46 CFR 4.03-65: -65 Significant harm to the environment.

Significant harm to the environment means—

(a) In the navigable waters of the United States, a discharge of oil as set forth in 40 CFR 110.3 or a discharge of hazardous substances in quantities equal to or exceeding, in any 24-hour period, the reportable quantity determined in 40 CFR part 117;

(b) In other waters subject to the jurisdiction of the United States, including the EEZ—

(1) A discharge of oil in excess of the quantities or instantaneous rate permitted in 33 CFR 151.10 or 151.13 during operation of the ship; or

(2) A discharge of noxious liquid substances in bulk in violation of §§ 153.1126 or 153.1128 of this chapter during the operation of the ship; and

(c) In waters subject to the jurisdiction of the United States, including the EEZ, a probable discharge of oil, hazardous substances, marine pollutants, or noxious liquid substances. The factors you must consider to determine whether a discharge is probable include, but are not limited to—

(1) Vessel, floating OCS facility, or MODU location and proximity to land or other navigational hazards;

(2) Weather;

(3) Tide current;

(4) Sea state;

(5) Traffic density;

(6) The nature of damage to the vessel, floating OCS facility, or MODU; and

(7) Failure or breakdown aboard the vessel, floating OCS facility, or MODU, its machinery, or equipment.