USCG: Ballast Water Management

Ballast water discharged from ships is one of the pathways for the introduction and spread of aquatic nuisance species (ANS). In response to national concerns, the National Invasive Species Act of 1996 (NISA) amended the Nonindigenous Aquatic Nuisance Prevention and Control Act of 1990 (NANPCA).  The Coast Guard has established both regulations and guidelines to prevent the introduction and spread of ANS.
The Coast Guard's final rule on Ballast Water Management was published on March 23, 2012 in the Federal Register, and became effective 90 days after publication, on June 21, 2012.
The Coast Guard amended its regulations on ballast water management by establishing a standard for the allowable concentration of living organisms in ballast water discharged from ships in waters of the United States.  The Coast Guard also amended its regulations for engineering equipment by establishing an approval process for ballast water management systems.
The numerical limits set by the discharge standard in this Final Rule were supported by reports from the National Academy of Science and the U.S. Environmental Protection Agency Science Advisory Board in 2011 as the most stringent that vessels can practicably implement and that the Coast Guard can enforce at this time.
The U.S. Coast Guard has updated its Ballast Water Management FAQ, Volume I.
Source: United States Coast Guard