Ballast Water Management are methods utilized in order to prevent the transfer and spread of aquatic species in ballast tanks of ships. These methods include the following:
- Mid Ocean BW Exchange: Ballast water that is exchanged 200 nautical miles outside of land masses.
- Empty Refill (ER): In empty/refill exchange, the ballasted tank is emptied by pumps until the pumps lose suction, and then refilled via gravitation and pumping of ocean water. 100% of the ballast water must be emptied from the tank before refilling to complete an empty/refill exchange.
- Flow Through (FT): In the flow-through method of exchange, mid-ocean water is pumped into a full tank or hold from below while the existing coastal water is forced out an opening at the top. A volume of water three times the ballast tank capacity (300%) must be pumped out to complete a flow-through exchange, as mandated by the US Coast Guard.
- Ballast Water Treatment (BW Treatment): treatment of ballast water under the USCG STEP Program, an accepted Alternative Management System (AMS), or a USCG Type Approved Ballast Water Management System.
- Discharge to an onshore treatment facility, or another vessel, for the purposes of treatment pursuant to 33 CFR 151.2025(a)(5).
- US Public Water System source: use only water from a US Public Water System pursuant to 33 CFR 151.2025(a)(2).
- Retain Ballast Water: vessels that have ballast water on board but do not discharge any ballast water within the waters of the United States.