46 CFR § 167.20-35
Liquid ballast
April 15, 2021
When water ballasting of fuel tanks is necessary, such oily ballast shall not be subsequently discharged overboard within any of the prohibited zones as defined by the Oil Pollution Act, 1961 (33 U.S.C. 1011), except through oily water separators which meet the requirements in 33 CFR 155.330 through 155.380, or directly into sludge barges or shore facilities, or other approved means.
[CGFR 62-17, 27 FR 9046, Sept. 11, 1962, as amended by CGD 95-072, 60 FR 50468, Sept. 29, 1995]