Clean Water Act Section 311: Oil Discharge and the Sheen Rule

Under Section 311 of the Clean Water Act, discharging oil into U.S. waters in a quantity that produces a visible sheen is illegal, and the sheen rule at 40 CFR 110.3 is what turns “visible film” into the legal trigger for immediate federal reporting. If oil from your vessel or facility reaches the water and you can see a rainbow film on the surface, sludge on the shoreline, or discoloration, the person in charge must immediately call the National Response Center at 1-800-424-8802.¹ Failing to make that call is a separate federal crime carrying up to five years in prison, and the discharge itself can draw civil fines exceeding $59,000 per day plus per-barrel penalties.²

The Sheen Rule: When a Discharge Becomes “Harmful”

40 CFR 110.3 defines a “harmful quantity” of oil three ways. A discharge is harmful if it violates applicable water quality standards, causes a visible film, sheen, or discoloration on the water’s surface or shoreline, or deposits sludge or emulsion beneath the surface or along the shore.³

The visible-sheen criterion is what most enforcement runs on, and it is deliberately unforgiving. There is no minimum gallon threshold. It takes remarkably little oil to produce that iridescent film. If any observer on scene can see one, the discharge is legally harmful and the clock on your reporting duty has started. No lab test, no volume calculation, no argument about whether the spill was “big enough.”

The water quality standards path exists for cases where oil concentration exceeds limits set under state or federal programs, but it requires testing and is used less often. For practical purposes, assume the sheen test governs.

What Counts as Oil

The statutory definition is broad. It covers crude oil, refined fuel, sludge, oil refuse, and oil mixed with non-dredged waste.² Cooking oil, hydraulic fluid, and lubricating grease all qualify. If a substance can produce a sheen on water, regulators will treat it as oil. The definition is written this way so no operator can escape liability by claiming their product falls outside a narrow category.

Which Waters Are Covered

The prohibition reaches discharges into navigable waters, onto adjoining shorelines, and into the waters of the contiguous zone (up to 24 nautical miles from the baseline of the territorial sea). Federal removal authority extends further still, out to the 200-nautical-mile exclusive economic zone and to any discharge that may affect natural resources under U.S. management.²

What counts as “navigable waters” has shifted with regulatory changes to the definition of “waters of the United States.” As of 2026, two regimes are operating in different states while a proposed nationwide rule remains pending.⁴ The safe operating assumption is straightforward: if a discharge from your site could reasonably reach any surface water or adjoining shoreline, assume federal jurisdiction applies. Betting that a specific ditch or seasonal stream falls outside “waters of the United States” is a bet that federal enforcers may not honor.

How to Report to the National Response Center

The person in charge of the vessel or facility must notify the federal government immediately upon learning of a discharge.² “Immediately” is literal. There is no 24-hour window and no end-of-shift grace period. Delay is a separate violation.

The National Response Center is staffed around the clock by the U.S. Coast Guard. Call 1-800-424-8802.¹ Before dialing, pull together whatever you can of the following:

Location of the discharge, by coordinates or clear description
Type of oil or substance released
Best estimate of quantity, even if rough
Source of the release (leaking pipe, tank overflow, hull breach)
Name and contact for the responsible party
When the discharge was discovered and, if known, when it started

The specialist will assign a report number. Keep it. That number tracks every subsequent federal response action, enforcement letter, and legal document tied to the incident. The NRC then relays the report to federal on-scene coordinators (usually the Coast Guard for coastal spills, EPA for inland ones), who assess whether a federal response is needed.

One protection worth knowing: the notification you provide cannot be used against you personally in a criminal prosecution, except for perjury or false statements.² This applies to natural persons, not corporate entities. The math is simple: reporting immediately shields you from a criminal case built on the report, while not reporting exposes you to prison time.

Calling the NRC does not satisfy state reporting rules. Many states have their own timelines. Underground storage tank operators, for example, must separately report petroleum releases that cause a sheen on nearby surface water to their state or local implementing agency, typically within 24 hours.⁵

Civil Penalties for the Discharge Itself

Section 311 civil penalties come as either administrative fines imposed by EPA or the Coast Guard, or judicial fines pursued in federal court. The current figures reflect inflation adjustments effective since January 2025.

Administrative Penalties

Class I penalties allow up to $23,647 per violation, with a total cap of $59,114 for the whole proceeding. Class II penalties allow up to $23,647 per day of ongoing violation, with a total cap of $295,564.⁶ Class I proceedings are informal and quicker. Class II involves a formal hearing on the record, with more procedural protections and a higher potential total.

Judicial Penalties

Federal court penalties reach $59,114 per day of violation or $2,364 per barrel of oil discharged.⁶ For a multi-day release of any real volume, the arithmetic compounds fast.

Gross negligence or willful misconduct triggers a much harsher tier: a statutory minimum of $236,451, with per-barrel penalties up to $7,093.⁶ The floor means even a single barrel released through gross negligence costs at least a quarter-million dollars in civil penalties alone, before any cleanup bill. Enforcers weigh the violator’s history, the severity of environmental harm, and how cooperative the party was during response when setting the final number.

Criminal Penalties for Not Reporting

Criminal prosecution under Section 311 targets one specific failure: silence. A person in charge who does not immediately notify the federal government of a discharge faces fines under Title 18 and up to five years in prison, or both.² “Person in charge” in practice means the facility manager, plant operator, or vessel captain on duty.

Federal prosecutors treat concealment far more seriously than the spill. A company that spills and reports faces civil penalties and cleanup costs. A company that spills and hides it faces all of that plus criminal charges against the individuals who chose not to call.

Cleanup Costs and When Liability Limits Disappear

Fines are only part of the exposure. The responsible party is also liable for the actual costs of cleaning up the discharge. Section 311 and the Oil Pollution Act of 1990 work together here, with OPA setting liability caps that vary by vessel or facility type. For onshore facilities, the cap is approximately $725.7 million.⁷

Those limits vanish entirely when the responsible party acted with gross negligence or willful misconduct, violated a federal safety or operating regulation, or failed to report. Refusing to cooperate with response officials or ignoring a cleanup order also eliminates the cap. Once liability is unlimited, the responsible party pays every dollar of removal costs and damages, without ceiling.

The Narrow Defenses

Section 311 provides four defenses to removal cost liability. To succeed, you must prove the discharge was caused solely by:

An act of God, meaning an unforeseeable natural event
An act of war
Negligence of the United States government
An act or omission of a third party who has no contractual relationship with you

The word “solely” does the work.² A hurricane that damages a tank you failed to maintain properly is not the sole cause. A contractor’s negligence at your site is not a third-party act because you had a contract with the contractor. These defenses succeed rarely.

Prevention Plans You May Already Need

Reporting and cleanup rules kick in after a spill. Prevention plans exist to keep the spill from happening. Under 40 CFR Part 112, any non-transportation onshore facility that could reasonably discharge oil to navigable waters or adjoining shorelines needs a Spill Prevention, Control, and Countermeasure (SPCC) plan if it stores more than 1,320 gallons of oil aboveground (counting only containers of 55 gallons or larger) or more than 42,000 gallons underground.⁸

The plan must address secondary containment for bulk storage. Containment structures need to hold the full capacity of the largest single tank plus enough extra volume to account for rainfall.⁹ Most facilities must have their SPCC plan certified by a licensed Professional Engineer.¹⁰ Smaller sites may self-certify if they store no more than 10,000 gallons aboveground and have had no reportable discharges in the previous three years.¹¹

Higher-risk facilities need more. A Facility Response Plan (FRP) is required if a facility transfers oil over water and stores at least 42,000 gallons, or stores 1 million gallons or more and meets one of several risk factors (inadequate secondary containment, proximity to fish and wildlife or sensitive environments, proximity to a public drinking water intake, or a reportable discharge of 10,000 gallons or more in the past five years).¹² EPA’s Regional Administrator can also require an FRP after a site-specific review, even without an automatic trigger. The plan must lay out response procedures, identify equipment and personnel, and show capacity to handle a worst-case discharge.

1
U.S. Environmental Protection Agency. National Response Center
2
Office of the Law Revision Counsel. 33 USC 1321 – Oil and Hazardous Substance Liability
3
eCFR. 40 CFR 110.3 – Discharge of Oil in Such Quantities as May Be Harmful
4
Federal Register. Updated Definition of Waters of the United States
5
eCFR. 40 CFR 280.53 – Reporting and Cleanup of Spills and Overfills
6
eCFR. 40 CFR Part 19 – Adjustment of Civil Monetary Penalties for Inflation
7
eCFR. 33 CFR Part 138 Subpart B – OPA 90 Limits of Liability
8
eCFR. 40 CFR Part 112 – Oil Pollution Prevention
9
U.S. Environmental Protection Agency. Secondary Containment for Each Container Under SPCC
10
U.S. Environmental Protection Agency. PE Certification and Applying PEs Seal
11
U.S. Environmental Protection Agency. Is My Facility a Qualified Facility Under the SPCC Rule
12
eCFR. 40 CFR 112.20 – Facility Response Plans