Mr. Justice Brennan
delivered the opinion of the Court.
We review here the reversal by the Court of Appeals for the Third Circuit of respondent's conviction for violation of § 131 of the Rivers and Harbors Act of 1899, [657]*65730 Stat. 1152, 33 U. S. C. § 407. Two questions are presented. The first is whether the Government may prosecute an alleged polluter under § 13 in the absence of the promulgation of a formal regulatory-permit program by the Secretary of the Army.2 The second is whether, if the prosecution is maintainable despite the nonexistence of a formal regulatory-permit program, this respondent was entitled to assert as a defense its alleged reliance on the Army Corps of Engineers’ longstanding administrative construction of § 13 as limited to water deposits that impede or obstruct navigation.
On April 6, 1971, the United States filed a criminal information against the respondent, Pennsylvania In[658]*658dustrial Chemical Corp. (PICCO), alleging that on four separate occasions in August 1970 the corporation had discharged industrial refuse matters3 into the Monongahela River4 in violation of § 13 of the 1899 Act. By its terms, § 13 5 prohibits the discharge or deposit into navigable waters of “any refuse matter of any kind of description whatever other than that flowing from streets and sewers and passing therefrom in a liquid state.” The second proviso to § 13 provides, however, that “the Secretary of the Army . . . may permit the deposit” 6 of refuse matter deemed by the Army Corps of Engineers not to be injurious to navigation, “provided application is made to [the Secretary] prior to depositing such material . ...”7 At trial, it was stipulated that PICCO operated a manufacturing plant on the bank [659]*659of the Monongahela River, that PICCO-owned concrete and iron pipes discharged the refuse matter into the river, and that PICCO had not obtained a permit from the Secretary of the Army prior to the discharges in question. PICCO argued, however, that the discharges did not violate § 13 because (1) the liquid solution flowing from its pipes was “sewage” exempt from the statutory proscription; (2) the discharge did not constitute “refuse matter” within the meaning of § 13 because it was not matter that would “impede navigation”; and (3) the term “refuse” as used in § 13 must be defined in light of the water quality standards established pursuant to the Water Pollution Control Act of 1948 and its amendments.8 In addition, PICCO sought to introduce evidence to show that its failure to obtain a § 13 permit was excusable in this instance because prior to December 19709 the Army Corps of Engineers had not established a formal program for issuing permits under § 13 and, moreover, because the Corps consistently construed § 13 as limited to those deposits that would impede or obstruct navigation, thereby affirmatively misleading PICCO into believing that a § 13 permit was not required as a condition to [660]*660discharges of matter involved in this case. The District Court rejected each of PICCO’s arguments as to the scope and meaning of § 13, disallowed PICCO’s offers of proof on the ground that they were not relevant to the issue of guilt under § 13, and instructed the jury accordingly. PICCO was convicted on all four counts and assessed the maximum fine of $2,500 on each count. 329 F. Supp. 1118 (WD Pa. 1971).
On appeal, the Court of Appeals for the Third Circuit affirmed the District Court’s holdings as to the application of § 13 to the matter discharged by PICCO into the river,10 but rejected the District Court’s conclusion that the § 13 prohibition was operative in the absence of formalized permit procedures. 461 F. 2d 468 (CA3 1972). The Court of Appeals reasoned that this interpretation was tantamount to reading § 13 to be an absolute prohibition against the deposit of any “foreign substance” into the navigable waters of the country and this would have had such a “drastic impact ... on the nation’s economy even in 1899,” id., at 473, that this interpretation could not reasonably be imputed to Congress. Instead, the Court of Appeals concluded that Congress intended to condition enforcement of § 13 on the creation and operation of an administrative permit program. The Court of Appeals stated:
“Congress contemplated a regulatory program pursuant to which persons in PICCO’s position would be able to discharge industrial refuse at the discretion of the Secretary of the Army. It intended criminal penalties for those who failed to comply with this regulatory program. Congress did not, however, intend criminal penalties for people who [661]*661failed to comply with a non-existent regulatory program.” Id., at 475.
The Court of Appeals seems to have found support for this interpretation of § 13 in “Congress’ subsequent enactments in the water quality field.” Id., at 473. The court stated that “[t]here would appear to be something fundamentally inconsistent between the program of developing and enforcing water quality standards under the Water Quality Act and section 407 of the Rivers and Harbors Act [§ 13], if the effect of the latter is to prohibit all discharges of industrial waste into navigable waters.” Ibid. As it viewed the matter, “[w]hat makes the two statutes compatible is the permit program contemplated by Section 13.” Ibid. Accordingly, the Court of Appeals held that it was error for the District Court to have refused PICCO the opportunity to prove the nonexistence of a formal permit program at the time of the alleged offenses.
As an alternative ground for reversal, a majority of the Court of Appeals held that the District Court erred in disallowing PICCO’s offer of proof that it had been affirmatively misled by the Corps of Engineers into believing that it was not necessary to obtain a § 13 permit for the discharge of industrial effluents such as those involved in this case. If such facts were true, the Court of Appeals stated, it would be fundamentally unfair to allow PICCO’s conviction to stand.
Thus, the Court of Appeals set aside PICCO’s conviction and remanded the case to the District Court to give PICCO an opportunity to present the proffered proofs th^t had been disallowed by the District Court.
We granted the Government’s petition for certiorari. 409 U. S. 1074 (1972). We agree with the -Court of Appeals that the District Court’s judgment of conviction must be reversed, but we cannot agree with the Court of Appeals’ interpretation of § 13 as foreclosing [662]*662prosecution in the absence of the existence of a formal regulatory-permit program.
I
Section 13 creates two separate offenses: the discharge or deposit of “any refuse matter” into navigable waters (with the streets-and-sewers exception); and the deposit of “material of any kind” on the bank of any navigable waterway or tributary where it might be washed into the water and thereby impede or obstruct navigation. La Merced, 84 F. 2d 444, 445 (CA9 1936); United States v. Consolidation Coal Co., 354 F. Supp. 173, 175 (ND W. Va. 1973). The second proviso to § 13 authorizes the Secretary of the Army to exempt certain water deposits from the prohibitions of § 13, “provided application is made to him prior to depositing such material.” In exercising that authority, the proviso requires the Secretary to rely on the judgment of the Chief of Engineers that anchorage and navigation will not be injured by such deposits. But, even in a situation where the Chief of Engineers concedes that a certain deposit will not injure anchorage and navigation, the Secretary need not necessarily permit the deposit, for the proviso makes the Secretary's authority discretionary — i. e., it provides that the Secretary “may permit” the deposit. The proviso further requires that permits issued by the Secretary are to prescribe limits and conditions, any violation of which is unlawful. It is crucial to our inquiry, however, that neither the proviso nor any other provision of the statute requires that the Secretary prescribe general regulations or set criteria governing issuance of permits.
Thus, while nothing in § 13 precludes the establishment of a formal regulatory program by the Secretary, it is equally clear that nothing in the section requires the establishment of such a program as a condition to rendering § 13 operative. United States v. Granite State Pack[663]*663ing Co., 470 F. 2d 303, 304 (CA1 1972). In contrast, other provisions of the Rivers and Harbors Act of 1899,11 do include a requirement for regulations. Consequently, we disagree with the Court of Appeals that § 13 itself precludes prosecution for violation of its provisions in the absence of a formal regulatory-permit program.
Similarly, there is nothing in the legislative history of § 13 that supports the conclusion of the Court of Appeals that such a requirement is to be read into the section. Section 13 is one section of a comprehensive law enacted in 1899 to codify pre-existing statutes designed to protect and preserve our Nation’s navigable waterways. United States v. Standard Oil Co., 384 U. S. 224, 226 (1966).
The history of the 1899 Act begins with this Court’s decision in 1888 in Willamette Iron Bridge Co. v. Hatch, 125 U. S. 1. The Court there held that there was no federal common law prohibiting obstructions and nuisances in navigable waters. In response to that decision, Congress passed a series of laws that were later reenacted as the Rivers and Harbors Act of 1899. Section 6 of the first such law, the Rivers and Harbors Act of 1890, provided in part:
“That it shall not be lawful to cast, throw, empty, or unlade, or cause, suffer, or procure to be cast, thrown, emptied, or unladen, either from or out of any ship, vessel, lighter, barge, boat, or other craft, or from the shore, pier, wharf, furnace, manufacturing establishments, or mills of any kind whatever, [664]*664any ballast, stone, slate, gravel, earth, rubbish, wreck, filth, slabs, edgings, sawdust, slag, cinders, ashes, refuse, or other waste of any kind, into any port, road, roadstead, harbor, haven, navigable river, or navigable waters of the United States which shall tend to impede or obstruct navigation, or to deposit or place or cause, suffer, or procure to be deposited or placed, any ballast, stone, slate, gravel, earth, rubbish, wreck, filth, slabs, edgings, sawdust, or other waste in any place or situation on the bank of any navigable waters where the same shall be hable to be washed into such navigable waters, either by ordinary or high tides, or by storms or floods, or otherwise, whereby navigation shall or may be impeded or obstructed: Provided, That nothing herein contained shall extend or be construed to extend . . . to prevent the depositing of any substance above mentioned under a permit from the Secretary of War, which he is hereby authorized to grant, in any place designated by him where navigation will not be obstructed thereby.” 26 Stat. 453.
Four years later, Congress enacted the Rivers and Harbors Act of 1894. Section 6 of that Act provided in part:
“That it shall not be lawful to place, discharge, or deposit, by any process or in any manner, ballast, refuse, dirt, ashes, cinders, mud, sand, dredgings, sludge, acid, or any other matter of any kind other than that flowing from streets, sewers, and passing therefrom in a liquid state, in the waters of any harbor or river of the United States, for the improvement of which money has been appropriated by Congress, elsewhere than within the limits defined and permitted by the Secretary of War; neither shall it be lawful for any person or persons to move, destroy, or injure in any manner whatever any sea [665]*665wall, bulkhead, jetty, dike, levee, wharf, pier, or other work built by the United States, in whole or in part, for the preservation and improvement of any of its navigable waters, or to prevent floods, or as boundary marks, tide gauges, surveying stations, buoys, or other established marks . . . 28 Stat. 363.12
In 1896, Congress commissioned the Secretary of War to compile the various acts protecting navigable waters and “to submit the same to Congress . . . together with such recommendation as to revision, emendation, or enlargement of the said laws as, in his judgment, will be advantageous to the public interest.”13 The Secretary, in turn, delegated the task to the Chief of Engineers, and in February 1897, the Chief of Engineers delivered a draft proposal to the Secretary together with a cover letter that read in part:
“I have the honor to submit herewith (1) a compilation [of the various existing laws protecting navigable waters] and (2) a draft of an act embodying such revision and enlargement of the aforesaid laws as the experience of this office has shown to be advantageous to the public interest.”14
In his compilation, the Chief of Engineers combined the essentials of § 6 of the 1890 Act and of § 6 of the 1894 Act to form the present § 13 of the Rivers and Harbors Act of 1899. Congress enacted the compilation with virtually no debate that contains mention of the intended operative scope of § 13. It seems quite clear, [666]*666however, that § 13 was intended to have no wider or narrower a scope than that of its two predecessor statutes. United States v. Standard Oil Co., 384 U. S., at 227-228. It is true, of course, that the Chief of Engineers was authorized to recommend a “revision” or “enlargement” of the existing laws and that his cover letter accompanying the compilation referred to “a draft of an act embodying such revision and enlargement of the aforesaid laws.” But the revision and enlargement were limited to “the existing law relating to the removal of wrecks,” 15 and even on that subject the changes were minor. Indeed, Senator Frye, the Chairman of the Senate Rivers and Harbors Committee, stated in response to a question whether any great change was made in the existing law by the compilation: “Oh, no. There are not ten words changed in the entire thirteen sections. It is a compilation . . . [with] [v]ery slight changes to remove ambiguities.” 16
Thus, the Court of Appeals’ interpretation of § 13 has no support in the predecessor statutes of § 13. Plainly, neither of the predecessor statutes contemplated that application of their operative provisions would turn on the existence of a formal regulatory program. On the contrary, § 6 of the 1890 Act provided only that its absolute ban on the discharge of enumerated substances could not be construed “to prevent” the Secretary of War from granting, in his discretion, a permit to deposit such material into navigable waters. And § 6 of the 1894 Act contained no direct permit authorization whatsoever.17
[667]*667We turn, then, to the Court of Appeals’ assertion that its conclusion is supported by later congressional enactments in the water quality field. In this regard, the Court of Appeals placed primary reliance18 on the 1965 [668]*668and 1970 amendments to the Water Pollution Control Act of 1948 — the Water Quality Act of 1965, 79 Stat. 903, and the Water Quality Improvement Act of 1970, 84 Stat. 91:19 The Court of Appeals concluded that since the 1965 and 1970 Acts contemplated that discharges must meet minimum water quality standards, as set forth by state agencies, it would be “fundamentally inconsistent” to read § 13 as imposing a ban on all pollutant discharges. 461 F. 2d, at 473. We cannot agree. The Water Quality Acts were a congressional attempt to enlist state and local aid in a concentrated water pollution control and abatement program. The legislative directive of those statutes was that state and local officials, working in cooperation with federal officials, establish minimum water quality standards and create pollution prevention and abatement programs. Nothing in the statutes or their parent statute operated to permit discharges that would otherwise be prohibited by § 13, and in each case Congress specifically provided that the new statutes were not to be construed as “affecting or impairing the provisions of [ § 13 of the Rivers and Harbors Act of 1899].”20
Indeed, the water quality legislation expressly complements the provisions of § 13 of the 1899 Act. Section 13, although authorizing the Secretary of the Army to permit certain water deposits, contains no criteria to be followed by the Secretary in issuing such permits. The water quality legislation, on the other hand, calls for [669]*669the setting of minimum water quality standards, and once such standards are established, federal permit authority, such as that vested in the Secretary of the Army by the second proviso to § 13, is specifically limited to that extent — i. e., a permit could not be granted by the Secretary unless the discharge material met the applicable standards. Water Quality Improvement Act of 1970, § 103, 84 Stat. 107. In essence, therefore, the Water Quality Acts placed a limitation on the Secretary's permit authority without undermining the general prohibitions of § 13. See United States v. Maplewood Poultry Co., 327 F. Supp. 686, 688 (Me. 1971); United States v. United States Steel Corp., 328 F. Supp. 354, 357 (ND Ind. 1970); United States v. Interlake Steel Corp., 297 F. Supp. 912, 916 (ND Ill. 1969).
We, therefore, find nothing fundamentally inconsistent between § 13 and the subsequent federal enactments in the water quality field. Section 13 declares in simple absolutes that have been characterized as “almost an insult to the sophisticated wastes of modern technology” 21 that “[i]t shall not be lawful” to discharge or deposit into navigable waters of the United States “any refuse matter of any kind or description whatever” except as permitted by the Secretary of the Army. In enacting subsequent legislation in the water quality field, Congress took special precautions to preserve the broad prohibitions of § 13 and in no way implied that those prohibitions were operative only under a formal regulatory-permit program. Similarly, nothing in the language or history of § 13 conditions enforcement of its prohibitions on the establishment of a formal regulatory-permit program and, as we have said in the past, “the history of this provision and of related [670]*670legislation dealing with our free-flowing rivers ‘forbids a narrow, cramped reading’ of § 13.” United States v. Standard Oil Co., 384 U. S., at 226; United States v. Republic Steel Corp., 362 U. S. 482, 491 (1960).
II
We turn, therefore, to the Court of Appeals’ alternative ground for reversing PICCO’s conviction, namely, that in light of the longstanding, official administrative construction of § 13 as limited to those water deposits that tend to impede or obstruct navigation, PICCO may have been “affirmatively misled” into believing that its conduct was not criminal.22 We agree with the Court of Appeals that PICCO should have been permitted to present relevant evidence to establish this defense.
At the outset, we observe that the issue here is not whether § 13 in fact applies to water deposits that have no tendency to affect navigation. For, although there was much dispute on this question in the past,23 in [671]*671United States v. Standard Oil Co., supra, we held that “the 'serious injury’ to our watercourses . . sought to be remedied [by the 1899 Act] was caused in part by obstacles that impeded navigation and in part by pollution,” and that the term “refuse” as used in § 13 “includes all foreign substances and pollutants . . . .” 384 U. S., at 228-229, 230.24 See also Illinois v. City of Milwaukee, 406 U. S. 91, 101 (1972). Since then, the lower courts have almost universally agreed, as did the courts below, that § 13 is to be read in accordance with its plain language as imposing a flat ban on the unauthorized deposit of foreign substances into navigable waters, regardless of the effect on navigation. See, e. g., United States v. Granite State Packing Co., 343 F. Supp. 57, aff’d, 470 F. 2d 303 (CA1 1972); United States v. Esso Standard Oil Co. of Puerto Rico, 375 F. 2d 621 (CA3 1967); United States v. Consolidation Coal Co., 354 F. Supp. 173 (ND W. Va. 1973); United States v. Genoa Cooperative Creamery Co., 336 F. Supp. 539 (WD Wis. 1972); United States v. Maplewood Poultry Co., 327 F. Supp. 686 [672]*672(Me. 1971); United States v. United States Steel Corp., 328 F. Supp. 354 (ND Ind. 1970); United States v. Interlake Steel Corp., 297 F. Supp. 912 (ND Ill. 1969) ; contra, Guthrie v. Alabama By-Products Co., 328 F. Supp. 1140 (ND Ala. 1971), aff’d, 456 F. 2d 1294 (CA5 1972).
Nevertheless, it is undisputed that prior to December 1970 the Army Corps of Engineers consistently construed § 13 as limited to water deposits that affected navigation. Thus, at the time of our decision in Standard Oil, the published regulation pertaining to § 13 read as follows:
''§ 209.395. Deposit of refuse. Section 13 of the River and Harbor Act of March 3, 1899 (30 Stat. 1152; 33 U. S. C. 407), prohibits the deposit in navigable waters generally of 'refuse matter of any kind or description whatever other than that flowing from streets and sewers and passing therefrom in a liquid state.’ The jurisdiction of the Department of the Army, derived from the Federal laws enacted for the protection and preservation of the navigable waters of the United States, is limited and directed to such control as may be necessary to protect the public right of navigation. Action under section 13 has therefore been directed by the Department principally against the discharge of those materials that are obstructive or injurious to navigation.” 33 CFR § 209.395 (1967).
In December 1968, the Corps of Engineers published a complete revision of the regulations pertaining to navigable waters. The new regulations pertaining to § § 9 and 10 of the Rivers and Harbors Act of 1899, 33 U. S. C. §§ 401 and 403, dealing with construction and excavation in navigable waters, stated for the first time that the Corps would consider pollution and other conservation and environmental factors in passing on applications [673]*673under those sections for permits to “work in navigable waters.” 33 CFR § 209.120 (d) (1969). But notwithstanding this reference to environmental factors and in spite of our intervening decision in Standard Oil, the new regulation pertaining to § 13 of the 1899 Act continued to construe that provision as limited to water deposits that affected navigation:
“Section 13 of the River and Harbor Act of March 3, 1899 (30 Stat. 1152; 33 U. S. C. 407) authorizes the Secretary of the Army to permit the deposit of refuse matter in navigable waters, whenever in the judgment of the Chief of Engineers anchorage and navigation will not be injured thereby, within limits to be defined and under conditions to be prescribed by him. Although the Department has exercised this authority from time to time, it is considered preferable to act under Section 4 of the River and Harbor Act of March 3, 1905 (33 Stat. 1147; 33 U. S. C. 419). As a means of assisting the Chief of Engineers in determining the effect on anchorage of vessels, the views of the U. S. Coast Guard will be solicited by coordination with the Commander of the local Coast Guard District.” 33 CFR § 209.200 (e) (2) (1969). 25
At trial, PICCO offered to prove that, in reliance on the consistent, longstanding administrative construction of § 13, the deposits in question were made in good-faith belief that they were permissible under law. PICCO [674]*674does not contend, therefore, that it was ignorant of the law or that the statute is impermissibly vague, see Connolly v. General Construction Co., 269 U. S. 385 (1926); Bouie v. City of Columbia, 378 U. S. 347 (1964), but rather that it was affirmatively misled by the responsible administrative agency into believing that the law did not apply in this situation. Cf. Raley v. Ohio, 360 U. S. 423 (1959); Cox v. Louisiana, 379 U. S. 559 (1965).
Of course, there can be no question that PICCO had a right to look to the Corps of Engineers’ regulations for guidance. The Corps is the responsible administrative agency under the 1899 Act, and “the rulings, interpretations and opinions of the [responsible agency] . . . , while not controlling upon the courts by reason of their authority, do constitute a body of experience and informed judgment to which . . . litigants may properly resort for guidance.” Skidmore v. Swift & Co., 323 U. S. 134, 140 (1944); Maritime Board v. Isbrandtsen Co., 356 U. S. 481, 499 (1958). Moreover, although the regulations did not of themselves purport to create or define the statutory offense in question, see United States v. Mersky, 361 U. S. 431 (1960), it is certainly true that their designed purpose was to guide persons as to the meaning and requirements of the statute. Thus, to the extent that the regulations deprived PICCO of fair warning as to what conduct the Government intended to make criminal, we think there can be no doubt that traditional notions of fairness inherent in our system of criminal justice prevent the Government from proceeding with the prosecution. See Newman, Should Official Advice Be Reliable? — Proposals as to Estoppel and Related Doctrines in Administrative Law, 53 Col. L. Rev. 374 (1953); Note, Applying Estoppel Principles in Criminal Cases, 78 Yale L. J. 1046 (1969).
The Government argues, however, that our pronouncement in Standard Oil precludes PICCO from asserting [675]*675reliance on the Corps of Engineers’ regulations and that, in any event, the revised regulation issued in 1968, when considered in light of other pertinent factors,26 was not misleading to persons in PICCO’s position. But we need not respond to the Government’s arguments here, for the substance of those arguments pertains, not to the issue of the availability of reliance as a defense, but rather to the issues whether there was in fact reliance and, if so, whether that reliance was reasonable under the circumstances — issues that must be decided in the first instance by the trial court. At this stage, it is sufficient that we hold that it was error for the District Court to refuse to permit PICCO to present evidence in support of its claim that it had been affirmatively misled into believing that the discharges in question were not a violation of the statute.
Accordingly, the judgment of the Court of Appeals is modified to remand the case to the District Court for further proceedings consistent with this opinion.
It is so ordered.
The Chief Justice, Mr. Justice Stewart, and Mr. Justice Powell