Pursuant to 16 USCS § 4702 (3), [Title 16. Conservation; Chapter 67. Aquatic Nuisance Prevention and Control; General Provisions] the term ballast water means “any water and associated sediments used [..]

Water carried in special (ballast) tanks of ships and used to provide stability needed when carrying less than a full load of cargo and to keep the ship at the proper depth in the water. When the ship is loaded with cargo, the ballast water is released to surrounding waters; when the ship is empty, it takes on more water to keep it upright.

Water, with its suspended matter, taken on board a ship to control trim, list, draught, stability or stresses of the ship

Water taken on board a ship to control trim, list, draught, stability or stresses of a ship. Barrel A unit of volume equal to 42 U.S. gallons or 159 litres at 60 degrees F, often used to measure volum [..]

When not fully loaded, cargo ships must take on water (ballast) to maintain their stability. Once pumped onboard, ballast water is stored in narrow cavities (ballast tanks) built into the hull of a ship.