment works. This term does not include an addition of pollutants by any “indirect discharger.”
40 C.F.R. § 122.2 (1992) (emphasis supplied).
In sum, although congress had the ability to so provide, § 1362(14) of the CWA does not expressly recognize a human being as a “point source”; nor does the act make structural sense when one incorporates a human being into that definition. The legislative history of the act adds no light to the muddy depths of this issue, and cases urging a broad interpretation of the definition in the civil-penalty context do not persuade us to do so here, where congress has imposed heavy criminal sanctions. Adopting the government’s suggested flexibility for the definition would effectively read the “point source” element of the crime out of the statute, and not even the EPA has extended the term “point source” as far as is urged here.
We accordingly conclude that the term “point source” as applied to a human being is at best ambiguous.
B. Rule of Lenity.
In criminal prosecutions the rule of lenity requires that ambiguities in the statute be resolved in the defendant’s favor. Crandon v. United States, 494 U.S. 152, 168, 110 S.Ct. 997, 1006, 108 L.Ed.2d 132 (1990) (ambiguity in criminal statute resolved in defendant’s favor “unless and until Congress plainly states that we have misconstrued its intent”); Bifulco v. United States, 447 U.S. 381, 387, 100 S.Ct. 2247, 2252, 65 L.Ed.2d 205 (1980) (same); Huddleston v. United States, 415 U.S. 814, 830-31, 94 S.Ct. 1262, 1271-72, 39 L.Ed.2d 782 (1974) (ambiguity concerning ambit of criminal statutes should be resolved in favor of lenity). In other words, we cannot add to the statute what congress did not provide. “[BJefore a man can be punished as a criminal under the Federal law his case must be ‘plainly and unmistakably’ within the provisions of some statute.” United States v. Gradwell, 243 U.S. 476, 485, 37 S.Ct. 407, 411, 61 L.Ed. 857 (1917).
Since the government’s reading of the statute in this case founders on our inability to discern the “obvious intention of the legislature”, Huddleston, 415 U.S. at 831, 94 S.Ct. at 1272, to include a human being as a “point source”, we conclude that the criminal provisions of the CWA did not clearly proscribe Villegas’s conduct and did not accord him fair warning of the sanctions the law placed on that conduct. Under the rule of lenity, therefore, the prosecutions against him must be dismissed.
C. Knowing Endangerment.
As noted above, our ruling on “point source” obviates the need for us to address the government’s cross-appeal that the district court erred in acquitting Villegas of two counts of “knowing endangerment” when it adopted post-trial a different definition of [650]*650“imminent danger” than what it had included in its charge to the jury. We affirm the district court’s acquittal on these two counts on the same ground upon which we reverse the other two counts: defendant’s discharges were not from a “point source” as defined in the act.
CONCLUSION
The Clean Water Act targets industrial and municipal production of pollutants. Its criminal provisions do not reach actions such as those done by Villegas, despite their heinous character. While we might think it desirable to punish such an obviously wrong act, we must nevertheless ensure that we apply the statute as congress wrote it, giving Villegas the benefit of the substantial ambiguity in its meaning. Justice Douglas’s comments, made in reviewing a 1966 prosecution under the Rivers and Harbors Act, are equally appropriate today:
This case comes to us at a time in the Nation’s history when there is greater concern than ever over pollution — one of the main threats to our free-flowing rivers and to our lakes as well. The crisis that we face in this respect would not, of course, warrant us in manufacturing offenses where Congress has not acted nor in stretching statutory language in a criminal field to meet strange conditions.
Standard Oil Co., 384 U.S. at 225, 86 S.Ct. at 1428.
Compelled by the rule of lenity, we reverse Villegas’s judgment of conviction and remand with a direction to dismiss the indictment.
Convictions reversed; cross-appeal affirmed.