40 CFR 110: EPA Discharge of Oil Regulation

Regulatory citation: Clean Water Act Section 311; 40 CFR Part 110, Discharge of Oil

What Is EPA's Discharge of Oil Regulation?

Part 110 defines when a discharge of oil is in a quantity that may be harmful to public health or welfare or the environment under Section 311 of the Clean Water Act. Discharges that meet this definition are prohibited, and the person in charge of the vessel or facility must report them immediately to the National Response Center (NRC).

The rule is often called the sheen rule, because a visible sheen on the water is one of the triggers. It applies to oil of any kind, including petroleum products such as gasoline, diesel and lubricating oil, and non-petroleum oils such as vegetable oils and animal fats. It applies to discharges into or upon navigable waters of the United States and adjoining shorelines, and to certain other waters covered by Section 311.

Why the Sheen Rule Matters

The regulation sets no minimum volume. A few gallons of oil that reach a storm drain and leave a sheen on a creek can trigger the reporting duty. Failing to report a discharge you know about is a separate violation from the discharge itself, so facilities need to recognize reportable spills quickly.

Core Obligations

1. Know What Makes a Discharge Harmful (110.3)

A discharge of oil is in a quantity that may be harmful if it does either of the following: violates applicable water quality standards, or causes a film or sheen upon, or discoloration of, the surface of the water or adjoining shorelines, or causes a sludge or emulsion to be deposited beneath the surface of the water or upon adjoining shorelines. A sheen is defined as an iridescent appearance on the surface of water.

2. Do Not Use Dispersants to Hide a Discharge (110.4)

Adding any chemical or biological agent, or any other substance, to oil to be discharged in a way that would circumvent Part 110 is prohibited. A discharge does not stop being reportable because a soap or dispersant has been applied to break up the sheen.

3. Understand the Limited Exemptions (110.5)

Certain discharges are not considered harmful under this part. They include discharges of oil from a properly functioning vessel engine, including oil accumulated in a vessel's bilges, when discharged in compliance with MARPOL 73/78, Annex I, other discharges permitted under MARPOL Annex I, and discharges the EPA Administrator expressly permits for research, demonstration projects or studies on oil pollution. These exemptions are narrow and generally do not apply to onshore facility spills.

4. Report Immediately to the National Response Center (110.6)

Any person in charge of a vessel or of an onshore or offshore facility must, as soon as they have knowledge of a prohibited discharge, immediately notify the NRC at 800-424-8802. If direct reporting to the NRC is not practicable, reports may be made to the Coast Guard or the EPA predesignated On-Scene Coordinator for the area, who will relay them to the NRC. If none of these can be reached immediately, the nearest Coast Guard unit may be notified, as long as the NRC is notified as soon as possible.

5. Coordinate With Other Reporting Duties

A call to the NRC does not satisfy every reporting obligation. State and local agencies often have their own spill reporting rules and deadlines. Facilities subject to the SPCC rule may also need to send a written report to the EPA Regional Administrator under section 112.4 after certain discharges.

Common Compliance Approaches

Post the NRC Number

Display the NRC number and state spill hotline at fuel transfer areas, tank farms and maintenance shops.

Train for Recognition

Teach staff what a sheen looks like, where drains and ditches lead, and that any sheen on water is a reportable event.

Use a Spill Decision Tree

Give supervisors a simple flowchart: Did oil reach water or a shoreline? Is there a sheen, discoloration or sludge? If yes, call the NRC immediately, then notify state and local agencies.

Document Every Call

Record the date, time, NRC report number, caller and the information given, along with photos of the release.

Example: The Sheen Rule in Practice

A hydraulic hose bursts on a loader at a gravel pit, and about five gallons of hydraulic oil runs into a drainage ditch that flows to a nearby stream. The site supervisor sees a rainbow sheen on the stream within minutes. Although the volume is small, the sheen makes the discharge reportable. The supervisor calls the NRC right away, records the report number, and then calls the state spill line as required by state law. Crews deploy absorbent booms in the ditch, and the company reviews its equipment inspection routine to prevent repeat hose failures.

Related regulations: EPA SPCC plans, EPA facility response plans, EPA release reporting.

Note: This summary reflects federal EPA requirements under the Clean Water Act. States and local agencies often have separate oil spill reporting requirements, sometimes for spills to land as well as water. Always check the current regulation text and your state requirements.

Frequently Asked Questions

Is there a minimum quantity of oil that must be reported?

No. Reportability depends on the effect of the discharge, such as a sheen, discoloration, sludge or emulsion, or a violation of water quality standards, not on the volume released.

Who must make the report?

The person in charge of the vessel or onshore or offshore facility must notify the NRC immediately upon knowledge of the discharge.

Does the rule cover vegetable oil?

Yes. The rule applies to oil of any kind, including non-petroleum oils such as vegetable oils and animal fats.